Solid-state electrolyte material and method for producing the same

Abstract

The application discloses a solid electrolyte material, and has the chemical formula: Li 7‑ 3y Al y La3Zr 8‑5x Nb x O 12 Wherein, 0.1<=x<=0.4, 0.1<=y<0.2. The solid electrolyte material and the preparation method thereof are characterized in that Al and Nb are doped, the preparation method is solid phase sintering, the chemical proportion is adjusted, lithium is excessive and lanthanum is a little, a pure cubic phase lithium lanthanum zirconium oxygen solid electrolyte is obtained by one-step sintering, and the diffraction peak of a lanthanum oxide impurity phase is eliminated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery materials, in particular to a solid electrolyte material and a preparation method thereof. BACKGROUND

[0002] At present, most of the lithium ion batteries widely used in the market use liquid or gel electrolytes, both of which have the common characteristics of using flammable and explosive organic substances and having certain fluidity, which brings serious safety hazards to the use of lithium ion batteries.

[0003] Using solid electrolyte is one of the best solutions to the above-mentioned safety hazards. Among the currently common solid electrolyte materials, lithium lanthanum zirconium oxide (LLZO) with a cubic garnet structure is a material with great application prospect. Compared with other solid electrolyte materials, LLZO has good thermal stability and electrochemical stability, and has more advantages in the cycle life and reliability of the battery. Among the existing methods for preparing lithium lanthanum zirconium oxide, the solid phase sintering method has a simple process flow and is easy to realize quantitative production. However, lithium lanthanum zirconium oxide is very difficult to synthesize pure cubic phase powder by solid phase synthesis due to its harsh synthesis temperature and synthesis conditions; at the same time, the current solid phase synthesis steps are more, and the lithium lanthanum zirconium oxide powder can be prepared only after long-time repeated high-temperature sintering or complicated precursor pretreatment in the early stage; the cost is high and the sintering steps are complicated, and pure cubic phase lithium lanthanum zirconium oxide powder cannot be prepared by one-step sintering. On the other hand, the lithium lanthanum zirconium oxide powder obtained by the existing sintering preparation has a mixed phase diffraction peak of lanthanum oxide; the existence of the mixed phase will affect the ionic conductivity and affect the electrochemical performance. SUMMARY

[0004] The present application provides an aluminum element and niobium element double-doped solid electrolyte material and a preparation method thereof to solve the problems that the existing solid phase method for preparing lithium lanthanum zirconium oxide has complicated steps and it is difficult to prepare pure phase lithium lanthanum zirconium oxide powder.

[0005] In order to solve the above technical problems, the present application provides a solid electrolyte material, the chemical formula of which is: Li 7-3y Al y La3Zr 8-5x Nb x O 12 , wherein 0.1≤x≤0.4, 0.1≤y<0.2.

[0006] In a feasible implementation manner, the solid electrolyte material has a cubic phase crystal structure.

[0007] Correspondingly, the present application also provides a preparation method of the solid electrolyte material as described in any one of the above, comprising the following steps: according to the chemical formula Li 7-3y Aly La3Zr 8-5x Nb x O 12 The raw materials including a lithium source material, a lanthanum source material, a zirconium source material, an aluminum source material and a niobium source material are weighed according to the stoichiometric ratio of each element, wherein the lanthanum source is less than 0.2%-1%, and the lithium source is more than 5%-13%; the raw materials are mixed to obtain a mixed product; the mixed product is subjected to solid phase sintering to obtain a sintered product; and the sintered product is subjected to crushing and depolymerization to obtain a target product, wherein the average particle size of the target product is 100 nm-300 nm.

[0008] In a feasible implementation, the mixing is achieved by dry mixing.

[0009] In a feasible implementation, the solid phase sintering includes one-time sintering, the sintering temperature is 1000-1200℃, and the sintering time is 5-20 h.

[0010] In a feasible implementation, the crushing and depolymerization includes: primary crushing of the sintered product to obtain a first crushed product, wherein the particle size of the first crushed product is 10-50 μm; secondary crushing of the first crushed product to obtain a second crushed product, wherein the particle size of the second crushed product is less than 3 μm; tertiary crushing of the second crushed product to obtain a third crushed product, wherein the particle size of the third crushed product is less than 300 nm; drying of the third crushed product to obtain a candidate target product, wherein the drying temperature is 100-200℃, and the drying time is 15-48 h; and depolymerization of the candidate target product to obtain the target product.

