阅读说明：本技术 一种锂镧锆氧颗粒的制备方法及其产品和应用 (Preparation method of lithium lanthanum zirconium oxide particles, product and application thereof ) 是由 崔大祥 周霖 李天昊 李梦飞 刘鹏飞 张芳 葛美英 于 2020-12-01 设计创作，主要内容包括：本发明提供一种锂镧锆氧(LLZO)的制备方法及其产品和应用,按照锂镧锆氧的原子比溶解硝酸锂、六水合硝酸镧、硝酸氧锆水合物于稀硝酸中,同时加入一定量的络合剂,通过络合反应形成凝胶,再将制得的凝胶进行干燥,干燥完成后将制得的锂镧锆氧凝胶在马弗炉中进行烧结,最终可以得到锂镧锆氧粉末。本发明的优点在于不需要像传统固相烧结法一样将LLZO生粉升温至1200℃以上,可以大幅降低烧结温度至约900℃。具有制备方法简单,易于大批量生产,有很好的应用前景。(The invention provides a preparation method of Lithium Lanthanum Zirconium Oxide (LLZO) and a product and application thereof, which are characterized in that lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate are dissolved in dilute nitric acid according to the atomic ratio of the lithium lanthanum zirconium oxide, a certain amount of complexing agent is added at the same time, gel is formed through complex reaction, the prepared gel is dried, the prepared lithium lanthanum zirconium oxide gel is sintered in a muffle furnace after the drying is finished, and finally, the lithium lanthanum zirconium oxide powder can be obtained. The invention has the advantages that the temperature of the LLZO raw powder does not need to be raised to more than 1200 ℃ like the traditional solid phase sintering method, and the sintering temperature can be greatly reduced to about 900 ℃. Has simple preparation method, easy mass production and good application prospect.)

1. a method for preparing lithium lanthanum zirconium oxygen powder is characterized in that the lithium lanthanum zirconium oxygen raw powder is prepared in a liquid phase environment through a solvent-gel method, and the sintering temperature is reduced to 900 ℃, and the method comprises the following steps:

(1) taking concentrated nitric acid and deionized water, and mixing the following components in percentage by weight: deionized water =1:3, mixing and stirring the mixture to prepare dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate required for preparing lithium lanthanum zirconium oxide, and mixing the raw materials according to the weight ratio of Li: la: zr =7:3:2, adding the diluted nitric acid into the mixed solution, adding excessive lithium nitrate with the concentration of 10wt% and complexing agent with the mole number of 1.2 times of that of the cation, and magnetically stirring the mixed solution until the mixed solution is dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform lithium lanthanum zirconium oxide gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace at 900 ℃, and then cooling along with the furnace to obtain lithium lanthanum zirconium oxygen powder.

2. The method of preparing lithium lanthanum zirconium oxide powder as claimed in claim 1, wherein the lithium nitrate, lanthanum nitrate hexahydrate, zirconyl nitrate hydrate in solution are complexed and gel-formed using citric acid as a complexing agent.

3. The method of preparing lithium lanthanum zirconium oxide powder as claimed in claim 1, wherein the stirring temperature of the solution in the step (3) is maintained at 80 ℃ and the stirring time is 12 hours.

4. The method of preparing lithium lanthanum zirconium oxide powder of claim 1, wherein the lithium lanthanum zirconium oxide gel is dried at 200 ℃ for 2 hours in step (4).

5. The method of preparing lithium lanthanum zirconium oxide powder of claim 1, wherein in step (5), the lithium lanthanum zirconium oxide green powder is sintered in a muffle furnace at 900 ℃ for 8 hours at a temperature rise rate of 5 ℃/min.

6. The method of preparing lithium lanthanum zirconium oxide powder according to any one of claims 1 to 5, characterized by the steps of:

(1) according to the volume ratio of 1:3, mixing and stirring concentrated nitric acid and deionized water to prepare dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate required for preparing lithium lanthanum zirconium oxide, and mixing the raw materials according to the weight ratio of Li: la: zr =7:3:2, adding the mixture into dilute nitric acid, adding excessive lithium nitrate with the concentration of 10wt% and complexing agent citric acid with the mole number of 1.2 times of that of the cation, and magnetically stirring until the mixture is dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform lithium lanthanum zirconium oxide gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace at 900 ℃ for 8 hours at the heating rate of 5 ℃/min, and then cooling along with the furnace to obtain the lithium lanthanum zirconium oxygen powder.

