KR20240034500A - Manufacturing method of cathode active material precursor for lithium secondary battery - Google Patents

Abstract

The present invention is a method of producing a positive electrode active material precursor for a lithium secondary battery from a waste lithium secondary battery, comprising liquid nickel raw material, cobalt raw material, and manganese raw material extracted from a waste lithium secondary battery, and the nickel raw material and cobalt Preparing recycled liquid raw materials having an impurity content of 100 ppm or more for each raw material and manganese raw material; Forming a transition metal-containing solution containing the recycled liquid raw material; And adding the transition metal-containing solution, the ammonia solution, and the caustic soda solution to a reactor to form a reaction solution, and subjecting the reaction solution to a coprecipitation reaction to form a positive electrode active material precursor for a lithium secondary battery, wherein the transition metal-containing solution It relates to a method for producing a positive electrode active material precursor for a lithium secondary battery, wherein the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of the transition metal element contained therein is 1.0 to 1.6.

Description

Manufacturing method of positive electrode active material precursor for lithium secondary battery {MANUFACTURING METHOD OF CATHODE ACTIVE MATERIAL PRECURSOR FOR LITHIUM SECONDARY BATTERY}

The present invention relates to a method for manufacturing a positive electrode active material precursor for a lithium secondary battery, a positive electrode active material precursor for a lithium secondary battery, a positive electrode active material, and a lithium secondary battery containing the same, and more specifically, by utilizing liquid recycled raw materials extracted from waste lithium secondary batteries. It relates to a method of manufacturing a positive electrode active material precursor for a lithium secondary battery, a positive electrode active material precursor for a lithium secondary battery, a positive electrode active material, and a lithium secondary battery containing the same.

As demand for small electronic devices such as smartphones, laptops, and tablet PCs, as well as electric vehicles and mid- to large-sized energy storage devices, increases, the demand for secondary batteries that can store electrical energy is rapidly increasing.

In particular, the use of LiNiCoMnO2 (NCM), a three-component cathode active material, in large-capacity lithium secondary batteries for electric vehicles is expected to increase significantly. As the production and use of lithium secondary batteries increases, the amount of waste will also increase, so the need for reprocessing and recycling technology for waste lithium secondary batteries is emerging. In addition, the secondary battery and materials industry is not only making efforts to lower prices by using raw materials, low-cost processes, and improving yields, but as demand for secondary batteries increases, attempts to recycle used batteries, defective products, and electrodes generated during the manufacturing process are increasing. I'm doing it.

However, battery raw materials obtained through the recycling process have a problem with a higher impurity content compared to nickel sulfate, cobalt sulfate, and manganese sulfate, which are used as existing battery raw materials. In addition, when producing a positive electrode material using these raw materials, there is a problem that impurities exist in the structure, inhibiting the movement of lithium, and consequently inhibiting the movement of lithium ions within the electrode. As a result, there is a problem that the electrochemical performance of the lithium secondary battery, such as capacity, diffusion coefficient, resistance, and output characteristics, is significantly deteriorated.

In order to solve the above-mentioned problems, one object of the present invention is to provide excellent electrochemical performance even when manufactured using liquid nickel raw materials, cobalt raw materials, and manganese raw materials containing a large amount of impurities extracted from waste lithium secondary batteries. The present invention provides a method for manufacturing a positive electrode active material precursor for a lithium secondary battery, from which a positive electrode active material precursor can be obtained.

Another object of the present invention is to provide a positive electrode active material precursor for a lithium secondary battery manufactured through the above manufacturing method.

Another object of the present invention is to provide a positive electrode active material for a lithium secondary battery formed using the positive electrode active material precursor for a lithium secondary battery and a lithium secondary battery containing the same.

