Recycling method and apparatus for polyvalent anion lithium secondary battery cathode material

Abstract

To provide a method and apparatus for recycling a polyanion-based lithium positive electrode material for a lithium secondary battery, which does not generate toxic by-products such as acid waste and simply and efficiently separates a high-value substance from the positive electrode material for the secondary battery.SOLUTION: A method for recycling a polyanion-based lithium secondary battery positive electrode material includes a step S100 of chlorinating a polyanion-based lithium secondary battery positive electrode material separated from a battery with a chlorine-containing gas to form a first mixture containing a compound containing a polyanion and lithium chloride (LiCl), and a step S200 of contacting the first mixture with a solvent to separate and obtain a second mixture containing the compound containing a polyanion, lithium chloride, and the solvent.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for recycling a polyvalent anion-based lithium secondary battery cathode material for a lithium secondary battery. More specifically, the present invention relates to a method and an apparatus for recycling a polyvalent anion-based lithium secondary battery cathode material that do not generate toxic by-products such as acid waste and can simply and efficiently separate high-value substances of the secondary battery cathode material.

Background Art

[0002] As the technology development and demand for mobile devices, electric vehicles, and hybrid vehicles increase, the demand for secondary batteries as an energy source has increased rapidly.Concerning such secondary batteries, lithium secondary batteries that exhibit high energy density, operating potential, long cycle life, and low self-discharge rate have been commercialized and widely used.

[0003] Recently, as the interest in environmental issues has grown, there has been a lot of research on electric vehicles (EVs) and hybrid electric vehicles (HEVs) that can replace vehicles using fossil fuels such as gasoline vehicles and diesel vehicles, which are one of the main causes of air pollution. As power sources for such electric vehicles (EVs) and hybrid electric vehicles (HEVs), nickel-metal hydride (Ni-MH) secondary batteries are mainly used. Currently, research on using lithium secondary batteries with high energy density, high discharge voltage, and output stability is actively underway, and some have been commercialized.

[0004] A lithium secondary battery has a structure in which a non-aqueous electrolyte containing a lithium salt is impregnated into an electrode assembly in which a porous separator is interposed between a positive electrode and a negative electrode, on which active materials are respectively coated on a current collector. As such a positive electrode active material of a lithium secondary battery, lithium cobalt-based oxides, lithium manganese-based oxides, lithium nickel-based oxides, lithium composite oxides, etc. are used, and as a negative electrode active material, carbon materials are mainly used, and the use of silicon compounds, sulfur compounds, etc. is also considered.

[0005] When manufacturing automotive batteries that require high output characteristics, the need for cathode materials that can assist output at low voltage ranges has emerged. Recently, lithium iron phosphate secondary batteries (LiFePO4 secondary batteries) using lithium iron phosphate (LiFePO4), the active material of polyvalent anion lithium cathode materials, have been proposed.

[0006] LFP batteries (LiFePO4 batteries) have a lower operating voltage range compared to conventional positive electrode active materials such as ternary systems (Li(Ni,Mn,Co)O2) and spinel manganese (LiMn2O4), but they have the advantage of stable operation, and their application areas are expanding more and more in light of the current situation where safety issues are becoming increasingly prominent. As interest in lithium-ion batteries increases and their applications expand, so does interest in recycling the high-value materials contained within them. To date, lithium-ion battery recycling processes have focused solely on recovering lithium, nickel, and manganese-cobalt contained in ternary systems (Li(Ni,Mn,Co)O2) and spinel manganese (LiMn2O4), and recycling of LFPs (lithium-fructose phosphates) has not yet received much attention.

[0007] However, post-consumption of LFP batteries in particular can mitigate the lifecycle impact of electric vehicles by almost 50%. The global warming potential associated with LFP production per kilogram, calculated using lifecycle analysis, is approximately 19-55 MJ. Therefore, recycling all lithium-ion batteries, not just those rich in nickel, cobalt, and manganese, would present a good opportunity to revitalize local economies by applying long-term circular economy principles.

[0008] Furthermore, in the case of conventionally known recycling methods for NCM-based cathode materials, when applying these methods to polyvalent anion-based cathode materials, there was a problem in that the application was either impossible or the recycling efficiency was drastically reduced due to the difference in crystal structure between NCM-based cathode materials and polyvalent anion-based cathode materials. As a result, a process for recycling LFPs has been proposed (International Public Publication WO2023 / 050014), but this has problems: the recycling process is too complex, making it unfavorable from an economic and practical standpoint, and the use of toxic, highly acidic substances in the recycling process makes it extremely unfavorable from an environmental standpoint.

[0009] Therefore, there is an urgent need for research on a recycling method for polyvalent anionic lithium secondary battery cathode materials that can be applied to polyvalent anionic lithium cathode materials including LFP, does not use toxic acidic substances in the process, is advantageous from the viewpoint of safety and environmental compatibility, and enables selective separation and recovery of cathode material materials in a simple and efficient process. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] International Public Gazette WO2023 / 050014 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention was devised to solve the above-mentioned problems, and aims to provide a recycling method and apparatus for polyvalent anionic lithium secondary battery cathode materials that can safely separate lithium and polyvalent anionic compounds contained in the polyvalent anionic lithium secondary battery cathode material contained in waste batteries, ultimately reducing the social and economic costs of lithium secondary batteries.

[0012] In addition, in the recycling process, by not using toxic acidic chemical substances, it is excellent from the viewpoints of safety and environmental compatibility, does not require further purification steps, and there is another object of providing a recycling method and apparatus for a lithium positive electrode material that are excellent from the viewpoints of economy and utilization degree.

Means for Solving the Problems

[0013] In order to solve the above-described problems, the present invention reacting a polyvalent anion-based lithium secondary battery positive electrode material separated from a battery with a chlorine-containing gas to form a first mixture containing a compound containing a polyvalent anion and lithium chloride (LiCl); and (2) separating and obtaining a second mixture containing a compound containing a polyvalent anion, lithium chloride, and a solvent by bringing the first mixture into contact with a solvent. A recycling method for a polyvalent anion-based lithium secondary battery positive electrode material is provided.

[0014] After the step (2), a step of removing the solvent from the second mixture to obtain lithium chloride may further be included.

[0015] The polyvalent anion-based lithium secondary battery positive electrode material in the step (1) may be LiA x (PO4) y and may be.

[0016] Here, A is any one or more selected from the group consisting of iron (Fe), cobalt (Co), manganese (Mn), and nickel (Ni), and x and y satisfy 0.5 < x ≤ 3.0 and 0.5 < y ≤ 3.0.

[0017] The chlorination reaction temperature may be 20 to 280°C.

[0018] The chlorination reaction temperature may be 170 to 280°C.

[0019] Further, the gas containing chlorine may contain any one or more selected from the group consisting of chlorine gas (Cl2), hydrogen chloride (HCl), phosgene (COCl2), and carbon tetrachloride (CCl4).

[0020] Further, the solvent may contain any one or more selected from the group consisting of water, ethanol, methanol, butanol, propanol, hydrazine, methyl formaldehyde, acetone, formic acid, pyridine, and benzene.

[0021] Further, the present invention provides a method for recycling a polyvalent anion-based lithium secondary battery positive electrode material, comprising: (1) a step of subjecting a polyvalent anion-based lithium secondary battery positive electrode material separated from a battery to a chlorination reaction with a gas containing chlorine to form a first mixture containing a compound containing a polyvalent anion and lithium chloride (LiCl); (2) a step of contacting the first mixture with a solvent to separately obtain a second mixture containing a compound containing a polyvalent anion, lithium chloride, and the solvent; (3) a step of reacting the second mixture with a carbonate to form a third mixture containing lithium carbonate (Li2CO3); and (4) a step of separating lithium carbonate from the third mixture.

