KR20230169012A - Method for prepairng of recycled cathode material using waste secondary battery - Google Patents

Abstract

The present invention includes the steps of (S1) heat-treating a positive electrode plate separated from a waste secondary battery to generate Co _x O _y material; (S2) mixing a material containing lithium with the produced Co _x O _y material; (S3) Provides a method for manufacturing a recycled positive electrode active material including the step of heat treating the mixed material to form a recycled positive electrode active material, where x and y in Co _x O _y each have a value between 0 and 10.

Description

Method for manufacturing recycled cathode active material using waste secondary battery {Method for preparation of recycled cathode material using waste secondary battery}

The present invention relates to a method of manufacturing a regenerated cathode active material using waste secondary batteries, and more specifically, to a method of manufacturing a regenerated cathode active material configured to enable regeneration at a high production rate and provide an efficiency similar to that of the original secondary battery. It's about.

As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which have high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

Lithium transition metal oxide is used as a positive electrode active material for lithium secondary batteries, and among these, lithium cobalt oxide of LiCoO ₂ , lithium manganese oxide (LiMnO ₂ or LiMn ₂ O ₄ , etc.), lithium iron phosphate compound (LiFePO ₄ , etc.), or Lithium nickel oxide (LiNiO ₂ , etc.) is mainly used. However, the transition metals that make up the cathode active materials of these lithium secondary batteries, such as lithium cobalt oxide or NCM-based lithium oxide, are expensive, and cobalt in particular is a strategic metal, and countries around the world have a special interest in supply and demand. , Cobalt is known as a metal whose supply and demand are unstable worldwide due to the limited number of producing countries. In addition, these transition metals can cause environmental problems, so it is necessary to respond to environmental regulations.

The conventional method of recycling waste lithium secondary batteries selectively concentrates only waste cathode active materials through crushing, magnetic sorting, and classification, and then leaches cobalt through sulfuric acid leaching using hydrogen peroxide as a reducing agent. Next, in order to recover cobalt from the leaching solution, a process of selectively separating and recovering cobalt using oxalic acid and a process of producing cobalt sulfate through solvent extraction from the solution after removing impurities by adjusting the pH are used to produce waste lithium secondary batteries. is recycling. However, in the prior art, the method was limited to lithium cobalt oxide (LCO) among waste cathode active materials, and in the lithium nickel cobalt manganese oxide (NCM) or lithium ion manganese oxide (LMO) types for electric vehicles, which are increasingly being used, the leaching agent is only sulfuric acid. It is difficult to do this efficiently, and in the prior art, when producing cobalt using oxalic acid, it must be calcined to decompose the oxalic acid into carbon dioxide and re-dissolve the cobalt oxide in sulfuric acid to produce cobalt sulfate, so it is a preferable method in terms of cost. Can not. In addition, there are significant difficulties in wastewater treatment due to the excessive amount of oxalic acid used to selectively separate cobalt.

In another conventional technology, the cathode active material powder from which aluminum has been removed is leached with acid and then recycled only in the form of a mixed hydroxide of nickel, cobalt, and manganese through alkali precipitation, or in the form of a single hydroxide. However, the product has a high impurity content to be used as a secondary battery precursor raw material with high added value. This is a semi-finished product that lacks the value of a complete material, and has the problem of lack of actual marketability.

Therefore, in order to solve the above-mentioned problems, the present inventors recognized that it is urgent to develop a method for efficiently regenerating positive electrode active materials for secondary batteries, and completed the present invention.

Republic of Korea Patent Publication No. 10-2064668 Japanese Patent Publication No. 1999-006020

The purpose of the present invention is to provide a method for manufacturing a regenerated positive electrode active material that can be economically and easily recycled from waste secondary batteries and can provide excellent electrochemical properties.

The technical problems to be achieved by the invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description of the present invention.

In order to achieve the above object, the present invention provides a method for manufacturing a recycled positive electrode active material using waste secondary batteries.

Hereinafter, this specification will be described in more detail.

The present invention provides a method for manufacturing a recycled positive electrode active material comprising the following steps.

(S1) generating Co _x O _y material by heat treating the positive electrode plate separated from the waste secondary battery;

(S2) mixing a material containing lithium with the produced Co _x O _y material;

(S3) heat-treating the mixed materials to form a recycled positive electrode active material.

In Co _x O _y , x and y each have a value between 0 and 10.