In order to achieve the above-described object, one embodiment of the present invention is a method of manufacturing a positive electrode active material precursor for a lithium secondary battery from a waste lithium secondary battery, including liquid nickel raw material, cobalt raw material, and Preparing a recycled liquid raw material containing manganese raw material and having an impurity content of 100 ppm or more for each of the nickel raw material, cobalt raw material, and manganese raw material; Dissolving the recycled liquid raw material in a solvent to form a transition metal-containing solution; And adding the transition metal-containing solution, the ammonia solution, and the caustic soda solution to a reactor to form a reaction solution, and subjecting the reaction solution to a coprecipitation reaction to form a positive electrode active material precursor for a lithium secondary battery, wherein the transition metal-containing solution A method for producing a positive electrode active material precursor for a lithium secondary battery is provided wherein the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of the transition metal element contained therein is 1.0 to 1.6.

In the step of preparing the recycled liquid raw material, the impurity content of each of the nickel raw material, cobalt raw material, and manganese raw material may be 100 to 500 ppm.

The transition metal element concentration of the transition metal-containing solution may be 2.3 to 2.6 M.

The pH of the reaction solution may be 11.1 to 11.3.

The method for producing a positive electrode active material precursor for a lithium secondary battery according to an embodiment of the present invention maintains coprecipitation reaction conditions even when liquid nickel raw material, cobalt raw material, and manganese raw material containing a large amount of impurities extracted from waste lithium secondary batteries are used. Through control, a positive electrode active material precursor with excellent electrochemical performance and a positive electrode active material formed therefrom can be manufactured.

Figure 1 shows the results of component analysis (ICP analysis results) of normal raw materials of battery grade used in manufacturing positive electrode active materials and recycled raw materials obtained through a battery recycling process.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described clearly and in detail so that those skilled in the art can easily implement the present invention. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the scope of the claims to be described later.

Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

In this specification, expressions such as “comprising” should be understood as open-ended terms that imply the possibility of including other embodiments.

As used herein, “preferred” or “preferably” refers to embodiments of the invention that may provide certain advantages under certain circumstances. However, under the same or different circumstances, other embodiments may also be preferred. Additionally, mention of one or more preferred embodiments does not mean that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

In this specification, the term "combination(s) thereof" described in the Markushi format expression refers to a mixture or combination of one or more selected from the group consisting of the components described in the Markushi format expression, It means containing one or more selected from the group consisting of constituent elements.

In this specification, the description of “A and/or B” means A or B or both.

1. Manufacturing method of positive electrode active material precursor for lithium secondary battery

The method of synthesizing NCM anode materials using conventional recycled raw materials is manufactured using a general anode material synthesis method, but there is a problem of performance degradation when a general synthesis method is applied. When applying the conventional general precursor manufacturing technology, a large amount of nuclei are generated due to impurities in the coprecipitation process, and the particle size is reduced and an unoriented precursor is obtained, which significantly reduces the performance when manufacturing the positive electrode active material.

Figure 1 shows the results of component analysis (ICP analysis results) of normal raw materials of battery grade used in manufacturing positive electrode active materials and recycled raw materials obtained through a battery recycling process.

The solid recycled raw material shown in Figure 1 represents the final product that has gone through all stages of the recycling process, and the liquid recycled raw material refers to the raw material that does not include the final crystallization step. As shown in Figure 1, it can be seen that the impurity content of the recycled raw material is as high as hundreds of ppm compared to the normal raw material, and it can be expected that this impurity content can be significantly related to performance degradation when manufacturing cathode materials.

The present invention seeks to provide a method to significantly increase the performance of existing recycled materials by changing the structure of the precursor.

More specifically, cathode materials generally have a layered structure, and a layered precursor is fired to achieve the layered structure. The unit cell structure of the layered precursor can be expressed as a length in the horizontal and vertical directions, and the height can be expressed as a length c. The physical properties of the material change significantly depending on the change in the a and c values representing this crystal structure. . It is generally known that the mobility of Li increases as the length of the c-axis increases. However, when a cathode material is manufactured using a generally known method using recycled raw materials, it was discovered that the length of the c-axis of the precursor is reduced due to impurities, which is believed to be a major factor in performance degradation.

