Electrode separation method and separation system

Abstract

In the electrode separation method, an electrode including an electrode current collector and an electrode active material layer, and a counter electrode portion electrically connected to the electrode are immersed in a conductive solution. An electrical signal is applied. Separation efficiency can be improved by applying an electrical signal. In addition, the recycling efficiency of the electrode active material can be improved.

Description

Technical Field

[0001] This invention relates to an electrode separation method and separation system. Background Technology

[0002] Rechargeable batteries are batteries that can be repeatedly charged and discharged. With the development of the information communication and display industries, rechargeable batteries are widely used as power sources for portable electronic communication devices such as portable cameras, mobile phones, and laptops. In addition, in recent years, battery packs including rechargeable batteries have been developed for use as power sources for environmentally friendly vehicles such as electric vehicles.

[0003] A lithium secondary battery may include an electrode assembly and an electrolyte impregnating the electrode assembly, the electrode assembly comprising a positive electrode, a negative electrode, and a separator. Furthermore, the lithium secondary battery may include an outer packaging material (e.g., a pouch form) housing the electrode assembly and the electrolyte. Lithium metal oxide may be used as the positive electrode active material. The lithium metal oxide may contain transition metals such as nickel, cobalt, and manganese.

[0004] Due to the high manufacturing costs and environmental concerns associated with the aforementioned expensive precious metals, electrode separation methods are being researched. For example, the positive electrode current collector and the positive electrode active material layer can be separated from the positive electrode, and the metal can be recovered by acid treatment of the positive electrode active material layer. Although sodium hydroxide solution can be used to separate the positive electrode current collector and the positive electrode active material layer, during the separation process, metals (e.g., aluminum) contained in the positive electrode current collector remain on the surface of the positive electrode active material, and these residual metals may act as impurities during the reuse of the positive electrode active material. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] One technical problem of the present invention is to provide an electrode separation method with improved efficiency.

[0007] One technical problem of the present invention is to provide an electrode separation system with improved efficiency.

[0008] (II) Technical Solution

[0009] According to an embodiment of the present invention, an electrode comprising an electrode current collector and an electrode active material layer, and a counter electrode portion electrically connected to the electrode, are immersed in a conductive solution. An electrical signal is then applied.

[0010] According to an exemplary embodiment, during the step of applying the electrical signal, gas can be generated between the electrode current collector and the electrode active material layer.

[0011] According to an exemplary embodiment, a DC signal may be applied in the step of applying the electrical signal.

[0012] According to an exemplary embodiment, in the step of applying an electrical signal, an electrical signal may be applied to make the current value from 0.01A to 8A.

[0013] According to an exemplary embodiment, the conductive solution may contain an aqueous solvent.

[0014] According to an exemplary embodiment, the conductive solution may contain a transition metal.

[0015] According to an exemplary embodiment, the transition metal may include one or more of nickel, cobalt, and manganese.

[0016] According to an exemplary embodiment, the transition metal may include nickel, and the number of moles of nickel in the total number of moles of the transition metal may be from 0.2 to 0.9.

[0017] According to an exemplary embodiment, the concentration of the transition metal in the conductive solution can be from 0.2M to 1.5M.

[0018] According to an exemplary embodiment, the electrode can be moved by a moving part.

[0019] According to an exemplary embodiment, the electrode and the counter electrode can be separated by a separation portion.

[0020] According to an exemplary embodiment, the electrode can be obtained by heat-treating waste lithium secondary batteries at a temperature below 500°C.

[0021] According to an exemplary embodiment, the electrical conductivity of the counter electrode can be 1 S / m or higher.

[0022] An electrode separation system according to an exemplary embodiment includes: an electrode portion including an electrode current collector and an electrode active material layer; a counter electrode portion electrically connected to the electrode portion; a reaction portion for partially immersing the electrode portion and the counter electrode portion in a conductive solution; and an electrical signal application portion for applying an electrical signal.

[0023] (III) Beneficial Effects

[0024] According to an embodiment of the present invention, the electrode separation method involves immersing an electrode comprising an electrode current collector and an electrode active material layer, as well as a counter electrode portion electrically connected to the electrode, in a conductive solution and applying an electrical signal. Therefore, the electrodes can be separated in a short time with high energy efficiency.

