WO2025239590A1 - Chemical peeling process and material of waste positive electrode scrap - Google Patents

Abstract

The present invention relates to a method for recovering a positive electrode active material from a waste positive electrode scrap through chemical peeling and, more specifically, to a method capable of efficiently recovering a positive electrode active material from a waste positive electrode scrap without damage to a current collector by comprising the steps of: preparing a peeling solution by adding an aromatic hydrocarbon and lithium to an organic solvent; and impregnating the waste positive electrode scrap containing the positive electrode active material with the peeling solution.

Description

Chemical stripping process and materials for waste cathode scrap

The present invention relates to a method for chemically stripping active material from waste positive electrode scrap.

Lithium secondary batteries have long cycle lives and can be miniaturized, making them suitable for a variety of devices, including laptops and mobile phones. With the recent rise in demand for mobile devices and electric vehicles, demand for secondary batteries is also increasing. Consequently, the excessive amount of waste cathode scrap generated during the lithium secondary battery manufacturing process is becoming a growing issue.

Spent cathode scrap contains cathode active materials, which include expensive rare metals such as lithium, nickel, manganese, and cobalt. These metals are expensive, pose environmental problems, and are limited in number and therefore unstable in supply. Consequently, the need for methods to reuse or recycle cathode active materials from waste cathode materials, waste batteries, and other materials is recognized as a critical issue.

Conventional recycling technologies for waste cathode materials and lithium secondary batteries require shredding and separation processes. This process generates toxic gases, which can pose environmental problems. It also consumes significant energy. Furthermore, the presence of large amounts of impurities within the powder necessitates additional processing. Furthermore, conventional recycling techniques have low cathode active material stripping efficiency and can damage the aluminum current collector. Corrosion of the aluminum current collector generates aluminum hydroxide, requiring additional processing to separate the aluminum from the powder, which is a major drawback.

Accordingly, the inventors of the present invention completed the present invention by devising a chemical peeling method that does not require processes such as crushing while researching an environmentally friendly method that does not damage the entire body and enables peeling with high efficiency.

The present invention aims to provide a method for chemically stripping active material from waste positive electrode scrap.

1. A method for recovering a cathode active material from waste cathode scrap, comprising: a step of preparing a stripping solution by adding an aromatic hydrocarbon and lithium to an organic solvent; and a step of impregnating waste cathode scrap containing a cathode active material into the stripping solution.

2. A method for recovering positive electrode active material from waste positive electrode scrap, further comprising the steps of: removing the waste positive electrode scrap from the stripping solution in the above 1 and stripping it through physical treatment; and drying the stripped waste positive electrode scrap.

3. A method for recovering positive electrode active material from waste positive electrode scrap, further comprising a step of heat-treating the dried waste positive electrode scrap in the above 2.

4. A method for recovering a cathode active material from waste cathode scrap, wherein in the above 1, the cathode active material is LiNi _x Co _y Mn _z O ₂ (x+y+z=1).

5. In 1 above, the organic solvent is 1,2-Diethoxyethane, 1,2-Dimethoxyethane, 1,2-Dimethoxypropane, 1,3-Dioxane, 1,3-Dioxepin, 1,3-Dioxolane, 1,3,5-Trioxane, 1,4-Dioxane, 2-Ethoxyethanol, 2-Methyltetrahydrofuran, 2,2,5,5-Tetramethyltetrahydrofuran, Anisole, Benzyl Ether, Butyl Diglyme, Butyl Methyl Ether, Cyclohexyl Methyl Ether, Cyclopentyl Methyl Ether, Di(propylene glycol) methyl ether, Di-tert-butyl ether, Diethylene Glycol, Diethylene Glycol monomethyl ether, Diethyl Ether, Dibutyl Ether, Dimethoxymethane, Dimethyl Ether, Diisopropyl Ether, Diphenyl A method for recovering a cathode active material from waste cathode scrap, wherein the cathode active material is any one selected from the group consisting of Ether, Dipropyl Ether, Ethyl Methyl Ether, Ethyl Phenyl Ether, Ethyl tert-Butyl Ether, Ethylene Glycol Diethyl Ether, Ethylene Glycol Monobutyl Ether, Methyl tert-Butyl Ether, Morpholine, Tert-Amyl ethyl ether, Tert-Amyl methyl ether, Tetrahydrofuran, Tetrahydrofuran-D8, Tetrahydropyran, Tetrahydrofurfuryl Alcohol, and Triethylene Glycol Dimethyl Ether.

