WO2024061312A1

WO2024061312A1 - A method and device for preparing high-purity lithium chloride based on lithium-ion solid electrolyte

Info

Publication number: WO2024061312A1
Application number: PCT/CN2023/120374
Authority: WO
Inventors: Kai Liu; Xinzhou LI; Di Zhang; Yukang WU; Lemou WU
Original assignee: Beijing Yeeneng New Energy Technology Co Ltd
Current assignee: Beijing Yeeneng New Energy Technology Co Ltd
Priority date: 2022-09-22
Filing date: 2023-09-21
Publication date: 2024-03-28
Anticipated expiration: 2025-03-22
Also published as: RS20250281A1; RS20250281A9; CL2025000859A1; CL2025000862A1; CN117737751A

Abstract

A method for preparing high-purity lithium chloride from low-purity lithium chloride salt based on lithium-ion solid electrolyte. The method involves using dry low-purity lithium chloride salt made from salt lake brine, seawater, or solid minerals as the raw material, and directly producing high-purity lithium chloride through electrolytic reaction using lithium-ion solid electrolyte.

Description

A METHOD AND DEVICE FOR PREPARING HIGH-PURITY LITHIUM CHLORIDE BASED ON LITHIUM-ION SOLID ELECTROLYTE

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese Patent Application No. 202211160954. X, filed on September 23, 2022. The above application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of lithium chloride preparation technology, and in particular, to a method and device for preparing high-purity lithium chloride based on lithium-ion solid electrolyte.

BACKGROUND

Lithium chloride, as an important basic material of lithium salt, has a wide range of applications. In the metallurgical industry, lithium chloride is used for the electrolytic production of metallic lithium, which is currently the main method for industrial production of metallic lithium. In the fields of biology and medicine, lithium chloride can be used to treat diabetes, synthesize pharmaceutical intermediates, and separate and purify small amounts of RNA, among others. In the field of new materials, it is used to produce chitosan. In most applications, high purity lithium chloride is required, especially in the production of metallic lithium, where a purity of 99.3 wt%or higher is required. Currently, the industrial-grade lithium chloride in global market is almost saturated, but the supply of high-purity lithium chloride falls short of demand, and the price of high-purity lithium chloride is much higher than that of industrial-grade products.

In nature, lithium exists in two forms: solid minerals and liquid minerals. Solid minerals mainly include lithium mica, spodumene, and lepidolite, while liquid minerals are divided into salt lake brine, seawater, and underground brine. Among the two forms of lithium deposits, salt lake lithium deposits account for 69%of global lithium resources and are the main form of lithium deposits.

The traditional method for producing lithium chloride is to convert Li+ in ore or brine into LiOH or Li₂CO₃, and then react it with Cl₂ or HCl to produce LiCl. This method consumes a large amount of raw materials and has high production costs.

CN201510438178.9 discloses a method for extracting lithium chloride from high-lithium salt lake brine, comprising the following steps:

S1. add high-lithium salt lake brine into the reaction vessel, then add carbonate solution to remove calcium and magnesium ions. Heat up, keep warm, and filter out calcium carbonate and magnesium carbonate;

S2. add barium salt to the product obtained in S1 to remove sulfate ions in brine, heat up, keep warm, and filter to remove barium sulfate;

S3. add inorganic acid to the product of S2 to remove boron, adjust the pH value, and filter to remove boric acid;

S4. add strong alkali to the product from S3 to adjust the pH value of the solution to 2-3;

S5. add a chelating agent to the S4 product to remove trace amounts of calcium and magnesium ions, then evaporate and concentrate to obtain acidic lithium chloride crystals;

S6. dissolve the product from S5 in water to obtain a lithium chloride solution, adjust the pH value by adding alkali, heat up and keep warm;

S7. spray dry the product from S6 to obtain solid particles of lithium chloride.

CN201610959801. X discloses a process for preparing high-purity anhydrous lithium chloride by centrifugal extraction of salt lake brine, comprising the following steps:

S1. Material Pretreatment: pre-treat the depleted brine of potassium and sodium by removing the boron acid, solid impurities, and suspended solids in the brine;

S2. Material Preparation: in the pre-treated brine after potassium and sodium removal, add industrial hydrochloric acid and mix thoroughly for acidification treatment;

S3. Multi-stage Countercurrent Centrifugal Extraction: the acid-adjusted brine is pumped into the heavy phase inlet of a multi-stage series of centrifugal extractors in the extraction section. At the same time, an organic solution containing an amide-complexing extractant is pumped into the light phase inlet of the multi-stage series of centrifugal extractors as the extracting organic phase. The ratio of the two phases is controlled at oil phase: water phase = 2: 1. The organic solution containing the amide-complexing extractant is a mixture of N523 and TBP, and is thoroughly mixed with sulfonated kerosene as a diluent and ferric chloride as a synergistic extractant. The organic phase containing the amide-complexing extractant and the brine undergo multi-stage countercurrent centrifugal extraction in the extraction section of the multi-stage series of centrifugal extractors to obtain a loaded organic phase and a raffinate water phase;

S4. Multi-stage Countercurrent Washing: the loaded organic phase obtained in step S3 is introduced into the light phase inlet of a multi-stage cascade centrifugal extractor in the washing section, which is controlled by a closed-loop flow control system with a variable frequency drive. Meanwhile, the washing agent is introduced into the heavy phase inlet of a multi-stage cascade annular gap centrifugal extractor through a closed-loop flow control system with a variable frequency drive. The oil-to-water ratio in the washing section is controlled to be 40: 1. The loaded organic phase is subjected to multi-stage countercurrent washing in the washing section of the centrifugal extractor to remove impurity ions including calcium, magnesium, potassium, and sodium in the loaded organic phase, obtaining a high-purity lithium-containing loaded organic phase;

S5. Multi-stage Countercurrent Extraction: the lithium-loaded organic phase obtained in step S3 enters the light phase inlet of the multi-stage cascade centrifugal extractor in the extraction section through the variable frequency closed-loop flow control system. At the same time, the extractant enters the heavy phase inlet of the multi-stage cascade annular gap centrifugal extractor through the variable frequency closed-loop flow control system. The ratio of the extraction section is controlled to be oil phase: water phase=40: 1. Both phases enter the extraction machine through the variable frequency closed-loop flow control system to control the flow rate. After the multi-stage countercurrent extraction, the lithium in the loaded organic phase is transferred into the aqueous solution through the extraction agent, which is a concentrated 6mol/L hydrochloric acid. A high-purity lithium chloride-rich aqueous solution is obtained. 20%of the flow rate of the lithium-rich aqueous solution obtained after extraction is used as a washing agent and added to the washing process of the loaded organic phase. The remaining solution enters the iron removal section, while the organic phase after extraction enters the saponification section for saponification regeneration;

