A production device and method for battery-grade lithium acetate

Abstract

The present invention proposes a device and method for producing battery-grade lithium acetate. The device is composed of a feed mixing tank, a BPED double decomposition membrane stack, a primary evaporator, a BaSO4 precipitator and a vacuum evaporator. The production method is as follows: prepare a mixed solution of Li2SO4 and acetic acid as an initial alkali chamber solution; introduce pure water and the initial alkali chamber solution into the BPED membrane stack to undergo double decomposition reaction to obtain a crude LiAc solution and a H2SO4 byproduct solution; evaporate and concentrate the crude LiAc solution once to obtain Li2SO4·H2O crystals and a purified LiAc solution; add a BaAc2 solution to the purified LiAc solution to completely remove the residual Li2SO4 impurities to obtain a battery-grade LiAc solution; and vacuum evaporate and dry the battery-grade LiAc solution. The present invention realizes the direct preparation of a high-purity, high-value anhydrous LiAc solid product from cheap raw materials, greatly reduces the production cost of LiAc products, and can expand its wide application in the downstream battery industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of organic acid lithium salts, and in particular relates to a device and method for producing battery-grade lithium acetate upstream of a lithium-ion battery. Background Art

[0002] Lithium acetate is one of the important raw materials in the lithium-ion battery industry and has broad application prospects in the industry. At present, the main method for preparing lithium acetate is the neutralization method, that is, using lithium hydroxide or lithium carbonate as a lithium source, neutralizing it with acetic acid to obtain a lithium acetate solution, and then obtaining lithium acetate solid by evaporation, concentration and crystallization. In actual production (such as Chinese patent CN103739475B), in order to maximize the concentration of the obtained lithium acetate solution while avoiding the generation of a large number of bubbles, it is generally necessary to preferably use lithium hydroxide as a raw material.

[0003] At present, the main sources of lithium primary resource extraction are salt lake brine and solid lithium ore. Strictly speaking, all downstream lithium resource products come from this. In the process of lithium extraction from ore, the initial extracted product is Li2SO4, which is further converted into other lithium salt products. For example, in order to obtain Li2CO3 products, Na2CO3 needs to be added to these initial Li2SO4 solutions to precipitate the lithium resources in the form of Li2CO3. However, this process has the following problems: (1) The use of a large amount of Na2CO3 chemicals, especially in remote areas where salt lakes and lithium mines are located, has a high transportation cost. (2) This process produces a large amount of Na2SO4 solution byproducts that cannot be discharged directly. It needs to be evaporated and heated to obtain anhydrous sodium sulfate (sodium sulfate) solid products, which is energy-intensive and has a small market demand, further increasing the cost. (3) In order to remove the impurities remaining in the Li2CO3 solid, a large amount of pure water is required to wash the filter cake, resulting in the consumption of water resources and the generation of a large amount of washing wastewater, which has caused great difficulties in water-scarce salt lakes or lithium mining areas. (4) Since the solubility of Li2CO3 solid in water is relatively high (13.3 g / L at 20 °C), this inevitably leads to incomplete precipitation of Li2CO3 and a high lithium loss rate during the washing process. As a downstream product, LiOH is even more difficult to obtain. The current mainstream LiOH preparation uses the causticization method, which uses Li2CO3 and Ca(OH)2 as raw materials to produce LiOH, and its reaction equation is Li2CO3 + Ca(OH)2 → 2LiOH + CaCO3↓. This process requires the use of high-cost Li2CO3 as a raw material, the introduction of additional chemicals, and a cumbersome subsequent solid-liquid separation process, and finally produces a large amount of CaCO3 waste residue. This synthetic route, which is neither economical nor environmentally friendly, results in the product prices of Li2CO3 and LiOH being significantly higher than Li2SO4. Therefore, the traditional lithium acetate preparation method based on Li2CO3 or LiOH makes lithium acetate products difficult to obtain and has high production costs, which greatly limits its widespread application in downstream industries.

