阅读说明：本技术 一种石榴石型无机固体电解质材料的低温烧结方法 (Low-temperature sintering method of garnet-type inorganic solid electrolyte material ) 是由 马骋 王新超 于 2020-06-22 设计创作，主要内容包括：本发明提供了一种石榴石型无机固体电解质的低温烧结方法,即冷烧结技术,具体为：将LiCl和InCl<Sub>3</Sub>溶解在特定溶剂中,得到混合溶液；将混合溶液与石榴石型无机固体电解质陶瓷粉末混合,得到混合物；随后对混合物进行低温热压成型与退火,即完成冷烧结过程。上述低温烧结中所需温度不高于400℃,却可以实现传统高温固相反应法1200℃下烧结12小时所能达到的致密度和锂离子电导率。与现有技术相比,本发明提供的方法具有烧结温度低,工艺周期短,能耗少等特点,且由该技术制得的电解质材料致密度高、锂离子电导率优异。(The invention provides a low-temperature sintering method of garnet type inorganic solid electrolyte, namely a cold sintering technology, which comprises the following steps: LiCl and InCl 3 Dissolving in a specific solvent to obtain a mixed solution; mixing the mixed solution with garnet type inorganic solid electrolyte ceramic powder to obtain a mixture; and then carrying out low-temperature hot-press molding and annealing on the mixture to finish the cold sintering process. The required temperature in the low-temperature sintering is not higher than 400 ℃, but the compactness and the lithium ion conductivity which can be achieved by sintering for 12 hours at 1200 ℃ by using the traditional high-temperature solid-phase reaction method can be realized. Compared with the prior artCompared with the prior art, the method provided by the invention has the characteristics of low sintering temperature, short process period, low energy consumption and the like, and the electrolyte material prepared by the technology has high density and excellent lithium ion conductivity.)

1. A low-temperature sintering method of garnet-type inorganic solid electrolyte material comprises the following steps:

A) LiCl and InCl₃Dissolving in a solvent to obtain a mixed solution;

B) mixing garnet-type inorganic solid electrolyte ceramic powder with the mixed solution to obtain a mixture;

C) carrying out hot pressing on the mixture and then maintaining the pressure to obtain an initial material;

D) carrying out heat treatment on the initial material to obtain a garnet type inorganic solid electrolyte material; the temperature of the heat treatment is 200-400 ℃.

2. The low-temperature sintering method according to claim 1, wherein in the step A), the dissolving is performed under an inert atmosphere, and the solvent is one or more selected from ethanol, water, acetone, and ethylene glycol.

3. Low temperature sintering process according to claim 1 or 2, characterised in that the LiCl and the InCl are present₃The molar ratio of (1-5): 1.

4. the low-temperature sintering method according to claim 1 or 2, wherein in step C), the hot pressing further comprises: and placing the mixture into a forming die, and then placing the forming die into a hydraulic press with a heating module.

5. The low-temperature sintering method according to claim 4, wherein the hot pressing pressure is 10 to 300MPa, the temperature is 100 to 200 ℃, the temperature rise rate of the hot pressing is 3 to 10 ℃/min, and the pressure maintaining time is 1 to 3 hours.

6. The low-temperature sintering method according to claim 1 or 2, wherein the mixing in step B) and the hot-pressing and pressure holding in step C) are performed under an inert atmosphere.

7. The low-temperature sintering method according to claim 1 or 2, wherein the step D) further comprises, before the heat treatment: the starting material was sealed in a vacuum glass tube.

8. The low-temperature sintering method according to claim 7, wherein the heat treatment time is 3 to 5 hours.

9. The low-temperature sintering method according to any one of claims 1 to 8, wherein the garnet-type inorganic solid electrolyte is cubic phase Li₇La₃Zr₂O₁₂A base material.

10. A lithium ion battery comprises a positive electrode, a negative electrode and a solid electrolyte, and is characterized in that the solid electrolyte is a garnet-type inorganic solid electrolyte material prepared by the low-temperature sintering method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of lithium ion batteries, in particular to a low-temperature sintering method of a garnet type inorganic solid electrolyte material.

Background

The lithium ion battery has the advantages of high specific capacity, good cycle performance and the like, so that the lithium ion battery is widely applied to products such as portable electronic equipment and electric automobiles. Currently, the electrolyte of most commercial lithium ion batteries is a liquid organic solution. The liquid organic electrolyte has high lithium ion conductivity (up to 10)^-2S cm^-1) Thereby ensuring the rapid transmission of lithium ions and ensuring that the battery has good performance. However, such electrolytes have potential safety hazards such as leakage, fire, even explosion, and the like, and therefore, the above problems can be effectively solved by replacing the conventional liquid organic electrolyte with a solid electrolyte with good thermal stability.