S6. Saponification: the saponification agent used is a 4mol/L sodium hydroxide solution. The organic phase output from the reverse extraction section enters the saponification section to remove the hydrochloric acid contained in it. The ratio of organic phase to alkaline solution is 40: 1. After saponification, the regenerated organic phase is returned to the centrifugal extraction section;

S7. Iron Removal: the enriched lithium water solution obtained after reverse extraction is divided into two streams, with 20%of the flow returning to the washing section as washing agent. The remaining 80%of the flow enters the iron removal section, where N523 organic solvent is added as the iron removal extractant, and sulphonated kerosene is added as a diluent. The ratio of oil phase to water phase in this section is 2: 1. The iron ion impurities in the enriched lithium water solution obtained after reverse extraction are removed, and high-purity lithium chloride water solution is obtained. The iron removal extractant is regenerated by adding pure water through reverse extraction and is reused repeatedly;

S8. Oil Removal: after iron removal, the high-purity lithium chloride aqueous solution enters the oil removal section, where a gravity and ultrasound air flotation oil removal system is used to reduce the carried oil phase to below 10ppm, further improving the purity of the lithium chloride solution.

S9. finally, through the processes of evaporation concentration, crystallization, separation, drying, and packaging, high-purity anhydrous lithium chloride products are obtained.

CN201710309394.2 discloses a production process for high-purity lithium chloride, and the equipment in this production process includes a series of connected filter presses, an acid-adjustment tank for acid adjustment, an extraction system, a washing system, a back-extraction system, an iron removal system, and an oil removal system. The output end of the back-extraction solution in the back-extraction system is also connected to the washing system, and the organic phase output end of the back-extraction system is connected to the saponification system, which is connected to the extraction system. The extraction system, washing system, back-extraction system, and saponification system form a circulating loop.

The salt lake workers in various countries have conducted extensive research on the development of new methods for preparing lithium chloride. This disclosure summarizes the main methods and materials used for extracting lithium chloride, as well as their advantages and disadvantages, in Table 1.

Table 1: Known methods for the preparation of lithium chloride

According to Table 1, it can be seen that the existing methods for preparing lithium chloride mainly have the following deficiencies: complex process; high cost; low purity of extracted lithium chloride; and not environmentally friendly.

To solve the difficulty of preparing high-purity lithium chloride and a series of problems in the production process, the present disclosure proposes a device/method for preparing high-purity lithium chloride using an electrochemical method through a lithium-ion ceramic electrolyte.

SUMMARY

According to an aspect of the present disclosure, a device for preparing high-purity lithium chloride is provided, including a cathode chamber, an anode chamber, and lithium-ion ceramic electrolyte. The cathode chamber is configured for storing molten cathode salt. The anode chamber is configured for storing low-purity lithium chloride salt with a purity of 1 wt%-98 wt%. The lithium-ion ceramic electrolyte is placed between the cathode chamber and the anode chamber, the lithium-ion ceramic electrolyte serves as both an electrolyte that only allows lithium ions to pass through and a diaphragm to prevent material mixing between the cathode chamber and the anode chamber.

In some embodiments, the lithium-ion ceramic electrolyte is selected from the garnet-type oxide Li_7-xLa₃Zr_2-xTa_xO₁₂, where x is selected from 0-1.0; a thickness of the lithium-ion ceramic electrolyte is from 0.01 cm to 2.0 cm; and a relative density is from 85%-99.9%.

In some embodiments, the cathode molten salt comprises lithium chloride/aluminum chloride or lithium chloride/zinc chloride.

In some embodiments, the molten cathode salt is a mixed salt of lithium chloride and aluminum chloride or a mix of lithium chloride and zinc chloride, wherein a molar ratio of LiCl to (AlCl₃+LiCl) in the mixed salt is in the range of 0 to 0.99, or 0.43 to 0.51.

In some embodiments, the molar ratio of LiCl to (AlCl₃+LiCl) in the mixed salt is in the range of 0.43 to 0.51.

According to another aspect of the present disclosure, a method for preparing high-purity lithium chloride through lithium-ion ceramic electrolyte is provided, including:

(1) adding low-purity lithium chloride salt as anode salt in an anode chamber of a reaction vessel, where a purity of the low-purity lithium chloride salt is 1 wt%-98 wt%;

(2) adding a cathode salt to a cathode chamber of the reaction vessel, wherein the cathode salt includes LiCl/AlCl₃ or LiCl/ZnCl₂;

(3) providing a lithium-ion ceramic electrolyte between the cathode chamber and the anode chamber, wherein the lithium-ion ceramic electrolyte serves as both an electrolyte that only allows lithium ions to pass through and a diaphragm to prevent material mixing between the cathode chamber and the anode chamber;

(4) heating the reaction vessel at a temperature higher than a melting point of the low-purity lithium chloride salt and the cathode salt;

(5) applying an electric current to the reaction vessel, with a current density of 1-500 mA/cm² and a voltage of 0-4V; and

(6) separating LiCl from AlCl₃ or separating LiCl from ZnCl₂ of the cathode molten salt at a separation device and obtaining high-purity LiCl with a purity of more than 99 wt%.

In some embodiments, the current density is 50-150 mA/cm².

In some embodiments, the voltage is 0-1.5V.

In some embodiments, the temperature is 100℃-1000℃.

In some embodiments, the temperature is 200℃-400℃.

In some embodiments, the separation device uses vacuum distillation to remove AlCl₃. The conditions for the vacuum distillation include: at a temperature range of 100℃-1000℃ and at a pressure of less than or equal to 0.1 MPa.

In some embodiments, the conditions for the vacuum distillation include: at a temperature range of 200℃-400℃ and at a pressure between 0.05 MPa and-0.05 MPa.

In some embodiments, the separation device uses an electrochemical electrolysis method to remove AlCl₃.

In some embodiments, the low-purity lithium chloride salt is sourced from one of salt lakes, salt mines, seawater, or lithium mines.

