KR20170052012A - Recycling method for waste electrode of lithium secondary battery - Google Patents

Abstract

The present invention relates to a method for manufacturing a lithium secondary battery, comprising the steps of: (1) sorting a lithium secondary battery active material slurry, electrode or electrode assembly, which is generated in a process for producing a lithium secondary battery, (2) immersing the crushed material in an acid to leach the active material to obtain an active material leaching solution; (3) analyzing the components of the leach solution; (4) correcting the leach solution to an optimal composition ratio; And (5) a step of recycling the corrected leachate into a raw material and inputting the recycled leachate into a production process of an active material. The present invention relates to a recycling method of a waste lithium secondary battery electrode of the present invention According to the present invention, the active material component can be recovered from an electrode or an electrode assembly for a lithium secondary battery that is less than standard in the process of manufacturing a lithium secondary battery and can be recycled immediately in the manufacturing process of the lithium secondary battery. This method can be used effectively.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycling method of a waste lithium secondary battery electrode in a manufacturing process of a lithium secondary battery,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recycling a waste lithium secondary battery electrode in a manufacturing process of a lithium secondary battery, and more particularly, to a method of recycling an electrode for a lithium secondary battery, will be.

As technology development and demand for mobile devices have increased, there has been a rapid increase in demand for secondary batteries as energy sources. Among such secondary batteries, lithium secondary batteries, which exhibit high energy density and operating potential, long cycle life, Batteries have been commercialized and widely used.

The lithium secondary battery generally comprises a positive electrode containing a positive electrode active material, a negative electrode including a negative electrode active material, a separator and an electrolyte, and is charged and discharged by intercalation-decalation of lithium ions. The lithium secondary battery has a high energy density, a large electromotive force, and a high capacity, so it is applied to various fields.

The positive electrode active material of the lithium secondary battery contains a transition metal such as cobalt together with lithium. The lithium and cobalt are relatively expensive metals. In particular, cobalt is known as an unstable supply / have. Therefore, when the recovered transition metal, such as lithium and cobalt, is recovered from the discarded electrode, especially the anode, as a raw material, not only price competitiveness can be secured but also additional profit can be created.

Meanwhile, in order to recover lithium and cobalt and other transition metals from the waste electrode and recycle them, a transition metal such as lithium and cobalt is separated from the waste electrode, purified, and then used as a raw material for the production of a cathode active material It must be transformed into a suitable form for use. For example, Japanese Patent Application Laid-Open No. 2000-0055084 discloses a method comprising burning a lithium transition metal oxide, dissolving the lithium transition metal oxide in an acid, adding a carboxylic acid salt to precipitate, and then drying and pyrolyzing the precipitate. Since the method of the patent document includes a step of generating a precipitate and pyrolyzing it to transform the transition metal component into a recyclable form, even after the transition metal component is extracted, considerable energy and time for separation of components It is necessary to take the time required for the operation.

Therefore, if a method for directly utilizing the transition metal component for the production of the active material of the lithium secondary battery is developed without any separate process for separating the transition metal component as described above, the waste electrode can be recycled through a simpler and more efficient method It is expected.

It is an object of the present invention to provide a method for recycling an electrode or an electrode assembly for a lithium secondary battery which is incapable of being produced in a manufacturing process of a lithium secondary battery and for recycling a waste lithium secondary battery electrode.

In order to solve the above problems,

(1) separating a lithium secondary battery active material slurry, an electrode, or an electrode assembly, which is generated in a manufacturing process of a lithium secondary battery, to obtain a crushed product;

(2) immersing the crushed material in an acid to leach the active material to obtain an active material leaching solution;

(3) analyzing the components of the leach solution;

(4) correcting the leach solution to an optimal composition ratio; And

(5) a step of converting the corrected leached liquid into a raw material and inputting the leached raw material to a manufacturing process of the active material

The present invention also provides a method for recycling a waste lithium secondary battery electrode.

According to the recycling method of a waste lithium secondary battery electrode of the present invention, an active material component is recovered from an electrode or an electrode assembly for a lithium secondary battery which is generated in a manufacturing process of a lithium secondary battery and is under the standard, It can be recycled and thus can be usefully used as a recycling method for waste lithium secondary battery electrodes.

FIG. 1 is a flow chart showing each step according to a recycling method of a waste lithium secondary battery electrode of the present invention.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be interpreted in the meaning and concept consistent with the technical idea of the present invention.