Among solid electrolytes, inorganic oxide solid electrolytes are receiving attention because of their good ionic conductivity, wide electrochemical window, and excellent mechanical strength. Among them, garnet-type inorganic solid electrolyte-cubic phase Li synthesized by Murugan, German scientist₇La₃Zr₂O₁₂The (LLZO) based material (angelw. chem. int. ed.,2007,46, 7778-.

However, in the preparation of the above solid electrolyte using a conventional high-temperature solid-phase reaction method, the sintering temperature is generally 1200 ℃ or higher; the problem of unavoidable serious lithium volatilization caused by excessively high sintering temperature is solved, so that the process repeatability is poor, and the prepared electrolyte has excellent and stable lithium ion conductivity. To solve this problem, researchers have made various attempts to lower the sintering temperature; for example, with Li₃BO₃As a sintering aid, the sintering temperature can be reduced to 900 ℃ (electrochem. commun.,2013,33, 51-54); the sintering temperature can be reduced to 900-1000 ℃ by using the leading-edge sintering method such as hot-pressing sintering (J.Mater.Sci.,2012,47,4428-4431) and spark plasma sintering (J.Power Sources,2014,249, 197-206). Nevertheless, the sintering temperature is still higher than 900 ℃, and the problem of lithium volatilization cannot be effectively solved.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a low-temperature sintering method of a garnet-type inorganic solid electrolyte material, which can realize the preparation of the garnet-type inorganic solid electrolyte material at low temperature and has high density.

The application provides a low-temperature sintering method of a garnet-type inorganic solid electrolyte material, which comprises the following steps:

A) LiCl and InCl₃Dissolving in a solvent to obtain a mixed solution;

B) mixing garnet-type inorganic solid electrolyte ceramic powder with the mixed solution to obtain a mixture;

C) carrying out hot pressing on the mixture and then maintaining the pressure to obtain an initial material;

D) carrying out heat treatment on the initial material to obtain a garnet type inorganic solid electrolyte material; the temperature of the heat treatment is 200-400 ℃.

Preferably, in step a), the dissolving is performed under an inert atmosphere, and the solvent is one or more selected from ethanol, water, acetone, and ethylene glycol.

Preferably, the LiCl and the InCl₃The molar ratio of (1-5): 1.

preferably, in step C), before the hot pressing, the method further comprises: and placing the mixture into a forming die, and then placing the forming die into a hydraulic press with a heating module.

Preferably, the pressure of the hot pressing is 10-300 MPa, the temperature is 100-200 ℃, the heating rate of the hot pressing is 3-10 ℃/min, and the pressure maintaining time is 1-3 h.

Preferably, the mixing in step B) and the hot pressing and holding in step C) are performed under an inert atmosphere.

Preferably, step D) further comprises, before the heat treatment: the starting material was sealed in a vacuum glass tube.

Preferably, the time of the heat treatment is 3-5 h.

Preferably, the garnet-type inorganic solid electrolyte is cubic phase Li₇La₃Zr₂O₁₂A base material.

The application also provides a lithium ion battery, which comprises a positive electrode, a negative electrode and a solid electrolyte, and is characterized in that the solid electrolyte is a garnet-type inorganic solid electrolyte material prepared by the low-temperature sintering method in the scheme.

This application providesA low-temp sintering method for garnet-type inorganic solid electrolyte material includes such steps as mixing LiCl with InCl₃Dissolving in a solvent to obtain a mixed solution, mixing garnet-type inorganic solid electrolyte ceramic powder with the mixed solution to obtain a mixture, and then hot-pressing, maintaining pressure and performing heat treatment on the mixture at a low temperature to obtain a garnet-type inorganic solid electrolyte material; the present application utilizes LiCl and InCl₃The mixture of the garnet-type inorganic solid electrolyte ceramic powder and the garnet-type inorganic solid electrolyte ceramic powder can reduce the hot pressing and heat treatment temperature, ensure that the heat treatment temperature is 400 ℃ at most, effectively avoid the problem of lithium volatilization and ensure that the prepared garnet-type inorganic solid electrolyte material has high density.