[0022] Further, the present invention provides a method for recycling a polyvalent anion-based lithium secondary battery positive electrode material, comprising: (1) a step of subjecting a polyvalent anion-based lithium secondary battery positive electrode material separated from a battery to a chlorination reaction with a gas containing chlorine to form a first mixture containing a compound containing a polyvalent anion and lithium chloride (LiCl); (2) a step of contacting the first mixture with a solvent to separately obtain a second mixture containing a compound containing a polyvalent anion, lithium chloride, and the solvent; (3) a step of reacting the second mixture with a carbonate to form a third mixture containing lithium carbonate (Li2CO3); (4) a step of separating lithium carbonate from the third mixture; (5) a step of reacting the lithium carbonate with calcium hydroxide to obtain a fourth mixture containing lithium hydroxide (LiOH) and calcium carbonate (CaCO3); and (6) a step of separating lithium hydroxide from the fourth mixture.

[0023] Also, after the above (2) steps, a step (7) of introducing a lithium compound into the compound containing the polyvalent anion to form a fifth mixture; a step (8) of reacting the fifth mixture to reform the phase of the polyvalent anion-based lithium secondary battery positive electrode material; and a step (9) of improving the crystallinity of the fifth mixture and resynthesizing it into a polyvalent anion-based lithium secondary battery positive electrode material excellent in electrochemical activity; may be further included.

[0024] Also, the lithium compound may be lithium carbonate separated from the third mixture in the above (4) step or lithium hydroxide (LiOH) separated from the fourth mixture in the above (6) step.

[0025] Also, the number of moles of lithium ions in the lithium compound may be 100 to 120% of the number of moles of metal ions in the compound containing the polyvalent anion.

[0026] Also, the above (8) step may be to react the fifth mixture at a temperature of 200 to 400 °C for 1 to 24 hours.

[0027] Also, the above (9) step may be to react the fifth mixture at a temperature of 500 to 850 °C for 1 to 24 hours.

[0028] Also, the resynthesized polyvalent anion-based lithium secondary battery positive electrode material may have an initial discharge capacity of 100 mAh / g or more.

[0029] Also, the present invention provides a recycling device for a polyvalent anion-based lithium secondary battery positive electrode material, including a first reaction part that chlorinates the polyvalent anion-based lithium secondary battery positive electrode material separated from a battery with a chlorine-containing gas to form a first mixture containing a compound containing a polyvalent anion and lithium chloride; and a first separation part that communicates with the first reaction part and separates and obtains a second mixture containing a compound containing a polyvalent anion, lithium chloride, and a solvent by bringing the first mixture into contact with the solvent.

[0030] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a second reaction unit communicating with a first separation unit and reacting the second mixture with a carbonate to form a third mixture containing lithium carbonate; and a second separation unit communicating with the second reaction unit and separating lithium carbonate from the third mixture.

[0031] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a third reaction unit communicating with a second separation unit and reacting the lithium carbonate with calcium hydroxide to form a fourth mixture containing lithium hydroxide (LiOH) and calcium carbonate (CaCO3); and a third separation unit communicating with the third reaction unit and separating lithium hydroxide from the fourth mixture.

[0032] Furthermore, the recycling apparatus for polyvalent anion-based lithium secondary battery cathode material according to the present invention may further include a synthesis unit that communicates with the first separation unit, the second separation unit, and the third separation unit, and resynthesizes the polyvalent anion-based lithium secondary battery cathode material from the compound containing polyvalent anions, lithium carbonate, and lithium hydroxide separated in the first separation unit, the second separation unit, and the third separation unit.

[0033] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a gas injection unit for injecting gas into the first reaction unit. [Effects of the Invention]

[0034] The present invention provides a method and apparatus for recycling polyvalent anionic lithium cathode materials that can safely separate lithium and polyvalent anionic compounds contained in polyvalent anionic lithium cathode materials contained in waste batteries, ultimately reducing the social and economic costs of lithium secondary batteries.

[0035] Furthermore, because this recycling process does not use toxic acidic chemicals, it is superior in terms of safety and environmental compatibility, and because it does not require further purification processes, it is also excellent in terms of economic efficiency and usability. [Brief explanation of the drawing]

[0036] [Figure 1] Figure 1 is a flowchart illustrating a schematic method for recycling a polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention. [Figure 2] Figure 2 is a flowchart illustrating a method for recycling the cathode material of a secondary battery according to another embodiment of the present invention. [Figure 3] Figure 3 is a flowchart illustrating a method for recycling secondary battery cathode material according to yet another embodiment of the present invention. [Figure 4] Figure 4 is a flowchart illustrating a method for recycling secondary battery cathode material according to yet another embodiment of the present invention. [Figure 5] Figure 5 shows a recycling device for polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention. [Figure 6] Figure 6 shows a recycling apparatus for polyvalent anion lithium secondary battery cathode material according to another embodiment of the present invention. [Figure 7] Figure 7 shows a recycling apparatus for polyvalent anion lithium secondary battery cathode material according to yet another embodiment of the present invention. [Figure 8] Figure 8 shows a recycling apparatus for polyvalent anion lithium secondary battery cathode material according to yet another embodiment of the present invention. [Figure 9] Figure 9 is a graph showing the results of X-ray diffraction experiments on all products after chlorinating LFP according to one embodiment of the present invention. [Figure 10] Figure 10 is a graph showing the results of an X-ray diffraction experiment on the solid material remaining after separating the product through water following a chlorination reaction of LFP according to one embodiment of the present invention. [Figure 11] Figure 11 is a photograph showing the recycling process of an electrode containing a polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention. [Figure 12] Figure 12 is a graph showing the results of an X-ray diffraction experiment on solid products obtained by separating an electrode containing a polyvalent anion lithium secondary battery cathode material from a chlorination reaction with water, according to one embodiment of the present invention. [Figure 13] Figure 13 is a graph showing the results of an X-ray diffraction experiment on the resynthesis product of a polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention, compared with the results of an experiment on a cathode material product resynthesized without using the method of the present invention. [Figure 14] Figure 14 is a graph showing the analysis results for the discharge capacity of the resynthesis product of a polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention, compared with the analysis results for a cathode material product resynthesized without using the method of the present invention. [Figure 15] Figure 15 is a graph showing the results of X-ray diffraction experiments on the resynthesis product of a polyvalent anion lithium secondary battery cathode material according to yet another embodiment of the present invention, compared with the results of experiments on a cathode material product resynthesized without the method of the present invention. [Modes for carrying out the invention]

[0037] The embodiments of the present invention will be described in detail below so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. The present invention can be embodied in a variety of different forms and is not limited to the embodiments described herein.

[0038] As mentioned above, conventional secondary battery cathode material recycling methods are either not applicable to polyvalent anionic lithium cathode materials such as LFP, or, even if applicable, they have limitations such as using toxic acidic substances in the process, making them unfavorable from the standpoint of safety and environmental compatibility, or requiring further purification processes, making them unfavorable from the standpoint of economics and usability.

[0039] Therefore, the present invention provides a method for recycling polyvalent anion lithium secondary battery cathode material, comprising the steps of (1) reacting polyvalent anion lithium secondary battery cathode material with a chlorine-containing gas to form a first mixture containing a polyvalent anion compound and lithium chloride, and (2) contacting the first mixture with a solvent to separate and obtain a second mixture containing the polyvalent anion compound, lithium chloride and the solvent, thereby seeking to solve the aforementioned problems. This aims to safely separate lithium and polyvalent anion compounds contained in polyvalent anion lithium cathode material contained in waste batteries, ultimately reducing the social and economic costs of lithium secondary batteries. Furthermore, by not using toxic acidic chemicals in the recycling process, this method is safer and more environmentally friendly than conventional recycling methods, does not require further purification steps, and allows for easy and efficient separation of high-value substances, providing an economically superior recycling method for polyvalent anion lithium secondary battery cathode material.

[0040] Figure 1 is a flowchart illustrating a method for recycling a polyvalent anion lithium secondary battery cathode material according to one embodiment of the present invention. The present invention will be described in detail below with reference to this figure.