The present invention relates to a method for dramatically improving the performance of a cathode material obtained using liquid recycled raw materials. In order to increase the c-axis length of the cathode material, the c-axis length of the coprecipitated precursor is controlled without applying doping or sintering optimization. We aim to achieve this purpose.

To achieve this goal, a special coprecipitation region in which the length of the c-axis was increased was discovered using a precursor solution with high impurities, and when coprecipitation was performed using recycled raw materials, the crystallization growth mechanism was increased and agglomeration occurred. The area that minimizes was derived. It was confirmed that under these process conditions, the c-axis length of the precursor to which the recycled solution was applied significantly increased and the performance of the cathode material was improved. In particular, it was discovered that the c-axis structure of the precursor was greatly expanded in a certain range of the amount of ammonia added, a certain concentration of the transition metal-containing solution, and a special range of the pH of the coprecipitation reaction solution, using a precursor prepared under special conditions. When the positive electrode active material was manufactured, the lithium diffusion coefficient increased, resistance characteristics decreased, and electrochemical performance improved. Under these new co-precipitation conditions, impurities are included in the precursor, the interaction between ammonia and metal is optimized, the c-axis increases, and in the case of a cathode material using the precursor manufactured through this, Li mobility increases. In the case of products using recycled liquid raw materials, it is possible to realize optimized performance of the positive electrode active material precursor and positive electrode active material by applying the coprecipitation reaction conditions according to the present invention, especially using a liquid recycled solution with an impurity content of 100 to 500 ppm. In particular, when applying this technology, it was confirmed that performance was actually improved compared to products using existing normal raw materials.

Accordingly, one embodiment of the present invention is a method of manufacturing a positive electrode active material precursor for a lithium secondary battery from a waste lithium secondary battery, comprising a liquid nickel raw material, a cobalt raw material, and a manganese raw material extracted from a waste lithium secondary battery. Preparing a recycled liquid raw material having an impurity content of 100 ppm or more for each of the nickel raw material, cobalt raw material, and manganese raw material; Forming a transition metal-containing solution containing the recycled liquid raw material; And adding the transition metal-containing solution, the ammonia solution, and the caustic soda solution to a reactor to form a reaction solution, and subjecting the reaction solution to a coprecipitation reaction to form a positive electrode active material precursor for a lithium secondary battery, wherein the transition metal-containing solution A method for producing a positive electrode active material precursor for a lithium secondary battery is provided wherein the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of the transition metal element contained therein is 1.0 to 1.6.

Hereinafter, a method for manufacturing a positive electrode active material precursor for a lithium secondary battery according to an embodiment of the present invention will be described in detail step by step.

First, recycled liquid raw materials containing liquid nickel raw materials, cobalt raw materials, and manganese raw materials extracted from waste lithium secondary batteries, and having an impurity content of 100 ppm or more for each of the nickel raw materials, cobalt raw materials, and manganese raw materials. Get ready.

More specifically, in the step of preparing the recycled liquid raw material, the impurity content of each of the nickel raw material, cobalt raw material, and manganese raw material is 100 to 500 ppm, 200 to 500 ppm, 300 to 500 ppm, 400 to 500 ppm, or 450 ppm. It may be from 500 ppm.

The nickel raw material is not particularly limited as long as it is used in the manufacture of a positive electrode active material precursor in the art. For example, the nickel raw material may be nickel-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, NiSO ₄ , NiSO ₄ ·6H ₂ O, Ni(OH) 2 , NiO, NiOOH, NiCO ₃ ·2Ni(OH) ₂ ·4H ₂ O, NiC ₂ O ₂ ·2H ₂ O, Ni(NO ₃ ) ₂ ·6H ₂ O, fatty acid nickel salt, nickel halide, or a combination thereof. However, it is not limited to this.

