Method for recovering active metals from lithium secondary batteries

Abstract

In a method for recovering active metals for lithium secondary batteries, a sulfated active material solution is prepared by adding a sulfuric acid solution to a lithium metal composite oxide. The transition metals are extracted from the sulfated active material solution. A lithium extractant is added to the remaining solution after the transition metals have been extracted from the sulfated active material solution to recover a lithium precursor. This method reduces the amount of impurities and provides a high-yield lithium precursor recovery method that allows for the recycling of sulfuric acid and neutralizing agents.

Description

[Technical Field]

[0001] This invention relates to a method for recovering active metals from lithium secondary batteries. More specifically, it relates to a method for recovering active metals from lithium secondary batteries using acidic and basic solutions. [Background technology]

[0002] In recent years, rechargeable batteries have been widely applied and developed as power sources for portable electronic communication devices such as camcorders, mobile phones, and laptop computers, as well as for vehicles such as hybrid and electric vehicles. Among rechargeable batteries, lithium-ion batteries have been actively developed and applied due to their high operating voltage and energy density per unit weight, as well as their advantages in charging speed and weight reduction.

[0003] A lithium metal oxide can be used as the positive electrode active material for the lithium secondary battery. The lithium metal oxide may further contain transition metals such as nickel, cobalt, and manganese.

[0004] Because the aforementioned high-cost valuable metals are used in the positive electrode active material, the manufacturing of the positive electrode material accounts for more than 20% of the total manufacturing cost. Furthermore, with the growing concern for environmental protection in recent years, research into recycling methods for positive electrode active materials is progressing.

[0005] For example, a wet process was used in which valuable metals were sequentially recovered by leaching waste cathode active material with a strong acid. However, such a wet process can lead to a decrease in regeneration selectivity due to by-products from solution reactions and environmental pollution. Furthermore, because large amounts of solution are used, it may not be possible to provide sufficient recycling characteristics from the standpoint of process efficiency and lithium recovery rate.

[0006] For example, Korean Patent No. 10-0709268 discloses a recycling apparatus and method for waste manganese batteries and alkaline batteries. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a method for recovering active metals from lithium secondary batteries that has improved reaction efficiency and process reliability. [Means for solving the problem]

[0008] In the method for recovering active metals from a lithium secondary battery according to an embodiment of the present invention, a sulfated active material solution can be produced by adding sulfuric acid to a lithium metal composite oxide. A transition metal can be extracted from the sulfated active material solution. A lithium extractant can be added to the residual solution from which the transition metal has been extracted from the sulfated active material solution to recover a lithium precursor.

[0009] In some embodiments, the transition metal can be extracted by adding a transition metal extractant containing an alkyl phosphate compound, an alkylphosphonic acid compound, an alkylphosphinic acid compound, or a carboxylic acid compound to the sulfated active substance solution.

[0010] In some embodiments, the lithium metal composite oxide may contain nickel, cobalt, and manganese. The manganese, cobalt, and nickel can be sequentially extracted by sequentially increasing the pH of the sulfated active material solution.

[0011] In some embodiments, the lithium metal composite oxide contains nickel, cobalt, and manganese, and the nickel, cobalt, and manganese can be extracted simultaneously.

[0012] In some embodiments, the lithium extractant may include alkylphosphinate compounds, alkylphosphonic acid compounds, or carboxylic acid compounds.

[0013] In some embodiments, the transition metal extractant and the lithium extractant can be added in a saponified state with alkali metal hydroxide.

[0014] In some embodiments, the lithium extractant can generate alkali metal sulfate and lithium sulfate from the residual solution.

[0015] In some embodiments, the alkali metal sulfate generated from the residual solution can be converted into a sulfuric acid solution and an alkali metal hydroxide.

[0016] In some embodiments, the converted alkali metal hydroxide can be recycled for saponification of the transition metal extractant and the lithium extractant.

[0017] In some embodiments, the converted sulfuric acid solution can be recycled to the step of manufacturing the sulfurized active material solution or the step of extracting a transition metal from the sulfurized active material solution.