The method for recycling a waste lithium secondary battery electrode of the present invention comprises the steps of: (1) sorting an active material slurry, electrode or electrode assembly for a lithium secondary battery that is less than the standard size generated in the process of manufacturing a lithium secondary battery, ; (2) immersing the crushed material in an acid to leach the active material to obtain an active material leaching solution; (3) analyzing the components of the leach solution; (4) correcting the leach solution to an optimal composition ratio; And (5) converting the corrected leached liquid into a raw material and inputting the leached raw material into a manufacturing process of the active material.

(1) separating the lithium secondary battery active material slurry, electrode or electrode assembly, which is generated in the manufacturing process of the lithium secondary battery, and breaking the same to obtain a crushed product

In step (1), the lithium secondary battery active material slurry, electrode, or electrode assembly, which is generated in the manufacturing process of the lithium secondary battery, is classified and collected.

The active material slurry may fail to control the composition and physical properties of the slurry containing the active material and may be less than the predetermined standard. In addition, the slurry may be a waste slurry or the like other than the active material slurry coated on the electrode surface have.

The electrode may be a coating failure of the active material slurry during coating or an electrode which is less than the standard size or an electrode having an expiration time set in storage of the completed electrode.

The electrode assembly may be an object to be discarded due to an amount exceeding a set standard or a moisture content.

The method may further include separating the electrode assembly into an anode, a cathode, and a separation membrane before the electrode assembly is crushed when the collected and collected object is the electrode assembly. If the electrode assembly includes metal lithium, the electrode assembly may be subjected to a heat treatment prior to separating the electrode assembly into an anode, a cathode, and a separator. The heat treatment may be performed at 100 to 150 ° C for about 10 minutes to 1 hour. When the electrode assembly includes metal lithium, the metal lithium may be converted into an oxide form through the heat treatment to stabilize the metal lithium.

The electrode for a lithium secondary battery may be a positive electrode or a negative electrode, but may be an anode having a large benefit in recycling the active material from the viewpoint of economy.

For the same reason, even in the electrode assembly, only the positive electrode can be classified and recycled. Therefore, in the case where the step of obtaining the crushed product in the example of the present invention is performed using the electrode assembly, May be further included.

Meanwhile, the electrode separated from the active material slurry, the electrode for a lithium secondary battery, or the electrode assembly can be calcined as needed, and the organic material such as a binder contained in the electrode through the calcination May be burnt and removed. The calcination may be performed at a temperature of 100 to 500 ° C, specifically 100 to 400 ° C, for 10 minutes to 3 hours.

The electrode thus classified and crushed as necessary is crushed to form a crushed product.

The crushing can be done by milling and the milling can be a mechanical milling, and in particular a roll mill, a ball mill, a jet mill, a planetary mill, -mill, and attrition-mill, for example. In this case, when the object to be crushed is an active material slurry, or when the active material in the crushed material obtained by crushing the electrode or the electrode assembly is further crushed, an induction mill may be used. In the wet crushing using the impact mill, The efficiency can be increased.

The milling may be performed for 1 to 8 hours, preferably for 1 to 6 hours.

The pulverized product may have a particle diameter of 1 to 10 mu m, specifically, a particle diameter of 2 to 7 mu m, more specifically, a particle diameter of 2 to 5 mu m.

When the particle size of the crushed material is 1 占 퐉 or more, the electrode current collector included in the crushed material can prevent the crushed material from being excessively eluted during the immersion of the crushed material in the acid, When the particle size of the crushed product is 10 m or less, the active material components are more effectively leached in the process of immersing the crushed product in the acid, so that the yield according to the recycle can be increased.

(2) immersing the crushed material in an acid to leach the active material to obtain an active material leaching solution;

In step (2), the impurities obtained in step (1) are immersed in an acid to leach the active material from the crushed product to obtain an active material leaching solution in which the active material component is dissolved.

The acid may be at least one member selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid, and may be an aqueous acid solution.

The immersion may be performed while the acid is heated to a temperature of 30 to 100 DEG C, specifically, a temperature in the range of 50 to 90 DEG C so that the active material can be more easily leached from the crushed product.

The acid may be used in an equivalence ratio of 1 to 5 equivalents, specifically 1.5 to 3 equivalents, relative to the transition metal contained in the active material.

When the crushed material is immersed in an acid, a metal component derived from the electrode current collector included in the crushed material can be dissolved together. Therefore, the active material is effectively leached while minimizing the dissolution of components derived from the electrode current collector It is necessary to adjust the pH of the acid. The pH of the acid may be 0 to 4, and may be 0.5 to 2 in particular.

The leaching time may be from 30 minutes to 300 minutes, and specifically from 60 minutes to 180 minutes. Since the crushed material has a particle diameter of 1 탆 to 10 탆 by milling, the active material can be more effectively leached, so that leaching can be performed within a relatively short time of 60 to 180 minutes. If the time is shorter than the above range, If the time is longer than the above range, a large amount of metal components derived from the electrode current collector in the crushed product may be leached together.