[0004] If we consider the raw material cost and availability of lithium acetate products, Li2SO4 is an ideal lithium source, while acetic acid (HAc) is an ideal source of acetate. Although acetic acid can be produced by biological fermentation, the industry tends to use cheaper methanol and carbon monoxide to directly carbonylate it. Because the raw materials are simple and easy to obtain and the production process is mature and stable, the production scale of acetic acid is huge (~10 7 Tons / year) and low cost. If a new production process can be developed to directly use acetic acid and Li2SO4 as raw materials to produce high-purity lithium acetate products, it will undoubtedly have huge economic value. It can not only fundamentally reduce its production cost, but also greatly broaden and accelerate its downstream applications. Summary of the invention

[0005] The object of the present invention is to provide a production device and method for battery-grade lithium acetate.

[0006] The present invention provides a battery-grade lithium acetate production device, which can use HAc and Li2SO4 as raw materials to produce battery-grade high-purity lithium acetate. The device consists of a feed mixing tank, a BPED (bipolar membrane electrodialysis) double decomposition membrane stack, a primary evaporator, a BaSO4 precipitator and a vacuum evaporator connected by pipelines. The feed mixing tank is connected to the alkali chamber inlet of the BPED double decomposition membrane stack, the alkali chamber outlet of the BPED double decomposition membrane stack is connected to the liquid inlet of the primary evaporator, the crystallized solid outlet of the primary evaporator is connected to the inlet of the feed mixing tank, and the solution outlet of the primary evaporator is connected to the inlet of the BaSO4 precipitator, and the solution outlet of the BaSO4 precipitator is connected to the inlet of the vacuum evaporator.

[0007] In the present invention, the distilled water outlets of the primary evaporator and the vacuum evaporator are connected to the pure water inlet of the feed mixing tank.

[0008] In the present invention, the BPED double decomposition membrane stack adopts a two-compartment configuration of a bipolar membrane + a female mold to form independent acid chamber and alkali chamber flow channels, and the acid and alkali chamber solutions circulate in their corresponding flow channels respectively.

[0009] In the present invention, BaSO4 is used in the BaSO4 precipitator. 2+ Ion selective electrodes precisely control the feed ratio.

[0010] The present invention provides a method for producing battery-grade lithium acetate, which mainly comprises the following steps:

[0011] (1) Prepare a mixture of Li2SO4 and acetic acid (HAc) as the initial alkaline chamber solution, where Li + The concentration range is 0.50–3.0 mol / L, Li + The concentration ratio of HAc is 90–130%; pure water is used as the initial acid chamber solution and passed into the BPED double decomposition membrane stack of the bipolar membrane electrodialyzer.

[0012] The BPED double decomposition membrane stack adopts a bipolar membrane + female mold two-compartment configuration to form independent acid chamber and base chamber flow channels, and the acid and base chamber solutions circulate in their corresponding flow channels respectively. Under the action of the electric field, water molecules dissociate and convert into H + and OH – ions. Among them, OH – ions enter the base chamber. Since the base chamber is originally acidic (Li2SO4 + HAc), these OH – It will immediately react with the free H + The compound generates water molecules, and the alkali room does not produce OH –When all the free H + The operation is completed when the pH rises to 6–10. 2– ) relative to the organic anion (Ac – ) is the key. Since the main material of the ion exchange membrane is organic hydrocarbons, organic ions (such as Ac – ) tend to have a higher transport resistance in the membrane than inorganic ions (such as SO4 2– ) is larger, which leads to significant inorganic ion selectivity when the two compete for transmembrane transport. 2– and free Ac – ) moves toward the positive electrode under the driving of the electric field. In the process of penetrating the anion exchange membrane (AEM), the inorganic anion SO4 2– The transport resistance is significantly lower than that of organic anions Ac – , so SO4 2– The H produced by hydrolysis in the bipolar membrane will preferentially pass through the AEM to the acid chamber. + ions also migrate into the acid chamber and interact with the SO4 2– Combined to form H2SO4 byproduct solution. The net effect is that the mixed solution of Li2SO4 and HAc in the alkaline chamber loses the H2SO4 component and gradually converts into lithium acetate (LiAc) product solution. That is, under the action of the DC electric field, a double decomposition reaction occurs: Li2SO4 + 2HAc → 2LiAc +H2SO4, directly obtaining a crude LiAc solution and an H2SO4 byproduct solution; the H2SO4 byproduct solution can be directly recycled to the lithium ore leaching section and converted back into Li2SO4 so that the sulfate material can be completely reused;