[0025] In some implementations, a DC signal can be applied as the electrical signal. Therefore, the amount of metal leached from the electrode current collector can be reduced, thereby reducing the content of impurities in the recovered electrode active material during reuse. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating an electrode separation method according to an exemplary embodiment.

[0027] Figures 2 to 4 This is a schematic diagram illustrating an electrode separation system according to an exemplary embodiment. Detailed Implementation

[0028] Embodiments of the present invention provide a method for separating an electrode comprising an electrode current collector and an electrode active material layer. Furthermore, a system for separating the electrode is provided.

[0029] The accompanying drawings and embodiments in this specification serve to further understand the technical ideas disclosed herein. Therefore, the technical ideas of this invention should not be construed as being limited to the contents described in the drawings and embodiments.

[0030] Figure 1 This is a schematic process diagram illustrating an electrode separation method according to an exemplary embodiment.

[0031] Reference Figure 1 Electrodes, including electrode current collectors and electrode active material layers, as well as counter electrodes, can be prepared (e.g., S10 process).

[0032] The electrode includes a positive electrode and / or a negative electrode. For example, the electrode can be either a positive electrode or a negative electrode.

[0033] The counter electrode can refer to an electrode with the opposite electrical polarity to the electrode. For example, when the electrode is positive, the counter electrode can be negative. Conversely, when the electrode is negative, the counter electrode can be positive.

[0034] According to an exemplary implementation, the electrode may be prepared from a lithium secondary battery.

[0035] The lithium secondary battery may include an electrode assembly, which includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrodes. For example, the lithium secondary battery may include: an NCM-based battery containing nickel, manganese, and cobalt; an NCMA-based battery containing nickel, cobalt, manganese, and aluminum; an LFP-based battery containing lithium, iron, and phosphoric acid; an LCO-based battery containing lithium and cobalt, etc.

[0036] According to an exemplary embodiment, the electrode current collector and the electrode active material layer may exist in a state of direct contact with each other. For example, the electrode may include an electrode current collector and an electrode active material layer formed on one or both sides of the electrode current collector.

[0037] According to an exemplary embodiment, the electrode may be a positive electrode. For example, the electrode may include a positive current collector and a layer of positive active material disposed on at least one side of the positive current collector.

[0038] The positive electrode current collector may include stainless steel, nickel, aluminum, titanium, or alloys thereof. The positive electrode current collector may also include aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver.

[0039] The positive electrode active material layer may contain a positive electrode active material. The positive electrode active material layer may also contain a conductive material and a binder.

[0040] The positive electrode active material may contain compounds that enable reversible insertion and extraction of lithium ions.

[0041] According to an exemplary embodiment, the positive electrode active material may comprise a lithium-nickel metal oxide. The lithium-nickel metal oxide may further comprise at least one of cobalt (Co), manganese (Mn), and aluminum (Al).

[0042] In some embodiments, the positive electrode active material or the lithium-nickel metal oxide may include a layered structure or a crystal structure represented by the following chemical formula 1.

[0043] [Chemical Formula 1]

[0044] Li x Ni a M b O 2+z

[0045] In chemical formula 1, the values ​​can be 0.9≤x≤1.2, 0.6≤a≤0.99, 0.01≤b≤0.4, and -0.5≤z≤0.1. As mentioned above, M can contain Co, Mn, and / or Al.

[0046] The chemical structure represented by Formula 1 indicates the bonding relationships contained in the layered or crystalline structure of the positive electrode active material, and does not exclude other additional elements. For example, M may contain Co and / or Mn, and Co and Mn may be provided together with Ni as the main active element of the positive electrode active material. Formula 1 is provided to represent the bonding relationships of the main active elements, and it should be understood that Formula 1 includes the introduction and substitution of additional elements.

[0047] In one embodiment, in addition to the primary active element, auxiliary elements may be further included to enhance the chemical stability of the positive electrode active material or the layered / crystal structure. These auxiliary elements may be incorporated into the layered / crystal structure and form bonds; this should be understood to also include the chemical structures represented by Formula 1.

