WO2020258366A1

WO2020258366A1 - Method for preparing high-li-content lithium alloy

Info

Publication number: WO2020258366A1
Application number: PCT/CN2019/094872
Authority: WO
Inventors: 高炳亮; 刘智伟; 刘成员; 李启明; 牛宏坤; 王聪
Original assignee: 东北大学
Priority date: 2019-06-26
Filing date: 2019-07-05
Publication date: 2020-12-30
Also published as: CN110129834B; CN110129834A

Abstract

A method for preparing a high-Li-content lithium alloy, comprising the following steps: (1) mixing and stirring urea powder and lithium salt powder under the condition of an argon atmosphere to obtain a molten salt electrolyte; (2) providing the molten salt electrolyte in an electrolytic cell, and carrying out constant-potential electrolytic deposition or constant-current electrolytic deposition under the condition of the argon atmosphere; and (3) after the constant-potential electrolytic deposition or constant-current electrolytic deposition is finished, taking out a cathode plate with a lithium alloy deposited on the surface thereof, carrying out surface cleaning, and then drying to prepare a high-Li-content lithium alloy on the surface of the cathode plate. The present invention is featured with short technological process and low production temperature, and the prepared high-Li-content lithium alloy can be directly used for preparing different grades of lithium alloys.

Description

Preparation method of high Li content lithium alloy

Technical field

The invention belongs to the technical field of low-temperature electrolytic metallurgy, and particularly relates to a method for preparing a lithium alloy with high Li content.

Background technique

Lithium is the lightest metal in nature. Adding metallic lithium to aluminum alloy can reduce the density of the alloy and improve the elastic modulus, specific strength, specific stiffness, corrosion resistance and other advantages of the alloy. It is widely used in the aerospace field; Magnesium-lithium alloy is the lightest metal structural material, with high specific strength, specific rigidity and excellent seismic performance, etc., is an ideal structural material.

The traditional method of producing lithium alloys is mainly ingot metallurgy, which is a method of smelting lithium and other high-purity metals under vacuum conditions according to a certain ratio, and directly casting them into ingots; the lithium alloy prepared by this method has a low recovery rate and a process The process is long, the composition is uneven, the cost is high, and the impurity content is limited by the raw material.

Scholars at home and abroad have developed a method for preparing lithium alloys by molten salt electrolysis. Lithium alloys are directly obtained by electrolyzing lithium salts without the need to prepare metallic lithium. However, the electrolysis temperature is relatively high and the high temperature chlorine gas causes serious corrosion to the equipment.

Ionic liquids are a class of green solvents that have developed rapidly in recent years. They have many advantages such as new types, various types, designability, low price, wide electrochemical window, high conductivity, simple synthesis, etc. They are used in catalysis, organic synthesis, dissolution, The application of electrochemistry and other fields has been expanding with the deepening of people's cognition; since the 21st century, a large number of documents have reported the application of electrodeposition to prepare metals and alloys in eutectic solvents. The metals include aluminum, iron, copper, and silver. , Gallium, manganese, molybdenum, etc., alloys include aluminum, platinum, chromium, zinc, manganese, magnesium, etc., but because the deposition potential of lithium is relatively negative, most of the solvents are destroyed before the precipitation of metallic lithium.

Summary of the invention

technical problem

The solution to the problem

Technical solutions

The purpose of the present invention is to provide a method for preparing a lithium alloy with high Li content, which uses urea and lithium salt as a solvent, and uses constant potential or constant current electrodeposition under low temperature conditions to prepare a lithium alloy on the cathode, simplifying the process cut costs.

The method of the present invention is carried out in the following steps:

1. Under argon atmosphere, mix urea powder and lithium salt powder, heat to 50-150℃ under stirring conditions, and continue stirring until a transparent liquid is obtained as a molten salt electrolyte; the moles of urea powder and lithium salt powder The ratio is 2～5;

2. Put the molten salt electrolyte in the electrolytic cell, and perform constant-potential electrodeposition or constant current electrodeposition under the argon atmosphere; when performing constant-potential electrodeposition, the cell body of the electrolytic cell is equipped with a cathode plate and an anode plate And the reference electrode plate, where the cathode plate is made of aluminum, magnesium or copper, the reference electrode plate is made of lithium, and the anode plate is made of lithium, platinum, tungsten, silver or graphite; when performing constant current electrodeposition, the electrolytic cell’s A cathode plate and an anode plate are arranged in the tank. The material of the cathode plate is aluminum, magnesium or copper, and the material of the anode plate is lithium, platinum, tungsten, silver or graphite; the temperature of constant potential electrodeposition or constant current electrodeposition is 50～150 ℃, electrolysis time is 0.5～2h;

3. After the constant potential electrodeposition or constant current electrodeposition is completed, the cathode plate with the lithium alloy deposited on the surface is taken out, the surface is cleaned, and then dried to form a lithium alloy with high Li content on the surface of the cathode plate.

