KR20230067057A - A method of recovering and restoring a cathode active material from a waste battery - Google Patents

Abstract

The present invention can provide a method for collecting and simultaneously restoring positive electrode active materials from waste batteries through a simple process. According to the present invention, the collected and restored positive electrode active materials may have physical properties equivalent to those of the positive electrode active materials before use. Therefore, the collected and restored positive electrode active materials can be directly inputted to battery manufacturing without any additional processing, thereby saving time and costs.

Description

A method of recovering and restoring a cathode active material from a waste battery at the same time {A method of recovering and restoring a cathode active material from a waste battery}

The present invention relates to a method for recovering and simultaneously restoring a positive electrode active material from a waste battery.

Due to the recent rapid growth of the electric vehicle market, the global waste battery treatment market is expected to grow to about 20 trillion won by 2030, and about 80,000 waste batteries are expected to be generated in Korea by 2029.

Currently, recycling of waste batteries is mainly focused on the process of recovering valuable metals. However, the existing urban mining technology has a problem of high carbon emission, very low profitability, high process cost, and low economic feasibility (about $6.7/kWh loss) due to low sales revenue of recovered metal. In addition, as secondary battery manufacturers are reducing the content of expensive metals such as cobalt, the economic deterioration of urban mining technology is expected to accelerate.

Meanwhile, research is being conducted on the recovery of cathode materials from waste batteries. For example, Prior Document 1 discloses a method of recovering a positive electrode active material from an aluminum current collector. However, since the positive electrode active material recovered by Prior Document 1 is in a state of deterioration due to various causes for hundreds to thousands of cycles, there is a problem that it cannot be used immediately without additional treatment.

Therefore, it is necessary to develop innovative recycling technologies that improve the problems of the existing waste battery recycling process in order to lead the global market and become self-sufficient in battery materials that are entirely dependent on imports.

{Prior Document 1} KR2021-0036206

One object of the present invention is to solve the problems of economic feasibility and environmental pollution of the existing valuable metal recovery process.

Another object of the present invention is to recover and simultaneously restore a positive electrode active material having physical properties equivalent to those of a positive electrode active material before use from a waste battery through a simple process.

The technical problem to be achieved by the present invention is not limited to the above-mentioned technical problem, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

For example, the present application may relate to a method for recovering and restoring a cathode active material, in which a cathode desorption step and a lithium insertion step are simultaneously performed.

The cathode desorption step and lithium insertion step may be performed, for example, in a solution containing a lithium precursor.

The lithium precursor is composed of, for example, lithium acetate, lithium hydroxide, lithium nitrate, lithium sulphate, lithium perchlorate, and lithium chloride (LiCl). It may be one or more selected from the group.

For example, the lithium precursor may be included in the range of 0.01 mol/L to 10 mol/L in the solution.

The solution containing the lithium precursor is, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, hexylene glycol and 1,2-hexane glycol solvents including decanediol (1,2-hexadecanediol); or methyl glycol, butyl glycol, butyl triglycol, butyl polyglycol, hexyl glycol, hexyldiglycol, ethylhexylglycol, ethylhexyldiglycol, arylglycol, phenylglycol, phenyldiglycol, benzyl glycol, methylpropylene glycol, methylpropylene One or two selected from the group consisting of glycol ether solvents including diglycol, methyl propylene triglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol, butyl propylene diglycol, phenyl propylene glycol and methyl propylene glycol acetate It may be formed by dissolving the lithium precursor in a solvent that is a mixture of more than one species.

The cathode desorption step and lithium insertion step may include, for example, heat treatment.

The heat treatment may be performed within a temperature range of, for example, 100 °C to 300 °C.

The heat treatment may be performed within a time range of 1 minute to 120 minutes, for example.

The present application may relate to a method for recovering and restoring a positive electrode active material, including, for example, additional heat treatment and adding lithium.

