Lithium-doped lanthanum zirconium oxygen material, method for producing the same, and battery

Abstract

The application relates to the technical field of solid electrolytes, and provides a doped lithium lanthanum zirconium oxide material, a preparation method thereof and a battery. The preparation method comprises the following steps: mixing a lithium source, a lanthanum source, a zirconium source, a doped M source and an organic solvent, and ball milling to obtain a first mixture, wherein the volume average particle size D50 of particles in the first mixture is less than or equal to 500 nm; spray drying the first mixture to obtain a precursor powder; and sintering the precursor powder to prepare the doped lithium lanthanum zirconium oxide material. The application can form a dense and high-purity cubic phase LLZO, and the process has good repeatability and is suitable for large-scale production.

Description

Technical Field

[0001] This application relates to the field of solid electrolyte technology, and in particular to lithium-doped lanthanum zirconium oxide materials, their preparation methods, and batteries. Background Technology

[0002] Lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 LLZO, as one of the most promising solid-state electrolyte materials, exists in two crystal forms: cubic and tetragonal. Cubic LLZO exhibits higher lithium-ion conductivity (10⁻⁶ ppm). -4 ~10 -3 It exhibits good stability to lithium metal (S / cm). However, pure-phase LLZO typically exists as a tetragonal phase at room temperature. Although the cubic phase can be stabilized by elemental doping (such as Ta, Al, Ga, etc.) in traditional techniques, the doping efficiency is low during the preparation process, resulting in a low cubic phase content in the product. Summary of the Invention

[0003] Therefore, it is necessary to provide doped lithium lanthanum zirconium oxide materials with high cubic LLZO content, their preparation methods, and batteries.

[0004] In a first aspect, this application provides a method for preparing a lithium-doped lanthanum zirconium oxide material, the method comprising:

[0005] A first mixture is obtained by mixing and ball milling a lithium source, a lanthanum source, a zirconium source, a doped M source, and an organic solvent, wherein the volume average particle size D50 of the particles in the first mixture is ≤500nm.

[0006] The first mixture was spray-dried to obtain precursor powder, and the precursor powder was sintered to prepare lithium-lanthanum-zirconium oxide material.

[0007] In some embodiments, the preparation method satisfies at least one of the following conditions:

[0008] (1) The molar ratio of lithium in the lithium source, lanthanum in the lanthanum source, zirconium in the zirconium source and M in the doped M source is (7.35-1.05x):3:2:x ~ (7.7-1.1x):3:2:x, x=0.3~0.5;

[0009] (2) The M element in the doped M source includes at least one of gallium, tantalum, niobium, zinc, aluminum, tungsten and molybdenum;

[0010] (3) Organic solvents include at least one of ethanol, isopropanol, acetonitrile and acetone;

[0011] (4) The lithium source includes at least one of lithium carbonate, lithium hydroxide and lithium acetate;

[0012] (5) The lanthanum source includes at least one of lanthanum oxide and lanthanum nitrate;

[0013] (6) The zirconium source includes at least one of zirconium oxide and butyl zirconate;

[0014] (7) The doped M source includes at least one of nitrate containing M and oxide containing M.

[0015] In some implementations, the ball mill satisfies at least one of the following conditions:

[0016] (1) The volume filling rate of the ball mill media is 75%~90%, and the diameter of the ball mill media is 0.1mm~1.0mm;

[0017] (2) The ball milling speed is 2200rpm~2400rpm and the ball milling time is 3h~10h.

[0018] In some embodiments, the first mixture satisfies at least one of the following conditions:

[0019] (1) The solid content of the first mixture is 20%~40%;

[0020] (2) The volume average particle size D50 of the particles in the first mixture is 300nm~500nm.

[0021] In some embodiments, spray drying satisfies at least one of the following conditions:

[0022] (1) The inlet temperature of the spray dryer is 80℃~120℃, the outlet temperature is 30℃~50℃, and the atomization pressure is 0.2MPa~0.4MPa;

[0023] (2) The volume average particle size D50 of the precursor powder is 400nm~500nm.