[0011] In a feasible implementation, the tertiary crushing includes sand milling, and the sand milling solvent includes alcohol.

[0012] In a feasible implementation, the depolymerization includes crushing the candidate target product into the target product by a disc airflow mill.

[0013] In a feasible implementation, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate or lithium acetate; the lanthanum source includes lanthanum oxide, lanthanum hydroxide or lanthanum nitrate; the zirconium source includes zirconium oxide, zirconium hydroxide, zirconium nitrate or zirconium carbonate; the aluminum source is aluminum oxide; and the niobium source is niobium oxide.

[0014] The present application has the following advantages:

[0015] The solid electrolyte material and its preparation method provided by this invention involve Al and Nb dual doping and solid-state sintering. The chemical ratio is adjusted to have excess lithium and a small amount of lanthanum. A pure cubic phase lithium lanthanum zirconium oxide solid electrolyte is successfully obtained by one-step sintering, eliminating the diffraction peaks of lanthanum oxide impurity phase. Attached Figure Description

[0016] Figure 1 This is the X-ray diffraction (XRD) pattern of the lithium lanthanum zirconium oxide material in Example 1 of this invention;

[0017] Figure 2 This is the X-ray diffraction (XRD) pattern of the lithium lanthanum zirconium oxide material in Example 2 of this invention;

[0018] Figure 3 These are the X-ray diffraction (XRD) patterns of the lithium lanthanum zirconium oxide materials in Examples 3 and 4 of this invention;

[0019] Figure 4 This is a scanning electron microscope (SEM) image of the material in Embodiment 1 of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0021] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] This application provides a solid electrolyte material. The chemical formula of the solid electrolyte material is: Li 7- 3y Al y La3Zr 8-5x Nb x O 12wherein, 0.1≤x≤0.4, 0.1≤y<0.2. The solid electrolyte material has a cubic phase crystal structure and an ellipsoidal morphology. The solid electrolyte material with the cubic phase crystal structure has better conductivity, and can be prepared by the subsequent preparation method, which is simple and easy to operate. The solid electrolyte material has a light yellow color and a pH of 11-12. The solid electrolyte material provided in the present application is doped with aluminum and niobium, can be prepared by one-step sintering of solid phase sintering, and the prepared product has no lanthanum oxide impurity diffraction peak.

[0023] Another aspect of the present application provides a preparation method of the above solid electrolyte material. The preparation method comprises the following steps:

[0024] According to the chemical formula Li 7-3y Al y La3Zr 8-5x Nb x O 12 The raw materials are weighed according to the stoichiometric ratio of each element. The raw materials include: lithium source material, lanthanum source material, zirconium source material, aluminum source material and niobium source material. Among them, the amount of lanthanum source is 0.2%-1%, and the amount of lithium source is 5%-13% in excess. During preparation, the above raw materials are mixed to obtain a mixed product, the mixed product is subjected to solid phase sintering to obtain a sintered product, and finally the sintered product is subjected to crushing and depolymerization to obtain a target product. The target product is the above-mentioned solid electrolyte material, and the average particle size is 100-300 nm.

[0025] In one possible implementation, the lithium source in the raw materials can include lithium carbonate, lithium hydroxide, lithium nitrate or lithium acetate. The lanthanum source can include lanthanum oxide, lanthanum hydroxide or lanthanum nitrate. The zirconium source can include zirconium oxide, zirconium hydroxide, zirconium nitrate or zirconium carbonate. Alternatively or preferably, the lithium source can be lithium carbonate, the lanthanum source can be lanthanum oxide, the zirconium source can be zirconium oxide, the aluminum source can be aluminum oxide, and the niobium source can be niobium oxide.

[0026] In one possible way, when the raw materials are mixed to obtain a mixed product, the mixing can be realized by dry mixing method. For example, the raw materials can be loaded into a mixer for mixing. In one possible implementation, the rotation speed of the mixer can be greater than 1000 rpm, and the mixing time can be greater than 10 min. The mixer can be a double mixer, a high-speed mixer, an inclined mixer or a VC mixer, etc. For example, a high-speed mixer can be selected, the rotation speed can be 2000 rpm, and the mixing time can be 20 min.