In step 2 above, when performing constant potential electrodeposition, the cathode potential is 0-0.5V.

In step 2 above, when performing constant current electrodeposition, the current density is 1 to 500 mA/cm ² .

In the above step 3, the surface cleaning is to place the cathode plate with the lithium alloy deposited on the surface in ethylene carbonate, and soak for at least 2 hours at a temperature of 50-80°C.

In the above step 3, the drying time is at least 24h under the conditions of vacuum degree ≤50Pa and temperature 80-150℃.

The above-mentioned lithium salt powder is lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bisoxalate, and difluorooxalate borate Lithium or lithium bistrifluoromethanesulfonimide.

The above-mentioned lithium salt powder and urea powder are respectively dried to a moisture mass percentage less than 0.1% before use.

The above-mentioned cathode plate and anode plate are subjected to surface pretreatment before use, including grinding, polishing and ultrasonic cleaning. The ultrasonic cleaning is to place the cathode plate/anode plate in deionized water and apply ultrasonic waves for at least 5 minutes.

In the above method, when performing constant current electrodeposition, the electrolytic cell used is a single-chamber electrolytic cell or a multi-chamber electrolytic cell; the cathode plate of the single-chamber electrolytic cell is located in the middle of the electrolytic cell, and the two anode plates are located on both sides of the cathode plate. There is a channel between the bottom edge of the plate and the bottom of the electrolytic cell; there are multiple cathode plates and multiple anode plates in the multi-chamber electrolyzer, each cathode plate is located between two adjacent anode plates, and the bottom edge of the cathode plate is connected to the There is a channel between the bottom of the electrolysis tank, and the space between two adjacent anode plates is used as an electrolysis chamber, and the number of electrolysis chambers is ≥2.

In the above method, when performing constant potential electrodeposition, the electrolytic cell used is a single-chamber electrolytic cell. The cathode plate of the single-chamber electrolytic cell is located in the middle of the electrolytic cell, and the anode plate and the reference electrode plate are located on both sides of the cathode plate. There is a passage between the bottom edge and the bottom of the electrolytic cell.

In the above step 4, the high-Li-content lithium alloy on the surface of the cathode plate contains 13-20% Li by mass percentage.

The beneficial effects of the invention

Beneficial effect

The beneficial effects of the present invention are:

(1) The process flow is short, and the production temperature is lower than that of the traditional ingot metallurgy method and high-temperature molten salt electrolysis method, which greatly reduces energy consumption;

(2) Among the selected raw materials, urea is cheap, and adjusting the type and amount of lithium salt can effectively reduce the cost; the high lithium content lithium alloy made can be directly used to prepare different grades of lithium alloy;

(3) Conduct constant potential electrodeposition on different metal substrates to obtain different lithium alloys;

(4) Changing the process parameters can obtain alloys with different morphologies, sizes and thicknesses.

Brief description of the drawings

Description of the drawings

Fig. 1 is a schematic flow chart of a method for preparing a lithium alloy with high Li content in an embodiment of the present invention;

2 is an X-ray diffraction diagram of the deposit on the surface of the cathode plate in Example 1 of the present invention;

3 is a schematic diagram of the structure of a single-chamber electrolytic cell in embodiment 1 of the present invention;

4 is a schematic diagram of the structure of a single-chamber electrolytic cell in Example 9 of the present invention;

5 is a schematic diagram of the structure of a multi-chamber electrolytic cell in Embodiment 10 of the present invention;

In the figure, 1. Electrode guide rod, 2. Single-chamber electrolytic cell first anode plate, 3. Single-chamber electrolytic cell cathode plate, 4. Single-chamber electrolytic cell second anode plate, 5. Single-chamber electrolytic cell body, 6 , Molten salt electrolyte, 7. Multi-chamber electrolytic cell anode plate, 8. Multi-chamber electrolytic cell cathode plate, 9. Multi-chamber electrolytic cell body, 10. Reference electrode.