[0024] In some embodiments, the sintering temperature is 800℃~1100℃, the holding time is 6h~24h, the heating rate is 3℃ / min~5℃ / min, and the cooling rate is 1℃ / min~3℃ / min.

[0025] In some embodiments, the sintering temperature is 800℃~900℃ and the holding time is 12h~24h; or, the sintering temperature is 900℃~1000℃ and the holding time is 10h~12h; or, the sintering temperature is 1000℃~1100℃ and the holding time is 6h~12h.

[0026] In some embodiments, the preparation method also satisfies at least one of the following conditions:

[0027] (1) The sintered lithium-lanthanum-zirconium oxide material is crushed;

[0028] (2) The cubic phase of the lithium lanthanum zirconium oxide material contained in the lithium lanthanum zirconium oxide material accounts for ≥95% of the mass.

[0029] Secondly, this application also provides a lithium-doped lanthanum zirconium oxide material, which is prepared by the method for preparing lithium-doped lanthanum zirconium oxide material as described in the first aspect.

[0030] Thirdly, this application also provides a battery, which includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the positive electrode and the negative electrode, and the solid electrolyte layer includes a lithium-doped lanthanum zirconium oxide material as described in the second aspect.

[0031] Compared with traditional technologies, this application has at least the following beneficial effects:

[0032] This application employs wet ball milling of the raw materials using organic solvents to avoid hydrolysis of the lanthanum source, which would otherwise form lanthanum hydroxide containing water of crystallization and hydroxyl groups. This effectively reduces side reactions during sintering and minimizes lithium volatilization and loss, maintaining the stoichiometry of the raw materials after ball milling. Simultaneously, this application controls the particle size after ball milling and, combined with spray drying, forms a precursor powder with uniform composition, ensuring efficient and uniform dispersion of dopant elements in the material. This effectively improves sintering activity and facilitates the formation of dense and high-purity cubic LLZO. Therefore, the preparation process of this application exhibits good repeatability and is suitable for large-scale production. Attached Figure Description

[0033] Figure 1 The image shows the XRD pattern of the lithium-doped lanthanum zirconium oxide material prepared in Example 1 of this application. Detailed Implementation

[0034] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are only for illustrating the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. In addition, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0036] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0037] In this application, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first aspect," "second aspect," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0038] In traditional techniques, water is used as a solvent for wet ball milling. Lanthanum ions in the lanthanum source hydrolyze to form La(OH)3, potentially accompanied by the formation of some basic carbonates. This application reveals that after lanthanum ion hydrolysis and drying, crystal water and hydroxyl groups are introduced into the raw material. This leads to the volatilization and high-pressure release of water vapor during sintering, easily causing product pulverization. Simultaneously, the water vapor promotes the volatilization and loss of lithium compounds, resulting in severe lithium deficiency in the product. Furthermore, La(OH)3 decomposes at 400℃~600℃, reacting with lithium and zirconium ions to form the La2Zr2O7 pyrochlore phase and impurities such as lithium lanthanum oxide, affecting the content of cubic LLZO in the product. Moreover, variations in slurry humidity, exposure time, and environmental parameters result in different degrees of lanthanum ion hydrolysis in each batch of raw material, leading to inconsistent purity across different batches.

[0039] The first aspect of this application provides a method for preparing a lithium-doped lanthanum zirconium oxide material, the method comprising:

[0040] A first mixture is obtained by mixing and ball milling a lithium source, a lanthanum source, a zirconium source, a doped M source, and an organic solvent, wherein the volume average particle size D50 of the particles in the first mixture is ≤500nm.

[0041] The first mixture was spray-dried to obtain precursor powder, and the precursor powder was sintered to prepare lithium-lanthanum-zirconium oxide material.

