process

Abstract

A method for recovering lithium salts from a lithium battery waste mass, comprising: (a) dissolving the lithium salts in the lithium battery waste mass in a weight of water equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-time process or in a continuous process; (b) evaporating the aqueous solution to dryness; and (c) agitating the dry residue with a solvent comprising water, a carbonate, or a mixture thereof.

Description

[Technical Field]

[0001] The present invention relates to a process for recovering metal salts, particularly lithium salts, contained in electrolytes. [Background technology]

[0002] The need for the effective and sustainable recycling of components from lithium-ion batteries has become more critical than ever, particularly given the anticipated surge in demand for lithium-ion batteries in technologies such as electric vehicles, which are considered one of numerous possible end uses, and the fact that several key components in this technology are in short supply. The use of electrochemical storage systems like lithium-ion batteries is essential to ensure that renewable energy sources can reduce societal dependence on fossil fuels.

[0003] While processes for recycling electrolyte salts exist in prior art, the majority of recycling methods in the context of lithium batteries focus on the recovery and recycling of other battery components such as the positive electrode, negative electrode, casing, and current collector. Lithium, in particular, is the focus of the recovery process, mainly due to its cost. However, many components, such as nickel, copper, and cobalt, retain their value even at the end of the battery's lifespan. Others, such as steel and aluminum, can utilize existing, relatively simple recycling processes. Furthermore, because they tend to constitute a large proportion of the battery's composition, their extraction and purification are relatively economically viable.

[0004] Furthermore, despite the assumption that sufficient demand for lithium has accumulated, there are concerns that the demand for lithium may soon exceed the amount that can be procured from lithium reserves, necessitating the rapid commercialization of innovative solutions.

[0005] The electrolytes and components (salts, additives, and lithium) inside batteries are largely overlooked, and most waste battery processing focuses on removing or destroying these materials at the start of processing. This is largely because they are considered dangerous to work with during long-term recycling processes, and furthermore, their concentrations inside batteries are relatively low. In addition, the compositions of some components, such as lithium hexafluorophosphate (LiPF6), are thought to change during battery aging due to their inherent chemical and thermal instability, rendering attempts at their extraction futile. The degradation of electrolytes is further influenced by the quality of the species within the cell; for example, the presence of proton species impurities has detrimental effects on capacity and cell life.

[0006] However, electrolytes and their components account for approximately 10% by weight of lithium-ion batteries, and therefore, the development of technologies and techniques to enable their recycling is necessary. This is especially true considering that the expected increase in demand for lithium-ion batteries will result in an equivalent increase in waste, and therefore, recycling methods must emerge as needed. Research aimed at extracting electrolytes typically uses supercritical CO2 without solvent addition, but uses only individual discharged battery cells, as opposed to collective sorting of waste materials.

[0007] WO2015 / 193261 (Rhodia Operations) describes a process for recovering metal salts of electrolytes dissolved in a matrix, which consists of subjecting the electrolyte to liquid extraction with water. Preferred salts are certain lithium salts known to be stable in water, such as sulfonimides, perchlorates, and sulfonates. More specifically, the process described herein teaches the isolation of lithium salts from a nonconductive matrix by simply adding water. If the nonconductive matrix for the electrolyte salt contains an organic solvent, the document teaches the use of a water-immiscible organic extraction solvent. This results in the removal of the organic solvent in the nonconductive matrix, which can be retained in the organic phase, and the resulting aqueous and organic phases are immiscible, for example, forming two distinct phases after sedimentation or centrifugation at 25°C and atmospheric pressure.

[0008] US2017 / 0207503 (Commissariat a l'Energie Atomique et aux Energies Alternatives) relates to a method for recycling electrolytes containing a lithium salt of formula LiA, where A is PF6 of a lithium-ion battery. - CF3SO3 - BF4 - , CIO4 - , and [(CF3SO2)2]N -The method represents anion selected from the following, and the method is as follows: a) optionally, the step of processing the battery to recover the electrolyte contained therein; b) the step of adding water to the electrolyte; c) optionally, when step a) is adopted, the step of filtering (F1) to separate the liquid phase containing the electrolyte from the solid phase containing the battery residue; d) the step of adding an additional organic solvent to the liquid phase obtained in step b), or when step a) is adopted, the step of adding an additional organic solvent after filtering (F1) in step c); and e) the step of adding water in step b), or the step of adding an additional organic solvent in step d). The method comprises the steps of: decanting the liquid phase obtained thereafter to obtain an aqueous phase containing a lithium salt and an organic phase containing an electrolyte solvent and an added organic solvent; f) distilling the organic phase obtained in step e) to separate the electrolyte solvent and the added organic solvent; g) precipitation of lithium salt anion A by adding pyridine, followed by filtration (F2); and h) adding at least one carbonate and / or at least one phosphate to the filtrate obtained in step g), followed by filtration (F3), thereby obtaining a lithium salt and water.