Invention embodiment

Embodiments of the invention

The urea used in the example of the present invention is a commercially available analytical reagent.

Lithium chloride, lithium fluoride, lithium bromide, lithium iodide, lithium nitrate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bisoxalate, and difluorooxalate borate used in the examples of the present invention Lithium and lithium bistrifluoromethanesulfonimide are commercially available analytical reagents.

Before using the lithium salt powder and urea powder in the example of the present invention, after drying and grinding, the part with a particle size of -200 mesh is sieved and stored in an argon atmosphere glove box.

In the example of the present invention, the lithium salt powder and the urea powder are respectively dried to a moisture mass percentage of <0.1% before use.

The cathode plate used in the example of the present invention is aluminum plate, copper plate or magnesium plate, and the purity is ≥99.99%.

The preparation method of the electrolyte liquid in the example of the present invention is: adding the urea powder to the lithium salt powder and stirring at room temperature, heating to 50-150°C, stirring for at least 4h, and stirring rate of 300-500r/min.

In the example of the present invention, after the surface pretreatment of the cathode plate and the anode plate, they are sealed and stored in a glove box under an argon atmosphere.

In the example of the present invention, the cathode plate and the anode plate are subjected to surface pretreatment before use, including grinding, polishing and ultrasonic cleaning. The ultrasonic cleaning is to place the cathode plate/anode plate in deionized water and apply ultrasonic waves for at least 5 minutes.

The reference electrode plate in the example of the present invention is a lithium plate with a purity of ≥99.9%, and the surface oxide layer is scraped off before use to expose the silver-white metallic luster.

In the example of the present invention, the cathode potential is 0-0.5V (vs. Li/Li ⁺ ) when performing constant potential electrodeposition; when performing constant current electrodeposition, the current density is 1 to 500 mA/cm ² .

In the example of the present invention, the configuration of the electrolyte and the constant potential electrolysis process are all performed in a glove box in an argon atmosphere.

The equipment used for analyzing the composition of the master alloy in the embodiment of the present invention is a 4300DV inductively coupled plasma emission spectrometer (ICP), and the phase composition analysis of the product uses an X-ray diffractometer (XRD) of MPDDY2094 produced by PANalytical Corporation of the Netherlands.

In the embodiment of the present invention, there are n cathode plates and n+1 anode plates in the multi-chamber electrolyzer, and n>1.

In the embodiment of the present invention, the material deposited on the cathode plate is scraped off to obtain lithium alloy powder.

The process in the embodiment of the present invention is shown in FIG. 1.

Example 1

Under argon atmosphere, mix urea powder and lithium salt powder, heat to 100°C under stirring, and continue stirring until a transparent liquid is obtained as a molten salt electrolyte; wherein the molar ratio of urea powder to lithium salt powder is 3; The lithium salt powder is lithium chloride;

Place the molten salt electrolyte in the electrolytic cell, and perform constant-potential electrodeposition under the argon atmosphere. The electrolytic cell is a single-chamber electrolytic cell. The structure is shown in Figure 3. The single-chamber electrolytic cell body 5 has a single chamber. The cathode plate 3 of the electrolytic cell, the first anode plate 2 of the single-chamber electrolytic cell and the reference electrode plate 10, the cathode plate 3 of the single-chamber electrolytic cell is located in the middle of the single-chamber electrolytic cell body 5, the first anode plate 2 of the electrolytic cell and the reference electrode The plates 10 are respectively located on both sides of the cathode plate 3 of the single-chamber electrolytic cell. There is a channel between the bottom side of the single-chamber electrolytic cell cathode plate 3 and the bottom of the single-chamber electrolytic cell body 5; the material of the single-chamber electrolytic cell cathode plate 3 is aluminum, reference The material of the electrode plate 10 is lithium, and the material of the first anode plate 2 of the electrolytic cell is lithium; each electrode is connected to the workstation through the electrode lead 1; the temperature of constant potential electrodeposition or constant current electrodeposition is 100℃, the electrolysis time is 1h; the cathode potential -0.5V;

After constant potential electrodeposition or constant current electrodeposition, the cathode plate with lithium alloy deposited on the surface is taken out. The X-ray diffraction pattern of the deposit on the surface of the cathode plate is shown in Figure 2. The cathode plate is placed in ethylene carbonate, and the temperature is Soaked at 80℃ for 2h, and then dried for 24h at vacuum ≤50Pa and temperature at 100℃. A high-Li-content lithium alloy is made on the surface of the cathode plate, which contains 15.98% Li by mass percentage, and the rest is aluminum.