The additional heat treatment and adding lithium may be performed at a temperature in the range of, for example, 400 °C to 1200 °C.

The positive electrode active material recovery and restoration method of the present application may further include, for example, recovering positive electrode scrap from waste batteries.

The method for recovering and restoring the positive electrode active material of the present application may further include, for example, centrifugation.

The method for recovering and restoring the positive electrode active material of the present application may further include, for example, a drying step.

The present invention can provide a method for recovering and simultaneously restoring a cathode active material from a waste battery through a simple process. The positive active material recovered and restored according to the present invention may have physical properties equivalent to those of the positive active material before use. Therefore, the recovered and restored cathode active material can be directly used in battery manufacturing without any additional treatment, thereby reducing time and cost.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the description of the present invention or the configuration of the invention described in the claims.

1 to 3 are graphs showing the results of XRD analysis on samples of Examples and Comparative Examples.
4 is FE-SEM images of samples of Comparative Example (a) and Example 1 (b) in turn.
5 is a graph showing the capacity evaluation results of Example 13, Comparative Example 2, and Reference Example 2.

Among the physical properties mentioned in this specification, the physical properties in which the measurement temperature and/or the measurement pressure affect the results are the results measured at room temperature and/or normal pressure, unless otherwise specified.

The term room temperature is a natural temperature that is not warmed or cooled, and means, for example, any temperature in the range of 10 ° C to 30 ° C, about 23 ° C or about 25 ° C. In addition, the unit of temperature in this specification is °C unless otherwise specified.

The term normal pressure is a natural pressure that is not pressurized or reduced, and usually means about 1 atmosphere of atmospheric pressure level.

In the present specification, in the case of physical properties in which measured humidity affects the result, unless otherwise specified, the corresponding physical property is a physical property measured at natural humidity that is not particularly controlled at room temperature and / or normal pressure.

This application may relate, for example, to a method for recovering and restoring a positive electrode active material. The method of recovering and restoring the cathode active material may mean, for example, a method of simultaneously recovering and restoring the cathode active material from a waste battery. In the present specification, the waste battery may mean, for example, a secondary battery exhibiting a maximum capacity reduced by 20% or more compared to the initial maximum capacity. In another example, the waste battery may refer to a secondary battery operated over hundreds to thousands of cycles (charge and discharge). In another example, the waste battery may refer to a secondary battery that is difficult to use anymore because it does not satisfy the required performance due to various reasons including deterioration. The waste battery may be a concept including, for example, electrode scrap generated in the secondary battery manufacturing process or electricity generated in a defect in the secondary battery manufacturing process. The waste battery may include, for example, a waste anode or a waste cathode.

Recently, with the rapid growth of the electric vehicle market, interest in treatment and recycling of waste batteries is also increasing. As a method for treating and recycling such waste batteries, research on methods for recovering valuable metals such as cobalt from waste batteries has been actively conducted. However, this method has a problem of low economic feasibility and environmental pollution due to the generation of a large amount of carbon. Accordingly, research on a method for recovering a cathode active material from a waste battery was also conducted. However, in the case of the conventional method for recovering the positive electrode active material, the positive electrode active material deteriorated after being used for hundreds to thousands of cycles and is difficult to exhibit its performance is recovered, and it is difficult to directly reuse it in a battery or the like without additional treatment. . Accordingly, the present inventors have devised a method for recovering and restoring a positive electrode active material that solves the above problems and enables the provision of a positive electrode active material that can be directly used in battery manufacturing through a simple process without additional treatment.

The method for recovering and restoring the positive electrode active material of the present application may, for example, simultaneously perform a desorption step and a lithium insertion step. In the present specification, the cathode desorption step may mean, for example, a step of separating the cathode mixture layer and the current collector of cathode scrap. In this specification, the term positive electrode scrap may refer to a positive electrode recovered from a waste battery. For example, the positive electrode may have a structure in which a positive electrode mixture layer is laminated on one side of a current collector.

