Apparatus for recovering active material and method for reusing active material by using same

Abstract

APPARATUS FOR RECOVERING ACTIVE MATERIAL AND METHOD FOR REUSING ACTIVE MATERIAL BY USING SAME. An active material recovery apparatus capable of easily recovering an electrode 5 active material from an electrode scrap in its intrinsic shape and a positive electrode active material reuse method using the active material recovery apparatus are provided. The active material recovery apparatus which is a rotary firing apparatus comprising a rod in a screw type therein includes a heat treatment bath and a screening wall arranged in a line along an axis of the rod, wherein the heat treatment bath constitutes a heating zone, and the 10 screening wall constitutes a cooling zone; and an exhaust injection and degassing system, wherein the heat treatment bath removes a binder and a conductive material in an active material layer by performing heat treatment on an electrode scrap comprising the active material layer on a current collector in an air while rotating the electrode scrap around the axis of the rod and separates the current collector from the active material layer, and an active 15 material in the active material layer passes through the screening wall and is recovered as an active material in powder form, and the current collector that does not pass through the screening wall is recovered separately.

Description

TECHNICAL FIELDThe present disclosure relates to a method of recycling resources whenmanufacturing a lithium secondary battery. In particular, the present disclosure relates toan apparatus for recovering an electrode active material from an electrode scrap generatedin a lithium secondary battery manufacturing process or from a lithium secondary batterythat is discarded after use, and a method of reusing the recovered active material. The presentapplication claims priority to Korean Patent Application No. 10-2020-0101962 filed onAugust 13, 2020 in the Republic of Korea, the disclosure of which is incorporated herein byreference.BACKGROUND ARTLithium secondary batteries which may be repeatedly charged and discharged are inthe spotlight as an alternative to fossil energy. Lithium secondary batteries have beenmainly used in traditional handheld devices such as cell phones, video cameras, and powertools. However, recently, application fields of lithium secondary batteries have beengradually increasing to electric vehicles (EVs, HEVs, and PHEVs), large capacity energystorage systems (ESSs), uninterruptible power supply systems (UPS), etc.A lithium secondary battery includes an electrode assembly in which unit cellshaving a structure in which a positive electrode plate and a negative electrode plate coatedwith an active material on a current collector are arranged with a separator interposedtherebetween, and an exterior material sealing and accommodating the electrode assemblytogether with an electrolyte, that is, a battery case. The positive electrode active materialof the lithium secondary battery mainly uses a lithium-based oxide, and the negativeelectrode active material uses a carbon material. The lithium-based oxide contains a metalsuch as cobalt, nickel, or manganese. In particular, cobalt, nickel, and manganese are veryexpensive valuable metals. Among these, cobalt is a strategic metal, and each country inthe world has a special interest in supply and demand of cobalt. Since the number of cobaltproducing countries is limited, it is known as a metal whose supply and demand is unstableworldwide. If an imbalance in the supply and demand of raw materials of strategic metalsoccurs, raw material prices are highly likely to rise.Conventionally, research on recovering and recycling these valuable metals fromlithium secondary batteries (waste batteries) which are discarded when their lifespan iscompleted after use has been mainly conducted. In addition to waste batteries, it is morepreferable if resources may be recovered from wastes discarded after the positive electrodeplate is punched or from the positive electrode in which a defect occurs during the process.Currently, when manufacturing a lithium secondary battery, as shown in FIG. 1, apositive electrode sheet 30 is manufactured by forming a positive electrode active materiallayer 20 in which a long sheet type positive electrode current collector 10 such as aluminum(Al) foil is coated with a positive electrode slurry in which a positive electrode activematerial, a conductive material, a binder, a solvent, etc. are mixed, and then a positiveelectrode plate 40 is punched out with a certain size. A part remaining after punching isdiscarded as a positive electrode scrap 50. If it is possible to recover the positive electrodeactive material from the positive electrode scrap 50 and reuse the positive electrode activematerial, it would be very desirable from an industrial-economic point of view and anenvironmental point of view.Conventionally, in most cases, a method of recovering the positive active materialis performed by dissolving a positive electrode in hydrochloric acid, sulfuric acid, nitric acid,etc., and then extracting an active material element such as cobalt, nickel, manganese, etc.,and the extracted active material element is reused as a raw material for the synthesis of thepositive active material. However, the method of extracting the active material element usingan acid has disadvantages in that a process of recovering pure raw materials is notenvironmentally friendly as well as requires a neutralization process and a wastewatertreatment process, which increases the process cost. In addition, the method has adisadvantage in that lithium, which is one of the main elements of the positive electrodeactive material, may not be recovered. In order to solve these disadvantages, a method ofdirectly reusing the active material without dissolving the positive electrode active materialand extracting the active material in element form is required.DISCLOSURETechnical ProblemThe present disclosure is directed to providing an active material recovery apparatuscapable of easily recovering an electrode active material from an electrode scrap in itsintrinsic shape.The present disclosure is also directed to providing a positive electrode activematerial reuse method using the active material recovery apparatus.Technical SolutionIn one aspect of the present disclosure, there is provided an active material recoveryapparatus which is a rotary firing apparatus comprising a rod of a screw type therein includesa heat treatment bath and a screening wall arranged in a line along an axis of the rod, whereinthe heat treatment bath constitutes a heating zone, and the screening wall constitutes acooling zone; and an exhaust injection and degassing system, wherein the heat treatmentbath removes a binder and a conductive material in an active material layer by performingheat treatment in air on an electrode scrap comprising the active material layer on a currentcollector while rotating the electrode scrap around the axis of the rod, and separates thecurrent collector from the active material layer, and an active material in the active materiallayer passes through the screening wall and is recovered as an active material in powderform, and the current collector that does not pass through the screening wall is recoveredseparately.The heat treatment bath may also rotate around the axis of the rod.An angle of the entire active material recovery apparatus may be adjusted so thatthe axis is inclined with respect to a ground.The active material recovery apparatus may have a vibration function.Input of a new electrode scrap and recovery of the active material may becontinuously performed.Preferably, the heat treatment bath has a tubular shape with both ends open so thatthe electrode scrap is put therein and the separated current collector and active material aretransferred to the screening wall, and a tube is an open type system through which air entersand exits.Preferably, the screening wall has a tubular shape with both ends open so that theseparated current collector and active material are put therein and the current collector isdischarged.The heat treatment bath is preferably an open type system in which air of 10 mL / minto 100 L / min is added or injected per 100 g of the electrode scrap that is put in.Air inlets may be preferably formed in a plurality of places in the heat treatmentbath.In one aspect of the present disclosure, there is provided a positive electrode activematerial reuse method including preparing an active material recovery apparatus accordingto the present disclosure; putting a positive electrode scrap in a heat treatment bathcomprising a lithium composite transition metal oxide positive electrode active materiallayer on a current collector; removing a binder and a conductive material in the activematerial layer by performing heat treatment in air on the positive electrode scrap whilerotating the positive electrode scrap around an axis of a rod in the heat treatment bath andseparating the current collector from the active material layer; recovering an active materialin powder form that has passed through a screening wall; and annealing the active materialin the air at 400 to 1000°C to obtain a reusable active material.At this time, the heat treatment may be performed at 300 to 650°C. Heat treatmentmay be performed at 550°C as a temperature increase rate of 5°C / min for 30 minutes.A carbon component generated by carbonization of the binder or the conductivematerial may not remain on a surface of the recovered active material.The positive electrode active material reuse method may further include, before theannealing, cleaning the recovered active material with a lithium compound solution showingbasicity in an aqueous solution state. In that case, before the annealing, a lithium precursoris preferably added to the cleaned active material. The lithium compound aqueous solutionmay be prepared to contain a lithium compound more than 0% and equal to or less than 15%,and preferably uses LiOH. The cleaning may be performed within one hour. Thecleaning may be performed by impregnating the recovered active material in the lithiumcompound aqueous solution and at the same time stirring the recovered active material.For another example, the positive electrode active material reuse method mayfurther include, after the cleaning, obtaining the active material to which a lithium precursoris added and of which particles are adjusted, by mixing the cleaned active material with alithium precursor solution and spray drying the active material.The positive electrode active material reuse method may further include performingsurface coating on the annealed active material.The lithium precursor used in annealing may include at least one of LiOH, Li2CO3,LiNO3 and Li2O.The lithium precursor is added by an amount that may be added as much as a ratioof lithium lost compared to a ratio of lithium to other metals in a raw material active materialused in the active material layer. For example, the lithium precursor may be added by anamount of lithium added at a molar ratio of 0.001 to 0.4. Furthermore, the lithium precursormay be added by an amount of lithium that may be further added at a molar ratio of 0.0001to 0.1 with respect to 1:1 that is a molar ratio of lithium to other metals. A temperature ofthe annealing may exceed a melting point of the lithium precursor.The performing of the surface coating may include coating at least one of a metal,an organic metal and a carbon component on a surface in a solid or liquid method and thenperforming heat treatment at 100 to 1200°C.The reusable active material is represented by Chemical Formula 1 below,LiaNixMnyCozMwO2+δ(in Chemical Formula 1 above, M includes at least one selected from the groupconsisting of B, W, Al, Ti and Mg, 1<a≤1.1, 0≤x<0.95, 0≤y<0.8, 0≤ z<1.0, 0≤w≤0.1, -0.02≤δ≤0.02, and x+y+z+w=1.)The reusable active material may include content of fluorine (F) equal to or less than100 ppm.Advantageous EffectsAccording to the present disclosure, it is possible to provide an active materialrecovery apparatus capable of easily seceding an electrode active material from a currentcollector during heat treatment by increasing an air contact rate through introduction of arotary heat treatment bath and continuously separating the electrode active material from thecurrent collector.Using the active material recovery apparatus according to the present disclosure, itis possible to recover the positive electrode active material from the positive electrode scrap.This method may reuse a waste positive electrode active material such as a positive electrodescrap generated during a manufacturing process of a lithium secondary battery without usingan acid, and thus the method is eco-friendly. The method according to the presentdisclosure does not require a neutralization process or a wastewater treatment process,thereby relaxing environmental issues and reducing process costs.According to the present disclosure, the positive electrode active material may berecovered without an unrecoverable metal element. Since a current collector is notdissolved, the current collector may also be recovered. The method may directly reuse theactive material recovered in powder form, rather than extracting an active material elementand using the active material element as a raw material for synthesizing a positive electrodeactive material again, and thus the method is economical.According to the present disclosure, toxic and explosive solvents such as NMP,DMC, acetone, and methanol are not used, and thus the method is safe. Simple processessuch as heat treatment, cleaning, and annealing, etc., are used, and thus it is easy to managethe processes and the method is suitable for mass production.According to the present disclosure, the electrochemical performance of therecovered active material does not deteriorate, and excellent resistance and capacityproperties may be implemented.DESCRIPTION OF DRAWINGSThe accompanying drawings illustrate a preferred embodiment of the presentdisclosure and together with the foregoing disclosure, serve to provide further understandingof the technical features of the present disclosure, and thus, the present disclosure is notconstrued as being limited to the drawing.FIG. 1 is a diagram showing a positive electrode scrap discarded after a positiveelectrode plate is punched from a positive electrode sheet.FIG. 2 is a schematic diagram of an active material recovery apparatus according toan embodiment of the present disclosure.FIG. 3 is a schematic diagram of an active material recovery apparatus according toanother embodiment of the present disclosure.FIG. 4 is a flowchart of an active material reuse method according to anotherembodiment of the present disclosure.FIG. 5 is a flowchart of an active material reuse method according to anotherembodiment of the present disclosure.FIG. 6 is a picture showing a difference in heat treatment results according to alocation of a positive electrode scrap in Sample 1.FIG. 7 is a picture showing a state of Sample 2 by time according to an experimentalprocess.FIGS. 8 and 9 show results of cell evaluation using active materials of Embodiments1 and 2 and Comparative Examples 1 to 5.FIGS. 10 and 11 are scanning electron microscope (SEM) pictures of the activematerials of Embodiment 1 and Comparative Examples 1 to 3 and 5.FIG. 12 is a particle size distribution graph of active materials of Embodiments 3and 4 and Comparative Examples 1 and 2.FIG. 13 shows results of cell evaluation using the active materials of Embodiments3 and 