Method for recycling positive electrode active material
By using organic solvents to dissolve the binder and separate the positive electrode current collector and composite layer, combined with the crystallization precipitation process, the problems of dust explosion and toxic gas generation are solved, achieving low-cost and high-efficiency recovery of positive electrode active materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LG ENERGY SOLUTION LTD
- Filing Date
- 2025-06-05
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies for recycling positive electrode active materials pose risks such as dust explosions, the generation of toxic gases, and high process costs.
Organic solvents are used to dissolve the binder to separate the positive electrode current collector and the composite layer. The binder is separated through a crystallization precipitation process, avoiding grinding and heat treatment. Organic solvents are used to recover the positive electrode active material.
It improves work safety, avoids the generation of toxic gases, reduces process costs, and increases the recovery rate.
Smart Images
Figure CN122459941A_ABST
Abstract
Description
Technical Field
[0001] This application claims priority to Korean Patent Application No. 10-2024-0074043, filed on June 5, 2024, the disclosure of which is incorporated herein by reference.
[0002] This invention relates to a method for recovering positive electrode active materials from the positive electrode of waste batteries or from positive electrode waste generated during the positive electrode preparation process. Background Technology
[0003] A lithium-ion secondary battery typically comprises a positive electrode containing positive active material, a negative electrode containing negative active material, a separator, and an electrolyte. It is charged and discharged through the insertion and extraction of lithium ions. Lithium-ion secondary batteries have been applied in various fields due to their advantages of high energy density, high electromotive force, and high capacity.
[0004] The positive electrode of a lithium-ion secondary battery is prepared by forming a positive electrode composite layer containing positive electrode active materials, binders, etc., on a positive electrode current collector. The positive electrode active materials include transition metals such as nickel, cobalt, and manganese, as well as lithium. Nickel and cobalt are relatively expensive metals; in particular, cobalt is considered a metal with unstable supply and demand worldwide due to its limited production in certain countries. Therefore, recovering positive electrode active materials from waste positive electrodes or positive electrode waste generated during the manufacturing process and reusing them as raw materials can ensure price competitiveness and generate additional revenue. Recently, research has been conducted on the recovery and regeneration of positive electrode active materials from waste batteries or positive electrode waste generated during battery manufacturing.
[0005] The conventional method involves grinding the positive electrode or positive electrode waste of waste batteries into powder, then performing a pretreatment process to sort and crush the positive electrode composite layer, then removing the binder through heat treatment, and finally adding an acid solution to extract valuable metals.
[0006] However, in the case of mechanical grinding methods, there is a risk of fire and dust explosion when lithium metal contained in micron-sized fine powder comes into contact with moisture. Furthermore, because the positive electrode current collector is also ground during the grinding process, the final recovered powder contains a large amount of material contained in the positive electrode current collector (such as aluminum) as impurities. Therefore, a separate purification process is required to remove impurities from the recovered powder. This leads to a problem of reduced recovery rate of valuable metals due to the loss of valuable metals during the purification process.
[0007] In addition, according to conventional methods, the heat treatment process used to remove the adhesive generates toxic hydrogen fluoride gas, which requires additional gas treatment equipment to handle the hydrogen fluoride gas, thus increasing the process cost.
[0008] Therefore, there is a need to develop a method for efficiently recovering positive electrode active materials with reduced process costs. Summary of the Invention
[0009] [Technical Issues]
[0010] To address the aforementioned problems, this invention aims to provide a method for recycling positive electrode active materials that is environmentally friendly, does not produce toxic gases, provides excellent operational safety, and is relatively low in cost.
[0011] [Technical Solution]
[0012] One aspect of the present invention provides a method for recovering positive electrode active material, the method comprising: a first step of immersing a positive electrode comprising a positive electrode current collector and a positive electrode composite layer in an organic solvent to separate the positive electrode composite layer and the positive electrode current collector, the positive electrode composite layer comprising a positive electrode active material and a binder, the organic solvent being capable of dissolving the binder; a second step of removing the positive electrode current collector to obtain a first processing liquid comprising the positive electrode active material, the binder, and the organic solvent; a third step of removing at least a portion of the organic solvent contained in the first processing liquid; a fourth step of precipitating the binder by adding water to the first processing liquid and separating the precipitated binder to obtain a second processing liquid comprising the positive electrode active material, water, and the organic solvent; a fifth step of separating the positive electrode active material from the second processing liquid to obtain a third processing liquid comprising water and the organic solvent; and a sixth step of removing water from the third processing liquid and recovering the organic solvent.