In the present invention, the positive electrode plate separated from the waste secondary battery in step (S1) may include an active material, a conductive material, and a binder.

In the present invention, the heat treatment in step (S1) may be performed under an inert gas or reducing gas.

In the present invention, the heat treatment in step (S1) is performed at a temperature range of 510 to 750 ° C., and the anode plate is reduced by the heat treatment performed in step (S1), thereby producing Co _x O _y material. .

_{In the present invention , Co}

In the present invention, the Co _x O _y material produced in step (S1) may be CoO.

In the present invention, the Co _x O _y material produced in step (S1) may be formed in a porous structure.

In the present invention, the Co _x O _y material produced in step (S1) may include pores in the range of 0.001 to 10.0 cm ³ /g.

In the present invention, the Co _x O _y material produced in step (S1) may have a specific surface area of 0.3 to 50.0 m ² /g.

In the present invention, the lithium-containing material mixed in step (S2) may include one or more materials selected from the group consisting of LiOH, Li ₂ CO ₃ , LiNO ₃ and Li ₃ PO ₄ .

In the present invention, the material containing lithium mixed in the step (S2) may be mixed so that the molar ratio of lithium to Co in the Co _x O _y material is 1.0 to 1.06.

In the present invention, the heat treatment in step (S3) may be performed at a temperature range of 800 to 1,050 °C.

In the present invention, the heat treatment in step (S3) may be performed by dry heat treatment or wet heat treatment.

Additionally, the present invention provides a recycled positive electrode active material formed according to the above-described manufacturing method.

All matters mentioned in the above method of manufacturing a regenerated positive electrode active material using a waste secondary battery and the regenerated positive electrode active material produced thereby are equally applicable unless contradictory.

The method for manufacturing a regenerated positive electrode active material using a waste secondary battery of the present invention can economically and easily regenerate the positive electrode active material from a waste secondary battery, the electrochemical performance of the positive electrode active material is not deteriorated during the regeneration process, and excellent resistance characteristics and electrical conductivity are possible. Characteristics and capacity characteristics can be implemented.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Figure 1 is a block diagram schematically showing a method of manufacturing a recycled positive electrode active material using a waste secondary battery of the present invention.
Figure 2 is an X-ray photoelectron spectroscopy (XPS) spectrum confirming the components included in the positive electrode plate according to the present invention.
Figure 3 is a scanning electron microscope (SEM) image confirming the pores formed on CoO produced in Example 1 according to the present invention.
Figure 4 shows the X-ray diffraction (X- It is a ray diffraction (XRD) pattern.
Figure 5 is an ) is a pattern.
Figure 6 is an X-ray diffraction (XRD) pattern for CoO produced in Example 1 according to the present invention and recycled positive electrode active material (LCO) 1 manufactured using the produced CoO.
Figure 7 is a graph evaluating the electrochemical performance at 3.0 to 4.3 V for the recycled positive electrode active material and the commercial positive electrode active material prepared according to the present invention.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present invention, but this may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, etc. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the relevant invention. Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than simply the name of the term.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless clearly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

The numerical range includes the values defined in the range above. Every maximum numerical limit given throughout this specification includes all lower numerical limits as if the lower numerical limit were explicitly written out. Every minimum numerical limit given throughout this specification includes every higher numerical limit as if such higher numerical limit was clearly written. All numerical limits given throughout this specification will include all better numerical ranges within the broader numerical range, as if the narrower numerical limits were clearly written.

Hereinafter, examples of the present invention will be described in detail, but it is obvious that the present invention is not limited to the following examples.

Recycled cathode active material manufacturing method

The present invention provides a method for producing a recycled positive electrode active material comprising the following steps.

(S1) generating Co _x O _y material by heat treating the positive electrode plate separated from the waste secondary battery;

(S2) mixing a material containing lithium with the produced Co _x O _y material;

(S3) heat-treating the mixed materials to form a recycled positive electrode active material.

In Co _x O _y, x and y may each have a value of 0 to 10.

“Cathode active material” is the main component that produces electricity through chemical reactions within a secondary battery, and generally refers to an active material containing lithium oxide. When applying the positive electrode active material to the present invention, the positive electrode active material is a positive electrode active material containing lithium and cobalt, preferably LCO (LiCoO ₂ ), LCA (LiCoAlO ₂ ), LCM (LiCoMnO ₂ ), and LCMA (LiCoMnAlO ₂ ), a positive electrode active material with a layered structure consisting of LMO (LiMn ₂ O ₄ ), a spinel-structured positive electrode active material, and an olivine-structured positive electrode active material, which is LFP (LiFePO ₄ ), and preferably one or more of the above. It may be one or more layered structure positive electrode active materials selected from the group consisting of NCO, NCA, NCM, and NCMA.