4 and Comparative Example 1, and resultant values are summarized in Table 4.FIG. 14 shows results of cell evaluation using the active materials of Embodiment5 and Comparative Examples 6 to 9.FIG. 15 shows XRD patterns of active materials of Embodiment 5 and ComparativeExamples 6, 7, and 9.FIG. 16 is SEM pictures of the active materials of Embodiment 5 and ComparativeExample 6.FIG. 17 shows X-Ray Photoelectron Spectroscopy (XPS) patterns of activematerials of Comparative Examples 6, 7, and 9.FIG. 18 is a particle size distribution graph of the active materials of Embodiment 5and Comparative Examples 6, 7, and 9.FIG. 19 shows results of cell evaluation using active materials of Embodiment 6 andComparative Examples 6, 7, and 10.FIG. 20 shows XPS patterns of the active materials of Embodiment 6 andComparative Examples 6 to 8.BEST MODEHereinafter, preferred embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. Prior to the description, it should beunderstood that the terms used in the specification and the appended claims should not beconstrued as limited to general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the present disclosure on thebasis of the principle that the inventor is allowed to define terms appropriately for the bestexplanation. Therefore, the description proposed herein is just a preferable example for thepurpose of illustrations only, not intended to limit the scope of the disclosure, so it shouldbe understood that other equivalents and modifications could be made thereto withoutdeparting from the scope of the disclosure.In the following description, reference is made to the accompanying drawings,which form a part hereof. The illustrative embodiments described in the detailed description,drawings, and claims are not meant to be limiting. Other embodiments may be utilized,and other changes may be made, without departing from the sprit and scope of the subjectmatter presented herein. It will be readily understood that the aspects of the presentdisclosure, as generally described herein, and illustrated in the drawings, may be arranged,substituted, combined, separated, and designed in a wide variety of different configurations,all of which are explicitly contemplated herein.Unless defined otherwise, all technical and scientific terms used herein generallyhave the same meaning as commonly understood by one of ordinary skill in the art to whichthe disclosure belongs.The present disclosure is not to be limited in terms of the particular embodimentsdescribed in this application, which are intended as illustrations of various aspects. Manymodifications and variations can be made without departing from its spirit and scope, as willbe apparent to one of ordinary skill in the art. Functionally equivalent methods andapparatuses within the scope of the disclosure, in addition to those enumerated herein, willbe apparent to one of ordinary skill in the art from the foregoing descriptions. Suchmodifications and variations are intended to fall within the scope of the appended claims.The present disclosure is to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It is also to be understood thatthe terminology used herein is for the purpose of describing particular embodiments only,and is not intended to be limiting.In the case of the conventional active material recycling process, the main purposewas to extract valuable metals (nickel, cobalt, manganese, etc.) as elements in the lithiumsecondary battery active material whose performance has deteriorated after use andresynthesize the active material, whereas, there is a difference in that the present disclosurerecovers the active material from a positive electrode scrap generated during a lithiumsecondary battery manufacturing process.Furthermore, in the case of the already known active material recycling process, achemical method of extracting a valuable metal through acid / base dissolution or meltingusing reduction / additive, and manufacturing the valuable metal as a metal (a direct reductionmethod) or a resynthesized active material is added, which additionally incurs thecomplexity of process and the economic cost. However, the present disclosure relates to amethod of directly reusing a positive electrode active material without dissolving the positiveelectrode active material.In order to directly reuse the positive electrode active material, a method ofremoving a current collector from a positive electrode is required. To remove the currentcollector from the positive electrode, it is possible to remove a binder through hightemperature heat treatment, to melt the binder using a solvent, to completely melt the currentcollector, to select the active material through dry grinding and sieving, etc.The stability of the solvent is important in dissolving the binder using the solvent.Although NMP is the most efficient solvent, NMP has the disadvantages of toxicity and highprice. In addition, there is a disadvantage that a solvent recovery process such asreprocessing a waste solvent is required. Melting the current collector may be cheaper thanusing the solvent. However, since it is difficult to remove foreign substances from thesurface of the reuse active material and hydrogen gas is generated during a current collectorremoval process, there is a risk of explosion. It is difficult to completely separate thecurrent collector and the active material by dry grinding and sieving. Since the particle sizedistribution of active materials is changed during a grinding process, and it is difficult toremove the binder, there is a disadvantage in that the properties of a reused battery deteriorate.In the present disclosure, the active material and the current collector are separatedby high temperature heat treatment. In particular, an apparatus that performs heat treatmentin the air and is advantageous for mass production and commercialization is provided.Foreign substances should not remain on the surface of the reuse active material. In thepresent disclosure, even a step of removing foreign substances from the surface of the reuseactive material is proposed.Hereinafter, an active material recovery apparatus according to embodiments of thepresent disclosure is described with reference to FIGS. 2 and 3.First, an active material recovery apparatus 100 shown in FIG. 2 is a rotary firingapparatus including a rod 110 in a screw type therein.A heat treatment bath 120 and a screening wall 130 are arranged in a line along anaxis of the rod 110. The heat treatment bath 120 and the screening wall 130 may have ahollow tubular shape having a certain space in which an object to be treated may be contained.At this time, the rod 110 passes through the center of the heat treatment bath 120 and thescreening wall 130, the heat treatment bath 120 and the screening wall 130 may be coaxialarrangement. The rod 110 may have a long shape so as to be connected from one side tothe other side in the longitudinal direction of the heat treatment bath 120 and the screeningwall 130.The heat treatment bath 120 constitutes a heating zone, and the screening wall 130constitutes a cooling zone. The heat treatment bath 120 is installed at the front end of theapparatus in a transfer direction of the object to be treated, and the screening wall 130 isinstalled at the rear end of the apparatus. By sequentially installing the heat treatment bath120 and the screening wall 130, the object to be treated is sufficiently heated in the heattreatment bath 120 to cause thermal decomposition and then transferred to the screening wall130.The active material recovery apparatus 100 also includes an exhaust injection anddegassing system 140. Air or oxygen may be injected into the heat treatment bath 120using the exhaust injection and degassing system 140. Exhaust gas after heat treatmentmay be purified using the exhaust injection and degassing system 140 and then discharged.The rod 110 rotates along the axis thereof. The object to be treated is an electrodescrap 160, and preferably a positive electrode scrap. The electrode scrap 160 includes anactive material layer on a current collector 150. The heat treatment bath 120 removes abinder and a conductive material in the active material layer by performing heat treatmenton the electrode scrap 160 in the air while rotating the electrode scrap 160 around the axisof the rod 110. Heat treatment may be performed at 300 to 650°C, and thus may also becalled high temperature heat treatment. At a temperature less than 300°C, there is aproblem in that it is difficult to remove the binder so that the current collector 150 may notbe separated. At a temperature equal to or greater than 650°C, a phenomenon occurs thatthe current collector 150 melts (Al melting point: 660°C) and may not be separated. Whenthermal decomposition occurs sufficiently and the binder is removed, the active materiallayer may be separated from the current collector 150. The heat treatment bath 120 mayalso rotate around the axis of the rod 110. At this time, the rotational direction of the heattreatment bath 120 may be the same as or opposite to the rotational direction of the rod 110.The rotational direction of the heat treatment bath 120 may be changed at an appropriatetime interval.The rotation of the rod 110 and / or the heat treatment bath 120 leads to the rotationof the electrode scrap 160. In particular, the rod 110 pushes the electrode scrap 160 whilestirring the electrode scrap 160, which helps the electrode scrap 160 to be in good contactwith the air and the active material layer to be separated as the active material 170 in powderform by a stirring force. When only the heat treatment bath 120 is rotated, there is a highpossibility that the electrode scrap 160 including heavy metal components is not rotated welland is piled up only in the lower part of the inside of the heat treatment bath 120. Thenthere is less contact of oxygen or air. In the present disclosure, the electrode scrap 160 maybe stirred by rotating the rod 110 inside of the heat treatment bath 120. Even if the electrodescrap 160 is not put in by fine shredding, the electrode scrap 160 may be split by the rod 110.The split electrode scrap 160 is rotated by the rod 110 so that the split electrode scrap 160may sufficiently contact oxygen or air. The rod 110 does not simply rotate but is a screwtype, and thus the rod 110 has a protruding structure such as a pin, a wing, or a stick. Thisprotruding structure maximizes the rotation and mixing of the electrode scrap 160.Accordingly, an incomplete combustion due to an overlapping phenomenon betweenelectrode scraps may be eliminated.The active material layer separated from the current collector 150 through heattreatment in the heat treatment bath 120 may have a structure such as individual particles orflakes in which particles are agglomerated, and since an active material is not in a continuousfilm state, the active material is referred to as having powder form in the present disclosure.As such, in the heat treatment bath 120, the active material in powder form may be obtainedfrom the current collector 150 by simple heat treatment in the air, and some electrode scraps160 may be transferred to the screening wall 130 in a state in which the active material layeris attached onto the current collector 150 only by van der Waals force, or some activematerial layers are detached to become the active material 170 in powder form.It is preferable that the heat treatment bath 120 has a tubular shape with both endsopen so that the electrode scrap 160 is put therein and the current collector 150 from whichthe binder and the conductive material are removed and the active material 170 aretransferred to the screening wall 130. And, it is preferable that a tube is an open type systemthrough which air enters and exits. That is, since the tube does not have a closed structure,oxygen in the outside air may be introduced.The heat treatment bath 120 includes a container that receives, rotates, and mixesthe electrode scrap 160, and a heating unit capable of heat treating the electrode scrap 160by adding heat to the container. The container may be made of a metal or ceramic material.In particular, if the container is made of the ceramic material, corrosion due to the reactionwith the active material may be prevented, and contamination of the active material by metalions generated from the container may also be prevented. In addition, a heat source suchas a microwave may also be used as the heating unit, and thus types of available heat sourcesare diversified.For example, the container of the heat treatment bath 120 may be a tube made of aceramic material, for example, high purity alumina. And since such a tube further includesflanges connecting in the longitudinal direction at both ends of the tube, the heat treatmentbath 120 capable of large capacity processing may be manufactured by connecting two ormore tubes to each other and extending the length. In general, it is very difficult tomanufacture the tube made of the ceramic material over a certain diameter and a certainlength due to the characteristics of the material, and the product price of the tube is quitehigh. Accordingly, a plurality of tubes made of the ceramic material and having suitablediameters and lengths may be connected to a desired length through the flange, and largecapacity processing is possible by manufacturing the tubes to a length, for example, equal toor more than hundreds of mm or thousands of mm.The heating unit may be provided on an outer circumferential surface of thecontainer. For example, the heating unit is a linear heating element, and the heatingelement has a long bar shape so as to be connected from one side in the longitudinal directionof the container to the other side, and may be disposed on the outer circumferential surfaceof the container. Then, heat of a uniform temperature may be generated in the longitudinaldirection of the container. The heating element may include at least one selected from thegroup consisting of SiC, graphite, carbon nanotubes, carbon nanofibers, and graphene, andmay preferably be formed of a SiC material.The heat treatment bath 120 is preferably an open type system in which air of 10mL / min to 100 L / min is added or injected per 100 g of the electrode scrap 160 that is put in.If the heat treatment bath 120 has a tubular shape with both ends open, an addition of air issmooth. In addition, as shown by arrows in FIG. 2, when air inlets are installed in aplurality of places in the heat treatment bath 120, since air or oxygen injected through theexhaust injection and degassing system 140 is smoothly supplied in a part where theelectrode scrap 160 is mixed, a sufficient supply of air and oxygen necessary for thermaldecomposition into the heat treatment bath 120 is possible. The air inlets may be installedeven in the rod 110.When the electrode scrap 160 is heat treated, PVdF (polyvinylidene fluoride) and aconductive material present in the active material layer are decomposed and seceded fromthe current collector. However, if sufficient air and oxygen are not supplied, the activematerial layer is not separated from the current collector due to an incomplete combustion,but rather strongly carbonized and adheres to the current collector. In this case, since arecovery rate of the active material is reduced, it is difficult to secure fairness. The heattreatment bath 120 may control an addition amount of air and has a structure in which theelectrode scrap 160 is in good contact with air during heat treatment. In particular, in orderto recover a great amount of active material, the rod 110 rotates so that the electrode scrap160 is in