[0013] (2) The crude LiAc solution obtained in step (1) is passed into a primary evaporator for evaporation, concentration and crystallization to obtain Li2SO4·H2O solid and LiAc purified solution. The Li2SO4·H2O solid is recycled to prepare the initial alkali chamber solution. The evaporation temperature is 60–110°C. As the water in the solution evaporates, the concentrations of LiAc and Li2SO4 both increase; however, due to the common ion effect (the two components contain the same cation Li + ), the large amount of Li in LiAc +It will reduce the solubility of Li2SO4 in this system, causing the low-concentration Li2SO4 component to saturate and precipitate first in this process (also known as the salting-out effect). At this time, the liquid phase component is a purified LiAc purification liquid, and the solid phase is pure Li2SO4·H2O crystals. After solid-liquid separation, the solid can be directly reused for the preparation of the initial alkali chamber liquid of BPED. The evaporation temperature in this process is 60–110°C; the final LiAc concentration is 8–11 mol / L. The concentration of residual Li2SO4 impurities in the LiAc solution after preliminary purification is greatly reduced (as low as ~0.7% of the LiAc concentration);

[0014] (3) Pass the LiAc purified solution obtained in step (2) into a BaSO4 precipitator, add BaAc2 solution, and use barium acetate to precipitate the SO4 2– ions, the chemical reaction equation is Li2SO4 + BaAc2 → 2LiAc + BaSO4↓. In this process, the residual SO4 2– The concentration of Ba 2+ The ion selective electrode performs real-time monitoring and control to ensure that the dosage of BaAc2 is in a stoichiometric ratio with Li2SO4. After precise filtration to remove the BaSO4 precipitate, a LiAc solution product with battery-grade purity (Li2SO4 impurity <0.01%) can be obtained. 2+ and SO4 2– The concentrations were all below 2 mg / L;

[0015] (4) The battery-grade LiAc product solution obtained in step (3) is completely evaporated to dryness and subsequently dehydrated and dried in a vacuum evaporator. The temperature is controlled at 100-150°C and the vacuum degree is ≤0.08 MPa. After vacuum evaporation and drying, a battery-grade anhydrous LiAc solid is obtained. After cooling and crushing, the final product is packaged.

[0016] In the present invention, the pH range of the alkaline chamber solution operation termination of the BPED double decomposition membrane stack in step (1) is preferably 6.5-8.0.

[0017] In the present invention, the evaporation temperature in the primary evaporator in step (2) is 80-100°C.

[0018] The beneficial effects of the present invention are:

[0019] 1. The device and method of the present invention directly realize the double decomposition reaction Li2SO4 +2HAc → 2LiAc + H2SO4 without any additional reactants, and the reaction products are in two independent liquid products without the need for additional separation operations. The reaction cannot occur spontaneously thermodynamically because it involves the reaction of a weak acid (HAc) to produce a strong acid (H2SO4); secondly, even if the above reaction can occur, the final products LiAc and H2SO4 are highly soluble in water, and it is very difficult to separate the final LiAc product from their mixed solution. In the present invention, the cost of making the above reaction occur is only the input of electrical power;

[0020] 2. In the present invention, subsequent purification is achieved only by a purely physical method of evaporation and crystallization, and the recovered Li2SO4·H2O solid can be directly reused; only the final deep purification step requires the additional addition of the chemical BaAc2, but at this time the residual Li2SO4 concentration is very low, the amount of consumed chemicals is greatly reduced, and the purification efficiency is high;