The current collector may be, for example, an aluminum (Al) current collector, but is not limited thereto, and is not limited as long as it can be used as an anode current collector.

The cathode mixture layer may include, for example, a cathode active material, a binder, and/or a conductive material. The cathode active material may be a general cathode active material used in the art, and may be, for example, lithium transition metal oxide. The lithium transition metal oxide may include, for example, at least one transition metal selected from among nickel, cobalt, and manganese. The cathode active material may be, for example, lithium cobalt oxide (LiCoO ₂ ); lithium nickel oxide (LiNiO ₂ ); Li[Ni _a Co _b Mn _c M ¹ _d ]O ₂ (wherein M ¹ is any one or two or more elements selected from the group consisting of Al, Ga, and In, and 0.3≤a≤1.0, 0 ≤b≤0.5, 0≤c≤0.5, 0≤d≤0.1 and a+b+c+d = 1); Li(Li _e M ² _fe-f' M ³ _f' )O _2-g A _g (wherein 0≤e≤0.2, 0.6≤f≤1, 0≤f'≤0.2, 0≤g≤0.2, and , M ² includes at least one selected from the group consisting of Mn, Ni, Co, Fe, Cr, V, Cu, Zn and Ti, and M ³ is one selected from the group consisting of Al, Mg and B above, and A is at least one selected from the group consisting of P, F, S and N), layered compounds, or compounds substituted with one or more transition metals; lithium manganese oxides such as Li _1+h Mn _2-h O ₄ (0≤h≤0.33 in the above formula), LiMnO ₃ , LiMn ₂ O ₃ , and LiMnO ₂ ; Formula LiNi _1-i M ⁴ _i O ₂ (wherein M ⁴ is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and 0.01≤i≤0.3) Ni site type lithium nickel oxide expressed; Formula LiMn _2-j M ⁵ _j O ₂ (wherein M ⁵ is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and 0.01≤j≤0.1) or Li ₂ Mn ₃ a lithium manganese composite oxide represented by M ⁶ O ₈ (wherein M ⁶ is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); It may be LiMn ₂ O ₄ in which Li part of the formula is substituted with an alkaline earth metal ion. Preferably, the cathode active material may be lithium nickel cobalt manganese oxide containing nickel, cobalt, and manganese as transition metals.

The binder serves to improve adhesion between particles of an electrode (anode or cathode) active material and/or adhesion between an electrode active material and a current collector, and general electrode binders used in the art may be used. Specific examples of the binder include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose ( CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber (SBR) , fluororubber, or various copolymers thereof, and the like, and one type alone or a mixture of two or more types thereof may be used.

The conductive material is used to impart conductivity to the electrode (anode or cathode), and any material having electronic conductivity without causing chemical change in the battery may be used without particular limitation. The conductive material may be, for example, graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Or it may be a conductive polymer such as a polyphenylene derivative, etc., and one of these may be used alone or in a mixture of two or more.

In the present application, the detaching of the positive electrode may mean that the current collector is separated from the positive electrode composite material layer while maintaining a plate shape, or that the current collector is powdered and separated from the positive electrode composite material layer. Powdering of the current collector may mean, for example, that the current collector is melted and oxidized by heat treatment over a predetermined range. The positive electrode mixture layer separated from the current collector may show a shape in which the plate shape is broken while maintaining the plate shape in a solution described below, for example.

In the present specification, the lithium insertion step may mean, for example, a step of inserting lithium into the positive electrode active material included in the positive electrode mixture layer. A cathode active material included in the cathode scrap obtained from a waste battery may be in a deteriorated state. In the present specification, deterioration of the positive electrode active material may mean, for example, a state in which lithium is insufficient due to desorption of lithium ions included in the positive electrode active material. The deterioration may mean that, for example, structural instability of the positive electrode active material occurs while another component, for example, a transition metal included in the positive electrode active material, fills a large amount of lithium vacancies generated during the charging process. The deterioration of the cathode active material is also caused by various causes, such as, for example, the instability of the crystal structure of the cathode active material, the resulting desorption of oxygen in the crystal structure, decomposition of the electrolyte solution at high voltage, and/or the elution of transition metals from the electrolyte solution. may occur.