[0018] In some embodiments, the conversion of the alkali metal sulfate generated from the residual solution into the sulfuric acid solution and the alkali metal hydroxide can include electrodialysis.

[0019] In some embodiments, the lithium extractant can be introduced into the residual solution to generate lithium sulfate.

[0020] In some embodiments, in the recovery of the lithium precursor, the generated lithium sulfate can be converted into lithium hydroxide by electrodialysis.

[0021] In some embodiments, by the electrodialysis, a sulfuric acid solution can be generated together with lithium hydroxide.

[0022] In some embodiments, the sulfuric acid solution can be recycled to the step of manufacturing the sulfurized active material solution or the step of extracting the transition metal from the sulfurized active material solution.

[0023] In the method for recovering active metal of a lithium secondary battery according to an embodiment of the present invention, sulfuric acid can be added to a lithium metal composite oxide to produce a sulfated active material solution. Transition metals can be extracted from the sulfated active material solution. Lithium hydroxide can be immediately recovered from the residual solution after the transition metals are extracted from the sulfated active material solution by electrodialysis.

[0024] In some embodiments, in the step of recovering the lithium hydroxide, lithium sulfate contained in the residual solution can be converted into lithium hydroxide by the electrodialysis.

[0025] In some embodiments, a sulfuric acid solution can be recycled to the step of producing the sulfated active material solution or the step of extracting the transition metals from the sulfated active material solution. The sulfuric acid solution can be generated from lithium sulfate by the electrodialysis.

[0026] In some embodiments, a transition metal extractant containing an alkyl phosphoric acid compound, an alkyl phosphonic acid compound, an alkyl phosphinic acid compound, or a carboxylic acid compound can be added to the sulfated active material solution to extract the transition metals.

[0027] In some embodiments, the lithium metal composite oxide contains nickel, cobalt, and manganese, and the pH of the sulfated active material solution is sequentially increased to sequentially extract manganese, cobalt, and nickel.

[0028] In some embodiments, the lithium metal composite oxide contains nickel, cobalt, and manganese, and nickel, cobalt, and manganese can be extracted simultaneously.

[0029] In some embodiments, a part of the recovered lithium hydroxide can be recycled for saponification of the transition metal extractant.

[0030] In some embodiments, hydrogen peroxide can be added together with sulfuric acid in the production of the sulfated active substance solution. [Effects of the Invention]

[0031] According to the exemplary embodiments described above, for example, after extracting nickel, manganese, and cobalt from a lithium metal composite oxide, lithium can be recovered at high concentrations using a phosphorus-containing lithium extractant to recover the lithium precursor.

[0032] In some embodiments, lithium hydroxide can be recycled and used as a neutralizing agent for nickel, manganese, and cobalt. This allows for the recovery of high concentrations of lithium precursors while substantially removing sodium (Na)-containing impurities.

[0033] In some embodiments, for example, the recovered lithium precursor, which is obtained as lithium sulfate, can be converted to lithium hydroxide by electrodialysis while the sulfuric acid solution is recycled. This reduces the amount of sulfuric acid solution introduced into the entire process, improving process yield and environmental friendliness. [Brief explanation of the drawing]

[0034] [Figure 1] Figure 1 is a schematic flowchart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment. [Figure 2] Figure 2 is a schematic flowchart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment. [Figure 3] Figure 3 is a schematic flowchart illustrating a method for recovering active metals from lithium secondary batteries using comparative examples. [Modes for carrying out the invention]

[0035] Embodiments of the present invention provide, for example, a method for recovering a precursor containing lithium and a transition metal from the positive electrode of a waste lithium secondary battery by a wet-based process.

[0036] Embodiments of the present invention will be described more specifically below with reference to the drawings. However, these embodiments are merely illustrative of the present invention and do not limit it.

[0037] As used herein, the term “precursor” is used to comprehensively refer to compounds containing a specific metal in order to provide a specific metal contained in an electrode active material.

[0038] Figure 1 is a schematic flowchart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment.

[0039] Referring to Figure 1, lithium metal composite oxides can be sulfurized by adding sulfuric acid (for example, step S10).