[0021] 3. In the present invention, all materials (including Li + , SO4 2– , H + and Ac – ) Either completely converted into the final LiAc product or completely recycled, with high atom economy and environmental friendliness;

[0022] 4. The device and method of the present invention can directly prepare high-purity and high-value anhydrous LiAc solid products from cheap raw materials (Li2SO4 and acetic acid), which can greatly reduce the production cost of LiAc products. At the same time, it can be directly used in the battery industry and expand its downstream applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the production device of battery-grade lithium acetate of the present invention, wherein 1 is a feed mixing tank, 2 is a BPED double decomposition membrane stack, 3 is a primary evaporator, 4 is a BaSO4 precipitator, and 5 is a vacuum evaporator.

[0024] Figure 2 Schematic diagram of the internal structure and material migration of the BPED double decomposition membrane stack, where a is the basic repeating unit of the membrane stack, b is the bipolar membrane, c is the anion exchange membrane, and d is the cation exchange membrane.

[0025] Figure 3 The typical evolution diagram of the crude LiAc solution obtained by BPED metathesis in the primary evaporator 3, where curve a is the LiAc (Ac – ) concentration change curve, b is Li2SO4 (SO4 2– ) concentration change curve, c is the purity of LiAc (expressed as [Ac –] / [SO4 2– ]) change curve.

[0026] Figure 4 This is the powder X-ray diffraction (XRD) spectrum of the crystalline solid produced in the primary evaporator 3 in Example 4. DETAILED DESCRIPTION

[0027] The present invention will be further described in the following examples, but the present invention is not limited thereto.

[0028] Embodiment 1:

[0029] like Figure 1 As shown, a production device for battery-grade lithium acetate is composed of a feed mixing tank 1, a BPED (bipolar membrane electrodialysis) double decomposition membrane stack 2, a primary evaporator 3, a BaSO4 precipitator 4 and a vacuum evaporator 5 connected by pipelines. The feed mixing tank 1 is connected to the alkali chamber inlet of the BPED double decomposition membrane stack 2, the alkali chamber outlet of the BPED double decomposition membrane stack 2 is connected to the liquid inlet of the primary evaporator 3, the crystallized solid outlet of the primary evaporator 3 is connected to the inlet of the feed mixing tank 1, and the solution outlet of the primary evaporator 3 is connected to the inlet of the BaSO4 precipitator 4, the solution outlet of the BaSO4 precipitator 4 is connected to the inlet of the vacuum evaporator 5, and the distilled water outlets of the primary evaporator 3 and the vacuum evaporator 5 are connected to the pure water inlet of the feed mixing tank 1.

[0030] The distilled water outlets of the primary evaporator 3 and the vacuum evaporator 5 are connected to the pure water inlet of the feed mixing tank 1 .

[0031] The BPED double decomposition membrane stack 2 adopts a two-compartment configuration of bipolar membrane + female mold to form independent acid chamber and alkali chamber flow channels, and the acid and alkali chamber solutions circulate in their corresponding flow channels respectively. Figure 2 As shown, the BPED double decomposition membrane stack 2 consists of a positive electrode chamber (including an additional adjacent cation exchange membrane d), a negative electrode chamber and a membrane stack basic repeating unit a; wherein the membrane stack basic repeating unit a consists of a bipolar membrane b, an alkali chamber flow channel, an anion exchange membrane c, and an acid chamber flow channel.

[0032] BaSO4 precipitator 4 uses Ba 2+ Ion selective electrodes precisely control the feed ratio.