DESCRIPTION OF THE DRAWINGS

The present disclosure's above-mentioned and/or additional aspects and advantages will become apparent and easily understood from the description of the embodiments in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic diagram of the electrolytic device of the present disclosure.

FIG. 2 is the separation device of aluminum chloride and lithium chloride of the present disclosure.

FIG. 3 is a graph showing the relationship between current density and voltage in Embodiment 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the disclosure. However, one skilled in the art will understand that the disclosure may be practiced without these details. Moreover, while various embodiments of the disclosure are disclosed herein, many adaptations and modifications may be made within the scope of the disclosure in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the disclosure in order to achieve the same result in substantially the same way.

Unless the context requires otherwise, throughout the present specification and claims, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to. ” Recitation of numeric ranges of values throughout the specification is intended to serve as a shorthand notation of referring individually to each separate value falling within the range inclusive of the values defining the range, and each separate value is incorporated in the specification as it were individually recited herein. Additionally, the singular forms “a, ” “an” and “the” include plural referents unless the context clearly dictates otherwise.

Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may be in some instances. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

The present disclosure provides a device and method for preparing high-purity lithium chloride through an electrochemical method using a lithium-ion ceramic electrolyte, which aims to address the issues in the preparation of lithium chloride using existing technologies.

A method for preparing high-purity lithium chloride from low-purity lithium chloride salt based on lithium-ion solid electrolyte is provided in the present disclosure.

In some embodiments, high-purity lithium chloride may be directly prepared through the electrolytic reaction using dry low-purity lithium chloride salt made from salt lake brine, seawater, solid minerals, etc. as raw material.

The present disclosure provides a device for preparing high-purity lithium chloride by using a lithium-ion ceramic electrolyte. The device includes a cathode chamber and an anode chamber, where the cathode chamber is used to store the molten cathode salt, and the anode chamber is used to store low-purity lithium chloride salt. The purity of the low-concentration lithium chloride salt can be selected from 1 wt%-98 wt%, such as 8 wt%, 28 wt%, 48 wt%, 68 wt%, or 88 wt%, or between any two of the above numbers. The lithium-ion ceramic electrolyte is located between the cathode chamber and the anode chamber, the lithium-ion ceramic electrolyte serves as an electrolyte that allows only lithium ions to pass through, and as a separator to prevent material mixing between the two electrodes.

In some embodiments, the lithium-ion ceramic electrolyte selected for the preparation of high-purity lithium chloride is Li_7-xLa₃Zr_2-xTa_xO₁₂ solid electrolyte with a garnet structure. The value of x can be selected from 0 to 1.0, for example, X can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. The electrolyte has a cross-sectional thickness from 0.01 cm to 2.0 cm, which can be 0.1 cm, 0.2 cm, 0.5 cm, 1.0 cm, 1.2 cm, 1.5 cm, or 1.8 cm. The thicker the cross-sectional thickness of the solid electrolyte, the higher the internal resistance and the polarization voltage of the device, resulting in lower energy efficiency. The thickness is thus kept equal to or less than 2 cm. However, increasing the thickness of the solid electrolyte can help extend its service life and improve the product purity. The thickness is thus kept equal to or greater than 0.01 cm. The relative density of the solid electrolyte can be between 85%-99.9%, such as 88%, 90%, 93%, 95%, or 99%, or between any two of the above numbers. The higher the relative density of the solid electrolyte is, the more helpful it is for extending its service life and improving the product purity. In some embodiments, the lithium-ion ceramic electrolyte can also be selected from solid electrolytes, such as Li_1+xAl_xTi_2-x (PO₄) ₃, where the value of x can be chosen between 0.3-0.4, and specific values of x can be 0.33, 0.35, 0.37, etc. The solid electrolyte has a cross-sectional thickness from 0.01 cm to 2.0 cm, which can be 0.1 cm, 0.2 cm, 0.5 cm, 1.0 cm, 1.2 cm, 1.5 cm, 1.8 cm. The relative density is from 85%-99.9%, with specific values of, for example, 88%, 90%, 93%, 95%, 99%or between any two of the above numbers.

In some embodiments, the molten cathode salt can be lithium chloride/aluminum chloride or lithium chloride/zinc chloride, etc.

In some embodiments, the molten cathode salt is a mixture of lithium chloride and aluminum chloride, with a mass ratio of LiCl: (AlCl₃+LiCl) in the range of 0-99%, or 19.3-24.8%. With this ratio, the molten cathode salt can be fully melted at relatively low temperature, which can help to reduce the ionic diffusion resistance, lower the polarization voltage, and improve the energy efficiency during the operation process.

The present disclosure also provides a method for preparing high-purity lithium chloride using a lithium-ion ceramic electrolyte, which includes the following steps:

(1) adding low-purity lithium chloride salt, with a purity of 1 wt%-98 wt%, as the molten anode salt in the anode chamber of the reaction vessel;

(2) adding molten cathode salt, which may be lithium chloride/aluminum chloride or lithium chloride/zinc chloride, etc., to the cathode chamber of the reaction vessel;

(3) providing a lithium-ion ceramic electrolyte between the cathode chamber and the anode chamber. The lithium-ion ceramic electrolyte serves as both an electrolyte that only allows lithium ions to pass through and a diaphragm to prevent material mixing between the cathode chamber and the anode chamber;

(4) heating the reaction vessel above the melting point of the molten salt to melt the molten salt;

(5) applying an electric current to the reaction vessel, with a current density of 1-500 mA/cm², or between 50-150 mA/cm², or 60 mA/cm², 80 mA/cm², 100 mA/cm², 120 mA/cm², 140 mA/cm² or between any two of the above values. The voltage can range from 0-4 V, or 0-1.5 V, or 0.5 V, 0.8 V, 1.0 V, or 1.2 V, or between any two of the above values;

(6) separating LiCl from AlCl₃ or separating LiCl from ZnCl₂ of the molten cathodic salt at a separation unit, and obtaining high-purity LiCl with a purity of over 99 wt%.

In some embodiments, the temperature range to produce the molten salt can be 100℃- 1000℃, or 200℃-400℃.

In some embodiments, the molten cathode salt is a mixed refined salt of lithium chloride and aluminum chloride, or lithium chloride and zinc chloride. The mass ratio of the mixed refined salt LiCl: (AlCl₃ (or ZnCl₂) +LiCl) is 0-99%, or 19.3-24.8%. With this ratio, the molten cathode salt can be more fully melted, which is conducive to reducing ion diffusion resistance, lowering polarization voltage, and improving energy efficiency during operation.