The cobalt raw material is not particularly limited as long as it is used in the manufacture of a positive electrode active material precursor in the art. For example, the cobalt raw material may be cobalt-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, CoSO _4, CoSO ₄ ㆍ7H ₂ O, Co(OH) ₂ , CoOOH, Co(OCOCH ₃ ) ₂ ㆍ4H ₂ O, Co(NO ₃ ) ₂ ㆍ6H ₂ O, or a combination thereof, but is not limited thereto.

The manganese raw material is not particularly limited as long as it is used in the manufacture of a positive electrode active material precursor in the art. For example, the manganese raw material may be manganese-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof, specifically MnSO ₄ , MnCO ₃ , Mn(NO ₃ ) ₂ , manganese salts such as manganese acetate, dicarboxylic acid manganese salt, manganese citrate, and fatty acid manganese salt, manganese oxide such as Mn ₂ O ₃ , MnO ₂ , and Mn ₃ O ₄ , oxyhydroxide, manganese chloride, or a combination thereof. It may be, but is not limited to this.

Next, a transition metal-containing solution containing the recycled liquid raw material is formed.

The transition metal-containing solution contains nickel raw materials, cobalt raw materials, and manganese raw materials contained in recycled liquid raw materials in a solvent, specifically water or an organic solvent that can be uniformly mixed with water (for example, alcohol, etc.). It may be manufactured by adding it to a mixed solvent, or it may be manufactured by mixing an aqueous solution of nickel raw material, an aqueous solution of cobalt raw material, and manganese raw material.

Meanwhile, the transition metal-containing solution contains nickel at 60 to 99 atm%, 70 to 99 atm%, 80 to 99 atm%, 85 to 99 atm%, 90 to 99 atm%, or 90 to 95 atm% of all transition metals. It can be included.

Additionally, the transition metal-containing solution may contain 0 to 30 atm%, 1 to 20 atm%, 1 to 10 atm%, 2 to 8 atm%, or 2 to 6 atm% of cobalt among all transition metals.

Additionally, the transition metal-containing solution may contain manganese in an amount greater than 0 and 30 atm%, 1 to 20 atm%, 1 to 10 atm%, 2 to 8 atm%, or 2 to 6 atm% of all transition metals.

Next, the transition metal-containing solution, ammonia solution, and caustic soda solution are added to the reactor to form a reaction solution, and the reaction solution is subjected to a coprecipitation reaction to form a positive electrode active material precursor for a lithium secondary battery.

The ammonia solution is a complex forming agent, for example, NH ₃ , NH ₄ OH, (NH ₄ ) ₂ SO ₄ , NH ₄ NO ₃ , NH ₄ Cl, CH ₃ COONH ₄ , NH ₄ CO ₃ or a combination thereof. It may include, but is not limited to this. Meanwhile, the ammonia solution may be used in the form of an aqueous solution, and in this case, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water may be used as the solvent.

The caustic soda solution may contain, as a precipitant or pH adjuster, an alkaline compound such as an alkali metal or alkaline earth metal hydroxide, hydrate thereof, or a combination thereof, such as NaOH, KOH, or Ca(OH) ₂ . The caustic soda solution may also be used in the form of an aqueous solution, and in this case, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water may be used as the solvent.

The coprecipitation reaction may be performed under an inert atmosphere such as nitrogen or argon.

During the coprecipitation reaction, the temperature in the reactor may be 30 to 70°C, specifically 40 to 60°C, and more specifically 45 to 55°C.

In particular, the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of the transition metal element contained in the transition metal-containing solution may be 1.0 to 1.6, and more specifically, 1.4 to 1.6.

If the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of transition metal elements contained in the transition metal-containing solution is too small or too large, the C-axis length of the active material precursor may be short, and excessive growth of the (001) crystal plane may occur. . Specifically, if the C-axis length is short, a problem may occur in which the mobility of Li is reduced. Additionally, specifically, in the case of the (001) crystal plane, it corresponds to the (003) crystal plane of the positive electrode active material manufactured using this. The (003) crystal plane of the positive electrode active material is thermodynamically stable and electrochemically inert due to its characteristics. It no longer acts as a path for lithium ions. Therefore, as the ratio of the mole number of ammonia is adjusted within the above range, lithium ion mobility is improved, and the capacity, resistance characteristics, and output characteristics of the lithium secondary battery can be further improved.