Since the active material in a degraded state as described above causes a serious decrease in the capacity of the electrode, in the prior art, even if the cathode active material is recovered from waste batteries and/or cathode scrap, there is a problem that it cannot be immediately put into the battery. However, the positive electrode active material recovery method of the present application can recover a positive electrode active material having physical properties equivalent to those of the positive electrode active material (pristine) from a waste battery through a simple process by simultaneously performing the positive electrode desorption step and the lithium insertion step as described above. can Accordingly, the recovered cathode active material can be directly used in battery manufacturing without any additional treatment, thereby reducing time and cost.

The cathode desorption step and lithium insertion step may be performed, for example, in a solution containing a lithium precursor. The fact that the cathode desorption step and the lithium insertion step are performed in a solution containing a lithium precursor means that the cathode desorption step and lithium insertion step are performed in a state in which the cathode scrap is put into a solution containing the lithium precursor. can do.

The lithium precursor is composed of, for example, lithium acetate, lithium nitrate, lithium sulphate, lithium perchlorate, lithium hydroxide, and lithium chloride (LiCl). It may be one or more selected from the group. The lithium precursor may be preferably lithium acetate in terms of miscibility with the solvent.

For example, the lithium precursor may be included in the range of 0.01 mol/L to 10 mol/L in the solution. In another example, the lithium precursor is 0.02 mol / L or more, 0.03 mol / L or more, 0.04 mol / L or more, 0.05 mol / L or more, 0.06 mol / L or more, 0.07 mol / L or more, 0.08 mol / L or more in the solution or 0.09 mol/L or more, 9 mol/L or less, 8 mol/L or less, 7 mol/L or less, 6 mol/L or less, 5 mol/L or less, 4 mol/L or less, 3 mol/L less than 2 mol/L, less than 1 mol/L, less than 0.9 mol/L, less than 0.8 mol/L, less than 0.7 mol/L, less than 0.6 mol/L, less than 0.5 mol/L or less than 0.4 mol/L can In the present specification, that the lithium precursor is included in a specific mol/L solution may mean that the lithium precursor is included in a specific mol number with respect to 1L of a solvent described later.

In this application, the solution containing the lithium precursor is, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, hexylene glycol and 1 , glycol solvents including 2-hexadecanediol (1,2-hexadecanediol); or methyl glycol, butyl glycol, butyl triglycol, butyl polyglycol, hexyl glycol, hexyldiglycol, ethylhexylglycol, ethylhexyldiglycol, arylglycol, phenylglycol, phenyldiglycol, benzyl glycol, methylpropylene glycol, methylpropylene One or two selected from the group consisting of glycol ether solvents including diglycol, methyl propylene triglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol, butyl propylene diglycol, phenyl propylene glycol and methyl propylene glycol acetate It may be formed by dissolving the lithium precursor in a solvent that is a mixture of more than one species. The type of the solvent is not particularly limited, but may be preferably a diethylene glycol solvent in terms of reaction temperature and reaction time.

In the present application, the cathode desorption step and lithium insertion step may include, for example, heat treatment. In the present specification, that the cathode desorption step and the lithium insertion step include heat treatment may mean that the cathode desorption and lithium insertion steps are performed through a heat treatment process.

The heat treatment may be performed within a temperature range of, for example, 100 °C to 300 °C. In another example, the heat treatment step is performed at a temperature of 110 ° C or more, 120 ° C or more, 130 ° C or more or 140 ° C or more, or 290 ° C or less, 280 ° C or less, 270 ° C or less, 260 ° C or less, 250 ° C or less, 240 ° C or less °C or less, 230 °C or less, 220 °C or less, 210 °C or less, 200 °C or less, 190 °C or less or 180 °C or less. As the heat treatment is performed within the above temperature range, it may be possible to recover and restore the cathode active material in which lithium is sufficiently inserted.