7. The method of preparing lithium lanthanum zirconium oxide powder according to any one of claims 1 to 5, characterized by the steps of:

(1) taking concentrated nitric acid and deionized water according to the volume ratio of 1:4, mixing and stirring to prepare dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate, zirconyl nitrate hydrate and aluminum nitrate nonahydrate required for preparing lithium lanthanum zirconium oxide, adding the raw materials into dilute nitric acid according to the atomic ratio of Li to La to Zr to Al =6.75 to 3 to 2 to 0.25, adding excessive lithium nitrate with the concentration of 10wt% and complexing agent citric acid and glycol with the mole number of 1.2 times of cations, and magnetically stirring until the raw materials are dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace, and then cooling along with the furnace to obtain the lithium lanthanum zirconium oxygen powder.

8. Lithium lanthanum zirconium oxide powder, characterized in that it is obtained by a process according to any one of claims 1 to 7, and is obtained in cubic phase and does not contain tetragonal lithium lanthanum zirconium oxide or other impurities.

9. Use of the lithium lanthanum zirconium oxide powder according to claim 8 for an all solid state lithium ion battery as a solid state electrolyte.

Technical Field

The invention relates to a preparation method of lithium lanthanum zirconium oxygen particles, a product and application thereof, which are applied to the field of manufacturing of all-solid-state lithium ion batteries.

Background

The lithium ion battery has the advantages of high energy density, wide working temperature range, environmental friendliness, large output power, low self-discharge and the like, and is widely applied to the fields of electric automobiles, energy storage equipment, electronic equipment and the like. However, the traditional lithium ion battery contains organic electrolyte which has the characteristics of flammability and easy explosion. If the organic electrolyte leaks under the action of external force, faults such as short circuit and the like are easily caused, and accidents such as combustion, explosion and the like of the battery can be caused in serious cases.

The solid electrolyte is used as a substitute for organic electrolyte, and has the advantages of good chemical stability, long cycle life, high energy density, good mechanical property, stability for lithium metal cathode, simple preparation and assembly and the like. The solid electrolyte comprises an inorganic solid electrolyte, an organic solid electrolyte and a composite electrolyte. Wherein the inorganic solid electrolyte effects the transfer of charge primarily through the movement of lithium ions.

The cubic-phase lithium lanthanum zirconium oxide is a material which is researched more in inorganic solid electrolyte and has the advantages of high lithium ion conductivity, good chemical stability, wide electrochemical window and the like. However, the conventional method for preparing lithium lanthanum zirconium oxide requires high sintering temperature as high as 1200 ℃, and there is much raw material loss during the sieving and ball milling processes. The lithium lanthanum zirconium oxygen raw powder is prepared by a solvent-gel synthesis method, and the sintering temperature of the lithium lanthanum zirconium oxygen raw powder is greatly reduced, thereby being beneficial to actual production.

Disclosure of Invention

In order to reduce the temperature required for sintering the LLZO powder, the present invention aims to provide a method for preparing lithium lanthanum zirconium oxygen particles.

Yet another object of the present invention is to: a lithium lanthanum zirconium oxygen particle product prepared by the above method is provided.

Yet another object of the present invention is to: provides an application of the product.

The purpose of the invention is realized by the following scheme: a method for preparing lithium lanthanum zirconium oxide powder (LLZO) by preparing lithium lanthanum zirconium oxide green powder in a liquid phase environment through a solvent-gel method and reducing a sintering temperature to 900 ℃, comprising the steps of:

(1) taking a proper amount of concentrated nitric acid and deionized water, mixing and stirring according to the ratio of concentrated nitric acid to deionized water =1:3, and preparing dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate required for preparing lithium lanthanum zirconium oxide, adding the raw materials into dilute nitric acid according to the atomic ratio of Li to La to Zr =7 to 3 to 2, adding excessive lithium nitrate (10 wt%) and a proper amount of complexing agent, and magnetically stirring until the excessive lithium nitrate, the lanthanum nitrate hexahydrate and the zirconyl nitrate hydrate are dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace, and then cooling along with the furnace to obtain the lithium lanthanum zirconium oxygen powder.

And adopting citric acid as a complexing agent to complex lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate in the solution to form gel.

In the step (3), the stirring temperature of the solution is kept at 80 ℃ and the stirring time is 12 hours.

In the step (4), the drying temperature of the lithium lanthanum zirconium oxygen gel is 200 ℃, and the drying time is 2 hours.

In the step (5), the sintering temperature of the lithium lanthanum zirconium oxygen raw powder in a muffle furnace is 900 ℃, the sintering time is 8 hours, and the heating rate is 5 ℃/min.

The invention provides lithium lanthanum zirconium oxide powder which is prepared according to any one of the methods and is cubic, and does not contain tetragonal lithium lanthanum zirconium oxide or other impurities.