[0041] First, in step (1), the polyvalent anion lithium secondary battery cathode material separated from the battery is subjected to a chlorination reaction with a chlorine-containing gas to form a first mixture containing a polyvalent anion compound and lithium chloride (S100 in Figure 1).

[0042] In conventionally known recycling methods for NCM-based cathode materials, applying these methods to polyvalent anion-based cathode materials presented problems due to differences in chemical properties and crystal structures between NCM-based and polyvalent anion-based cathode materials. These problems included either the method being impossible to apply or resulting in a significant reduction in recycling efficiency.

[0043] Therefore, a recycling method has been reported for polyvalent anionic lithium secondary battery cathode materials, in which waste batteries are leached in a strong acid solution to separate lithium, cathode material metal, and polyvalent anionic material. However, such separation methods using strong acids have problems other than generating further acid waste. For example, lithium is separated together with other metals during the separation process due to its reactivity, requiring further purification steps to separate lithium, and the separation efficiency is significantly reduced due to the similar chemical properties of the metals.

[0044] Therefore, the present invention solves the aforementioned problems by subjecting a polyvalent anion lithium secondary battery cathode material to a chlorine reaction with a chlorine-containing gas. More specifically, waste batteries may contain polyvalent anion lithium compounds, which are secondary battery cathode material materials. In the present invention, the chlorine reaction carried out in step (1) can separate these compounds into a compound containing lithium and polyvalent anions. That is, lithium is converted into lithium chloride and can be separated from the compound containing polyvalent anions.

[0045] As a result, the present invention can simplify the overall process through the selective and easy recovery of lithium chloride, without generating secondary acid waste, thereby maximizing processing efficiency and process efficiency.

[0046] Specifically, the compound containing the polyvalent anion may be a compound remaining after lithium has been removed from the compound of chemical formula 1 contained in the polyvalent anion lithium secondary battery cathode material described later. For example, if the compound of chemical formula 1 is LiFePO4, the compound containing the polyvalent anion may be FePO4.

[0047] In addition, the compound containing a polyvalent anion may be alone or may further contain some impurities or solvents usually contained therein.

[0048] Here, the polyvalent anion-based compound can be recycled in a manner of being resynthesized into the positive electrode material of the secondary battery through the steps described below.

[0049] Specifically, the polyvalent anion-based lithium secondary battery positive electrode material separated from the battery may contain a compound of Chemical Formula 1 below. <Chemical Formula 1>: LiA x (B) y Here, A is any one or more selected from the group consisting of iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni), vanadium (V), and titanium (Ti), and B can be any one or more selected from the group consisting of PO4, PO4F, SO4, SO4F, BO3, SiO4, P2O7, MoO4, and WO4. Preferably, A is any one or more selected from the group consisting of iron, cobalt, and manganese, and B can be PO4.

[0050] When A is any one or more selected from the group consisting of iron, cobalt, and manganese, and B is PO4, the polyvalent anion-based lithium positive electrode material has an olivine structure. When the positive electrode material has such an olivine structure, it is superior in the efficiency of the chlorination reaction in the low-temperature region compared to other structures such as a layered structure and a spinel structure, and as a result, a compound containing lithium and a polyvalent anion can be separated from the positive electrode material with high efficiency in the low-temperature region.

[0051] In addition, x and y in Chemical Formula 1 can satisfy 0.5 < x ≤ 3.0 and 0.5 < y ≤ 3.0.

[0052] In addition, the polyvalent anion-based lithium positive electrode material can be any one or more selected from the group consisting of a positive electrode active material containing the compound of Chemical Formula 1, a positive electrode containing the positive electrode active material, and an electrode containing the positive electrode.

[0053] Specifically, the chlorination reaction in step (1) above may proceed at 20 to 280°C, more preferably at 80 to 280°C, and most preferably at 170 to 280°C. The temperature of such a chlorination reaction may be the temperature of the chlorine-containing gas. In this case, if the temperature of the chlorination reaction is less than 80°C, the polyvalent anionic lithium cathode material may not react sufficiently with the chlorine-containing gas, and unreacted polyvalent anionic lithium cathode material may remain. Also, if the temperature of the chlorination reaction is less than 170°C, the chlorination reaction efficiency of lithium contained in the polyvalent anionic lithium secondary battery cathode material may decrease. Furthermore, if the temperature of the chlorination reaction exceeds 280°C, lithium and the compound containing the polyvalent anion may react further, forming another compound containing all of the lithium and the polyvalent anionic compound, making separation of lithium and the polyvalent anionic compound impossible.

[0054] More specifically, as explained later with reference to Table 1, when the reaction temperature is between 80 and 280°C, the reaction rate of the polyvalent anion lithium secondary battery cathode material is superior compared to when the temperature is outside this range. When the reaction proceeds at temperatures below 80°C, some of the polyvalent anion lithium secondary battery cathode material may not react completely, and when the reaction proceeds at temperatures above 280°C, side reactions may occur, resulting in improper separation. Furthermore, when the reaction proceeds particularly between 170 and 280°C, the separation efficiency is significantly better compared to when the temperature is outside this range.

[0055] However, even if polyvalent anionic lithium secondary battery cathode material remains, there is no major problem in recovering lithium chloride through the subsequent dissolution process. Such low-temperature processes have the advantage of reducing energy consumption and extending the lifespan of reactors and ancillary facilities, so they can be applied when necessary, even if it means accepting a partial loss of efficiency. Therefore, even when the chlorination reaction is carried out in the temperature range of 20°C to 280°C, LFP can be separated, and it is superior in terms of economics, such as reducing the energy consumption of the process and extending the lifespan of ancillary facilities.

[0056] Furthermore, when separating lithium from NCM-based cathode materials with a layered crystal structure by chlorination, the reaction proceeds only at temperatures of approximately 450°C or higher due to the crystal structure. Therefore, a large amount of energy is consumed during lithium separation, which is a significant disadvantage from both economic and environmental perspectives. However, when applied to polyvalent anion-based lithium cathode materials that do not have a layered structure, lithium can be separated at relatively lower temperatures due to the difference in crystal structure, thus exhibiting superior performance from both economic and environmental perspectives.

[0057] Furthermore, the chlorination reaction according to the present invention can be carried out for 0.1 to 24 hours under the aforementioned temperature conditions, preferably for 0.3 to 6 hours. In this case, carrying out the chlorination reaction for 0.3 to 6 hours is more efficient than not carrying it out for 0.3 to 6 hours.

[0058] Specifically, the chlorine-containing gas is not limited as long as it can react with the polyvalent anion lithium secondary battery cathode material to form a compound containing lithium chloride and polyvalent anions. Preferably, it may contain one or more selected from the group consisting of chlorine gas (Cl2), hydrogen chloride (HCl), phosgene (COCl2), and carbon tetrachloride (CCl4), and more preferably, it may contain chlorine gas (Cl2).

[0059] More specifically, the chlorine-containing gas can be used by mixing it with a compound containing chlorine at a concentration of 0.1 to 90 volume percent relative to the total weight, along with the remaining gases such as Ar, N2, and O2. The remaining gases may also act as carrier gases. In this case, if the chlorine gas is mixed at a concentration of less than 0.1 volume percent, the efficiency of the chlorination reaction may decrease, and the separation of lithium and other positive electrode materials may not be sufficient. If the chlorine gas is mixed at a concentration exceeding 90 volume percent, there is a risk of damage to the process facilities and a decrease in process efficiency due to the generation of an excess amount of unreacted chlorine gas. This allows for the appropriate selection of the chlorine gas mixing ratio in waste batteries, taking into account the type and content of the positive electrode material.

