Cathode material regeneration solution for waste secondary battery and cathode material regeneration method using same

Abstract

The present invention relates to a regeneration solution of a waste secondary battery cathode material, a method for regenerating a cathode material and a regenerated cathode material, using same, and a method for recycling the regeneration solution, the regeneration solution comprising p-type redox molecules, a solvent, and a lithium salt, wherein the reduction potential of the p-type redox molecules is 1.55-3.7 V versus lithium (vs Li / Li+).

Description

A solution for regenerating anode materials from waste secondary batteries and a method for regenerating anode materials using the same

[0001] The present invention relates to a solution for regenerating a cathode material of a waste secondary battery and a recycled secondary battery using the same.

[0002] Lithium secondary batteries have many advantages, such as high energy density, light weight, high output while maintaining stable discharge characteristics, and stability over a wide range of temperatures. Therefore, they are widely used in small home appliances and precision devices today, and their use in medium- to large-sized lithium secondary batteries is also rapidly increasing.

[0003] With the rapidly increasing use of lithium secondary batteries, a large volume of waste batteries is expected to be generated in the future. Recycling technologies for these batteries are also attracting significant attention. In particular, there is an urgent need for technologies that can recover cathode active materials, a component of secondary batteries whose reserves are limited and raw materials are expensive, and turn them into reusable cathode materials.

[0004] Meanwhile, among the existing methods for recycling positive electrode active materials, the direct recycling (or cathode regeneration) method has the advantage of being able to quickly obtain new positive electrode materials from spent batteries by regenerating the active material through a relatively low energy and simple process while maintaining the particle shape of the waste positive electrode material. The direct recycling methods reported so far include solid-state reaction method, hydrothermal synthesis method, and eutectic salt synthesis method, but each of them requires expensive and precise analysis of lithium composition, requires high reaction temperatures of hundreds of degrees and high pressure conditions, or requires an inert atmosphere without oxygen, making large-scale processes difficult and expensive, which is an obstacle to commercialization.

[0005] Accordingly, the inventor of the present invention has completed the present invention in order to solve the problems of the existing positive electrode active material recycling method as described above.

[0006] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a regeneration solution for a waste secondary battery cathode material, which can easily obtain a regenerated cathode material with recovered lithium composition by supporting a cathode or cathode active material from which lithium has been completely or partially desorbed at room temperature and pressure for a certain period of time, without a long-term post-heat treatment process or the use of bases, toxic gases, or lithium metal.

[0007] In addition, the present invention aims to provide a method for regenerating a waste secondary battery cathode material by utilizing the regeneration solution, or to provide a method for recycling a regeneration solution by simply mixing the used regeneration solution with a reducing material including lithium after regeneration of the cathode material.

[0008]

[0009] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the relevant technical field from the description below.

[0010] According to one embodiment of the present invention, a p-type redox molecule, a solvent and a lithium salt are included,

[0011] The reduction potential of the above p-type redox molecule is vs. Li / Li + ) A regeneration solution for a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less is provided.

[0012]

[0013] According to one embodiment of the present invention, there is provided a step (S1) of preparing a regeneration solution by dissolving a lithium salt and a p-type redox molecule in a solvent;

[0014] A step (S2) of supporting a cathode material or a cathode from which lithium has been desorbed in the above solution;

[0015] A step (S3) of recovering and washing the loaded cathode material from the solution; and

[0016] Step of drying the above cathode material (S4);

[0017] Includes,

[0018] The reduction potential of the above p-type redox molecule is vs. Li / Li + ) A method for regenerating a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less is provided.

[0019]

[0020] According to one embodiment of the present invention, a cathode material regenerated with the regeneration solution is provided.

[0021]

[0022] According to one embodiment of the present invention, there is provided a method for regenerating a waste secondary battery cathode material, comprising: (a) regenerating a waste secondary battery cathode material using the regeneration solution described in claim 1; and

[0023] (b) a step of mixing the utilized regeneration solution with a reducing material including lithium;

[0024] Includes,

[0025] A method for recycling a regeneration solution is provided, wherein the reducing material including lithium is at least one selected from the group consisting of Li2CO3, Li2O2, LiO2, LiO, Li2O and Li2S.

[0026] A regeneration solution according to one embodiment of the present invention has the advantage of being highly mass-producible because it is stable without reactivity in a general environment under room temperature, pressure, and dry air, and can recover a desired amount of lithium composition based on high reproducibility even without information on the lithium composition of a spent positive electrode, and can be reused after post-processing the used regeneration solution, so it is highly economical.

[0027] Figure 1 is a schematic diagram of a regeneration solution and a cathode regeneration technology using the same according to one embodiment of the present invention.

[0028] Figure 2 is a drawing showing the principle of a positive electrode regeneration technology according to one embodiment of the present invention.

[0029] FIG. 3 is a diagram showing electrochemical detection of a positive electrode lithium recovery reaction in a positive electrode regeneration technology according to one embodiment of the present invention.

[0030] FIG. 4 is a diagram showing the recovery of the cathode material lattice constant through a cathode lithium recovery reaction according to one embodiment of the present invention.

[0031] FIG. 5 is a diagram showing the recovery of the oxidation number of positive electrode nickel through a positive electrode lithium recovery reaction according to one embodiment of the present invention.

[0032] Figure 6 is a diagram showing the results of evaluating the electrochemical characteristics of a regenerative cathode according to the lithium salt concentration and the presence or absence of p-type redox molecules.

[0033] Figure 7 is a diagram showing the results of evaluating the electrochemical characteristics of a regenerated cathode according to the composition of lithium in the waste cathode material.