good contact with the air, and the heat treatment bath 120 is also rotated so that theelectrode scrap 160 moves around inside of the heat treatment bath 120 to be evenly heatedand may be maximally in contact with the air. The incomplete combustion of elementsconstituting the active material layer may be suppressed, and thus the recovery rate of thefinally seceded active material may be increased. If air less than 10 mL / min is injected oradded per 100 g of the electrode scrap 160 that is put in, the binder and the conductivematerial are incompletely combusted, and thus the recovery rate of the active material isreduced. If air more than 100 L / min is injected or added, blowing of the active materialmay occur due to an excessive addition and temperature control may be difficult.The screening wall 130 may have a mesh structure. The size of a mesh may beappropriately determined so that the current collector 150 does not pass through thescreening wall 130. The active material 170 in powder form that has passed through thescreening wall 130 may be recovered through a first collector 180 installed in a lower partof the screening wall 130. The current collector 150 that has not passed through thescreening wall 130 may be recovered through a second collector 190 installed at the end ofthe screening wall 130. As described above, when the active material recovery apparatus100 is used, each of the active material 170 and the current collector 150 may be recovered.As described above, according to the active material recovery apparatus 100 of the presentdisclosure, the active material 170 may be recovered in its intrinsic shape, and the currentcollector 150 may also be recycled without melting or throwing away.The screening wall 130 preferably has a tubular shape with both ends open so thatthe separated current collector 150 and active material 170 are put therein and the currentcollector 150 is discharged. A detachment of the active material 170 from the currentcollector 150 is smooth through the rotation of the rod 110. The rod 110 rotates and stirsthe current collector 150 so that the active material 170 is detached from the current collector150 as well as the current collector 150 and the screening wall 130 collide with each otherso that the active material 170 comes off from the current collector 150 by the impact. Thescreening wall 130 may also be rotated around the axis of the rod 110. If the currentcollector 150 is in a stopped state because there is no rod 110 that rotates or the screeningwall 130 does not rotate, it is not easy for the active material 170 to come off from the currentcollector 150.The rotational direction of the screening wall 130 may be the same as or opposite tothe rotational direction of the rod 110. The rotational direction of the screening wall 130may be changed at an appropriate time interval. The screening wall 130 may also be thesame as the rotational direction of the heat treatment bath 120. When a connection partbetween the heat treatment bath 120 and the screening wall 130 is fixed, the heat treatmentbath 120 and the screening wall 130 may be rotated together. The heat treatment bath 120and the screening wall 130 may be configured as a prefabricated type connected to eachother or an integral type.For example, by forming coupling grooves along a main surface in one side of theheat treatment bath 120, and forming coupling protrusions along the main surface on oneside of the screening wall 130, ends of the heat treatment bath 120 and the screening wall130 corresponding to each other may be firmly connected through the coupling grooves andthe coupling protrusions. The coupling grooves and the coupling protrusions may becoupled through an interference fitting coupling method or a screw coupling method. Thecoupling grooves and the coupling protrusions may be coupled in a structure of a lockingprotrusion and a hook.As described above, when the heat treatment bath 120 and the screening wall 130are coaxially arranged in a tubular shape, it is preferable that the active material recoveryapparatus 100 continuously performs input of a new electrode scrap and recovery of theactive material.The screening wall 130 does not include merely the heating unit, and thus a coolingsection may be formed by using a slow cooling method of natural cooling, and cooling meansis further provided outside the screening wall 130, and thus a faster cooling method ortemperature-controlled cooling may be possible.It is preferable that the active material recovery apparatus 100 also has a vibrationfunction. Vibration may give a physical force so that the active material from which thebinder and the conductive material are removed after heat treatment secedes from the currentcollector. When vibration is applied, the active material 170 in the screening wall 130passes through the screening wall 130 and falls to the first collector 180 therebelow.Next, an active material recovery apparatus 100' shown in FIG. 3 is characterized inthat an angle θ of the entire active material recovery apparatus 100' is adjusted so that theaxis of the rod 110 is inclined with respect to the ground. As shown, the active materialrecovery apparatus 100' may be supported in a slightly inclined state so that the rear end ofthe active material recovery apparatus 100', that is, the right side in the drawing, is the lowerpart. Supports having different heights may be respectively installed at the front and rearlower portions of the active material recovery apparatus 100'.Adjustment of the angle θ gives an inclination to the ground, and the inclination mayallow the current collector 150 and the active material 170 to move downward by the weightsof the current collector 150 and the active material 170. As shown, when the inclination isgiven, the current collector 150 and the active material 170 move slowly from the left sideto the right side of the drawing through the heat treatment bath 120 and the screening wall130, the active material 170 in the screening wall 130 passes through the screening wall 130and falls to the first collector 180 below the screening wall 130, and the current collector150 that has not passed through the screening wall 130 falls to the second collector 190installed at the end of the screening wall 130. The angle θ may be maintained throughoutthe process in a state set before the process, or may be adjusted and changed as needed duringthe process.The active material recovery apparatuses 100 and 100' described above may processa large amount of electrode scraps, thereby greatly increasing work efficiency and reducingwork time. In particular, the active material recovery apparatuses 100 and 100' are opentype systems that do not block oxygen in the outdoor air and may supply sufficient air oroxygen for the complete combustion of the active material layer. The electrode scrap maybe rotated, which makes an air contact smoother, thereby recovering the active material witha uniform quality and a high recovery rate.Hereinafter, an active material reuse method according to embodiments of thepresent disclosure will be described with reference to FIGS. 4 and 5. First, FIG. 4 is aflowchart of the active material reuse method according to another embodiment of thepresent disclosure.Referring to FIG. 4, first, a discarded positive electrode scrap is prepared (step s10).As described above with reference to FIG. 1, the positive electrode scrap may be apart remained after manufacturing a positive electrode sheet including a positive electrodeactive material layer on a current collector and punching the positive electrode sheet. Inaddition, the positive electrode scrap may be prepared by collecting positive electrodes inwhich defects occur during a process. In addition, the positive electrode scrap may beprepared by separating a positive electrode from a discarded lithium secondary battery afteruse.For example, a slurry manufactured by adding and mixing N-methyl pyrrolidone(NMP) to an active material that is a lithium cobalt oxide such as LiCoO2(LCO), or an NCMbasedactive material including nickel (Ni), cobalt (Co) and manganese (Mn), carbon-basedcarbon black as a conductive material, and polyvinylidene fluoride (PVdF) that is a binderis coated on a sheet type current collector made of aluminum foil, and then, dried in a vacuumoven at about 120°C to manufacture a positive electrode sheet, and a positive electrode plateof a certain size is punched and the remaining positive electrode scrap may be prepared.Lithium composite transition metal oxides are used as the positive electrode activematerial of a lithium secondary battery, and among these, lithium cobalt oxide of LiCoO2,lithium manganese oxide (LiMnO2 or LiMn2O4, etc.), lithium iron phosphate compound(LiFePO4, etc.) or lithium nickel oxide (LiNiO2, etc.) are mainly used. In addition, as amethod of improving a low thermal stability while maintaining an excellent reversiblecapacity of LiNiO2, a nickel manganese-based lithium composite metal oxide in which a partof nickel (Ni) is substituted with manganese (Mn ) having excellent thermal stability and anNCM-based lithium composite transition metal oxide in which a part of nickel (Ni) issubstituted with manganese (Mn) and cobalt (Co) are used.As described above, the positive electrode scrap has an active material layer on acurrent collector of a metal foil such as aluminum foil. The active material layer is formedby coating a slurry in which an active material, a conductive material, a binder, a solvent,etc. are mixed, and has a structure in which the binder connects the active material and theconductive material after the solvent is volatilized. Therefore, if the binder is removed, theactive material may be separated from the current collector.Next, the positive electrode scrap is put into the heat treatment bath 120 of the activematerial recovery apparatuses 100 and 100' according to the present disclosure (step s15).The method may further include a step of crushing the positive electrode scrap to anappropriate size before step s15. Crushing refers to cutting or shredding of the positiveelectrode scrap into pieces of suitable and easy-to-handle size. After crushed, the positiveelectrode scrap is cut into small pieces, for example, 1 cm x 1 cm. For crushing, variousdry grinding equipment such as hand-mill, pin-mill, disk-mill, cutting-mill and hammer-millmay be used, or a high-speed cutter may be used. Crushing may be performed inconsideration of the characteristics, for example, fluidity, required in the active materialrecovery apparatuses 100 and 100' used in the handling of the positive electrode scrap andsubsequent processes. Since the active material recovery apparatuses 100 and 100' includethe rod 110, the positive electrode scrap may be split while the rod 110 is rotated. Therefore,if the positive electrode scrap is not too large, the positive electrode scrap is put in withoutbeing crushed.Next, the heat treatment bath 120 performs heat treatment on the positive electrodescrap in the air while rotating the positive electrode scrap around the rod 10 to remove abinder and a conductive material in the active material layer and separate the currentcollector from the active material layer (step s30). Heat treatment may be performed at 300to 650°C, which may be called high temperature heat treatment. At a temperature less than300°C, it is difficult to remove the binder, which causes a problem that the current collectormay not be separated. At a temperature equal to or greater than 650°C, the current collectormelts (Al melting point: 660°C), which causes a phenomenon that the current collector maynot be separated. Thus, a desired heat treatment temperature is obtained by adjusting thetemperature of the heating unit of the heat treatment bath 120.A heat treatment time is maintained so that the binder may be sufficiently thermallydecomposed. For example, the heat treatment time is about 30 minutes. Preferably, theheat treatment time is set to be equal to or greater than 30 minutes. The longer the heattreatment time, the longer the time for thermal decomposition of the binder to occur, butthere is no difference in the thermal decomposition effect when the heat treatment timeexceeds a certain time. Preferably, the heat treatment time is set to be equal to or greaterthan 30 minutes to 5 hours.For example, heat treatment may be performed at 550°C for 30 minutes at atemperature rise rate of 5°C / min. The temperature rise rate may be implemented withoutdifficulty, for example, through the heating unit of the heat treatment bath 120 and may beheated without generating a thermal shock, etc. to the positive electrode scrap. 550°C is toallow the thermal decomposition of the binder to occur well while considering the meltingpoint of the Al current collector. At this temperature, since heat treatment for less than 10minutes is insufficient for thermal decomposition, heat treatment should be performed formore than 10 minutes, and for more than 30 minutes if possible.As the binder and the conductive material in the active material layer are thermallydecomposed through heat treatment in the air and become CO2 and H2O and removed.Since the binder is removed, the active material is separated from the current collector, andthe active material to be recovered may be selected in powder form. Accordingly, only instep s30, the current collector may be separated from the active material layer and the activematerial in the active material layer may be recovered.It is important to perform heat treatment of step s30 in the air. If heat treatment isperformed in a reducing gas or inert gas atmosphere, the binder and the conductive materialare not thermally decomposed and only carbonized. When the binder and the conductivematerial are only carbonized, a carbon component remains on the surface of the activematerial, which degrades the performance of the reuse active material. When heattreatment is performed in the air, since a carbon material in the binder or the conductivematerial reacts with oxygen and is burned and removed as CO and CO2 gases, both the binderand the conductive material are almost removed without remaining. The active materialrecovery apparatuses 100 and 100' are suitable for performing heat treatment of step s30because a sufficient air contact is possible.The heat treatment time means a time spent at a desired heat treatment temperaturein the heat treatment bath 120. If the heat treatment time is 30 minutes, the process iscontrolled so that the positive electrode scrap may be heated in the heat treatment bath 120for 30 minutes and then transferred to the screening wall 130.Now, the active material in powder form that has passed through the screening wall130 is recovered (step s35). The active material recovery apparatuses 100 and 100' whichare open type systems may almost completely remove the binder and the conductive materialthrough the smooth air contact in the heat treatment bath 120 as described above, and recoverthe active material in powder form. Since the positive electrode scrap transferred to thescreening wall 130 is in a state in which the binder has been removed in a previous step, thecurrent collector and the active material may be completely seceded through the rotation ofthe rod 110. The carbon component generated by carbonization of the binder or conductivematerial may not remain on the surface of the active material obtained by passing throughthe screening wall 130.As described above, the use of the active material recovery apparatuses 100 and 100'ends. By performing heat treatment using the active material recovery apparatuses 100 and100', the active