6. In 1 above, the aromatic hydrocarbons include 1,1-Diphenylethylene, 1,4-Di-tert-butyl-2,5-dimethoxybenzene, 2-Fluorobiphenyl, 2-Methylbiphenyl, 3,3'-Dimethylbiphenyl, 3,3',4,4',-Tetramethylbiphenyl, 4,4'-Dimethylbiphenyl, 4-Methylbiphenyl, 5,10-Dihydro-5,10-dimethylphenazine, 9,9-Dimethylfluorene, Acenaphthene, Acetophenone, Acridine, Anthracene, Benzo[a]pyrene, Benzo[b]fluoranthene, Benzimidazole, Benzofuran, Benzothiazole, Benzothiophene, Benzoxazole, Biphenyl, Carbazole, Chrysene, Coumarin, Ethylbenzene, Fluoranthene, Fluorene, Furan, A method for recovering a cathode active material from waste cathode scrap, wherein the cathode active material is any one selected from the group consisting of Hexacene, Imidazole, Indole, Isoindole, Isoquinoline, N,N'-Diphenyl-p-phenylenediamine, Naphthalene, Oxadiazole, Oxazole, Pentacene, Perfluorobenzene, Perylene, Phenanthrene, Phenazine, Phenothiazine, Phenylacetylene, Purine, Pyrazine, Pyridine, Pyrimidine, Pyrene, Pyrrole, Quinoline, Stilbene, Tetracene, Tetrazole, Thiazole, Thiadiazole, Thiophene, Toluene, Triazine, Triphenylene, Xanthine and Xylene.

7. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the concentration of aromatic hydrocarbon in the stripping solution in the above 1 is 0.5 to 5 M.

8. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the molar ratio of lithium and aromatic hydrocarbon in the stripping solution in the above 1 is 1:1 to 10:1.

9. A method for recovering positive electrode active material from waste positive electrode scrap, wherein in the above 1, the impregnation step is performed for 5 to 120 minutes.

10. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the impregnation step in the above 1 is performed at 20 to 80°C.

11. A composition for stripping waste cathode scrap containing an organic solvent, an aromatic hydrocarbon and lithium.

The present invention can provide a method for chemically stripping a cathode active material from waste cathode scrap.

The present invention can provide a method for chemically exfoliating an active material using an aromatic hydrocarbon, an organic solvent, and lithium metal.

The present invention can provide a peeling method that does not require crushing, separation or high-temperature heat treatment of waste cathode scrap.

The present invention can provide a method for peeling an active material without damaging an aluminum current collector.

The present invention can provide a reusable peeling solution.

Figure 1 is a schematic diagram simply showing a cathode active material stripping process using a lithium-aromatic complex.

Figure 2 shows the stripping efficiency when the molar concentration of pyrene and the molar concentration ratio of Li metal to pyrene in a pyrene/DME solution were varied. Each number represents the weight (wt%) of the electrode decreased due to stripping, and an increase in the weight (wt%) of the electrode is indicated by a + sign.

Figure 3a is a photograph of an electrode after peeling with a Pyrene/DME solution at high temperature and a photograph showing the peeling efficiency.

Figure 3b shows a photograph of an electrode after peeling with a Biphenyl/DME solution at high temperature and a photograph showing the peeling efficiency.

Figure 3c is a photograph of the electrode after peeling with a Pyrene/DME solution at room temperature and a photograph showing the peeling efficiency.

Figure 3d shows a photograph of the electrode after peeling with a Biphenyl/DME solution at room temperature and a photograph showing the peeling efficiency.

Figure 4a is a photograph of an electrode after peeling with a Naphthalene/DME solution at high temperature and a photograph showing the peeling efficiency.

Figure 4b is a photograph of an electrode after peeling with a Fluoranthene/DME solution at high temperature and a photograph showing the peeling efficiency.