[0042] The volume average particle size D50 of the particles in the first mixture can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, or 500nm. It can be selected as 300nm~500nm.

[0043] This application controls the particle size of the material after ball milling as described above, so that the particles in the slurry are fully ground and evenly distributed, thereby ensuring sintering activity and promoting the formation of cubic phase LLZO.

[0044] Understandably, the raw materials can be weighed according to the atomic molar ratio of the metal elements in the lithium-lanthanum-zirconium oxide doped material. Since lithium will volatilize and be lost during sintering, a slight excess of lithium source can be added to the raw materials. For example, the amount of lithium added to the lithium source is 1.05 to 1.10 times the amount of lithium in the lithium-lanthanum-zirconium oxide doped material, and can be selected as 1.05, 1.06, 1.07, 1.08, 1.09, or 1.10 times. In some embodiments, the molar ratio of lithium in the lithium source, lanthanum in the lanthanum source, zirconium in the zirconium source, and M in the doped M source is (7.35-1.05x):3:2:x ~ (7.7-1.1x):3:2:x, where x = 0.3 to 0.5. Where x can be 0.30, 0.32, 0.34, 0.36, 0.38, 0.40, 0.42, 0.44, 0.46, 0.48, or 0.50. Optionally, the chemical formula of the lithium-doped lanthanum zirconium oxide material is Li. （7-x） M x La3Zr2O 12 Where x = 0.3~0.5, and M includes at least one of gallium, tantalum, niobium, zinc, aluminum, tungsten and molybdenum.

[0045] This application controls the amount of M-doped material as described above. By doping the material with ions of higher valence states and introducing lithium vacancies, the ordered arrangement of lithium ions in tetragonal LLZO is disrupted, thereby effectively stabilizing the cubic phase structure with high electrical conductivity. If the doping amount of M is relatively low, the lithium vacancy concentration may be relatively low, which may not be able to suppress the ordered arrangement of lithium ions in LLZO, resulting in poor stability of the cubic phase structure and easy formation of tetragonal phases or other impurity phases. If the doping amount of M is relatively high, the lithium vacancy concentration may be relatively high, causing severe lithium sublattice vacancies, lattice framework distortion or local collapse, leading to XRD diffraction peak broadening and abnormal shift, forming an impurity phase rich in doped element M.

[0046] In some embodiments, the element M in the doping source includes at least one selected from gallium, tantalum, niobium, zinc, aluminum, tungsten, and molybdenum. Gallium is optional. The doping element selected above in this application can effectively stabilize the cubic phase crystal structure of LLZO and improve the ionic conductivity of the material.

[0047] In some embodiments, the organic solvent includes at least one selected from ethanol, isopropanol, acetonitrile, and acetone. The use of organic solvents in this application avoids the hydrolysis of lanthanum ions in the lanthanum source, which not only reduces the volatilization and loss of lithium but also minimizes side reactions during sintering, ensuring the formation of cubic LLZO in the product.

[0048] In some embodiments, the lithium source includes at least one of lithium carbonate, lithium hydroxide, and lithium acetate. The lanthanum source includes at least one of lanthanum oxide and lanthanum nitrate. The zirconium source includes at least one of zirconium oxide and butyl zirconate. The doped M source includes at least one of a nitrate containing element M and an oxide containing element M. Taking gallium as an example, the doped M source includes at least one of gallium oxide and gallium nitrate. It is understood that materials that are prone to moisture absorption (such as lithium hydroxide) should be dehumidified to avoid affecting the stoichiometry of elements during weighing, thereby affecting the sintering process.

[0049] In some embodiments, the volumetric filling rate of the grinding media in the ball mill is 75% to 90%, for example, it can be 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%. The diameter of the grinding media is 0.1 mm to 1.0 mm, for example, it can be 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm. Zirconia balls can be used as the grinding media.