material may be recovered with a very high recovery rate, and since therecovered active material has no carbon component, separate treatment for removing thecarbon component is not required.If the recovered active material is reused as it is, this may lead to bad electrodeproperties. In this regard, as a subsequent process, the present disclosure proposes an activematerial reuse method that may further include steps such as cleaning, drying, addition of alithium precursor, annealing, surface coating, etc.Next, the recovered active material is cleaned and dried (step s40). Duringcleaning, it is important to clean the recovered active material with a lithium compoundaqueous solution showing basicity in an aqueous solution state. This lithium compoundaqueous solution is prepared to contain a lithium compound more than 0% and equal to orless than 15%, and preferably uses LiOH. The amount of LiOH is preferably equal to orless than 15%. The use of an excess of LiOH may leave an excess of LiOH on the surfaceof the active material even after cleaning, which may affect an annealing process in the future.In order to clean the surface of the active material in a pre-annealing step as much as possible,since an addition of the excess of LiOH is not good for the process, the addition is limited toequal to or less than 15%.Cleaning may be performed by immersing the recovered active material in such anaqueous lithium compound solution. After immersion, cleaning may be performed withinone week, preferably within one day, and more preferably within one hour. If cleaning isperformed for more than one week, there is a risk of capacity degradation due to an excessiveelution of lithium. Therefore, cleaning is preferably performed within one hour.Cleaning includes immersing the active material in the lithium compound aqueous solutionshowing basicity in the aqueous solution state, stirring the active material in an immersionstate, etc. It is good to perform stirring with immersing as much as possible. If the activematerial is only immersed in the lithium compound aqueous solution without stirring, acleaning process may be slowly performed and may cause lithium leaching. Since theprocess time may be minimized if stirring is performed with immersing, it is preferable toproceed stirring simultaneously with impregnation of the lithium compound aqueoussolution. Drying may be performed in the air in a convection type oven after filtration.The reason for cleaning with the lithium compound aqueous solution showingbasicity in the aqueous solution state is to remove LiF and metal fluoride which may bepresent on the surface of the recovered active material, and to perform surface modification.During heat treatment of step s30, the binder and the conductive material in the activematerial layer become CO2 and H2O and are vaporized and then removed. In this process,CO2 and H2O react with lithium on the surface of the active material to form Li2CO3 andLiOH, and fluorine (F) present in a binder such as PVdF reacts with a metal elementconstituting the positive electrode active material to form LiF or metal fluoride. If LiF ormetal fluoride remains, battery properties deteriorate when the active material is reused. Inthe present disclosure, reactants that may have been generated on the surface of the reuseactive material during heat treatment of step s30 are removed by adding cleaning of step s40,and thus foreign substances do not remain on the surface of the active material.Emphatically, it is important to clean the recovered active material with the lithiumcompound aqueous solution showing basicity in the aqueous solution state in step s40. Ifan aqueous solution of sulfuric acid or hydrochloric acid is used rather than the lithiumcompound aqueous solution showing basicity in the aqueous solution state, F on the surfaceof the active material may be cleaned, but the performance of the reuse positive electrodeactive material degrades by eluting transition metals (Co and Mg) present in the activematerial. The lithium compound aqueous solution showing basicity in the aqueous solutionstate used in the active material reuse method according to the present disclosure is verydesirable because the lithium compound aqueous solution may remove the binder that islikely to remain in a trace amount even after the thermal decomposition of step s30 as wellas may supplement the amount of lithium that may be eluted in the cleaning process withouteluting the transition metal, etc. present in the active material.Through step s40, in the present disclosure, it is possible to adjust the content of LiFon the surface of the recovered active material to less than 500 ppm, through which thecapacity improvement effect may be achieved. Preferably, the content of F may be set tobe equal to or less than 100 ppm. More preferably, the content of F may be set to be equalto or less than 30 ppm.Next, a lithium precursor is added to the cleaned active material and annealed (steps50).A loss of lithium in the active material intends may occur during previous steps s30and s40. In step s50, such loss of lithium is compensated.Furthermore, in step s50, the properties of the reuse active material are restored orimproved to the level of a fresh active material that has never been used by restoring a crystalstructure of the active material through annealing.Through the previous steps s30 and s40, a deformed structure may appear on thesurface of the active material. For example, in the active material which is an NCM-basedlithium composite transition metal oxide, in step s40, a spinel structure in which Ni is rocksalted [NiCO3·2Ni(OH)2)H2O] by moisture may be formed. If a battery is manufacturedas it is, battery properties such as capacity reduction may deteriorate. In the presentdisclosure, the crystal structure is restored through step s50. For example, the activematerial which is the NCM-based lithium composite transition metal oxide is restored to ahexagonal structure again. Accordingly, it is possible to restore or improve the initialproperties of the active material to a level similar to that of the fresh active material.The lithium precursor of step s50 may include at least one of LiOH, Li2CO3, LiNO3and Li2O.The lithium precursor is added by an amount that may be added as much as a ratioof lithium lost compared to a ratio of lithium to other metals in the raw material activematerial (i.e., a fresh active material) used in the active material layer before heat treatment.For example, when the ratio of lithium to other metals in the fresh active material is 1, thelithium precursor may be added by an amount of lithium that may be added at a molar ratioof 0.001 to 0.4. An amount of lithium at a molar ratio of 0.01 to 0.2 is properly added.The addition of an excess amount of lithium precursor other than the amount of lithium lostthrough cleaning, etc. causes an unreacted lithium precursor to remain in the reuse activematerial, which serves to increase resistance in an active material reuse process, and thus itis necessary to administer an appropriate amount of the lithium precursor.In addition, the lithium precursor is preferably added by an amount of lithium thatmay be further added at a molar ratio of 0.0001 to 0.1 with respect to 1:1 that is a molar ratioof lithium to other metals. The reason for adding the excess lithium as described above isto form a surface protective layer by surface coating on the active material, which will befurther described below. In the case of manufacturing a secondary battery using such anactive material, it is possible to maintain a lifespan characteristic while suppressing a sidereaction caused by an electrolyte.Annealing of step s50 may be performed at 400 to 1000°C in the air. An annealingtemperature may be 600 to 900°C. This temperature should be changed within a limitedrange depending on a type of the lithium precursor. It is preferable to set the annealingtime to be equal to or greater than one hour. Preferably, the annealing time is about 5 hours.If the annealing time is long, the crystal structure may be sufficiently recovered, but even ifthe annealing time is a long time, the performance of the active material is not significantlyaffected. The annealing time is, for example, within 15 hours.For example, when Li2CO3 is used as a lithium precursor, the annealing temperatureis preferably 700 to 900°C, more preferably 710 to 780°C. This is because the meltingpoint of Li2CO3 is 723°C. Most preferably, annealing is performed at 750°C. In the caseof using LiOH as a lithium precursor, the annealing temperature is preferably 400 to 600°C,more preferably 450 to 480°C. This is because the melting point of LiOH is 462°C.The annealing temperature is preferably a temperature exceeding the melting pointof the lithium precursor. However, at a temperature exceeding 1000°C, thermaldecomposition of the positive electrode active material occurs and the performance of theactive material deteriorates, and thus the temperature should not exceed 1000°C.When up to step s50 is performed, a reusable active material may be obtained.Reusable means that an active material is in a state in which the active material may bedirectly put into a slurry production like a fresh active material without any additionaladditives or additional treatment for adjusting components.Next, as a selective step, step s60 may be further performed. In step s60, surfacecoating is applied to the active material annealed in step s50.The surface coating step may be coating at least one of metal, organic metal and acarbon component on the surface in a solid or liquid manner and then heat treating the coatedone at 100 to 1200°C. When heat treatment is performed at a temperature exceeding1200°C, there is a risk of performance degradation due to thermal decomposition of thepositive electrode active material. In the surface coating step, coating on the surface in thesolid or liquid manner may use methods such as mixing, milling, spray drying, grinding, etc.A surface protective layer is formed by a heterogeneous metal through surfacecoating. When a molar ratio of lithium to other metals in the positive electrode activematerial is 1:1, if the lithium in the active material reacts with a surface coating material,and the molar ratio of lithium to other metals in the positive electrode active materialdecreases to less than 1:1, 100% capacity expression may not be achieved. Therefore,insufficient lithium is added in the previous step s50 so that not only the molar ratio oflithium to other metals in the positive electrode active material is 1:1 but also further anexcess of lithium is added to include more lithium by a molar ratio of 0.0001 to 0.1 comparedto other metals in the positive electrode active material. Then, during surface coating, themolar ratio of lithium to other metals in the positive electrode active material is 1:1, and thesurface protective layer may be formed.Specifically, when a metal oxide such as B, W, B-W, etc. coated on the activematerial and then heat treated, a lithium boron oxide layer may be formed on the surface ofthe active material and serves as the surface protective layer. The lithium that is moreadded at the molar ratio of 0.0001 to 0.1 in step s50 reacts with the metal oxide such as B,W, B-W, etc. in step s60, and the molar ratio of lithium to other metals in the positiveelectrode active material does not decrease to less than 1:1, and thus there is no capacitydegradation.The reusable active material obtained by the above-described method may berepresented by the following chemical formula 1.[Chemical Formula 1]LiaNixMnyCozMwO2+δ(In Chemical Formula 1 above, M includes at least one selected from the groupconsisting of B, W, Al, Ti and Mg, 1<a≤1.1, 0≤x<0.95, 0≤y<0.8, 0≤ z<1.0, 0≤w≤0.1, -0.02≤δ≤0.02, and x+y+z+w=1.)The reusable active material may have a content of F equal to or less than 100 ppm.According to the present disclosure, since it is possible to recover an active material havinga reduced content of F, if the active material having the reduced content of F is reused as anactive material, excellent resistance properties and capacity properties may be implemented.As described above, according to the present disclosure, the active material may berecovered through simple heat treatment (step s30). LiF or metal fluoride is removedduring cleaning of step s40. The cleaning and drying step using the lithium compoundaqueous solution showing basicity in the aqueous solution state has advantage of being safeand inexpensive, removing LiF or metal fluoride without loss of other elements, preventingelution of transition metals, etc. and supplementing the loss of lithium occurring during theprocess. The annealing step s50 also has advantage of being safe and inexpensive,recovering the cell properties of the reuse active material by recovering the crystal structure,that is, by improving crystallinity.The reusable active material obtained according to the present disclosure may havea particle size distribution similar to that of the fresh active material, and thus a separatetreatment for adjusting the particle size distribution may not be required. In particular,since the carbon component generated by carbonization of the binder or the conductivematerial does not remain on the surface through the active material recovery apparatuses 100and 100' suitable for heat treatment, a step for removing the carbon component, etc. is notrequired. Accordingly, the active material obtained through the method of FIG. 4 describedabove may be reused as it is without additional treatment and used to manufacture thepositive electrode.It is also possible to use 100% of the reuse active material as it is without adjustingthe composition, or mix the reuse active material with a fresh active material and mix thereuse active material with a conductive material, a binder, and a solvent to make and use aslurry.Next, FIG. 5 is a flowchart of an active material reuse method according to anotherembodiment of the present disclosure. In FIG. 5, the same reference numerals are assignedto the same steps as in FIG. 4, and repeated descriptions are omitted.Referring to FIG. 5, steps s10 to s35 described with reference to FIG. 4 areperformed in the same manner. Then, a recovered active material is cleaned (step s40').A cleaning method, a solution used for cleaning, etc. are the same as in step s40 of FIG. 4.Here, the cleaned active material is not dried but directly mixed with a lithiumprecursor solution and spray dried (step s45).Loss of lithium in the active material may occur during previous steps s30 and s40'.In step s45, such loss of lithium is more simply and definitely supplemented.As a lithium precursor solution, a lithium compound soluble in an aqueous solutionor an organic solvent may be used. In particular, the lithium precursor of step s45 maypreferably include at least one of LiOH, Li2CO3, LiNO3 and Li2O.The temperature of the spray drying step may be preferably equal to or more than100°C. When the temperature is equal to or less than 80°C, a problem in which thesolution is not completely dried may occur. More preferably, temperature of the spraydrying step may be 100 to 300°C.If the active material is dried in an oven, etc. immediately after a surfacemodification process by cleaning in step s40', active material particles may agglomerate toform a lump. To mix the lithium precursor with these agglomerated particles, grinding onthe lump may be necessary, and to mix a solid lithium precursor, a powder mixing or millingprocess is required upon mixing of materials. In that case, the process is complicated anda continuous process is