The heat treatment may be performed within a time range of 1 minute to 120 minutes, for example. In another example, the heat treatment step is performed for 2 minutes or more, 3 minutes or more, 4 minutes or more, 5 minutes or more, 6 minutes or more, 7 minutes or more, 8 minutes or more or 9 minutes or more, 110 minutes or less, 100 minutes or less, 90 minutes or less, 80 minutes or less, or 70 minutes or less. As the heat treatment is performed within the above time range, it may be possible to recover the cathode active material in which lithium is sufficiently inserted.

The method for recovering and restoring the positive electrode active material of the present application may include, for example, additional heat treatment and lithium addition steps. The additional heat treatment and adding lithium may be performed at a temperature in the range of, for example, 400 °C to 1200 °C. In another example, the temperature is 450 ° C or more, 500 ° C or more, 550 ° C or more, 600 ° C or more, 650 ° C or more, 700 ° C or more, 750 ° C or more, 800 ° C or more or 850 ° C or more, 1150 ° C or less, 1100 ° C It may be 1050 ° C or less, 1000 ° C or less, or 950 ° C or less. The additional heat treatment and adding lithium may be performed for a time within the range of, for example, 6 hours to 15 hours. In another example, the additional heat treatment and lithium addition step may be performed for 7 hours or more, 8 hours or more, or 9 hours or more, or 14 hours or less, 13 hours or less, 12 hours or less, or 11 hours or less.

The additional heat treatment and adding lithium may be performed, for example, in a state in which a lithium compound is introduced. The lithium compound is selected from the group consisting of lithium acetate, lithium nitrate, lithium sulphate, lithium perchlorate, lithium hydroxide and lithium chloride (LiCl) One or more may be used. For example, the lithium compound may be introduced in the range of 0.1 part by weight to 20 parts by weight based on 100 parts by weight of the positive electrode active material. In another example, the lithium compound is present in an amount of 0.5 parts by weight or more, 1 part by weight or more, 1.5 parts by weight or more, 2 parts by weight or more, 2.5 parts by weight or more, 3 parts by weight or more, 3.5 parts by weight or more, based on 100 parts by weight of the positive electrode active material. 4 parts by weight or more or 4.5 parts by weight or more introduced, 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 14 parts by weight or less, 13 parts by weight or less, 12 parts by weight or less 11 parts by weight or less, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less or 6 parts by weight or less may be introduced.

The method for recovering and restoring the cathode active material of the present application may restore a small amount of structural change through the additional heat treatment and lithium addition process as described above. In one example, the layered structure of the deteriorated cathode active material may change from the particle surface to a spinel structure and/or a rock salt structure. By performing an additional heat treatment and lithium addition process on the deteriorated cathode active material, the small amount of structural change as described above can also be restored, and through this, the cathode active material having performance equal to or higher than that of the pristine cathode active material of the same grade can be obtained. Recovery may be possible.

The positive electrode active material recovery and restoration method of the present application may further include, for example, recovering positive electrode scrap from waste batteries. Recovering cathode scrap from the waste battery may include, for example, when the waste battery is a battery containing an electrolyte, removing the electrolyte solution from the waste battery and inactivating the battery. The step of removing the electrolyte and inactivating the battery may be performed, for example, after punching or cutting the waste battery.

The method for recovering and restoring the positive electrode active material of the present application may further include, for example, centrifugation. The step of centrifuging may be performed, for example, after the step of detaching the positive electrode and the step of inserting lithium. The centrifugation may be performed, for example, on the positive electrode mixture part desorbed through the above-described positive electrode desorption step and lithium insertion step. In this specification, the term positive electrode mixture part may mean that the positive electrode mixture layer exists in a state in which the positive electrode mixture layer is separated from the current collector.