[0060] Furthermore, the amount of chlorine-containing gas can be appropriately selected depending on the amount of polyvalent anion lithium secondary battery cathode material introduced from the waste battery, and preferably, it can be mixed in a number of moles from 1 to 50 relative to the number of moles of lithium ions in the polyvalent anion lithium secondary battery cathode material. If the amount of chlorine-containing gas is less than 1 mole relative to the number of moles of lithium ions in the polyvalent anion lithium secondary battery cathode material, the desired chlorination reaction may not proceed sufficiently, and the separation efficiency of lithium and compounds containing polyvalent anions may decrease. If the amount of chlorine-containing gas is more than 50 moles relative to the number of lithium ions in the polyvalent anion lithium secondary battery cathode material, the process cost may increase due to the excessive use of chlorine.

[0061] Next, in step (2), the first mixture is brought into contact with a solvent to separate and obtain a second mixture containing a compound with polyvalent anions and lithium chloride and a solvent (S200 in Figure 1).

[0062] Conventional separation methods using strong acids have a problem where separation efficiency decreases due to the similar chemical properties of the positive electrode metal materials. In other words, specific positive electrode metal materials are not separated, and other positive electrode metal materials with similar properties are separated together, requiring further metal separation and purification processes, which reduces separation and recycling efficiency.

[0063] Thus, the present invention solves the aforementioned problems through a simple step of contacting the first mixture with a solvent. More specifically, the lithium chloride produced in step (1) through the chlorination reaction described above has very high solubility in the solvent described later, and dissolves in the solvent through this step, becoming liquid. The polyvalent anionic compounds that do not react with chlorine have almost no solubility in the solvent described later, remain in a solid state, and can be easily separated by washing with the solvent. In other words, the present invention can selectively separate the cathode material metal substance through a simple step of washing and separation using a solvent, taking advantage of the fact that compounds containing polyvalent anions do not dissolve in the solvent after the chlorination reaction, and no further purification step is required.

[0064] Specifically, the solvent is not limited as long as it can dissolve lithium chloride without dissolving the compound containing polyvalent anions, and can come into contact with the first mixture to separate the first mixture into the compound containing polyvalent anions and the second mixture. Preferably, it may contain one or more selected from the group consisting of water, ethanol, methanol, butanol, propanol, hydrazine, methylformaldehyde, acetone, formic acid, pyridine, and benzene, and more preferably, it may be water. When the solvent is water, compared to using other solvents, it has a higher solubility for lithium chloride, can be operated with a relatively small amount, is economical, does not generate other toxic chemicals such as organic waste liquid, and may be advantageous from the viewpoint of environmental compatibility.

[0065] Furthermore, the second mixture may contain some impurities that are typically present.

[0066] The amount of solvent added in step (2) can be appropriately selected considering the amount of the first mixture transferred from step (1), and preferably, it can be mixed in an amount of 000 to 100,000 parts by weight per 100 parts by weight of the total first mixture transferred from step (1).

[0067] Thus, the secondary battery cathode material recycling method according to the present invention allows for easy separation of lithium and polyvalent anions contained in the polyvalent anion lithium cathode material through step (2), while simultaneously realizing an environmentally friendly separation process. Since no further purification process is required, process simplification and cost reduction can be achieved simultaneously.

[0068] Furthermore, the present invention may further include a step after step (2) above in which the solvent is removed to obtain lithium chloride. The method for removing the solvent is not limited as long as it is a method of separating the solvent from the lithium chloride dissolved in the solvent, but preferably it is a method of drying the solvent.

[0069] In this case, the drying step may be carried out at a temperature of 20 to 200°C, and more preferably at a temperature of 50 to 150°C and under vacuum conditions. This can be appropriately selected considering the type and properties of the solvent contained in the second mixture.

[0070] Furthermore, the present invention provides a method for recycling a polyvalent anion lithium secondary battery cathode material by separating it into lithium carbonate. Figure 2 is a flowchart schematically showing a method for recycling a polyvalent anion lithium secondary battery cathode material by separating it into lithium carbonate according to one embodiment of the present invention, and the present invention will be specifically described below with reference to the same figure. In this case, parts that overlap with the previously described method for recycling a polyvalent anion lithium secondary battery cathode material will be omitted.

[0071] First, after performing steps (1) and (2) of the aforementioned recycling method for polyvalent anion lithium secondary battery cathode material, step (3) is performed, in which the second mixture is reacted with a carbonate to form a third mixture containing lithium carbonate (Li2CO3) (S300 in Figure 2).

[0072] Specifically, in step (3), the second mixture reacts with the carbonate, and lithium carbonate (Li2CO3) containing lithium and a salt containing chlorine may be formed as products. In this case, the carbonate is not limited as long as it can react with the lithium chloride of the second mixture to form a salt containing lithium carbonate and chlorine, but it is preferably one of either sodium carbonate (Na2CO3) or potassium carbonate (K2CO3), and more preferably sodium carbonate.

[0073] The chlorine-containing salt may, for example, be sodium chloride (NaCl) if the carbonate is sodium carbonate.

[0074] The amount of carbonate can be appropriately selected considering the amount of the second mixture formed in step (2), and preferably, it can be mixed in an amount of 0.5 to 5 times the expected number of moles of lithium in the second mixture formed in step (2). In this case, if the amount of carbonate is less than 0.5 times the expected number of moles of lithium in the second mixture, a sufficient amount of lithium carbonate may not be formed, resulting in a problem of reduced separation efficiency. If the amount of carbonate is more than 5 times the expected number of moles of lithium, the amount of carbonate is too high, and subsequent washing and further purification steps may be required.

[0075] Next, in step (4), lithium carbonate is separated from the third mixture (S400 in Figure 2).

[0076] The method for separating the lithium carbonate is not limited as long as it can separate the lithium carbonate from the chlorine-containing salt, but preferably it is a solid-liquid separation method that uses the difference in solubility between the lithium carbonate and the chlorine-containing salt.

[0077] Specifically, lithium carbonate has low solubility in the solvent contained in the third mixture, while the chlorine-containing salt has high solubility in the solvent contained in the third mixture. By using this difference in solubility to perform solid-liquid separation, lithium carbonate can be separated.

[0078] In this case, the solvent contained in the third mixture is completely dried, and a second solvent is added to separate the lithium carbonate and chlorine-containing salt. The difference in solubility in the second solvent can be used to separate the lithium carbonate and chlorine-containing salt. The second solvent is not limited as long as it can dissolve the chlorine-containing salt without dissolving the lithium carbonate in order to separate the lithium carbonate and chlorine-containing salt. Preferably, water, alcohol, ammonia, etc., can be used, and most preferably, water or methanol can be used. In this case, the large difference in solubility between lithium carbonate and the chlorine-containing salt may be advantageous in that it is possible to separate high-purity lithium carbonate.

[0079] Furthermore, the amount of the second solvent used can be appropriately selected considering the amount of lithium carbonate and chlorine-containing salt contained in the third mixture, and more preferably, the second solvent may be added in an amount of 1,000 to 100,000 parts by weight per 100 parts by weight of the total third mixture.

[0080] In this process, the drying step may be carried out at a temperature of 20 to 200°C, and more preferably at a temperature of 50 to 150°C and under vacuum conditions. This can be appropriately selected considering the type and properties of the solvent contained in the third mixture.

[0081] Furthermore, according to a preferred embodiment of the present invention, the separated lithium carbonate can be further dried to remove the small amount of solvent contained therein.

[0082] Furthermore, the lithium carbonate obtained through the aforementioned process can be used as a lithium compound to be added to the fifth mixture in the resynthesis process described later.

[0083] Furthermore, the present invention provides a method for recycling a polyvalent anionic lithium cathode material by separating it into lithium hydroxide. Figure 3 is a flowchart schematically showing a method for recycling a polyvalent anionic lithium cathode material by separating it into lithium hydroxide according to one embodiment of the present invention, and the present invention will be specifically described below with reference to the same figure. In this case, parts that overlap with the previously described method for recycling polyvalent anionic lithium cathode material will be omitted.

[0084] First, after performing steps (1) to (4) of the aforementioned polyvalent anion lithium cathode material recycling method, step (5) is performed, in which the lithium carbonate is reacted with calcium hydroxide to obtain a fourth mixture containing lithium hydroxide (LiOH) and calcium carbonate (CaCO3) (S500 in Figure 3).