Figure 5a is a graph comparing the peeling efficiency of each solution, and confirms the efficiency when peeling is performed at high temperature (High T) and room temperature (Room T) using Pyrene/DME and Biphenyl/DME.

Figure 5b is a graph comparing the peeling efficiency of each solution, and the efficiency was confirmed when peeling was performed using Pyrene/DME, Biphenyl/DME, Fluoranthene/DME, and Naphthalene/DME.

Figure 5c is a graph comparing the peeling efficiency of solutions, and confirms the efficiency when peeling is performed using Fluoranthene/DME (FR/DME) and Fluoranthene/THP (FR/THP).

Figure 6 is a photograph showing the ICP-OES results (#1 (Samp): Pristine NCM powder; #2 (Samp): Pyrene/DME delamination; #3 (Samp): N-Methyl-2-Pyrrolidone (NMP) delamination).

Figure 7a is an SEM image of the black powder after exfoliation, which is an SEM image of NCM811 powder and Pyrene/DMA after exfoliation for 20 minutes, respectively.

Figure 7b is an SEM photograph of the black powder after exfoliation, in the case of exfoliation with Biphenyl/DME for 20 minutes and in the case of ultrasonic exfoliation using NMP, respectively.

Figure 8 shows SEM images of black powder heat-treated after exfoliation, at 2500, 3500, and 10000x magnifications of Pristine NCM811 powder and a sample heat-treated after exfoliation with Pyrene/DME for 20 minutes.

The present invention provides a method for recovering positive electrode active material from waste positive electrode scrap through chemical peeling.

The present invention provides a method for recovering a cathode active material from waste cathode scrap, comprising the steps of: preparing a stripping solution by adding an aromatic hydrocarbon and lithium to an organic solvent; and impregnating waste cathode scrap containing a cathode active material into the stripping solution.

The method of the present invention is to impregnate waste positive electrode scrap in a stripping solution prepared by adding aromatic hydrocarbon and lithium to an organic solvent, thereby transforming the crystal structure of the positive electrode and allowing efficient stripping.

When one equivalent of lithium is additionally inserted into the cathode active material LiNi _x Co _y Mn _z O ₂ (x+y+z=1, NCM), the octahedral structure occupied by one lithium in the existing NCM structure is divided into two lithium ions, and as the two lithium ions occupy the tetrahedral sites, Li ₂ NCM (lithium rich NCM, LRNCM) is formed. Accordingly, the particle size of the active material becomes smaller, so the bonding force between the binder and the cathode material is weakened, which can make it easy to peel off. Thereafter, high-efficiency peeling is possible through simple physical treatment. The used stripping solution can be reused as is or by adding more lithium.

In the method of the present invention, by impregnating a waste cathode scrap into a stripping solution prepared by adding an aromatic hydrocarbon and lithium to an organic solvent, lithium and the aromatic hydrocarbon can form a liquid metal arene complex (LMAC).

"Spent cathode scrap" refers to waste generated during the production process of lithium secondary batteries or generated from spent batteries. Spent cathode scrap contains cathode active materials such as LiCoO ₂ , Li(Ni _x Mn _y Co _z )O ₂ or LiMnO ₂ . Specifically, the spent cathode scrap contains metals such as Co, Ni, Mn and Li, and may contain impurities such as Al, Fe and Cu.

In one embodiment, the positive active material may be LiNi _x Co _y Mn _z O ₂ (x+y+z=1).

In the present invention, aromatic hydrocarbons and aromatic heterocyclic compounds include 1,1-Diphenylethylene, 1,4-Di-tert-butyl-2,5-dimethoxybenzene, 2-Fluorobiphenyl, 2-Methylbiphenyl, 3,3'-Dimethylbiphenyl, 3,3',4,4',-Tetramethylbiphenyl, 4,4'-Dimethylbiphenyl, 4-Methylbiphenyl, 5,10-Dihydro-5,10-dimethylphenazine, 9,9-Dimethylfluorene, Acenaphthene, Acetophenone, Acridine, Anthracene, Benzo[a]pyrene, Benzo[b]fluoranthene, Benzimidazole, Benzofuran, Benzothiazole, Benzothiophene, Benzoxazole, Biphenyl, Carbazole, Chrysene, Coumarin, Ethylbenzene, Fluoranthene, Fluorene, Furan, Hexacene, Imidazole, Indole, Isoindole, Isoquinoline, N,N'-Diphenyl-p-phenylenediamine, Naphthalene, Oxadiazole, Oxazole, Pentacene, Perfluorobenzene, Perylene, Phenanthrene, Phenazine, Phenothiazine, Phenylacetylene, Purine, Pyrazine, Pyridine, Pyrimidine, Pyrene, It may be Pyrrole, Quinoline, Stilbene, Tetracene, Tetrazole, Thiazole, Thiadiazole, Thiophene, Toluene, Triazine, Triphenylene, Xanthine or Xylene.