[0013] At this point, the organic solvent can be, for example, N-methylpyrrolidone, and the first step can be carried out by heating and / or shaking.
[0014] In the first step, the soaking can be carried out for 10 minutes to 200 minutes, preferably 20 minutes to 180 minutes, and more preferably 40 minutes to 180 minutes.
[0015] Meanwhile, in the second step, the adhesive can be adsorbed onto the positive electrode active material to form a precipitate, and in this case, the third step can be performed by removing the supernatant of the first treatment solution.
[0016] Alternatively, the third step can be carried out by filtering the first treatment liquid to selectively remove only the organic solvent.
[0017] Preferably, a third step is performed such that the solid content in the first treatment solution becomes 10% to 95% by weight after the removal of the organic solvent.
[0018] Meanwhile, in the fourth step, water is preferably added in an amount of 5% to 95% of the total volume of the first treatment liquid.
[0019] Next, in the fifth step, the separation of the positive electrode active material from the second treatment solution can be performed by precipitating the positive electrode active material in the second treatment solution and then performing gravity separation, or by filtering the second treatment solution.
[0020] If necessary, after the fifth step, a further step may be included: washing and drying the positive electrode active material separated from the second treatment liquid.
[0021] The sixth step can be carried out by fractional distillation of the third treatment liquid. The organic solvent obtained in the sixth step can be reused in the first step.
[0022] [Beneficial Effects]
[0023] In the method for recycling positive electrode active material of the present invention, since the separation of positive electrode current collector and positive electrode composite layer is carried out by immersing the positive electrode in an organic solvent that can dissolve the adhesive without using a grinding process, dust generation, explosion, etc. can be suppressed, resulting in excellent work safety.
[0024] Furthermore, in the method for recovering positive electrode active materials of the present invention, since the binder is separated by a crystallization precipitation process rather than heat treatment, no toxic hydrogen fluoride gas is generated, which is environmentally friendly.
[0025] Furthermore, in the method for recovering positive electrode active material of the present invention, since at least a portion of the organic solvent is removed from the first treatment liquid after the positive electrode current collector is removed, the reactivity between water and binder is increased, the amount of water used for precipitating the binder can be reduced, and the energy consumed for distillation of water and organic solvent during the fractionation of the third treatment liquid can be reduced.
[0026] Furthermore, the positive electrode active material of the present invention has a low processing cost because it does not require expensive equipment such as grinding equipment or gas processing equipment. Attached Figure Description
[0027] Figure 1 The photograph shows the state of the positive electrode current collector after a certain period of time, removed from the N-methylpyrrolidone solvent that had been impregnated with the positive electrode, without ultrasonic treatment.
[0028] Figure 2 The photograph shows the state of the positive electrode current collector after being removed from the N-methylpyrrolidone solvent that had been impregnated with the positive electrode, following a certain period of time after 20 minutes of ultrasonic irradiation. Detailed Implementation
[0029] The invention will be described in more detail below.
[0030] The method for recovering positive electrode active material of the present invention includes: (1) a first step of immersing a positive electrode comprising a positive electrode current collector and a positive electrode composite layer in an organic solvent to separate the positive electrode composite layer and the positive electrode current collector, the positive electrode composite layer comprising a positive electrode active material and a binder, the organic solvent being capable of dissolving the binder; (2) a second step of removing the positive electrode current collector to obtain a first processing liquid comprising the positive electrode active material, the binder and the organic solvent; (3) a third step of removing at least a portion of the organic solvent contained in the first processing liquid; (4) a fourth step of precipitating the binder by adding water to the first processing liquid and separating the precipitated binder to obtain a second processing liquid comprising the positive electrode active material, water and the organic solvent; (5) a fifth step of separating the positive electrode active material from the second processing liquid to obtain a third processing liquid comprising water and the organic solvent; and (6) a sixth step of removing water from the third processing liquid and recovering the organic solvent.