[0085] Specifically, the lithium carbonate can react with calcium hydroxide to form lithium hydroxide and calcium carbonate.

[0086] In this case, the calcium hydroxide may consist of calcium hydroxide alone or may further contain a solvent. In this case, the solvent is not limited as long as it is a solvent that allows the two compounds to be separated by the difference in solubility, as lithium hydroxide has high solubility and calcium carbonate has low solubility in the solvent described later in step (6), but water is preferred.

[0087] Specifically, the calcium hydroxide may contain 1,000 to 100,000 parts by weight of the solvent per 100 parts by weight of the total calcium hydroxide.

[0088] Furthermore, the amount of calcium hydroxide can be appropriately selected considering the amount of lithium carbonate formed in step (4), and preferably, it can be mixed in a number of moles equal to 0.5 to 5 times the number of moles of lithium carbonate formed in step (4). In this case, if the amount of calcium hydroxide is less than 0.5 times the number of moles of lithium carbonate, a sufficient amount of lithium hydroxide may not be formed, resulting in a problem of reduced separation efficiency. If the amount of calcium hydroxide is more than 5 times the number of moles of lithium carbonate, the amount of calcium hydroxide may be too high, requiring subsequent washing and further purification steps.

[0089] Next, in step (6), lithium hydroxide is separated from the fifth mixture (S600 in Figure 3).

[0090] The method for separating the lithium hydroxide is not limited as long as it can separate the solution containing lithium hydroxide from calcium carbonate, but preferably it is a solid-liquid separation method that uses the difference in solubility between lithium hydroxide and calcium carbonate.

[0091] Specifically, calcium carbonate has low solubility in the solvent contained in the fourth mixture, while lithium hydroxide has high solubility in the same solvent. By using this difference in solubility to separate the solid and liquid, the solution containing lithium hydroxide can be separated. In this case, as mentioned above, the solvent is not limited as long as it can separate the two compounds due to the difference in solubility, since lithium hydroxide has high solubility in that solvent and calcium carbonate has low solubility. However, water is preferred.

[0092] Furthermore, the present invention may further include a step after step (6) in which the solvent is removed to obtain lithium hydroxide. The method for removing the solvent is not limited as long as it is a method of separating the solvent from the lithium hydroxide dissolved in the solvent, but preferably it is a method of drying the solvent.

[0093] In this case, the drying step may be carried out at a temperature of 20 to 200°C, and more preferably at a temperature of 50 to 150°C and under vacuum conditions. This can be appropriately selected considering the type and properties of the solvent contained in the fourth mixture.

[0094] Furthermore, the lithium hydroxide obtained through the aforementioned process can be used as a lithium compound to be added to the fifth mixture in the resynthesis process described later.

[0095] Furthermore, the present invention provides a method for recycling polyvalent anionic lithium cathode material by resynthesizing a new polyvalent anionic lithium cathode material. Figure 4 is a flowchart showing a method for recycling polyvalent anionic lithium cathode material by resynthesizing a new polyvalent anionic lithium cathode material according to one embodiment of the present invention, and the present invention will be specifically described below with reference to the same figure. In this description, parts that overlap with the previously described method for recycling polyvalent anionic lithium cathode material will be omitted.

[0096] First, after performing steps (1) and (2) of the aforementioned polyvalent anion lithium cathode material recycling method, step (7) involves adding a lithium compound to the compound containing the polyvalent anion to form a fifth mixture (S700 in Figure 4).

[0097] The lithium mixture is not limited as long as it can be resynthesized into a polyvalent anionic lithium cathode material by reacting with a compound containing a polyvalent anion contained in the second mixture through a process described later, but preferably it may contain one or more selected from the group consisting of lithium carbonate, lithium hydroxide, lithium nitrate, lithium sulfate, lithium acetate, and lithium oxalate.

[0098] Furthermore, the lithium compound may include lithium carbonate or lithium hydroxide obtained by the recycling method for the polyvalent anion lithium cathode material of the present invention.

[0099] Specifically, the amount of lithium compound can be appropriately selected considering the amount of the compound containing polyvalent anions formed in step (2). Preferably, the amount of lithium ions in the lithium compound can be added so that the number of moles of lithium ions in the lithium compound is 80-200% of the number of moles of metal ions in the compound containing polyvalent anions formed in the second mixture in step (2), and more preferably, it can be added so that it is 100-120%. In this case, if the number of moles of lithium ions in the lithium compound is added so that it is less than 100% of the number of moles of metal ions in the compound containing polyvalent anions, a cathode material lacking lithium may be formed. If it is added so that it exceeds 120%, impurities may be formed or an excess amount of lithium compound may precipitate.

[0100] Next, in step (8), the fifth mixture is reacted to reform the phase of the polyvalent anion lithium secondary battery cathode material (S800 in Figure 4).

[0101] Specifically, the compound containing polyvalent anions in the fifth mixture reacts with the lithium compound to reform the phase of the polyvalent anion-based lithium cathode material.

[0102] Reforming the phase of the polyvalent anion-based lithium secondary battery cathode material means inducing the decomposition of the lithium compound at the decomposition temperature of the lithium compound to induce the synthesis of the cathode material. More specifically, this may be a process of maintaining a sufficient time at the decomposition temperature of the lithium compound to uniformly insert lithium into the structure of the compound containing the polyvalent anion.

[0103] The method for reforming the phase of the polyvalent anion-based lithium secondary battery cathode material is not limited as long as it is a method that uniformly carries out the process of a compound containing a polyvalent anion reacting with a lithium compound to form a polyvalent anion-based lithium cathode material, but preferably it is a process of reacting at a temperature of 200 to 400°C for 1 to 24 hours.

[0104] More specifically, this reformation process is carried out at a lower temperature than the resynthesis process by improving the crystallinity of the cathode material described later, and serves to prevent the synthesis of non-uniform cathode material and the generation of impurities due to the reductive decomposition reaction of the cathode material. In this case, if the temperature of the reformation process is below 200°C, there is a problem that the thermal energy will be insufficient and the efficiency of the cathode material synthesis reaction will be too low, and if the temperature of the reformation process exceeds 400°C, there is a problem that the reaction will not occur uniformly.

[0105] Subsequently, in step (9), the crystallinity of the fifth mixture is improved to resynthesize a polyvalent anion lithium secondary battery cathode material with excellent electrochemical activity (S900 in Figure 4).

[0106] Specifically, the method for resynthesizing a polyvalent anionic lithium secondary battery cathode material with improved crystallinity and excellent electrochemical activity is not limited as long as it can improve the crystallinity of the reaction product formed in step (8) above, but preferably it is a process of reacting at a temperature of 500 to 850°C for 1 to 24 hours. At temperatures below 500°C, the effect of improving crystallinity may decrease, and at temperatures above 850°C, impurities may be formed.

[0107] More specifically, a polyvalent anion lithium cathode material can be resynthesized through the aforementioned process.

[0108] Furthermore, the resynthesized polyvalent anion lithium cathode material can have an initial discharge capacity of 100 mAh / g or more.

[0109] Furthermore, the present invention provides a polyvalent anion lithium cathode material recycling apparatus that embodies the polyvalent anion lithium cathode material recycling method described above. Figure 5 is a diagram showing an apparatus for recycling polyvalent anion lithium cathode material according to one embodiment of the present invention, and the present invention will be described in detail below with reference to this figure. In this case, parts that overlap with the polyvalent anion lithium cathode material recycling method described above will be omitted.

[0110] The present invention provides a recycling apparatus for polyvalent anion lithium secondary battery cathode material, comprising: a first reaction unit that chlorinates polyvalent anion lithium cathode material separated from a battery with a chlorine-containing gas to form a first mixture containing a polyvalent anion compound and lithium chloride; and a first separation unit that communicates with the first reaction unit and separates and obtains a second mixture containing a polyvalent anion compound, lithium chloride and solvent by contacting the first mixture with a solvent.