[0040] According to exemplary embodiments, the lithium metal composite oxide can be obtained from the positive electrode active material of a waste lithium secondary battery or a used lithium secondary battery.

[0041] The lithium secondary battery may include an electrode assembly comprising a positive electrode, a negative electrode, and a separator membrane interposed between the positive electrode and the negative electrode. The positive electrode and the negative electrode may each include a positive electrode current collector and a positive electrode active material layer and a negative electrode active material layer coated on the negative electrode current collector, respectively.

[0042] For example, the positive electrode active material contained in the positive electrode active material layer may include a lithium metal composite oxide containing lithium and a transition metal.

[0043] In some embodiments, the lithium metal composite oxide may include a compound represented by the following chemical formula 1.

[0044] [Chemical formula 1] Li x M1 a M2 b M3 c O y

[0045] In chemical formula 1, M1, M2 and M3 may be transition metals selected from Ni, Co, Mn, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, or B. <x≦1.1、2≦y≦2.02、0<a<1、0<b<1、0<c<1、0<a+b+c≦1であってもよい。

[0046] In some embodiments, the lithium metal composite oxide may be an NCM-based lithium oxide containing nickel (Ni), cobalt (Co), and manganese (Mn).

[0047] The positive electrode can be separated from the waste lithium secondary battery and recovered. The waste positive electrode includes a positive electrode current collector (e.g., aluminum (Al)) and a positive electrode active material layer, and the positive electrode active material layer may include a conductive material and a binder in addition to the positive electrode active material.

[0048] The conductive material may include, for example, carbon-based materials such as graphite, carbon black, graphene, and carbon nanotubes. The binder may include, for example, resin materials such as vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (PVDF), polyacrylonitrile, and polymethyl methacrylate.

[0049] According to some embodiments, the recovered waste cathode can be pulverized to produce a waste cathode active material mixture. This allows the waste cathode active material mixture to be produced in powder form. The waste cathode active material mixture contains, as described above, a lithium metal composite oxide powder, and may include, for example, NCM-based lithium oxide powder (e.g., Li(NCM)O2).

[0050] The waste positive electrode active material mixture may also contain a portion of the components derived from the binder or the conductive material. In one embodiment, the waste positive electrode active material mixture may be substantially composed of the lithium metal composite oxide particles.

[0051] In some embodiments, the waste cathode active material mixture can be heat-treated before being introduced into the solution reaction described later. This heat treatment removes or reduces impurities such as the conductive material and binder contained in the waste cathode active material mixture, allowing the lithium metal composite oxide to be introduced into the solution step in high purity.

[0052] The temperature of the heat treatment may be, for example, about 100 to 500°C, preferably about 350 to 450°C. Within this range, the impurities can be substantially removed, and the decomposition and damage of the lithium metal composite oxide can be prevented.

[0053] A lithium metal composite oxide prepared according to some of the embodiments described above can be subjected to a sulfation treatment by adding sulfuric acid. This makes it possible to produce a sulfated active material solution.

[0054] In some embodiments, the positive electrode can be separated from the waste lithium secondary battery, and a sulfuric acid solution can be added to the separated positive electrode. In this case, the positive electrode active material layer can be peeled off from the positive electrode current collector, and the lithium metal composite oxide can be dissolved in the sulfuric acid solution.

[0055] In some embodiments, after adding sulfuric acid, a pretreatment can be performed to remove impurities from the sulfated active material solution. For example, the impurities may include components of the current collector, conductive material, and / or binder remaining in the aforementioned waste positive electrode active material mixture. The pretreatment may include steps such as precipitation with alkali, filtration, centrifugation, and washing.

[0056] In some embodiments, hydrogen peroxide (H2O2) can be added along with the sulfuric acid solution. For example, hydrogen peroxide can act as a reducing agent and promote the extraction of transition metals, as described later.

[0057] For example, in step S20, transition metals can be extracted from the sulfated active material solution. The transition metals may include Ni, Co, and Mn, as described above.