Example 2

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 80°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 5; the lithium salt powder is lithium fluoride;

(2) The material of the cathode plate is magnesium, and the material of the anode plate is platinum; the electrodeposition temperature is 80℃, the electrolysis time is 2h; the cathode potential is -0.5V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked at a temperature of 80℃ for 3h, and then dried for 24h at a vacuum degree of ≤50Pa and a temperature of 80℃, and a high-Li content lithium alloy is made on the surface of the cathode plate , Contains 16.54% Li in mass percentage, and the rest is magnesium.

Example 3

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 120°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 2; the lithium salt powder is lithium bromide;

(2) The cathode plate is made of copper and the anode plate is made of tungsten; the electrodeposition temperature is 120°C, the electrolysis time is 0.5h; the cathode potential is -0.3V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 2.5h at a temperature of 80℃, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 90℃, and high Li content lithium is formed on the surface of the cathode plate. The alloy contains 17.23% Li by mass percentage, and the rest is copper.

Example 4

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 150°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 4; the lithium salt powder is lithium iodide;

(2) The material of the cathode plate is aluminum, and the material of the anode plate is silver; the electrodeposition temperature is 150℃, the electrolysis time is 2h; the cathode potential is -0.3V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked at a temperature of 80°C for 3h, and then dried for 24h at a vacuum degree of ≤50Pa and a temperature of 110°C, and a high Li content lithium alloy is made on the surface of the cathode plate , Containing 17.53% Li by mass percentage, and the rest is aluminum.

Example 5

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 50°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 2.5; the lithium salt powder is lithium nitrate;

(2) The material of the cathode plate is magnesium, and the material of the anode plate is graphite; the electrodeposition temperature is 50℃, the electrolysis time is 2h; the cathode potential is -0.3V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 3 hours at a temperature of 80 ℃, and then dried for 24 hours at a vacuum degree of ≤ 50 Pa and a temperature of 120 ℃, and a high Li content lithium alloy is made on the surface of the cathode plate , It contains 15.79% Li by mass percentage, and the rest is magnesium.

Example 6

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 110°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 2; the lithium salt powder is lithium tetrafluoroborate;

(2) The material of the cathode plate is magnesium and the material of the anode plate is platinum; the electrodeposition temperature is 110℃, the electrolysis time is 2h; the cathode potential is -0.5V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 3.5h at a temperature of 80℃, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 80℃, to form high Li content lithium on the surface of the cathode plate The alloy contains 15.45% Li by mass percentage, and the rest is magnesium.

Example 7

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 130°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 3.5; the lithium salt powder is lithium perchlorate;

(2) The material of the cathode plate is magnesium, and the material of the anode plate is tungsten; the electrodeposition temperature is 130℃, the electrolysis time is 2h; the cathode potential is -0.5V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked at a temperature of 80°C for 3h, and then dried for 24h at a vacuum degree of ≤50Pa and a temperature of 130°C, and a high-Li content lithium alloy is made on the surface of the cathode plate , Contains 19.52% Li by mass percentage, and the rest is magnesium.

Example 8

The method is the same as in Example 1, the difference is:

(1) The urea powder and the lithium salt powder are mixed and heated to 140°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 2.5; the lithium salt powder is lithium hexafluoroarsenate;

(2) The cathode plate is made of copper, and the anode plate is made of silver; the electrodeposition temperature is 140°C, the electrolysis time is 1.5h; the cathode potential is -0.3V;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 2.5h at a temperature of 80℃, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 80℃, and high Li content lithium is formed on the surface of the cathode plate. The alloy contains 18.81% Li by mass percentage, and the rest is copper.