[0009] US7820317 (Tedjar) describes a method for processing lithium anode cells, including drying and crushing the cells at room temperature in an inert atmosphere, treatment by magnetic separation and specific gravity table, and water-soluble hydrolysis. [Disclosure of the Invention]

[0010] Against this backdrop, the present invention aims to provide an improved method for recovering and recycling lithium salts from battery electrolyte solutions, particularly a method for recovering LiPF6.

[0011] Further problems have been recognized in the recovery of LiPF6 from used batteries. LiPF6 is a commonly used and commercially important electrolyte salt for lithium batteries, but is recognized as a material that may be susceptible to hydrolysis. Typically, in a typical non-aqueous battery electrolyte solution, LiPF6 exists in an equilibrium state as shown below. [Number]

[0012] Mixing a small amount of water with these LiPF6 solutions will push this equilibrium further to the right as PF5 is hydrolyzed, resulting in additional products such as HF, fluorophosphate, phosphate, and phosphoryl fluoride, POF3. If sufficient water is present, all of the LiPF6 in these solutions will be consumed. The decomposition products of LiPF6 include compounds that are toxic, harmful, and can actually cause further decomposition of other solvents. As a result, the recycling of LiPF6 is considered complex and dangerous.

[0013] According to a first aspect, the present invention provides a method for recovering a lithium salt from a lithium battery waste mass, the method comprising: (a) dissolving the lithium salt in the lithium battery waste mass, either in a single treatment or in a continuous treatment, in water having a weight corresponding to 100 to 0.1 times the weight of the lithium battery waste mass; (b) evaporating and drying the aqueous solution; (c) stirring the dried residue with a solvent containing water, carbonate, or a mixture thereof.

[0014] According to a second aspect, the present invention provides a method for recovering a lithium salt from a lithium battery waste mass, the method comprising: a) dissolving the lithium salt in the lithium battery waste mass, either in a single treatment or in a continuous treatment, in a solvent having a weight corresponding to 100 to 0.1 times the weight of the lithium battery waste mass; b) evaporating and drying the solvent solution; c) stirring the dry residue with a solvent comprising water, an organic solvent, or a mixture thereof.

[0015] Preferably, the final stirring step serves to purify the recovered electrolyte salt.

[0016] In a preferred embodiment, the carbonate solvent is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or a mixture thereof. In one embodiment, the carbonate solvent is ethyl methyl carbonate. Preferably, the stirring step is carried out using a carbonate solvent containing a low level of water such that the carbonate solvent and water are still miscible at 25°C.

[0017] From the perspective of the recovery process, the waste battery cells can be mechanically processed, leaving a fine fraction containing the active electrode and electrolyte materials known as "black mass". Conveniently, the lithium battery waste mass contains the black mass and, preferably, can consist essentially of the black mass. Advantageously, the black mass can constitute at least 80% by weight of the lithium battery waste mass. Black mass is the name given to the powdered material obtained when a spent lithium battery is discharged, disassembled, crushed, shredded, sorted, and sieved. Black mass typically contains many materials including cobalt, nickel, copper, lithium, manganese, aluminum, and graphite. Further metallurgical treatment can be used to enable the extraction of other components, which can include fluorine-containing salts and their decomposition products.

[0018] Black mass is considered to be one of the most useful fractions in battery recycling, due to its concentration of electrode components such as graphite, nickel, manganese, cobalt, lithium, and electrolyte components including conductive salts.

[0019] In one embodiment, the lithium battery waste mass, preferably the black mass, is in a dry state. In this context, "dry" means that the black mass contains less than 20 g / kg of liquid such as the electrolyte solvent and / or water, preferably less than 10 g / kg of liquid, preferably less than 5 g / kg of liquid, preferably less than 1 g / kg of liquid.