The centrifugation may be performed at a rotational speed in the range of, for example, 500 rpm to 10000 rpm. In another example, the rotation speed is 600 rpm or more, 700 rpm or more, 800 rpm or more, 900 rpm or more, 1000 rpm or more, 1100 rpm or more, 1200 rpm or more, 1300 rpm or more, 1400 rpm or more, 1500 rpm or more, 1600 rpm 1700 rpm or more, 1800 rpm or more, 1900 rpm or more, 2000 rpm or more, 2100 rpm or more, 2200 rpm or more, 2300 rpm or more, or 2400 rpm or more, or 9000 rpm or less, 8000 rpm or less, 7000 rpm or less, 6000 rpm or less , 5000 rpm or less, 4000 rpm or less, 3000 rpm or less, 2900 rpm or less, 2800 rpm or less, 2700 rpm or less, or 2600 rpm or less.

The centrifugation may be performed for a time within the range of, for example, 1 minute to 15 minutes. In another example, the centrifugation is performed for 2 minutes or more, 3 minutes or more, or 4 minutes or more, or 14 minutes or less, 13 minutes or less, 12 minutes or less, 11 minutes or less, 10 minutes or less, 9 minutes or less, 8 minutes or less. Hereinafter, it may be performed for a time of 7 minutes or less or 6 minutes or less, but is not limited thereto.

The method for recovering and restoring the positive electrode active material of the present application may further include, for example, a drying step. The drying step may be performed, for example, after the cathode desorption step and lithium insertion step and/or after the centrifugation step. The drying step may be performed, for example, on the recovered positive electrode mixture part and/or positive electrode active material.

The drying step may be performed at a temperature within the range of, for example, 30 °C to 250 °C. In another example, the drying temperature is 40 ° C or higher, 50 ° C or higher, 60 ° C or higher, 70 ° C or higher, 80 ° C or higher or 90 ° C or higher, or 240 ° C or lower, 230 ° C or lower, 220 ° C or lower, 210 ° C or lower, 200 ° C or less, 190 ° C or less, 180 ° C or less, 170 ° C or less, 160 ° C or less, 150 ° C or less, 140 ° C or less, 130 ° C or less, 120 ° C or less or 110 ° C or less, but is not limited thereto.

By having the above characteristics, the present application can provide a method for recovering and restoring a positive electrode active material having physical properties equivalent to those of the positive electrode active material before use through a simple process.

In one example, the positive electrode active material recovered and restored by the method of the present application may have a lithium amount of 0.95% by weight or more when elemental analysis is performed using an ICP-OES equipment. The ICP-OES elemental analysis may be performed in a manner according to the following examples. In another example, the amount of lithium in the recovered cathode active material may be 0.96 wt% or more, 0.97 wt% or more, 0.98 wt% or more, 0.99 wt% or more, or 1 wt% or more.

Hereinafter, embodiments of the present invention will be described in detail.

manufacturing example. Recovery of anode scrap from waste batteries

A lithium secondary battery cell with a capacity of 16Ah composed of an NCM-based positive electrode and a graphite negative electrode was charged and discharged for more than 1000 cycles, and the charge/discharge cell (waste battery) was disassembled to recover positive electrode scrap. Anode scrap is a layer in which a cathode active material layer containing an NCM-based cathode material, a binder, and carbon is laminated on the surface of an aluminum current collector.

Example 1.

After adding 0.025 mol of lithium acetate (C ₂ H ₃ LiO _2, JUNSEI) to 250 ml of a glycol (Diethylene glycol) solvent (C ₄ H ₁₀ O ₃ , Sigma aldrich), stir at room temperature for 12 hours to completely dissolve The solution was prepared. Subsequently, 2.5 g of the cathode scrap of Preparation Example was added to the solution, and maintained at a temperature of 150° C. for 10 minutes. Thereafter, the solution into which the cathode scraps were added was cooled to a temperature of 25° C., and washed three times with ethanol to collect the detached anode. After dispersing the positive electrode in NMP (N-Methyl-2-pyrrolidone, Sigma aldrich), 2 g of the positive electrode active material was extracted using a centrifuge. At this time, the centrifugation was performed for 5 minutes under the condition of 2500 rpm. After drying the positive electrode material obtained through centrifugation in an oven at 100 ° C., the final positive electrode active material was recovered.

