Regeneration solution for waste secondary battery cathode material and method for regenerating cathode material using the same

Abstract

To provide: a regeneration solution of a spent secondary battery cathode material, capable of easily obtaining a regenerated cathode material with a restored lithium composition; a method of regenerating a spent secondary battery cathode material; and a method of recycling a regeneration solution.SOLUTION: A regeneration solution of a spent secondary battery cathode material includes p-type redox molecules, a solvent, and a lithium salt. The p-type redox molecules have a reduction potential that is higher than or equal to 1.55 V and lower than or equal to 3.7 V with respect to a reduction potential of lithium (vs Li / Li+). The regeneration solution used for regenerating the cathode material is mixed with a lithium-containing reducing material to reduce redox molecules and subjected to a filtering process to be regenerated, thereby providing a recycling method capable of using the used regeneration solution as the regeneration solution again. In the recycling method, the lithium-containing reducing material may be Li2CO3, Li2O2, LiO2, LiO, Li2O, Li2S, or the like, and through this, the recycling of the regeneration solution is also possible in addition to the regeneration of the cathode material, and thus, higher economic efficiency can be ensured.SELECTED DRAWING: Figure 1

Description

Detailed Description of the Invention

[0001] 〔Technical Field〕 The present invention relates to a regeneration solution for a waste secondary battery cathode material and a recycled secondary battery using the same.

[0002] 〔Background Art〕 Lithium secondary batteries have advantages such as high energy density, light weight, high output, stable discharge characteristics, and stability over a wide range of temperatures. Recently, they have been widely used in small household appliances and precision equipment, and recently, the usage capacity of medium and large lithium secondary batteries has also increased rapidly.

[0003] With the rapid increase in the usage capacity of lithium secondary batteries, it is expected that a large amount of waste batteries will be generated recently, and the technology for recycling secondary batteries has also attracted great attention. In particular, for secondary batteries, there is an urgent need for a technology to generate a cathode material that can recover the cathode active material, which has a limited reserve and a high raw material price among the components, and can be reused.

[0004] On the other hand, among the cathode active material recycling methods that have already been utilized, the direct recycling (or cathode regeneration) method (direct recycling or cathode regeneration) can regenerate the active material through relatively less energy and a simple process while maintaining the particle shape of the waste cathode material, and has the advantage that a new cathode material can be quickly obtained from waste batteries. The direct recycling methods reported so far include a solid-phase reaction method, a hydrothermal synthesis method, a eutectic salt synthesis method, etc., but each requires precise lithium composition analysis that requires high cost, or requires a high reaction temperature of several hundred degrees and high-pressure conditions, or requires an inert atmosphere without oxygen, etc., making it difficult to realize a large-scale process, having a high cost and being difficult to commercialize.

[0005] Here, the present inventor has completed the present invention in order to solve the problems of the above-mentioned conventional cathode active material recycling methods.

[0006] 〔Summary of the Invention〕 〔Problems to be Solved by the Invention〕 The present invention has been devised to solve the above problems. By holding a cathode or a cathode active material from which all or part of lithium has been desorbed at normal temperature and normal pressure for a certain period of time, a long-term post-heat treatment process, or a regenerated cathode material in which the lithium composition can be easily restored without using a base, harmful gas, and lithium metal can be obtained. An object of the present invention is to provide a regeneration solution for a waste secondary battery cathode material.

[0007] Another object is to provide a method for regenerating a waste secondary battery cathode material by utilizing the regeneration solution, or to provide a method for recycling the regeneration solution by simply mixing the used regeneration solution with a reducing substance containing lithium after regenerating the cathode material.

[0008] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and further problems not mentioned can be clearly understood by those having ordinary knowledge in the technical field from the following description.

[0009] 〔Means for Solving the Problems〕 According to an embodiment of the present invention, there is provided a regeneration solution for a waste secondary battery cathode material, which contains a p-type redox molecule, a solvent, and a lithium salt, and the reduction potential of the p-type redox molecule is 1.55 V or more and 3.7 V or less with respect to lithium (vs Li / Li + ).

[0010] According to an embodiment of the present invention, there is provided a method for regenerating a waste secondary battery cathode material, which includes a step (S1) of dissolving a lithium salt and a p-type redox molecule in a solvent to produce a regeneration solution, a step (S2) of holding a cathode material or a desorbed cathode from which lithium has been desorbed in the solution, a step (S3) of recovering and washing the supported cathode material from the solution, and a step (S4) of drying the cathode material, and the reduction potential of the p-type redox molecule is 1.55 V or more and 3.7 V or less with respect to lithium (vs Li / Li + ).

[0011] According to one embodiment of the present invention, a regenerated cathode material is provided in the regeneration solution.

[0012] According to one embodiment of the present invention, it includes (a) a step of regenerating a waste secondary battery cathode material by utilizing the regeneration solution, and (b) a step of mixing the utilized regeneration solution with a reducing substance containing lithium, wherein the reducing substance containing lithium is Li 2 CO 3 , Li 2 O 2 , LiO 2 , LiO, Li 2 O and Li 2 S, and a recycling method of one or more regeneration solutions selected from the group consisting thereof is provided.

[0013] 〔Advantages of the Invention〕 The regeneration solution according to one embodiment of the present invention is stable without reacting in a general environment under normal temperature, normal pressure, and dry atmosphere, has high mass productivity, can recover a desired lithium composition based on high reproducibility even without information on the lithium composition of the waste cathode, and the used regeneration solution can be recycled for post-treatment, so it has the advantage of high economic efficiency.

[0014] 〔Brief Description of the Drawings〕 〔FIG. 1〕It is a schematic diagram of a regeneration solution according to one embodiment of the present invention and a cathode regeneration technique using the same.

[0015] 〔FIG. 2〕It is a diagram showing the principle of the cathode regeneration technique according to one embodiment of the present invention.

[0016] 〔FIG. 3〕In the cathode regeneration technique according to one embodiment of the present invention, it is a diagram showing an electrochemical detection of a cathode lithium recovery reaction.

[0017] 〔FIG. 4〕It is a diagram showing the recovery of the cathode material lattice constant through the cathode lithium recovery reaction according to one embodiment of the present invention.

[0018] 〔FIG. 5〕It is a diagram showing the recovery of nickel hydroxide in the cathode material through the cathode lithium recovery reaction according to one embodiment of the present invention.