[0034] Figure 8 is a diagram showing the results of evaluating the electrochemical characteristics of a regenerated cathode according to the lithium composition (highly desorbed state) of the waste cathode material.

[0035] Figure 9 is a diagram showing the results of evaluating the electrochemical characteristics of a regenerative anode according to the type of solvent under dry air.

[0036] FIG. 10 is a diagram showing the results of evaluating the life characteristics of a positive electrode regenerated through a positive electrode lithium recovery reaction according to one embodiment of the present invention.

[0037] Figure 11 is a diagram analyzing the degree of lithium recovery according to the positive electrode regeneration reaction time and temperature.

[0038] FIG. 12 is a diagram showing the results of evaluating the life characteristics of an NMC 811 cathode regenerated through a cathode lithium recovery reaction according to one embodiment of the present invention.

[0039] Figure 13 is a diagram showing the results of analyzing redox voltage by applying DPPD or DBB as a p-type redox molecule.

[0040] Figure 14 is a diagram showing the results of evaluating the change in Coulomb efficiency by applying DPPD or DBB as a p-type redox molecule.

[0041] Figure 15 is a diagram showing the results of evaluating the change in coulombic efficiency by applying LiPF6 as a lithium salt in a regeneration solution.

[0042] Figure 16 is a schematic diagram showing a recycling process after use of a regeneration solution according to one embodiment of the present invention.

[0043] Figure 17 is a drawing showing the results of verifying the recycling reaction after use of the regeneration solution.

[0044] FIG. 18 is a diagram showing a cycle of regeneration of waste cathode material using a regeneration solution according to one embodiment of the present invention, subsequent recycling of the regeneration solution, and regeneration of cathode material using the same.

[0045] Figure 19 is a diagram showing the results of a life test of an NMC 622 electrode regenerated using a recycled regeneration solution.

[0046] Figure 20 is a diagram showing the results of evaluating the electrochemical characteristics of NMC 622 electrodes prepared using ferrocene-based regeneration solutions prepared in various solvents (dioxolane (1,3-dioxolane; DOL), dimethyl carbonate (DMC), 2-methylhydrofuran (2meTHF), acetonitrile (ACN), and dimethylformamide (N,N-dimethylformamide; DMF)) and regenerated using the solutions.

[0047] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, the embodiments may be modified in various ways, and the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or alternatives to the embodiments are included within the scope of the patent application.

[0048] The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0049] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments pertain. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0050] In addition, when describing with reference to the attached drawings, identical components will be assigned the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. When describing embodiments, if a detailed description of a related known technology is judged to unnecessarily obscure the gist of the embodiment, the detailed description will be omitted.

[0051]

[0052] According to one embodiment of the present invention, a p-type redox molecule, a solvent and a lithium salt are included,

[0053] The reduction potential of the above p-type redox molecule is vs. Li / Li + ) Provides a regeneration solution for a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less.

[0054] When the lithium ions of the lithium salt, the p-type redox molecules, and the positive electrode from which some lithium ions have been removed are mixed with each other, the redox molecules are oxidized, the positive electrode active material is reduced, and lithium ions and electrons move from the p-type redox molecules to the positive electrode active material through a thermodynamic spontaneous reaction.

[0055] Through this principle, lithium can be inserted into the cathode material from which lithium ions of a waste secondary battery have been desorbed.

[0056] Meanwhile, the p-type redox molecule for inducing a spontaneous reaction must i) be oxidized in a neutral state and exist in the form of a cation, ii) have an oxidation / reduction potential lower than the general charge start voltage of the positive electrode (3.7 V for NMC), and iii) have a reduction potential (Mn for NMC) that induces this to prevent material deterioration due to excessive lithium insertion. 3+ / Mn 4+ The reduction potential must be higher than 1.55 V.

[0057] These p-type redox molecules may specifically have a reduction potential of 1.55 V or more and 3.7 V or less, 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 may react with oxygen present in the atmosphere (~2.96 V), which may limit its handling under the atmosphere.

[0058] The types of p-type redox molecules satisfying all of the conditions of the above i) to iii) may include molecules such as N,N'-substituted phenazine, phenoxazine, phenylamine, phenothiazine, carbazole, phenylamine, thianthrene, dibenzodioxin, viologen, nitroxide radical compound, polyaniline, polythiophene, polytriphenylamine, polydiphenylamine, ferrocene, and manganocene, and the molecules may include an alkyl group (-R) having 1 to 5 carbon atoms, a hydroxyl group (-OH), It may be substituted with one or more of an amine group (-NH2), a phenyl group (-Ph), a benzoate group (-BzO), an acetyl group (-CH3CO), a carboxyl group (-COOH), and a benzoyl group (-COC6H5). Meanwhile, among these, the nitroxide radical compound may more specifically include proxyl, nitroxylbenzene, nitronylnitroxyl, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), etc.

[0059] In one embodiment of the present invention, the preferred type of p-type redox molecule may correspond to 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene or manganocene, which can be oxidized in a neutral state and exist in a cation form and can cause an oxidation / reduction reaction at about 3.27 to 3.45 V.

[0060]

[0061] The solvent included in the regeneration solution according to one embodiment of the present invention may include a cyclic ether solvent, a linear ether solvent, a carbonate (ester) solvent, acetonitrile, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethyl acetamide (DMAC), water (H2O), and the like.

[0062] The above solvents are stable at the desired positive electrode operating potential, can dissolve lithium salts and redox molecules, and do not cause side reactions.

[0063] Specific types of the above 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, and the like.

[0064] 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, and the like.

[0065] Specific types of the above 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, and the like.