Example 9

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 150°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 4.5; the lithium salt powder is lithium hexafluorophosphate;

(2) Constant current electrodeposition; the electrolytic cell used is a single-chamber electrolytic cell, the structure is shown in Figure 4, the cathode plate 3 of the multi-chamber electrolytic cell is located in the middle of the single-chamber electrolytic cell body 5, and the first anode of the single-chamber electrolytic cell The plate 2 and the second anode plate 4 of the single-chamber electrolytic cell are respectively located on both sides of the cathode plate 3 of the multi-chamber electrolytic cell. There is a channel between the bottom side of the cathode plate 3 of the multi-chamber electrolytic cell and the bottom of the single-chamber electrolytic cell body 5; the cathode plate and The two anode plates are respectively connected to the workstation through the electrode guide rod 1; the material of the cathode plate is aluminum, and the material of the anode plate is lithium; the temperature of constant current electrodeposition is 150℃, the electrolysis time is 2h; the current density is 1mA/cm ² ;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 3.5h at a temperature of 80℃, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 150℃ to produce high Li content lithium on the surface of the cathode plate The alloy contains 13.44% Li by mass percentage, and the rest is aluminum.

Example 10

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 95°C under agitation, the molar ratio of the urea powder to the lithium salt powder is 3.5; the lithium salt powder is lithium bis-oxalate borate;

(2) Constant current electrodeposition; the electrolytic cell used is a multi-chamber electrolytic cell, the structure is shown in Figure 5. The multi-chamber electrolytic cell body 9 is provided with 6 multi-chamber electrolytic

cell cathode plates

8 and 7 multi-chamber Electrolyzer anode plate 7, each multi-chamber electrolytic cell cathode plate 8 is located between two adjacent multi-chamber electrolytic cell anode plates 7, the bottom edge of the multi-chamber electrolytic cell cathode plate 8 and the bottom of the multi-chamber electrolytic cell body 9 There is a channel between, and the space between the anode plates 7 of two adjacent multi-chamber electrolyzers is used as an electrolysis chamber, the number of electrolysis chambers=6; each cathode plate and each anode plate are respectively connected to the power supply through the electrode guide rod 1; The material of the cathode plate is magnesium, and the material of the anode plate is graphite; the temperature of constant current electrodeposition is 95℃, the electrolysis time is 2h; the current density is 20mA/cm ² ;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked at a temperature of 80℃ for 3h, and then dried for 24h at a vacuum degree of ≤50Pa and a temperature of 85℃, and a high-Li content lithium alloy is made on the surface of the cathode plate , It contains 14.17% Li by mass percentage, and the rest is magnesium.

Example 11

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 105°C under stirring conditions, the molar ratio of the urea powder to the lithium salt powder is 3.5; the lithium salt powder is lithium difluorooxalate;

(2) Constant current electrodeposition; the electrolytic cell used is a single-chamber electrolytic cell, the cathode plate is located in the middle of the electrolytic cell, two anode plates are located on both sides of the cathode plate, and there is a channel between the bottom edge of the cathode plate and the bottom of the electrolytic cell; The material of the plate is copper, and the material of the anode plate is graphite; the temperature of constant current electrodeposition is 105℃, the electrolysis time is 2h; the current density is 200mA/cm ² ;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked for 4h at a temperature of 70℃, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 145℃, and a high Li content lithium alloy is made on the surface of the cathode plate , Containing 16.33% Li according to mass percentage, the rest is copper.

Example 12

The method is the same as in Example 1, the difference is:

(1) After mixing the urea powder and the lithium salt powder, heat to 125°C under stirring conditions, and the molar ratio of the urea powder to the lithium salt powder is 4; the lithium salt powder is lithium bistrifluoromethanesulfonimide;

(2) Constant current electrodeposition; the electrolytic cell used is a multi-chamber electrolytic cell, the structure is shown in Figure 4. The multi-chamber electrolytic cell is equipped with n cathode plates and n+1 anode plates, and each cathode plate is Located between two adjacent anode plates, there is a channel between the bottom edge of the cathode plate and the bottom of the electrolytic cell. The space between the two adjacent anode plates is used as an electrolysis chamber, the number of electrolysis chambers = n; the material of the cathode plate Copper, anode plate material is graphite; constant current electrodeposition temperature is 125℃, electrolysis time is 2h; current density is 500mA/cm2;

(3) After the cathode plate is taken out, it is placed in ethylene carbonate, soaked at a temperature of 60℃ for 6h, and then dried for 24h under the conditions of a vacuum degree of ≤50Pa and a temperature of 135℃, and a high Li content lithium alloy is made on the surface of the cathode plate , It contains 18.93% Li by mass percentage, and the rest is copper.