[0058] According to exemplary embodiments, the transition metal can be extracted using a transition metal precursor (e.g., in the form of a transition metal sulfate). For example, nickel sulfate (NiSO4), cobalt sulfate (CoSO4), and manganese sulfate (MnSO4) can be produced and collected from Ni, Co, and Mn, respectively.

[0059] According to an exemplary embodiment, a transition metal extractant can be added to the sulfated active substance solution to collect the transition metal precursor. The transition metal extractant may include a phosphate compound, a phosphonic acid compound, a phosphinic acid compound, or a carboxylic acid compound.

[0060] In some embodiments, the extraction of the transition metals can be carried out by gradually increasing the pH. For example, Mn, Co, and Ni can be extracted sequentially while increasing the pH.

[0061] For example, by increasing the pH to a range of approximately 3.5 to 4.5 (e.g., approximately 4), manganese sulfate can be extracted as a manganese precursor. Then, by increasing the pH to a range of approximately 4.5 to 5.5 (e.g., approximately 5), cobalt sulfate can be extracted as a cobalt precursor. Subsequently, by increasing the pH to a range of approximately 6 to 7 (e.g., approximately pH 6.5), nickel sulfate can be extracted as a nickel precursor.

[0062] In some embodiments, multiple different transition metal extractants can be used in the extraction of the transition metals. In one embodiment, an alkyl phosphate compound can be used as a transition metal extractant for extracting Mn and Ni. For example, di-(2-ethylhexyl)phosphate (D2EHPA) can be used as the alkyl phosphate compound.

[0063] In one embodiment, an alkylphosphonic acid or alkylphosphinic acid compound can be used as a transition metal extractant for extracting Co. For example, as the alkylphosphonic acid or alkylphosphinic acid compound, 2-ethylhexyl 2-ethylhexyphosphonic acid (commercial name: PC88A) or bis(2,2,4-trimethylpentyl)phosphinic acid (commercial name: Cyanex-272) can be used.

[0064] The transition metal extractants can be used in a saponified state. For example, in the case of phosphoric acid, phosphinic acid, or phosphonic acid-based extractants, a transition metal ion (e.g., Mn) can be placed at the proton (H+) site. 2+ Co 2+ Ni 2+ ) can be substituted, allowing for the extraction of transition metals.

[0065] In this case, as the concentration of H+ in the reaction solution increases, the pH decreases, which may prevent the aforementioned stepwise extraction of transition metals. Therefore, to prevent the decrease in pH, a pre-saponified transition metal extractant can be used to suppress the decrease in pH, allowing for selective extraction of each transition metal as the pH gradually increases, as described above.

[0066] In one embodiment, the extraction of the transition metals described above can be carried out simultaneously or substantially in a single extraction step. In this case, Ni, Co, and Mn can be extracted together by adding the transition metal extractant described above.

[0067] For example, in step S30, lithium can be extracted from the residual solution from which the transition metal has been extracted as described above from the sulfated active material solution. According to an exemplary embodiment, lithium can be selectively extracted from the residual solution using a lithium extractant.

[0068] As the lithium extractant, alkylphosphinate compounds, alkylphosphonic acid compounds, or carboxylic acid compounds can be used. In one embodiment, a compound different from the transition metal extractant described above can be used as the lithium extractant. In some embodiments, for example, CYANEX936 (manufactured by Solvay) or Versatic10 (manufactured by HEXION) can be used as the lithium extractant.

[0069] In one embodiment, the same compound as the transition metal extractant described above can be used as the lithium extractant.

[0070] The residual solution may, for example, contain alkali metal ions (e.g., Na+) derived from a saponified transition metal extractant together with lithium ions. The lithium extractant is selectively reactive with lithium ions and can collect them.

[0071] In one embodiment, the residual solution may not contain divalent ions. As described above, substantially all transition metal ions can be extracted from the sulfated active material solution by a transition metal extractant. Further, as a neutralizing agent for saponification of the transition metal extractant, a monovalent alkali metal hydroxide (e.g., NaOH) is used, and divalent metal hydroxides such as Mg 2+ and Ca 2+ may not be used.