[0019] Figure 6 shows the results of evaluating the electrochemical characteristics of the regenerated positive electrode according to the lithium salt concentration and the presence or absence of a p-type redox molecule.

[0020] Figure 7 shows the results of evaluating the electrochemical characteristics of the regenerated positive electrode according to the lithium composition of the waste positive electrode material.

[0021] Figure 8 shows the results of evaluating the electrochemical characteristics of the regenerated positive electrode according to the lithium composition (highly desorbed state) of the waste positive electrode material.

[0022] Figure 9 shows the results of evaluating the electrochemical characteristics of the regenerated positive electrode according to the type of solvent in dry air.

[0023] Figure 10 shows the results of evaluating the life characteristics of the positive electrode regenerated through the positive electrode lithium recovery reaction according to an embodiment of the present invention.

[0024] Figure 11 is a diagram analyzing the degree of lithium recovery according to the positive electrode regeneration reaction time and temperature.

[0025] Figure 12 is a drawing showing the results of evaluating the life characteristics of the NMC811 positive electrode regenerated through the positive electrode lithium recovery reaction according to an embodiment of the present invention.

[0026] Figure 13 shows the results of analyzing the redox voltage by applying DPPD or DBB as a p-type redox molecule.

[0027] Figure 14 shows the results of evaluating the change in Coulomb efficiency by applying DPPD or DBB as a p-type redox molecule.

[0028] Figure 15 6 shows the results of evaluating the change in Coulomb efficiency by applying it as the lithium salt of the regeneration solution.

[0029] Figure 16 is a diagram showing the recycling process schematic diagram after the use of the regeneration solution according to an embodiment of the present invention.

[0030] FIG. 17 is a diagram showing the results of verifying the recycling reaction after use of the regeneration solution.

[0031] FIG. 18 is a diagram showing the recycling cycle of the regeneration of the waste positive electrode material using the regeneration solution according to an embodiment of the present invention, the subsequent recycling of the regeneration solution, and the regeneration of the positive electrode material using the same.

[0032] FIG. 19 is a diagram showing the results of the life test of the NMC622 electrode regenerated using the recycled regeneration solution.

[0033] FIG. 20 is a diagram showing the results of evaluating the electrochemical characteristics of the NMC622 electrode regenerated using a ferrocene-based regeneration solution produced in various solvents (1,3-dioxolane (DOL), dimethyl carbonate (DMC), 2-methyltetrahydrofuran (2meTHF), acetonitrile (ACN), N,N-dimethylformamide (DMF)) and utilizing the same.

[0034] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the specific structural or functional descriptions disclosed herein are merely illustrative for the purpose of describing the embodiments, and the embodiments may be implemented in various different forms, and the present invention is not limited to the embodiments described herein. It should be understood that all modifications, equivalents or alternatives to the embodiments are included in the scope of the rights.

[0035] The terms used in the embodiments are for illustrative purposes only and are not to be construed as having an intention to limit. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including" or "having" indicate the presence of the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should not be construed as precluding the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the technical field to which this embodiment belongs. Commonly used predefined terms should be interpreted as having a meaning consistent with their meaning in the context of the related art, and should not be interpreted in an ideal or overly formal sense unless clearly defined herein.

[0037] Also, in the description with reference to the accompanying drawings, regardless of the reference numerals in the drawings, the same components are given the same reference numerals, and duplicate descriptions thereof are omitted. In the description of the embodiments, when it is determined that the specific description of the related known technology makes the gist of the embodiments needlessly ambiguous, the detailed description thereof is omitted.

[0038] According to one embodiment of the present invention, there is provided a regeneration solution for a waste secondary battery positive electrode material, which contains a p-type redox molecule, a solvent, and a lithium salt, and the reduction potential of the p-type redox molecule is 1.55 V or more and 3.7 V or less with respect to lithium (vs Li / Li + )

[0039] If the lithium ions of the lithium salt, the p-type redox molecule, and the cathode from which some lithium ions have detached are mixed together, then through a thermodynamic spontaneous reaction, the redox molecule is oxidized, the cathode active material is reduced, and lithium ions and electrons are transferred from the p-type redox molecule to the cathode active material.

[0040] Based on such a principle, lithium can be inserted into the cathode material from which lithium ions have detached in a spent secondary battery.

[0041] On the other hand, the p-type redox molecule for causing a spontaneous reaction needs to satisfy the following conditions: i) being oxidized in the neutral state and existing in the form of positive ions; ii) having an oxidation / reduction potential lower than the general charging start voltage of the cathode (in the case of NMC, 3.7 V); iii) having a reduction potential (in the case of NMC, Mn 3+ / Mn 4+ reduction potential of 1.55 V) higher than that for inducing this to prevent material deterioration due to excessive insertion of lithium.

[0042] Such a p-type redox molecule may specifically have a reduction potential of 1.55 V or more and 3.7 V or less, and more preferably 2.9 V or more and 3.6 V or less. On the other hand, when it is lower than 2.9 V, it reacts with oxygen (~2.96 V) present in the air, and its handling under the atmosphere is restricted.

[0043] As the types of p-type redox molecules that satisfy all of the above conditions (i) to (iii), molecules such as N, N’-substituted Phenazine, Phenoxazine, Phenylamine, Phenothiazine, Carbazole, Phenylamine, Thianthrene, Dibenzodioxin, Viologen, Nitroxide radical Compound, Polyaniline, Polythiophene, Polytriphenylamine, Polydiphenylamine, Ferrocene, Manganocene may be included. The molecules may be substituted with one or more of an alkyl group (-R) having 1 to 5 carbon atoms, a hydroxy group (-OH), an amine group (-NH2), a phenyl group (-Ph), a benzoate group (-BzO), an acetyl group (-CH 3 CO), a carboxyl group (-COOH), and a benzoyl group (-COC 6 H 5 ). Among them, more specifically, examples of the nitroxide radical compound include proxyl, nitroxylbenzene, nitronylnitroxyl, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), and the like.

[0044] In one embodiment of the present invention, as the type of preferred p-type redox molecule, it is oxidized in a neutral state and exists in the form of a positive ion, and undergoes an oxidation / reduction reaction at about 3.27 to 3.45 V, corresponding to 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene or manganocene.

[0045] The solvent contained in the regeneration solution according to one embodiment of the present invention may include cyclic ether solvents, linear ether solvents, carbonate (ester) solvents, acetonitrile, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAC), water (H 2 O), etc.