In some embodiments, the reaction voltage is in the range of 0-4V, or between 0.5-1.5V. The voltage may be 0.5V, 0.8V, 1.0V, and 1.2V, or between any two of the above values.

The aluminum chloride and lithium chloride separation unit further adopts vacuum distillation to remove AlCl₃. The conditions for vacuum distillation are: temperature range of 100℃-1000℃, or 200℃-400℃, and pressure less than or equal to 0.1 Mpa, or between 0.05 Mpa to -0.05 Mpa.

In some embodiments, the separation device for aluminum chloride and lithium chloride uses an electrochemical method to remove AlCl₃.

In some embodiments, AlCl₃ is collected after condensation and is reused again.

In some embodiments, the low-purity lithium chloride salt for the molten anode salt can be sourced from salt lakes, salt mines, seawater, lithium mines, etc., with lithium chloride purity ranging from 1%-98%.

In some embodiments, the molten anode salt also contains one or several chloride additives such as AlCl₃, MgCl₂, FeCl₂, and ZnCl₂, which are used to lower the melting point of the molten salt.

In some embodiments, the molten anode salt contains NaCl, KCl, MgCl₂, and AlCl₃.

The present disclosure provides a method/device for preparing high-purity lithium chloride through lithium-ion ceramic electrolyte, and the principle of the technical solution is as follows:

Inserting metals that participate in the reaction (such as Al, Zn, etc. ) into the molten anode salt as a sacrificial anode electrode, the anode metal needs to maintain contact with the molten anode salt during the purification process; using metal chlorides that participate in the reaction (such as AlCl₃, ZnCl₂, etc. ) and low-purity lithium chloride salt to form a low-melting-point mixed salt as the anode, which is heated above its melting point during the purification process and stored in the anode chamber; the lithium-ion ceramic electrolyte can be selected as the garnet-type oxide Li_7-xLa₃Zr_2-xTa_xO₁₂ (LLZTO) solid electrolyte or Li_1.3Al_0.3Ti_1.7 (PO₄) ₃ (LATP) , etc., where x can be selected between 0-1.0; with a cross-sectional thickness from 0.01 cm to 2.0cm. Generally, under the same conditions, the thicker the solid electrolyte cross-section, the higher the device internal resistance, the higher the device polarization voltage, and the lower the device energy efficiency. However, an increase in solid electrolyte thickness helps extend the lifespan of the solid electrolyte, improve product purity. The relative density is from 85%-99.9%. Generally, under the same conditions, the higher the relative density of the solid electrolyte, the more it helps extend the lifespan of the solid electrolyte and improve product purity. As a solid electrolyte isolating the anode and cathode, this type of solid electrolyte can selectively allow Li+ ions to pass through, and other ions are difficult to pass through. Using high-purity lithium chloride and high-purity metal chlorides (such as AlCl₃, ZnCl₂, etc. ) that participate in the reaction to form a low-melting-point mixed salt as the molten cathode salt and store it in the cathode chamber, which is then heated above its melting point during the purification process.

Using metals that participate in the electrochemical reaction (such as Al, Zn, etc. ) or inert electrodes (such as carbon) inserted into the molten cathode salt as the cathode, the cathode metal needs to maintain contact with the molten cathode salt during the extraction process. The entire device constitutes an electrolytic cell. During the operation of the device, the anode undergoes sacrificial electrode oxidation to form chloride ions, Li+ passes through the solid electrolyte to generate lithium chloride at the cathode, and the aluminum or zinc metal ions in the molten cathode salt are reduced to metal at the electrode.

In some embodiments, the reaction process is as follows:

The anode reaction is: Me -ne-= Meⁿ⁺

The cathode reaction is: Meⁿ⁺ + ne-= Me

"Me" here refers to metals such as Al, Zn, Fe, Mg, etc., and the anode and cathode Me can be the same or different. "n" refers to the number of gained or lost electrons.

In some embodiments, the temperature range of the reaction process can be defined as 100℃-1000℃, or between 200℃-400℃.

In some embodiments, when using, the anode and cathode are energized with a voltage of 0-4V, or 0.5-1.5V or 0.5V, 0.8V, 1.0V, 1.2V or between any two of the above values.

The present disclosure has at least three significant advantages. Firstly, high-purity lithium chloride can be obtained at a lower cost. The cost estimate for obtaining lithium chloride described in this article is only 20%of the cost of traditional methods. Secondly, the voltage can be controlled below 1.5V during purification, enhancing the diversity of equipment material selection. Thirdly, compared to traditional methods of preparing LiCl through LiOH and Cl₂ or hydrochloric acid, this technology does not use agents such as Cl₂ or hydrochloric acid, making it environmentally friendly. In summary, compared to traditional methods, this technology is environmentally friendly, has lower purification voltage, and lower production costs.

This statement indicates that the following detailed explanations are only examples intended to provide further information on the present disclosure, and the terms used are only to describe specific embodiments rather than to limit the exemplary embodiments based on the present disclosure.

This paragraph explains that the detailed embodiments disclosed in the following are only examples to provide further explanation of the invention and are not intended to limit the embodiments of the invention. The disclosed embodiments are only partial examples of the possible embodiments that may be claimed in the claims, and other embodiments, modifications, and equivalents not shown in the disclosed embodiments are also within the scope of the claims.

Implementation Example 1: An apparatus for preparing high-purity lithium chloride using a lithium-ion ceramic electrolyte. The basic equipment diagram for preparing lithium chloride is shown in FIG. 1. The drawings provided here are for illustration purposes only, and the equipment diagram does not limit the content presented in the present disclosure.

FIG. 1 is a basic device schematic view for preparing high-purity lithium chloride through lithium-ion ceramic electrolyte. The shape of the device includes but is not limited to cylindrical or square. The anode and cathode and their related parts can be interchanged. The device is a single structure and can be connected in series or parallel through external pipelines of the same type. It is used to prepare high-purity lithium chloride through a principle similar to fractional distillation. The cathode product of the device can be further purified by physical or chemical methods.

In FIG. 1, 1 represents the device housing, which is made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic film, and other alloys. An example material for the housing is alloy steel shell, such as 304 or 316 stainless steel shell.

In FIG. 1, 2 represents the cathode chamber, which mainly serves to store molten cathode salts, such as lithium chloride/aluminum chloride or lithium chloride/zinc chloride.