In addition, the transition metal element concentration of the transition metal-containing solution may be 2.3 to 2.6 M, and more specifically, 2.5 to 2.6 M.

If the transition metal element concentration is too small or too large, the C-axis length of the active material precursor may be short, and excessive growth of the (001) crystal plane may occur. Therefore, as the transition metal element concentration is adjusted within the above range, lithium ion mobility is improved, and the capacity, resistance characteristics, and output characteristics of the lithium secondary battery can be further improved.

Additionally, the pH of the reaction solution may be 11.1 to 11.3.

If the pH of the reaction solution is too small or too high, the C-axis length of the active material precursor may be short, and excessive growth of the (001) crystal plane may occur. Therefore, as the transition metal element concentration is adjusted within the above range, lithium ion mobility can be improved, thereby further improving the capacity, resistance characteristics, and output characteristics of the lithium secondary battery.

2. Cathode active material precursor for lithium secondary batteries

Another embodiment of the present invention includes nickel and manganese, has a C-axis length (Lc) of 4.6261 Å or more, and has a grain size in the (100) plane relative to the grain size C in the ( ₀₀₁₎ plane (001). Provided is a positive electrode active material precursor for a lithium secondary battery having a ratio of C ( _{100 )} /C ₍₀₀₁₎ of 0.301 to 0.35.

The positive electrode active material precursor for a lithium secondary battery may be manufactured according to the method for manufacturing the positive electrode active material precursor described above.

The positive electrode active material precursor according to the present invention may have a C-axis length (Lc) of 4.6261 Å or more, more specifically, 4.6291 or 4.6294 Å or more, and 4.64 or 4.63 Å or less. As the C-axis length (Lc) increases, lithium ion mobility can be improved, thereby further improving the capacity, resistance characteristics, and output characteristics of the lithium secondary battery.

The positive electrode active material precursor according to the present invention has C ₍ 100) / C (001), which is the ratio of the grain size C ₍₁₀₀₎ on the ( ₁₀₀ ) plane to the grain size C (001) on the ₍₀₀₁₎ plane, of 0.301 to 0.35. , more specifically, it may be 0.320 to 0.35 or 0.323 to 0.35. If C ₍₁₀₀₎ /C ₍₀₀₁₎ is too small, it means that too much growth of the (001) crystal plane occurs, which may lower the lithium ion mobility and reduce the capacity, resistance characteristics, and output characteristics of the lithium secondary battery. there is. If C ₍₁₀₀₎ /C ₍₀₀₁₎ is too large, the movement distance of Li within the particle crystal becomes too long, which may cause a problem in which resistance increases rapidly.

The positive electrode active material precursor for a lithium secondary battery has C (101) / C (001 _{), which is the ratio of the grain size C (101} ) on the ( ₁₀₁ ) plane to the grain size C ( ₀₀₁ ) on the ₍₀₀₁₎ plane, of 1.033 to 1.05. It may be, and more specifically, it may be 1.039 to 1.05 or 1.040 to 1.05. If C ₍₁₀₁₎ /C ₍₀₀₁₎ is too small, this means that too much growth of the (001) crystal plane occurs, and the lithium ion mobility will decrease, which will lead to a decrease in the capacity, resistance characteristics, and output characteristics of the lithium secondary battery. You can. If C ₍₁₀₁₎ /C ₍₀₀₁₎ is too large, the movement distance of Li within the particle crystal becomes too long, which may cause a problem in which resistance increases rapidly.