[0111] In the first reaction section 110, a chlorination reaction is performed to separate the lithium chloride and the compound containing polyvalent anions.

[0112] More specifically, in the first reaction unit 110, the polyvalent anion lithium cathode material separated from the battery can be subjected to a chlorination reaction with a chlorine-containing gas to obtain a first mixture containing a polyvalent anion and lithium chloride. That is, the lithium in the polyvalent anion lithium cathode material can be converted into lithium chloride and obtained, and the remaining compound can be separated in the form of a compound containing polyvalent anions.

[0113] Accordingly, the first reaction unit 110 may further include a separate gas injection unit (not shown) for injecting the chlorine-containing gas. Furthermore, since the chlorination reaction in the first reaction unit 110 involves the reaction of a polyvalent anionic lithium cathode material with the gas under high-temperature conditions, the first reaction unit 110 may further include a heater (not shown) for maintaining the high-temperature state. The shape and material of the injection unit and heater are not particularly limited, as long as they are conventional and serve the purpose of the present invention.

[0114] Next, the first separation unit 120 is in communication with the first reaction unit 110, and the first mixture is brought into contact with the solvent to form a second mixture containing a compound with polyvalent anions, lithium chloride, and the solvent.

[0115] More specifically, the first mixture formed in the first reaction section 110 may be transferred to the first separation section 120 via a transfer path (not shown). The transferred first mixture comes into contact with a solvent, where lithium chloride dissolves in the solvent and is converted into a liquid. Compounds containing polyvalent anions that do not react with chlorine remain in a solid state and can be easily separated by washing through the solvent.

[0116] Accordingly, the first separation unit 120 may further include a solvent injection unit (not shown) for injecting a solvent, and the shape and material of such an injection unit are not particularly limited as long as they are in line with the purpose of the present invention.

[0117] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a second reaction unit communicating with the first separation unit and reacting the second mixture with a carbonate to form a third mixture containing lithium carbonate, and a second separation unit communicating with the second reaction unit and separating lithium carbonate from the third mixture. Figure 6 is a diagram showing an apparatus for recycling polyvalent anion lithium cathode material according to one embodiment of the present invention, and the present invention will be specifically described below with reference to this figure. In this case, parts that overlap with the above-described method and apparatus for recycling polyvalent anion lithium secondary battery cathode material will be omitted from the description.

[0118] First, the second reaction section 130 is in communication with the first separation section 120, and the second mixture can be reacted with a carbonate to form a third mixture containing lithium carbonate.

[0119] More specifically, the second mixture containing lithium chloride, which is dissolved in a solvent and present in liquid form in the first separation unit 120, may be transferred to the second reaction unit 130 via a transfer path (not shown). The transferred second mixture may react with a carbonate to obtain a third mixture containing lithium carbonate and a salt containing chlorine as products.

[0120] As a result, the second reaction unit 130 may have carbonate prepared in advance for reaction with the second mixture transferred from the first separation unit 120, but is not limited to this, and carbonate may be injected via a further injection unit (not shown).

[0121] Next, the second separation unit 140 communicates with the second reaction unit 130 to separate the third mixture and obtain lithium carbonate.

[0122] More specifically, the third mixture containing a salt containing lithium carbonate and chlorine, formed by the reaction of the carbonate in the second reaction section 130, can be transferred to the second separation section 140 via a transfer path (not shown). In the transferred third mixture, the chlorine-containing salt is dissolved in the solvent and exists in liquid form, while the lithium carbonate, having low solubility in the solvent, remains in a solid state and can be easily separated and obtained by washing the lithium carbonate through the solvent.

[0123] More specifically, the lithium can be selectively recovered by separating the lithium carbonate and chlorine-containing salt contained in the third mixture in the second separation unit 140. In particular, the third mixture containing the solvent can be dried, and some or all of the solvent contained therein can be removed, allowing the lithium carbonate and chlorine-containing salt present in solution in the third mixture to be separated based on the difference in their solubility in the solvent.

[0124] Accordingly, the second separation section 140 may further include a solvent injection section (not shown) for injecting a solvent, and the shape and material of such an injection section are not particularly limited, as long as they are in line with the purpose of the present invention.

[0125] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a third reaction unit communicating with the second separation unit and reacting the lithium carbonate with calcium hydroxide to form a fourth mixture containing lithium hydroxide and calcium carbonate, and a third separation unit 160 communicating with the third reaction unit 150 and separating the lithium carbonate from the fourth mixture. Figure 7 is a diagram showing an apparatus for recycling polyvalent anion lithium cathode material according to one embodiment of the present invention, and the present invention will be specifically described below with reference to this figure. In this case, parts that overlap with the above-described method and apparatus for recycling polyvalent anion lithium secondary battery cathode material will be omitted from the description.

[0126] First, the third reaction section 150 is in communication with the second separation section 140, and lithium carbonate can be reacted with calcium hydroxide to form a fourth mixture containing lithium hydroxide and calcium carbonate.

[0127] More specifically, the lithium carbonate separated in the second separation unit 140 may be transferred to the third reaction unit 150 via a transfer path (not shown), and the transferred lithium carbonate may react with calcium hydroxide to obtain a fourth mixture containing lithium hydroxide and calcium carbonate as a product.

[0128] As a result, the third reaction unit 150 may have calcium hydroxide prepared in advance for reacting with lithium carbonate transferred from the second separation unit 140, but is not limited to this, and calcium hydroxide may be injected via a further injection unit (not shown).

[0129] In this case, the calcium hydroxide may consist of calcium hydroxide alone or may further contain a solvent. In this case, the solvent is not limited as long as it is a solvent that can separate the two compounds due to the difference in solubility, as lithium hydroxide has high solubility and calcium carbonate has low solubility in the third separation section described later, but water is preferred.

[0130] Accordingly, the third reaction section 150 may further include a solvent injection section (not shown) for injecting a solvent, and the shape and material of such an injection section are not particularly limited, as long as they are in line with the objectives of the present invention.

[0131] Next, the third separation unit 160 communicates with the third reaction unit 150, allowing for the separation of lithium hydroxide from the fourth mixture.

[0132] More specifically, the fourth mixture containing lithium hydroxide and calcium carbonate, formed by the reaction of calcium hydroxide with calcium hydroxide in the third reaction section 150, can be transferred to the third separation section 160 via a transfer path (not shown). The lithium hydroxide in the transferred fourth mixture is dissolved in the solvent and exists in liquid form, while the calcium carbonate, having low solubility in the solvent, remains in a solid state and can be easily separated by washing through the solvent.

[0133] Accordingly, the third separation section 160 may further include a solvent injection section (not shown) for injecting a solvent, and the shape and material of such an injection section are not particularly limited, as long as they are in line with the purpose of the present invention.

[0134] Furthermore, the recycling apparatus for polyvalent anion lithium secondary battery cathode material according to the present invention may further include a synthesis unit 170 that communicates with the first separation unit 120, the second separation unit 140, and the third separation unit 160, and resynthesizes the polyvalent anion lithium secondary battery cathode material from the compound containing polyvalent anions, lithium carbonate, and lithium hydroxide separated in the first separation unit 120, the second separation unit 140, and the third separation unit 160. Figure 8 is a diagram showing an apparatus for recycling polyvalent anion lithium cathode material according to one embodiment of the present invention, and the present invention will be specifically described below with reference to this figure. In this case, parts that overlap with the above-described method and apparatus for recycling polyvalent anion lithium secondary battery cathode material will be omitted from the description.

[0135] More specifically, the compound containing polyvalent anions separated in the first separation unit 120 may be transferred to the synthesis unit 170 via a transfer path (not shown), and the transferred compound containing polyvalent anions may be resynthesized into a polyvalent anion-based lithium secondary battery cathode material by reacting with a lithium compound.