The LCO is an oxide of lithium and cobalt with a layered structure and has the advantage of very high stability and lifespan.

The LCA is a layered oxide of lithium, cobalt, and aluminum, and has the advantage of being easy to apply industrially and having a long lifespan by reducing the content of expensive cobalt.

The LCM is a layered oxide of lithium, cobalt, and manganese, and has the advantage of being easy to apply industrially by reducing the content of expensive cobalt and having somewhat higher stability.

The LCMA is a layered form of oxides of lithium, cobalt, manganese, and aluminum, and can be said to be a combination of the LCA and LCM, thereby exhibiting the advantages of both the LCA and LCM.

The LMO is a spinel-structured oxide of lithium and manganese, and has the advantage of being very stable and economically very inexpensive as it does not contain expensive cobalt.

The LFP is a material containing lithium, iron, _{phosphorus , and} oxygen in an olivine structure, _and has _a relative It has the best stability and has a long lifespan, so it can be applied to various fields.

The step (S1) may be a step of generating Co _x O _y by performing a reduction heat treatment on the positive electrode plate separated from the waste secondary battery.

The positive electrode plate separated from the waste secondary battery used in step (S1) may include a positive electrode active material, a conductive material, a binder, etc. At this time, due to the conductive material and binder material present in the positive electrode plate, Co _x O _y material can be generated when heat treatment is performed in step (S1).

The binder is a component that assists the bonding of the positive electrode active material with the conductive material and the bonding to the current collector, examples of which include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVOH, PVA) , PVAI), carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose (HPMC), polyvinyl pyrrolidone, polytetrafluoroethylene (PTFE) , polyethylene (PE), polypropylene (PP), ethylene-propylene-diene terpolymers (Ethylene, Propylene, Non-conjugated Diene, Ethylene Propylene Terpolymers, EPDM), styrene butyrene rubber, fluorine rubber and various aerial It may be one or more types selected from the group consisting of combinations, but any commonly used binder can be applied without limitation.

The conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the secondary battery. For example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

The heat treatment in step (S1) is preferably performed on the anode plate at a temperature of 510 to 750 °C, and most preferably in a temperature range of 550 to 660 °C. If the heat treatment in step (S1) is performed at a temperature range of less than 510°C, sufficient reduction may not be performed properly and the initial active material phase may be maintained.

The step (S1) may be performed in an oxygen-deficient environment in which the reduction reaction can be carried out more easily, preferably in an inert gas or reducing gas atmosphere, preferably in argon (Ar), nitrogen (N ₂ ), carbon dioxide ( CO ₂ ), carbon monoxide (CO), or hydrogen (H ₂ ) may be carried out in an environment, and most preferably carried out in an argon or nitrogen environment.

_{The Co _ _ _ _}

For reference, in this specification _{, Co}

_{The Co} ^_ _{_ _}

These pores are formed by the elution of oxygen (O ₂ ) gas and lithium (Li) ions due to the reduction of the spent secondary battery, and the specific surface area of the positive electrode active material increases due to the pores, thereby reducing the amount of lithium in the production of the regenerated LCO. The effect of improving diffusion can be achieved.

Additionally, the Co _x O _y material produced in step (S1) may have a specific surface area of 0.3 to 50.0 m ² /g.

The (S2) step is _a step of _{mixing the produced Co} At least one material selected from the group consisting of Li ₃ PO ₄ may be included, preferably at least one material selected from the group consisting of Li ₂ CO ₃ , LiNO ₃ and Li ₃ PO ₄ , and most preferably may include one or more materials selected from the group consisting of Li ₂ CO ₃ and Li ₃ PO ₄ .

The material containing lithium mixed in the (S2) step may be mixed so that the molar ratio of lithium to Co (Li/Co) for Co _x O _y produced in the (S1) step is 1.0 to 1.06.

The heat treatment in step (S3) may be performed at 800 to 1,050 °C.

In addition, the heat treatment in step (S3) may be performed through dry heat treatment performed by placing the material in an oven, furnace, tube, etc. in the absence of moisture, or wet heat treatment through hydrothermal treatment.