Examples 2 to 11, Comparative Example 1 and Reference Example 1.

The final cathode active material was recovered in the same manner as in Example 1, except that the number of moles of lithium acetate, temperature, and time were changed as shown in Table 1 below.

[Table 1]

(Comparative Example 1 is a deteriorated positive electrode active material recovered without proceeding with the recovery and restoration method of the present invention, and Reference Example 1 is an unused positive electrode active material of the same grade)

Evaluation Example 1. XRD (X-ray diffraction)

For the extracted positive electrode active material sample, XRD analysis was performed by using XRD equipment (X'Pert PRO Multi Purpose, PANalytical Co.). At this time, the XRD was used by setting the conditions of Cu K α (λ = 1.5418 Å40 kV and 40 mA. In order to confirm the structural characteristics of the cathode active material obtained under the corresponding conditions, it was observed through X-ray diffraction analysis results, and the result graph is shown in Figures 1 to 3.

1 to 3, it can be seen that the peak positions of the structures of all the samples are almost similar when the structures of the comparative samples and the samples of the examples are analyzed. However, in the sample obtained through the comparative example, it can be confirmed that the peak at 18.5 degrees, which is the (003) plane, has moved to a low 2theta, and in the sample obtained through the example, it can be confirmed that the (003) plane has moved to a higher 2theta, similar to the Prisitne sample. can This is a phenomenon accompanied by a decrease in the distance between (003) planes as lithium ions are inserted between the planes during the process.

Evaluation Example 2. ICP-OES

As a result of elemental analysis using ICP-OES (PerkinElmer OPTIMA 4300 DV model) equipment for the extracted cathode active material sample, the amount of lithium in the cathode active material of the comparative example was 0.909, whereas the cathode active material obtained through Examples 2 to 4 was lithium. It was confirmed that this amount was 1 or more (1.011, 1.044 and 1.004 in that order). Through this, it can be inferred that the cathode active material of the embodiment is in a state in which lithium loss is supplemented.

Evaluation Example 3. FE-SEM

The particle shape of the extracted positive electrode active material samples was observed using FE-SEM equipment. As a result, as shown in FIG. 4 , it was confirmed that the surface of the deteriorated cathode active material particle ( FIG. 4a ) and the surface of the cathode active material of Example 1 ( FIG. 4b ) were similar.

Example 12

In order to restore the structural variation of the positive electrode active material of Example 3, 5% by weight of lithium hydroxide (sigma Aldrich) was introduced with respect to 100 parts by weight of the positive electrode active material, mixed in a solid state, and then additional heat treatment was performed at a temperature of 900 ° C. for 10 hours did

At this time, the structural change of the positive electrode active material means that the layered structure is transformed from the surface of the particle to a spinel structure and a rock salt structure as the positive electrode active material is cycled for a long time (since these structural changes are small, not found by XRD analysis).

Example 13

A positive electrode slurry was prepared by mixing the positive active material of Example 12, the conductive material (Super-P), and the binder (PVDF) in a weight ratio of 9:0.5:0.5 (positive active material: conductive material: binder).

Subsequently, the completed positive electrode slurry was applied on aluminum foil (thickness: 20 μm) by a doctor blade method (thickness: 120 μm), and then vacuum dried at a temperature of 120° C. to prepare a positive electrode.