[0027] In an available manner, when the mixed product is subjected to solid-phase sintering to obtain a sintered product, the solid-phase sintering can be one-time sintering, the sintering temperature is 1000-1200°C, and the sintering time is 5-20h. Alternatively or preferably, the sintering temperature can be 1000°C, and the sintering time is 10h. The conventional LLZO sintering temperature is generally above 1200 degrees, and the application can be synthesized at 1000°C by doping Al and Nb, thereby reducing the synthesis temperature and energy consumption.

[0028] In an available manner, when the sintered product is subjected to crushing and depolymerization to obtain a target product, the crushing and depolymerization can include: subjecting the sintered product to primary crushing to obtain a first crushed product, wherein the particle size of the first crushed product is 10-50μm; subjecting the first crushed product to secondary crushing to obtain a second crushed product, wherein the particle size of the second crushed product is less than 3μm; subjecting the second crushed product to tertiary crushing to obtain a third crushed product, wherein the particle size of the third crushed product is less than 300nm; drying the third crushed product to obtain a candidate target product, wherein the drying temperature is 100-200°C, and the drying time is 15-48h; and subjecting the candidate target product to depolymerization to obtain the target product.

[0029] In an available embodiment, when the primary crushing is performed, the primary crushing device can be a jaw crusher and a roller crusher. When the secondary crushing is performed, the secondary crushing device can be a disc airflow mill, and the air pressure of the disc airflow mill can be 8-10Mpa, and the feeding speed can be 1-2g / s.

[0030] In an available manner, when the second crushed product is subjected to tertiary crushing to obtain a third crushed product, the tertiary crushing can be sand milling, and the sand milling solvent can be alcohol, etc. In an available embodiment, the particle size of the sand milling zirconium beads during sand milling can be 0.2-0.3nm. Alternatively or preferably, the particle size of the sand milling zirconium beads can be 0.2nm. The sand milling time during sand milling can be 2-10h, and the sand milling speed can be 1000-2000rpm. Sand milling has better grinding effect, and on the basis of the previous crushing, sand milling can grind the particle size of the third crushed product to be finer.

[0031] In an available embodiment, the third crushed product after sand milling is a slurry, which needs to be dried, and the drying temperature can be 100-200°C, and the drying time can be 15-48h. Alternatively or preferably, the drying temperature can be 100°C, and the drying time can be 48h. The relatively high drying temperature and drying time can be beneficial to the volatilization of the sand milling solvent in the third crushed product, and also facilitate the subsequent depolymerization, so that the particle size of the target product, i.e., the solid-state electrolyte material, is more uniform.

[0032] In one possible manner, the depolymerization treatment of the candidate target product to obtain the target product solid electrolyte material can include: crushing the candidate target product into the target product by a disc airflow mill.

[0033] In order to further understand the present application, the solid electrolyte material and the preparation method thereof provided by the present application are described in detail below in combination with examples.

[0034] Example 1

[0035] The chemical formula of the solid electrolyte material is: Li 7-3y Al y La3Zr 8-5x Nb x O 12 , wherein (0.1≤x≤0.4, 0.1≤y<0.2). In this embodiment, the solid electrolyte material Li 7-3y Al y La3Zr 8-5x Nb x O 12 x is 0.4 and y is 0.1. That is, the chemical formula of the prepared solid electrolyte material is Li 6.4 Al 0.1 La3Zr6Nb 0.4 O 12 . The specific preparation method comprises:

[0036] According to the chemical formula Li 6.4 Al 0.1 La3Zr6Nb 0.4 O 12 , the lithium, lanthanum, zirconium, aluminum and niobium are weighed according to the metering ratio. Among them, the amount of lanthanum oxide in the chemical formula Li 6.4 Al 0.1 La3Zr6Nb 0.4 O 12 is less than the normal proportioning amount by 0.2%-1%, and in this embodiment, the amount is less than the normal proportioning amount by 0.5%. The amount of lithium carbonate is 5%-13% more than the normal proportioning amount, and in this embodiment, the amount is 10% more than the normal proportioning amount.