[0066]

[0067] The lithium salt included in the regeneration solution according to one embodiment of the present invention is not particularly limited as long as it is a substance that can be dissolved in the solvent and provide lithium ions to the cathode material from which lithium ions have been desorbed, but specifically, it may include lithium bistrifluoromethanesulfonimide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonimide (LiFSI), lithium trifluoromethanesulfonate (LiTf), lithium trifluoromethanesulfone (LiOTF), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium difluorooxalatomolate (LiDFOB), lithium bisoxalateborate (LiBOB), lithium chloride (LiCl), lithium nitrate (LiNO3), lithium sulfate (LiSO4), lithium acetate (LiOAc), etc., and more specifically, lithium bistrifluoromethanesulfonimide (LiTFSI), lithium It is preferable to use a lithium salt containing hexafluorophosphate (LiPF6).

[0068]

[0069] The types of cathode materials into which lithium ions can be inserted through the regeneration solution according to one embodiment of the present invention include Li[NiCoMn]O2, LiCoO2, Li[NiCoAl]O2, Li[NiCoMnAl]O2, doped-Li[NiCoMn][M]O2, LiMn2O4, LiFePO4, Li[FeMn]PO4, LiNi 0.5 Mn 1.5 O4, etc. can be mentioned, and specifically, it can include Li[NiCoMn]O2(NMC) with a charge start voltage of about 3.7 V, LiCoO2(LCO) with a charge start voltage of about 3.9 V, Li[NiCoAl]O2(NCA) with a charge start voltage of about 3.6 V, LiFePO4(LFP) with a charge start voltage of about 3.4 V, etc.

[0070]

[0071] Meanwhile, according to one embodiment of the present invention, there is provided a step (S1) of preparing a regeneration solution by dissolving a lithium salt and a p-type redox molecule in a solvent;

[0072] A step (S2) of supporting a cathode material or a cathode from which lithium has been desorbed in the above solution;

[0073] A step (S3) of recovering and washing the loaded cathode material from the solution; and

[0074] Step of drying the above cathode material (S4);

[0075] Includes,

[0076] The reduction potential of the above p-type redox molecule is vs. Li / Li + ) A method for regenerating a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less is provided.

[0077] In the above regeneration method, the lithium salt, p-type redox molecule and solvent used may be considered to be substantially the same as those described in the regeneration solution for the waste secondary battery cathode material described in detail above, and preferably, the lithium salt includes at least one of lithium bistrifluoromethanesulfonylimide (LiTFSI) and lithium hexafluorophosphate (LiPF6), the p-type redox molecule includes at least one of 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene and manganocene, and the solvent may include at least one of dimethoxyethane (DME) and methyltetrahydrofuran.

[0078]

[0079] In the method for regenerating the above-mentioned waste secondary battery cathode material, as in the examples described in detail below, when a regeneration solution is prepared by dissolving lithium bistrifluoromethanesulfonylimide (LiTFSI) and 5,10-dihydro-5,10-dimethylphenazine (DMPZ) in 1,2-dimethoxyethane (DME), when the cathode material from which lithium has been desorbed is supported in the regeneration solution, the following reaction occurs, and through this, it is possible to obtain a regenerated cathode material with a recovered lithium composition.

[0080] xDMPZ + xLi + + xTFSI - + Li 1-y [NiCoMn]O2→ x(DMPZ + -TFSI - ) + Li 1-y+x [NiCoMn]O2(0 <x≤y)

[0081]

[0082] Meanwhile, the step of supporting the positive electrode material in the above-mentioned manufactured regeneration solution may be a reaction that occurs at room temperature (about 25°C), normal pressure (about 1 atm) and in a dry atmosphere without a separate heat treatment, base treatment, toxic gas treatment, etc., and the supporting time may be 0.25 hours or more, and the upper limit thereof is not significantly limited, but may be, for example, 0.25 hours or more and 10 hours or less, or 0.5 hours or more and 5 hours or less.

[0083] The method for regenerating a cathode material according to one embodiment of the present invention has the advantages of high mass productivity and reproducibility in that a reaction occurs easily and stably simply by supporting the cathode material in a solution without using separate lithium metal and without quantitative determination of the lithium composition, and the lithium insertion reaction occurs only until the potential of the cathode material reaches the oxidation / reduction potential of the p-type redox molecule without excessive lithium insertion.

[0084] The cathode material used in the method for regenerating the above-mentioned waste secondary battery cathode material is not particularly limited as long as it has part or all of the lithium removed, but as an example, it may have about 5% or more of the initial lithium amount of the cathode material removed.

[0085] In this case, the regeneration solution used with the positive electrode material may contain a lithium salt and a p-type redox molecule each corresponding to 1.5 times or more of the lithium deficiency of the positive electrode material, and the upper limit is not particularly limited, but may be 20 times or less, specifically 10 times or less, and more specifically 3 times or more and 5 times or less.

[0086] After performing the above-described loading step, the positive electrode material is recovered and washed. This washing process can be performed using the same type of solvent as that used in the previous regeneration solution. This process removes residual lithium salts and p-type redox molecules such as DMPZ present in the regenerated positive electrode material. After a subsequent drying process, the regenerated positive electrode material can be used in electrode manufacturing.

[0087]

[0088] Meanwhile, according to one embodiment of the present invention, a regeneration solution used for regenerating a cathode material is mixed with a reducing substance including lithium to reduce redox molecules, and is regenerated through a filtration process, thereby providing a recycling method that can be used again as a regeneration solution.

[0089] At this time, the lithium-containing reducing material used may be Li2CO3, Li2O2, LiO2, LiO, Li2O, Li2S, etc., and through this, not only the cathode material can be regenerated, but also the regeneration solution can be recycled, which has the advantage of ensuring higher economic feasibility.