[0050] In some embodiments, the ball milling speed is 2200 rpm to 2400 rpm, for example, 2200 rpm, 2250 rpm, 2300 rpm, 2350 rpm or 2400 rpm. The ball milling time is 3h to 10h, for example, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h.

[0051] This application controls the process parameters of wet ball milling as described above, thereby ensuring that the raw material is ball-milled into particles with a volume average particle size D50≤500nm, thus ensuring the uniformity of mixing of lithium source, lanthanum source, zirconium source and doped M source, and ensuring that the doping element M is efficiently and uniformly doped into LLZO during sintering, so as to stabilize the cubic phase crystal form of LLZO.

[0052] In some embodiments, the solid content of the first mixture is 20% to 40%, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%.

[0053] In some embodiments, the inlet temperature of the spray dryer is 80°C to 120°C, for example, it can be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C. The outlet temperature is 30°C to 50°C, for example, it can be 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C, 46°C, 48°C, or 50°C. The atomization pressure is 0.2MPa to 0.4MPa, for example, it can be 0.20MPa, 0.22MPa, 0.24MPa, 0.26MPa, 0.28MPa, 0.30MPa, 0.32MPa, 0.34MPa, 0.36MPa, 0.38MPa, or 0.40MPa.

[0054] This application controls the spray drying process parameters as described above to ensure the formation of spherical precursor powder with good flowability after drying, avoiding component segregation and resulting in uniform material composition and good sintering activity. If atomization is insufficient during spray drying, problems such as coarse droplets may occur, leading to relatively large powder particle size and a wide particle size distribution, which affects sintering activity.

[0055] In some embodiments, the volume average particle size D50 of the precursor powder is 400nm~500nm, for example, it can be 400nm, 410nm, 420nm, 430nm, 440nm, 450nm, 460nm, 470nm, 480nm, 490nm or 500nm.

[0056] In some embodiments, the sintering temperature is 800℃~1100℃, for example, it can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃, 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, or 1100℃. The holding time is 6h~24h, for example, it can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, or 24h.

[0057] Optionally, the sintering temperature is 800℃~900℃ and the holding time is 12h~24h; or, the sintering temperature is 900℃~1000℃ and the holding time is 10h~12h; or, the sintering temperature is 1000℃~1100℃ and the holding time is 6h~12h.

[0058] This application selects the sintering temperature and time as described above. Through high-temperature, short-time sintering, cubic LLZO is rapidly formed, effectively preventing excessive lithium volatilization, ensuring sintering purity, and shortening production time. If the sintering temperature is relatively high or the time is relatively long, excessive lithium volatilization may cause lithium deficiency in the material, leading to excessive impurity phases and affecting product purity. If the sintering temperature is relatively low or the time is relatively short, incomplete crystallization may prevent the tetragonal LLZO from fully transforming into a cubic phase structure, and LZO (La2Zr2O7) impurity phases may also form, affecting the formation of cubic LLZO.

[0059] In some embodiments, the sintering heating rate is 3°C / min to 5°C / min, for example, it can be 3.0°C / min, 3.5°C / min, 4.0°C / min, 4.5°C / min, or 5.0°C / min. The sintering atmosphere can be an oxygen-containing atmosphere or an inert atmosphere. The oxygen-containing atmosphere can be an air atmosphere, and the inert atmosphere refers to an atmosphere that does not react with the raw materials, such as an argon atmosphere.

[0060] In some embodiments, the cooling rate of the material after sintering is 1°C / min to 3°C / min, for example, 1.0°C / min, 1.5°C / min, 2.0°C / min, 2.5°C / min, or 3.0°C / min. The temperature of the material after cooling can be room temperature, for example, 15°C to 35°C. The cooling rate selected above in this application avoids the problem of thermal stress release cracking caused by rapid cooling, thus ensuring the density of the material.