[0020] To our surprise, the inventors discovered that lithium hexafluorophosphate, i.e., LiPF6, can be extracted from dried black mass using water without impairing the hydrolysis of the salt or the recovery of electrode components. The solution is then evaporated and dried. The remaining material can then be further purified by working with water or a carbonate solvent. Conveniently, the carbonate solvent can be dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or a mixture thereof, and more conveniently, the carbonate solvent is ethyl methyl carbonate.

[0021] While we do not wish to be bound by theory, despite the dynamic equilibrium with respect to LiPF6 described above, we were surprised to find that the decomposition of LiPF6 in water does not occur as easily as expected. With regard to the initial water dissolution step in the presence of lithium battery waste mass, particularly dried lithium battery waste mass, and particularly dried black mass, this step is preferably carried out under conditions that minimize LiPF6 hydrolysis. Despite the known hydrolytic instability of LiPF6, we found that hydrolysis is minimized either when LiPF6 is substantially dry or when LiPF6 is present in a large amount of relatively stable water.

[0022] When lithium battery waste mass, especially black mass, is washed with water, lithium salts, particularly LiPF6, tend to be present as the most water-soluble salts. Therefore, water-based extraction of black mass has the effect of concentrating and, to some extent, purifying the present lithium salts, especially LiPF6.

[0023] However, the inventors were surprised to find that the expected decomposition of LiPF6 did not occur when the aqueous solution of the LiPF6 salt dried. Similarly, in subsequent steps of the process working with the dried lithium salt using a carbonate solvent or water, LiPF6 was found to be remarkably stable. The inventors' findings suggest that LiPF6 is stable when fully solvated with water, but not when partially solvated. To minimize the harmful decomposition of LiPF6, the detailed steps of the process are selected to minimize the time that LiPF6 is exposed to an amount of water that is not sufficient to completely solvate it. Assuming that prior art teachings require a general multi-step process in which LiPF6 is not recovered, but rather several other lithium salts that need to be resynthesized, the present invention provides a remarkably effective and simple process for recovering and recycling lithium salts, particularly LiPF6, from batteries.

[0024] Surprisingly, given its relative hydrolytic instability, LiPF6 remains present and stable throughout these processes. Ethyl methyl carbonate was shown to be far more selective for dissolving PF6 anions compared to water during the process.

[0025] In one embodiment, the initial dissolution step involves adding water to the lithium ion waste at a relatively low temperature, preferably below 50°C, preferably below 40°C, preferably below 30°C, and preferably below 25°C. The added water is preferably of a purity of more than 95% by weight, more preferably more than 98% by weight, and preferably more than 99% by weight, and preferably contains trace amounts of impurities.

[0026] In one embodiment, the contact time of water with the lithium battery waste manhole may be 10 hours or less, preferably 5 hours or less, preferably 2 hours or less, and in some embodiments, the contact time may be 1 hour or 30 minutes or less. In other embodiments, the contact time may be less than 10 minutes, conveniently less than 5 minutes, conveniently less than 2 minutes, conveniently less than 1 minute.

[0027] In the step of evaporation and drying, it is preferable that the temperature of the solution to be dried not rise above the preferred temperature described above for the dissolution step. For this purpose, vacuum filtration or spray drying are preferred methods for evaporating and drying the aqueous solution, and in certain embodiments, spray drying may be preferred.

[0028] In one embodiment, in step (a), water is drawn out under vacuum through a lithium battery waste mass (e.g., a black mass). In a further embodiment, in step (a), water passes dynamically through the lithium battery waste mass (i.e., not through in a batch process).

[0029] In one embodiment, the weight ratio of water to lithium battery waste (e.g., black mass) in the extraction step is within the range of 100 to 0.1:1, conveniently 10 to 0.5:1, conveniently 7 to 0.5:1, conveniently 5 to 0.5:1, and conveniently 3 to 0.5:1. [Examples]

[0030] Example 1 - Water-soluble extraction procedure We provided recyclable battery mass powder (commonly called black mass) for use, generated from the processing of spent batteries having NMC622 positive electrodes and graphite negative electrodes. Since this material was estimated to contain at most approximately 2 wt% LiPF6, this figure was used as a reference when calculating yields, etc. LiPF6 is understood to be soluble in water and, despite its high instability to hydrolysis, is stable when fully solvated with water, but unstable until fully solvated with water. Initial studies aimed to identify any variability between experimental parameters, including extraction / mixing time and the volume of water used. The results are shown in Table 1.

