CN115642297A - Halide solid electrolyte and method for preparing same - Google Patents

Abstract

The invention discloses a halide solid electrolyte and a preparation method thereof, wherein the chemical general formula of the halide solid electrolyte is Li _3‑x In _1‑x Zr _x Cl ₆ Wherein, X =0.01-0.5; the preparation method comprises the following steps: step 1: halide electrolyte halogen salts LiCl and InCl ₃ And ZrCl ₄ Dispersing in alcohol solution to obtain mixed solution; step 2: stirring the mixed solution to completely dissolve halide electrolyte halogen salt and completely volatilize the alcohol solution to obtain a halide electrolyte precursor; and step 3: and carrying out heat treatment on the halide electrolyte precursor to obtain the halide solid electrolyte. The method realizes the rapid preparation of the halide solid electrolyte by combining the solution method and the low-temperature heat treatment method, the preparation process is simple, and the prepared halide solid electrolyte has higher lithium ion conductivity and can meet the performance requirements and large-scale production requirements of different all-solid-state lithium batteries.

Description

Halide solid electrolyte and preparation method thereof

technical field

The invention relates to a battery material and a preparation method thereof, in particular to a halide solid electrolyte and a preparation method thereof.

Background technique

As a battery material with high safety, solid-state electrolyte has gradually replaced the traditional flammable liquid electrolyte in energy storage systems such as all-solid-state lithium batteries (ASSLB). Among various types of inorganic solid electrolytes, battery materials that can be applied to ASSLB include oxide solid electrolytes, sulfide solid electrolytes, and halide solid electrolytes, among which the ionic conductivity of oxide solid electrolytes and sulfide solid electrolytes exceeds 1mS /cm, which is considered to be the most promising candidate material for ASSLB.

For oxide solid electrolytes, the entire synthesis process requires a high sintering temperature (usually >700°C) to promote the contact between the electrode material and the solid electrolyte, and the preparation process is cumbersome, the sintering time is long, and the manufacturing cost is increased. May cause interface side reactions.

As for the sulfide solid-state electrolyte, it has strict requirements on the environment. Due to its instability with water, it is easy to cause harmful hydrogen sulfide gas to be released during the synthesis process, and the conductivity of lithium ions is greatly reduced.

For halide solid-state electrolytes, the structure of halide solid-state electrolytes is based on the ion stacking of ionic bonds. Through the structure of these ionic bond frameworks, lithium ions (Li+) have different phenomena and diffusion mechanisms when migrating in halide solid-state electrolytes. Halide solid-state electrolytes have the characteristics of wide electrochemical window and stable counter electrode. Therefore, halide solid-state electrolytes are suitable for all-solid-state lithium batteries and have the potential for excellent electrochemical performance. The synthesis method of the halide solid electrolyte in the prior art generally adopts the high-energy mechanical ball milling method, which has problems such as long synthesis period, cumbersome preparation process, high sintering temperature, long sintering time, and high cost.

Chinese invention patent application CN201910843405.4 discloses an electrode, an electrolyte thin layer and its preparation method, and specifically discloses that: the solid electrolyte material is Li _a MX _b , and M is Al, Ga, In, Sc, Y, La X is one or more of F, Cl, Br, 0≤a≤10, 1≤b≤13. In the preparation method, the positive electrode material is coated with a halide electrolyte to improve the lithium ion conductivity of the positive electrode material, and the preparation method is complicated.

Chinese invention patent application CN202011629509.4 discloses a solid electrolyte material and its preparation method and solid-state lithium battery, and specifically discloses: the chemical formula of the halide solid electrolyte material is Li _a MeX _b O _c , wherein: Me is selected from Elements Mg, Ca, Sr, Ba, Zn, Al, Ga, In, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc , Bi, Zr, Hf, Ti, Nb or Ta; X is at least one of F, Cl or Br; 2.0≤a≤4.0; 4.5≤b≤7.5; 0<c≤0.1. The electrolyte material is easy to produce Me-OX heterophase compound when the oxidant is introduced, resulting in a decrease in the ionic conductivity of the halide solid electrolyte material. At the same time, the introduction of O element will lead to an increase in the heat treatment temperature, such as a heat treatment temperature of 300-650 ° C, resulting in Increased costs.