In the present invention, the aromatic hydrocarbon can interact with lithium ions and can be any aromatic hydrocarbon exhibiting a negative charge.

In one embodiment, the aromatic hydrocarbon may be Pyrene, Fluoranthene, Biphenyl or Naphthalene.

In the present invention, the concentration of aromatic hydrocarbons may be 0.5 M or more.

In the present invention, the concentration of the aromatic hydrocarbon may be 0.5 to 5 M, 0.5 to 0.5 to 4.5 M, 0.5 to 4.0 M, 0.5 to 3.5 M, 0.5 to 3.0 M, 0.5 to 2.5 M, 0.5 to 2.0, 0.5 to 1.5 M or 0.5 to 1.0 M.

In the present invention, the organic solvent is 1,2-Diethoxyethane, 1,2-Dimethoxyethane, 1,2-Dimethoxypropane, 1,3-Dioxane, 1,3-Dioxepin, 1,3-Dioxolane, 1,3,5-Trioxane, 1,4-Dioxane, 2-Ethoxyethanol, 2-Methyltetrahydrofuran, 2,2,5,5-Tetramethyltetrahydrofuran, Anisole, Benzyl Ether, Butyl Diglyme, Butyl Methyl Ether, Cyclohexyl Methyl Ether, Cyclopentyl Methyl Ether, Di(propylene glycol) methyl ether, Di-tert-butyl ether, Diethylene Glycol, Diethylene Glycol monomethyl ether, Diethyl Ether, Dibutyl Ether, Dimethoxymethane, Dimethyl Ether, Diisopropyl Ether, Diphenyl Ether, Dipropyl Ether, Ethyl Methyl Ether, Ethyl Phenyl Ether, Ethyl tert-Butyl Ether, Ethylene Glycol Diethyl Ether, Ethylene Glycol Monobutyl Ether, Methyl tert-Butyl Ether, Morpholine, Tert-Amyl ethyl ether, Tert-Amyl methyl ether, Tetrahydrofuran, Tetrahydrofuran-D8, It may be an ether-type solvent such as Tetrahydropyran, Tetrahydrofurfuryl Alcohol, Triethylene Glycol Dimethyl Ether, etc.

In the present invention, the organic solvent may be an organic solvent having a dielectric constant of 15 ε _r or less, 14 ε _r or less, 13 ε _r or less, 12 ε _r or less, 11 ε _r or less, or 10 ε _r or less.

In one embodiment, the organic solvent may be 1,2-Dimethoxyethane (DME) or Tetrahydropyran (THP).

In the present invention, the molar ratio of the lithium and the aromatic hydrocarbon in the stripping solution may be 1:1 to 10:1, 1:1 to 8:1, 1:1 to 6:1, 1:1 to 4:1, 1.5:1 to 4:1, 2:1 to 4:1, 2:1 to 3:1, or 2:1 to 2.5:1.

In the method of the present invention, the step of preparing a stripping solution may include the step of adding an aromatic hydrocarbon to an organic solvent and stirring; and the step of adding lithium to the organic solvent to which the aromatic hydrocarbon has been added and stirring.

In the method of the present invention, the impregnation step may be performed for 5 to 120 minutes, 5 to 100 minutes, 5 to 80 minutes, 5 to 60 minutes, 5 to 40 minutes, 5 to 30 minutes, 10 to 30 minutes, or 15 to 30 minutes.