[0033] Embodiment 2:

[0034] The device described in Example 1 was used to prepare an initial alkali chamber mixed feed solution with high-purity Li2SO4 and glacial acetic acid solid as raw materials and pure water (18.2 MΩ·cm) added. The composition of the initial alkali chamber mixed feed solution was Li2SO4 0.50 mol / L (Li + 1.00 mol / L), HAc 1.02mol / L, Li+ The ratio of HAc concentration is 98%. The BPED double decomposition membrane stack uses the BP-1 bipolar membrane and AMX anionic membrane of Japan's ASTOM company. The BPED operating current density is constant at 500 A / m 2 The initial pH of the alkali chamber is 2.6, which slowly increases during the operation. When it rises to above 5.0, its pH increases rapidly, and the BPED operation is terminated when it reaches 8.0. At this time, the composition of the obtained LiAc crude solution is 0.89 mol / L LiAc, of which the Li2SO4 impurity concentration is 0.075 mol / L. The solution is heated and evaporated at normal pressure, and the evaporator temperature is set to 80°C. The evaporation is stopped when the volume of the residual solution is reduced to 8.1% of the original volume. At this time, a large amount of powdery white solid particles are produced in the solution. After filtering and drying while hot, a pure phase Li2SO4·H2O solid is obtained. The filtrate is the LiAc purified solution, which is composed of LiAc 10.9 mol / L and Li2SO4 0.078 mol / L. While hot, slowly and quantitatively add a 20%wt concentration BaAc2 solution to the solution, using Ba 2+ The ion selective electrode accurately controls the feed ratio, and the battery-grade LiAc solution can be obtained by filtering after standing for about 2 hours. The obtained hot concentrated LiAc solution is dried by vacuum evaporation, and the evaporation temperature is set to 130°C. After visually completely evaporated, the vacuum degree is maintained at -0.09 MPa, and the material is continued to be dried for 3 hours. After cooling to 80°C, the block-shaped battery-grade LiAc solid is obtained, and the finished product is obtained after crushing and sieving. The moisture content of the final anhydrous LiAc solid product is 400 mg / kg, Ba 2+ Content ~45 mg / kg, SO4 2– The content is ~8 mg / kg, which meets battery grade standards.

[0035] Embodiment 3:

[0036] The device described in Example 1 was used, high-purity LiSO4 and glacial acetic acid solid were used as raw materials, and pure water was added to prepare the initial alkali chamber mixed feed solution, the composition of which was Li2SO4 1.50 mol / L (Li + 3.00 mol / L), HAc 2.30 mol / L, Li + The ratio of HAc concentration is 130%. The BPED double decomposition membrane stack uses the BP-1 bipolar membrane and AMX anionic membrane of Japan's ASTOM company. The BPED operating current density is constant at 500 A / m 2The initial pH of the alkali chamber is 2.4, which slowly increases during the operation. When it rises to 6.5, the BPED operation is terminated. At this time, the composition of the obtained LiAc crude solution is 1.90 mol / L LiAc, of which the Li2SO4 impurity concentration is 0.39 mol / L. The solution is heated and evaporated at normal pressure, and the evaporator temperature is set to 110°C. The evaporation is stopped when the residual solution volume is reduced to 20% of the original volume. At this time, a large amount of powdery white solid particles are produced in the solution. After filtering and drying while hot, a pure phase Li2SO4·H2O solid is obtained. The filtrate is the LiAc purified solution, and its composition is LiAc 9.5 mol / L, Li2SO40.085 mol / L. While hot, slowly and quantitatively add a 20%wt concentration BaAc2 solution to the solution, using Ba 2+ The ion selective electrode accurately controls the feed ratio, and the battery-grade LiAc solution can be obtained by filtering after standing for about 2 hours. The obtained hot concentrated LiAc solution is dried by vacuum evaporation, and the evaporation temperature is set to 150°C. After visually completely evaporated, the vacuum degree is maintained at -0.08 MPa, and the material is continued to be dried for 4 hours. After cooling to 80°C, the block-shaped battery-grade LiAc solid is obtained, and the finished product is obtained after crushing and sieving. The moisture content of the final anhydrous LiAc solid product is 300 mg / kg, Ba 2+ Content ~18 mg / kg, SO4 2– Content ~25 mg / kg, meets battery grade standards.