When the catalytic agent is added during the leaching, an exothermic reaction is caused to increase the leaching rate and leaching efficiency. The catalyst may be specifically hydrogen peroxide (H ₂ O ₂ ) and may be used in an amount of 0.1 to 10% by weight, specifically 0.5 to 5% by weight, based on the total weight of the leach solution.

The active material leaching solution obtained through the above-mentioned method includes a salt of lithium and a transition metal contained in the active material, and may optionally contain a small amount of an electrode current collector metal component. When the active material leaching solution contains a small amount of the electrode collector metal component, the metal component may be aluminum used as a collector of the positive electrode among metal components derived from the electrode collector, May include not more than about 0.5 wt% aluminum, and more specifically not more than about 0.5 wt% aluminum.

(3) analyzing the components of the leach solution

When the active material leachate is obtained through the leaching process, the components of the leachate are analyzed next.

The component analysis can be performed through, for example, an ICP mass spectrometry or an ICP emission spectrometry, and specifically, a more accurate component analysis result can be obtained by using the ICP mass spectrometry.

The method for recycling a lithium secondary battery according to an exemplary embodiment of the present invention may further include a step of removing impurities contained in the leach solution after the component analysis of step (3) After the analysis, the process may further include a step of removing impurities contained in the leach solution.

The removal of the impurities can remove the lithium and transition metal components contained in the active material, that is, the metal components derived from the electrode current collector, and the impurity removal can control the pH of the leaching solution . The pH may be from 5 to 7, and specifically from 5.5 to 6.5.

By controlling the pH to a range of 5.5 to 6.5, impurities can be removed by a method of precipitating metal components originating from an electrode current collector such as Al or Cu.

The method for recycling a lithium secondary battery according to an exemplary embodiment of the present invention may further include a step of performing purification and separation after the component analysis in the step (3) May be further included.

The purification may be performed by controlling the pH of the leaching solution to remove impurities contained in the leaching solution, and separating the solution once or several times, similar to the process of removing the impurities.

The fine particulate by-product (aluminum or the like) precipitated in the leach solution through the purification and separation process may be finally filtered to obtain a pure filtrate.

The separation can be carried out by a method of filtrating impurities in the form of precipitate and solid impurities suspended in solid phase using a solid-liquid separation method.

The genital solid-liquid separation method may include a step of filtering the leach solution having the particulate by-products sufficiently dispersed in advance by using a filter connected to a vacuum pump or the like. Through the filtration, the impurities floating in the impurities and the solid phase can be filtered through the filter paper including micropores.

The filtration may be repeated several times, specifically about 3 to 5 times, through which a pure filtrate can be obtained.

(4) correcting the leach solution to an optimal composition ratio

After the analysis of the components of the leach solution, the leaching solution is subjected to a step of correcting the optimum composition ratio so that it can be directly used as a raw material in the process of manufacturing the active material in the production process of the lithium secondary battery.

Specifically, the correction of the step (4) is performed such that the content of the metal salt of the metal component constituting the active material contained in the leach solution is stoichiometrically matched with the composition of the active material produced in the production process of the lithium secondary battery Process.

In the adjustment process, an insufficient active component among the individual active material components contained in the leach solution is added and corrected according to the result of the component analysis in the step (3). For example, the leaching solution includes cobalt sulfate, nickel sulfate, manganese sulfate If the amount of cobalt sulfate relative to the composition of the cathode active material used in the production process of the lithium secondary battery is insufficient, correction may be performed by adding cobalt sulfate separately to the composition of the cathode active material .

The corrected leach liquor, which has been corrected through the adjustment process, may contain a raw material of an active material included in a lithium secondary battery to be manufactured, particularly, a raw material of a cathode active material. Specifically, lithium sulfate, nickel sulfate, manganese sulfate, At least one selected from the group consisting of cobalt sulfate, cobalt sulfate, lithium nitrate, nickel nitrate, manganese nitrate, cobalt nitrate, lithium chloride, nickel chloride, manganese chloride and manganese chloride.

(5) a step of converting the corrected leached liquid into a raw material and inputting the leached raw material to a manufacturing process of the active material

The corrected leach liquor obtained through the above steps is re-raw material and is put into the process of manufacturing the active material in the manufacturing process of the lithium secondary battery, and the corrected leach liquor is directly mixed with the raw material for producing the active material To be recycled.