In the method of the present invention, the impregnation step may be performed at 20 to 80°C, 20 to 70°C, 20 to 60°C, 20 to 50°C, or 20 to 40°C.

The method of the present invention may further include a step of removing the waste anode scrap from the stripping solution and stripping it through physical treatment; and a step of drying the stripped waste anode scrap.

In the method of the present invention, “physical treatment” may be ultrasonic treatment, shaking or physical scraping.

In one embodiment, the physical treatment may be to soak the waste cathode scrap taken out of the stripping solution in an organic solvent and then shake it 5 to 15 times, or 10 times.

In the method of the present invention, the drying step may be drying at 20 to 60°C, 30 to 50°C, or 40°C for 3 to 9 hours, 4 to 8 hours, 5 to 7 hours, or 6 hours.

The method of the present invention may further include a step of heat treating the dried waste cathode scrap.

In the method of the present invention, the crystal phase of the cathode material can be recovered by heat-treating the black powder obtained after peeling off the waste cathode scrap.

In the method of the present invention, the heat treatment may be performed by maintaining the temperature at 500 to 600°C for 0.5 to 1.5 hours, and then increasing the temperature to 700 to 800°C for 10 to 20 hours.

In the method of the present invention, the heat treatment may be performed by maintaining the temperature at 500 to 600°C for 0.5 to 1.5 hours, increasing the temperature at a rate of 5 to 10°C/min, and maintaining the temperature at 700 to 800°C for 10 to 20 hours.

In the method of the present invention, the heat treatment may be performed by maintaining the temperature at 550 to 600°C for 1 hour, increasing the temperature at a rate of 5°C/min, and maintaining the temperature at 750 to 800°C for 15 hours.

In the method of the present invention, the heat treatment may be performed by maintaining the temperature at 500°C for 1 hour, increasing the temperature at a rate of 5°C/min, and maintaining the temperature at 780°C for 15 hours.

By heat-treating dried waste cathode scrap, the crystalline phase of the original cathode material can be restored. This heat treatment enables the direct recycling of the cathode.

The method of the present invention may include a step of reusing the stripping solution.

The method of the present invention may include a step of reusing the peeling solution as is.

The method of the present invention may further include a step of adding lithium and reusing the stripping solution when there is discoloration.

The method of the present invention does not require additional processes due to impurities, has a short reaction time, allows the stripping solution to be reused, and because it is a chemical stripping method, it is possible to recover active materials from large quantities of electrodes or waste cathode scrap. For example, by impregnating a large quantity of waste cathode scrap in a large quantity of stripping solution and continuously supplying lithium to the stripping solution, the stripping process can be performed repeatedly and continuously. The stripping step can recover the cathode active material by immersing the large quantity of waste cathode scrap taken out from the stripping solution in an organic solvent and then stirring or ultrasonicating it. Since the subsequent drying and heat treatment steps are also easy to scale up and automate, the method of the present invention enables the recovery of cathode active materials from large quantities of waste cathode scrap.

The present invention provides a composition for stripping waste cathode scrap comprising an organic solvent, an aromatic hydrocarbon, and lithium. The organic solvent, the aromatic hydrocarbon, and the waste cathode scrap are as described above.

Hereinafter, the present invention will be described in detail by way of examples to specifically explain the present invention.

Example

Example 1. Preparation of peeling solution and peeling method

First, Pyrene (CAS 129-00-0), 1,2-Dimethoxyethane (CAS 110-71-4), and Li metal (CAS 7439-93-2) were prepared, and as an electrode to be peeled, NCM811, a positive electrode made of NCM in which nickel, cobalt, and manganese exist in a ratio of 8:1:1, was prepared and its weight was measured. Using pyrene and 1,2-Dimethoxyethane, 2 ml of x M Pyrene in 1,2-Dimethoxyethane were prepared according to the molar concentrations described in Fig. 2, and stirred at 40°C and 200 rpm for 30 minutes. y M Li metal (in 1,2-Dimethoxyethane) was added to the solution according to Fig. 2, and stirred at 40°C and 200 rpm for 2 hours. The above solution was transferred using a dropper to a vial containing the prepared positive electrode and left to stand for 15 minutes. Afterwards, the electrode was transferred to a vial containing 2 ml of 1,2-dimethoxyethane, the vial was capped, and gently shaken 10 times. The electrode after peeling was taken out and dried at 40°C for 6 hours, and then the electrode's weight was measured. The molar concentration of pyrene and the molar concentration ratio of pyrene and lithium metal are shown in Figure 2.

