WO2025178419A1 - Method for recovery of positive electrode material from black powder - Google Patents

Abstract

The present invention relates to a method for environmentally-friendly and effective recovery of a positive electrode material from black powder, the method comprising: a dissolution step of mixing black powder and a basic solution to dissolve a current collector component; a solid-liquid separation step of removing the solvent in which the current collector component is dissolved; and a drying step of drying the separated solid component.

Description

Method for recovering cathode material from black powder

This application claims the benefit of priority from Korean Patent Application No. 10-2024-0026341, filed February 23, 2024, the entire contents of which are incorporated herein by reference.

The present invention relates to a method for recovering a cathode material from black powder.

Batteries that have reached the end of their useful life (EOL (End of Life) batteries) are typically discarded. The process of disposing of batteries can lead to the release of various hazardous substances and the loss of valuable metals. To address these issues, research is underway into technologies for recycling end-of-life batteries. Conventional methods involve shredding or melting end-of-life batteries and then immersing them in an acid solution to recover valuable metals.

Meanwhile, cathode material waste is generated in various forms during the battery manufacturing process. During the battery manufacturing process, electrodes are inspected in various ways. Electrodes found to be defective are typically discarded. Discarded cathodes are crushed or melted, then immersed in an acid solution to recover valuable metals.

The previously described method of recovering valuable metals by immersing scrap batteries or electrodes in acid solutions has limitations, such as the large amount of wastewater discharged during the process. Therefore, there is a need for an environmentally friendly and efficient technology for regenerating or recycling cathode materials.

In order to solve the problems of the prior art as described above, the present invention aims to provide a method for effectively recovering a cathode material from an electrode, specifically, a black powder.

In order to solve the above-mentioned problem, in one embodiment, a method for recovering a cathode material according to the present invention is a method for recovering a cathode material from black powder.

Specifically, the above cathode material recovery method includes a dissolution step of dissolving a current collector component by mixing black powder and an alkaline solution; a solid-liquid separation step of removing a solvent in which the current collector component is dissolved; and a drying step of drying the separated solid component.

For example, the basic solution includes at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia water (NH ₄ OH), and magnesium hydroxide (Mg(OH) ₂ ).

In one embodiment, in the dissolution step, the current collector component comprises aluminum (Al). In this case, for example, the alkaline solution is a sodium hydroxide (NaOH) aqueous solution. Through this, the present invention can dissolve the current collector component according to the following reaction scheme 1.

[Reaction Formula 1]

2Al + 2NaOH + 2H ₂ O → 2NaAlO ₂ + 3H ₂

In another embodiment, the dissolving step is performed at a temperature of 10 to 100°C for 1 to 10 hours.

In another embodiment, the dissolution step is performed by applying at least one of stirring treatment and ultrasonic treatment while the black powder is immersed in a basic solution.

The present invention may include, after the solid-liquid separation step, a washing step of washing the separated solid component with a washing solvent. For example, the washing solvent is water, specifically distilled water.

Specifically, the present invention additionally performs a solid-liquid separation step after the washing step.

In one embodiment, the drying step is performed at a temperature of 100 to 400°C for 1 to 30 hours.

For example, the black powder is a cathode fragment. As another example, the cathode is a cathode of a lithium secondary battery.

The present invention can effectively and environmentally recover cathode material from black powder.

Figure 1 is a schematic diagram showing the cross-sectional structure of a cylindrical battery.

Figure 2 is a flowchart illustrating a process for recovering a cathode material from black powder according to one embodiment of the present invention.

Figure 3 is a flowchart illustrating a process for recovering a cathode material from black powder according to another embodiment of the present invention.

The present invention can be modified in various ways and has many embodiments, and specific embodiments will be described in detail in the detailed description.

However, this is not intended to limit the present invention to a specific embodiment, but should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

In the present invention, "black powder" refers to electrode fragments, specifically, positive electrode fragments. Specifically, the black powder includes a state in which a positive electrode, which is a structure in which an electrode active material layer is formed on an electrode current collector, is fragmented. The black powder may be, for example, positive electrode fragments. In this case, the black powder is a mixed form of one or more components selected from the group consisting of Al, Li, Ni, Co, Mn, Fe, and C. The composition of the black powder may vary depending on the type of positive electrode active material.

In the present invention, it should be understood that terms such as “include” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

Hereinafter, the present invention will be described in more detail.

The method for recovering a cathode material according to the present invention comprises a dissolution step for dissolving a current collector component by mixing black powder and an alkaline solution; a solid-liquid separation step for removing the solvent in which the current collector component has been dissolved; and a drying step for drying the separated solid component. The dissolution step involves immersing the black powder in an alkaline solution to dissolve Al, which is a current collector component. By removing the current collector component from the black powder through this process, only the active material and conductive material components remain.