[0061] In some embodiments, the sintered lithium lanthanum zirconium oxide material is subjected to a crushing process to meet usage requirements. For example, the crushing process includes wet ball milling and drying of the sintered lithium lanthanum zirconium oxide material. The wet ball milling can use an organic solvent, with a ball milling media volume filling rate of 75%–90% and a ball milling media diameter of 0.1 mm–1.0 mm; the ball milling speed is 2200 rpm–2400 rpm, and the time is 3 h–10 h. The drying process can employ spray drying, with an inlet temperature of 80℃–120℃, an outlet temperature of 30℃–50℃, and an atomization pressure of 0.2 MPa–0.4 MPa.

[0062] In some embodiments, the cubic phase doped lithium lanthanum zirconium oxide material contains ≥95% by mass, for example, 95.0%, 95.5%, 96.0%, 96.5%, 97.0%, 97.5%, 98.0%, 98.5%, 99.0%, 99.5%, or 100.0%.

[0063] Exemplary, a method for preparing the above-mentioned lithium-lanthanum-zirconium-oxygen doped material is provided, comprising the following steps:

[0064] A lithium source, lanthanum source, zirconium source, doped M source, and organic solvent were mixed and ball-milled using ball milling media with a diameter of 0.1 mm to 1.0 mm. The volumetric filling rate of the ball milling media was 75% to 90%, the ball milling speed was 2200 rpm to 2400 rpm, and the ball milling time was 3 h to 10 h. After ball milling, a first mixture with a solid content of 20% to 40% was obtained, and the volume average particle size D50 of the particles in the first mixture was ≤500 nm.

[0065] The first mixture was spray-dried to obtain precursor powder with a volume average particle size D50 of 400nm~500nm. The inlet temperature of the spray dryer was 80℃~120℃, the outlet temperature was 30℃~50℃, and the atomization pressure was 0.2MPa~0.4MPa.

[0066] The precursor powder was heated to 800℃~1100℃ at a rate of 3℃ / min~5℃ / min and sintered for 6h~24h, then cooled to room temperature at a rate of 1℃ / min~3℃ / min to prepare lithium-doped lanthanum zirconium oxide material with the chemical formula Li. （7-x） M x La3Zr2O 12 x = 0.3~0.5.

[0067] The second aspect of this application also provides a lithium lanthanum zirconium oxide doped material, which is prepared by the method for preparing lithium lanthanum zirconium oxide doped material as described in the first aspect.

[0068] A third aspect of this application also provides a battery, which includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the positive electrode and the negative electrode, and the solid electrolyte layer includes a lithium-doped lanthanum zirconium oxide material as described in the second aspect.

[0069] In some embodiments, the solid electrolyte layer may be formed by hot pressing of a material containing the aforementioned doped lithium lanthanum zirconium oxide.

[0070] In some embodiments, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector. The positive current collector may be an aluminum foil. The positive active material may be at least one of lithium cobalt oxide, lithium manganese oxide, nickel-manganese materials, lithium iron phosphate, and nickel-cobalt-manganese ternary materials.

[0071] The negative electrode includes a negative electrode current collector and a layer of negative electrode active material disposed on at least one surface of the negative electrode current collector. The negative electrode current collector may be copper foil. The negative electrode active material may be at least one of lithium metal, hard carbon, and soft carbon.

[0072] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0073] Example 1

[0074] S1. Lithium carbonate, lanthanum nitrate, zirconium oxide, and gallium oxide were weighed according to a Li:La:Zr:Ga molar ratio of 6.93:3:2:0.4. The weighed raw materials were mixed with ethanol and then wet-milled using zirconium oxide balls with a diameter of 0.5 mm. The volumetric filling rate of the zirconium oxide balls was 80%, the milling speed was 2300 rpm, and the milling time was 6 hours. After milling, a first mixture with a solid content of 30% was obtained, and the volume average particle size (D50) of the particles in the first mixture was 400 nm.