[0048] The auxiliary element may include at least one of, for example, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Al, Ga, C, Si, Sn, Sr, Ba, Ra, P, or Zr. The auxiliary element may function as an auxiliary active element, working with Co or Mn to enhance the capacity / power activity of the positive electrode active material; for example, Al.

[0049] In some embodiments, the positive electrode active material may further include lithium cobalt oxide-based active material, lithium manganese oxide-based active material, lithium nickel oxide-based active material, or lithium iron phosphate (LFP)-based active material (e.g., LiFePO4).

[0050] In some embodiments, the positive electrode active material may further include manganese-rich (Mn-rich) based active material, lithium-rich layered oxide (LLO) / over-lithiated oxide (OLO) based active material, and cobalt-less based active material.

[0051] The adhesive may include polyvinylidene fluoride (PVDF), vinylidene fluoride-co-hexafluoropropylene copolymer (poly(vinylidene fluoride-co-hexafluoropropylene)), polyacrylonitrile, polymethyl methacrylate, nitrile rubber (NBR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), etc. In one embodiment, the PVDF-based adhesive can be used as a positive electrode adhesive.

[0052] The conductive material can be added to enhance the conductivity of the positive electrode active material layer and / or the mobility of lithium ions or electrons. For example, the conductive material may include carbon-based conductive materials such as graphite, carbon black, acetylene black, Ketjen black, graphene, carbon nanotubes, vapor-grown carbon fiber (VGCF), and carbon fiber, and / or metal-based conductive materials including perovskite materials such as tin, tin oxide, titanium oxide, LaSrCoO3, and LaSrMnO3.

[0053] According to an exemplary embodiment, the positive electrode can be a positive electrode separated from a waste lithium secondary battery. For example, the positive electrode can be obtained by physically separating the separator and the negative electrode from the waste lithium secondary battery.

[0054] According to an exemplary embodiment, the positive electrode may include heat-treated waste positive electrode material.

[0055] According to an exemplary embodiment, the positive electrode can be prepared by heat-treating a spent lithium-ion secondary battery at a temperature below 500°C. For example, the separator and negative electrode of the spent lithium-ion secondary battery can be separated and heat-treated at a temperature below 500°C, 300°C to 500°C, or 350°C to 450°C to remove the binder and conductive material contained in the positive electrode. The heat-treated positive electrode may be substantially binder-free.

[0056] By using a heat-treated positive electrode, the positive electrode current collector and the positive electrode active material layer can be separated more quickly by applying the following electrical signal.

[0057] In some embodiments, the electrode can be a negative electrode. For example, the negative electrode can be a negative electrode separated from a waste lithium secondary battery. In this case, the counter electrode can be a positive electrode.

[0058] The negative electrode may include a negative electrode current collector (e.g., copper (Cu)) and a negative electrode active material layer.

[0059] For example, the negative electrode active material can be any material known in the art that can adsorb and desorb lithium ions, without particular limitation. For example, the negative electrode active material may include carbon-based materials such as crystalline carbon, amorphous carbon, carbon composites, and carbon fibers, lithium alloys, silicon (Si)-based compounds, or tin.

[0060] According to an exemplary embodiment, the electrode can be a working electrode. For example, the electrode active material contained in the electrode active material layer can act as a catalyst, thereby enabling electrochemical reactions to occur on the electrode.

[0061] According to an exemplary embodiment, the counter electrode may include a material that can be electrically connected to the electrode and form a current flow. For example, the counter electrode may include nickel, copper, aluminum, silver, silicon, their oxides, their alloys, etc.

[0062] According to an exemplary embodiment, the counter electrode may include a nickel metal electrode or a lithium metal electrode.

[0063] According to an exemplary embodiment, the conductivity of the counter electrode can be 1 S / m or higher.

[0064] In some embodiments, the conductivity of the counter electrode can be greater than 2 S / m, greater than 4 S / m, greater than 5 S / m, greater than 7 S / m, or greater than 10 S / m.

[0065] The upper limit of the conductivity of the counter electrode is not limited, but for example, it can be less than 100 S / m, less than 90 S / m, less than 85 S / m, or less than 80 S / m.