[0031] (1) First step: Separate the positive current collector
[0032] First, the positive electrode is immersed in an organic solvent that can dissolve the adhesive.
[0033] At this point, the positive electrode can be a positive electrode separated from a waste battery, or positive electrode waste generated during the preparation of the positive electrode.
[0034] The positive electrode includes a positive current collector and a positive electrode composite layer formed on one or both sides of the positive current collector. The positive current collector can be a type of positive current collector commonly used in related technical fields, such as aluminum alloy foil, stainless steel foil, nickel alloy foil, or aluminum or stainless steel foil surface-treated with carbon, nickel, titanium, silver, etc., and is preferably aluminum alloy foil. The positive electrode composite layer can contain a positive electrode active material and a binder, and may also include conductive materials, dispersants, etc., as needed. The positive electrode active material can be a type of positive electrode active material commonly used in related technical fields, such as lithium iron phosphate; lithium cobalt-based oxide; lithium manganese-based oxide; lithium nickel-based composite transition metal oxide, such as lithium nickel-cobalt-manganese oxide, lithium nickel-cobalt-aluminum oxide, and lithium nickel-cobalt-manganese-aluminum oxide, or combinations thereof, and preferably, may include lithium nickel-based composite transition metal oxide.
[0035] The adhesive is used to bond the positive electrode current collector and the positive electrode active material particles, and may include various adhesives commonly used in the relevant technical field, such as polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM or combinations thereof, and preferably polyvinylidene fluoride.
[0036] Meanwhile, the organic solvent is a solvent capable of dissolving the binder contained in the positive electrode composite layer, and may include, for example, N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), isopropanol, etc., and is preferably N-methylpyrrolidone.
[0037] When the positive electrode is immersed in the aforementioned organic solvent, the adhesive is dissolved by the organic solvent, and the adhesion between the positive electrode current collector and the positive electrode active material particles is lost, causing the positive electrode current collector and the positive electrode active material to separate.
[0038] Impregnation can be carried out until the adhesive is fully dissolved, for example, for 40 to 200 minutes, preferably 40 to 180 minutes.
[0039] Furthermore, after impregnation, if necessary, further steps such as applying heat and / or agitation can be performed. Heating the organic solvent can accelerate the dissolution of the adhesive in the organic solvent, and agitation can accelerate the separation of the positive electrode composite layer from the positive electrode current collector, thereby reducing processing time.
[0040] Specifically, the heating step can be performed by heating the organic solvent at 25°C to 80°C, preferably 50°C to 70°C, more preferably 50°C to 60°C, and the oscillation step can be performed by irradiating the organic solvent with ultrasound or by applying bubbles to the organic solvent to generate mechanical oscillation.
[0041] Figure 1 A photograph shows the state of the positive electrode current collector after being removed from an N-methylpyrrolidone solvent impregnated with the positive electrode, following a certain period of time without ultrasonic treatment. Additionally, Figure 2 The photograph shows the state of the positive electrode current collector after being removed from the N-methylpyrrolidone solvent that had been impregnated with the positive electrode, following a certain period of time after 20 minutes of ultrasonic irradiation.
[0042] Reference Figure 1 and Figure 2As can be seen, when immersed for 40 minutes without ultrasonic treatment, the positive electrode composite layer (black powder) hardly separates from the positive electrode current collector. However, when ultrasonic treatment is performed, the positive electrode composite layer (black powder) separates considerably, even during the 40-minute immersion period. This indicates that ultrasonic treatment accelerates the separation of the positive electrode composite layer.
[0043] In the above method, when the positive current collector and the positive composite layer are separated, the operation is safe and there is no dust generation or explosion.