[0136] In this case, the lithium compound is not limited as long as it can be reacted with the compound containing the polyvalent anion to be resynthesized into a polyvalent anion-based lithium secondary battery cathode material, but preferably it is one or more selected from the group consisting of lithium carbonate and lithium hydroxide. Furthermore, in the synthesis unit 170, a lithium compound for reacting with the transferred compound containing the polyvalent anion may be prepared in advance, but is not limited thereto, and the lithium compound may be injected via a further injection unit (not shown).

[0137] Furthermore, the lithium compound may be lithium carbonate separated in the second separation unit 140, lithium hydroxide separated in the third separation unit 160, or a mixture of the two compounds. In this case, the lithium carbonate separated in the second separation unit 140 may be transferred to the synthesis unit 170 via a transfer path (not shown), and the lithium hydroxide separated in the third separation unit 160 may also be transferred to the synthesis unit 170 via a transfer path (not shown).

[0138] Furthermore, since the reaction may occur at high temperatures in the synthesis section 170, a heater (not shown) for maintaining the high temperature state may be included. The shape and material of the heater may be ordinary as long as they are in line with the purpose of the present invention, and are not particularly limited. [Examples]

[0139] The present invention will be described more specifically based on the following examples, but these examples are not intended to limit the scope of the present invention, and should be understood as being helpful in understanding the present invention.

[0140] <Example 1 - LFP powder unit recycling experiment> (1) Reaction rate (%) of lithium and impurity detection based on reaction time and temperature Lithium separation experiments were conducted using LFP powder, a polyvalent anion-based lithium secondary battery cathode material. Commercial LFP powder (1 g) was prepared as the polyvalent anion-based lithium secondary battery cathode material. Next, the prepared sample was subjected to halogenation reactions under the conditions of Cl2 (10-30 sccm) and Ar (170-190 sccm) (carrier gas) at different temperatures and times as shown in Table 1 below. After the reaction, the mass of the total product containing lithium chloride and polyvalent anion compounds (FP, FePO4) and the reaction rate of lithium are shown in Table 1. The reaction rate of lithium was calculated by dividing the number of moles of chlorine that reacted by the number of moles of lithium present in the reactant, under the assumption that chlorine reacts in proportion to the increase in mass. Furthermore, after dissolving the total product in 250 ml of water (H2O), the components of the undissolved solid product were analyzed using X-ray diffraction (XRD), and the results are shown in Table 1.

[0141] [Table 1]

[0142] As a result, as is clear from Table 1, the presence of the FP phase was confirmed in the temperature range from room temperature to 250°C. This indicates that the chlorination reaction of LFP proceeds even at room temperature, and LiCl is formed. However, in the low temperature range below 80°C, it was confirmed that the LFP phase remains while the lithium reaction rate decreases. In other words, when the reaction proceeds at a temperature between 80°C and 280°C, the LFP reacts completely, no impurities are generated, and the reaction efficiency is high, making it superior.

[0143] However, even if the LFP phase remains, there is no major problem in recovering LiCl through the subsequent dissolution process. Such low-temperature processes have the advantage of reducing energy consumption and extending the lifespan of reactors and ancillary facilities, so they can be applied when necessary, even if it means accepting some loss of efficiency. Therefore, even when chlorination reactions are carried out in the temperature range of 20°C to 280°C, LFP can be separated, and it is economically advantageous in that it reduces the energy consumption of the process and extends the lifespan of ancillary facilities.

[0144] Furthermore, when the reaction was carried out for 4 hours, it was found that when the reaction was carried out at a temperature exceeding 280°C, impurities such as LiFeP2O7, Li3Fe2(PO4)3, and an unknown compound were generated by side reactions and remained insoluble in the solvent. Moreover, these impurities contained lithium and polyvalent anionic compounds. This confirms that when the reaction temperature exceeds 280°C, the separation of lithium and polyvalent anionic compounds contained in the positive electrode material of a polyvalent anionic lithium secondary battery does not occur properly.

[0145] In addition, when the reaction is carried out for 4 hours, it can be confirmed that the reaction rate of lithium is significantly better when the reaction temperature is between 170°C and 280°C compared to when the reaction temperature is outside this range.

[0146] Furthermore, when the reaction was carried out at a reaction temperature of 200°C with varying reaction times, it was confirmed that the lithium reaction rate was low when the reaction time was less than 0.3 hours. Therefore, when the reaction time is 0.3 hours or longer, the recycling efficiency of the polyvalent anion lithium secondary battery cathode material is excellent.

[0147] (2) XRD analysis before and after solid-liquid separation In the case where the reaction was carried out at a temperature of 200°C for 4 hours as shown in Table 1, X-ray diffraction experiments were performed on all products, and the results are shown in Figure 9. Furthermore, after dissolving all products in 250 ml of water, X-ray diffraction experiments were carried out on the undissolved solid products, and the results are shown in Figure 10.

[0148] As is clear from Figure 9, LiCl and FePO4 were produced by the chlorination reaction. Furthermore, as is clear from Figure 10, the produced LiCl completely dissolved in water, and only FePO4 remained as a solid product after dissolution. This confirms that lithium and the polyvalent anionic compound can be separated into lithium chloride and the polyvalent anionic compound by the chlorination reaction of the polyvalent anionic lithium secondary battery cathode material, and that the produced lithium chloride and polyvalent anionic compound can be easily separated after the chlorination reaction using solid-liquid separation through a solvent.

[0149] (3) Analysis of lithium content in recovered solid-state fission products In the cases where the reaction was carried out for 4 hours at temperatures of 50°C, 100°C, 150°C, 200°C, and 250°C as shown in Table 1, the total product was dissolved in water, and the molar ratio of Li / Fe was measured using inductively coupled plasma analysis on the undissolved solid product. The results are shown in Table 2.

[0150] [Table 2]

[0151] As is clear from Table 2, the proportion of lithium in the recovered solid-state product decreased significantly compared to the initial sample, confirming that the separation of lithium and polyvalent anionic compounds was successful.

[0152] (4) Analysis of the lithium, iron, and phosphoric acid content of the recovered lithium chloride aqueous solution. In the case where the reaction was carried out for 4 hours at temperatures of 50°C, 100°C, 150°C, 200°C, and 250°C as shown in Table 1, the amounts of lithium, iron, and phosphorus in the solution after dissolving all the products in water, and the resulting purity of lithium were measured, and the results are shown in Table 3. The purity of lithium is calculated as the percentage of the lithium content relative to the total content of lithium, iron, and phosphorus listed below.

[0153] [Table 3]

[0154] As is clear from Table 3, it can be confirmed that lithium is present in very high purity in the dissolved solution after the chlorination reaction. This shows that lithium can be extracted in high purity simply by contacting the product with a solution after the chlorination reaction.

[0155] <Example 2 - LFP electrode unit recycling experiment> Electrodes containing commercial LFP, carbon conductor, polymer binder, and Al conductive material were prepared. These electrodes were obtained by uniformly coating the Al conductive material with a slurry in which 90% LFP, 5% Super-P carbon black, and 5% PVDF binder were homogeneously mixed in an NMP organic solvent, followed by a drying process to volatilize the NMP. Next, the prepared samples were subjected to a chlorination reaction at 200°C for 1 hour under the conditions of Cl2 (10 sccm) and Ar (190 sccm) (carrier gas). After the chlorination reaction, the powder separated from the Al conductive material was dissolved in 250 ml of water. Photographs of the reaction process are shown in Figure 11. After dissolving the powder in water, X-ray diffraction analysis was performed on the insoluble substances, as shown in Figure 12.

[0156] First, as is clear from Figure 11, even in the case of polyvalent anionic lithium secondary battery cathode materials existing in electrode form, it can be confirmed that lithium and polyvalent anionic compounds can be easily separated from the electrode assembly in powder form by chlorination reaction. Furthermore, as is clear from Figure 12, since lithium is not present in the insoluble substance remaining after dissolution in water, lithium and polyvalent anionic compounds can be easily separated by solid-liquid separation.