[0090]

[0091] Hereinafter, the composition and resulting effects of the present invention will be described in more detail through examples and comparative examples. However, these examples are intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these examples.

[0092]

[0093] -Example

[0094] 1. Manufacturing example: Manufacturing of regeneration solution

[0095] A regeneration solution was prepared by dissolving lithium bistrifluoromethanesulfonylimide (LiTFSI) and 5,10-dihydro-5,10-dimethylphenazine (DMPZ) in 1,2-dimethoxyethane (DME) solvent.

[0096]

[0097] 2. Test Example 1: Electrochemical detection of positive electrode lithium recovery reaction (Fig. 3)

[0098] In a three-electrode system with an NMC 622 electrode charged to 30% of the reversible capacity as a working electrode, platinum as a counter electrode, and lithium as a reference electrode, DMPZ was added to an electrolyte containing only LiTFSI, and the change in voltage over time was observed (Fig. 3).

[0099] As shown in Fig. 3, immediately after adding DMPZ to the LiTFSI electrolyte to create a 21 mM DMPZ, 22.5 mM LiTFSI solution, the color of the solution rapidly changed to dark green. The voltage of the working electrode also rapidly decreased from 3.6 V or more to 3.17 V and then converged after the addition of DMPZ.

[0100] The open circuit voltage of the working electrode converges to 3.17 V, which is a value close to the redox voltage of DMPZ. It was confirmed through the change in color and the convergent voltage value that lithium was inserted into the NMC active material by oxidation of DMPZ, thereby lowering the voltage of the working electrode.

[0101]

[0102] 3. Test Example 2: Observation of the recovery of the cathode material lattice constant and the cathode material nickel oxidation number through the cathode lithium recovery reaction (Figs. 4 and 5)

[0103] (1) Recovery of the anode material lattice constant (Fig. 4)

[0104] X-Ray Diffraction (XRD) analysis was performed on a new NMC 622 electrode, an NMC 622 electrode charged to 30% of its reversible capacity after two charge-discharge cycles, and an electrode regenerated by soaking in a 140 mM DMPZ + LiTFSI regeneration solution containing 10 times the lithium deficiency amount for 2 hours in an argon atmosphere at room temperature after 30% charge.

[0105] As shown in Fig. 4, the (003) peak of the new electrode is located at the highest angle of 18.64 degrees, and after 30% charging, it shifts to a smaller angle 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.

[0106] The (003) peak position of the 30% charged electrode is restored to a similar level to that of a new NMC 622 electrode after regeneration, indicating that lithium is inserted into the active material after regeneration and the lattice structure is restored, so the lattice constant of the c-axis, which had increased due to lithium desorption, decreases, and the lattice constant of the a-axis, which had decreased, increases.

[0107] (2) Recovery of nickel oxidation number of cathode material (Fig. 5)

[0108] The difference in lithium composition of each sample's active material was analyzed by comparing the oxidation number of nickel present in the NMC 811 active material for each sample using Near-Edge X-ray Absorption Fine Structures (NEXAFS) analysis.

[0109] A new pouch cell (f-NMC) and a pouch cell that had deteriorated and lost 20% of its capacity (d-NMC) were discharged before disassembling the cells to prepare fully discharged f-NMC-d and d-NMC-d. Each separated cathode was then assembled into a new coin cell and charged to prepare charged f-NMC-c and d-NMC-c. In addition, the cathode active material was separated from the deteriorated pouch cell and regenerated by soaking it in a 140 mM DMPZ + LiTFSI regeneration solution three times the lithium deficiency amount in a dry atmosphere at room temperature for 2 h and then made into an electrode again (r-NMC). The NEXAFS analysis results of these five samples were compared.

[0110] As shown in Fig. 5, the L3 peak of nickel of f-NCM and r-NCM at 857 eV indicated a high lithium content and a low (reduced) nickel oxidation number in the anode. And the L3 peak of nickel of d-NCM-c and f-NCM-c at 858 eV indicated a high lithium content and a high (oxidized) nickel oxidation number in the anode. Considering that the L3 peak of r-NCM has a lower energy than that of d-NCM-d, it can be seen that lithium was sufficiently introduced into the cathode material after the regeneration treatment, and the oxidation number of nickel was recovered.

[0111]

[0112] 4. Test Example 3: Experiment to evaluate the electrochemical characteristics of a regenerated cathode according to recycling conditions (Figs. 6 to 10)

[0113] (1) Results of evaluation of the electrochemical characteristics of the regenerative anode according to the lithium salt concentration and the presence or absence of p-type redox molecules (Fig. 6)

[0114] After two charge-discharge cycles of NMC 622 coin cells, the NMC 622 electrodes were separated after being charged to 30% of the reversible capacity. The cathodes were then regenerated by immersing them in a solution containing only LiTFSI without DMPZ (0.14 M LiTFSI) and a regeneration solution containing DMPZ for 2 h in an argon atmosphere at room temperature. The regeneration solution containing DMPZ equivalent to 3 times (0.042 M DMPZ + 0.042 M LiTFSI) and 1.5 times (0.021 M DMPZ + 0.021 M LiTFSI) the lithium deficiency of the cathode, respectively, was used.

[0115] Each of the regenerated electrodes treated under the above three conditions was used as a positive electrode, a lithium metal chip punched to a diameter of 16 mm was used as a negative electrode, Celgard was used as a separator, and a 1 M LiPF6EC / DEC electrolyte was used to fabricate a CR2032 type battery. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, to evaluate the change in coulombic efficiency depending on whether it was recycled.