Claims

A method for preparing a lithium alloy with high Li content is characterized in that it is carried out in the following steps:

(1) Under argon atmosphere, mix urea powder and lithium salt powder, heat to 50-150℃ under stirring, and continue stirring until a transparent liquid is obtained as a molten salt electrolyte; where the urea powder and lithium salt powder The molar ratio is 2～5;

(2) Put the molten salt electrolyte in the electrolytic cell, and perform constant-potential electrodeposition or constant current electrodeposition under the argon atmosphere; when performing constant-potential electrodeposition, the electrolytic cell is equipped with a cathode plate and an anode Plates and reference electrode plates, where the cathode plate is made of aluminum, magnesium or copper, the reference electrode plate is made of lithium, and the anode plate is made of lithium, platinum, tungsten, silver or graphite; when performing constant current electrodeposition, the electrolytic cell The tank body is equipped with a cathode plate and an anode plate, wherein the material of the cathode plate is aluminum, magnesium or copper, and the material of the anode plate is lithium, platinum, tungsten, silver or graphite; the temperature of constant potential electrodeposition or constant current electrodeposition is 50～ 150℃, electrolysis time 0.5～2h;

(3) After the constant potential electrodeposition or the constant current electrodeposition is completed, the cathode plate with the lithium alloy deposited on the surface is taken out, the surface is cleaned, and then dried to form a lithium alloy with high Li content on the surface of the cathode plate.
The method for preparing a lithium alloy with high Li content according to claim 1, wherein in step (2), during constant potential electrodeposition, the cathode potential is 0-0.5V.
The method for preparing a lithium alloy with high Li content according to claim 1, wherein in step (2), during constant current electrodeposition, the current density is 1 to 500 mA/cm 2 .
The method for preparing a lithium alloy with high Li content according to claim 1, wherein in step (3), the surface cleaning is to place the cathode plate with the lithium alloy deposited on the surface in ethylene carbonate at a temperature of 50 ~ Soak for at least 2h at 80℃.
The method for preparing a lithium alloy with high Li content according to claim 1, characterized in that in step (3), the drying is performed under the conditions of vacuum ≤50 Pa and temperature 80-150°C for at least 24 hours.
The method for preparing a lithium alloy with high Li content according to claim 1, wherein the lithium salt powder is lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium nitrate, lithium tetrafluoroborate, Lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium bisoxalate borate, lithium difluorooxalate borate, or lithium bistrifluoromethanesulfonimide.
The method for preparing a lithium alloy with high Li content according to claim 1, wherein the cathode plate and anode plate are subjected to surface pretreatment before use, including grinding, polishing and ultrasonic cleaning, wherein ultrasonic cleaning is The plate/anode plate is placed in deionized water and ultrasonic waves are applied for at least 5 minutes.
The method for preparing a lithium alloy with high Li content according to claim 1, wherein in step (2), when performing constant current electrodeposition, the electrolytic cell used is a single-chamber electrolytic cell or a multi-chamber electrolytic cell; The cathode plate of the single-chamber electrolytic cell is located in the middle of the electrolytic cell, and the two anode plates are located on both sides of the cathode plate. There is a channel between the bottom edge of the cathode plate and the bottom of the electrolytic cell; a multi-chamber electrolytic cell is equipped with multiple cathode plates and multiple anode Each cathode plate is located between two adjacent anode plates. There is a channel between the bottom edge of the cathode plate and the bottom of the electrolytic cell. The space between the two adjacent anode plates serves as an electrolysis chamber. Quantity≥2.
The method for preparing a lithium alloy with high Li content according to claim 1, characterized in that in step (2), when performing constant-potential electrodeposition, the electrolytic cell used is a single-chamber electrolytic cell. The cathode plate is located in the middle of the electrolytic cell, the anode plate and the reference electrode plate are respectively located on both sides of the cathode plate, and there is a channel between the bottom edge of the cathode plate and the bottom of the electrolytic cell.
The method for preparing a high-Li-content lithium alloy according to claim 1, wherein in step (4), the high-Li-content lithium alloy on the surface of the cathode plate contains 13-20% Li by mass percentage.