[0031] The mass of black muss (5g), mixing rate, and room temperature were kept constant. In each experiment, the extract was... 19 F and 31 LiPF6 was obtained as confirmed by 1P NMR analysis. While the extraction time did not appear to be significant in determining how much LiPF6 and other species were extracted, the volume of water used had a major impact. In particular, reducing the amount of water used for extraction led to improved LiPF6 recovery. [Table 1]

[0032] Next, the effect of sample heterogeneity in black mass on the yield was reduced by using a water volume and battery material mass that were four times larger. In this experiment, 20 g of black mass was extracted with 80 ml of water for 3 hours, resulting in a LiPF6 recovery rate of 78.5%, which was similar to comparable small-scale experiments.

[0033] In further experiments, 20 mL of water was passed through a bed of 5 g of black mass in a column held in place by filter paper, resulting in a LiPF6 recovery rate of 89.1% and a significant decrease in fluoride levels. Any PF6 anions present in the black mass can be assumed to undergo hydrolysis when sufficient time and water are provided. Therefore, the key to recovering it in good yield is to optimize the amount of water, contact time, and contact mode, such as batch mode or dynamic mode, with respect to the black mass. However, the extraction step was found to be operable over a wide range of these parameters and still effective.

[0034] Figures 1 and 2 are typical of water-soluble extracts useful for confirming the presence of PF6 anions in the water-soluble extract solution 19 F and 31 show P NMR spectra.

[0035] Example 2 - LiPF from Black Mass 6 Extraction and recovery Water-soluble extraction of black mass powder The soluble components from a sample of the black mass (5 g) material were extracted with water (10 mL) using batch contact in an open beaker with mixing for a specified period (1.5 h). After this specified period, the resulting orange mixture was filtered under vacuum to obtain an orange filtrate made up of 10 mL of water. This solution was 19 analyzed by F and 31 P NMR to confirm the presence of PF6 anions and determine its concentration, and thus the recovery rate. The doublet was 19 observed by F NMR and the septet was 31 observed by P NMR, and the amount of LiPF6 in the solution was 19 determined by F NMR to correspond to 10.97 mg / g of black mass.

[0036] Removal of solvent from filtrate A portion of the filtrate was transferred to a 75 mL round-bottom flask, and water was removed under vacuum at 30 mbar and 45°C. Under these conditions, all solvent was removed in less than 30 minutes.

[0037] The solid residue obtained after removing the water is redissolved in water (10 mL), and the solution thus obtained is 19 F and 31 Further analysis by 1P NMR showed that the PF6 anion survived most of the water removal and redissolution steps intact. 19 By 1F NMR, the LiPF6 content of this solution was determined to be 10.80 mg / g of black mass, which is a slight decrease from the 10.97 mg / g of black mass in the original extract.

[0038] Selective extraction of LiPF6 from solid residue to ethyl methyl carbonate (EMC). The extraction and evaporation steps described above were repeated, and the resulting solid residue was extracted using EMC. The resulting water-soluble extract and EMC solution were then... 31 Analysis by 1P NMR spectroscopy showed that the PF6 anion survived the extraction and evaporation processes intact and was extracted from the evaporation residue by EMC; see Figure 3.

[0039] PF in EMC solvent 6 Stability of anions The PF6 ion sample recovered by extraction to EMC was stored for 15 days. 19 The concentration of PF6 anions in the solution over this period was quantified using 1F NMR. The results are shown in Table 2 below, demonstrating that PF6 anions are stable in EMC after water removal and extraction in EMC for at least two weeks. [Table 2]

[0040] Example 3: Repeated demonstration of process steps The basic water-soluble extraction of the solid, solvent removal, and extraction procedure of Example 2 were repeated six times, and the results are summarized in Table 3. The amount of LiPF6 extracted and recovered in the EMC solution was... 19 Quantification by 1F NMR, 31 Confirmed by 1P NMR. [Table 3]

[0041] Example 4: Repeating the washing / processing step The basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 were repeated five times on the same sample, and the results are summarized in Figure 4. The amount of LiPF6 extracted and recovered was: 19 Quantification by 1F NMR, 31 Confirmed by 1P NMR.