[0046] The solvent corresponds to a solvent that is stable at the positive electrode operating potential used, dissolves the lithium salt and the redox molecule, and does not cause side reactions.

[0047] Specific types of the cyclic ether solvents may include tetrahydropyran, dioxolane, methyldioxolane, dimethyldioxolane, vinyldioxolane, methoxydioxolane, ethylmethyldioxolane, oxane, dioxane, trioxane, tetrahydrofuran, methyltetrahydrofuran, dimethyltetrahydrofuran, dimethoxytetrahydrofuran, ethoxytetrahydrofuran, ethyltetrahydrofuran, methyltetrahydropyran, dimethyltetrahydropyran, dihydropyran, tetrahydropyran, hexamethylene oxide, furan, dihydrofuran, dimethoxybenzene, dimethyloxetane, etc.

[0048] Specific types of the linear ether solvents may include dimethyl ether, diethyl ether, ethyl methyl ether, ethyl propyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, ethyl tert-butyl ether, dimethoxymethane, trimethoxymethane, dimethoxyethane, diethoxyethane, dimethoxypropane, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, diethylene glycol tert-butyl ethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol ethyl methyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, methoxypropane, etc.

[0049] Specific types of the carbonate solvents may include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, sec-butyl acetate, t-butyl acetate, isopropyl acetate, isobutyl acetate, hexyl acetate, isoamyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl lactate, ethyl lactate, methyl phenyl lactate, methyl propionate, triacetin, ethyl acetoacetate, dimethyl adipate, benzyl benzoate, ethyl formate, etc.

[0050] The lithium salt contained in the regeneration solution according to an embodiment of the present invention is not greatly limited as long as it can be dissolved in the solvent and provide lithium ions to the cathode material from which lithium ions have been desorbed. Specifically, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF 6) Lithium bis(fluorosulfonyl)imide (LiFSI), lithium trifluoromethanesulfonate (LiTf), lithium trifluoromethanesulfonate (LiOTF), lithium tetrafluoroborate (LiBF 4 ) lithium perchlorate (LiClO 4 ) lithium hexafluoroarsenate (LiAsF 6 ) lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate) borate (LiBOB), lithium chloride (LiCl), lithium nitrate (LiNO 3 ) lithium sulfate (LiSO 4 ) lithium acetate (LiOAc) etc. may be included. More specifically, it is preferable to use a lithium salt containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF 6 ).

[0051] As the type of the positive electrode material into which lithium ions are inserted through the regeneration solution according to an embodiment of the present invention, Li[NiCoMn]O 2 , LiCoO 2 , Li[NiCoAl]O 2 , Li[NiCoMnAl]O 2 , doped-Li[NiCoMn][M]O 2 , LiMn 2 O 4 , LiFePO 4 , Li[FeMn]PO 4 , LiNi 0.5 Mn 1.5 O 4 etc. may be mentioned. Specifically, Li[NiCoMn]O 2 (NMC) with a charging start voltage of about 3.7V, LiCoO 2 (LCO) with a charging start voltage of about 3.9V, Li[NiCoAl]O 2 (NCA) with a charging start voltage of about 3.6V, LiFePO 4 (LFP) with a charging start voltage of about 3.4V etc. may be included.

[0052] On the one hand, according to an embodiment of the present invention, there are steps of dissolving a lithium salt and a p-type redox molecule in a solvent to produce a regeneration solution (S1), carrying a cathode material from which lithium has been desorbed or a desorbed cathode in the solution (S2), recovering the carried cathode material from the solution and washing it (S3), and drying the cathode material (S4). The reduction potential of the p-type redox molecule is 1.55 V or more and 3.7 V or less compared to lithium (vs Li / Li + ), and a method for regenerating a waste secondary battery cathode material is provided.

[0053] In the regeneration method, the lithium salt, p-type redox molecule, and solvent used are considered to be substantially the same as those described in the regeneration solution of the waste secondary battery cathode material described in detail above. Preferably, the lithium salt includes one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium hexafluorophosphate (LiPF 6 ), the p-type redox molecule includes one or more of 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene, and manganocene, and the solvent may include one or more of dimethoxyethane (DME) and methyltetrahydrofuran.

[0054] In the method for regenerating the waste secondary battery cathode material, as in the embodiment described in detail below, when lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 5,10-dihydro-5,10-dimethylphenazine (DMPZ) are dissolved in 1,2-dimethoxyethane (DME) to produce a regeneration solution, the following reaction occurs when the cathode material from which lithium has been desorbed is carried in the regeneration solution. Therefore, it is possible to obtain a regenerated cathode material with a restored lithium composition.

[0055] xDMPZ + xLi + + xTFSI - + Li 1-y [NiCoMn]O 2→x (DMPZ + -TFSI - ) + Li 1-y+x [NiCoMn]O 2 (0 < x ≦ y) On the other hand, the step of supporting the cathode material on the produced regeneration solution can cause a reaction at room temperature (about 25°C), normal pressure (about 1 atm), and in a dry atmosphere without separate heat treatment, or processes such as base treatment and harmful gas treatment. The supporting time may be 0.25 hours or more, and although its upper limit is not greatly restricted, for example, it may be 0.25 hours or more and 10 hours or less, or 0.5 hours or more and 5 hours or less.

[0056] The method for regenerating the cathode material according to an embodiment of the present invention does not use a separate lithium metal, and a reaction occurs easily and stably simply by supporting it on the solution without quantification for the lithium composition. There is no insertion of excessive lithium, and from the point that the lithium insertion reaction occurs until the potential of the cathode material reaches the oxidation / reduction potential of the p-type redox molecule, it has the advantages of high mass productivity and reproducibility.

[0057] The cathode material used in the method for regenerating the waste secondary battery cathode material is not greatly restricted as long as lithium is partially or completely desorbed. As an example, it may be one in which lithium has desorbed by about 5% or more of the initial lithium amount possessed by the cathode material.

[0058] In this case, the regeneration solution used with the cathode material may contain a lithium salt and a p-type redox molecule that each correspond to 1.5 times or more compared to the lithium deficiency of the cathode material. The upper limit is not greatly restricted, but it may be 20 times or less, specifically 10 times or less, and more specifically, it may be 3 times or more and 5 times or less, etc.