In FIG. 1, 3 represents the anode chamber, which serves to store molten anode salts composed of one or more chloride additives, such as lithium chloride salt of low purity, AlCl₃, MgCl₂, NaCl, FeCl₂, and ZnCl₂. The low-purity lithium chloride salt can be obtained from salt lakes, salt wells, seawater, or lithium mines, with a purity ranging from 1 wt%-98 wt%. The molten anode salts also contain one or more of the chloride additives such as AlCl₃, MgCl₂, FeCl₂, and ZnCl₂, which are used to lower the melting point of the molten salts.

In FIG. 1, 4 represents the molten cathode salt output pipeline, which is made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic film, and other alloys. An example material for the pipeline is alloy steel shell, such as 304 or 316 stainless steel shell. The function of the molten cathode salt output pipeline is to provide a channel for purified molten cathode salt to be discharged.

In FIG. 1, 5 represents the molten cathode salt input pipeline, which is made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic film, and other alloys. An example material for the pipeline is alloy steel shell, such as 304 or 316 stainless steel shell. The function of the molten cathode salt input pipeline is to provide a channel for unpurified molten cathode salt to be input into the cathode chamber.

In FIG. 1, 6 represents the cathode electrode input/extract pipeline, which is made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic film, and other alloys. An example material for the pipeline is alloy steel shell, such as 304 or 316 stainless steel shell. The function of the cathode electrode input/extract pipeline is to insert/extract the cathode electrode into/out of the cathode chamber.

In FIG. 1, 7 represents the molten anode salt input pipe, which can be made of materials such as metal, high-temperature resistant non-metal, or organic polymer, including but not limited to steel shell, aluminum shell, aluminum-plastic film, and other alloys. In some embodiments, an alloy steel shell such as 304 or 316 stainless steel shell is used. The function of the molten anode salt input pipe is to provide a passage for the further purified molten anode salt to be introduced into the anode chamber.

In FIG. 1, 8 represents the molten anode salt output pipe, which can be made of various materials including but not limited to metals, high-temperature-resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. In some embodiments, it is made of alloy steel shells such as 304 and 316 stainless steel shell. The function of the molten anode salt output pipe is to provide a pathway for the purified molten anode salt to be discharged or for the outlet of the aluminum chloride gas generated by the molten anode salt at the device temperature.

In FIG. 1, 9 represents the anode electrode input/insertion pipe, which can be made of various materials including but not limited to metals, high-temperature resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. Example materials are alloy steel shells like 304 and 316 stainless steel shell. The function of the anode electrode input/insertion pipe is to insert or extract the anode conductor or sacrificial material from the anode chamber.

In FIG. 1, 10 represents the cathode electrode composed of a metal or inert electrode, which is externally connected to the negative terminal of the external power source and in contact with the molten cathode reactant internally. It maintains electronic insulation with parts 1 and 8 in FIG. 1. The material properties require high electrical conductivity, good chemical stability without chemical reactions with the cathode material, such as copper, zinc, aluminum, stainless steel, copper alloys, graphite, or combinations of these materials, such as aluminum or zinc. Its function is to provide an electron pathway, provide an interface field for the generation of aluminum/zinc reaction, and provide a field for the accumulation of aluminum or zinc.

In FIG. 1, 11 represents the anode conductor and sacrificial anode, typically made of pure metals such as aluminum or zinc that can react with the molten salt. The anode conductor externally connects to the positive terminal of the external power supply, and internally connects is to the molten anode salt. It maintains electronic insulation with parts 1 and 9 in FIG. 1. In some embodiments, the sacrificial anode may be made of a different material from the anode conductor, such as zinc or other pure metal and is in contact with the molten cathode reactant. The anode conductor portion can be made of a combination of zinc, aluminum, stainless steel, copper alloy, graphite, or any combination of these materials and externally connected to the positive terminal of the external power supply. The anode conductor and sacrificial material can be joined together by welding, mesh wrapping, cylinder nesting, or other methods.

In FIG. 1, 12 represents the lithium-ion ceramic electrolyte, which can be made of a combination of oxides, phosphates, sulfides or any of the aforementioned materials that allow only lithium ions to pass through. The ceramic electrolyte acts as a separator that allows only lithium ions to pass through, preventing other ions from passing through, and also acts as a membrane to prevent the mixing of substances between the two electrodes. The solid-state electrolyte separates the molten cathode salt and molten anode salt. The shape of the ceramic solid electrolyte includes, but is not limited to, sheet, tube, box, and other shapes. In some embodiments, the garnet-type oxide Li_7-xLa₃Zr_2-xTa_xO₁₂ solid electrolyte is selected, where X can be chosen from 0-1.0; it has a cross-sectional thickness from 0.01cm to 2.0cm; and a relative density from 85%to 99.9%.

The molten cathode salt is a mixture of purified lithium chloride and aluminum chloride, with a mass ratio of LiCl: (AlCl₃+LiCl) in the range of 0-99%, or 19.3-24.8%. With this ratio, the molten cathode salt can be more fully melted, which is conducive to reducing ion diffusion resistance, lowering polarization voltage, and improving energy efficiency during operation.

In FIG. 1, 13 is the condenser, which functions to liquefy the aluminum chloride gas discharged from the pipe 8 in FIG. 1.

In FIG. 1, 14 represents the shell of the collection device for the discharged molten anodic salt or cooled aluminum chloride liquid. The material of the shell includes but is not limited to metal, high-temperature resistant non-metal, and organic polymer, such as steel shell, aluminum shell, aluminum plastic film, alloy steel shells such as 304 and 316 stainless steel shell, and other alloys.

In FIG. 1, 15 represents the discharge pipeline, which is made of materials including but not limited to metals, high-temperature resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. Alloy steel shells such as 304 and 316 stainless steel shells may be employed. The function of the discharge pipeline is to discharge the collected molten anode salt or cooled aluminum chloride liquid from 14 in FIG. 1 for further processing or recycling.

In FIG. 1, 16 represents the outer shell of the lithium chloride collection device in the molten cathodic salt, which can be made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymer, such as steel shell, aluminum shell, aluminum plastic film, and other alloys. Alloy steel shells such as 304 and 316 stainless steel shells may be used.

In FIG. 1, 17 represents a filter screen, which can be made of various materials including but not limited to metals, high-temperature resistant non-metals, organic polymers, and other alloys. The function of the filter screen is to filter out and enrich the lithium chloride particles generated in the molten cathode salt, to collect them as products.