[0116] As shown in Fig. 6, after immersing the electrode in a solution without DMPZ, 130 mAh g was reassembled. -1 The first charge capacity was reduced (there was no lithium insertion), but when the electrode was immersed in a regeneration solution containing DMPZ, the charge capacity was recovered by 100.5% when the amount of DMPZ was 3 times that of the lithium deficiency, and by 100.4% when it was 1.5 times that, and when the amount of DMPZ was large compared to the lithium deficiency, the charge capacity was recovered to close to 100% regardless of the amount of DMPZ compared to the lithium deficiency.

[0117] (1) Results of evaluation of electrochemical characteristics of regenerated cathode according to heterogeneous waste cathode lithium composition (Fig. 7)

[0118] Three NMC 622 coin cells were each subjected to two cycles of charge-discharge, each to 15%, 30%, and 45% of its reversible capacity, after which the NMC electrodes were separated. After separation of the NMC electrodes, the three electrodes were regenerated by immersing them in a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) for 1 h at room temperature in an argon atmosphere. The amount of regeneration solution used was 10 times the sum of the lithium deficiencies of the three cathodes.

[0119] Each of the regenerated electrodes treated under the above three conditions was used as a positive electrode, a lithium metal chip punched to a diameter of 16 mm was used as a negative electrode, Celgard was used as a separator, and a 1 M LiPF6EC / DEC electrolyte was used to fabricate a CR2032 type battery. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, to evaluate the change in coulombic efficiency depending on whether it was recycled.

[0120] As shown in Fig. 7, after simultaneously immersing the electrodes in the regeneration solution and regenerating them, the electrodes that were charged to 15%, 30%, and 45% of their reversible capacities recovered their initial charge capacities after reassembly to 103%, 106%, and 104%, respectively. As a result, it was confirmed that the regeneration solution is capable of regenerating waste cathode materials having a heterogeneous lithium composition.

[0121] (3) Results of evaluation of electrochemical characteristics of regenerated cathode according to lithium composition of waste cathode material (highly desorbed state) (Fig. 8)

[0122] After two charge-discharge cycles of the NMC 622 coin cell, the NMC electrode was separated after being charged to 90% of the reversible capacity. After the NMC electrode was separated, a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) corresponding to 10 times the lithium deficiency of the spent cathode was used for regeneration for 2 h in an argon atmosphere at room temperature.

[0123] A CR2032 type battery was manufactured using the regenerated electrode processed under the above conditions as the positive electrode, a lithium metal chip punched to a diameter of 16 mm as the negative electrode, Celgard as the separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, to evaluate the change in coulombic efficiency depending on whether it was recycled.

[0124] As shown in Fig. 8, after the electrode was regenerated by immersing it in a regeneration solution, the electrode, which had been charged to 90% of its reversible capacity, showed a first charge capacity of 103% after reassembly, confirming that it can be successfully regenerated even when the lithium deficiency of the waste positive electrode is large.

[0125] (4) Results of evaluation of the electrochemical characteristics of the regenerative anode according to the type of solvent under dry conditions (Fig. 9)

[0126] After two charge-discharge cycles of NMC 622 coin cells, the NMC electrodes were separated after being charged to 30% of their reversible capacity. The separated NMC electrodes were then regenerated by immersion in regeneration solutions using DME or 2-meTHF solvents for 2 h at room temperature and in a dry atmosphere. The regeneration solutions (0.14 M DMPZ + 0.14 M LiTFSI) were used in amounts 10 times the lithium deficiency of the cathode, respectively.

[0127] Each regenerated electrode treated under the above two solvent conditions was used as a positive electrode, a lithium metal chip punched to a diameter of 16 mm was used as a negative electrode, Celgard was used as a separator, and a 1 M LiPF6EC / DEC electrolyte was used to fabricate a CR2032 type battery. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C to evaluate the change in coulombic efficiency depending on whether it was recycled.

[0128] Electrodes regenerated with different solvents, DME and 2-meTHF, in a dry atmosphere showed initial Coulombic efficiencies of 100% and 103%, respectively, confirming that the active material was successfully regenerated even when regeneration was performed while exposed to a dry atmosphere or when regeneration solutions using different solvents were used.

[0129] (5) Evaluation of the life characteristics of the regenerated anode (Fig. 10)

[0130] After two charge-discharge cycles of the NMC 622 coin cell and charging to 30% of the reversible capacity, the NMC electrode was removed and regenerated by immersing in a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) using 2-meTHF solvent for 2 hours at room temperature in a dry atmosphere. The regeneration solution was used in an amount corresponding to 10 times the lithium deficiency of the positive electrode. In addition, in order to observe the presence or absence of electrode deterioration during the regeneration process, a sample (DMPZ-free) containing an electrode charged under the same conditions was prepared using a 0.14 M LiTFSI solution without DMPZ.

[0131] Each electrode processed under the above conditions was used as a positive electrode, a lithium metal chip punched to a diameter of 16 mm was used as a negative electrode, Celgard was used as a separator, and a 1 M LiPF6EC / DEC electrolyte was used to manufacture a CR2032 type battery. The battery was charged and discharged three times at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, and thereafter at a current density of 0.5 C, to evaluate the change in life characteristics depending on whether it was recycled.

[0132] As shown in Fig. 10, the electrode regenerated using 2-meTHF solvent under dry air conditions maintained 85.9% of its capacity after 200 cycles, which was not significantly different from the capacity retention rate of 86.3% of the electrode treated without DMPZ. This confirmed that the regeneration treatment did not adversely affect the life of the anode.