[0072] Thereby, the residual solution contains lithium and monovalent alkali metal ions, and the lithium selectivity by the lithium extractant can be improved.

[0073] In some embodiments, the lithium extractant is used in a saponified state, and a decrease in pH due to extraction of lithium can be prevented.

[0074] By selectively extracting lithium ions in a sulfuric acid-based residual solution, a preliminary lithium precursor in the form of lithium sulfate can be collected. According to an exemplary embodiment, the preliminary lithium precursor can be converted into a lithium precursor for resynthesizing a lithium metal composite oxide as a positive electrode active material (e.g., step S40).

[0075] In some embodiments, the conversion to the lithium precursor can be performed by electrodialysis (e.g., the first electrodialysis). The first electrodialysis can be performed using a bipolar electrodialysis device including a positive electrode and a negative electrode facing each other with an ion exchange membrane interposed therebetween.

[0076] For example, by the reaction of Formula 1 below, lithium ions (e.g., moving to the negative electrode) and sulfate ions (e.g., moving to the positive electrode) are separated and moved by an ion exchange membrane by hydrolysis in the bipolar electrodialysis device, and lithium hydroxide can be generated. Lithium hydroxide can be collected as the lithium precursor.

[0077] [Formula 1] Li2SO4 + 2H2O → 2LiOH + H2SO4

[0078] By selectively extracting lithium from the residual solution, alkali metal ions (e.g., sodium ions (Na+)) derived from, for example, a neutralizing agent may remain in the residual solution. For example, these alkali metal ions may remain in the form of sodium sulfate (Na2SO4).

[0079] In some embodiments, the alkali metal sulfate can be converted into a neutralizing agent (e.g., step S50). For example, by a concept substantially similar to the conversion step to the lithium precursor described above, the alkali metal sulfate can be converted to an alkali metal hydroxide (e.g., NaOH) using electrodialysis (e.g., second electrodialysis).

[0080] The method for recovering active metals according to an exemplary embodiment may further include a sulfuric acid recycling step (e.g., steps S60-1 and S60-2).

[0081] In some embodiments, as described above, lithium hydroxide can be collected from lithium sulfate as a lithium precursor by the first electrodialysis, and the separated sulfate ions can react with water to produce sulfuric acid. The sulfuric acid produced from the first electrodialysis can be recycled into the sulfation step of the lithium metal composite oxide (S10) (e.g., step S60-1).

[0082] In some embodiments, as described above, the second electrodialysis can regenerate a neutralizing agent from an alkali metal sulfate such as sodium sulfate, and the separated sulfate ions can react with water to produce sulfuric acid. The sulfuric acid produced from the second electrodialysis can be recycled into the lithium metal composite oxide sulfation step (S10) (e.g., step S60-2).

[0083] In one embodiment, the sulfuric acid produced from the first and second electrodialysis processes can be recycled to the transition metal extraction process (S20 process).

[0084] The method for recovering active metals according to an exemplary embodiment may further include a neutralizing agent recycling step (e.g., step S70).

[0085] For example, a neutralizing agent such as NaOH can be collected by the second electrodialysis. The neutralizing agent can be recycled for saponification of the transition metal extractant and / or the lithium extractant. Using the saponified transition metal extractant and lithium extractant, the extraction of transition metals and lithium can be carried out, respectively.

[0086] According to the exemplary embodiments described above, lithium ions can be concentrated to a high concentration using a lithium extractant. Furthermore, the concentrated lithium ions can be immediately converted to a lithium precursor in the form of lithium hydroxide using electrodialysis without the addition of additional formulations or reactants. This can increase the lithium recovery yield and reduce the amount of sodium-derived impurities.

[0087] Furthermore, the recycling process for sulfuric acid and neutralizing agents reduces the amount of sulfuric acid and neutralizing agents used, thereby improving process efficiency and significantly reducing environmental pollution.

[0088] Figure 2 is a schematic flowchart illustrating a method for recovering active metals from a lithium secondary battery according to an exemplary embodiment. Steps or processes that are substantially the same or similar as those described in Figure 1 are given the same or similar numbers.