Specifically, the basic solution includes at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia water (NH ₄ OH), and magnesium hydroxide (Mg(OH) ₂ ). More specifically, the basic solution is sodium hydroxide (NaOH), and for example, the basic solution is a sodium hydroxide aqueous solution.

In one example, in the dissolution step, the current collector component includes aluminum (Al), and the basic solution is a sodium hydroxide (NaOH) aqueous solution. For example, 1 kg of black powder is immersed in 10 to 30 L of a sodium hydroxide aqueous solution. At this time, the concentration of the sodium hydroxide aqueous solution can be controlled to a level of 1 to 4 molar.

The above dissolution step dissolves aluminum (Al), which is a current collector component, according to the following reaction scheme 1.

[Reaction Formula 1]

2Al + 2NaOH + 2H ₂ O → 2NaAlO ₂ + 3H ₂

The above dissolution step can be performed at a temperature of 10 to 100°C for 1 to 10 hours. Specifically, the dissolution step can be performed at a temperature of 15 to 60°C for 3 to 6 hours. The dissolution step can be performed at room temperature (20 to 30°C), but can be performed at 30 to 60°C to increase reaction efficiency.

In addition, the above dissolution step can be performed by applying at least one of stirring treatment and ultrasonic treatment while the black powder is immersed in a basic solution.

The above stirring or ultrasonic treatment can be used to increase the reaction efficiency and speed up the process. The ultrasonic application can be performed by applying ultrasonic waves in the range of 20 to 200 KHz. Specifically, the conditions for applying the ultrasonic waves can be performed under the conditions of a frequency of 120 to 200 kHz and an output of 200 to 600 W. In addition, the ultrasonic application time can be continuously applied for 1 to 10 hours, but also includes cases where ultrasonic waves are applied intermittently or periodically for a shorter period of time. For example, the ultrasonic application can be performed by applying the ultrasonic waves for 5 to 60 minutes, resting for 5 to 60 minutes, and then applying the ultrasonic waves again.

After the above dissolution step, a solid-liquid separation step is performed to remove the solvent in which the current collector component is dissolved. The aluminum (Al) component is dissolved in the form of NaAlO ₂ in an alkaline aqueous solution, and the aluminum (Al) component is removed through solid-liquid separation.

In one example, after the solid-liquid separation step, a washing step is included for washing the separated solid component with a washing solvent. The washing solvent may be water, and specifically, distilled water may be used.

Following the above washing step, a solid-liquid separation step may be additionally performed. The washing step removes aluminum (Al) and sodium (Na) components remaining within the solid component. In addition, the additional solid-liquid separation step sufficiently removes foreign substances, including aluminum (Al) and sodium (Na) components remaining within the solid component.

After removing the aluminum (Al) component from the black powder, it undergoes a drying step. The drying step can be performed at temperatures ranging from 100 to 400°C for 1 to 30 hours. The drying step can more effectively remove any remaining solution or solvent components through vacuum drying. Alternatively, the drying step can be performed through hot air drying.

Specifically, the black powder may be anode fragments. In one example, the component obtained through the drying step is a mixture of a cathode active material and a conductive material. The cathode active material and the conductive material can be separated through an additional process. Alternatively, a method of reusing the cathode active material and the conductive material without separating them is also possible. The process of separating the cathode active material and the conductive material can be performed by a physical method. For example, particle size separation using a sieve can be used to separate the components. This method physically removes the conductive material particles by utilizing the difference in particle size between the active material particles and the conductive material particles.

The above black powder can be obtained from a secondary battery whose lifespan has expired or from process waste generated during the process of manufacturing a secondary battery.

When the above black powder is obtained from a secondary battery whose lifespan has expired, the secondary battery is discharged by immersing it in salt water or the like. The outer case of the discharged secondary battery is removed. The outer case can be removed using a punching press or a water jet cutter. The electrode assembly is extracted from the secondary battery from which the outer case has been removed, and the electrode assembly is separated into a positive electrode, a negative electrode, and a separator. The separated positive electrode can be crushed to obtain a positive electrode black powder.

Additionally, if the black powder is obtained from process waste, it is because the electrode or battery is determined to be defective during the secondary battery manufacturing process. For example, if the positive electrode is determined to be defective during the manufacturing process, the positive electrode is shredded to produce black powder. Furthermore, if the battery is determined to be defective during the manufacturing process, the positive electrode is separated through a process of disassembling the outer case. The separated positive electrode is then shredded to produce black powder.