[0059] After performing the above-mentioned supporting step, the positive electrode material is recovered and washed. The washing process can be carried out using the same type of solvent as the solvent used in the regeneration solution above. Therefore, residual lithium salts and p-type redox molecules such as DMPZ present in the regenerated positive electrode material can be removed. After that, through a drying process, the regenerated positive electrode material can be used for electrode manufacturing.

[0060] On the other hand, according to an embodiment of the present invention, a recycling method is provided in which the regeneration solution used for the regeneration of the positive electrode material is mixed with a reducing substance containing lithium to reduce the redox molecule, and after passing through a filtration process for regeneration, it can be reused as a regeneration solution.

[0061] Here, the reducing substance containing lithium used may be Li 2 CO 3 、Li 2 O 2 、LiO 2 、LiO、Li 2 O、Li 2 S, etc. Therefore, not only the positive electrode material can be regenerated, but also the regeneration solution can be recycled, which has the advantage of ensuring higher economic efficiency.

[0062] Hereinafter, the configuration of the present invention and its effects will be described in more detail through embodiments and comparative examples. However, this embodiment is for more specifically explaining the present invention, and the scope of the present invention is not limited to this embodiment.

[0063] [Embodiment] [1. Production Example: Production of Regeneration Solution] 1. Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 5,10-dihydro-5,10-dimethylphenazine (DMPZ) were dissolved in a 1,2-dimethoxyethane (DME) solvent to produce a regeneration solution.

[0064] [2. Test Example 1: Electrochemical Detection of Positive Electrode Lithium Recovery Reaction (Figure 3)] In a three-electrode system with a NMC622 electrode charged to only 30% of its reversible capacity as the working electrode, a platinum counter electrode, and a lithium reference electrode, DMPZ was added to an electrolyte containing only LiTFSI, and the voltage change over time was observed (Figure 3).

[0065] As shown in Figure 3, immediately after adding DMPZ to the LiTFSI electrolyte to prepare a 21 mM DMPZ and 22.5 mM LiTFSI solution, the color of the solution changed rapidly to a dark green. After adding DMPZ, the voltage of the working electrode also decreased rapidly from above 3.6 V to 3.17 V and then converged.

[0066] The 3.17 V at which the open-circuit voltage of the working electrode converges is approximately the redox voltage of DMPZ. Through the color change and the converging voltage value, it was confirmed that lithium was inserted into the NMC active material by the oxidation of DMPZ, resulting in a decrease in the voltage of the working electrode.

[0067] [3. Test Example 2: Observation of the recovery of the lattice constant of the positive electrode material and the recovery of nickel oxide hydroxide in the positive electrode material through the positive electrode lithium recovery reaction (Figures 4 and 5)] (1) Recovery of the lattice constant of the positive electrode material (Figure 4) X-Ray Diffraction (XRD) analysis was performed on a new NMC622 electrode, an NMC622 electrode charged to 30% of its reversible capacity after 2 charge / discharge cycles, and an electrode regenerated by being supported in a regeneration solution of 140 mM DMPZ + LiTFSI, which is 10 times the lithium deficiency, for 2 hours in a normal-temperature argon atmosphere after charging to 30%.

[0068] As shown in Figure 4, the 003 peak of the new electrode is located at the highest angle of 18.64 degrees, moves to a smaller angle after 30% charging and a peak is found at 18.49 degrees, and after regeneration, a peak is observed at 18.65 degrees similar to the new electrode.

[0069] After the (003) peak position of the 30% charged electrode is regenerated, it is approximately restored to the new NMC622 electrode. By inserting lithium into the active material and restoring the lattice structure after the regeneration process, it can be seen that the lattice constant of the c-axis increased due to lithium desorption decreased, and the lattice constant of the a-axis that decreased increased.

[0070] (2) Recovery of the positive electrode material nickel hydroxide (Figure 5) By comparing the nickel hydroxides present in the NMC811 active material for each sample through Near-Edge X-ray Absorption Fine Structures (NEXAFS) analysis, the lithium composition differences in the active materials for each sample were analyzed.

[0071] The new pouch cell (f-NMC) and the pouch cell (d-NMC) with a 20% reduction in capacity due to deterioration were discharged before battery disassembly. The fully discharged f-NMC-d and d-NMC-d were prepared. After separating the respective positive electrodes and assembling new coin cells, they were charged to prepare the charged f-NMC-c and d-NMC-c. Furthermore, the positive electrode active material was separated from the deteriorated pouch cell and supported and regenerated for 2 hours through a regeneration solution of 140 mM DMPZ + LiTFSI, which is three times the lithium deficiency, in a normal temperature dry atmosphere, and then manufactured again with the electrode (r-NMC). The NEXAFS analysis results of these five types of samples were compared.

[0072] As shown in Figure 5, the L3 peaks of nickel in f-NCM and r-NCM at 857 eV indicated a high lithium content and low (reduced) nickel hydroxide in the positive electrode. And the L3 peaks of nickel in d-NCM-c and f-NCM-c at 858 eV indicated a high lithium content and cobalt (oxidized) nickel hydroxide in the positive electrode. Considering that the L3 peak of r-NCM is at a lower energy than that of d-NCM-d, it can be seen that lithium has sufficiently entered the positive electrode material after the regeneration process and the nickel hydroxide has been recovered.

[0073] [4. Test Example 3: Evaluation Test of the Electrochemical Characteristics of the Recycled Positive Electrode under Recycling Conditions (Figures 6 to 10)] (1) Evaluation results of the electrochemical characteristics of the regenerated positive electrode according to the lithium salt concentration and the presence or absence of p-type redox molecules (Figure 6) After charging and discharging the NMC622 coin cell twice and then charging it by 30% of the reversible capacity, the NMC622 electrode was separated. Subsequently, the positive electrode was supported and regenerated in a solution containing only LiTFSI (0.14 M LiTFSI) without DMPZ and in a regeneration solution containing DMPZ for 2 hours under normal temperature argon atmosphere. Regeneration solutions containing DMPZ in amounts corresponding to 3 times (0.042 M DMPZ + 0.042 M LiTFSI) and 1.5 times, respectively, of the lithium deficiency in the positive electrode were used.

[0074] Each regenerated electrode treated under the above three conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, Celgard was used as the separator, and a CR2032 type battery was manufactured using a 1 M LiPF6 EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of a charging upper voltage of 4.3 V and a discharging lower voltage of 2.5 V at a normal temperature of +30 °C to evaluate the change in Coulombic efficiency depending on the presence or absence of recycling.