In FIG. 1, 18 represents the discharge pipe, which is made of materials including but not limited to metal, high-temperature resistant non-metal, organic polymer, such as steel shell, aluminum shell, aluminum-plastic film, and other alloys. Alloy steel shells such as 304 and 316 stainless steel shell may be used. The function of the discharge pipe is to discharge the molten cathode salt after the chloride lithium particles have been filtered out in 17 of FIG. 1.

In FIG. 1, 19 represents the outer shell of the molten cathode salt collection device, which can be made of materials including but not limited to metals, high-temperature resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, alloy steel shells such as 304 and 316 stainless steel shell, and other alloys.

In FIG. 1, 20 represents the discharge pipeline, which can be made of various materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shell, aluminum shell, aluminum-plastic film, and other alloys. Example materials are alloy steel shell such as 304 and 316 stainless steel shell. The function of the discharge pipeline is to discharge the molten cathode salt collected by 18 in FIG. 1 for further processing or recycling.

In FIG. 1, 21 represents a high-temperature valve, which provides sealing function and controls the material flow rate.

The various connecting parts in FIG. 1 can be sealed with inorganic aluminosilicate, alumina-based high-temperature adhesive, sealing glass, and partially with organic high-temperature adhesive, or by welding. The suitable temperature range for high-temperature adhesive is between 100℃-1000℃, or 200℃-400℃. The adhesive should be capable of long-term use in this temperature range without chemical reactions with the positive and negative electrode materials, self-degradation, or cracking due to temperature changes.

The device shown in FIG. 1 can be placed in a high-temperature oven or other external heating device during actual use, or an internal component for heating can be added to Device 1, and maintained in a heated state during use to ensure the electrolyte salt is melted. For example, under working conditions, the temperature of Device 1 can be less than 800 ℃, less than 500 ℃, less than 400 ℃, less than 300℃, or less than 250℃, and higher than the melting point of the salt.

In practical use, an external current needs to be applied to the anode and cathode of the device 1 to ensure the progress of the purification reaction.

The method for removing aluminum chloride from lithium chloride collected on the cathode side includes high-temperature distillation and electrochemical electrolysis. The melting point of aluminum chloride is 194℃ and its boiling point is 178 ℃ at atmospheric pressure, while the melting point of lithium chloride is 605 ℃ and its boiling point is 1383℃ at atmospheric pressure. The distillation method is based on the difference in boiling points between lithium chloride and aluminum chloride to separate them. The principle of electrochemical electrolysis is based on the fact that the decomposition voltage of aluminum chloride is much lower than that of lithium chloride, so the residual aluminum chloride in lithium chloride can be removed by electrolysis. In the present disclosure, negative pressure distillation is employed as the method for removing aluminum chloride.

The device shown in FIG. 2 is used to further process the purified lithium chloride collected from the cathode in FIG. 1 using negative pressure distillation to remove the aluminum chloride and obtain high-purity lithium chloride.

In FIG. 2, 22 represents the material input of purified molten lithium chloride collected from the cathode in FIG. 1. The material of the pipe includes but is not limited to metals, high-temperature resistant non-metals, organic polymers, such as steel shells, aluminum shells, aluminum plastic films, and other alloys. Example material is alloyed steel shell such as 304 and 316 stainless steel shell.

In FIG. 2, 23 represents the outer shell, which can be made of various materials including but not limited to metals, high-temperature resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. Alloy steel shells, such as 304 and 316 stainless steel shells, may be used. The function of the outer shell is to provide storage space for the molten salt input in 22 of FIG. 2 and provide physical space for distillation to occur.

In FIG. 2, 24 represents the outlet pipeline, which can be made of materials including but not limited to metal, high-temperature resistant non-metal, and organic polymers, such as steel shell, aluminum shell, aluminum-plastic film, and other alloys. Example materials are alloy steel shells such as 304 and 316 stainless steel shell. The function of the outlet pipeline is to discharge the aluminum chloride gas generated by 23 in FIG. 2.

In FIG. 2, 25 represents an outlet pipe, which can be made of materials including but not limited to metal, high-temperature-resistant non-metal, and organic polymers such as steel, aluminum, aluminum-plastic film, and other alloys. In some embodiments, the material is an alloy steel shell such as 304 or 316 stainless steel shell. The function of the outlet pipe is to discharge the high-purity lithium chloride produced in the 23 of FIG. 2.

In FIG. 2, 26 represents a condenser, which is used to condense the aluminum chloride gas discharged from the pipeline 24 in FIG. 2.

In FIG. 2, 27 represents the outer shell, which can be made of various materials including but not limited to metal, high-temperature resistant non-metal, organic polymers, such as steel shell, aluminum shell, aluminum-plastic film, and other alloys. The example material is alloy steel shell such as 304, 316 stainless steel. Its function is to provide storage space for the input of liquid aluminum chloride.

In FIG. 2, 28 represents the vacuum negative pressure pipeline, which is made of materials including but not limited to metals, high-temperature resistant non-metals, and organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. The example material is alloy steel shell, such as 304 and 316 stainless steel shell. The function of the vacuum negative pressure pipeline is to vacuum the device and maintain negative pressure to accelerate the discharge of aluminum chloride gas.

In FIG. 2, 29 represents the discharge pipeline. Its material includes, but is not limited to, metals, high-temperature resistant non-metals, organic polymers, such as steel shells, aluminum shells, aluminum-plastic films, and other alloys. Example materials are alloy steel shells such as 304 and 316 stainless steel shell. The function of the discharge pipeline is to discharge liquid aluminum chloride generated in 27 of FIG. 2 for further processing or recycling.

In FIG. 2, 30 represents a high-temperature valve, which can be added at an appropriate location in the device. Its function is to provide sealing and control the material flow rate.

The various connecting parts in FIG. 2 can be sealed using inorganic alumino-silicate, aluminum oxide high-temperature adhesive, sealing glass, or partially organic high-temperature adhesive. Welding can also be used for sealing. The suitable temperature range for the high- temperature adhesive is between 100℃-1500℃ , or 200℃-800℃. The adhesive should be chemically stable, not react with the molten salt, not degrade over time, and not crack due to temperature changes.

During actual operation, the device shown in FIG. 2 can be placed in an external heating device such as a high-temperature oven, or heating elements can be added inside the device to provide heating, and the heating state should be maintained during use to ensure the electrolyte's melting. For example, under working conditions, the temperature of device 22 can be less than 800℃ , less than 500℃ , less than 400℃ , less than 300℃, or less than 250℃, while still higher than the melting point of the electrolyte.