The method of recycling a waste lithium secondary battery electrode of the present invention separates an active material from an electrode or an electrode assembly for a lithium secondary battery that is not produced in the process of manufacturing the lithium secondary battery and uses the same to manufacture a lithium secondary battery Therefore, the electrode or the electrode assembly for a defective lithium secondary battery can be more effectively and easily recycled, thereby achieving cost reduction and environmental preservation effects.

When the recycling method of the waste lithium secondary battery electrode of the present invention is applied to a lithium secondary battery electrode which is not standardized, the anode may be manufactured by a conventional method known in the art. For example, the slurry may be prepared by preparing a slurry by mixing and stirring a solvent, a binder, a conductive material, and a dispersant, if necessary, in a cathode active material, applying the slurry to a current collector of a metal material, .

The current collector of the metal material is a metal having high conductivity and is a metal which can easily adhere to the slurry of the cathode active material and is not particularly limited as long as it has high conductivity without causing chemical change in the battery in the voltage range of the battery But may be, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or surface treated with aluminum, stainless steel or carbon, nickel, titanium or silver. The current collector may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric, and may have a thickness of 3 to 500 μm.

The cathode active material is preferably a layered compound such as lithium cobalt oxide [Li _x CoO ₂ (0.5 <x <1.3)], lithium nickel oxide [Li _x NiO ₂ (0.5 <x <1.3)], compound; Lithium manganese oxides such as LiMnO ₃ , LiMn ₂ O ₃ , or [Li _x MnO ₂ (0.5 <x <1.3)], such as Li _{1 + x} Mn _{2 - x} O ₄ where x is 0 to 0.33; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , or Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide represented by the formula LiNi _{1 - x} M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2 - x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 to 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like.

When the recycling method of the waste lithium secondary battery electrode of the present invention is applied to a negative electrode for a lithium secondary battery that does not meet the standard, the negative electrode may be manufactured by a conventional method known in the art. For example, the negative electrode active material may be prepared by mixing and stirring a solvent, a binder, a conductive material, and a dispersant, if necessary, to prepare a slurry, coating the negative electrode current collector with the negative electrode current collector, compressing and drying the slurry.

The negative electrode current collector is not particularly limited as long as it has electrical conductivity without causing a chemical change in the battery. The negative electrode current collector may be formed on the surface of copper, gold, stainless steel, aluminum, nickel, titanium, sintered carbon, Carbon, nickel, titanium, silver or the like, an aluminum-cadmium alloy, or the like. The current collector may be in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a nonwoven fabric, and may have a thickness of 3 to 500 μm.

The negative electrode active material used for the negative electrode may be a carbonaceous material, lithium metal, silicon, tin, or the like, from which lithium ions can be occluded and released. The carbon material may preferably be low carbon and high crystal carbon. Examples of the low crystalline carbon include soft carbon and hard carbon. Examples of highly crystalline carbon include natural graphite, kish graphite, pyrolytic carbon, liquid crystal pitch carbon fiber high-temperature sintered carbon such as mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches and petroleum or coal tar pitch derived cokes.

When the recycling method of the waste lithium secondary battery electrode of the present invention is applied to an electrode separated from an electrode assembly that is not standardized, the electrode assembly may have a separation membrane interposed between the anode and the cathode.

The separation membrane may be a conventional porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene-butene copolymer, an ethylene-hexene copolymer, and an ethylene-methacrylate copolymer Or a laminate thereof, or may be a nonwoven fabric made of a conventional porous nonwoven fabric, for example, a high melting point glass fiber, a polyethylene terephthalate fiber or the like, but is not limited thereto.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Experimental Examples, but the present invention is not limited by these Examples and Experimental Examples. The embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example

<Pretreatment process>

The waste active material slurry and the waste electrode are dried and then heat treated at (100 to 400) ° C to burn off the organic material. The waste electrode assembly removes parts such as separation membrane and other attached tapes and tabs, Like the electrode, it is heat treated at (100 to 400) ℃ to burn out the organic matter.

<Crushing>

The pretreated waste active material slurry, the waste electrode and the waste electrode assembly are pulverized using a mill (dry pulverization). At this time, wet grinding using an induction mill is further carried out in order to crush the waste active material slurry.

The pulverization process can be performed until the particle size of the pulverized product becomes 1 to 10 μm through particle size measurement (PSD), and the large particles are filtered through a sieving process after the pulverization.

<Wet Leaching>

Crushed crushed material is added to a sulfuric acid solution having a pH of 0 to 4 and stirred to cause the active material to be leached. The sulfuric acid solution charged with the crushed product is heated to a temperature of 60 to 80 캜 and leached for 30 to 300 minutes. At this time, hydrogen peroxide solution as a catalyst was added to the sulfuric acid solution in an amount of 1.5 wt% based on the total amount of the sulfuric acid solution. When the leaching is completed, the solution is filtered to obtain a filtrate (leach solution).