[0066] The conductivity represents the degree of current transmission between electrodes or electrodes, and can be represented by the reciprocal of resistivity.

[0067] Within the aforementioned range, relatively low energy can be used to more easily initiate electrochemical reactions between the electrode current collector and the electrode active material layer.

[0068] According to an exemplary embodiment, the counter electrode can be a reverse electrode. For example, current can be transferred to the working electrode (the electrode), thereby making it easier to initiate an electrochemical reaction on the working electrode.

[0069] Figures 2 to 4 This is a schematic diagram illustrating an electrode separation system according to an exemplary embodiment.

[0070] Reference Figures 1 to 4 Electrode 100 and counter electrode 130 can be partially immersed in conductive solution 120 (e.g., S20 process).

[0071] By partially immersing the electrode 100 and counter electrode 130 in the conductive solution 120, the electrode current collector and the electrode active material layer can be effectively separated under the control of the following electrical signal, and a high recovery rate of the electrode active material can be achieved.

[0072] For example, when either or more of electrode 100 and counter electrode 130 are completely immersed in conductive solution 120, the electrochemical reaction becomes uncontrolled, causing metal from the electrode current collector to deposit into conductive solution 120. This may result in a large amount of impurities on the electrode active material layer, or metal from the electrode active material layer depositing into conductive solution 120, potentially further reducing the recovery rate of the electrode active material. Furthermore, the energy consumption for the electrochemical reaction may increase, potentially further reducing electrode separation efficiency.

[0073] According to an exemplary embodiment, less than 99.9% of the total area of ​​electrode 100 may be immersed in conductive solution 120.

[0074] For example, electrode 100 can be electrically connected to the electrical signal application part 250 described below, and the remaining area, except for the part used to prevent short circuits, can be immersed in conductive solution 120.

[0075] In some embodiments, 10% to 99.9%, 15% to 99%, 20% to 97%, or 25% to 95% of the total area of ​​electrode 100 may be immersed in conductive solution 120. Within these ranges, the current required for separation can be reduced, and the separation time can be shortened, thus further improving electrode separation efficiency.

[0076] According to an exemplary embodiment, the conductive solution 120 may contain a substance that can form an electric current flow between the electrode 100 and the counter electrode 130.

[0077] According to an exemplary embodiment, the conductive solution 120 may contain a solvent and an electrolyte.

[0078] Examples of solvents include, for instance, water-based solvents including water; and organic solvents including propylene carbonate (PC), ethylene carbonate (EC), butene carbonate, diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, etc. These can be used alone or in combination of two or more.

[0079] Examples of electrolytes include metal salts containing lithium, nickel, manganese, cobalt, aluminum, iron, etc., as cations. Examples of metal salts include nitrates, sulfates, carbonates, phosphates, acetates, halides, etc.

[0080] According to an exemplary embodiment, the conductive solution 120 may contain an aqueous solvent.

[0081] The water-based solvent can refer to a solvent that contains water (H2O) as its main component, such as distilled water or ultrapure water. For example, the water-based solvent can refer to a solvent in which the total weight of water accounts for more than 90%, and the water-based solvent may also partially contain methanol, ethanol, isopropanol, acetone, tetrahydrofuran, dimethyl sulfoxide, etc.

[0082] In one embodiment, the conductive solution 120 may contain water.

[0083] With the application of the following electrical signal, the water-based solvent can generate gas, thus making it easier to separate the electrode current collector and the electrode active material layer.

[0084] According to an exemplary embodiment, the conductive solution 120 may contain a transition metal.

[0085] For example, the conductive solution 120 may contain a transition metal salt. The transition metal may include, for example, metals such as nickel, manganese, and cobalt, which are included as the above-mentioned positive electrode active material.

[0086] The conductive solution 120 containing transition metals can promote the catalytic effect of the electrode active material, thus further accelerating the separation of the electrode current collector and the electrode active material layer.

[0087] According to an exemplary embodiment, the transition metal may include one or more of nickel, cobalt, and manganese.

[0088] In some implementations, the transition metal may include nickel, cobalt, and manganese.