Drawings

FIG. 1 is a comparison of the process flow of the cold sintering process provided by the present invention and the process route of the traditional high temperature solid phase reaction method;

FIG. 2 is a schematic diagram of a hydraulic press with a heating module used in embodiments 1 to 3 of the present invention;

FIG. 3 is a scanning electron micrograph of a cubic phase LLZO-based solid electrolyte prepared by a cold sintering process obtained in example 1 of the present invention;

FIG. 4 is an electrochemical impedance spectrum of a cubic phase LLZO-based solid electrolyte prepared using a cold sintering process obtained in example 1 of the present invention;

FIG. 5 is an electrochemical impedance spectrum of a cubic phase LLZO-based solid electrolyte prepared by a cold sintering process obtained in example 2 of the present invention;

FIG. 6 is an electrochemical impedance spectrum of a cubic phase LLZO-based solid electrolyte prepared using a cold sintering process obtained in example 3 of the present invention.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

In view of the problem that the sintering temperature of the current garnet-type solid electrolyte material is high, the application provides a pomegranateThe low-temperature sintering method of the stone-type inorganic solid electrolyte material, which can also be called as the cold sintering technology of the garnet-type solid electrolyte material, is shown in a specific flow chart in figure 1 and is realized by introducing LiCl and InCl₃As a mixed solution, the hot pressing temperature and the heat treatment temperature are greatly reduced, lithium volatilization is avoided, and the density of the garnet-type inorganic solid electrolyte material is ensured. Specifically, the embodiment of the invention discloses a low-temperature sintering method of a garnet-type inorganic solid electrolyte material, which comprises the following steps:

A) LiCl and InCl₃Dissolving in a solvent to obtain a mixed solution;

B) mixing garnet-type inorganic solid electrolyte ceramic powder with the mixed solution to obtain a mixture;

C) carrying out hot pressing on the mixture and then maintaining the pressure to obtain an initial material;

D) carrying out heat treatment on the initial material to obtain a garnet type inorganic solid electrolyte material; the temperature of the heat treatment is 200-400 ℃.

In the process of preparing a garnet-type inorganic solid electrolyte material, the present application first combines LiCl and InCl₃Dissolving in solvent to obtain mixed solution. In the above process, the LiCl and InCl₃The molar ratio of (A) to (B) is 1-5: 1. The solvent is selected from the group consisting of LiCl and InCl which are effective in dissolving the above LiCl and InCl₃And is volatile removable by the lower temperature, in view of this, the solvent is specifically selected from one or more of water, ethanol, acetone and ethylene glycol. The above process is carried out under an inert atmosphere.

Mixing garnet type inorganic solid electrolyte ceramic powder with the mixed solution to obtain a mixture; in the present application, the garnet-type inorganic solid electrolyte ceramic powder is cubic phase Li well known to those skilled in the art₇La₃Zr₂O₁₂(LLZO) based material, in particular embodiments, the cubic phase Li₇La₃Zr₂O₁₂The (LLZO) based material is specifically Li_6.4La₃Zr_1.4Ta_0.6O₁₂Other constants can be selectedSee Li₇La₃Zr₂O₁₂(LLZO) based material, to which the present application is not particularly limited. The above step of obtaining a mixture is carried out under an inert atmosphere.

According to the invention, the mixture is subjected to hot pressing and pressure maintaining to obtain an initial material; before hot pressing, the mixture needs to be placed in certain equipment for hot pressing, namely the hot pressing also comprises the following steps: and placing the mixture into a forming die, and then placing the forming die into a hydraulic press of a heating module. The pressure applied in the hot pressing is 10-300 MPa, the temperature applied is 100-200 ℃, and the heating rate is 3-10 ℃/min; in a specific embodiment, the applied pressure is 100-220 MPa, the applied temperature is 130-180 ℃, and the heating rate is 5-8 ℃/min. And the pressure maintaining time is 1-3 h. The hot pressing and pressure maintaining are carried out in an inert atmosphere.

After the initial material is obtained, the obtained initial material is sealed in a vacuum glass tube and then placed in a heat treatment furnace for annealing treatment, namely cold sintering is completed, and thus the garnet-type inorganic solid electrolyte material prepared by the cold sintering technology is obtained. The temperature of the heat treatment is 200-400 ℃, and the time is 3-5 h.

The sources of all the raw materials are not particularly limited in the present application, and the raw materials are commercially available products.

The application provides a low-temperature sintering method for garnet-type inorganic solid electrolyte materials, the temperature required by the cold sintering process is 400 ℃ at most, the problem of lithium volatilization can be effectively avoided, the production energy consumption is reduced, and the large-scale production of the garnet-type inorganic solid electrolyte materials in industry is facilitated. The experimental results show that: the garnet type inorganic solid electrolyte material prepared by the cold sintering technology has high density and excellent lithium ion conductivity (up to 10)^-4S cm^-1)。

In order to further understand the present invention, the low-temperature sintering method of the garnet-type inorganic solid electrolyte material provided by the present invention is described in detail below with reference to the following examples, and the scope of the present invention is not limited by the following examples.

The reagents used in the following examples are all commercially available.