The experimental results show that the weight increase is due to the LMAC solution being impregnated into the electrode or the reaction progressing to the point where Li ⁺ is not stripped during the process of introducing Li + into the electrode. When the concentration of pyrene was 0.25 M, almost no stripping occurred. On the other hand, when the concentration of pyrene was 0.5 M or higher, stripping could be achieved up to 93.71%, and the stripping efficiency was particularly high when the ratio of Li metal to pyrene was 2:1 to 2.5:1. These results are thought to be because the LMAC complex is formed more stably and can more strongly donate Li ⁺ to the anode when the number of electrons that pyrene can accept is 2, which is more stable than the theoretical maximum number of electrons that pyrene can accept, which is 4.

Example 2. Confirmation of peeling efficiency

Example 2-1. Determination of peeling efficiency when using Pyrene/DME or Biphenyl/DME.

The peeling efficiency was compared when Pyrene or Biphenyl was used as an aromatic compound and 1,2-Dimethoxyethane (DME) was used as an organic solvent. The peeling method of Example 1 described above was followed, but Pyrene and Biphenyl were each added to the DME solution at a concentration of 0.5 M, and Li metal was added at a ratio of 4:1 to the aromatic compound, and the peeling times were 10, 20, and 30 minutes, respectively. In addition, the peeling using Pyrene/DME and Biphenyl/DME was performed at room temperature (25°C) and high temperature (40°C), respectively.

As a result, it was confirmed that the stripping efficiency increased as the stripping time increased under all conditions, and in the case of Pyrene/DME, a stripping efficiency of over 90% was achieved when reacted for more than 20 minutes at both room temperature and high temperature. When stripped at high temperature, a high stripping efficiency of 73.6% was confirmed even after 10 minutes of reaction. In the case of Biphenyl/DME, a higher stripping efficiency was observed at room temperature than at high temperature for the same reaction time, and in particular, a high stripping efficiency of 85.3% was observed after reaction for 30 minutes. However, corrosion of the Al current collector was observed after stripping at both room temperature and high temperature, and this was judged to be because the redox potential of the complex formed by Biphenyl and DME is similar to the potential at which Al reacts. In the case of room temperature, the reaction speed of the Al current collector was relatively slow, so the degree of corrosion was less than that at high temperature.

Example 2-2. Determination of peeling efficiency when using naphthalene/DME or fluoranthene/DME.

The peeling efficiency was compared when Naphthalene or Fluoranthene was used as an aromatic compound and 1,2-Dimethoxyethane (DME) was used as an organic solvent. The peeling method of Example 1 described above was followed, but Naphthalene and Fluoranthene were each added to the DME solution at a concentration of 0.5 M, and Li metal was added at a ratio of 4:1 to the aromatic compound, and peeling was performed at a high temperature (40°C) for 10 minutes, 20 minutes, and 30 minutes, respectively.

As a result, it was confirmed that the longer the peeling time under all conditions, the higher the peeling efficiency. In the case of naphthalene/DME, a peeling efficiency of 50.4% was achieved after 30 minutes of reaction. In the case of fluoranthene/DME, a high peeling efficiency of over 90% was achieved after 20 minutes or more of reaction.

The peeling results using Pyrene/DME or Biphenyl/DME under room temperature or high temperature conditions of the previous Example 1-1 were compared (Fig. 5a), and the peeling results using Pyrene/DME, Biphenyl/DME, Naphthalene/DME or Fluoranthene/DME under high temperature conditions of Examples 1-1 and 1-2 were compared (Fig. 5b).

Example 2-3. Determination of peeling efficiency when using Pyrene/DME or Biphenyl/DME.