[0089] Nickel, cobalt, and manganese can act as catalysts together with electrode active materials and can be removed along with the electrode active materials, thus eliminating the need for impurity removal processes.

[0090] In some embodiments, the number of nickel moles in the total number of transition metals can be 0.2 to 0.9, 0.25 to 0.85, 0.28 to 0.80, or 0.3 to 0.75.

[0091] Within the aforementioned range, oxygen generation reactions can be promoted, thus further facilitating the physical separation of the electrode current collector and the electrode active material layer.

[0092] In some embodiments, the molar number of cobalt in the total number of moles of the transition metal can be 0.05 to 0.45, 0.10 to 0.43, 0.15 to 0.42, or 0.20 to 0.4.

[0093] In some embodiments, the molar number of manganese in the total number of transition metals can be 0.05 to 0.45, 0.10 to 0.43, 0.15 to 0.42, or 0.20 to 0.4.

[0094] In some embodiments, the concentration of the transition metal in the conductive solution 120 can be 0.2M to 1.5M, 0.3M to 1.3M, 0.4M to 1.1M, or 0.5M to 1.0M.

[0095] Within the aforementioned range, metal deposition in the electrode current collector caused by transition metals can be suppressed. Furthermore, the pH increase of the conductive solution 120 can be suppressed, thereby further suppressing the increase in oxygen generation potential and thus further suppressing the decrease in transition metal recovery rate.

[0096] For example, when the concentration of the transition metal exceeds the aforementioned range, the solubility of the metal (e.g., aluminum) desorbed from the electrode current collector in the conductive solution 120 may further increase. Therefore, the content of impurities contained in the separated electrode active material may further increase.

[0097] In some embodiments, the conductive solution 120 may also contain one or more of aluminum and iron. For example, when the positive electrode active material contains aluminum or iron, the conductive solution 120 may contain metal salts containing aluminum or iron.

[0098] According to an exemplary embodiment, the temperature of the conductive solution 120 can be maintained between 0°C and 80°C. For example, the above temperature can be maintained even under the condition of applying an electrical signal as described below.

[0099] Within the aforementioned temperature range, the movement of solvent molecules in the conductive solution can be promoted, thereby promoting the generation of gas caused by the application of the electrical signal, which in turn can further promote electrode separation.

[0100] According to an exemplary embodiment, electrode 100 and counter electrode 130 can be separated by separation section 140.

[0101] For example, the separating part 140 can be provided on the counter electrode 130, the moving part 270 can be provided on the separating part 140, and the electrode 100 can be provided on the moving part 270 (see reference). Figure 2 ).

[0102] For example, the separation section 140 can be provided on the counter electrode 130, and the electrode 100 can be provided on the separation section 140 (see reference). Figure 3 ).

[0103] Electrode 100 and counter electrode 130 can be physically separated by separation section 140.

[0104] For example, a separation portion 140 can be formed on a portion of the counter electrode 130, thereby blocking the physical contact between the counter electrode 130 and the electrode 100 and preventing short circuits. For example, the separation portion 140 can be formed on a portion of the counter electrode 130, allowing that portion to be exposed to the conductive solution 120, thus enabling current flow. Considering the physical separation via the separation portion 140, the movement via the moving portion 270, and the increase in reaction area, the electrode 100 and the counter electrode 130 can exist in various forms.

[0105] According to an exemplary embodiment, a substance permeable to ions can be used as the separation section 140.

[0106] For example, polypropylene, polyethylene, polycarbonate, polyimide, polyurethane, polyvinylidene fluoride, polyvinylidene-hexafluoropropylene copolymer, polyethylene oxide, ion exchange membrane, glass fiber, and ceramic diaphragm can be used as materials for the separation section.

[0107] In some embodiments, electrode 100 and counter electrode 130 may also be partially immersed in a conductive solution without separation section 140 (see reference). Figure 4 In this case, electrode 100 and counter electrode 130 can be physically separated.

[0108] According to an exemplary embodiment, the electrode 100 can be moved by the moving part 270. For example, the electrode 100 can be moved during the application of an electrical signal as described below.