[0042] Example 5: LiPF from Black Mass 6 Extraction and recovery The basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 were repeated on three different battery material samples (200 g) using 100 mL of solvent, and the results are summarized in Table 4. The amount of LiPF6 extracted and recovered was: 19 Quantification by 1F NMR, 31 Confirmed by 1P NMR. [Table 4]

[0043] Example 6: LiPF from black mass 6 Extraction and recovery Solvent extraction with water or EMC The basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 were repeated on three different battery material samples (200 g) with 100 mL of solvent, and the results are summarized in Figures 5 to 7. Both layers were analyzed by ion chromatography (upper layer - anions, lower layer - cations). The blue profile represents the separated water-soluble composition, and the pink profile represents the composition of the remaining EMC mixture. The amount of LiPF6 extracted and recovered was...19 Quantification by 1F NMR, 31 Confirmed by 1P NMR.

[0044] The black profile is extracted directly from the battery material with water. It can be clearly seen that the majority of PF6-, along with Li+ and some Na+, migrate to the aqueous phase, leaving some residual ions in the EMC.

[0045] Further extraction of EMC extract An EMC mixture containing LiPF6 was washed with an equal volume of water, and ether was added to facilitate the separation of the organic and aqueous layers. Both layers, analyzed by ion chromatography (top - anions, bottom - cations), and their results are summarized in Figures 8-10. The blue profile represents the separated water-soluble composition, the pink profile represents the composition of the remaining EMC mixture, and the black profile represents the direct extraction from the battery material with water. PF6 - Most of them are Li + and some Na + Furthermore, it can be clearly understood that some residual ions are left in the EMC and move to the aqueous phase.

[0046] Example 7: LiPF from black mass 6 Extraction and recovery Solvent extraction with water or EMC The basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 were repeated on different battery material samples (200 g) using 100 mL of solvent (DMC or water), and the results are summarized in Figure 11 (DMC (blue), water (black)). The amount of LiPF6 extracted and recovered was: 19 Quantification by 1F NMR, 31 Confirmed by 1P NMR.

[0047] It can be understood that extracting LiPF6 using organic carbonates does not necessarily extract all other components that would be observed when water is used. The majority of the material extracted by DMC is LiPF6.

[0048] Example 8: LiPF from Black Mass 6 Extraction and recovery Solvent extraction with water The basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 were repeated on four different battery material samples (200 g) using 100 mL of solvent (water), and the results are summarized in Figure 12 (DMC (blue), water (black)). The amount of LiPF6 extracted and recovered was: 19 Quantification by 1F NMR, 31 Confirmed by 1P NMR.

[0049] It can be understood that the different samples show different amounts of LiPF6 and the degree of hydrolysis of the existing LiPF6. The figure shows the anion chromatogram.

[0050] Example 9: LiPF using different solvents 6 Measurement, extraction, and recovery Solvent extraction Solid water-soluble extraction, solvent removal, and extraction were performed.

[0051] Table 5 below shows the measured values ​​of extracted LiPF6 based on either PF6 anions or Li cations (by ion chromatography) in various solvents, using different solvents. [Table 5]

[0052] Assuming that the concentration of LiPF6 is based on both the amount of PF6 and the amount of Li, it has been shown that when water is used as the extraction solvent compared to EMC, there is a significant excess of Li.

[0053] These results are illustrated in Figures 13a and 13b.

[0054] It can be seen that there are clear differences in the additional components extracted from black mass samples when water is used compared to when EMC is used. The anion chromatogram shown above (the colors are not the same as those of the WBM batch) is shown above.

[0055] Example 10: 200 g of waste battery material was washed with 100 mL of EMC. The filtrate was divided into three portions: untreated material, one 7 g portion sieved through a 4 angstrom molecular sieve, and another 7 g portion in the form of MgO pellets. Both portions were left in a ventilated chamber for one week, and their moisture content was analyzed using a Coulomycal Karl Fischer analyzer, followed by decomposition using an IC. The results are shown in Table 6 below. [Table 6]