For example, electrode defect determination includes a method of inspecting the presence of surface cracks through vision inspection and a method of inspecting the loading amount through weight measurement.

For another example, battery capacity determination includes inspection of weld defects between electrode tabs and electrode leads (including vision inspection, low voltage inspection, or ultrasonic application inspection), initial charge/discharge efficiency inspection, and battery life/efficiency inspection.

The present invention discloses a technology for recovering a cathode material from a black powder obtained as process waste generated in the process of manufacturing a secondary battery or a secondary battery whose lifespan has expired.

The secondary battery is, specifically, a lithium secondary battery, and specifically, a medium- to large-sized lithium secondary battery. The lithium secondary battery may include an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a non-aqueous electrolyte that impregnates the electrode assembly; and an external case that houses the electrode assembly and the non-aqueous electrolyte.

The above positive electrode includes a positive electrode active material layer formed on a positive electrode current collector. The positive electrode active material layer includes a positive electrode active material, a binder, a conductive agent, and the like, and may further include a positive electrode additive commonly used in the art, if necessary.

The positive electrode active material may be a lithium-containing oxide, which may be the same or different. As the lithium-containing oxide, a lithium-containing transition metal oxide may be used.

For example, the lithium-containing transition metal oxides are Li _x CoO ₂ (0.5<x<1.3), Li _x NiO ₂ (0.5<x<1.3), Li _x MnO ₂ (0.5<x<1.3), Li _x Mn ₂ O ₄ (0.5<x<1.3), Li _x (Ni _a Co _b Mn _c )O ₂ (0.5<x<1.3, 0<a<1, 0<b<1, 0<c<1, a+b+c=1), Li _x Ni _1-y Co _y O ₂ (0.5<x<1.3, 0<y<1), Li _x Co _1-y Mn _y O ₂ (0.5<x<1.3, 0≤y<1), Li _x Ni _1-y Mn _y O ₂ (0.5<x<1.3, O≤y<1), Li _x (Ni _a Co _b Mn _c )O ₄ (0.5<x<1.3, 0<a<2, 0<b<2, 0<c<2, a+b+c=2), Li _x Mn _2-z Ni _z O ₄ (0.5<x<1.3, 0<z<2), Li _x Mn _2-z Co _z O ₄ (0.5<x<1.3, 0<z<2), Li _x CoPO 4 (0.5<x<1.3), and Li _x FePO ₄ (0.5<x<1.3) may be any one selected from the group consisting of Li x Mn 2-z Ni z O ₄ (0.5<x<1.3, 0<z<2), or a mixture of two or more thereof, and the lithium-containing transition metal oxide may be coated with a metal such as aluminum (Al) or a metal oxide. In addition to the lithium-containing transition metal oxide, sulfide, selenide, and halide may also be used.

The cathode according to the present invention can be applied to various types of lithium secondary batteries, but is preferably utilized in high-output batteries. The cathode active material layer of the present invention is applied to a high-nickel content (High-Ni) NCM battery.

In a specific example, the positive electrode active material layer according to the present invention includes an active material component having a structure represented by the following chemical formula 1.

[Chemical Formula 1]

Li _x (Ni _a Co _b Mn _c )O ₂

(0.5<x<1.3, 0.3<a<1, 0<b<0.5, 0<c<0.5, a+b+c=1)

In the above chemical formula 1, the a value is greater than 0.3, 0.6 or more, and specifically, 0.8 or more. In the above chemical formula 1, when the a value increases, the b value and/or the c value decrease within a range satisfying the above chemical formula 1. Through this, the positive electrode for a lithium secondary battery according to the present invention is applied to a high-nickel content (High-Ni)-based NCM secondary battery. The NCM secondary battery is, for example, an NCM 622 or NCM 811 lithium secondary battery.

The current collector used for the positive electrode may be any metal with high conductivity, to which the positive electrode active material slurry can readily adhere, and which is non-reactive within the voltage range of the electrochemical device. Non-limiting examples of current collectors for the positive electrode include foils made of aluminum, nickel, or a combination thereof.

The above-mentioned positive electrode active material may be included in the positive electrode active material layer in a range of 94.0 to 98.5 wt%. When the content of the positive electrode active material satisfies the above range, it is advantageous in terms of manufacturing a high-capacity battery and providing sufficient positive electrode conductivity and inter-electrode material adhesion.

Any binder commonly used in the art can be used without limitation. For example, various types of binders can be used, such as poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-co-HFP, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, styrene-butadiene rubber (SBR), and carboxyl methyl cellulose (CMC).