Contents of the invention

One of the objects of the present invention is to provide a halide solid-state electrolyte, which has high lithium ion conductivity and is suitable for all-solid-state lithium batteries.

The second object of the present invention is to provide a method for preparing a halide solid electrolyte, which simplifies the preparation process, shortens the preparation time, reduces the difficulty of preparation, and is easy for large-scale production.

The present invention is achieved like this:

A halide solid electrolyte, the general chemical formula of the halide solid electrolyte is Li _3-x In _1-x Zr _x Cl ₆ , where X=0.01-0.5.

A method for preparing a halide solid electrolyte, comprising the following steps:

Step 1: Disperse the halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ in the alcohol solution to obtain a mixed solution;

Step 2: Stir the mixed solution to completely dissolve the halogen salt of the halide electrolyte, and completely volatilize the alcohol solution to obtain a precursor of the halide electrolyte;

Step 3: heat-treating the halide electrolyte precursor to obtain a halide solid electrolyte Li _3-x In _1-x Zr _x Cl ₆ , where X=0.01-0.5.

In the step 1, the alcohol solution is one or a mixture of methanol solution, ethanol solution, isopropanol solution and n-butanol solution.

In the step 1, the ratio range of the halide electrolyte halide salt LiCl, InCl ₃ and ZrCl ₄ is (2.5-2.99):(0.5-0.99):(0.01-0.5).

In the step 2, the stirring temperature is 50-80°C.

The stirring rate is 100-1500 rpm.

In the step 3, the heat treatment is vacuum atmosphere heat treatment.

The temperature range of the heat treatment is 100-300°C.

The heating rate of the heat treatment is 1-20° C./minute.

The heat preservation time of the heat treatment is 1-12 hours.

Compared with the prior art, the present invention has the following beneficial effects:

1. The halide solid electrolyte of the present invention introduces zirconium element to replace a part of indium element, has high lithium ion conductivity, is suitable for all-solid lithium batteries, and can achieve halides with different lithium ion conductivity by controlling the content of zirconium element A solid-state electrolyte to meet the performance requirements of an all-solid-state lithium battery and reduce the raw material cost of a halide solid-state electrolyte.

2. The preparation method of the present invention combines the solution method and low-temperature heat treatment method, without the need for mechanical ball milling synthesis, sintering and other processes, which simplifies the preparation process, avoids tedious preparation procedures, and does not need to provide higher sintering temperature and longer sintering time , the preparation cost and preparation time are greatly reduced, and the prepared halide solid electrolyte has high lithium ion conductivity, which can meet the requirements of large-scale production.

The present invention realizes the fast preparation of the halide solid electrolyte through the combination of the solution method and the low-temperature heat treatment method, the preparation process is simple, and the prepared halide solid electrolyte has high lithium ion conductivity, which can meet different all-solid lithium batteries performance requirements and mass production requirements.

Detailed ways

A halide solid electrolyte, the general chemical formula of the halide solid electrolyte is Li _3-x In _1-x Zr _x Cl ₆ , where X=0.01-0.5.

A method for preparing a halide solid electrolyte, comprising the following steps:

Step 1: Disperse the halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ in the alcohol solution to obtain a mixed solution.

The alcohol solution is one or a combination of methanol solution, ethanol solution, isopropanol solution and n-butanol solution.

The ratio range of the halide electrolyte halogen salt LiCl, InCl ₃ and ZrCl ₄ is (2.5-2.99):(0.5-0.99):(0.01-0.5), and the addition amount of Zr is limited to avoid excessive addition of Zr Large resulting halide phase impurity and LiCl residue.

Step 2: Stir the mixed solution to completely dissolve the halogen salt of the halide electrolyte and completely volatilize the alcohol solution to obtain a precursor of the halide electrolyte.

The stirring temperature is 50-80° C. to ensure that the alcohol solution can volatilize.

The stirring speed is 100-1500 rpm, which is beneficial to the volatilization of the alcohol solution.