[0044] (2) Second step: Remove the positive current collector
[0045] Once the positive electrode composite layer is fully separated from the positive electrode current collector through the first step, the positive electrode current collector is removed, and a first treatment solution containing positive electrode active material, binder and organic solvent is obtained.
[0046] In the first processing solution, which is the solution obtained after removing the positive electrode current collector, the positive electrode active material and binder may exist in a suspended state in the organic solvent, or the aggregates of the positive electrode active material and binder may exist in a deposited state at the bottom of the first processing solution.
[0047] If the adhesive is completely dissolved in the organic solvent in the first step, the positive electrode active material and the adhesive can exist in the organic solvent in a suspended state. If the adhesive is not completely separated from the positive electrode active material and is adsorbed on the surface of the positive electrode active material particles, the positive electrode active material particles can be adhered together by the adhesive to form aggregates, and thus can be deposited at the bottom of the first treatment liquid in the state of precipitate.
[0048] (3) Third step: Remove organic solvents
[0049] Next, at least a portion of the organic solvent is removed from the first treatment liquid. When at least a portion of the organic solvent is removed from the first treatment liquid, the organic solvent content can be reduced, thereby increasing the reactivity between water and the binder in the fourth step described later, thus reducing the amount of water used to precipitate the binder. Furthermore, correspondingly, in the sixth step described later, the water and organic solvent content in the third treatment liquid can be reduced, thereby reducing the energy consumption for distillation of water and organic solvents during the fractionation process.
[0050] Organic solvents can be removed, for example, by removing the supernatant of the first treatment solution, or by selectively removing the organic solvents through filtration.
[0051] When the positive electrode active material and binder exist in the first treatment solution as precipitates, the organic solvent can be removed by a simple method of removing the supernatant.
[0052] Meanwhile, when the positive electrode active material and binder exist in the first treatment liquid in a suspended state, the organic solvent can be selectively removed by filtration, without removing the positive electrode active material and binder as solid components.
[0053] A third step can be performed to reduce the solids content in the first treatment liquid to 10 to 95% by weight, preferably 40 to 95% by weight, more preferably 60 to 95% by weight, and even more preferably 80 to 95% by weight, after the removal of the organic solvent. When the amount of organic solvent removed is within the above range, the amount of water required for the precipitation of the adhesive in the fourth step described later can be effectively reduced. If the amount of organic solvent removed is too large, there may be a problem that the adhesive separation cannot be carried out smoothly even if water is added in the subsequent process.
[0054] (4) Fourth step: Separate the adhesive
[0055] Next, water is added to the first treatment solution, from which at least some of the organic solvent has been removed. When the adhesive, such as PVDF or PVDF-co-HFP, dissolved in the organic solvent reacts with water, the adhesive can crystallize and precipitate into a solid state.
[0056] At this point, based on the total volume of the first treatment solution, the amount of water added is preferably 5% to 95% by volume, more preferably 10% to 90% by volume, more preferably 40% to 90% by volume, and even more preferably 60% to 90% by volume. When the amount of water added falls within the above range, the precipitation of the adhesive in the first treatment solution can proceed smoothly. If the amount of water added is too small, the amount of unprecipitated adhesive may increase, making it difficult to reuse the organic solvent, and if the amount of water added is too large, a large amount of energy may be consumed to purify the organic solvent in the sixth step described later.
[0057] Once the adhesive has precipitated using the method described above, the precipitated adhesive is separated. At this point, the adhesive can be separated by, for example, removing the adhesive floating on the surface of the solution.
[0058] Once the precipitated binder has been removed as described above, the positive electrode active material, water, and organic solvent remain in the remaining solution. For convenience, the remaining solution containing the positive electrode active material, water, and organic solvent will be referred to as the second treatment solution.
[0059] Meanwhile, the separation of the adhesive can be carried out at least once, for example, 1-10 times, preferably 1-5 times.
[0060] (5) Fifth step: Recover the positive electrode active material
[0061] Next, the positive electrode active material is separated from the second processing solution, and a third processing solution containing water and organic solvent is obtained.