The above negative electrode includes a negative electrode active material layer formed on a negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a binder, and a conductive agent, and may further include a negative electrode additive commonly used in the art, if necessary.

The negative active material may include carbon, lithium metal, silicon, or tin. When carbon is used as the negative active material, both low-crystalline carbon and high-crystalline carbon can be used. Representative low-crystalline carbons include soft carbon and hard carbon, and representative high-crystalline carbons include natural graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature calcined carbons such as petroleum or coal tar pitch derived cokes.

Non-limiting examples of current collectors used in the above negative electrode include foils made of copper, gold, nickel, or copper alloys, or combinations thereof.

Additionally, the cathode may include a conductive material and a binder commonly used in the field.

In the present invention, the separator may be any porous substrate used in a lithium secondary battery, and for example, a polyolefin porous membrane or non-woven fabric may be used, but is not particularly limited thereto.

Examples of the above polyolefin porous membrane include a membrane formed from a single or mixed polymer of polyolefin polymers such as polyethylene, polypropylene, polybutylene, polypentene, etc., such as high-density polyethylene, linear low-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene.

The above nonwoven fabric may include, in addition to polyolefin-based nonwoven fabrics, nonwoven fabrics formed from polymers such as polyethylene terephthalate, polybutylene terephthalate, polyester, polyacetal, polyamide, polycarbonate, polyimide, polyetheretherketone, polyethersulfone, polyphenyleneoxide, polyphenylenesulfide, and polyethylenenaphthalene, either singly or in combination. The structure of the nonwoven fabric may be a spunbond nonwoven fabric composed of long fibers or a meltblown nonwoven fabric.

The thickness of the porous substrate is not particularly limited, but may be 5 to 50 μm, and the pore size and pore content present in the porous substrate are also not particularly limited, but may be 0.01 to 50 μm and 10 to 95%, respectively.

Meanwhile, in order to improve the mechanical strength of the separator composed of the porous substrate and to suppress short circuits between the anode and cathode, a porous coating layer including inorganic particles and a binder polymer may be further included on at least one side of the porous substrate.

In the present invention, the non-aqueous electrolyte may include an organic solvent and an electrolyte salt, and the electrolyte salt is a lithium salt. The lithium salt may be any of those commonly used in non-aqueous electrolytes for lithium secondary batteries without limitation. For example, the anions of the lithium salt include F ^- , Cl ^- , Br ^- , I ^- , NO ₃ ^- , N(CN) ₂ ^- , BF ₄ ^- , ClO ₄ ^- , PF ₆ ^- , (CF ₃ ) ₂ PF ₄ ^- , (CF ₃ ) ₃ PF ₃ ^- , (CF ₃ ) ₄ PF ₂ ^- , (CF ₃ ) ₅ PF ^- , (CF ₃ ) ₆ P ^- , CF ₃ SO ₃ ^- , CF ₃ CF ₂ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (FSO ₂ ) ₂ N ^- , CF ₃ CF ₂ (CF ₃ ) ₂ CO ^- , (CF ₃ SO ₂ ) ₂ CH ^- , (SF ₅ ) ₃ C ^- , CF ₃ (CF ₂ ) It may include one or two or more selected from the group consisting of ₇ SO ₃ ^- , CF ₃ CO ₂ ^- , CH ₃ CO ₂ ^- , SCN ^- and (CF ₃ CF ₂ SO ₂ ) ₂ N ^- .

As the organic solvent included in the non-aqueous electrolyte described above, those commonly used in non-aqueous electrolytes for lithium secondary batteries can be used without limitation, and for example, ethers, esters, amides, linear carbonates, cyclic carbonates, etc. can be used singly or in combination of two or more. Among these, representative examples include carbonate compounds that are cyclic carbonates, linear carbonates, or mixtures thereof.

The injection of the above non-aqueous electrolyte may be performed at an appropriate stage during the electrochemical device manufacturing process, depending on the final product's manufacturing process and required physical properties. That is, it may be applied prior to electrochemical device assembly or at the final stage of electrochemical device assembly.

Hereinafter, the present invention will be described in more detail with reference to drawings and the like. However, the drawings and the like are merely illustrative of the present invention, and the contents of the present invention are not limited thereto.

Fig. 1 is a schematic diagram showing the cross-sectional structure of a cylindrical battery. Referring to Fig. 1, the cylindrical battery includes an electrode assembly having a structure in which a positive electrode (10), a negative electrode (20), and a separator (31, 32) are alternately laminated and wound in a cylindrical shape. A positive electrode tab (11) is formed on the upper end of the core of the electrode assembly, and a negative electrode tab (21) is formed on one side of the lower end of the electrode assembly. The electrode assembly is housed in a cylindrical battery case (40), and sealed by covering the upper end with a positive electrode cap while an electrolyte is injected.