The peeling efficiency was compared when Fluoranthene was used as an aromatic compound and 1,2-Dimethoxyethane (DME) or Tetrahydropyran (THP) as an organic solvent. The peeling method of Example 1 described above was followed, but Fluoranthene was added to the DME or THP solution to reach a concentration of 0.5 M each, and Li metal was added to the aromatic compound in a ratio of 4:1, and peeling was performed at 40°C for 10 to 60 minutes.

As a result, it can be confirmed that THP, which has a relatively weak solvating power, exhibits a lower peeling efficiency than DME, which has a strong solvating power, at the same time (Fig. 5c). This indicates that the stronger the solvating power, the more efficient the peeling.

Example 3. Confirmation of impurity concentration in the Al collector after peeling

When peeling using the method of the present invention, it was confirmed whether impurities of the Al current collector were generated. The elemental composition of the black powder after peeling was identified through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Sample 1 (#1 (Samp)) is the NCM811 powder, which is the positive active material for the electrode used in this experiment, and Sample 2 (#2 (Samp)) is the black powder obtained when peeled by ultrasonic treatment at an intensity of 60 W for 20 minutes under N-Methyl-2-pyrrolidone (NMP) solvent conditions, using the conventional method of dissolving polyvinylidene fluoride (PVdF) through ultrasonic treatment using NMP. Sample 3 (#3 (Samp)) is the black powder obtained when peeled for 20 minutes using the Pyrene/DME lithium-aromatic complex, which is the peeling method of the present invention.

As can be seen in Table 1 below, the ICP-OES results show that when peeled using NMP, Al was 2.42%, and when using the peeling method of the present invention, Al was 0.0572%, and it can be confirmed that when peeled using NMP, approximately 42.3 times more Al impurities were generated than when using the peeling method of the present invention (Fig. 6, Table 1).

Pristine NCM LMAC NMP Al (%) 0.00843 0.0572 2.42 Li (%) 7.80 11.2 6:30

Example 4. SEM analysis before and after peeling

Example 4-1. Confirmation of particle size before and after peeling

After peeling the waste cathode scrap according to the peeling method of the present invention, the black powder was observed using a scanning electron microscope (SEM). When peeled with pyrene/DME for 20 minutes and biphenyl/DME for 20 minutes, the particle size was observed to be smaller compared to the existing NCM811 powder (Figs. 7a and 7b). The average particle diameter of the existing NCM811 powder was measured to be 14.15 μm, but after peeling with pyrene/DME, the particle diameter decreased to 8.67 μm and after peeling with biphenyl/DME, the particle diameter decreased to 8.44 μm. This is due to the decrease in the size of the secondary particles during the formation of Li ₂ NCM. On the other hand, in the case of peeling using NMP, which is the existing peeling method, it was confirmed that Al current collector impurities were distributed even when ultrasonic treatment was performed at a low output of 60 W (Fig. 7b). Because these Al impurities exist in the form of extremely small particles, their removal is very difficult. In contrast, when the peeling method of the present invention was used, the amount of Al impurities was significantly reduced.

Example 4-2. Recovery of crystal phase of cathode material by heat treatment after peeling

After exfoliation by the method of the present invention, changes in the particles due to heat treatment were confirmed using a scanning electron microscope (SEM). The heat treatment was performed under an O ₂ atmosphere (O ₂ , flow rate: 300 ml/min), maintained at 550°C for 1 hour, then heated up (heating rate: 5°C/min) and maintained at 780°C for 15 hours. The heat-treated black powder samples exfoliated with Pyrene/DME for 20 minutes were observed at magnifications of 2,500, 3,500, and 10,000 times, and compared with the pristine NCM811 powder. It was found that when the black powder obtained after exfoliation by the exfoliation method of the present invention is heat-treated, the crystal phase of the existing cathode material can be restored (Fig. 8). From these results, it can be seen that recycling of the cathode is possible not only through a wet process but also through direct recycling.