A method and apparatus for high-purity lithium chloride purification based on lithium-ion solid-state electrolyte. The apparatus comprises an anode/cathode conductor, sacrificial anode electrode, anode melt containing low-purity lithium chloride salt that allows only lithium ions to pass through the solid-state electrolyte, cathode melt containing lithium chloride and other metal chloride, and a shell covering the above components. The entire apparatus needs to be heated during use and an external circuit needs to be connected. The apparatus forms an electrolytic cell, and during high-temperature electrification, the sacrificial anode electrode is oxidized, and the corresponding metal ions enter the anode melt. The lithium ions in the anode melt enter the cathode melt through the solid-state electrolyte, and the aluminum ions or zinc ions in the cathode melt are reduced to metal and deposited on the cathode electrode, leaving chloride ions to combine with the lithium ions that have been conducted over to form lithium chloride.

The temperature range for the reaction process can be defined as 100℃-1000℃, or 200℃-400℃ or 250℃, 300℃, 320℃, 350℃, 380℃, or between any two of the above numbers.

The reaction voltage is 0-4V or 0.5-1.5V or 0.5V, 0.8V, 1.0V, 1.2V or between any two of the above values.

The material of the anode and cathode, the composition and proportion of the anode and molten cathode salts, the material of the shell, and the material of the pipes are all within the scope of protection provided by the data and content in the instruction manual.

Example 2

The LiCl purification device was assembled using stainless steel for the outer shell and pipelines, and LLZTO sheet-type electrolyte with a molecular formula of Li_6.4La₃Zr_1.4Ta_0.6O₁₂, a cross-sectional thickness of 4.2mm, and a relative density of 90%. Both the anode and cathode were made of aluminum. The anode initially contained a mixture of salt weighing 1960g, with mass ratios of LiCl, NaCl, KCl, MgCl₂, and AlCl₃ being 2.04%, 4.59%, 4.97%, 13.39%, and 75.00%, respectively. Excluding the weight of the solubilizer AlCl₃, the mass ratios of LiCl, NaCl, KCl, and MgCl₂ in the salt mixture were 8.17%, 18.37%, 19.90%, and 53.56%, respectively. The cathode initially contained a mixture of salt weighing 650g, with mass ratios of LiCl and AlCl₃ being 24.00%and 76.00%, respectively. The device was heated to 200℃and powered-on. The relationship between the current density and voltage is shown in FIG. 3. At a current density of 25mA/cm², the voltage was 0.40V. At a current density of 50mA/cm², the voltage was 0.59V. At a current density of 100mA/cm², the voltage was 0.999V. A total of 4772.52mAh of electric charge was passed through the device. Table 2 shows the composition of the anode and cathode before and after charging. It can be seen that during the electrolysis process, most of the ions that passed from the anode to the cathode through the LLZTO electrolyte sheet were lithium ions, with only a small number of impurity ions such as Na, K, and Mg, indicating an effective purification of LiCl from low to high concentrations.

After the electrolysis, the molten cathode salt is transferred to a separation device for aluminum chloride and lithium chloride. The mixture is then subjected to vacuum distillation at 300℃ and 0.01MPa to remove the aluminum chloride, leaving behind highly pure lithium chloride with a purity of 99.83 wt%. The removed aluminum chloride is collected after condensation and can be reused.

Table 2 shows the content of each substance in the cathode before and after electrolysis.

Example 3

The extraction device for LiCl was assembled using a stainless steel shell and pipeline, with LLZTO sheet electrolyte (Li_6.8La₃Zr_1.8Ta_0.2O₁₂) having a cross-sectional thickness of 3.4 mm and a relative density of 91%. The anode and cathode were both made of aluminum. Initially, the anode contained a mixture of salt weighing 895.55g, with the mass ratios of LiCl, NaCl, KCl, MgCl₂, and AlCl₃ being 10.70%, 9.26%, 2.41%, 2.32%, and 75.31%, respectively. Excluding the mass of AlCl₃, the mass ratios of LiCl, NaCl, KCl, and MgCl₂ in the salt were 43.34%, 37.51%, 9.75%, and 9.40%, respectively. The cathode initially contained a mixture of salts weighing 600g, with the mass ratios of LiCl and AlCl3 being 22.00%and 78.00%, respectively. The device was charged using a current density of 100 mA/cm² at 200℃ in a high-temperature oven, resulting in a voltage of 0.93V due to polarization. The charging capacity was 4492.56 mAh, and the contents of various substances in the cathode before and after the current was applied are shown in Table 3. It can be seen that during the electrolysis process, the vast majority of the substances that passed from the molten anode salt through the LLZTO electrolyte sheet and entered the molten cathode salt were lithium ions, with only a very small number of impurity ions such as Na, K, and Mg, demonstrating the purification effect from low-concentration LiCl to high-concentration LiCl.

After electrolysis, transfer the molten cathode salt to the AlCl₃ and LiCl separation device, in which the molten cathode salt is subjected to a 300℃-0.01MPa reduced-pressure distillation to remove AlCl₃ and obtain 99.87 wt%purity LiCl. The removed AlCl₃ is condensed and collected for reuse.

Table 3 shows the content of each substance in the cathode before and after electrolysis.

Example 4

Stainless steel was used for the shell and pipes, and LLZTO plate electrolyte was employed, with the chemical formula Li_6.5La₃Zr_1.5Ta_0.5O₁₂, a cross-sectional thickness of 2.8mm, and a relative density of 93%. The anode and cathode were both made of aluminum, and a LiCl extraction device was assembled. The initial mixed salt for the anode weights 876.08g, with mass ratios of LiCl, NaCl, KCl, MgCl₂, and AlCl₃ being 18.03%, 1.55%, 3.90%, 1.51%, and 75.01%, respectively. Excluding the mass of AlCl₃ as the solvent, the mass ratios of LiCl, NaCl, KCl, and MgCl₂ in the mixed salt were 72.15%, 6.19%, 15.61%, and 6.05%, respectively. The initial mixed salt for the cathode weights 500g, with a mass ratio of LiCl and AlCl₃ being 19.50%and 80.50%, respectively. The device was subjected to a current density of 100mA/cm² at 200℃ in a high-temperature oven, with a resulting voltage of 0.89V due to polarization. The charge was 4727.27mAh, and the content of each substance in the cathode before and after electrolysis is shown in Table 4. It is evident that during the electrolysis process, the vast majority of ions entering the molten cathode salt through the LLZTO electrolyte plate from the molten anode salt were lithium ions, with only a small amount of impurity ions such as Na, K, and Mg, which demonstrates the purification effect from low-concentration LiCl to high-concentration LiCl.