[0075] As shown in Figure 6, after supporting the electrode in a solution without DMPZ, the initial charge capacity decreased to 130 mAh g -1 at the time of reassembly (indicating no lithium insertion), but when the electrode was supported in a regeneration solution containing DMPZ, when the amount of DMPZ was 3 times that of the lithium deficiency, the charge capacity recovered by 100.5%, and when it was 1.5 times, it recovered by 100.4%. It was confirmed that when the amount of DMPZ was large compared to the lithium deficiency, the charge capacity recovered close to 100% regardless of the amount of DMPZ compared to the lithium deficiency.

[0076] (1) Evaluation results of the electrochemical characteristics of the regenerated positive electrode according to the heterogeneous lithium composition of the waste positive electrode material (Figure 7) After each of the three NMC622 coin cells was charged / discharged twice, the NMC electrodes were separated after charging by 15%, 30%, and 45% of the reversible capacity. After separating the NMC electrodes, the three electrodes were regenerated by being supported in a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) in a normal-temperature argon atmosphere for 1 hour. A regeneration solution in an amount corresponding to 10 times the sum of the lithium deficiencies of the three positive electrodes was used.

[0077] Each of the regenerated electrodes processed under the above three conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, a Celgard was used as the separator, and 1 M LiPF 6 A CR2032-type battery was manufactured using an EC / DEC electrolyte. The battery was charged / discharged at a current density of 0.1 C in the range of a charging upper voltage of 4.3 V and a discharging lower voltage of 2.5 V at a normal temperature of +30 °C to evaluate the change in Coulombic efficiency depending on the presence or absence of recycling.

[0078] As shown in Fig. 7, after the electrodes were regenerated by being simultaneously supported in the regeneration solution, the electrodes charged by 15%, 30%, and 45% of the reversible capacity recovered their initial charging capacities after reassembly at 103%, 106%, and 104% respectively. As a result, it was confirmed that the regeneration solution can regenerate waste positive electrode materials having a heterogeneous lithium composition.

[0079] (3) Results of evaluating the electrochemical characteristics of the regenerated positive electrode according to the lithium composition of the waste positive electrode material (highly desorbed state) (Fig. 8) After the NMC622 coin cell was charged / discharged twice, the NMC electrode was separated after charging by 90% of the reversible capacity. After separating the NMC electrode, a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) in an amount corresponding to 10 times the lithium deficiency of the waste positive electrode was used for regeneration in a normal-temperature argon atmosphere for 2 hours.

[0080] The regenerated electrode processed under the above conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, a Celgard was used as the separator, and 1 M LiPF 6A CR2032 type battery was manufactured using an EC / DEC electrolyte. The battery was charged / discharged at a current density of 0.1C in the range of a charging upper voltage of 4.3V and a discharging lower voltage of 2.5V at a normal temperature of +30°C, and the change in Coulomb efficiency depending on the presence or absence of recycling was evaluated.

[0081] As shown in Fig. 8, after the electrode was supported on the regeneration solution and subjected to regeneration treatment, it was confirmed that even when the lithium deficiency of the waste positive electrode was large, it could be successfully regenerated through the fact that the electrode charged to 90% of the reversible capacity showed the initial charging capacity after reassembling 103%.

[0082] (4) Evaluation results of the electrochemical characteristics of the regenerated positive electrode according to the type of solvent in dry air (Fig. 9) After the NMC622 coin cell was charged / discharged twice and then charged to 30% of the reversible capacity, the NMC electrode was separated. After separating the NMC electrode, it was regenerated by supporting it on a regeneration solution using DME or 2-meTHF solvent under normal temperature dry air conditions for 2 hours. A regeneration solution (0.14M DMPZ + 0.14M LiTFSI) corresponding to 10 times the amount of the lithium deficiency of the positive electrode was used respectively.

[0083] Each regenerated electrode treated under the above two solvent conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16mm and used as the negative electrode, and Celgard was used as the separator, 1M LiPF 6 A CR2032 type battery was manufactured using an EC / DEC electrolyte. The battery was charged / discharged at a current density of 0.1C in the range of a charging upper voltage of 4.3V and a discharging lower voltage of 2.5V at a normal temperature of +30°C, and the change in Coulomb efficiency depending on the presence or absence of recycling was evaluated.

[0084] The electrodes regenerated with different solvents of DME and 2-meTHF in dry air showed initial Coulomb efficiencies of 100% and 103% respectively. It was also confirmed that the active material could be successfully regenerated even when regeneration was carried out in a state of being exposed to dry air or when a regeneration solution using other solvents was used.

[0085] (5) Recycling Positive Electrode Life Characteristic Evaluation (Figure 10) After charging and discharging the NMC622 coin cell twice and then charging it to 30% of the reversible capacity, the NMC electrode was separated and supported in a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) using 2-meTHF solvent for 2 hours under normal temperature and dry air conditions for regeneration. The said regeneration solution was used in an amount corresponding to 10 times that of the lithium deficiency of the positive electrode. Furthermore, in order to observe the presence or absence of electrode deterioration during the regeneration process, a sample (DMPZ-free) in which the electrode charged under the same conditions using a 0.14 M LiTFSI solution without DMPZ was supported was prepared.

[0086] Each electrode treated under the said conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, Celgard was used as the separator, and 1M LiPF 6 A CR2032 type battery was manufactured using an EC / DEC electrolyte. The said battery was charged at a normal temperature of +30°C with an upper charging voltage of 4.3 V and discharged at a lower discharge voltage of 2.5 V at a current density of 0.1 C for 3 cycles, and then charged and discharged at a current density of 0.5 C to evaluate the change in life characteristics depending on the presence or absence of recycling.

[0087] As shown in Figure 10, it was confirmed that the electrode regenerated using 2-meTHF solvent under dry air conditions retained 85.9% of its capacity after 200 cycles, with no significant difference from the capacity retention rate of 86.3% of the electrode treated without DMPZ. Therefore, it was confirmed that the regeneration treatment did not have an adverse effect on the life of the positive electrode.

[0088] [5. Test Example 4: Analysis of Lithium Recovery Degree by Positive Electrode Regeneration Reaction Time (Figure 11)] After charging and discharging the NMC622 coin cell twice and then charging it to 30% of the reversible capacity, the NMC electrode was separated and the regeneration degree depending on the loading time was compared by varying the loading time in a DME-based 0.042 M DMPZ + 0.042 M LiTFSI regeneration solution under normal temperature and argon atmosphere. For the electrode loaded for 0.25 hours, the regeneration degree depending on temperature was compared by treating it at two different temperatures, normal temperature and 50°C.