Thereafter, a separator and a reference electrode were sequentially stacked on the cathode slurry layer, and then an electrolyte was injected to manufacture a half coin cell. At this time, Wscope's SC1622 was used as the separator, lithium metal was used as the reference electrode, and EC (Ethylene Carbonate) / EMC (Ethyl Methyl Carbonate) / DEC (Diethyl Carbonate) electrolyte containing 1M LiPF6 as the electrolyte. was used (the EC, EMC, and DEC were mixed in a weight ratio of 3: 4: 3 in order, and 2% by weight of VC (Vinyl Carbonate) was added to the mixture).

Comparative Example 2

A half coin cell was manufactured in the same manner as in Example 13, except that the positive electrode active material of Comparative Example 1 was used as the positive electrode active material.

Reference example 2

A half coin cell was manufactured in the same manner as in Example 13, except that the positive electrode active material of Reference Example 1 was used as the positive electrode active material.

Evaluation Example 4. Electrochemical Characteristics Evaluation

The initial charge and discharge capacities of the half coin cells of Example 13, Comparative Example 2, and Reference Example 2 were measured using a charger/discharger (WBCS3000L, Wonatech). At this time, the measurement was performed under conditions of a voltage range of 4.2 to 2.5 V and a constant current density of 0.1 C.

As a result, a graph like that of FIG. 5 was derived.

Specifically, in the case of Reference Example 2, a charging capacity of 136.73 mAh/g was exhibited, in the case of Comparative Example 2, a charging capacity of 111.75 mAh/g was exhibited, and in the case of Example 13, a charging capacity of 177.26 mAh/g showed up

In the case of Example 13, in which lithium loss, structural change, and surface by-product formation of the positive electrode active material were restored according to the present invention, it had a higher capacity value than Comparative Example 2 using the deteriorated positive electrode active material, and even pristine positive electrode active material It was confirmed that it had a higher capacity value compared to the used Reference Example 2.

Claims (13)

A method for recovering and restoring a positive electrode active material, in which the positive electrode desorption step and the lithium insertion step are performed at the same time.
The method of claim 1, wherein the cathode desorption step and lithium insertion step are performed in a solution containing a lithium precursor.
The method of claim 2, wherein the lithium precursor is lithium acetate, lithium nitrate, lithium sulphate, lithium perchlorate, lithium hydroxide and lithium chloride (LiCl). At least one selected from the group consisting of, positive electrode active material recovery and restoration method.
The method of claim 2, wherein the lithium precursor is contained within the range of 0.01 mol/L to 10 mol/L in the solution.
The method of claim 2, wherein the solution containing the lithium precursor is ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, hexylene glycol and 1,2- glycol solvents including hexadecanediol (1,2-hexadecanediol); or methyl glycol, butyl glycol, butyl triglycol, butyl polyglycol, hexyl glycol, hexyldiglycol, ethylhexylglycol, ethylhexyldiglycol, arylglycol, phenylglycol, phenyldiglycol, benzyl glycol, methylpropylene glycol, methylpropylene One or two selected from the group consisting of glycol ether solvents including diglycol, methyl propylene triglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol, butyl propylene diglycol, phenyl propylene glycol and methyl propylene glycol acetate A method for recovering and restoring a positive electrode active material formed by dissolving the lithium precursor in a solvent that is a mixture of more than one species.
The method of claim 1, wherein the cathode desorption step and the lithium insertion step include a heat treatment step.
The method of claim 6, wherein the heat treatment is performed within a temperature range of 100 °C to 300 °C.
The method of claim 6, wherein the heat treatment is performed within a time range of 1 minute to 120 minutes.
The method for recovering and restoring a positive electrode active material according to claim 1, comprising additional heat treatment and adding lithium.
10. The method of claim 9, wherein the additional heat treatment and adding lithium are performed at a temperature in the range of 400 °C to 1200 °C.
According to claim 1, To the positive electrode active material recovery and restoration method further comprising the step of recovering the positive electrode scrap from the waste battery.
The method of claim 1, further comprising the step of centrifuging.
The method of claim 1 , further comprising a drying step.

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