The positive electrode active material precursor for a lithium secondary battery has C (102) / C _{(001), which is the ratio of the grain size C (} 102) on the ( ₁₀₂ ) plane to the grain size C ( ₀₀₁ ) on the ₍₀₀₁₎ plane, of 0.43 to 0.48. It may be, and more specifically, it may be 0.447 to 0.48 or 0.449 to 0.48. If C ₍₁₀₂₎ /C ₍₀₀₁₎ is too small, this means that too much growth of the (001) crystal plane occurs, and the lithium ion mobility will decrease, leading to a decrease in the capacity, resistance characteristics, and output characteristics of the lithium secondary battery. You can. If C ₍₁₀₂₎ /C ₍₀₀₁₎ is too large, the movement distance of Li in the ab plane (xy plane) direction within the particle crystal becomes too long, which may cause a problem in which resistance increases rapidly.

The positive electrode active material precursor for a lithium secondary battery may be represented by the following formula (1).

[Formula 1]

Ni _x1 Co _y1 Mn _z1 (OH) ₂

In Formula 1,

0.6≤x1≤0.99, 0≤y1≤0.3, 0<z1≤0.3.

The x1 represents the molar ratio of nickel among all metal elements in the transition metal hydroxide, 0.6≤x1≤0.99, 0.7≤x1≤0.99, 0.80≤x1≤0.99, 0.85≤x1≤0.99, 0.90≤x1≤0.99 or 0.90. It may be ≤x1≤0.95. When the nickel content in the transition metal hydroxide satisfies the above range, a positive electrode active material and lithium secondary battery with high capacity characteristics can be manufactured.

The y1 represents the molar ratio of cobalt among all metal elements in the transition metal hydroxide, and may be 0≤y1≤0.3, 0.01≤y1≤0.2, 0.01≤y1≤0.1, 0.02≤y1≤0.08 or 0.02≤y1≤0.06. there is.

The z1 represents the molar ratio of manganese among all metal elements in the transition metal hydroxide, and may be 0<z1≤0.3, 0.01≤z1≤0.2, 0.01≤z1≤0.1, 0.02≤z1≤0.08 or 0.02≤z1≤0.06. there is.

3. Cathode active material for lithium secondary batteries

Next, a positive electrode active material and a method for manufacturing the same according to another embodiment of the present invention will be described.

A positive electrode active material according to another embodiment of the present invention includes the steps of mixing the above-described positive electrode active material precursor and a lithium raw material to form a mixture; It can be prepared by calcining the mixture to form lithium transition metal oxide.

The lithium raw material may be lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the lithium raw materials are Li ₂ CO ₃ , LiNO ₃ , LiNO ₂ , LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH ₃ COOLi, Li ₂ O, Li ₂ SO ₄ , CH ₃ COOLi , Li ₃ C ₆ H ₅ O ₇ or a combination thereof, but is not limited thereto.

At this time, in the step of forming the mixture, doping raw materials may be further mixed.

The doping raw material may be a doping raw material containing Nb, Zr, Ti, Mg, Al, W, Mo, B, Ta, or a combination thereof.

The firing may be performed at 600 to 900°C, more specifically, 600 to 800°C, 700 to 800°C, or 720 to 760°C.

The firing may be performed for 5 to 20 hours, more specifically, 5 to 15 hours or 8 to 12 hours.

If necessary, the firing may be divided into primary firing and secondary firing.

The positive electrode active material for a lithium secondary battery according to another embodiment of the present invention prepared in this way includes a lithium transition metal oxide containing nickel, cobalt, and manganese, has a c-axis length (Lc) of 14.1977 Å or more, and a Lc/La, the ratio of the c-axis length (Lc) to the axis length (La), is 4.938 to 4.970.