[0133]

[0134] 5. Test Example 4: Analysis of lithium recovery degree according to positive electrode regeneration reaction time (Fig. 11)

[0135] After two charge-discharge cycles of NMC 622 coin cells, the cells were recharged to 30% of their reversible capacity. The NMC electrodes were separated and immersed in a DME-based 0.042 M DMPZ + 0.042 M LiTFSI regeneration solution at room temperature in an argon atmosphere for varying immersion times to compare the degree of regeneration according to the immersion time. In the case of the electrodes immersed for 0.25 h, the degree of regeneration according to temperature was also compared by treating them at two different temperatures, room temperature and 50℃.

[0136] A CR2032 type battery was manufactured using the electrode processed under each of the above time conditions as the positive electrode, a lithium metal chip punched to a diameter of 16 mm as the negative electrode, Celgard as the separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C.

[0137] As shown in Fig. 11, as the electrode immersion time in the solution increased from 0.25 hours to 2 hours, the Coulombic efficiency converged to 100% and saturated around 1 hour. In addition, when the active material was regenerated at 50°C, it was confirmed that faster regeneration was possible by raising the temperature, as shown by the recovery of the saturated charge capacity close to 100% in just 15 minutes.

[0138]

[0139] 6. Test Example 5: Rate capability and life characteristics evaluation results according to cathode material type (Fig. 12)

[0140] (a) LiNi recovered from new pouch cells 0.8 Mn 0.1 Co 0.1A total of three NMC 811 cathodes were manufactured by mixing the cathode powder (pristine) of O2 (NMC 811), (a) cathode powder (degraded) recovered from a pouch cell with a capacity reduced by 20%, and (b) powder (after regeneration) obtained by soaking the cathode in a regeneration solution (0.14 M DMPZ + 0.14 M LiTFSI) containing three times the amount of lithium deficiency for 2 hours in a dry atmosphere at room temperature.

[0141] A CR2032 type battery was manufactured using a NMC 811 electrode punched to a diameter of 11.3 mm as a positive electrode, a lithium metal chip punched to a diameter of 16 mm as a negative electrode, Celgard as a separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C for 3 cycles in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 3.0 V at a room temperature of 30°C, and then at a current density of 0.5 C to evaluate the lifespan characteristics according to whether it was recycled. In addition, in order to confirm the difference in rate characteristics according to whether it was recycled, the rate characteristics were evaluated by changing the rate in the order of 0.1 C, 0.5 C, 1 C, 2 C, 3 C, and then 0.5 C again.

[0142] As shown in Fig. 12, the degraded NMC 811 cathode has a capacity of 159.1 mAh g, which is 18.1% less than that of the new cathode at the first charge. -1 It showed a capacity of 202.3 mAh g after playback. -1 The first charge capacity was recovered. Even after 150 charge-discharge cycles, the new and regenerated anodes showed no difference in capacity retention.

[0143] And regardless of whether it was recycled or not, it showed the same rate characteristics under current density conditions of 0.1 C to 3 C, confirming that the waste cathode regeneration treatment can be applied to NMC 811 regardless of the type of cathode material and does not affect the rate characteristics of the active material.

[0144]

[0145] 7. Test Example 6: Experiment according to the type of p-type redox molecule (Figs. 13 and 14)

[0146] (1) Redox voltage analysis according to DPPD or DBB application (Fig. 13)

[0147] The redox voltage of each redox molecule was analyzed through cyclic voltammetry (CV voltammetry) experiments using a regeneration solution containing 21 mM N,N'-diphenyl-p-phenylenediamine (DPPD) or 1,4-di-tert-butyl-2,5-dimethoxybenzene (DBB) as a p-type redox molecule and 21 mM LiTFSI as a lithium salt.

[0148] After 30 mL of regeneration solution was injected as electrolyte into a coin cell with a stainless steel plate with a diameter of 16 pi as a working electrode, a lithium metal chip punched to have a diameter of 16 mm as a cathode, and Celgard as a separator, a voltage of 1 mV s was applied. -1 Voltage was injected at a rate of .

[0149] As shown in Fig. 13, DPPD has a sufficiently low reduction potential of 3.45 V, which allows it to be utilized as a p-type redox molecule in a regeneration solution. However, DBB has a reduction potential of 4.25 V, which is higher than the charging start voltage of NMC, 3.6 V, and thus is unsuitable for use as a p-type redox molecule in a regeneration solution.

[0150] (2) Evaluation of changes in Coulombic efficiency according to application of DPPD or DBB (Fig. 14)

[0151] After two charge-discharge cycles of the NMC 622 coin cell, the NMC electrode was separated after being charged to 30% of the reversible capacity. After separating the NMC electrode, the cathode was regenerated by immersing it in (a) a regeneration solution using DPPD (0.14 M DPPD + 0.14 M LiTFSI) and (b) a regeneration solution using DBB (0.14 M DBB + 0.14 M LiTFSI) for 0.25 h in an argon atmosphere at room temperature. An amount of regeneration solution equivalent to 10 times the lithium deficiency of the cathode was used.

[0152] Each electrode treated under the above conditions was used as a positive electrode, a lithium metal chip punched to a diameter of 16 mm was used as a negative electrode, Celgard was used as a separator, and a 1 M LiPF6EC / DEC electrolyte was used to manufacture a CR2032 type battery. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, and the change in coulombic efficiency depending on whether it was recycled was evaluated.

[0153] As shown in Fig. 14, the first coulombic efficiency recovered by 98.3% after the electrode was immersed in the solution using DPPD (upper graph of Fig. 14), but when the electrode was immersed in the regeneration solution using DBB, the first charge capacity was 81.3% (lower graph of Fig. 14). This confirmed that DPPD with an appropriate reduction potential (3.45 V) can regenerate the positive electrode, but DBB with a reduction potential that is not low enough (4.24 V) cannot regenerate the active material.