[0075] The first mixture was spray-dried to obtain a precursor powder with a volume average particle size D50 of 400 nm. The inlet temperature of the spray dryer was 100℃, the outlet temperature was 40℃, and the atomization pressure was 0.3 MPa.

[0076] The precursor powder was heated to 900℃ and sintered for 12 hours at a rate of 4℃ / min, and then cooled to room temperature at a rate of 2℃ / min to prepare lithium lanthanum zirconium oxide material.

[0077] The sintered lithium-lanthanum-zirconium oxide material obtained above was subjected to wet ball milling and spray drying. The process parameters for both wet ball milling and spray drying were the same as those for the raw material. The resulting lithium-lanthanum-zirconium oxide material had the chemical formula Li. 6.6 Ga 0.4 La3Zr2O 12 Its XRD pattern is as follows Figure 1 As shown.

[0078] Example 2

[0079] S1. Lithium hydroxide, lanthanum oxide, butyl zirconate, and gallium nitrate were weighed according to a Li:La:Zr:Ga molar ratio of 7.37:3:2:0.3. The weighed raw materials were mixed with ethanol and then wet-milled using 1mm diameter zirconia balls. The zirconia ball volume filling rate was 75%, the milling speed was 2400 rpm, and the milling time was 10 hours. After milling, a first mixture with a solid content of 20% was obtained, and the volume average particle size D50 of the particles in the first mixture was 500 nm.

[0080] The first mixture was spray-dried to obtain a precursor powder with a volume average particle size D50 of 500 nm. The inlet temperature of the spray dryer was 120 °C, the outlet temperature was 50 °C, and the atomization pressure was 0.2 MPa.

[0081] The precursor powder was heated to 1100℃ and sintered for 6 hours at a rate of 3℃ / min, and then cooled to room temperature at a rate of 2℃ / min to prepare lithium lanthanum zirconium oxide material.

[0082] The sintered lithium-lanthanum-zirconium oxide material obtained above was subjected to wet ball milling and spray drying. The process parameters for both wet ball milling and spray drying were the same as those for the raw material. The resulting lithium-lanthanum-zirconium oxide material had the chemical formula Li. 6.7 Ga 0.3 La3Zr2O 12 .

[0083] Example 3

[0084] S1. Lithium carbonate, lanthanum oxide, butyl zirconate, and gallium oxide were weighed according to a Li:La:Zr:Ga molar ratio of 7:3:2:0.5. The weighed raw materials were mixed with isopropanol and then wet-milled using 1mm diameter zirconia balls. The zirconia ball volume filling rate was 75%, the milling speed was 2400 rpm, and the milling time was 10 hours. After milling, a first mixture with a solid content of 20% was obtained, and the volume average particle size D50 of the particles in the first mixture was 500 nm.

[0085] The first mixture was spray-dried to obtain a precursor powder with a volume average particle size D50 of 500 nm. The inlet temperature of the spray dryer was 120 °C, the outlet temperature was 50 °C, and the atomization pressure was 0.2 MPa.

[0086] The precursor powder was heated to 1100℃ and sintered for 6 hours at a rate of 3℃ / min, and then cooled to room temperature at a rate of 2℃ / min to prepare lithium lanthanum zirconium oxide material.

[0087] The sintered lithium-lanthanum-zirconium oxide material obtained above was subjected to wet ball milling and spray drying. The process parameters for both wet ball milling and spray drying were the same as those for the raw material. The resulting lithium-lanthanum-zirconium oxide material had the chemical formula Li. 6.5 Ga 0.5 La3Zr2O 12 .

[0088] Example 4

[0089] The lithium-lanthanum zirconium oxide material was prepared according to the method in Example 1, except that the sintering temperature was 850°C and the sintering time was 18 hours.

[0090] Example 5

[0091] The lithium-lanthanum zirconium oxide material was prepared according to the method in Example 1, except that the sintering temperature was 950°C and the sintering time was 11 hours.