[0037] The above raw materials are mixed based on a dry mixing method to obtain a mixed product, and the dry mixing method does not change the particle size of the raw materials. Specifically, all the raw materials are loaded into a mixer for mixing. The mixer includes but is not limited to a double mixer, a high mixer, an inclined mixer, a VC mixer, etc.; the mixing speed is greater than 1000 rpm; and the mixing time is greater than 10 min. In this embodiment, a double mixer is selected as the mixer, the mixing speed is 1500 rpm, and the mixing time is 30 min.

[0038] The mixed product is subjected to solid phase sintering to obtain a sintered product, which is a pure cubic phase lithium lanthanum zirconium oxide solid electrolyte. The solid phase sintering is one-time sintering, the sintering temperature is 1000-1200°C, and the sintering time is 5-20h; in this embodiment, the sintering temperature is 1000°C, the sintering time is 10h, and the heating rate is 2°C / min. The sintering loading box is corundum, and the calcination is carried out in an air atmosphere; after natural cooling, a light yellow lithium lanthanum zirconium oxide powder is obtained. The pH is measured to be 11.5. Reference Figure 1 , Figure 1 is the XRD diffraction pattern of the lithium lanthanum zirconium oxide powder obtained by sintering in this embodiment. As shown in Figure 1 , the diffraction peaks of the lanthanum zirconium oxide solid electrolyte prepared in this embodiment all conform to the diffraction peaks of cubic lithium lanthanum zirconium oxide, and no impurity phase is generated. The results show that the pure phase lithium lanthanum zirconium oxide powder is successfully prepared by doping aluminum and niobium elements and one-time sintering in this embodiment.

[0039] The sintered product lithium lanthanum zirconium oxide material obtained by sintering is subjected to crushing and depolymerization treatment to obtain a target product solid electrolyte material. The target product solid electrolyte material is a nano-powder with an average particle size of 100-300nm. Solid electrolyte powder is usually used in the form of nano-powder, so the sintered product lithium lanthanum zirconium oxide powder prepared in this embodiment is prepared into nano-powder through a series of crushing and depolymerization means. Specifically, it includes:

[0040] The sintered product is subjected to primary crushing treatment by a crusher and a roller mill; a first crushed product powder with a particle size of 10-50μm is obtained.

[0041] The first crushed product powder after primary crushing is further crushed by a disc airflow mill to obtain a second crushed product powder with a particle size of less than 3μm. The air pressure of the disc airflow mill is 8-10Mpa, and the feeding speed is 1-2g / s; the smaller the particle size of the powder, the easier it is to reduce the particle size by sand milling; therefore, the particle size is made small enough by reducing the feeding speed and repeatedly crushing the disc airflow mill; and the foundation for sand milling into nano-particles is laid.

[0042] The second crushed product powder after disc airflow milling is subjected to sand milling, the sand milling solvent is alcohol, the sand milling zirconium bead particle size is 0.2-0.3mm, preferably 0.2mm, and the sand milling time is 2-10h; the sand milling speed is 1000-2000rpm; a third crushed product slurry with a particle size of less than 300nm is obtained. In this embodiment, the sand mill speed is 1000rpm, and the sand milling time is 3h; when the particle size is milled to 275nm, increasing the sand milling time or speed does not significantly change the particle size, and the limit particle size is reached; therefore, the sand milling is stopped when the particle size is milled to 275nm.

[0043] The third broken product sand slurry is dried at a drying temperature of 100-200℃ for 15-48h. In this embodiment, a vacuum oven is used for drying at a temperature of 200℃ for 24h.

[0044] The candidate target product agglomerates, which are agglomerated due to water evaporation after drying, are depolymerized. The candidate target product powder is broken into nanometer powder with an average particle size of 100-300nm by a disc airflow mill. The powder after drying is broken into powder by roller or ball milling, and then depolymerized by a disc airflow mill. The target product powder with a particle size of 285nm is obtained, which meets the application requirements since the particle size is less than 300nm. Figure 4 , Figure 4 is a scanning electron microscope (SEM) image of the solid electrolyte material in embodiment 1. It can be seen from Figure 4 that the target product solid electrolyte material powder is uniformly distributed nanometer powder with an elliptical shape under sufficient magnification. The elliptical shape is beneficial to the dispersion of the powder, reduces the friction between the powders, facilitates the flow of the powder, and makes the solid electrolyte material powder easier to disperse. The solid electrolyte material has good thermal stability and electrochemical stability, and the uniformly distributed elliptical nanometer powder is convenient for subsequent application and production, for example, the preparation of batteries. The battery prepared by using the solid electrolyte material has more advantages in terms of cycle life and reliability of the battery.