[0089] Using the electrodes processed under the respective time conditions as the positive electrode, punching a lithium metal chip into a 16 mm diameter for use as the negative electrode, using a cell guard as the separator, and 1M LiPF 6 A CR2032 type battery was manufactured using an EC / DEC electrolyte. The battery was charged / discharged at a current density of 0.1C in the range of a charging upper voltage of 4.3V and a discharging lower voltage of 2.5V at a normal temperature of +30°C.

[0090] As shown in Fig. 11, the Coulombic efficiency converged to 100% while the time for supporting the electrode in the solution increased from 0.25 hours to 2 hours, and it was saturated around 1 hour. Also, when the active material was regenerated at 50°C, it was confirmed that the temperature could be raised through the recovery of the charge capacity that was nearly saturated at 100% in 15 minutes, enabling more rapid regeneration.

[0091] [6. Test Example 5: Results of Rate Capability and Life Characteristics Evaluation According to the Type of Positive Electrode Material (Fig. 12)] (i) LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) pristine positive electrode powder, (ii) positive electrode powder (degraded) recovered from a pouch cell with a 20% reduction in capacity, (iii) powder obtained by regenerating the corresponding positive electrode by supporting it in a regeneration solution (0.14M DMPZ + 0.14M LiTFSI) three times the amount of lithium deficiency in normal temperature dry air for 2 hours and mixing it with NMP, PVDF, and Super P to manufacture three types of NMC811 positive electrodes.

[0092] Punching the NMC811 electrode into a 11.3 mm diameter for use as the positive electrode, punching a lithium metal chip into 16 mm for use as the negative electrode, using a cell guard as the separator, and 1M LiPF 6A CR2032 type battery was manufactured using an EC / DEC electrolyte. The battery was charged at a normal temperature of +30°C in the range of a charging upper voltage of 4.3 V and a discharging lower voltage of 3.0 V at a current density of 0.1 C, and after 3 cycles, charging / discharging was performed at a current density of 0.5 C, and the life characteristics with or without recycling were evaluated. Also, in order to confirm the difference in the rate-determining characteristics with or without recycling, the rate-determining characteristics were evaluated while changing the rate-determining step in the order of 0.1 C, 0.5 C, 1 C, 2 C, 3 C, and then again 0.5 C.

[0093] As shown in FIG. 12, the deteriorated NMC811 positive electrode showed a capacity of 159.1 mAh g, which was 18.1% less in the first charge compared to the new positive electrode, and after regeneration, the first charge capacity recovered to 202.3 mAh g. -1 and after regeneration, the first charge capacity recovered to 202.3 mAh g. -1 There was no difference in the capacity retention rate between the new positive electrode and the regenerated positive electrode after charging / discharging during 150 cycles.

[0094] Also, it was confirmed that the same rate-determining characteristics were shown under the conditions of a current density of 0.1 C to 3 C regardless of the presence or absence of the recycling process, and the waste positive electrode regeneration process was applicable to NMC811 regardless of the type of the positive electrode material and did not affect the rate-determining characteristics of the active material.

[0095] [7. Test Example 6: Test according to p-type redox molecular species (FIGS. 13 and 14)] (1) Redox voltage analysis by applying DPPD or DBB (FIG. 13) The cyclic voltammetry (CV voltammetry) test of a regeneration solution with 21 mM of N,N'-diphenyl-p-phenylenediamine (DPPD) or 1,4-di-tert-butyl-2,5-dimethoxybenzene (DBB) as the p-type redox molecule and 21 mM of LiTFSI as the lithium salt was used to analyze the redox voltage of each redox molecule.

[0096] A 16π-diameter stainless steel plate was used as the working electrode, a lithium metal chip punched to have a diameter of 16 mm was used as the negative electrode, and 30 mL of a regeneration solution was introduced as the electrolyte into a coin cell with a cell guard as the separator membrane. Then, the voltage was scanned at a rate of 1 mV s -1 The voltage was scanned at a rate of 1 mV s.

[0097] As shown in Fig. 13, DPPD has a sufficiently low reduction potential by showing a reduction potential of 3.45 V and was utilized as the p-type redox molecule of the recycling solution. However, in the case of DBB, it was confirmed that it is not suitable for use as the p-type redox molecule of the regeneration solution because it has a reduction potential of 4.25 V, which is higher than 3.6 V, the charge start voltage of NMC.

[0098] (2) Evaluation of the change in Coulombic efficiency by applying DPPD or DBB (Fig. 14) After charging / discharging the NMC622 coin cell twice and then charging it by 30% of the reversible capacity, the NMC electrode was separated. After separating the NMC electrode, the positive electrode was supported and regenerated in a regeneration solution utilizing DPPD (0.14 M DPPD + 0.14 M LiTFSI) or DBB (0.14 M DBB + 0.14 M LiTFSI) under normal temperature argon atmosphere for 0.25 hours. A regeneration solution in an amount corresponding to 10 times the lithium deficiency of the positive electrode was used.

[0099] Each electrode treated under the above conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, and the cell guard was used as the separator membrane. 1 M LiPF 6 An EC / DEC electrolyte was used to manufacture a CR2032 type battery. The battery was charged / discharged at a current density of 0.1 C in the range of a charging upper voltage of 4.3 V and a discharging lower voltage of 2.5 V at a normal temperature of +30°C, and the change in Coulombic efficiency with or without recycling was evaluated.

[0100] As shown in FIG. 14, after supporting the electrode on the solution utilizing DPPD, it showed the initial Coulombic efficiency recovered by only 98.3% (upper graph in FIG. 14). However, when the electrode was supported on the regenerated solution utilizing DBB, it showed only 81.3% of the initial charge capacity (lower graph in FIG. 14). Thereby, it was confirmed that DPPD having an appropriate reduction potential (3.45 V) can regenerate the positive electrode, while DBB having a reduction potential (4.24 V) that is not low enough does not regenerate the active material.