Step 3: heat-treating the halide electrolyte precursor to obtain a halide solid electrolyte Li _3-x In _1-x Zr _x Cl ₆ , where X=0.01-0.5.

The heat treatment can be carried out in vacuum atmosphere heat treatment and the like.

The temperature range of the heat treatment is 100-300°C, to ensure that a pure-phase halide solid electrolyte can be obtained after the heat treatment, avoiding the oxidative decomposition of the halide solid electrolyte caused by too high temperature, and the halide solid electrolyte lithium ion caused by too low temperature. Poor electrical conductivity.

The heating rate of the heat treatment is 1-20° C./minute, and the temperature is kept at the required temperature after being raised to the desired temperature.

The holding time of the heat treatment is 1-12 hours to ensure that a pure-phase halide solid electrolyte is obtained.

Example 1:

The halide electrolyte halogen salts LiCl, InCl ₃ and ZrCl ₄ will be taken according to the ratio of 2.9:0.9:0.1 and dispersed in the ethanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 300 rpm at a temperature of 60° C. for 24 hours to completely volatilize the ethanol solution to obtain a halide electrolyte precursor. The halide electrolyte precursor was placed in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment was 280°C, and the heating rate was 2°C/min. After the temperature was raised to 280°C, it was kept for 4 hours to obtain a halide solid electrolyte Li _2.9 In _0.9 Zr _0.1 Cl ₆ , that is, X=0.1.

Example 2:

The halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ will be taken in a ratio of 2.8:0.8:0.2 and dispersed in methanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 600 rpm at a temperature of 60°C for 24 hours to completely volatilize the methanol solution to obtain a halide electrolyte precursor. The halide electrolyte precursor was placed in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment was 100°C, and the heating rate was 3°C/min. After the temperature was raised to 100°C, it was kept for 3 hours to obtain a halide solid electrolyte Li _2.8 In _0.8 Zr _0.2 Cl ₆ , that is, X=0.2.

Example 3:

The halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ will be taken according to the ratio of 2.7:0.7:0.3 and dispersed in the isopropanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 500 rpm at a temperature of 60°C for 24 hours to completely volatilize the isopropanol solution to obtain a halide electrolyte precursor. The halide electrolyte precursor was placed in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment was 300°C, and the heating rate was 5°C/min. After the temperature was raised to 300°C, it was kept for 4 hours to obtain a halide solid electrolyte Li _2.7 In _0.7 Zr _0.3 Cl ₆ , that is, X=0.3.

Example 4:

The halide electrolyte halogen salts LiCl, InCl ₃ and ZrCl ₄ will be taken according to the ratio of 2.6:0.6:0.4 and dispersed in the ethanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 400 rpm at a temperature of 60°C for 24 hours to completely volatilize the ethanol solution to obtain a halide electrolyte precursor. The halide electrolyte precursor was placed in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment was 280°C, and the heating rate was 10°C/min. After the temperature was raised to 280°C, it was kept for 3 hours to obtain the halide solid electrolyte Li _2.6 In _0.6 Zr _0.4 Cl ₆ , that is, X=0.4.

Example 5:

The halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ will be taken in a ratio of 2.5:0.5:0.5 and dispersed in n-butanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 500 rpm at a temperature of 60° C. for 24 hours to completely volatilize the n-butanol solution to obtain a halide electrolyte precursor. The halide electrolyte precursor was placed in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment was 300 °C, and the heating rate was 15 °C/ _min . In _0.5 Zr _0.5 Cl ₆ , that is, X=0.5.

Embodiment 6:

The halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ will be taken according to the ratio of 2.99:0.99:0.01 and dispersed in the ethanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 500 rpm at a temperature of 60°C for 24 hours to completely volatilize the ethanol solution to obtain a halide electrolyte precursor. Put the halide electrolyte precursor in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment is 270°C, and the heating rate is 20°C/min. After the temperature is raised to 270°C, it is kept for 2 hours to obtain the halide solid electrolyte Li _2.99 In _0.99 Zr _0.01 Cl ₆ , that is, X=0.01.