[0154]

[0155] 8. Test Example 7: Cathode regeneration experiment according to lithium salt type (Fig. 15)

[0156] After two charge-discharge cycles of the NMC 622 coin cell, the NMC electrode was separated after being charged to 30% of the reversible capacity. After separating the NMC electrode, the cathode was regenerated by immersing it in a regeneration solution using LiPF6 and DMPZ in an argon atmosphere at room temperature for 0.25 h. The amount of regeneration solution (0.14 M DMPZ + 0.14 M LiPF6) was 10 times the lithium deficiency of the cathode.

[0157] A CR2032 type battery was manufactured using the regenerated electrode processed under the above conditions as the positive electrode, a lithium metal chip punched to a diameter of 16 mm as the negative electrode, Celgard as the separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, and the change in coulombic efficiency depending on whether it was recycled was evaluated.

[0158] As shown in Fig. 15, even when a regeneration solution utilizing LiPF6 was used, the first charge capacity after reassembly was 98.2%, confirming that NMC active material can be successfully regenerated even when a lithium salt other than LiTFSI is used.

[0159]

[0160] 9. Test Example 8: Verification of Recycling Reaction after Use of Regeneration Solution (Fig. 17)

[0161] Three solutions were analyzed using UV-vis absorbance spectroscopy: a fresh regeneration solution, the solution used to regenerate the electrode, and the used solution restored by adding Li2O2.

[0162] The peak around 339 nm represents unoxidized neutral DMPZ, and the peaks around 400-500 nm and 600-750 nm represent oxidized DMPZ. +In Fig. 17, after the new regeneration solution containing only neutral DMPZ was used, DMPZ + Peaks appear, and after restoration via Li2O2, DMPZ + As the peak disappears again, it can be seen that the oxidized DMPZ during the regeneration process is reduced back to neutral DMPZ during the restoration process.

[0163]

[0164] 10. Test Example 9: Lifetime test of NMC 622 electrode regenerated through recycling of regeneration solution (Fig. 19)

[0165] The electrode, which had been delithiated to 30% of its reversible capacity, was regenerated by immersing it in a recycled regeneration solution (RY-NCM) for 2 h under an argon atmosphere. The recycled regeneration solution was obtained by mixing Li2O2 with the used regeneration solution. In addition, to observe the presence or absence of electrode degradation in the regeneration solution, a sample (DMPZ-free) was prepared by immersing the 30%-charged electrode in a 0.14 M LiTFSI solution without DMPZ under the same conditions.

[0166] To prepare the used regeneration solution, NMC 622 coin cells were charged to 30% of their reversible capacity after two charge-discharge cycles, and then the NMC electrodes were separated. After separating the NMC electrodes, the electrodes were regenerated using a regeneration solution containing 1.5 times the amount of DMPZ and LiTFSI compared to the lithium deficiency of the desorbed cathode. The used regeneration solution was then recovered for the recycling process.

[0167] A CR2032 type battery was manufactured using the electrode regenerated under the above conditions as the positive electrode, a lithium metal chip punched to 16 mm as the negative electrode, Celgard as the separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C for two cycles in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C, and then at a current density of 0.5 C to evaluate the life characteristics depending on whether the solution was recycled.

[0168] As shown in Fig. 19, when the electrode was regenerated using the restored regeneration solution, the first charge capacity after assembly was recovered by 102.7%, and the capacity retention rate was 85.3% after 200 cycles, and it was confirmed that there was no adverse effect on the lifespan by regeneration using the recycled regeneration solution.

[0169]

[0170] 11. Test Example 10: Evaluation of electrochemical characteristics of regenerated cathode according to solvent (Fig. 20)

[0171] (1) Manufacturing of regenerated NMC cathode

[0172] After two charge-discharge cycles, NMC 622 coin cells were charged to 30% of their reversible capacity, and then the NMC electrodes were separated. Subsequently, they were regenerated by immersing them in a regeneration solution (0.1 M ferrocene + 0.1 M LiTFSI) for 1 h in an argon atmosphere at 30°C. The regeneration solution solvents used were 1,3-dioxolane, dimethyl carbonate, 2-methylhydrofuran, acetonitrile, and N,N-dimethylformamide, respectively. The regeneration solution used contained DMPZ and LiTFSI in amounts 10 times greater than the lithium deficiency in the NMC electrode active material.

[0173] (2) Evaluation of changes in Coulomb efficiency

[0174] A CR2032 type battery was manufactured using the electrode regenerated under each of the above solvent conditions as the positive electrode, a lithium metal chip punched to a diameter of 16 mm as the negative electrode, Celgard 2320 as the separator, and 1 M LiPF6EC / DEC electrolyte. The battery was charged and discharged at a current density of 0.1 C in the range of an upper charge voltage of 4.3 V and a lower discharge voltage of 2.5 V at a room temperature of 30°C to evaluate the change in coulombic efficiency depending on whether it was recycled or not, and the results are shown in Fig. 20.

[0175] (3) Evaluation of the first charge capacity after reassembly of the regenerated electrode

[0176] The electrodes regenerated using regeneration solutions of 1,3-dioxolane, dimethyl carbonate, 2-methyltetrahydrofuran, acetonitrile, and N,N-dimethylformamide showed first charge capacities after reassembly of 106.43%, 108.80%, 105.36%, 101.00%, and 107.20%, respectively, confirming that NMC electrodes can be regenerated using various organic solvents.