[0092] Example 6

[0093] The lithium-lanthanum zirconium oxide material was prepared according to the method in Example 1, except that the sintering temperature was 1050°C and the sintering time was 9 hours.

[0094] Example 7

[0095] The lithium-doped lanthanum zirconium oxide material was prepared according to the method in Example 1, except that the sintering temperature was 1150°C.

[0096] Example 8

[0097] The lithium-doped lanthanum zirconium oxide material was prepared according to the method in Example 1, except that the sintering time was 8 hours.

[0098] Example 9

[0099] The lithium-lanthanum zirconium oxide material was prepared according to the method in Example 1, except that lithium carbonate, lanthanum nitrate, zirconium oxide and gallium oxide were weighed according to the molar ratio of Li:La:Zr:Ga of 7.14:3:2:0.2.

[0100] Example 10

[0101] The lithium-lanthanum zirconium oxide material was prepared according to the method in Example 1, except that lithium carbonate, lanthanum nitrate, zirconium oxide and gallium oxide were weighed according to the molar ratio of Li:La:Zr:Ga of 6.72:3:2:0.6.

[0102] Comparative Example 1

[0103] The lithium-doped lanthanum zirconium oxide material was prepared according to the method of Example 1, except that ethanol was replaced with water.

[0104] Comparative Example 2

[0105] The lithium-lanthanum zirconium oxide material was prepared according to the method of Example 1, except that the ball milling parameters were adjusted so that the volume average particle size D50 of the particles in the first mixture was about 1000 nm.

[0106] Comparative Example 3

[0107] The lithium lanthanum zirconium oxide material was prepared according to the method of Example 1, except that spray drying was replaced by oven drying. The solvent was first evaporated at a drying temperature of 80°C, and then dried at a drying temperature of 100°C for 10 hours.

[0108] The lithium-lanthanum zirconium oxide (LLZO) doped materials prepared in the above examples and comparative examples were characterized by XRD, and the mass purity of the cubic phase in the materials was analyzed. The analytical methods included: X-ray diffraction (XRD) was used to analyze the phase composition of the obtained LLZO powder, with a scanning range of 5° to 90° and a step size of 0.01°; the Rietveld full-spectrum refinement method was used to perform quantitative phase analysis on the diffraction data, and the mass fraction of the cubic phase was calculated. The test results are shown in Table 1.

[0109] Table 1

[0110]

[0111] As can be seen from the table above:

[0112] In Examples 1-8, the purity of the cubic phase was higher than that of Comparative Examples 1-3. Specifically, the sintering temperature of Example 7 was relatively high, resulting in significant lithium volatilization and the presence of a large amount of lithium-deficient impurity phase La₂Zr₂O₇, thus its purity was lower than that of Example 1. The sintering time of Example 8 was relatively short, leading to insufficient reaction time and a relatively high content of tetragonal and impurity phases, thus its purity was lower than that of Example 1. Example 9 had a low dopant content, possibly due to a low lithium vacancy concentration, resulting in poor cubic phase stability and the presence of tetragonal and other impurity phases. Example 10 had a relatively high dopant content, possibly due to a high lithium vacancy concentration, causing lattice distortion and local collapse, forming an impurity phase rich in dopant element M.

[0113] Comparative Example 1 used water for ball milling, which caused lanthanum to hydrolyze and form lanthanum hydroxide. This increased side reactions during sintering and resulted in a porous structure, significantly reducing the content of cubic LLZO. Furthermore, the purity of cubic LLZO varied considerably across different experimental batches. In Comparative Example 2, the ball-milled particles were larger, resulting in poor interparticle contact, hindered reaction kinetics, mass transfer difficulties, and incomplete local reactions, thus affecting LLZO formation. In Comparative Example 3, a conventional drying method was used. The prolonged settling time during drying easily led to component segregation, which in turn formed a reaction barrier during sintering, affecting the formation of cubic LLZO.