<Component analysis>

ICP analysis analyzes the content of components present in the solution (such as Ni, Co, Mn) and analyzes the content of impurities (Al, Cu, etc.) to determine the purity of the leach solution.

<Impurity Control>

The pH is adjusted to 5 to 7 to precipitate impurities. Since the leach solution is an acidic solution, impurities (Al, Cu, etc.) can be precipitated by increasing the pH by adding a basic substance such as NaOH.

<Purification and Separation>

The precipitate is separated through filtration to obtain a pure filtrate. If necessary, the components of the filtrate are subjected to secondary analysis to re-measure the content of Ni, Mn, Co, and the like.

<Optimum Composition Ratio Correction>

The composition of the active material targeted for production is compared with the content of each component analyzed in the previous step so that the composition of the filtrate is adjusted to the optimum composition ratio so as to match the composition of the active material to be produced. For example, when the content of Ni in the transition metal is 50% and the measured value of the Ni metal contained in the filtrate is 48%, nickel sulfate or the like may be further dissolved by 2% to compensate for the target active material.

<Re-raw materialization>

The solution corrected to the optimal composition ratio is recycled as the raw material for the cathode active material. After the precursor is prepared from the corrected solution, it is synthesized into a cathode active material. If a waste active material is generated, the process from the pre-treatment is repeated to recycle the precursor.

Claims (18)

(1) separating a lithium secondary battery active material slurry, an electrode, or an electrode assembly, which is generated in a manufacturing process of a lithium secondary battery, to obtain a crushed product;
(2) immersing the crushed material in an acid to leach the active material to obtain an active material leaching solution;
(3) analyzing the components of the leach solution;
(4) correcting the leach solution to an optimal composition ratio; And
(5) a step of converting the corrected leached liquid into a raw material and inputting the leached raw material to a manufacturing process of the active material
And recycling the waste lithium secondary battery electrode.
The method according to claim 1,
Wherein the electrode for the lithium secondary battery is a positive electrode for a lithium secondary battery.
The method according to claim 1,
The method of recycling a waste lithium secondary battery electrode according to claim 1, wherein, in the step (1), when the step of obtaining the crushed product is performed using the electrode assembly, separating the anode from the electrode assembly.
The method according to claim 1,
A method for recycling a waste lithium secondary battery electrode, wherein the crushing in the step (1) is performed by milling.
5. The method of claim 4,
Wherein the milling is carried out by using at least one member selected from the group consisting of a roll-mill, a ball-mill, a jet-mill, a planetary-mill and an attrition- And recycling the waste lithium secondary battery electrode.
The method according to claim 1,
Wherein the pulverized product has a particle diameter of 1 占 퐉 to 10 占 퐉.
The method according to claim 1,
Wherein the acid is at least one selected from the group consisting of sulfuric acid, nitric acid, and hydrochloric acid.
The method according to claim 1,
Wherein said acid has a pH of from 0 to 4. &lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt;
The method according to claim 1,
Wherein the leaching is performed at a temperature of 30 to 100 占 폚.
The method according to claim 1,
Wherein the leaching is performed for 30 minutes to 300 minutes.
The method according to claim 1,
Wherein the active material leaching solution contains 1 wt% or less of aluminum.
The method according to claim 1,
Wherein the analysis of step (3) is performed by a CP mass spectrometry method or an ICP emission spectrometry method.
The method according to claim 1,
Further comprising the step of removing impurities contained in the leach solution after analyzing the components of step (3).
14. The method of claim 13,
Wherein the impurity removal is performed by adjusting the pH of the leaching solution.
15. The method of claim 14,
Wherein the pH is 5 to 7. The method of recycling a waste lithium secondary battery electrode according to claim 1,
15. The method of claim 14,
The method of recycling a waste lithium secondary battery electrode further comprising the step of purifying and separating after the component analysis of step (3).
The method according to claim 1,
The correction of the step (4) is a process of adjusting the content of the metal salt of the metal component forming the active material contained in the leach solution to be stoichiometrically matched with the composition of the active material produced in the production process of the lithium secondary battery, Recycling method of waste lithium secondary battery electrode.
The method according to claim 1,
The method according to any one of claims 1 to 5, wherein in the step (5), the corrected leaching solution comprises at least one of lithium sulfate, nickel sulfate, manganese sulfate, cobalt sulfate, lithium nitrate, Wherein at least one selected from the group consisting of lithium,

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