[0109] The method of moving electrode 100 is not limited. For example, electrode 100 can be placed on a circular roller and the circular roller can be rotated at a constant speed so that electrode 100 moves in the direction of increasing area immersed in conductive solution 120.

[0110] Since the electrode 100 can be moved by the moving part 270, the electrode 100 can be immersed in the conductive solution 120 with a relatively small area in the early stage of the reaction, thereby further improving the efficiency of the electrochemical reaction.

[0111] According to an exemplary embodiment, an electrical signal can be applied via the electrical signal application unit 250 (e.g., process S30).

[0112] According to an exemplary embodiment, electrode 100 and counter electrode 130 can be connected to electrical signal application unit 250. The current flowing through electrode 100, counter electrode 130 and conductive solution 120 can be controlled by electrical signal application unit 250.

[0113] For example, an electrical signal can be applied through an electrical signal application unit 250 that includes a power supply device, a current generator, a pulse generator, etc.

[0114] By controlling the current through the electrical signal application unit 250, the electrode separation efficiency can be further improved, for example, by shortening the electrode separation time, reducing energy consumption, and reducing impurities.

[0115] According to an exemplary embodiment, gas can be generated between the electrode current collector and the electrode active material layer by applying an electrical signal.

[0116] By generating gas, the electrode current collector can be separated from the electrode active material layer. For example, by generating gas, a space can be formed and expanded between the electrode current collector and the electrode active material layer, thus enabling the separation of the electrode current collector from the electrode active material layer.

[0117] For example, the conductive solution 120 may contain a water-based solvent, and the water in the water-based solvent may be electrochemically decomposed to produce oxygen. For example, water may be decomposed according to the following reaction formula 1.

[0118] [Reaction Formula 1]

[0119] 2H₂O → O₂ (gas) + 4H₂O + +4e -

[0120] The transition metal contained in the electrode active material layer or the transition metal contained in the conductive solution 120 can act as a catalyst to further promote the oxygen generation reaction.

[0121] In some embodiments, the gas may contain oxygen. Promoting the oxygen generation reaction can further facilitate the separation of the electrode current collector from the electrode active material layer.

[0122] According to an exemplary embodiment, the electrical signal may include a DC signal.

[0123] By applying a DC signal, the current can be stably maintained within a predetermined range, thereby promoting gas generation with relatively low energy. Furthermore, the electrode can be separated while suppressing the deposition of metals contained in the electrode current collector and the electrode active material layer.

[0124] For example, when a pulse signal with large voltage fluctuations is applied, the metal in the electrode current collector may desorb and dissolve in the conductive solution 120, which may further reduce the recovery rate of the electrode active material.

[0125] According to an exemplary implementation, the electrical signal can be applied to make the current value from 0.01A to 8A.

[0126] In some implementations, the electrical signal may be applied to produce a current value of 0.01A to 7A, 0.05A to 6.5A, 0.07A to 6A, 0.09A to 5.5A, or 0.1A to 5A.

[0127] Within the aforementioned range, the desorption of metal from the electrode current collector or electrode active material layer can be suppressed, thereby reducing impurities and further improving the recovery efficiency of the electrode active material.

[0128] According to an exemplary embodiment, the electrode active material 300 can be precipitated in the conductive solution 120.

[0129] For example, as the electrode current collector separates from the electrode active material layer, the electrode active material 300 can be separated from the electrode active material layer, and the electrode active material 300 can act as a catalyst for gas generation and precipitate.

[0130] According to an exemplary implementation, electrode active material 300 can be recovered.

[0131] For example, electrode active material 300, which is insoluble in conductive solution 120, can be collected and washed with water to obtain electrode active material. By applying an electrical signal to separate the electrode active material, electrode active material with lower impurity content can be obtained with a higher recovery rate.

[0132] According to an exemplary embodiment, the recovery rate of the electrode active material 300 can be above 80%, above 85%, above 87%, above 88%, above 89%, or above 90%. There is no upper limit to the recovery rate of the electrode active material 300, but for example, it can be below 99.9% or below 99.5%.

[0133] The recovery rate can be calculated according to the following formula 1.