Claims (11)

A step of preparing a stripping solution by adding an aromatic hydrocarbon and lithium to an organic solvent; and A method for recovering a positive electrode active material from a waste positive electrode scrap, comprising a step of impregnating the waste positive electrode scrap containing a positive electrode active material in the above-described stripping solution. In claim 1, a step of removing the waste anode scrap from the stripping solution and stripping it through physical treatment; and A method for recovering positive electrode active material from waste positive electrode scrap, further comprising a step of drying the waste positive electrode scrap after peeling is completed. A method for recovering positive electrode active material from waste positive electrode scrap, further comprising a step of heat treating the waste positive electrode scrap after drying is completed, according to claim 2. A method for recovering a cathode active material from waste cathode scrap, wherein the cathode active material according to claim 1 is LiNi _x Co _y Mn _z O ₂ (x+y+z=1). The method of claim 1, wherein the organic solvent is 1,2-Diethoxyethane, 1,2-Dimethoxyethane, 1,2-Dimethoxypropane, 1,3-Dioxane, 1,3-Dioxepin, 1,3-Dioxolane, 1,3,5-Trioxane, 1,4-Dioxane, 2-Ethoxyethanol, 2-Methyltetrahydrofuran, 2,2,5,5-Tetramethyltetrahydrofuran, Anisole, Benzyl Ether, Butyl Diglyme, Butyl Methyl Ether, Cyclohexyl Methyl Ether, Cyclopentyl Methyl Ether, Di(propylene glycol) methyl ether, Di-tert-butyl ether, Diethylene Glycol, Diethylene Glycol monomethyl ether, Diethyl Ether, Dibutyl Ether, Dimethoxymethane, Dimethyl Ether, Diisopropyl Ether, Diphenyl Ether, A method for recovering a cathode active material from waste cathode scrap, wherein the cathode active material is any one selected from the group consisting of Dipropyl Ether, Ethyl Methyl Ether, Ethyl Phenyl Ether, Ethyl tert-Butyl Ether, Ethylene Glycol Diethyl Ether, Ethylene Glycol Monobutyl Ether, Methyl tert-Butyl Ether, Morpholine, Tert-Amyl ethyl ether, Tert-Amyl methyl ether, Tetrahydrofuran, Tetrahydrofuran-D8, Tetrahydropyran, Tetrahydrofurfuryl Alcohol, and Triethylene Glycol Dimethyl Ether. The method of claim 1, wherein the aromatic hydrocarbon is 1,1-Diphenylethylene, 1,4-Di-tert-butyl-2,5-dimethoxybenzene, 2-Fluorobiphenyl, 2-Methylbiphenyl, 3,3'-Dimethylbiphenyl, 3,3',4,4',-Tetramethylbiphenyl, 4,4'-Dimethylbiphenyl, 4-Methylbiphenyl, 5,10-Dihydro-5,10-dimethylphenazine, 9,9-Dimethylfluorene, Acenaphthene, Acetophenone, Acridine, Anthracene, Benzo[a]pyrene, Benzo[b]fluoranthene, Benzimidazole, Benzofuran, Benzothiazole, Benzothiophene, Benzoxazole, Biphenyl, Carbazole, Chrysene, Coumarin, Ethylbenzene, Fluoranthene, Fluorene, Furan, A method for recovering a cathode active material from waste cathode scrap, wherein the cathode active material is any one selected from the group consisting of Hexacene, Imidazole, Indole, Isoindole, Isoquinoline, N,N'-Diphenyl-p-phenylenediamine, Naphthalene, Oxadiazole, Oxazole, Pentacene, Perfluorobenzene, Perylene, Phenanthrene, Phenazine, Phenothiazine, Phenylacetylene, Purine, Pyrazine, Pyridine, Pyrimidine, Pyrene, Pyrrole, Quinoline, Stilbene, Tetracene, Tetrazole, Thiazole, Thiadiazole, Thiophene, Toluene, Triazine, Triphenylene, Xanthine and Xylene. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the concentration of the aromatic hydrocarbon in the stripping solution is 0.5 to 5 M in claim 1. A method for recovering a positive electrode active material from waste positive electrode scrap, wherein the molar ratio of the lithium and the aromatic hydrocarbon in the stripping solution is 1:1 to 10:1 in claim 1. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the impregnating step according to claim 1 is performed for 5 to 120 minutes. A method for recovering positive electrode active material from waste positive electrode scrap, wherein the impregnating step according to claim 1 is performed at a temperature of 20 to 80°C. A composition for stripping waste cathode scrap comprising an organic solvent, an aromatic hydrocarbon and lithium.