After electrolysis, transfer the molten cathode salt to the equipment for separating AlCl₃ and LiCl, in which the molten cathode salt is subjected to a pressure reduction distillation at 300℃-0.01MPa to obtain LiCl with a purity of 99.99 wt%. The removed AlCl₃ is collected after condensation and reused.

Table 4 shows the content of each substance in the cathode before and after electrolysis .

Example 5

Stainless steel shell and pipes are used to assemble a LiCl extraction device, which utilizes LATP (Li_1.3Al_0.3Ti_1.7 (PO₄) ₃) as a sheet-like electrolyte with a cross-sectional thickness of 5.0mm and a relative density of 93%. The anode and cathode are both made of aluminum. The anode initially contains a mixture of salt, with a mass ratio of LiCl, NaCl, KCl, MgCl₂, and AlCl₃ being 12.25%, 6.70%, 2.21%, 2.94%, and 75.90%, respectively, and excluding the mass of AlCl₃. Thus, the mass ratio of LiCl, NaCl, KCl, and MgCl₂ in the salt is 50.85%, 27.80%, 9.15%, and 12.20%, respectively. The cathode initially contains a mixture of LiCl and AlCl₃, with a mass ratio of 24.00%and 76.00%, respectively. When the device is powered at 200℃, the relationship between current density and voltage is shown in FIG. 3. When the current density is 25mA/cm², the voltage is 0.40V; when the current density is 50mA/cm², the voltage is 0.59V; when the current density is 100mA/cm², the voltage is 0.999V. A total of 4772.52mAh of electricity was passed through the device. The contents of the various substances in the cathode before and after electrolysis are shown in Table 5, indicating that the purification effect from low-concentration LiCl to high-concentration LiCl is achieved, and the majority of the impurity ions that pass through the LATP electrolyte sheet from the molten anode salt into the molten cathode salt are lithium ions, with only a few Na, K, and Mg impurity ions.

After electrolysis, translate the molten cathode salt to a separation device for aluminum chloride and lithium chloride. After a reduced-pressure distillation under 300℃-0.01MP, the AlCl₃ was removed, and a 99.85 wt%purity LiCl was obtained. The collected AlCl₃ was condensed and reused.

Table 5 shows the content of each substance in the cathode before and after electrolysis.

Compared with traditional methods of preparing LiCl by first preparing LiOH and then using Cl₂ or hydrochloric acid, the technology in this example is more environmentally friendly, has lower purification voltage, and lower production cost.

Claims

A device for preparing high-purity lithium chloride, comprising a cathode chamber, an anode chamber, and lithium-ion ceramic electrolyte, wherein:

the cathode chamber is configured for storing molten cathode salt,

the anode chamber is configured for storing low-purity lithium chloride salt with a purity of 1 wt%-98 wt%,

the lithium-ion ceramic electrolyte is placed between the cathode chamber and the anode chamber, the lithium-ion ceramic electrolyte serves as both an electrolyte that only allows lithium ions to pass through and a diaphragm to prevent material mixing between the cathode chamber and the anode chamber.
The device according to claim 1, wherein the lithium-ion ceramic electrolyte is selected from the garnet-type oxide Li_7-xLa₃Zr_2-xTa_xO₁₂ , where x is selected from 0-1.0; a thickness of the lithium-ion ceramic electrolyte is from 0.01 cm to 2.0 cm; and a relative density is from 85%-99.9%.
The device according to claim 1 or 2, wherein the cathode molten salt comprises lithium chloride/aluminum chloride or lithium chloride/zinc chloride .
The device according to any one of claims 1 to 3, wherein the molten cathode salt is a mixed salt of lithium chloride and aluminum chloride or a mix of lithium chloride and zinc chloride, whe re i n a molar ratio of LiCl to (AlCl₃+LiCl) in the mixed salt is in the range of 0 to 0.99.
The device according to claim 4, whe re i n th e molar ratio of LiCl to (AlCl₃+LiCl) in the mixed salt is in the range of 0.43 to 0.51.
A method for preparing high-purity lithium chloride through lithium-ion ceramic electrolyte, the method comprising:

adding low-purity lithium chloride salt as anode salt in an anode chamber of a reaction vessel, where a purity of the low-purity lithium chloride salt is 1 wt%-98 wt%; .

adding a cathode salt to a cathode chamber of the reaction vessel, wherein the cathode salt includes LiCl/AlCl₃ or LiCl/ZnCl₂;

providing a lithium-ion ceramic electrolyte between the cathode chamber and the anode chamber, wherein the lithium-ion ceramic electrolyte serves as both an electrolyte that only allows lithium ions to pass through and a diaphragm to prevent material mixing between the cathode chamber and the anode chamber;

heating the reaction vessel at a temperature higher than a melting point of the low-purity lithium chloride salt and the cathode salt; .

applying an electric current to the reaction vessel , with a current density of 1-500 mA/cm² and a voltage of 0-4V;

separating LiCl from AlCl₃ or separating LiCl from ZnCl₂ of the cathode molten salt at a separation device, and obtaining high-purity LiCl with a purity of more than 99 wt%.
The method according to claim 6, wherein the current density is 50-150 mA/cm².
The method according to claim 6, wherein the voltage is 0-1.5V.
The method according to claim 6, wherein the temperature is 100℃-1000℃.
The method according to claim 9, wherein the temperature is 200℃-400℃.
The method according to claim 6, wherein the separation device uses vacuum distillation to remove AlCl₃, . wherein conditions for the vacuum distillation include: at a temperature range of 100℃-1000℃, . and at a pressure of is less than or equal to 0.1 MPa.
The method according to claim 11, wherein the conditions for the vacuum distillation include: at a temperature range of 200℃-400℃ and at a pressure between 0.05 MPa and -0.05 MPa.
The method according to claim 6, wherein the separation device uses an electrochemical electrolysis method to remove AlCl₃.
The method according to claim 6, wherein the low-purity lithium chloride salt is sourced from one of salt lakes, salt mines, seawater, or lithium mines.