difficult. In addition, in the case of an NCM-based positiveelectrode active material, when powder mixing, milling, etc. are performed on the positiveelectrode active material and the lithium precursor in the presence of moisture, the positiveelectrode active material eats the moisture so that an agglomeration phenomenon occursseverely. Therefore, the present embodiment proposes mixing and dispersing the activematerial in the lithium precursor solution without drying after cleaning in step s40', and spraydrying the active material. Then, particle agglomeration due to drying and inconvenienceof mixing the solid lithium precursor may be eliminated. That is, there may be anadvantage in that the active material is produced in powder form rather than a lump by spraydrying.During spray drying, as the lithium precursor solution is dried immediately afterspraying, the lithium precursor component is coated or contacted on the surface of the activematerial. In this regard, there is also an advantage in that particles are agglomerated by acapillary force when drying the lithium precursor solution which is a solvent, and theparticles are adjusted. In the case of a positive electrode scrap made of an electrode, theparticles on the surface may be pressed and cracked or broken by the rolling process. Inparticular, compared to LCO, the NCM-based active material has high particle splitting dueto rolling during formation of the electrode. Compared to a fresh active material, since therecovered active material includes many small particles, there is a problem of non-uniformityin the particles.In particular, the NCM-based active material including large particles that aresecondarily granulated by gathering primary particles having a size of several tens tohundreds of nm is used. In a process of rolling a positive electrode made of such an activematerial so as to adjust the porosity in the electrode, secondary particles are split to beprimarily granulated or smaller particles that have larger sizes than that of the secondaryparticles but are smaller than large particles. Since the specific surface area of the activematerial increases as the number of particles broken by rolling increases, in the case of areuse active material obtained from the rolled electrode, there may be problems that mayaffect slurry properties, electrode adhesion, and electrode performance when reused.In order for the active material to be at a reusable level, it is desirable that the particlesize distribution should not be different from that of the fresh active material. Since spraydrying may recover large particles by aggregating small particles that are split during rolling,spray drying may solve the non-uniformity in the particles and also make a particle size closeto the initial characteristics of the fresh active material. In particular, the effect is excellentin the NCM-based active material which has severe particle breakage during the rolling ofthe previous process. Therefore, it is expected that properties of a battery reusing the activematerial recovered using the method according to the present disclosure will be similar toproperties of a battery using the fresh active material.As described above, through the spray drying step (s45), the lithium precursor iscoated on the surface of the active material, and the active material is obtained by adjustingthe particles. Since the addition of the lithium precursor, granulation, and drying areperformed in one step, there is an effect of simplifying the process. In addition, spraydrying is special in that it is not means for simply obtaining the active material, but meansfor again granulating particles that have been previously used and broken by rolling, etc.In addition, if the active material particles cleaned in step s40' is merely mixed anddispersed in the lithium precursor solution of a certain concentration, step s45 proceeds, andthus there is an advantage that a continuous process is possible for cleaning in step s40' andspray drying in step s45. As such, in the active material reuse method according to thepresent embodiment, there is a continuity of the process, and there is an advantage in thatcoating of the lithium precursor, drying, and granulation (particle readjustment) areperformed simultaneously in one step.Here, the lithium precursor is also added by the amount as much as added in steps50 described with reference to FIG. 4 that is an amount that may be added as much as aratio of lithium lost compared to a ratio of lithium to other metals in the fresh active material.Next, the active material that is spray dried is annealed (step s50'). Since thelithium precursor is added to the active material in step s45, in this step, annealing may beperformed immediately after spray drying without adding an additional lithium precursor.An annealing effect of step s50' is the same as that of step s50 described with reference toFIG. 4. Thereafter, if necessary, surface coating of step s60 may be further performed.Meanwhile, another positive active material reuse method using the active materialrecovery apparatuses 100 and 100' is also possible. For example, the heat treatment timeof step s30 described with reference to FIG. 3 may be set within one hour, preferably within30 minutes. The longer the heat treatment time, the longer the time for thermaldecomposition of the binder to occur, but there is no difference in the thermal decompositioneffect when the heat treatment time exceeds a certain time, and on the contrary, it is not goodsince many reaction products such as LiF which are harmful to the battery performance aregenerated. Therefore, a method capable of minimizing the generation of unwanted foreignsubstances that may adversely affect the battery performance by limiting the heat treatmenttime to within one hour, preferably 30 minutes is possible.In this case, steps s50 and s60 may be performed immediately after step s30 and steps35 of FIG. 3 without step s40. That is, as a result of shortening heat treatment, the cleaningstep may be omitted. As described above, according to another embodiment of the presentdisclosure, a reusable active material may be obtained with only two steps of heat treatmentin the air (step s30) and annealing after addition of the lithium precursor (step s50). Inparticular, since heat treatment is performed for a very short time, preferably within 30minutes, there is an advantage in that an additional step such as washing for removing thereaction products that adversely affect the battery properties is not required by suppressingthe reaction products.Meanwhile, another positive active material reuse method using the active materialrecovery apparatuses 100 and 100' is also possible. For example, the cleaning time of steps40 described with reference to FIG. 4 is shortened within one hour, preferably within 10minutes. If cleaning is performed for a long time, there is a risk of capacity degradationdue to an excessive elution of lithium. Thus, a method capable of minimizing the elutionof lithium by limiting the cleaning time and shortening cleaning.In this case, only the lithium precursor aqueous solution used as a cleaning liquid instep s40 is sufficient to supplement loss of lithium. Therefore, annealing may be performedwithout adding an additional lithium precursor to the cleaned active material. That is, ifthe cleaning time of step s40 in FIG. 4 is set to be very short, annealing may be performedimmediately as in step s50' of FIG. 5.As described above, according to the present disclosure, various methods ofobtaining a reusable positive electrode active material are possible, and may be performedmore efficiently by using the active material recovery apparatus of the present disclosureoptimized for separation of the current collector and the active material layer.Hereinafter, experimental examples of the present disclosure will be described indetail.<Experimental Example 1>Samples 1 and 2 were set using methods below, positive electrode scraps were heattreated by the respective methods, and then an active material recovery rate was evaluated.Sample 1:The positive electrode scraps were simply stacked in a furnace and then heat treated.This is a case where the positive electrode scraps are placed as a fixed type in the furnace.FIG. 6 is a picture showing a difference in heat treatment results according to alocation of the positive electrode scrap in Sample 1.FIG. 6(a) is a picture of the positive electrode scrap located on the surface amongthe stacked positive electrode scraps. In the case of this positive electrode scrap, it wasobserved that the active material was separated from a current collector as a binder and aconductive material were thermally decomposed by a contact with air due to an exposure tothe outside, but a place where less thermal decomposition occurs, that is, an active materiallayer was not separated from the current collector due to an incomplete combustion in whichsufficient air and oxygen were not supplied rather was strongly carbonized and attached tothe current collector was also observed.FIG. 6(b) is a picture of the positive electrode scrap located inside among the stackedpositive electrode scraps. In the case of this positive electrode scrap, it is evaluated that acontact with air was insufficient because the positive electrode scrap was in contact withdifferent positive electrode scraps at the top and bottom. Quite many places where lessthermal decomposition occurs and the active material layer is carbonized and attached to thecurrent collector were observed.As such, it was confirmed that, when the positive electrode scraps were stacked instack form and heat treated as the fixed type, since the active material is not separated fromthe current collector due to the incomplete combustion, the recovery rate was very poor. Aresult that when 100 g of positive electrode scraps is heat treated, about 40 g of positiveelectrode scraps is not recovered was obtained.Sample 2:The positive electrode scraps were erected in the furnace to have more air contactthan Sample 1, and then heat treated. This is a case where the positive electrode scraps areplaced as the fixed type in the furnace, but distances between the positive electrode scrapsare secured to maximize the surface in contact with air.FIG. 7 is a picture showing a state of Sample 2 by time according to an experimentalprocess.FIG. 7(a) is a picture showing a state of shredded positive electrode scraps that arestacked upright in a crucible. FIG. 7(b) is a picture showing a state of the positive electrodescraps that are put in a furnace and heat treated at 550°C in the air for 30 minutes. FIG.7(c) is a picture showing the positive electrode scraps that were heat treated are taken outfrom the crucible. FIG. 7(d) is a picture showing a state of an active material in powderform that is recovered from the surface of the positive electrode scraps.In Sample 2, unlike Sample 1, a result that most of the active material is secededand recovered from a current collector was obtained. The recovery rate was equal to ormore than 95%. Through this, it was confirmed that a meaningful amount of the activematerial may be recovered only by heat treatment in the air without using acid or NMP. Inparticular, the active material recovery apparatus of the present disclosure was inventedbased on that if a contact area with air may be further increased, since even a part (5%) ofthe active material remaining in the current collector may be seceded, the recovery rate ofthe active material may be further increased. Compared to Comparative Example 2, theactive material recovery apparatus of the present disclosure is a portable type that rotates thepositive electrode scrap and has the recovery rate much higher than 95% since the contactwith air is smoother.<Experimental Example 2>Each positive electrode active material was prepared using methods as inEmbodiments and Comparative Examples below, and electrochemical performance thereofwas evaluated.Embodiment 1:A reuse active material was collected according to the active material reuse methodof the present disclosure as described above with reference to FIG. 4. A positive electrodescrap to be discarded after punching a positive electrode plate having an NCM-based lithiumcomposite transition metal oxide active material was prepared and heat treatment of step s30was performed at 500°C for 30 minutes. Cleaning of step s40 was performed for 10minutes using LiOH. In step s50, with respect to the molar ratio of lithium to other metalsin the raw material active material (ICP analysis), a lithium precursor (Li2CO3) of an amountby which lithium may be further add at a molar ratio of 0.09 during the process wasadministered and annealed at 750°C for 15 hours. Theoretically, in the case of a freshactive material, the molar ratio of lithium to other metals is 1:1, but since an average errorof an ICP active material recovery apparatus which is an active material recovery apparatusthat checks the molar ratio is ±0.05, preferably about ±0.02, the molar ratio of lithium toother metals of the raw material active material through ICP measurement may be 1±0.05:1.In the present experiment, the lithium precursor was added with respect to the analysis ratiothrough the ICP analysis.Embodiment 2:In addition to Embodiment 1, an active material surface protective layer recoveryprocess of optional step s60 of FIG. 4 was also performed.Comparative Example 1:A fresh NCM-based lithium composite transition metal oxide was used, other thana reuse active material.Comparative Example 2:In the active material reuse method of the present disclosure as described above,only heat treatment of step s30 is performed to remove the binder and the conductive material,separate the Al current collector, and collect the NCM-based lithium composite transitionmetal oxide active material. Step s30 was performed under the same conditions as inEmbodiment 1. In the active material reuse method of the present disclosure, surfacemodification of step s40, crystal structure recovery of step s50, and a surface coating processof step s60 were not performed.Comparative Example 3:Further to Comparative Example 2, in the active material reuse method of thepresent disclosure as described above, up to surface modification of step s40 was performedto collect the active material. That is, while surface modification was performed, in theactive material reuse method of the present disclosure as described above, crystal structurerecovery of step s50 and the surface coating process of step s60 were not performed. Steps40 was performed under the same conditions as in Embodiment 1.Comparative Example 4:Further to Comparative Example 2, in the active material reuse method of thepresent disclosure as described above, surface modification of step s40 was not performedand only up to crystal structure recovery of step s50 was performed to collect the NCMbasedlithium composite transition metal oxide active material. Annealing for crystalstructure recovery was performed without adding the lithium precursor unlike inEmbodiment 1.Comparative Example 5:In the same manner as Embodiment 1, only up to steps s30, s40, and s50 wereperformed. However, annealing for crystal structure recovery was performed withoutadding the lithium precursor unlike in Embodiment 1.ICP analysis was performed on the positive active materials recovered from orprepared in the Embodiment and Comparative Examples, and a remaining amount of LiF, aratio of lithium and other metals in the active material, and an amount of a specific elementsuch as B or W were also analyzed.The positive electrode was manufactured from a slurry prepared by weighing 96.25wt% of the positive active material recovered from or prepared in each of Embodiments 1and 2 and Comparative Examples 1 to 5 above, 1.5 wt% of carbon black that is a conductivematerial, and 2.25 wt% of PVdF that is a binder and mixing them with NMP, then the cell(Coin Half Cell, CHC) was manufactured, and electrochemical performance thereof wasevaluated.To know the amount of LiF remaining in the active material recovered inComparative Examples 2 and 3, F was detected and analyzed by ICP. The results areshown in Table 1 below.