[0101] [8. Test Example 7: Positive Electrode Regeneration Test According to Lithium Salt Type (FIG. 15)] After charging / discharging the NMC622 coin cell twice and then charging it by 30% of the reversible capacity, the NMC electrode was separated. After separating the NMC electrode, 6 and DMPZ were utilized to support and regenerate the positive electrode in a normal temperature argon atmosphere for 0.25 hours. A regenerated solution (0.14 M DMPZ + 0.14 M LiPF 6 ) corresponding to 10 times the lithium deficiency of the positive electrode was used.

[0102] The regenerated electrode treated under the above conditions was used as the positive electrode, a lithium metal chip was punched to a diameter of 16 mm and used as the negative electrode, a cell guard was used as the separator, and a CR2032 type battery was manufactured using a 1M LiPF 6 EC / DEC electrolyte. The battery was charged / discharged at a current density of 0.1C in the range of a charging upper voltage of 4.3V and a discharging lower voltage of 2.5V at a normal temperature of +30°C, and the change in Coulombic efficiency depending on the presence or absence of recycling was evaluated.

[0103] As shown in FIG. 15, even when using a regenerated solution utilizing LiPF 6 , it was confirmed that the NMC active material can be successfully regenerated even when using other lithium salts than LiTFSI through the fact that the initial charge capacity after reassembly showed 98.2%.

[0104] [9. Test Example 8: Verification Test of Recycling Reaction after Use of Regenerated Solution (FIG. 17)] New regeneration solution via UV-vis absorbance spectroscopy, the solution used to regenerate the electrode, and three types of solutions restored by adding Li 2 O 2 were analyzed.

[0105] The peak near 339 nm indicates unoxidized neutral DMPZ, and the peaks near 400 - 500 nm and 600 - 750 nm indicate oxidized DMPZ+. In Figure 17, after using the new regeneration solution where only neutral DMPZ existed, the DMPZ+ peak was shown, and after restoration through Li 2 O 2 the DMPZ+ peak disappeared again, indicating that the DMPZ oxidized during the regeneration process was reduced back to neutral DMPZ during the restoration process.

[0106] [10. Test Example 9: Life test of NMC622 electrode regenerated through recycling of regeneration solution (Figure 19)] The electrode that was delithiated by only 30% of the reversible capacity was regenerated (RY-NCM) by being supported on the recycled regeneration solution for 2 hours under an argon atmosphere. The recycled regeneration solution was obtained by mixing Li 2 O 2 with the used regeneration solution. Furthermore, to observe the presence or absence of electrode degradation in the regeneration solution, a sample (DMPZ-free) was prepared by supporting the electrode charged to 30% under the same conditions in a 0.14 M LiTFSI solution without DMPZ.

[0107] To prepare the used regeneration solution, after charging / discharging the NMC622 coin cell twice and then charging it by only 30% of the reversible capacity, the NMC electrode was separated. After regenerating the electrode using a regeneration solution containing an amount of DMPZ and LiTFSI corresponding to 1.5 times the lithium deficiency of the positive electrode detached after separating the NMC electrode, the used regeneration solution was recovered for the recycling process.

[0108] Using the electrode regenerated under the above conditions as the positive electrode, punching a lithium metal chip into 16 mm to use as the negative electrode, using a cell guard as the separator, and 1M LiPF 6 A CR2032 type battery was manufactured using an EC / DEC electrolyte. After the battery was charged at a normal temperature of +30 °C in the upper voltage range of 4.3 V and discharged in the lower voltage range of 2.5 V at a current density of 0.1C for 2 cycles, charge / discharge was performed at a current density of 0.5C to evaluate the life characteristics depending on the presence or absence of recycling of the solution.

[0109] As shown in Fig. 19, even when the electrode was regenerated using the restored regeneration solution, the initial charge capacity after assembly only recovered by 102.7%, and after 200 cycles, it showed a capacity retention rate of 85.3%. It was confirmed that regeneration using the recycled regeneration solution had no adverse effect on the life.

[0110] [11. Test Example 10: Evaluation of the Electrochemical Characteristics of the Regenerated Positive Electrode by Solvent (Fig. 20)] (1) Manufacture of the regenerated NMC positive electrode The NMC622 coin cell was charged / discharged twice and then charged by 30% of the reversible capacity, and then the NMC electrode was separated. Then, it was regenerated by being supported in a regeneration solution (0.1M ferrocene + 0.1M LiTFSI) in an argon atmosphere at 30 °C for 1 hour. As the solvent of the regeneration solution, dioxolane (1,3-dioxolane), dimethyl carbonate, 2-methyltetrahydrofuran, acetonitrile, and N,N-dimethylformamide were used respectively. Here, a regeneration solution containing an amount of DMPZ and LiTFSI corresponding to 10 times that of the lithium deficiency in the NMC electrode active material was used.

[0111] (2) Evaluation of the change in Coulombic efficiency Using the electrode regenerated under the electrical angle solvent conditions as the positive electrode, punching a lithium metal chip into a diameter of 16 mm to use as the negative electrode, using a cell guard 2320 as the separator, and 1M LiPF 6A CR2032 type battery was manufactured using an EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of a charging upper voltage of 4.3 V and a discharging lower voltage of 2.5 V at a normal temperature of +30 °C, and the change in Coulombic efficiency with or without recycling was evaluated, and the results are shown in Fig. 20.

[0112] (3) After reassembling the regenerated electrode, the initial charge capacity was evaluated The electrodes regenerated using the regeneration solutions of dioxolane (1,3 - dioxolane), dimethyl carbonate, 2 - methyltetrahydrofuran, acetonitrile, and N,N - dimethylformamide showed initial charge capacities of 106.43%, 108.80%, 105.36%, 101.00%, and 107.20% respectively after reassembly, and it was confirmed that NMC electrodes can be regenerated using various organic solvents.

[0113] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to the above - described embodiments, and those with ordinary knowledge in the technical field can apply various technical modifications and deformations based on the above. For example, the described technology can be executed in an order different from the described method, and / or the described components can be combined or assembled in a form different from the described method, or replaced by other components or equivalents, and appropriate results can still be achieved.

[0114] Therefore, other realizations, other embodiments, and those equivalent to the scope of the claims also fall within the scope of the claims described below.

Brief Description of the Drawings

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Claims

1. comprising a p-type redox molecule, a solvent and a lithium salt; The reduction potential of the p-type redox molecule is expressed as a ratio of the reduction potential of lithium (vs Li / Li ＋ ) A regenerating solution for used secondary battery positive electrode material, wherein the voltage is 1.55V or more and 3.7V or less.