The advantages and features of the present invention and methods for achieving them will become clear with reference to the embodiments described in detail below. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms, and only the embodiments are provided to ensure that the disclosure of the present invention is complete, and are provided by those skilled in the art It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

Example 1. Preparation of recycled positive electrode active material 1

The positive electrode plate containing the active material and additives from the waste lithium secondary battery was separated and reduced by heat treatment at 600°C with argon (Ar), an inert gas, to produce CoO with pores formed. Li ₂ CO ₃ was added (mixed) to the produced CoO at a molar ratio of 1.02:1 (Li ₂ CO ₃ :CoO:) to obtain a (S3) step of 158 mAh/g at 850°C to produce regenerated positive electrode active material (LCO) 1. was manufactured.

Example 2. Preparation of recycled positive electrode active material 2

The positive electrode plate containing the active material and additives from the waste lithium secondary battery was separated and reduced by heat treatment at 700°C with argon (Ar), an inert gas, to produce CoO with pores formed on the surface. Li ₂ CO ₃ was added (mixed) to the produced CoO at a molar ratio of 1.04:1 (Li ₂ CO ₃ :CoO:) to obtain a regenerated positive electrode active material (LCO) 2 at 158 mAh/g at 850°C through step (S3). was manufactured.

Experimental Example 1. Confirmation of separated positive electrode plate components

In order to confirm the components contained in the separated positive electrode plate in the waste lithium secondary battery, X-ray photoelectron spectroscopy (XPS) was measured on the separated positive electrode plate, and this is shown in FIG. 2.

Referring to Figure 2, it can be seen that lithium containing the active material, binder (PVDF) as an additive, electrolyte, etc. are analyzed.

Experimental Example 1. Confirmation of generated CoO surface pores

1.1. Specific surface area analyzer (Brunauer Emmett Teller, BET)

According to the present invention (S1), the positive electrode plate was separated from the waste secondary battery and heat-treated and reduced to confirm the CoO produced with pores, using a specific surface area analyzer (Brunauer Emmett Teller, BET) according to Example 1. The specific surface areas of the manufactured CoO, recycled cathode active material (LCO) 1, and commercial cathode active material (LCO) were analyzed, and are shown in [Table 1] below.

[Table 1]

Referring to [Table 1], compared to the recycled cathode active material 1 and the commercial cathode active material, pores with a denser pore size and a higher specific surface area are formed on the CoO produced in step (S1) according to the present invention. You can confirm that it has been done.

1.2. Scanning Electron Microscope (SEM)

In order to confirm CoO in which pores were formed by separating the positive electrode plate from a waste secondary battery and reducing it in step (S1) according to the present invention, pore formation images were confirmed through a scanning electron microscope for the CoO produced in Example 1. This is shown in Figure 3.

Referring to Figure 3, (a) when the CoO phase produced in Example 1 according to the present invention is enlarged, (b) it can be confirmed that pores are formed in the produced CoO, and (c) the produced It can be seen that pores are formed on the cross section of CoO. The pores may be formed by the elution of oxygen (O ₂ ) gas and lithium (Li) ions due to the reduction of the spent secondary battery. Through the above results, in the case of CoO according to the present invention, the inside and outside (surface ) It can be seen that pores have been formed throughout.

Experimental Example 2. Comparison of effects according to heat treatment in step (S1)

2.1. (S1) Comparison of step heat treatment according to gas environment

In the method for producing a recycled positive electrode active material according to the present invention, for comparison according to the gas environmental conditions of the (S1) step, Examples 1 and 2, and as a comparison group, the (S1) step were performed at 500 and 600 times under oxygen conditions. and comparative regenerated positive electrode active materials 1 to 3 were prepared at 700° C. and X-ray diffraction patterns were measured, which are shown in FIG. 4.

Referring to FIG. 4, (a) it can be seen that comparative regenerated positive electrode active materials 1 to 3 performed under oxygen conditions and at 500, 600 to 700° C. have an X-ray diffraction pattern in which only the initial active material is present regardless of the temperature range. . On the other hand, (b) regenerated positive electrode active materials 1 and 2, in which steps (S1) were performed at 600 and 700 ° C. respectively under argon gas conditions, showed an X-ray diffraction pattern in which all active materials were reduced and only cobalt oxide in the form of CoO was present. You can check it.