[0056] This highlights the importance of immediately drying the solvent, as LiPF6 extracts a large amount of water, which hydrolyzes into known degradation products. [Various forms] This disclosure encompasses the following aspects: [Aspect 1] A method for recovering lithium salts from lithium battery waste masses, (a) Dissolving the lithium salt in the lithium battery waste mass in water equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-time treatment or a continuous treatment; (b) The step of evaporating the aqueous solution and drying it, (c) A method comprising the step of stirring the dried residue with a solvent containing water, an organic solvent, or a mixture thereof. [Aspect 2] A method for recovering lithium salts from lithium battery waste masses, b) Dissolving the lithium salt in the lithium battery waste mass in a solvent equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-time treatment or a continuous treatment; d) A step of evaporating the solvent solution and drying it, e) A method comprising the step of stirring a dried residue with a solvent containing water, an organic solvent, or a mixture thereof. [Aspect 3] The method according to embodiment 2, wherein the solvent in step (a) includes an ether solvent (such as diethyl ether), a nitrile solvent (such as acetonitrile or propionitrile), a carboxylate solvent (such as ethyl acetate), or a carbonate solvent (such as propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or any mixture thereof) that does not contain water or contains a low level of water such that the water and the solvent are still miscible at 25°C. [Aspect 4] The method according to embodiment 1, 2, or 3, wherein the solvent in step (c) includes an ether solvent (such as diethyl ether), a nitrile solvent (such as acetonitrile or propionitrile), a carboxylate solvent (such as ethyl acetate), or a carbonate solvent (such as propylene carbonate, dimethyl carbonate, diethyl carbonate, or ethyl methyl carbonate) that does not contain water or contains a low level of water such that the water and the solvent are still miscible at 25°C. [Aspect 5] The method according to any one of embodiments 1 to 4, wherein the final stirring step (c) helps to purify the recovered electrolyte salt. [Aspect 6] The method according to any one of embodiments 1 to 5, wherein the carbonate solvent is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, or a mixture thereof. [Aspect 7] The method according to embodiment 5, wherein the solvent used in the stirring step (c) contains no water or contains a low level of water such that the water and the carbonate solvent are still miscible at 25°C. [Aspect 8] The method according to any one of the prior art, wherein the lithium battery waste mass includes a black mass. [Aspect 9] The method according to embodiment 8, wherein the black mass constitutes at least 80% by weight of the lithium battery waste mass. [Aspect 10] The method according to any one of the prior embodiments, wherein the lithium battery waste mass prior to step (a) is dry and, conveniently, contains less than 20 g / kg of liquid. [Aspect 11] The lithium salt is LiPF 6 The method according to any one of the prior embodiments. [Aspect 12] The method according to any one of the prior art, wherein the dissolution step (a) is carried out at a temperature below 50°C. [Aspect 13] The method according to any one of the prior embodiments, wherein the dissolution step (a) is carried out using water having a purity of more than 95% by weight. [Aspect 14] The method according to any one of the prior art, wherein the contact time of the water with the lithium-ion battery mass in step (a) is less than 5 hours, and preferably less than 10 minutes. [Aspect 15] The method according to any one of the prior embodiments, wherein step (b) of evaporating and drying is performed by vacuum evaporation or spray drying. [Aspect 16] The method according to any one of the prior embodiments, wherein the dissolution step (a) is performed dynamically. [Aspect 17] The method according to any one of the prior art, wherein the weight ratio of water to lithium battery waste mass is 10 to 0.5:1, and conveniently 3 to 0.5:1. [Brief explanation of the drawing]

[0057] [Figure 1] Typical 19F and 31P NMR spectra of the water-soluble extract are shown, which help confirm the presence of PF6 anions in the water-soluble extract solution in Example 1. [Figure 2] Typical 19F and 31P NMR spectra of the water-soluble extract are shown, which help confirm the presence of PF6 anions in the water-soluble extract solution in Example 1. [Figure 3] The 31P NMR spectra of the water-soluble extract and EMC solution in Example 2 are shown. [Figure 4]The results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 five times on the same sample are shown. [Figure 5] The results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 on three different battery material samples (200 g) using 100 mL of solvent are shown. [Figure 6] The results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 on three different battery material samples (200 g) using 100 mL of solvent are shown. [Figure 7] The results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 on three different battery material samples (200 g) using 100 mL of solvent are shown. [Figure 8] The layers analyzed by ion chromatography (upper layer - anions, lower layer - cations) in Example 6, and their results are shown. [Figure 9] The layers analyzed by ion chromatography (upper layer - anions, lower layer - cations) in Example 6, and their results are shown. [Figure 10] The layers analyzed by ion chromatography (upper layer - anions, lower layer - cations) in Example 6, and their results are shown. [Figure 11] The results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid in Example 2 on different battery material samples (200 g) using 100 mL of solvent (DMC or water) are shown. [Figure 12] In Example 8, the results of repeating the basic water-soluble extraction, solvent removal, and extraction of the solid from Example 2 on four different battery material samples (200 g) using 100 mL of solvent (water) are shown. [Figure 13A] The results of Example 9 are shown graphically. [Figure 13B] The results of Example 9 are shown graphically.