[0134] [Formula 1]

[0135] Recovery rate = 1 - (content of electrode active material remaining on the electrode current collector after separation of the electrode active material layer and the electrode current collector / content of electrode active material contained in the electrode before separation) 100

[0136] Although the time and energy required for electrode separation can be partially adjusted based on the size of electrode 100, the immersion area of ​​electrode 100, the current intensity, the volume of conductive solution, etc., the required time and energy can be reduced by applying an electrical signal, thereby effectively separating the electrodes.

[0137] In some embodiments, electrode 100 and counter electrode 130 may not be connected to the electrical signal application section 250. For example, electrode 100 and counter electrode 130 may be connected by wires and partially immersed in conductive solution 120 to generate an electric current.

[0138] An electrode separation system according to an exemplary embodiment includes: an electrode portion including an electrode current collector and an electrode active material layer; a counter electrode portion electrically connected to the electrode portion; a reaction portion 200 for partially immersing the electrode portion and the counter electrode portion in a conductive solution; and an electrical signal application portion for applying an electrical signal.

[0139] The electrode section and the counter electrode section can refer to the electrode and counter electrode of the above embodiment.

[0140] The reaction section 200 may include a reactor containing a conductive solution. For example, a conductive solution may be added to the reactor, and the electrode section and the counter electrode section may be partially immersed in the conductive solution.

[0141] The conductive solution and the electrical signal application part can be described with reference to the above-described embodiment.

[0142] The following are embodiments provided to aid in understanding the present invention. However, these embodiments are merely illustrative and are not intended to limit the scope of the claims. Various changes and modifications can be made to the embodiments within the scope of the present invention and its technical concept. This is obvious to those skilled in the art, and such variations and modifications are naturally within the scope of the claims.

[0143] Example 1

[0144] The waste positive electrode is heat-treated in an air atmosphere at 400°C to obtain waste positive electrode material, which includes a positive electrode active material layer containing nickel, cobalt and manganese and a positive electrode current collector containing aluminum.

[0145] Nickel sulfate (NiSO4), cobalt sulfate (CoSO4), and manganese sulfate (MnSO4) are mixed to achieve a molar ratio of Ni, Co, and Mn of 1:1:1, and water is added to prepare 200 mL of a 1 M conductive solution. This conductive solution is then added to a reactor, and a nickel foil (serving as the counter electrode) is immersed in the solution. A layer of glass fiber covering the nickel foil is stacked, and a circular roller is mounted on the glass fiber. Waste positive electrode material is then placed on the circular roller.

[0146] The nickel foil, waste positive electrode material, and the electrical signal application unit are electrically connected, and then an electrical signal is applied to separate the positive electrode active material layer from the positive electrode current collector. The electrical signal is applied until the applied electrical signal can no longer be maintained at 0.1A. In addition, the precipitate of the conductive solution is washed with water to obtain the positive electrode active material.

[0147] Examples 2 to 11

[0148] Except for changing the conductive solution and electrical signal according to Table 1 below, the positive electrode active material layer and positive electrode current collector were separated from the waste positive electrode material and the positive electrode active material was obtained by the same method as in Example 1. In Table 1 below, the electrical pulses were applied as follows: 10V (20 seconds) / rest (10 seconds) / -10V (20 seconds).

[0149] [Table 1]

[0150]

[0151] Comparative example

[0152] Waste cathode material is prepared using the same method as in Example 1.

[0153] At 50°C, the waste positive electrode material is immersed in a 2M sodium hydroxide (NaOH) aqueous solution and stirred for 3 hours to separate the positive electrode current collector from the positive electrode active material layer. The positive electrode current collector and the positive electrode active material layer are then washed with water to obtain the positive electrode active material.

[0154] Experimental Example

[0155] (1) Analysis of separation time

[0156] The separation time between the positive current collector and the positive active material layer in the measurement embodiment is measured as the time during which the applied electrical signal can no longer be maintained at 0.1A after the positive current collector and the positive active material layer are physically separated.

[0157] In the separation of the positive electrode according to the comparative example, a gap is generated between the positive electrode current collector and the positive electrode active material layer after at least 1 hour.