[0114] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for preparing a lithium-doped lanthanum zirconium oxide material, characterized in that, The preparation method includes: A first mixture is obtained by mixing and ball milling a lithium source, a lanthanum source, a zirconium source, a doped M source, and an organic solvent, wherein the volume average particle size D50 of the particles in the first mixture is ≤500nm. The first mixture was spray-dried to obtain precursor powder, and the precursor powder was sintered to prepare the doped lithium lanthanum zirconium oxide material.

2. The preparation method of the lithium-doped lanthanum zirconium oxide material as described in claim 1, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The molar ratio of lithium in the lithium source, lanthanum in the lanthanum source, zirconium in the zirconium source and M in the doped M source is (7.35-1.05x):3:2:x ~ (7.7-1.1x):3:2:x, where x = 0.3~0.5; (2) The M element in the doped M source includes at least one of gallium, tantalum, niobium, zinc, aluminum, tungsten and molybdenum; (3) The organic solvent includes at least one of ethanol, isopropanol, acetonitrile and acetone; (4) The lithium source includes at least one of lithium carbonate, lithium hydroxide and lithium acetate; (5) The lanthanum source includes at least one of lanthanum oxide and lanthanum nitrate; (6) The zirconium source includes at least one of zirconium oxide and butyl zirconate; (7) The doped M source includes at least one of a nitrate containing the M element and an oxide containing the M element.

3. The method for preparing the lithium-doped lanthanum zirconium oxide material as described in claim 1, characterized in that, The ball mill satisfies at least one of the following conditions: (1) The ball milling media has a volume filling rate of 75%~90% and a diameter of 0.1mm~1.0mm; (2) The rotation speed of the ball mill is 2200 rpm to 2400 rpm, and the ball milling time is 3 h to 10 h.

4. The preparation method of the lithium-doped lanthanum zirconium oxide material as described in claim 1, characterized in that, The first mixture satisfies at least one of the following conditions: (1) The solid content of the first mixture is 20%~40%; (2) The volume average particle size D50 of the particles in the first mixture is 300nm~500nm.

5. The method for preparing the lithium-doped lanthanum zirconium oxide material as described in claim 1, characterized in that, The spray drying satisfies at least one of the following conditions: (1) The inlet temperature of the spray dryer is 80℃~120℃, the outlet temperature is 30℃~50℃, and the atomization pressure is 0.2MPa~0.4MPa; (2) The volume average particle size D50 of the precursor powder is 400nm~500nm.

6. The method for preparing the lithium-doped lanthanum zirconium oxide material as described in claim 1, characterized in that, The sintering temperature is 800℃~1100℃, the holding time is 6h~24h, the heating rate is 3℃ / min~5℃ / min, and the cooling rate is 1℃ / min~3℃ / min.

7. The method for preparing the lithium-doped lanthanum zirconium oxide material as described in claim 6, characterized in that, The sintering temperature is 800℃~900℃, and the holding time is 12h~24h; or, the sintering temperature is 900℃~1000℃, and the holding time is 10h~12h; or, the sintering temperature is 1000℃~1100℃, and the holding time is 6h~12h.

8. The method for preparing the lithium-doped lanthanum zirconium oxide material according to any one of claims 1-7, characterized in that, The preparation method also satisfies at least one of the following conditions: (1) The sintered lithium-lanthanum-zirconium-oxygen material is crushed; (2) The cubic phase doped lithium lanthanum zirconium oxide material contains ≥95% of the mass of the doped lithium lanthanum zirconium oxide material.

9. A lithium-doped lanthanum zirconium oxide material, characterized in that, The doped lithium lanthanum zirconium oxide material is prepared by the method described in any one of claims 1-8.

10. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is disposed between the positive electrode and the negative electrode, and the solid electrolyte layer includes the lithium-doped lanthanum zirconium oxide material as described in claim 9.

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