The invention provides an application of lithium lanthanum zirconium oxygen powder used for an all-solid-state lithium ion battery as a solid electrolyte.

The advantage of this design is that the sintering temperature can be reduced substantially to about 900 ℃ without the need to raise the temperature of the LLZO green powder above 1200 ℃ as in conventional solid phase sintering methods.

The invention discloses a preparation method of lithium lanthanum zirconium oxygen particles, which aims to find a preparation method of lithium lanthanum zirconium oxygen, and a proper amount of complexing agent is added into a liquid phase environment, so that each component in a solution is subjected to a complexing reaction to form a gel-like substance. Compared with the lithium lanthanum zirconium oxygen particles prepared by a solid-phase sintering method after pre-sintering, ball-milling and sieving, the lithium lanthanum zirconium oxygen raw powder prepared by the liquid-phase reaction has smaller particle size and larger specific surface area. Each component can take place more abundant reaction in sintering process, can reduce the required temperature of sintering simultaneously to make more pure cubic phase lithium lanthanum zirconium oxygen granule, reduce the existence of tetragonal phase lithium lanthanum zirconium oxygen and other impurity. The method has simple steps, is easy for mass industrial production, and has good application prospect.

Drawings

FIG. 1 is a photograph of a completed LLZO tablet prepared in example 1;

FIG. 2 is a graph of ion conductivity data of the completed LLZO prepared in example 2 tested in an electrochemical workstation at different temperatures, and it can be seen that the material has higher ion conductivity.

Detailed Description

The present invention is described in detail by the following specific examples, but the scope of the present invention is not limited to these examples.

Example 1

A lithium lanthanum zirconium oxygen powder is prepared by preparing lithium lanthanum zirconium oxygen raw powder in a liquid phase environment by a solvent-gel method, reducing the sintering temperature to 900 ℃, and preparing according to the following steps:

(1) taking a proper amount of concentrated nitric acid and deionized water, wherein the volume ratio of concentrated nitric acid: deionized water =1:3, mixing and stirring the mixture to prepare dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate and zirconyl nitrate hydrate required for preparing lithium lanthanum zirconium oxide, and mixing the raw materials according to the weight ratio of Li: la: zr =7:3:2, adding the mixture into dilute nitric acid, adding excessive lithium nitrate with the concentration of 10wt% and complexing agent citric acid with the mole number of 1.2 times of that of the cation, and magnetically stirring until the mixture is dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform lithium lanthanum zirconium oxide gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven, for example, drying for 2 hours at 200 ℃ to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace for 8 hours at 900 ℃ for example, wherein the heating rate is 5 ℃/min, and then cooling along with the furnace to obtain the lithium lanthanum zirconium oxygen powder. Photographs of the completed LLZO tablets were prepared as shown in FIG. 1. Room temperature ionic conductivity (S/cm) of 1.88X 10^-5See table 1.

Example 2

A method for preparing lithium lanthanum zirconium oxygen powder, compared with the example 1, the raw material of aluminum nitrate nonahydrate Al (NO) is added in the step (2)₃)₃·9H₂O is taken as a dopant, and the steps are as follows:

(1) taking a proper amount of concentrated nitric acid and deionized water, mixing and stirring according to the proportion of concentrated nitric acid to deionized water =1:4, and preparing dilute nitric acid;

(2) taking out raw materials of lithium nitrate, lanthanum nitrate hexahydrate, zirconyl nitrate hydrate and aluminum nitrate nonahydrate required for preparing lithium lanthanum zirconium oxide, adding the raw materials into dilute nitric acid according to the atomic ratio of Li to La to Zr to Al =6.75 to 3 to 2 to 0.25, adding excessive lithium nitrate (10 wt%) and complexing agent citric acid and glycol with the mole number of 1.2 times of cations, and magnetically stirring until the raw materials are dissolved;

(3) stirring the solution obtained in the step (2) overnight to form uniform gel;

(4) drying the lithium lanthanum zirconium oxygen gel obtained in the step (3) in an oven to obtain lithium lanthanum zirconium oxygen raw powder;

(5) and (4) sintering the lithium lanthanum zirconium oxygen raw powder obtained in the step (4) in a muffle furnace, and then cooling along with the furnace to obtain the lithium lanthanum zirconium oxygen powder. Ion conductivity of prepared LLZO at different temperatures tested in electrochemical workstationThe data show that the material has high ionic conductivity, as shown in fig. 2. Room temperature ionic conductivity (S/cm) of 2.12X 10^-5See table 1:

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