Embodiment 7:

The halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ will be taken according to the ratio of 2.95:0.95:0.05 and dispersed in the ethanol solution to obtain a mixed solution. Stir the mixed solution at a rate of 500 rpm at a temperature of 60°C for 24 hours to completely volatilize the ethanol solution to obtain a halide electrolyte precursor. Place the halide electrolyte precursor in a tube furnace for heat treatment in a vacuum atmosphere. The temperature of the vacuum atmosphere heat treatment is 300°C, and the heating rate is 5°C/min. After the temperature is raised to 300°C, it is kept for 2 hours to obtain the halide solid electrolyte Li _2.95 In _0.95 Zr _0.05 Cl ₆ , that is, X=0.05.

Table 1 shows the lithium ion conductivity of the halide solid electrolyte Li _3-x In _1-x Zr _x Cl ₆ prepared in Examples 1-7 at 30°C.

Table 1 The halide solid-state electrolyte prepared by Example 1-7 and its lithium ion conductivity and the prior art solid electrolyte and its lithium ion conductivity

Example Electrolyte chemical formula Lithium ion conductivity (mS/cm) Example 1 Li_2.9In_0.9Zr_0.1Cl₆ 2.315 Example 2 Li_2.8In_0.8Zr_0.2Cl₆ 2.456 Example 3 Li_2.7In_0.7Zr_0.3Cl₆ 2.302 Example 4 Li_2.6In_0.6Zr_0.4Cl₆ 2.014 Example 5 Li_2.5In_0.5Zr_0.5Cl₆ 1.867 Example 6 Li_2.99In_0.99Zr_0.01Cl₆ 1.625 Example 7 Li_2.95In_0.9Zr_0.05Cl₆ 1.932 current technology Li₃InCl₆ 1.547

It can be seen from Table 1 that the lithium ion conductivity of the halide solid electrolyte Li _3-x In _1-x Zr _x Cl ₆ at 30°C increases first and then decreases with the increase of zirconium (Zr) doping amount, among which Li _2.8 In _0.8 Zr _0.2 Cl ₆ exhibited the highest Li-ion conductivity of 2.456 mS/cm. At the same time, compared with the solid electrolyte Li ₃ InCl ₆ in the prior art, the lithium ion conductivity of the Li _3-x In _1-x Zr _x Cl ₆ prepared by the present invention is significantly improved.

Claims (10)

1. A halide solid electrolyte, characterized in that: the general chemical formula of the halide solid electrolyte is Li _{3- x} In _1-x Zr _x Cl ₆ , where X=0.01-0.5. 2. A preparation method of the halide solid electrolyte as claimed in claim 1, characterized in that: comprising the following steps: Step 1: Disperse the halide electrolyte halide salts LiCl, InCl ₃ and ZrCl ₄ in the alcohol solution to obtain a mixed solution; Step 2: Stir the mixed solution to completely dissolve the halogen salt of the halide electrolyte, and completely volatilize the alcohol solution to obtain a precursor of the halide electrolyte; Step 3: heat-treating the halide electrolyte precursor to obtain a halide solid electrolyte Li _3-x In _1-x Zr _x Cl ₆ , where X=0.01-0.5. 3. The preparation method according to claim 2, characterized in that: in the step 1, the alcohol solution is one or more mixtures of methanol solution, ethanol solution, isopropanol solution and n-butanol solution. 4. the preparation method according to claim 2 is characterized in that: in described step 1, the ratio scope of halide electrolyte halide salt LiCl, InCl ₃ and ZrCl ₄ is (2.5-2.99):(0.5-0.99) :(0.01-0.5). 5. The preparation method according to claim 2, characterized in that: in said step 2, the stirring temperature is 50-80°C. 6. The preparation method according to claim 2 or 5, characterized in that: the stirring speed is 100-1500 rpm. 7. The preparation method according to claim 2, characterized in that: in the step 3, the heat treatment is vacuum atmosphere heat treatment. 8. The preparation method according to claim 2 or 7, characterized in that: the temperature range of the heat treatment is 100-300°C. 9. The preparation method according to claim 2 or 7, characterized in that: the heating rate of the heat treatment is 1-20°C/min. 10. The preparation method according to claim 2 or 7, characterized in that: the holding time of the heat treatment is 1-12 hours.