Claims

1. A method for recovering lithium salts from lithium battery waste masses, (a) Dissolving the lithium salt in the lithium battery waste bin in water equivalent to 100 to 0.1 times the weight of the lithium battery waste bin, either in a one-time treatment or a continuous treatment; (b) A step of evaporating the aqueous solution and drying it, (c) A method comprising the step of stirring the dried residue with a solvent comprising water, an organic solvent, or a mixture thereof.

2. A method for recovering lithium salts from lithium battery waste masses, (a) Dissolving the lithium salt in the lithium battery waste mass in a solvent equivalent to 100 to 0.1 times the weight of the lithium battery waste mass, either in a one-time treatment or a continuous treatment; (b) The step of evaporating the solvent solution and drying it, (c) A method comprising the step of stirring the dried residue with a solvent comprising water, an organic solvent, or a mixture thereof.

3. The method according to claim 2, wherein the solvent in step (a) is an ether solvent, a nitrile solvent, a carboxylate solvent, or a carbonate solvent that does not contain water, or contains water and a low level of water such that the solvent is still miscible at 25°C.

4. (i) The ether solvent comprises diethyl ether, and / or (ii) The nitrile solvent includes acetonitrile or propionitrile, and / or (iii) The carboxylate solvent contains ethyl acetate, and / or (iv) The method according to claim 3, wherein the carbonate solvent comprises propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or any mixture thereof.

5. The method according to any one of claims 1 to 4, wherein the solvent in step (c) is an ether solvent, a nitrile solvent, a carboxylate solvent, or a carbonate solvent that does not contain water, or contains water and a low level of water such that the solvent is still miscible at 25°C.

6. (i) The ether solvent comprises diethyl ether, and / or (ii) The nitrile solvent includes acetonitrile or propionitrile, and / or (iii) The carboxylate solvent contains ethyl acetate, and / or (iv) The method according to claim 5, wherein the carbonate solvent comprises propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or any mixture thereof.

7. The method according to any one of claims 1 to 4, wherein the final stirring step (c) helps to purify the recovered electrolyte salt.

8. The method according to claim 3 or 4, wherein the carbonate solvent is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, or a mixture thereof.

9. The method according to claim 7, wherein the solvent used in the stirring step (c) comprises a carbonate solvent that does not contain water or contains a low level of water such that the water and carbonate solvent are still miscible at 25°C.

10. The method according to any one of claims 1 to 4, wherein the lithium battery waste mass includes black mass.

11. The method according to claim 10, wherein the black mass constitutes at least 80% by weight of the lithium battery waste mass.

12. The method according to any one of claims 1 to 4, wherein the lithium battery waste mass prior to step (a) is dry and, conveniently, contains less than 20 g / kg of liquid.

13. The lithium salt is LiPF ６ The method according to any one of claims 1 to 4.

14. The method according to any one of claims 1 to 4, wherein the dissolution step (a) is carried out at a temperature of less than 50°C.

15. The method according to any one of claims 1 to 4, wherein the dissolution step (a) is carried out using water having a purity of more than 95% by weight.

16. The method according to claim 1, wherein the contact time of the water with the lithium battery waste basin in step (a) is less than 5 hours, and preferably less than 10 minutes.

17. The method according to any one of claims 1 to 4, wherein the step of evaporating and drying (b) is carried out by vacuum evaporation or spray drying.

18. The method according to any one of claims 1 to 4, wherein the dissolution step (a) is performed dynamically.

19. The method according to claim 1, wherein the weight ratio of water to lithium battery waste mass is 10 to 0.5:1, and preferably 3 to 0.5:1.

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