[Table 1]ND means that the content of F equal to or less than 30 ppm is measured. Referringto Table 1 above, it may be seen that the content of F in the recovered positive active materialwas significantly reduced in Comparative Example 3 as compared to Comparative Example2. That is, it may be confirmed that LiF is completely dissolved in a lithium compoundaqueous solution by cleaning and removed to the extent that LiF may not be detected by ICP.Therefore, it may be seen that removal of LiF is excellent by step s40.To see if there is a change in a lithium component in the positive active materialduring steps s30 and s40 of the present disclosure, the ratio of lithium to other metals in theactive material was analyzed by ICP. The results are shown in Table 2 below.[Table 2]Referring to Table 2, it may be seen that the ratio of lithium to other metals in theactive material decreases about 0.2 to 0.5 in Comparative Example 2 compared toComparative Example 1 through heat treatment of s30, and about 0.2 to 0.5 in ComparativeExample 3 compared to Comparative Example 2 through cleaning and drying of s40. TheNCM-based lithium composite transition metal oxide appears to have a relatively largeparticle specific surface area and a great decrease in the ratio of lithium to other metals dueto a change to a spinel structure. Therefore, it may be seen that insufficient lithium mustbe supplemented.Table 2 shows the values measured by the ICP analysis, and as mentioned above,the ICP analysis has an error value of about ±0.02. Therefore, even in ComparativeExample 1 which is the fresh active material, the ratio between lithium to other metals maybe less than 1. Therefore, an amount of lithium precursor added to supplement loss oflithium is added by the content of lithium as much as decreased with respect to the ratio oflithium and other metals (a molar ratio analyzed by ICP) in a raw material active material(i.e., the fresh active material) used in the active material layer.FIGS. 8 and 9 show results of cell evaluation using the active materials ofEmbodiments 1 and 2 and Comparative Examples 1 to 5. The rate performance wasreviewed by evaluating the capacity according to the number of cycle repetitions at differentcurrents. The active material recovery apparatus used for evaluation is a generalcharging / discharging test apparatus that is well used in the laboratory. There is nodeviation according to a measuring apparatus or method. In the graphs of FIGS. 8 and 9,the horizontal axis indicates the number of cycles and the vertical axis indicates the capacity.The voltage was set to 3 to 4.3V, and initial formation charging / discharging wasperformed at 0.1C / 0.1C. An electrolyte constituting the cell that is carbonate-based, has3:7 of ethylene carbonate (EC) to ethyl methyl carbonate (EMC), and partially includes anadditive was used.First, referring to FIG. 8, after primary heat treatment (550°C / 30 minutes) forsecession, upon reviewing Comparative Example 2 before surface modification andComparative Example 3 after surface modification, the electrode capacity rapidly decreasesin Comparative Example 3 in which surface modification was performed. This is because,as mentioned above, Ni in the NCM-based lithium composite transition metal oxide wasrock salted by moisture, and the capacity thereof decreased.However, when annealing (750°C / 15 hours) is performed without surfacemodification, this corresponds to Comparative Example 4 which has almost no capacityimprovement effect compared to Comparative Example 2. This is because of LiFremaining on the surface of the active material when surface modification is not performed.This has been shown in Table 1 above that LiF is removed to a satisfactory level only whencleaning is performed.When surface modification and annealing are performed after primary heattreatment, the capacity is increased as shown in Comparative Example 5. This is because,although the capacity is decreased as in Comparative Example 3 after the surfacemodification step, Ni rock salt decreases through annealing after LiF is removed by surfacemodification and the structure is restored to a hexagonal crystal.Next, referring to FIG. 9, the capacity improvement of Embodiment 1 compared toComparative Example 5 is confirmed. In Embodiment 1, a lithium precursor was addedduring annealing compared to Comparative Example 5. By adding the lithium precursoras such, it may be seen that the capacity is improved by supplementing the lithium lost inthe previous steps. The loss of lithium occurred through heat treatment and cleaning hasbeen described with reference to Table 2.Based on the results of ICP analysis (Table 2), the lithium compound was added asmuch as a ratio of loss compared to the content of lithium in the existing positive electrodeactive material. As a result, it was confirmed through an additional experiment that whena molar ratio of 0.09 to 0.1 is added, the capacity improvement effect equivalent to that ofComparative Example 1 is obtained.As described above, according to the present disclosure, the active material may berecovered from the positive electrode scrap so as to be directly reused. It is safe because atoxic and explosive solvent such as NMP, DMC, acetone, and methanol is not used, and itis suitable for mass production because simple and safe methods such as heat treatment,cleaning and drying, and annealing are used.FIGS. 10 and 11 are scanning electron microscope (SEM) pictures of the activematerials of Embodiment 1 and Comparative Examples 1 to 3 and 5. The SEM pictureswere taken with a general SEM apparatus that is well used in the laboratory. For example,the SEM pictures may be taken using s-4200 of HITACHI. However, there is no deviationaccording to a measuring apparatus or method.FIG. 10(a) is a SEM picture of a fresh active material of Comparative Example 1,and FIG. 10(b) is an enlarged picture of FIG. 10(a). FIG. 10(c) is a picture of a surface ofa positive electrode scrap manufactured with such a fresh active material, and FIG. 10(d) isan enlarged picture of FIG. 10(c). The fresh active material has no particle breakage, butthe positive electrode scrap made of an electrode shows that particles on the surface arepressed and broken by a rolling process.FIG. 10(e) is an SEM picture of Comparative Example 2, and FIG. 10(f) is anenlarged picture of FIG. 10(e). With reference to FIGS. 10(e) and 10(f), no binder orconductive material is observed in the recovered active material. That is, it may beconfirmed that a binder or a conductive material are removed during a high temperature heattreatment process. Therefore, it may be seen that the active material is separated from acurrent collector only by heat treatment in the air, and the binder or the conductive materialdoes not almost remain on the surface of the active material.FIG. 11(a) is an SEM picture of Comparative Example 3, and FIG. 11(b) is anenlarged picture of FIG. 11(a). Upon comparing FIGS. 11(c) and 11(d) which are picturesof the positive electrode scrap, it may be seen that particles are released through the process.FIG. 11(c) is an SEM picture of Comparative Example 5, and FIG. 11(d) is anenlarged picture of FIG. 11(c). FIG. 11(e) is an SEM picture of Embodiment 1, and FIG.11(f) is an enlarged picture of FIG. 11(e). It may be seen that the particles released in theprevious step are aggregated through annealing. Upon comparing FIG. 11(f) with FIG.10(a), it may be seen that the reuse active material of Embodiment 1 has the same shape asthat of the fresh active material.ICP analysis was performed on the positive active materials recovered from orprepared in the Embodiment and Comparative Examples, and an amount of a specificelement was also analyzed. The results are shown in Table 3 below.[Table 3]As shown in Comparative Example 1, the fresh active material used in the presentexperiment further includes B and W. Comparative Example 2 shows that content of Band W is reduced through heat treatment, and it may be seen from the remaining results thatalmost B is almost removed in subsequent processes. In the case of W, it may be seen thata large amount of W is removed during the surface modification process through cleaningas in Comparative Example 3.Therefore, since according to a type of an initially used active material, a specificelement may be lost during the process, and in particular, the specific element may becompletely removed or a small amount thereof remains during the surface modificationprocess through cleaning, there may be a case in which it is difficult to fully recovercharacteristics by performing only up to the annealing step as in Embodiment 1. In such acase, it is preferable to perform an additional surface coating step as proposed in the presentdisclosure. The surface coating step is to coat B and W in the case of the presentexperimental example. Surface coating may act as a surface protective layer of the positiveelectrode active material. Surface coating may also be a process that supplements a specificinsufficient element and at the same time, rebuilds the surface protective layer in the freshactive material. In the case of the fresh active material used in the present experiment, thesurface protective layer is made of B-W, and the meaning of loss of lithium during theprocess is interpreted as a ratio of (lithium of the active material itself + lithium forming thesurface protective layer) to other metals, other than the 1:1 ratio of lithium in the activematerial itself to other metals. Therefore, the molar ratio of 0.09 lost in the aboveexperiment as in Comparative Example 3 may be interpreted as an amount of lithium inwhich lithium in the positive active material and lithium for forming the surface protectivelayer are summed, and the lithium precursor capable of supplementing the amount of lithiumas much is added in the embodiments.The surface coating step entails the heat treatment process after the solid or liquidreaction. When the reusable active material is represented by chemical formula 1mentioned above, it may be considered that M in Chemical Formula 1 is supplementedthrough this surface coating.When the surface coating layer includes B, B-W, B-Ti, and B-W-Ti, surface coatingheat treatment may be performed at a temperature of 200 to 500°C, and other componentsmay be also coated with a metal component, a carbon component and organic metalcomponents at a temperature within 100 to 1200°C.As described above, according to the present disclosure, the positive electrode scrapmay be reused using a simple, eco-friendly, and economical method, and even if a lithiumsecondary battery is manufactured by reusing the NCM-based lithium composite transitionmetal oxide positive electrode active material prepared as described above, there is noproblem in the performance of the battery.<Experimental Example 3>Each positive electrode active material was prepared using methods as inEmbodiments and Comparative Examples below, and electrochemical performance thereofwas evaluated.Embodiment 3:Embodiment 3 is the same as Embodiment 1, except that the annealing time was 5hours shorter than 15 hours in Embodiment 1.Embodiment 4:Embodiment 4 is the reused active material prepared according to the methoddescribed with reference to FIG. 5. After up to step s30 as in Embodiment 1 was performed,steps s40', s45 and s50' were performed. Without drying after cleaning in step s40', (awashing electrode) was mixed with LiOH powder of 0.1 mol in an aqueous solution (mixedat a ratio of 1: 50 of powder to aqueous solution) and granulated with spray drying equipmentto perform step s45. Step s50' was performed at 750°C for 5 hours as in Embodiment 3.Upon performing step s45, the mixing aqueous solution of the washing electrodeand LiOH of 0.1 mol were stirred to prevent electrode precipitation, and adjusted anatmospheric temperature (input temperature) when the spray drying equipment sprays to aheating container using a spray nozzle to be 180°C and an atmospheric temperature (outputtemperature) when coming out from the heating container to a collection container tomaintain 100°C or more.FIG. 12 is a particle size distribution graph of the active materials of Embodiments3 and 4 and Comparative Examples 1 and 2. The particle size distribution may be obtainedby a general particle size analyzer well used in the laboratory. For example, the particle sizedistribution may be measured using a Horiba LA 950V2 particle size analyzer. However,there is no deviation according to a measuring apparatus or method. In FIG. 12, thehorizontal axis represents particle size (μm) and the vertical axis represents volume %.In the case of Comparative Example 2, the active materials of Comparative Example1 were split into particles of sub-micron size (less than 1 micrometer) and micronized bypressure in the electrode process. As such, Comparative Example 2 has a very differentparticle size distribution from that of Comparative Example 1.Since in Embodiment 3 and Embodiment 4, up to annealing was performed, duringannealing, the previously added lithium precursor melted and agglomeration of particles wasinduced, and thus it may be seen that many of the micronized particles shown in ComparativeExample 2 disappeared. In particular, in the case of Embodiment 4 according to the presentdisclosure, compared to Embodiment 3, small particles decrease and large particles slightlyincrease, but there is no significant difference in the particle size distribution. Embodiment4 may be regarded to be more similar to the particle size distribution of ComparativeExample 1 compared to Example 3 from the fact that small-sized particles are fewer.As such, it was confirmed that upon using spray drying proposed in anotherembodiment of the present disclosure (Embodiment 4), the particle size distribution is moresimilar to that of the fresh active material (Comparative Example 1) compared to the case ofmixing the lithium precursor in a solid phase (Embodiment 3), and in particular, there is anadvantage that a continuous process with the cleaning step before spray drying is possible.FIG. 13 shows results of cell evaluation using the active materials of Embodiments3 and 4 and Comparative Example 1, and resultant values are summarized in Table 4.[Table 4]Referring to FIG. 13 and Table 4, both the electrodes using Embodiment 3 andEmbodiment 4 showed similar results to the electrode using Comparative Example 1. Theinitial formation capacity is high in Comparative Example 1 and the c-rate capacity is slightlyhigher in Embodiment 3 and Embodiment 4, but it is determined that they are similar to eachother. As described above, according to the embodiments of the present disclosure, thereuse active material similar to the fresh active material (Comparative Example 1) may beobtained.