[0089] Referring to Figure 2, as described above, the residual solution from which the transition metal has been extracted from the sulfated active material solution can be immediately converted to a lithium precursor (for example, step S40).

[0090] As described above, the conversion to the lithium precursor can be carried out by electrodialysis. By electrodialysis, lithium ions dissolved in the residual solution in the form of lithium sulfate can be converted to and collected as a lithium precursor in the form of lithium hydroxide.

[0091] According to exemplary embodiments, the residual solution contains lithium sulfate and does not necessarily contain alkali metal ions (e.g., Na+) or alkali metal ion compounds (e.g., Na2SO4) other than lithium. This eliminates the need to use the lithium extractant in the embodiment shown in Figure 1, and allows for immediate conversion / collection of lithium hydroxide by electrodialysis.

[0092] In some embodiments, a portion of the converted lithium hydroxide can be recycled with a neutralizing agent and used for saponification of the transition metal extractant (e.g., step S70). This eliminates the need for another neutralizing agent such as NaOH, and as described above, ensures that the residual solution is substantially free of sodium ions.

[0093] Therefore, the use of lithium extractants to separate sodium ions and the conversion process into neutralizing agents can be omitted, allowing for the collection of lithium precursors at high concentrations. This makes it possible to recycle a portion of the collected lithium precursors as a neutralizing agent for the saponification of transition metal extractants.

[0094] Figure 3 is a schematic flowchart illustrating a method for recovering active metals from lithium secondary batteries using comparative examples.

[0095] Referring to Figure 3, in the comparative example, as described in the above example, the lithium metal composite oxide can be sulfurized (for example, in step S10), and then the transition metal can be extracted / recovered, for example, in the form of sulfate, using a transition metal extractant.

[0096] The transition metal extractant is used after saponification using a neutralizing agent such as NaOH. In this case, the residual solution from which the transition metal has been extracted may contain a mixture of Na2SO4 and Li2SO4.

[0097] In comparative examples, a precipitant is used to recover the lithium precursor in the form of LiOH from the residual solution (e.g., step S30a). For example, Na2CO3 can be added as a first precipitant to convert Li2SO4 to lithium carbonate (Li2CO3). Then, for example, calcium hydroxide (Ca(OH)2) can be added as a second precipitant to convert lithium carbonate to lithium hydroxide.

[0098] According to the comparative example described above, Na ions or Na ion compounds derived from saponified transition metal extractants and precipitants may remain as impurities, reducing the purity and yield of the lithium precursor. For example, twice the equivalent amount of Na ions or Na ion compounds used in the transition metal extraction step may be generated, and the Na2CO3 used as a precipitant may further generate an equivalent amount of Na ions or Na ion compounds to the equivalent of Li ions. As a result, the amount of Na in the residual solution may exceed the amount of lithium.

[0099] In contrast, in the exemplary embodiment described above, the Na impurities originating from the precipitant can be reduced by using a lithium extractant instead of a precipitant. Furthermore, after converting the Na impurities (e.g., Na2SO4) to NaOH by a second electrodialysis, they can be recycled into the saponification step of the transition metal extractant. This reduces the amount of Na impurities generated throughout the entire process.

[0100] As illustrated in Figure 2, LiOH can also be used as a neutralizing agent for saponification of the transition metal extractant. In this case, the Na impurity can be substantially removed, and lithium can be concentrated directly from the residual solution from which the transition metal has been extracted. This can further improve the yield and purity of lithium.

[0101] Furthermore, in the above-described embodiment, sulfuric acid can be recycled and reused as a whole, further improving the environmental friendliness and productivity of the process.

[0102] The following are specific examples to aid in understanding the present invention, but these examples are merely illustrative and do not limit the scope of the appended claims. It will be obvious to those skilled in the art that various changes and modifications can be made to these examples within the scope of the present invention and the technical concept, and it is also obvious that these variations and modifications fall within the scope of the appended claims.