[0045] Embodiment 2

[0046] The chemical formula of the solid electrolyte material is: Li 7-3y Al y La3Zr 8-5x Nb x O 12 , wherein (0.1≤x≤0.4, 0.1≤y<0.2). In this embodiment, the solid electrolyte material Li 7-3y Al y La3Zr 8-5x Nb x O 12 has x=0.1 and y=0.19. That is, the chemical formula of the prepared solid electrolyte material is Li 6.43 Al 0.19 La3Zr 7.5 Nb 0.1 O 12 . The specific preparation method comprises:

[0047] According to the chemical formula Li 6.43 Al 0.19 La3Zr 7.5 Nb0.1 O 12 Lithium, lanthanum, zirconium, aluminum and niobium are weighed according to the stoichiometric ratio. Among them, the amount of lanthanum oxide is 0.2%-1% less than the normal stoichiometric ratio of Li 6.43 Al 0.19 La3Zr 7.5 Nb 0.1 O 12 1% in this embodiment, and the amount of lithium carbonate is 5%-13% more than the normal stoichiometric ratio of the above formula, 13% more in this embodiment.

[0048] The above raw materials are mixed based on the dry mixing method to obtain a mixed product, and the dry mixing method does not change the particle size of the raw materials. Specifically, all the raw materials are loaded into a mixer for mixing. The mixer includes but is not limited to a double mixer, a high mixer, an inclined mixer, a VC mixer, etc.; the mixing speed is greater than 1000 rpm; the mixing time is greater than 10 min. In this embodiment, a double mixer is selected as the mixer, the mixing speed is 2000 rpm, and the mixing time is 10 min.

[0049] The mixed product is subjected to solid phase sintering to obtain a sintered product, which is a pure cubic phase lithium lanthanum zirconium oxide solid electrolyte. The solid phase sintering is a one-time sintering, the sintering temperature is 1000-1200°C, and the sintering time is 5-20h; in this embodiment, the sintering temperature is 1200°C, the sintering time is 10h, and the heating rate is 2°C / min. The sintering loading crucible is corundum crucible, and calcination is carried out in air atmosphere; after natural cooling, a light yellow lithium lanthanum zirconium oxide powder is obtained. Figure 2 is the XRD diffraction pattern of the lithium lanthanum zirconium oxide powder sintered in this embodiment. As Figure 2 shown, the diffraction peaks of the lanthanum zirconium oxide solid electrolyte prepared in this embodiment all conform to the diffraction peaks of cubic lithium lanthanum zirconium oxide, and no impurity phase is generated.

[0050] Example 3

[0051] Different from Example 1, the value of x is 0.25 and the value of y is 0.15 in this embodiment, i.e., the prepared solid electrolyte material has the chemical formula Li 6.55 Al 0.15 La3Zr 6.75 Nb 0.25 O 12 . The specific preparation method includes:

[0052] According to the chemical formula Li 6.55 Al 0.15 La3Zr 6.75 Nb 0.25 O 12Lithium, lanthanum, zirconium, aluminum and niobium are weighed according to the metering ratio, and lithium hydroxide, lanthanum hydroxide, zirconium hydroxide and doped element aluminum oxide and niobium oxide are obtained. Among them, the chemical formula of lanthanum hydroxide is Li 6.55 Al 0.15 La3Zr 6.75 Nb 0.25 O 12 The normal ratio of lithium hydroxide is 5% more than the above chemical formula.

[0053] In this embodiment, the mixing machine is a high-speed mixer, the mixing speed is 2000 rpm, and the mixing time is 20 min. The sintering temperature is 1100℃, the sintering time is 15 h, and the heating rate is 2℃ / min. The sintering loading box is a corundum box, and the calcination is carried out in an air atmosphere; after natural cooling, the lithium lanthanum zirconium oxide powder with a light yellow color is obtained. Figure 3 The XRD diffraction pattern of the lithium lanthanum zirconium oxide powder sintered in Examples 3 and 4 is shown in Figure 2. Figure 3 As shown in Figure 2, the diffraction peaks of the lanthanum zirconium oxide solid electrolyte prepared in this embodiment are consistent with the diffraction peaks of cubic lithium lanthanum zirconium oxide, and no impurity phase is generated.