[0062] At this point, the separation of the positive electrode active material can be carried out using various solid-liquid separation methods known in the relevant technical field. For example, a method can be used to deposit the positive electrode active material as a solid phase and then separate the positive electrode active material from the second treatment liquid by gravity separation, or a method can be used to selectively release only the water and organic solvent in the liquid phase from the second treatment liquid by filtration, but the method is not limited to these.
[0063] Additionally, if necessary, after the fifth step, the positive electrode active material separated from the second treatment solution can undergo further post-processing, such as washing, drying, and impurity removal (purification).
[0064] Washing is the removal of impurities from the surface of the positive electrode active material. It can be carried out according to methods for washing positive electrode active materials that are generally known in the relevant technical field, and for example, washing can be carried out by adding the positive electrode active material to water and stirring.
[0065] Drying removes residual organic solvents and water from the positive electrode active material. This can be done, for example, by drying the washed positive electrode active material at 80°C to 140°C, preferably 80°C to 120°C, but the method is not limited to this. The temperature used for drying can be varied depending on the airflow, agitation, partial pressure, etc., of the drying system.
[0066] The positive electrode active material obtained through the above post-processing can be reused as a raw material for batteries, or it can be used to recover valuable metals through acid treatment or other methods.
[0067] (6) Step 6: Separation of organic solvents
[0068] Next, water is removed from the third processed liquid obtained in the fifth step, and the organic solvent is recovered. This step can be performed, for example, by fractional distillation of the third processed liquid. Since water and organic solvents have different boiling points, water and organic solvents can be effectively separated by fractional distillation, and the organic solvent purified by cooling distillation can be recovered. The recovered organic solvent can be reused in the first step. Reusing the organic solvent as described above reduces the consumption of organic solvents, thereby lowering process costs.
Claims
1. A method for recovering positive electrode active materials, comprising: The first step involves immersing a positive electrode containing a positive current collector and a positive electrode composite layer in an organic solvent to separate the positive electrode composite layer and the positive current collector. The positive electrode composite layer contains a positive electrode active material and a binder, and the organic solvent is capable of dissolving the binder. The second step is to remove the positive current collector to obtain a first treatment solution containing the positive active material, the binder, and the organic solvent. The third step is to remove at least a portion of the organic solvent contained in the first treatment solution; The fourth step involves precipitating the adhesive by adding water to a first treatment solution in which at least a portion of the organic solvent has been removed, and separating the precipitated adhesive to obtain a second treatment solution containing the positive electrode active material, water, and the organic solvent. The fifth step involves separating the positive electrode active material from the second treatment solution to obtain a third treatment solution containing water and the organic solvent; and The sixth step involves removing water from the third treatment solution and recovering the organic solvent.
2. The method as described in claim 1, wherein, The organic solvent is N-methylpyrrolidone.
3. The method as described in claim 1, wherein, The first step is carried out by applying heat or vibration, at least one of these methods.
4. The method of claim 1, wherein, In the second step, the adhesive is adsorbed onto the positive electrode active material to form a precipitate.
5. The method of claim 4, wherein, The third step is carried out by removing the supernatant from the first treatment solution.
6. The method of claim 1, wherein, The third step is carried out by filtering the first treatment liquid to selectively remove only the organic solvent.
7. The method of claim 1, wherein, The third step is performed such that the solid content in the first treatment solution becomes 10% to 95% by weight after the removal of the organic solvent.
8. The method of claim 1, wherein, In the fourth step, water is added in amounts ranging from 5% to 95% of volume, based on the total volume of the first treatment solution.
9. The method of claim 1, wherein, In the fifth step, the positive electrode active material is separated from the second treatment solution by precipitating the positive electrode active material in the second treatment solution and then performing gravity separation.
10. The method of claim 1, wherein, In the fifth step, the positive electrode active material is separated from the second processing liquid by filtering the second processing liquid.
11. The method of claim 1, further comprising the steps of washing and drying the positive electrode active material separated from the second treatment liquid after the fifth step.
12. The method of claim 1, wherein, The sixth step is carried out by fractionating the third treatment liquid.
13. The method of claim 1, wherein, The organic solvent obtained in step six is reused in step one.