[0037] Example 4

[0038] The device described in Example 1 was used, and the refined LiSO4 solution (~0.60 mol / L) obtained by extracting lithium from ore and solid glacial acetic acid were used as raw materials. An appropriate amount of pure water was added to prepare the initial alkali chamber mixed feed solution, the composition of which was Li2SO4 0.25 mol / L (Li + 0.50 mol / L), HAc 0.56 mol / L, Li + The concentration ratio of HAc is 90%. The BPED double decomposition membrane stack uses the BP-1 bipolar membrane and AMX anionic membrane of Japan's ASTOM company. The BPED operating current density is constant at 500 A / m 2The initial pH of the alkali chamber is 2.7, which slowly increases during the operation. When it rises to 10.0, the BPED operation is terminated. At this time, the composition of the obtained LiAc crude solution is 0.507 mol / L LiAc, of which the Li2SO4 impurity concentration is 0.042 mol / L. The solution is heated and evaporated at normal pressure, and the evaporator temperature is set to 100°C. The evaporation is stopped when the residual solution volume is reduced to 5% of the original volume. At this time, a large amount of powdery white solid particles are produced in the solution. After filtering and drying while hot, a pure phase Li2SO4·H2O solid is obtained. The filtrate is the LiAc purified solution, and its composition is LiAc 10.0 mol / L, Li2SO4 0.080 mol / L. While hot, slowly and quantitatively add 20%wt BaAc2 solution to the solution, using Ba 2+ The ion selective electrode accurately controls the feed ratio, and the battery-grade LiAc solution can be obtained by filtering after standing for about 2 hours. The obtained hot concentrated LiAc solution is dried by vacuum evaporation, and the evaporation temperature is set to 100°C. After visually completely evaporated, the vacuum degree is maintained at -0.095 MPa, and the material is continued to be dried for 8 hours. After cooling to 80°C, the block-shaped battery-grade LiAc solid can be obtained by discharging the material, and the finished product can be obtained after crushing and sieving. The moisture content of the final anhydrous LiAc solid product is 500 mg / kg, Ba 2+ Content ~9 mg / kg, SO4 2– Content ~55 mg / kg, meets battery grade standards.

[0039] Example 5: Typical evolution experiment of LiAc crude solution in primary evaporator 3

[0040] The main component of the crude LiAc solution is LiAc, and it also contains a small amount of Li2SO4 impurities. In the aqueous solution system, both LiAc and Li2SO4 are easily soluble substances. For example, at 80°C, 1000 g of water can dissolve up to 1220 g (18.5 mol) of LiAc and 320 g (2.91 mol) of Li2SO4, respectively. However, experiments have found that in a mixed solution of LiAc and Li2SO4, the presence of LiAc will greatly affect the solubility of Li2SO4. Figure 3 As shown in the figure above, LiAc (Ac – ) and Li2SO4 (SO4 2– ) concentration change diagram, the figure below shows the purity of LiAc in the solution (expressed as [Ac – ] / [SO4 2–]) Change diagram. When a typical LiAc crude solution is evaporated and concentrated at 80°C, in the initial stage (when the LiAc concentration is less than 5 mol / L), LiAc and Li2SO4 are not saturated and precipitated. The concentrations of the two increase linearly with the evaporation of water, and the concentration ratio remains constant; however, when the LiAc concentration increases from 5 mol / L to ~10 mol / L, the Li2SO4 concentration decreases instead of increasing (0.443 – 0.078 mol / L), accompanied by the precipitation of a large amount of white powdery solids, which are pure phase Li2SO4·H2O according to XRD analysis, such as Figure 4 As shown in the figure, when the LiAc concentration in the solution reaches a maximum value (~11 mol / L), its concentration reaches saturation, and the Li2SO4 concentration is also maintained at an extremely low value (~0.078 mol / L). At this time, the solution is almost a pure high-concentration LiAc solution, and its LiAc and Li2SO4 concentration ratio is as high as 140. In this process, most of the Li2SO4 in the crude LiAc solution is separated and recovered in the form of Li2SO4·H2O solid.