The positive electrode active material for a lithium secondary battery according to the present invention has a c-axis length (Lc) of 14.1977 Å or more, and more specifically, may be 14.1980 Å or more, 14.1982 Å or more, or 14.1983 Å or more, and may be 15 Å or less, 14.6 Å or less, and 14.4 Å. It may be less than or equal to 14.2 Å. If the c-axis length (Lc) of the positive electrode active material is too short, lithium ion mobility may decrease and the capacity, resistance characteristics, and output characteristics of the lithium secondary battery may deteriorate, and if the c-axis length (Lc) of the positive electrode active material is too long, When Li is inserted into an electrode, resistance is high and electrode capacity is low due to a decrease in interaction with the transition metal.

In addition, the cathode active material for a lithium secondary battery according to the present invention has Lc/La, the ratio of the c-axis length (Lc) to the a-axis length (La), of 4.938 to 4.970, more specifically 4.94 to 4.970, 4.941 to 4.970, or 4.944. It may be from 4.970 to 4.970. If Lc/La is too small, it means that the Lc value is small, and lithium ion mobility may decrease, which may deteriorate the capacity, resistance characteristics, and output characteristics of the lithium secondary battery. If Lc/La is too large, the When Li is inserted into the electrode due to poor interaction, the resistance becomes high and the electrode capacity becomes low.

Meanwhile, the cation mixing index ratio of nickel cations in the lithium layer in the structure of the lithium transition metal oxide may be 1.195 to 1.4, and more specifically, 1.20 to 1.4 or 1.21 to 1.3. If the cation mixing index ratio is too large, the Li layer can easily collapse during charging and discharging, which greatly reduces battery cycle characteristics. If the cation mixing ratio is too small, the irreversible site in the bulk portion of the positive electrode active material may increase and lithium ion mobility may decrease, which may cause problems such as deterioration of resistance characteristics and output characteristics.

Additionally, the Li slab distance of the lithium transition metal oxide may be 2.6093 to 2.6120 Å, and more specifically, 2.6100 to 2.6120 Å, 2.6111 to 2.6120 Å, or 2.6112 to 2.6120 Å. If the Li slab distance of the lithium transition metal oxide is too short, the mobility of Li may decrease, causing problems such as reduced capacity and increased resistance. If it is too long, the resistance may decrease due to interaction with the transition metal when inserted into the electrode. If this is high, problems such as low capacity may occur.

The lithium transition metal oxide may be represented by the following formula (2).

[Formula 2]

Li _a [Ni _x2 Co _y2 Mn _z2 ] _(1-b) M _b O ₂

In Formula 2, 0.8≤a≤1.2, 0.6≤x2≤0.99, 0≤y2≤0.3, 0<z2≤0.3, 0≤b≤0.1, and M, the doping element, is Nb, Zr, Ti, Mg, Al. , W, Mo, B, Ta, P, Mo or a combination thereof.

The a represents the molar ratio of lithium in the lithium transition metal oxide, and may be 0.8≤a≤1.2, 0.85≤a≤1.15, or 0.9≤a≤1.1.

The x2 represents the molar ratio of nickel to the total number of moles of transition metal in the lithium transition metal oxide, 0.60≤x2≤0.99, 0.70≤x2≤0.99, 0.80≤x2≤0.99, 0.85≤x2≤0.99, 0.90≤x1≤0.99 Or it may be 0.90≤x2≤0.95. When the nickel content in the lithium transition metal oxide satisfies the above range, a positive electrode active material and a lithium secondary battery having high capacity characteristics can be manufactured.

The y2 represents the molar ratio of cobalt to the total number of moles of transition metal in the lithium transition metal oxide, 0≤y2≤0.3, 0.01≤y2≤0.2, 0.01≤y2≤0.1, 0.02≤y2≤0.08 or 0.02≤y2≤0.06. It can be.

The z2 represents the molar ratio of manganese to the total number of moles of transition metal in the lithium transition metal oxide, 0<z2≤0.3, 0.01≤z2≤0.2, 0.01≤z2≤0.1, 0.02≤z2≤0.08 or 0.02≤z2≤0.06. It can be.

The b represents the molar ratio of M, a doping element in lithium transition metal oxide, and may be 0≤b≤0.1 or 0≤b≤0.06.