[0157] <Example 3 - LFP Cathode Material Resynthesis Experiment> For the resynthesis of the LFP cathode material, FePO4, the residual compound of the LFP cathode material chlorinated at 200°C for 10 minutes under the same conditions as in Example 1 of the present invention, was prepared. Next, 0.5 g of the recycled FePO4 was mixed with LiOH·H2O. At this time, the ratio of moles of Li to moles of Fe was 1.03. Next, the mixed sample was reacted at 350°C for 12 hours under conditions of 96.5 vol% argon (Ar) and 3.5 vol% hydrogen (H2). After that, the obtained product was reacted at 600°C for 12 hours under Ar conditions. Subsequently, X-ray diffraction analysis and electrochemical performance evaluation were performed on the obtained product, and the results are shown in Figures 13 and 14, respectively. As can be seen from Figure 13, even when only the 350°C heat treatment was performed, the LFP phase was formed, but defects were present inside the material, and as can be seen from Figure 14, the electrochemical activity decreased. Furthermore, as can be seen in Figure 13, subsequent heat treatment at 600°C removed defects within the material and improved crystallinity, resulting in increased electrochemical activity, as can be seen in Figure 14.

[0158] As can be seen from Figure 14, when the steps of reforming the phase of the cathode material and improving its crystallinity were carried out sequentially, it was confirmed that a cathode material with an excellent initial discharge capacity of 100 mAh / g or more at a current density of 170 mA / g was resynthesized.

[0159] As can be seen from Figure 15, we confirmed that the LFP phase is effectively formed even when the number of moles of Li relative to Fe is changed to 1.05.

Claims

1. (1) A step of forming a first mixture containing a polyvalent anion-based lithium secondary battery cathode material separated from the battery by chlorination reaction with a chlorine-containing gas to form a compound containing a polyvalent anion and lithium chloride (LiCl); (2) A method for recycling a polyvalent anion lithium secondary battery cathode material, comprising the step of contacting the first mixture with a solvent to separate and obtain a compound containing a polyvalent anion and a second mixture containing lithium chloride and a solvent.

2. The method for recycling a polyvalent anionic lithium secondary battery cathode material according to claim 1, further comprising the step of removing the solvent from the second mixture after step (2) above to obtain lithium chloride.

3. In step (1) above, the polyvalent anion lithium secondary battery cathode material is LiA ｘ (PO ４ ) ｙ A method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 1, characterized in that: Here, A is one or more selected from the group consisting of iron (Fe), cobalt (Co), manganese (Mn), and nickel (Ni), and x and y satisfy 0.5 < x ≤ 3 and 0.5 < y ≤ 3.

4. The method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 1, characterized in that the chlorination reaction temperature is 20 to 280°C.

5. The method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 1, characterized in that the chlorination reaction temperature is 170 to 280°C.

6. The chlorine-containing gas is chlorine gas (Cl ２ ), hydrogen chloride (HCl), phosgene (COCl) ２ ), carbon tetrachloride (CCl ４ A method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 1, characterized by including one or more selected from the group consisting of ).

7. The method for recycling a polyvalent anionic lithium secondary battery cathode material according to claim 1, characterized in that the solvent comprises one or more selected from the group consisting of water, ethanol, methanol, butanol, propanol, hydrazine, methylformaldehyde, acetone, formic acid, pyridine, and benzene.

8. (1) A step of forming a first mixture containing a polyvalent anion-based lithium secondary battery cathode material separated from the battery by chlorination reaction with a chlorine-containing gas to form a compound containing a polyvalent anion and lithium chloride (LiCl); (2) A step of contacting the first mixture with a solvent to separate and obtain a compound containing a polyvalent anion and a second mixture containing lithium chloride and a solvent; (3) The second mixture is reacted with a carbonate to obtain lithium carbonate (Li ２ CO ３ The step of forming a third mixture containing ) and (4) A method for recycling a polyvalent anionic lithium secondary battery cathode material, comprising the step of separating lithium carbonate from the third mixture.

9. (1) A step of forming a first mixture containing a polyvalent anion-based lithium secondary battery cathode material separated from the battery by chlorination reaction with a chlorine-containing gas to form a compound containing a polyvalent anion and lithium chloride (LiCl); (2) A step of contacting the first mixture with a solvent to separate and obtain a compound containing a polyvalent anion and a second mixture containing lithium chloride and a solvent; (3) reacting the second mixture with a carbonate to form a third mixture containing lithium carbonate (Li ２ CO ３ ); and (4) A step of separating lithium carbonate from the third mixture; (5) The lithium carbonate is reacted with calcium hydroxide to produce lithium hydroxide (LiOH) and calcium carbonate (CaCO3). ３ A step of obtaining a fourth mixture containing ) and (6) A method for recycling a polyvalent anionic lithium secondary battery cathode material, comprising the step of separating lithium hydroxide from the fourth mixture.

10. After step (2) above, (7) A step of adding a lithium compound to the compound containing the polyvalent anion to form a fifth mixture; (8) A step of reacting the fifth mixture to reform the phase of the polyvalent anion lithium secondary battery cathode material; and (9) A method for recycling a polyvalent anionic lithium secondary battery cathode material according to claim 9, further comprising the step of improving the crystallinity of the fifth mixture to resynthesize it into a polyvalent anionic lithium secondary battery cathode material with excellent electrochemical activity.

11. The method for recycling a polyvalent anionic lithium secondary battery cathode material according to claim 10, characterized in that the lithium compound is lithium carbonate separated from the third mixture in step (4) or lithium hydroxide (LiOH) separated from the fourth mixture in step (6).

12. The method for recycling a polyvalent anion-based lithium secondary battery cathode material according to claim 10, characterized in that the number of moles of lithium ions in the lithium compound is 100 to 120% of the number of moles of metal ions in the compound containing the polyvalent anion.

13. The method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 10, characterized in that step (8) is to react the fifth mixture at a temperature of 200 to 400°C for 1 to 24 hours.

14. The method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 10, characterized in that step (9) is to react the fifth mixture at a temperature of 500 to 850°C for 1 to 24 hours.

15. The method for recycling a polyvalent anion lithium secondary battery cathode material according to claim 10, characterized in that the resynthesized polyvalent anion lithium secondary battery cathode material has an initial discharge capacity of 100 mAh / g or more.

16. A first reaction unit in which a polyvalent anion-based lithium secondary battery cathode material separated from a battery is subjected to a chlorination reaction with a chlorine-containing gas to form a first mixture containing a polyvalent anion compound and lithium chloride, A recycling apparatus for polyvalent anion lithium secondary battery cathode material, comprising: a first separation unit communicating with the first reaction unit, which contacts the first mixture with a solvent to separate and obtain a compound containing polyvalent anions and a second mixture containing lithium chloride and a solvent.

17. A second reaction section, which is in communication with the first separation section, reacts the second mixture with a carbonate to form a third mixture containing lithium carbonate, The recycling apparatus for polyvalent anion lithium secondary battery cathode material according to claim 16, further comprising a second separation unit which communicates with a second reaction unit and separates lithium carbonate from the third mixture.

18. It communicates with the second separation section, and the lithium carbonate reacts with calcium hydroxide to produce lithium hydroxide (LiOH) and calcium carbonate (CaCO3). ３ A third reaction section that forms a fourth mixture containing ) The recycling apparatus for polyvalent anion lithium secondary battery cathode material according to claim 17, further comprising a third separation unit which communicates with the third reaction unit and separates lithium hydroxide from the fourth mixture.

19. The recycling apparatus for polyvalent anion-based lithium secondary battery cathode material according to claim 18, further comprising a synthesis unit that communicates with a first separation unit, a second separation unit, and a third separation unit, and resynthesizes a polyvalent anion-based lithium secondary battery cathode material from a compound containing polyvalent anions separated in the first separation unit, the second separation unit, and the third separation unit, lithium carbonate, and lithium hydroxide.

20. The recycling apparatus for polyvalent anion lithium secondary battery cathode material according to claim 16, characterized in that the first reaction unit further includes a gas injection unit for injecting gas into the first reaction unit.

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