2.2. (S1) Comparison according to stage temperature

In the method for manufacturing a recycled positive electrode active material according to the present invention, for comparison according to the temperature range of step (S1), all conditions are the same as Examples 1 and 2 and Example 1 as a comparison group, but (S1) ) Comparative regenerated cathode active material 4 was manufactured in which only the step temperature was performed at 500°C, and the X-ray diffraction pattern was measured, which is shown in FIG. 5.

Referring to FIG. 5, it can be seen that the comparative regenerated positive electrode active material 4 in which step (S1) was performed at 500 ° C. has an X-ray diffraction pattern in which CoO and the active material coexist regardless of the temperature range. On the other hand, it can be confirmed that the regenerated positive electrode active materials 1 and 2 according to the present invention in which the (S1) step was performed at 600 and 700 ° C. showed an X-ray diffraction pattern in which all active materials were reduced and only CoO was present.

From the above results, it can be seen that in order to produce pure CoO from which impurities are completely removed through step (S1), it is most preferable to perform the process in an inert argon gas environment and a temperature range of 510 to 750 ° C.

Experimental Example 3. Confirmation of recycled positive electrode active material with layered structure

In order to confirm the structural characteristics of the recycled positive electrode active material prepared according to the present invention, was measured, and it is shown in Figure 6.

Referring to FIG. 6, it can be seen that the recycled positive electrode active material (Example 1) manufactured using CoO, which has a porous structure in which pores are formed, has a layered structure.

Experimental Example 3. Electrochemical performance evaluation of recycled positive electrode active material

In order to evaluate the electrochemical performance of the recycled positive electrode active material prepared according to the present invention, the electrochemical performance was evaluated at 3.0 to 4.3 V with respect to a commercially available positive electrode active material (LCO). The results are shown in Table 2 and Figure 7 below.

[Table 2]

Referring to [Table 2] and FIG. 7, it can be seen that the charge capacity, discharge capacity, and efficiency of the commercial positive electrode active material, recycled positive electrode active material 1, and recycled positive electrode active material 2 are almost identical within the error range. From the above results, it can be confirmed that the electrochemical performance of the positive electrode active material produced according to the present invention is not deteriorated and excellent electrochemical properties can be achieved.

From the above description, those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. In this regard, the embodiments described above should be understood in all respects as illustrative and not restrictive.

Claims (14)

(S1) generating Co _x O _y material by heat treating the positive electrode plate separated from the waste secondary battery;
(S2) mixing a material containing lithium with the produced Co _x O _y material;
(S3) heat treating the mixed material to form a recycled positive electrode active material;
In the Co _x O _y , x and y each have a value between 0 and 10,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The positive electrode plate separated from the waste secondary battery in step (S1) contains a positive electrode active material, a conductive material, and a binder,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The step (S1) is performed in an inert gas or reducing gas environment,
Method for manufacturing recycled positive electrode active material. According to paragraph 3,
The heat treatment in the (S1) step is performed in a temperature range of 510 to 750 ° C., and the anode plate is reduced by the heat treatment performed in the (S1) step to produce a Co _x O _y material,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The Co _x O _y material produced in the step (S1) includes at least one material selected from the group consisting of CoO, Co ₂ O ₃ and Co ₃ O ₄
Method for manufacturing recycled positive electrode active material. According to clause 5,
The Co _x O _y material produced in the (S1) step is CoO,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The Co _x O _y material produced in the step (S1) is formed in a porous structure,
Method for manufacturing recycled positive electrode active material. In clause 7,
The Co _x O _y material produced in step (S1) contains pores in the range of 0.001 to 10.0 cm ³ /g,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The Co _x O _y material produced in the step (S1) has a specific surface area of 0.3 to 50.0 m cm ² /g,
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The lithium-containing material mixed in step (S2) includes one or more materials selected from the group consisting of LiOH, Li ₂ CO ₃ , LiNO ₃ , and Li ₃ PO ₄ .
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The material containing lithium mixed in the (S2) step is mixed so that the molar ratio of lithium to Co is 1.0 to 1.06 with respect to the Co _x O _y material produced in the (S1) step.
Method for manufacturing recycled positive electrode active material. According to paragraph 1,
The heat treatment in step (S3) is performed in a temperature range of 800 ℃ to 1,050 ℃,
Method for manufacturing recycled positive electrode active material. According to clause 12,
The heat treatment in step (S3) is performed by dry heat treatment or wet heat treatment,
Method for manufacturing recycled positive electrode active material. A recycled positive electrode active material formed according to the manufacturing method according to any one of claims 1 to 13.