[0103] Example 1 As the positive electrode active material, LiNi 0.6 Co 0.2 Mn 0.2 Using O2, Mn / Ni / Co were sequentially extracted with a phosphate-based extractant saponified with NaOH, and the remaining residual solution (Li 5.9 g / L, Na 47.6 g / L, pH 6.45) was prepared (aqueous phase solution). Li was extracted and concentrated from the residual solution using a 0.8 M solution of PC88A or a 0.8 M solution of Cyanex272 (saponified with 50% NaOH, saponification degree 30%) as a lithium extractant (organic phase solution).

[0104] The volume ratio of the organic phase solution to the aqueous phase solution was maintained at 3.

[0105] The concentrations of Li and Na in the aqueous solution before extraction and the organic solution after extraction are shown in Table 1 below.

[0106] [Table 1]

[0107] Li was removed (concentrated) from the organic phase solution after extraction using a 2M sulfuric acid solution (aqueous phase solution). The volume ratio of the organic phase solution after extraction to the aqueous phase solution was maintained at 15.

[0108] The concentrations of Li and Na measured after the removal of Li are shown in Table 2 below.

[0109] [Table 2]

[0110] Referring to Tables 1 and 2, we can see that the selectivity of Li after extraction (Li / Na) has significantly increased compared to the aqueous solution before extraction. Therefore, it can be predicted that the Li selectivity will improve even further if a continuous, repeatable process including a recycling step is carried out.

[0111] Example 2 As the positive electrode active material, LiNi 0.6 Co 0.2 Mn 0.2 Ni / Co / Mn were simultaneously extracted from O2 using a sulfuric acid leachate (aqueous phase solution before extraction) with a 0.8 M (60% saponified) solution of Versatic 10 (organic phase solution) saponified with 10% LiOH as the extractant.

[0112] The volume ratio of the organic phase solution to the aqueous phase solution was maintained at 3.

[0113] The concentrations of metals in the aqueous solution before extraction and the solution after extraction are shown in Table 3 below.

[0114] [Table 3]

[0115] Referring to Table 3, the concentration of Li in the aqueous solution after extraction increased significantly, and Ni, Co, and Mn were extracted, resulting in increased Li purity and recovery rate. Furthermore, it can be predicted that the Li selectivity will improve even further if a continuous, repeatable process including a recycling step is performed.

[0116] Comparative Example As the positive electrode active material, LiNi 0.6 Co0.2 Mn 0.2 Using O2, Mn / Ni / Co were sequentially extracted with a phosphate-based extractant saponified with NaOH, and then Li was collected by evaporating and concentrating the residual solution.

[0117] The concentrations of Li and Na after evaporation and concentration are as shown in Table 4 below.

[0118] [Table 4]

[0119] Referring to Table 4, as evaporation and concentration progressed and the rate of water removal increased, Li co-precipitation occurred with Na, resulting in a decrease in the recovery rate of Li.

Claims

1. A step of adding sulfuric acid to a lithium metal composite oxide to produce a sulfated active material solution, The steps include extracting a transition metal from the aforementioned sulfated active material solution, The steps include: recovering the lithium precursor by adding a lithium extractant saponified with sodium hydroxide (NaOH) to the residual solution from which the transition metal has been extracted from the sulfated active material solution; The step includes adding the lithium extractant to generate sodium sulfate from the residual solution, converting the sodium sulfate generated from the residual solution into a sulfuric acid solution and sodium hydroxide (NaOH), and recycling the converted sodium hydroxide (NaOH) for the saponification of the lithium extractant. A method for recovering active metals from a lithium secondary battery, including electrodialysis, wherein the conversion of the sodium sulfate generated from the residual solution to the sulfuric acid solution and the sodium hydroxide (NaOH) is performed.

2. The method for recovering active metals from a lithium secondary battery according to claim 1, wherein the step of extracting the transition metals comprises adding a transition metal extractant containing an alkyl phosphate compound, an alkylphosphonic acid compound, an alkylphosphinic acid compound, or a carboxylic acid compound to the sulfated active material solution.

3. The aforementioned lithium metal composite oxide contains nickel, cobalt, and manganese. The method for recovering active metals from a lithium secondary battery according to claim 2, wherein the step of extracting the transition metals comprises sequentially increasing the pH of the sulfated active material solution and sequentially extracting manganese, cobalt, and nickel.