<Experimental Example 4>Each positive electrode active material was further prepared using methods as inEmbodiments and Comparative Examples below, and electrochemical performance thereofwas evaluated.Embodiment 5:A reuse active material was collected according to another active material reusemethod of the present disclosure as described above. An LCO positive electrode scrap tobe discarded after punching a positive electrode plate was prepared and heat treatment ofstep s30 was performed at 600°C in the air for 30 minutes at a temperature rise rate of5°C / min. Step s50 was performed without cleaning of step s40 or s40'. The lithiumprecursor (Li2CO3) of an excess amount of 2 mol% of lithium compared to an amount oflithium of the reuse LCO was put in and annealed at 750°C in the air for 15 hours.Comparative Example 6: The fresh LCO was used other than the reuse activematerial.Comparative Example 7: In the active material reuse method of the presentdisclosure as described above, only heat treatment of step s30 was performed to remove thebinder, the conductive material, and the Al current collector, and the LCO active materialwas collected. Step s30 was performed under the same conditions as in Embodiment 5.Comparative Example 8: The LCO active material was collected in the same manneras in Comparative Example 7, except that the heat treatment time was 1 hour.Comparative Example 9: The LCO active material was collected in the same manneras in Comparative Example 8, except that the heat treatment time was 5 hours.FIG. 14 shows results of cell evaluation using the active materials of Embodiment5 and Comparative Examples 6 to 9.Referring to FIG. 14, the lowest rate performance may be confirmed in ComparativeExample 9 in which the heat treatment time is the longest as 5 hours. This is because, whenthe high temperature heat treatment process such as step s30 is performed for a long time,the binder and the conductive material are removed as CO2 and H2O, react with lithium onthe surface of the positive electrode active material to form Li2CO3, react with F present inthe binder to form LiF. Furthermore, it is determined to exhibit low battery properties dueto Co3O4 generated on the LCO surface by thermal decomposition.In Comparative Example 8, it may be seen that since the heat treatment time was 1hour which is shorter than Comparative Example 9, the rate performance was better thanthat of Comparative Example 9 until about the initial cycle 3, but as the number of cyclesincreased, the rate performance deteriorated.In Comparative Example 7, the heat treatment time was 30 minutes which is shorterthan Comparative Examples 8 and 9. In the case of Comparative Example 7, the rateperformance is superior to those of Comparative Examples 8 and 9. Therefore, it may beconfirmed that the heat treatment time is preferably within 30 minutes in terms of the rateperformance because the generation of reaction products such as LiF is minimized.In Embodiment 5, compared to Comparative Example 7, up to annealing wasperformed by adding the lithium precursor, during which Li2CO3 was added to supplementlithium lost in the process of recovering the active material and to restore crystallinity.According to Embodiment 5, it is possible not only to supplement an insufficient amount oflithium occurred during the process, but also to reduce a deformed structure and Co3O4 thatmay appear on the surface of the active material during regeneration to the LCO crystalstructure again, and thus it is confirmed that Embodiment 5 exhibits results improvedcompared to the initial characteristics of the fresh LCO active material of ComparativeExample 6. As described above, according to the present disclosure, the active materialmay be recovered from the positive electrode scrap so as to be directly reused.FIG. 15 shows XRD patterns of active materials of Embodiment 5 and ComparativeExamples 6, 7, and 9. In the XRD pattern, the horizontal axis represents 2θ (Theta)(degrees), and the vertical axis represents intensity. The XRD pattern has been obtainedusing a general X-ray diffraction apparatus that is well used in the laboratory. For example,the XRD pattern may be analyzed using an X-ray diffractometer XG-2100 manufactured byRigaku. However, there is no deviation according to an apparatus or the method.FIG. 15(a) is an XRD pattern of Comparative Example 6, that is, the XRD patternof fresh LCO. FIG. 15(b) is an XRD pattern of the active material of Comparative Example7, and FIG. 15(c) is an XRD pattern of the active material of Comparative Example 9.Upon comparing FIGS. 15(b) and 15(c) with FIG. 15(a), the Co3O4 phase is checked. Thatis, it may be confirmed that Co3O4 is generated on the surface of LCO during heat treatmentof step s30.FIG. 15(d) is an XRD pattern of the active material of Embodiment 5. Uponcomparing FIGS. 15(b) and 15(c) with FIG. 15(d), it may be seen that the Co3O4 phasedisappears and the crystal structure is restored to LCO through annealing of step s50. Inview of the location of a diffraction peak in the XRD pattern, the crystal structure of FIG.15(d) is similar to the crystal structure of FIG. 15(a). Therefore, it may be confirmed thatthe embodiment of the present disclosure is restored to the level of the fresh active materialof Comparative Example 6. As described above, according to the present disclosure,Co3O4 generated during the heat treatment process may be removed during the annealingprocess, and the active material may be recovered from the positive electrode scrap so as tobe directly reused.FIG. 16 is SEM pictures of the active materials of Embodiment 5 and ComparativeExample 6.FIG. 16(a) is a SEM picture of the fresh LCO of Comparative Example 6, and FIG.16(b) is a SEM picture of the reuse active material of Example 5. It may be confirmed thatthe recovered LCO of Embodiment 5 also exhibits the same shape as compared with thefresh LCO. Furthermore, since only LCO is observed, it is confirmed that the binder andthe conductive material were removed during the high temperature heat treatment process.Therefore, it may be seen that the active material is separated from the current collector onlyby heat treatment in the air, and almost no binder or conductive material remains on thesurface of the active material. As described above, according to the present disclosure, itis possible to separate the active material from the current collector without using acomplicated method or harmful substances, and thus the active material may be recoveredin an eco-friendly manner. The active material may be reused without using an acid, andthus a neutralization process or a wastewater treatment process is not required, therebyrelaxing environmental issues and reducing process costs.FIG. 17 shows X-Ray Photoelectron Spectroscopy (XPS) patterns of activematerials of Comparative Examples 6, 7, and 9. In the XPS patterns, the horizontal axisrepresents the binding energy (unit: eV). The XPS patterns may be obtained using ageneral XPS measuring apparatus that is well used in the laboratory. For example, the XPSpatterns may be analyzed using K-Alpha from Thermo Fisher Scientific. As mentionedabove, F present in the binder may react with Li of the active material during the heattreatment process to form LiF.In FIG. 17, a peak near 684 eV appears by LiF, and the higher the intensity accordingto the sample, the greater the amount of LiF is present on the surface of the positive electrodeactive material. Since the XPS pattern of Comparative Example 6 was measured usingfresh LCO, the presence of LiF was not measured. In Comparative Example 9, a greatamount of LiF was generated on the surface of the active material due to heat treatment fora long time of 5 hours. As a result, the LiF peak intensity of XPS was measured to besignificantly higher than that of Comparative Example 6. However, in the case ofComparative Example 7 in which the heat treatment time is reduced from 5 hours to 30minutes, it may be seen that the formation of F due to binder decomposition is relativelyreduced, and the amount of LiF present on the surface of the active material is relativelyreduced. LiF should be as small as possible because it may cause deterioration of electrodeproperties. From the results of Comparative Example 9 and Comparative Example 7, itmay be seen that a decrease in the heat treatment time may reduce the amount of LiF on thesurface of the regenerated active material and is effective in improving the performance ofthe regenerated active material. Embodiment 5 will have LiF of a level similar to that ofComparative Example 7, but as shown in the results of FIG. 14 above, LiF of a level higherthan that of the fresh active material may be secured after annealing, and thus it may be seenthat the amount of LiF remaining in Embodiment 5 is not so much a problem for batteryperformance. Therefore, if the heat treatment time is optimized as in another embodimentof the present disclosure, a separate process such as washing for removing LiF, etc. is notrequired.FIG. 18 is a particle size distribution graph of the active materials of Embodiment 5and Comparative Examples 6, 7, and 9. All the active materials recovered in Embodiment5 and Comparative Examples 6, 7, and 9 have a similar particle size distribution comparedto the fresh LCO of Comparative Example 6. It is defined that when the volume % ofparticles having the same particle size differs only in the range within ±2%, the particle sizedistribution is similar. As described above, according to the present disclosure, since theparticle size distribution of the active material does not differ, the initial characteristics arealmost maintained, and it is expected that properties of a battery reusing the active materialwill be similar to properties of a battery using the fresh active material.<Experimental Example 5>Each positive electrode active material was prepared using methods as inEmbodiment and Comparative Examples below, and electrochemical performance thereofwas evaluated.Embodiment 6: A reuse active material was collected according to another activematerial reuse method of the present disclosure as described above. A positive electrodescrap to be discarded after punching a positive electrode plate was prepared and heattreatment of step s30 was performed at 600°C for 30 minutes. Cleaning of step s40 wasperformed for 10 minutes using LiOH. Annealing was performed at 750°C for 15 hourswithout adding an additional lithium precursor as in step s50'.Comparative Example 10: In addition to Comparative Example 7, an LCO activematerial was recovered by performing surface modification of step s40 in the active materialreuse method of the present disclosure as described above. That is, crystal structurerecovery of step s50 or s50' was not performed in the active material reuse method of thepresent disclosure while performing surface modification. Step s40 was performed underthe same conditions as in Embodiment 6.To know an amount of LiF remaining in the active material recovered inEmbodiment 6 and Comparative Example 7, F was detected and analyzed by ICP. Theresults are shown in Table 5 below.[Table 5]Referring to Table 5 above, it may be seen that the content of F in the recoveredpositive active material was significantly reduced in Embodiment 6 as compared toComparative Example 7. That is, it may be confirmed that LiF is completely dissolved ina lithium compound aqueous solution by cleaning and removed to the extent that LiF maynot be detected by ICP. Therefore, it may be seen that removal of LiF is excellent by steps40.ICP analysis was performed on the positive active materials recovered from orprepared in the Embodiment and Comparative Examples, and an amount of a specificelement was also analyzed. The results are shown in Table 6 below.[Table 6]As shown in Comparative Example 6, the fresh active material used in the presentexperiment further includes Al. Comparative Example 7 shows that the content of Al isnot changed even through heat treatment, and it may be seen from the content of Al ismaintained even Comparative Example 10 and Embodiment 6 that further includesubsequent processes. As described above, according to the present disclosure, it may beseen that LiF or metal fluoride without may be removed without loss of other elements suchas Al, and elution of transition metals, etc. may be prevented.FIG. 19 shows results of cell evaluation using active materials of Embodiment 6 andComparative Examples 6, 7, and 10.Referring to FIG. 19, the lowest rate performance may be confirmed in ComparativeExample 7 in which surface modification and crystal structure recovery according to thepresent disclosure were not performed in spite of the reuse active material. This is because,during the high temperature heat treatment process such as step s30, not only the binder andthe conductive material are removed as CO2 and H2O and react with lithium on the surfaceof the positive electrode active material to form Li2CO3 and LiOH but also react with Fpresent in the binder to form LiF or metal fluoride on the surface of the reuse active material.Furthermore, it is determined to exhibit low battery properties due to Co3O4 generated onthe LCO surface by thermal decomposition.In Comparative Example 10, surface modification was performed compared toComparative Example 7. Comparative Example 10 is evaluated to have been able to obtainbetter results than Comparative Example 7 because reactants generated on the surface wereremoved through cleaning.In Embodiment 6, compared to Comparative Example 10, up to annealing wasperformed. A deformed structure and Co3O4 that may appear on the surface of the activematerial during regeneration are reduced to the LCO crystal structure again, and thus it isconfirmed that Embodiment 6 exhibits results improved compared to the initialcharacteristics of the fresh LCO active material of Comparative Example 6. As describedabove, according to the present disclosure, the active material may be recovered from thepositive electrode scrap so as to be directly reused.FIG. 20 shows XPS patterns of the active materials of Embodiment 6 andComparative Examples 6 to 8. Since the XPS pattern of Comparative Example 6 wasmeasured using fresh LCO, the presence of LiF was not measured. However, inComparative Example 7, the presence of LiF formed on the surface of the active materialduring the heat treatment process may be confirmed. In Comparative Example 8, since theheat treatment time was increased to 5 hours, the generation of F was increased compared toComparative Example 7, and since the amount of LiF generated on the surface of the activematerial was increased, the LiF peak intensity of XPS was measured higher than that ofComparative Example 7. Since the amount of LiF present on the surface of the activematerial causes deterioration of electrode properties, it is necessary to remove LiF. InEmbodiment 6, compared to Comparative Example 7, LiF was removed through cleaning,and it may be confirmed that the peak of LiF does not appear even in the XPS results.Through the XPS analysis described above, it may be confirmed that the results ofEmbodiment 6 are similar to the results of Comparative Example 6. Therefore, it may beconfirmed that Embodiment 6 of the present disclosure is restored to the level of the freshactive material of Comparative Example 6. As described above, according to the presentdisclosure, when the cleaning time is shortened, the active material may be recovered fromthe positive electrode scrap so as to be directly reused even without addition of a lithiumprecursor.The present disclosure has been described in detail. However, it should beunderstood that the detailed description and specific examples, while indicating preferredembodiments of the disclosure, are given by way of illustration only, since various changesand modifications within the scope of the disclosure will become apparent to those skilledin the art from this detailed description.