[0054] Example 4

[0055] The difference between this embodiment and Example 3 is that the lithium source is lithium nitrate, the lanthanum source is lanthanum nitrate, and the zirconium source is zirconium carbonate. In this embodiment, the mixing machine is an inclined mixer, the mixing speed is 1500 rpm, and the mixing time is 30 min. The sintering temperature is 1050℃, the sintering time is 5 h, and the heating rate is 2℃ / min. The sintering loading box is a corundum box, and the calcination is carried out in an air atmosphere; after natural cooling, the lithium lanthanum zirconium oxide powder with a light yellow color is obtained. As shown in Figure 2, the diffraction peaks of the lanthanum zirconium oxide solid electrolyte prepared in this embodiment are consistent with the diffraction peaks of cubic lithium lanthanum zirconium oxide, and no impurity phase is generated. Figure 3 As shown in Figure 2, the diffraction peaks of the lanthanum zirconium oxide solid electrolyte prepared in this embodiment are consistent with the diffraction peaks of cubic lithium lanthanum zirconium oxide, and no impurity phase is generated.

[0056] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not conflict, they should be considered within the scope of the present disclosure.

[0057] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A solid electrolyte material, characterized in that, The solid electrolyte material has the chemical formula: Li 7-3y Al y La3Zr 8- 5x Nb x O 12 , where 0.1≤x≤0.4, 0.1≤y<0.

2.

2. The solid electrolyte material according to claim 1, characterized in that, The solid electrolyte material has a cubic phase crystal structure.

3. A method for preparing a solid electrolyte material as described in any one of claims 1-2, characterized in that, Includes the following steps: According to the chemical formula Li 7-3y Al y La3Zr 8-5x Nb x O 12 The raw materials are weighed according to the metric ratio of each element. The raw materials include: lithium source material, lanthanum source material, zirconium source material, aluminum source material and niobium source material; wherein, the lanthanum source is in a small amount of 0.2%-1% and the lithium source is in an excess of 5%-13%. The raw materials are mixed and processed to obtain a mixed product; The mixed product is subjected to solid-state sintering to obtain a sintered product; The sintered product is subjected to a crushing and depolymerization process to obtain the target product; The average particle size of the target product is 100nm-300nm.

4. The preparation method according to claim 3, characterized in that, The mixing process is achieved based on a dry mixing method.

5. The preparation method according to claim 3, characterized in that, The solid-state sintering includes a single sintering process, with a sintering temperature of 1000℃-1200℃ and a sintering time of 5h-20h.

6. The preparation method according to claim 3, characterized in that, The depolymerization and deagglomeration methods include: The sintered product is subjected to primary crushing treatment to obtain a first crushed product, wherein the particle size of the first crushed product is 10μm-50μm; The first crushed product is subjected to a secondary crushing process to obtain a second crushed product, wherein the particle size of the second crushed product is less than 3 μm; The second crushed product is subjected to a three-stage crushing process to obtain a third crushed product, wherein the particle size of the third crushed product is less than 300 nm. The third crushed product is dried to obtain the candidate target product, wherein the drying temperature is 100℃-200℃ and the drying time is 15h-48h. The candidate target product is depolymerized to obtain the target product.

7. The preparation method according to claim 6, characterized in that, The three-stage crushing process includes sand milling, and the sand milling solvent includes alcohol.

8. The preparation method according to claim 6, characterized in that, The depolymerization process includes: breaking the candidate target product into the target product using a disc air jet mill.

9. The preparation method according to claim 3, characterized in that, The lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium nitrate, or lithium acetate. The lanthanum source includes: lanthanum oxide, lanthanum hydroxide, or lanthanum nitrate; The zirconium source includes: zirconium oxide, zirconium hydroxide, zirconium nitrate, or zirconium carbonate; The aluminum source is aluminum oxide; The niobium source is niobium oxide.

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