Figure 2 is a flowchart illustrating a cathode material recovery process according to one embodiment of the present invention. Referring to Figure 2, a dissolution step (S110) is performed in which black powder is immersed in a sodium hydroxide (NaOH) aqueous solution. In this dissolution step (S110), aluminum (Al), a current collector component, is dissolved.

Specifically, in the dissolution step (S110), 1 kg of black powder is immersed in 20 L of a sodium hydroxide aqueous solution. At this time, the concentration of the sodium hydroxide aqueous solution can be controlled to a level of 2 to 3 mol. In addition, in the dissolution step (S110), ultrasonic waves are applied while the black powder is immersed in the sodium hydroxide solution. The ultrasonic wave application is performed by applying ultrasonic waves in the range of 120 to 200 KHz at an output condition of 100 to 200 W. In addition, the dissolution step (S110) is performed at a temperature of 20 to 30°C for 5 hours.

Then, a solid-liquid separation step (S120) is performed. In the solid-liquid separation step (S120), a solution in which aluminum (Al) is dissolved is removed, and a solid-state cathode material is obtained.

After the above solid-liquid separation step (S120), a distilled water washing step (S130) and a solid-liquid separation step (S140) may be sequentially performed. This is to sufficiently remove aluminum (Al) and sodium (Na), etc. remaining in the solid-state cathode material.

Finally, the cathode material is recovered through a drying step (S250). The drying step (S150) can be performed in a vacuum drying chamber connected to a vacuum pump, and is performed at 200 to 300°C for 9 to 10 hours.

Figure 3 is a flowchart illustrating a cathode material recovery process according to another embodiment of the present invention. Referring to Figure 3, a dissolution step (S210) is performed in which black powder is immersed in a sodium hydroxide (NaOH) aqueous solution. Specifically, in the dissolution step (S210), 1 kg of black powder is immersed in a 20 L sodium hydroxide aqueous solution and continuously stirred. The dissolution step (S210) is performed at a temperature of 50 to 60°C for 4 to 5 hours.

Then, the solid-liquid separation step (S220), the distilled water washing step (S230), and the additional solid-liquid separation step (S240) are sequentially performed. Through this, aluminum (Al) and sodium (Na), etc. remaining in the solid-state cathode material are sufficiently removed.

Finally, the cathode material is recovered through a drying step (S250). The drying step (S250) is performed for 6 to 8 hours while supplying hot air at a temperature of 200 to 300°C.

Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the present invention can be made without departing from the spirit and technical scope of the present invention as set forth in the claims to be described below.

Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the patent claims.

[Explanation of symbols]

10: Bipolar

11: Positive tab

20: Cathode

21: Negative tab

31, 32: Membrane

40: Battery case

Claims (10)

A dissolution step in which the current collector component is dissolved by mixing black powder and an alkaline solution; A solid-liquid separation step for removing the solvent in which the entire collector component is dissolved; and A method for recovering a cathode material, comprising a drying step of drying a separated solid component. In the first paragraph, A method for recovering a cathode material, characterized in that the above basic solution contains at least one of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca(OH) ₂ ), ammonia water (NH ₄ OH), and magnesium hydroxide (Mg(OH) ₂ ). In the first paragraph, In the above dissolution step, The entire body component contains aluminum (Al). The basic solution is an aqueous solution of sodium hydroxide (NaOH), A method for recovering a cathode material characterized by dissolving and treating a current collector component according to the following reaction scheme 1: [Reaction Formula 1] 2Al + 2NaOH + 2H ₂ O → 2NaAlO ₂ + 3H ₂ . In the first paragraph, The above dissolution step is, A method for recovering a cathode material, characterized in that it is performed at a temperature of 10 to 100°C for 1 to 10 hours. In the first paragraph, The above dissolution step is, A method for recovering a cathode material, characterized in that at least one of stirring treatment and ultrasonic treatment is applied while the black powder is immersed in an alkaline solution. In the first paragraph, After the above high-liquid separation step, A method for recovering a cathode material further comprising a washing step of washing the separated solid component with a washing solvent. In paragraph 6, A method for recovering a cathode material, characterized in that the washing solvent is water. In paragraph 6, A method for recovering a cathode material, characterized in that a solid-liquid separation step is additionally performed after a washing step. In the first paragraph, The above drying step is, A method for recovering cathode material, characterized in that it is performed under conditions of 100 to 400°C for 1 to 30 hours. In the first paragraph, A method for recovering cathode material, characterized in that the above black powder is cathode fragments.