Claims

1. A battery-grade lithium acetate production device, comprising a feed mixing tank (1), a BPED double decomposition membrane stack (2), a primary evaporator (3), a BaSO4 precipitator (4) and a vacuum evaporator (5) connected by a pipeline, characterized in that: The feed mixing tank (1) is connected to the alkali chamber inlet of the BPED double decomposition membrane stack (2), the alkali chamber outlet of the BPED double decomposition membrane stack (2) is connected to the liquid inlet of the primary evaporator (3), the crystallized solid outlet of the primary evaporator (3) is connected to the inlet of the feed mixing tank (1), the solution outlet of the primary evaporator (3) is connected to the inlet of the BaSO4 precipitator (4), and the solution outlet of the BaSO4 precipitator (4) is connected to the inlet of the vacuum evaporator (5); The BPED double decomposition membrane stack (2) adopts a two-compartment structure of a bipolar membrane + anion membrane, and is composed of a positive electrode chamber, a negative electrode chamber and a basic repeating unit (a) of the membrane stack, wherein the positive electrode chamber includes an additional adjacent cation exchange membrane (d), wherein the basic repeating unit (a) of the membrane stack is composed of a bipolar membrane (b), an alkali chamber flow channel, an anion exchange membrane (c), and an acid chamber flow channel; Among them, Li2SO4 and acetic acid are used as raw materials.

2. The production device of battery-grade lithium acetate according to claim 1, characterized in that The distilled water outlets of the primary evaporator (3) and the vacuum evaporator (5) are connected to the pure water inlet of the feed mixing tank (1).

3. The production device of battery-grade lithium acetate according to claim 1, characterized in that BaSO4 precipitator (4) uses Ba 2+ Ion selective electrodes precisely control the feed ratio.

4. A method for producing battery-grade lithium acetate using the battery-grade lithium acetate production device according to claim 1, characterized in that The main steps are as follows: (1) Prepare a mixture of Li2SO4 and acetic acid as the initial alkaline chamber solution, where Li + The concentration range is 0.50–3.0 mol / L, Li + The concentration ratio of HAc is 90-130%. Pure water is used as the initial acid chamber solution and is passed into the BPED double decomposition membrane stack (2). The operation is terminated when the pH of the alkaline chamber solution of the BPED double decomposition membrane stack (2) reaches 6-10. Under the action of the DC electric field, a double decomposition reaction of Li2SO4 +2HAc → 2LiAc + H2SO4 occurs, and a LiAc crude solution and a H2SO4 byproduct solution are directly obtained. (2) The crude LiAc solution obtained in step (1) is passed into a primary evaporator (3) at an evaporation temperature of 60-110°C for primary evaporation, concentration and crystallization to obtain Li2SO4·H2O solid and LiAc purified liquid, and the Li2SO4·H2O solid is recycled to prepare the initial alkali chamber solution; (3) passing the purified LiAc solution obtained in step (2) into a BaSO4 precipitator (4), adding a BaAc2 solution, and completely removing the trace amount of residual Li2SO4 impurities in the purified LiAc solution to obtain a battery-grade LiAc solution; (4) The battery-grade LiAc solution obtained in step (3) is passed into a vacuum evaporator (5), the temperature is controlled at 100-150°C, the vacuum degree is ≤0.08 MPa, and vacuum evaporation and drying are performed to obtain battery-grade anhydrous LiAc.

5. The method for producing battery-grade lithium acetate according to claim 4, characterized in that In step (1), when the BPED double decomposition membrane stack (2) is operated, the pH rise of the solution in the alkaline chamber is monitored in real time; the operation termination pH range is 6.5-8.

0.

6. The method for producing battery-grade lithium acetate as claimed in claim 4, characterized in that In step (2), the evaporation temperature in the primary evaporator (3) is 80-100°C.

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