[0177]

[0178] Although the embodiments described above have been described with limited drawings, those skilled in the art will appreciate that various technical modifications and variations can be applied based on the above. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or the described components are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0179] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. Containing a p-type redox molecule, a solvent and a lithium salt, The reduction potential of the above p-type redox molecule is compared to the reduction potential of lithium (vs Li / Li + ) A regeneration solution for a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less.

2. In paragraph 1, The reduction potential of the above p-type redox molecule is compared to the reduction potential of lithium (vs Li / Li + ) A regeneration solution for a waste secondary battery cathode material having a voltage of 2.9 V or more and 3.6 V or less.

3. In paragraph 1, The above p-type redox molecule comprises at least one molecule selected from the group consisting of N,N'-substituted phenazine, phenoxazine, phenylamine, phenothiazine, carbazole, phenylamine, thianthrene, dibenzodioxin, viologen, nitroxide radical compound, polyaniline, polythiophene, polytriphenylamine, polydiphenylamine, and ferrocene, manganocene, A regeneration solution for a waste secondary battery cathode material, wherein the molecule may be substituted with one or more of an alkyl group (-R), a hydroxyl group (-OH), an amine group (-NH2), a phenyl group (-Ph), a benzoate group (-BzO), an acetyl group (-CH3CO), a carboxyl group (-COOH), and a benzoyl group (-COC6H5) having 1 to 5 carbon atoms.

4. In paragraph 1, A regeneration solution for a waste secondary battery cathode material, wherein the solvent comprises at least one selected from the group consisting of a cyclic ether solvent, a linear ether solvent, a carbonate (ester) solvent, acetonitrile, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethyl acetamide (DMAC), and water (H2O).

5. In paragraph 4, A regeneration solution for a waste secondary battery cathode material, wherein the cyclic ether solvent comprises at least one selected from the group consisting of 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, and dimethyloxetane.

6. In paragraph 4, A regeneration solution for a waste secondary battery cathode material, wherein the linear ether solvent comprises at least one 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. In paragraph 4, A regeneration solution for a waste secondary battery cathode material, wherein the carbonate solvent comprises at least one 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 butyrate, ethyl butyrate, propyl butyrate, methyl lactate, ethyl lactate, methyl phenyl lactate, methyl propionate, triacetin, ethyl acetoacetate, dimethyl adipate, benzyl benzoate, and ethyl formate.

8. In paragraph 1, A regeneration solution for a waste secondary battery cathode material, wherein the lithium salt comprises at least one selected from the group consisting of lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonyl imide (LiFSI), lithium trifluoromethanesulfonate (LiTf), lithium trifluoromethanesulfone (LiOTF), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium difluorooxalatomolate (LiDFOB), lithium bisoxalateborate (LiBOB), lithium chloride (LiCl), lithium nitrate (LiNO3), lithium sulfate (LiSO4), and lithium acetate (LiOAc).

9. In paragraph 1, The above cathode materials are Li[NiCoMn]O2, LiCoO2, Li[NiCoAl]O2, Li[NiCoMnAl]O2, doped-Li[NiCoMn][M]O2, LiMn2O4, LiFePO4, Li[FeMn]PO4, and LiNi 0.5 Mn 1.5 A regeneration solution for a waste secondary battery cathode material, comprising at least one selected from the group consisting of O4.

10. Step (S1) of preparing a regeneration solution by dissolving a lithium salt and a p-type redox molecule in a solvent; Step (S2) of placing a cathode material from which lithium has been desorbed in the above solution; A step (S3) of recovering and washing the loaded cathode material from the solution; and Step of drying the above cathode material (S4); Includes, The reduction potential of the above p-type redox molecule is vs. Li / Li + ) A method for regenerating a waste secondary battery cathode material having a voltage of 1.55 V or more and 3.7 V or less.

11. In paragraph 10, The lithium salt comprises at least one of lithium bistrifluoromethanesulfonylimide (LiTFSI) and lithium hexafluorophosphate (LiPF6), The above p-type redox molecule comprises at least one of 5,10-dihydro-5,10-dimethylphenazine (DMPZ), N,N'-diphenyl-p-phenylenediamine (DPPD), ferrocene, and manganocene, A method for regenerating a waste secondary battery cathode material, wherein the solvent comprises at least one of dimethoxyethane (DME), 1,3-dioxolane (DOL), 2-methylhydrofuran (2meTHF), acetonitrile (ACN), and N,N-dimethylformamide (DMF).

12. In paragraph 10, The above S2 step is a method for regenerating a waste secondary battery cathode material, which includes storing at room temperature and pressure for 0.25 hours or more.

13. In paragraph 10, A method for regenerating a waste secondary battery cathode material, wherein the cathode material from which lithium has been desorbed has lithium desorbed from at least 5% of the initial amount of lithium.

14. In paragraph 10, A method for regenerating a cathode material of a waste secondary battery, wherein the regeneration solution is a regeneration solution containing a lithium salt and a p-type redox molecule, each corresponding to 1.5 times or more of the lithium deficiency of the cathode material.

15. In paragraph 10, A method for regenerating a waste secondary battery cathode material, wherein the washing in the above step S3 is performed using the same solvent as the solvent of the regeneration solution.

16. A cathode material regenerated with a regeneration solution according to Article 1. 17.(a) A step of regenerating a waste secondary battery cathode material using the regeneration solution described in paragraph 1; and (b) a step of mixing the utilized regeneration solution with a reducing material including lithium; Includes, A method for recycling a regeneration solution, wherein the reducing material including lithium is at least one selected from the group consisting of Li2CO3, Li2O2, LiO2, LiO, Li2O and Li2S.

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