Claims

1. An active material recovery apparatus which is a rotary firing apparatus comprising a rod of a screw type therein, the active material recovery apparatus comprising: a heat treatment bath and a screening wall arranged in a line along an axis of the rod, wherein the heat treatment bath constitutes a heating zone, and the screening wall constitutes a cooling zone; and an exhaust injection and degassing system, wherein the heat treatment bath removes a binder and a conductive material in an active material layer by performing heat treatment in air on an electrode scrap comprising the active material layer on a current collector while rotating the electrode scrap around the axis of the rod, and separates the current collector from the active material layer, and an active material in the active material layer passes through the screening wall and is recovered as an active material in powder form, and the current collector that does not pass through the screening wall is recovered separately.

2. The active material recovery apparatus of claim 1, wherein the heat treatment bath also rotates around the axis of the rod.

3. The active material recovery apparatus of claim 1, wherein an angle of the entire active material recovery apparatus is adjusted so that the axis of the rod is inclined with respect to a ground.

4. The active material recovery apparatus of claim 1, wherein the active material recovery apparatus has a vibration function.

5. The active material recovery apparatus of claim 1, wherein input of a new electrode scrap and recovery of the active material are continuously performed.

6. The active material recovery apparatus of claim 1, wherein the heat treatment bath has a tubular shape with both ends open so that the electrode scrap is put therein and the separated current collector and active material are transferred to the screening wall, and a tube is an open type system through which air enters and exits.

7. The active material recovery apparatus of claim 6, wherein the screening wall has a tubular shape with both ends open so that the separated current collector and active material are put therein and the current collector is discharged.

8. The active material recovery apparatus of claim 1, wherein the heat treatment bath is an open type system in which air of 10 mL / min to 100 L / min is added or injected per 100 g of the electrode scrap that is put in.

9. The active material recovery apparatus of claim 1, wherein air inlets are formed in a plurality of places in the heat treatment bath.

10. A positive electrode active material reuse method comprising: preparing an active material recovery apparatus according to any one of claims 1 to 9; putting a positive electrode scrap in a heat treatment bath, the positive electrode scrap comprising a lithium composite transition metal oxide positive electrode active material layer on a current collector; removing a binder and a conductive material in the active material layer by performing heat treatment in air on the positive electrode scrap while rotating the positive electrode scrap around an axis of a rod in the heat treatment bath, and separating the current collector from the active material layer; recovering an active material in powder form that has passed through a screening wall; and annealing the active material in the air at 400 to 1000°C to obtain a reusable active material.

11. The positive electrode active material reuse method of claim 10, wherein the heat treatment is performed at 300 to 650°C.

12. The positive electrode active material reuse method of claim 10, further comprising, before the annealing, cleaning the recovered active material with a lithium compound solution showing basicity in an aqueous solution state.

13. The positive electrode active material reuse method of claim 12, wherein, before the annealing, a lithium precursor is added to the cleaned active material.

14. The positive electrode active material reuse method of claim 12, further comprising, after the cleaning, obtaining the active material to which a lithium precursor is added and of which particles are adjusted, by mixing the cleaned active material with a lithium precursor solution and spray drying the active material.

15. The positive electrode active material reuse method of claim 10, further comprising performing surface coating on the annealed active material.