2. The reduction potential of the p-type redox molecule is expressed as a ratio of the reduction potential of lithium (vs Li / Li ＋ 2.9V or more and 3.6V or less.

3. The p-type redox molecules include N,N'-substituted phenazine, phenoxazine, phenylamine, phenothiazine, carbazole, phenylamine, thianthrene, dibenzodioxin, viologen, and nitroxide radical compounds. Radical Compound, polyaniline, polythiophene, polytriphenylamine, polydiphenylamine, ferrocene, manganocene, and one or more molecules selected from the group consisting of; The molecule contains an alkyl group (-R) having 1 to 5 carbon atoms, a hydroxyl group (-OH), an amine group (-NH ２ ), phenyl group (-Ph), benzoate group (-BzO), acetyl group (-CH ３ CO), carboxyl group (-COOH) and benzoyl group (-COC ６ H ５ 2. The regeneration solution of waste secondary battery positive electrode material according to claim 1, wherein the regeneration solution is replaced with one or more of the following:

4. The solvents include cyclic ether solvents, linear ether solvents, carbonate (ester) solvents, acetonitrile, dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAC), and water (H ２ The regeneration solution for used secondary battery positive electrode materials according to claim 1, comprising at least one selected from the group consisting of:

5. The regeneration solution for used secondary battery positive electrode material according to claim 4, wherein the cyclic ether-based solvent is selected from the group consisting of tetrahydropyran, dioxolane, methyl dioxolane, dimethyl dioxolane, vinyl dioxolane, methoxy dioxolane, ethyl methyl dioxolane, oxane, dioxane, trioxane, tetrahydrofuran, methyl tetrahydrofuran, dimethyl tetrahydrofuran, dimethoxy tetrahydrofuran, ethoxy tetrahydrofuran, ethyl tetrahydrofuran, methyl tetrahydropyran, dimethyl tetrahydropyran, dihydropyran, tetrahydropyran, hexamethylene oxide, furan, dihydrofuran, dimethoxybenzene and dimethyl oxetane.

6. The regeneration solution for used secondary battery positive electrode material according to claim 4, wherein the linear ether-based solvent is selected from the group consisting of dimethyl ether, diethyl ether, ethyl methyl ether, ethyl propyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, diisobutyl ether, ethyl tert-butyl ether, dimethoxymethane, trimethoxymethane, dimethoxyethane, diethoxyethane, dimethoxypropane, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol diethyl ether, diethylene glycol tert-butyl ethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol ethyl methyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, and methoxypropane.

7. The regeneration solution for used secondary battery positive electrode material according to claim 4, wherein the carbonate-based solvent is selected from the group consisting of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, sec-butyl acetate, t-butyl acetate, isopropyl acetate, isobutyl acetate, hexyl acetate, isoamyl acetate, methyl butyric acid, ethyl butyric acid, propyl butyric acid, methyl lactate, ethyl lactate, phenyl methyl lactate, methyl propionate, triacetin, ethyl acetoacetate, dimethyl adipate, benzyl benzoate, and ethyl formate.

8. The lithium salts include lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium hexafluorophosphate (LiPF ６ ), lithium bisfluorosulfonylimide (LiFSI), lithium trifluoromethanesulfonate (LiTf), lithium trifluoromethanesulfonate (LiOTF), lithium tetrafluoroborate (LiBF ４ ), lithium perchlorate (LiClO ４ ), lithium hexafluoroarsenate (LiAsF ６ ), lithium difluorooxalatoborate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium chloride (LiCl), lithium nitrate (LiNO ３ ), lithium sulfate (LiSO ４ 2. The regeneration solution for used secondary battery positive electrode material according to claim 1, comprising at least one selected from the group consisting of lithium acetate (LiOAc).

9. The positive electrode material is Li[NiCoMn]O ２ , LiCoO ２ , Li[NiCoAl]O ２ , Li[NiCoMnAl]O ２ , doped-Li[NiCoMn][M]O ２ , LiMn ２ O ４ , LiFePO ４ , Li[FeMn]PO ４ , and LiNi ０．５ Mn １．５ O ４ The regeneration solution for used secondary battery positive electrode material according to claim 1, comprising one or more selected from the group consisting of:

10. A step (S1) of dissolving a lithium salt and a p-type redox molecule in a solvent to prepare a regenerated solution; A step (S2) of supporting the positive electrode material from which lithium has been desorbed in the solution; A step (S3) of recovering the supported cathode material from the solution and washing it; A step (S4) of drying the positive electrode material; Including, The reduction potential of the p-type redox molecule is relative to lithium (vs Li / Li ＋ ) A method for regenerating a positive electrode material of a used secondary battery, wherein the voltage is 1.55 V or more and 3.7 V or less.

11. The lithium salts are lithium bistrifluoromethanesulfonylimide (LiTFSI) and lithium hexafluorophosphate (LiPF ６ ) The p-type redox molecule includes one or more of 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene, and manganocene; The method for regenerating used secondary battery positive electrode materials according to claim 10, wherein the solvent includes one or more of dimethoxyethane (DME), 1,3-dioxolane (DOL), 2-methylhydrofuran (2meTHF), acetonitrile (ACN), and N,N-dimethylformamide (DMF).

12. The method for regenerating a used secondary battery positive electrode material according to claim 10, wherein the step S2 includes supporting the positive electrode material at room temperature and normal pressure for 0.25 hours or more.

13. The method for regenerating a used secondary battery positive electrode material according to claim 10, wherein the positive electrode material from which lithium has been deintercalated is one from which 5% or more of the initial amount of lithium has been deintercalated.

14. The method for regenerating a used secondary battery positive electrode material according to claim 10, wherein the regenerating solution contains a lithium salt and a p-type redox molecule in an amount 1.5 times or more of the lithium deficiency of the positive electrode material.

15. The method for regenerating a used secondary battery positive electrode material according to claim 10, wherein the washing in the step S3 is performed using the same solvent as the solvent of the regeneration solution.

16. A positive electrode material regenerated with the regenerating solution according to claim 1.

17. (a) regenerating a used secondary battery positive electrode material by utilizing the regenerating solution described in claim 1; (b) mixing the utilized regenerant solution with a reductant comprising lithium; Including, The lithium-containing reducing substance is Li ２ CO ３ , Li ２ O ２ , LiO ２ , LiO, Li ２ O, and Li ２ A method for reusing a regenerated solution, comprising:

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