4. The aforementioned lithium metal composite oxide contains nickel, cobalt, and manganese. The method for recovering active metals from a lithium secondary battery according to claim 2, wherein the step of extracting the transition metals includes simultaneously extracting nickel, cobalt, and manganese.

5. The method for recovering active metals from a lithium secondary battery according to claim 2, wherein the lithium extractant comprises an alkylphosphinate compound, an alkylphosphonic acid compound, or a carboxylic acid compound.

6. The method for recovering active metals from a lithium secondary battery according to claim 5, wherein the transition metal extractant is introduced in a saponified state with an alkali metal hydroxide.

7. A method for recovering the active metal of a lithium secondary battery according to claim 6, wherein lithium sulfate is produced by removing lithium from the organic phase solution from which lithium has been extracted by adding the lithium extractant, using a sulfuric acid solution.

8. A method for recovering active metals from a lithium secondary battery according to claim 7, further comprising the step of recycling the converted sodium hydroxide (NaOH) for saponification of the transition metal extractant.

9. A method for recovering active metals from a lithium secondary battery according to claim 7, further comprising the step of recycling the converted sulfuric acid solution into a step of producing the sulfurized active material solution, or a step of extracting a transition metal from the sulfurized active material solution.

10. The lithium extractant is added to the residual solution, and lithium is extracted from the organic phase solution. Desorption is then performed using a sulfuric acid solution to produce lithium sulfate. The method for recovering the active metal of a lithium secondary battery according to claim 1, wherein the step of recovering the lithium precursor includes converting the generated lithium sulfate into lithium hydroxide by electrodialysis.

11. The method for recovering the active metal of a lithium secondary battery according to claim 10, wherein a sulfuric acid solution is produced together with lithium hydroxide by the electrodialysis.

12. A method for recovering active metals from a lithium secondary battery according to claim 11, further comprising the step of recycling the sulfuric acid solution into a step of producing the sulfurized active material solution, or a step of extracting the transition metal from the sulfurized active material solution.

13. A step of adding sulfuric acid to a lithium metal composite oxide to produce a sulfated active material solution, The steps include extracting a transition metal from the aforementioned sulfated active material solution, The step includes immediately recovering lithium hydroxide from the residual solution from which the transition metal has been extracted from the sulfated active material solution by electrodialysis, The step of extracting the transition metal includes adding a transition metal extractant that has been saponified with lithium hydroxide, wherein the transition metal extractant is neodecanoic acid. The process further includes a step in which lithium sulfate is produced by a transition metal extraction process using the introduction of the transition metal extractant, A method for recovering active metals from a lithium secondary battery, comprising converting the lithium sulfate generated from the residual solution into a sulfuric acid solution and lithium hydroxide, and recycling the converted lithium hydroxide into the saponification of neodecanoic acid.

14. The method for recovering active metals from a lithium secondary battery according to claim 13, wherein the step of recovering lithium hydroxide includes converting lithium sulfate generated from the residual solution into lithium hydroxide and sulfuric acid solution by electrodialysis.

15. A method for recovering active metals from a lithium secondary battery according to claim 14, further comprising the step of recycling the sulfuric acid solution to a step of producing the sulfurized active material solution, or a step of extracting the transition metal from the sulfurized active material solution.

16. The aforementioned lithium metal composite oxide contains nickel, cobalt, and manganese. The method for recovering active metals from a lithium secondary battery according to claim 13, wherein the step of extracting the transition metals comprises sequentially increasing the pH of the sulfated active material solution and sequentially extracting manganese, cobalt, and nickel.

17. The aforementioned lithium metal composite oxide contains nickel, cobalt, and manganese. The method for recovering active metals from a lithium secondary battery according to claim 13, wherein the step of extracting the transition metals comprises simultaneously extracting nickel, cobalt, and manganese.

18. The method for recovering the active metal of a lithium secondary battery according to any one of claims 1 or 13, wherein the step of producing the sulfated active material solution includes adding hydrogen peroxide together with sulfuric acid.

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