[0158] (2) Analysis of aluminum leaching

[0159] In the separation of the positive electrode according to the embodiment, the aluminum content contained in the conductive solution was measured. Furthermore, in the separation of the positive electrode according to the comparative example, the aluminum content contained in the aqueous sodium hydroxide solution was measured. The aluminum content was measured by inductively coupled plasma-optical emission spectrometry (ICP-OES).

[0160] (3) Analysis of recovery rate

[0161] The recovery rate of the positive electrode active material in the examples and comparative examples was measured according to Formula 1 below. The content of the positive electrode active material was measured by ICP-OES.

[0162] [Formula 1]

[0163] Recovery rate = 1 - (content of positive electrode active material remaining on the positive electrode current collector after separation of the positive electrode active material layer and the positive electrode current collector / content of positive electrode active material contained in the positive electrode before separation) 100

[0164] (4) Analysis of energy efficiency

[0165] When the positive electrode is separated according to the embodiment, the energy consumed by the electrical signal application part is measured, and the energy consumption per unit area is calculated.

[0166] The analytical results of the separation time, aluminum leaching amount, recovery rate and energy efficiency are shown in Table 2 below.

[0167] [Table 2]

[0168]

[0169] Referring to Table 2, in accordance with the embodiments, electrodes can be separated with short separation time, low aluminum leaching, high positive electrode recovery rate, and low energy consumption.

[0170] In the comparative case, the electrode separation time was significantly longer and the aluminum content in the solution was higher.

[0171] In Example 3, which uses a conductive solution with a relatively high concentration of transition metals, the amount of aluminum leached increases and the recovery rate decreases relatively.

[0172] In Examples 4 and 5, which used sodium sulfate, the separation time and energy consumption increased relatively.

[0173] In Example 6, where an electrical pulse signal is applied, the separation time and energy consumption are relatively increased.

[0174] In Example 7, which used sodium sulfate and applied an electrical pulse signal, the amount of aluminum leaching increased and the recovery rate of the positive electrode active material decreased.

[0175] In Example 11, where an electrical signal is applied in a manner that allows a relatively high current flow, the amount of aluminum dissolved increases, and the recovery rate of the positive electrode active material decreases.

Claims

1. An electrode separation method, comprising the following steps: The electrode, which includes an electrode current collector and an electrode active material layer, and the counter electrode portion electrically connected to the electrode, are immersed in a conductive solution; as well as Apply an electrical signal.

2. The electrode separation method according to claim 1, wherein, The step of applying an electrical signal includes generating gas between the electrode current collector and the electrode active material layer.

3. The electrode separation method according to claim 1, wherein, The step of applying an electrical signal includes applying a DC signal.

4. The electrode separation method according to claim 1, wherein, The step of applying an electrical signal includes applying an electrical signal to make the current value from 0.01A to 8A.

5. The electrode separation method according to claim 1, wherein, The conductive solution contains a water-based solvent.

6. The electrode separation method according to claim 1, wherein, The conductive solution contains a transition metal.

7. The electrode separation method according to claim 6, wherein, The transition metal comprises one or more of nickel, cobalt, and manganese.

8. The electrode separation method according to claim 6, wherein, The transition metal includes nickel, and the number of moles of nickel in the total number of moles of the transition metal is between 0.2 and 0.

9.

9. The electrode separation method according to claim 6, wherein, The concentration of the transition metal in the conductive solution is from 0.2 M to 1.5 M.

10. The electrode separation method according to claim 1, wherein, The electrode is moved by the moving part.

11. The electrode separation method according to claim 10, wherein, The electrode and the counter electrode are separated by a separation section.

12. The electrode separation method according to claim 1, wherein, The electrode is obtained by heat-treating waste lithium secondary batteries at temperatures below 500°C.

13. The electrode separation method according to claim 1, wherein, The conductivity of the counter electrode is greater than 1 S / m.

14. An electrode separation system, comprising: The electrode portion includes an electrode current collector and an electrode active material layer; The counter electrode section is electrically connected to the electrode section; A reaction section is used to immerse the electrode section and the counter electrode section in a conductive solution. as well as An electrical signal applying unit is used to apply an electrical signal.

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