4. Anode for lithium secondary battery and lithium secondary battery

Meanwhile, another embodiment of the present invention provides a positive electrode for a lithium secondary battery containing the above-described positive electrode active material for a lithium secondary battery, and a lithium secondary battery containing the positive electrode.

Specifically, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode active material.

In the positive electrode, the positive electrode current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, for example, stainless steel, aluminum, nickel, titanium, fired carbon, or carbon on the surface of aluminum or stainless steel. , surface treated with nickel, titanium, silver, etc. can be used. Additionally, the positive electrode current collector may typically have a thickness of 3 to 500㎛, and fine irregularities may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. For example, it can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

The positive electrode active material layer may include the previously described positive active material, a conductive material, and a binder.

At this time, the conductive material is used to provide conductivity to the electrode, and can be used without particular restrictions in the battery being constructed as long as it does not cause chemical change and has electronic conductivity. Specific examples include graphite such as natural graphite or artificial graphite; Carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; Metal powders or metal fibers such as copper, nickel, aluminum, and silver; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Or conductive polymers such as polyphenylene derivatives, etc., of which one type alone or a mixture of two or more types may be used. The conductive material may typically be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.

Additionally, the binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, and carboxymethyl cellulose (CMC). ), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, Examples include styrene butadiene rubber (SBR), fluorine rubber, and various copolymers thereof, and one type of these may be used alone or a mixture of two or more types may be used. The binder may be included in an amount of 1 to 30% by weight based on the total weight of the positive electrode active material layer.

The positive electrode can be manufactured according to a conventional positive electrode manufacturing method except for using the positive electrode active material described above.

Specifically, it can be manufactured by applying a composition for forming a positive electrode active material layer including the above-mentioned positive electrode active material and optionally a binder, a conductive material, and a solvent onto a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive material are the same as described above.

The solvent may be a solvent commonly used in the art, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. and the like, and one type of these may be used alone or a mixture of two or more types may be used. The amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder in consideration of the application thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied for subsequent positive electrode production. do.

Alternatively, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support and then laminating the film obtained by peeling from the support on a positive electrode current collector.

Another embodiment of the present invention provides a lithium secondary battery including the above-described positive electrode.

The lithium secondary battery may specifically include a positive electrode, a negative electrode positioned opposite the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, and the positive electrode is as described above. Additionally, the lithium secondary battery may optionally further include a battery container that accommodates the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

In the lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, it can be used on the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel. Surface treatment with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector may typically have a thickness of 3 to 500㎛, and like the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven materials.

The negative electrode active material layer may optionally include a binder and a conductive material along with the negative electrode active material. As an example, the negative electrode active material layer is formed by applying and drying a composition for forming a negative electrode active material layer including a negative electrode active material and optionally a binder and a conductive material on a negative electrode current collector, or casting the negative electrode forming composition on a separate support. It may then be manufactured by peeling off the support and laminating the obtained film onto the negative electrode current collector.

A compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; Metallic compounds that can be alloyed with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; Metal oxides that can dope and undope lithium, such as SiOβ (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; Alternatively, a composite containing the above-described metallic compound and a carbonaceous material, such as a Si-C composite or Sn-C composite, may be used, and any one or a mixture of two or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Additionally, both low-crystalline carbon and high-crystalline carbon can be used as the carbon material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and high-crystalline carbon includes amorphous, plate-shaped, flaky, spherical, or fibrous natural graphite, artificial graphite, and Kish graphite. graphite, pyrolytic carbon, mesophase pitch based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch. Representative examples include high-temperature calcined carbon such as derived cokes.

The binder and conductive material may be the same as those previously described for the positive electrode.

On the other hand, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. It can be used without particular restrictions as long as it is normally used as a separator in lithium secondary batteries, and in particular, it can be used for ion movement in the electrolyte. It is desirable to have low resistance and excellent electrolyte moisturizing ability. Specifically, porous polymer films, for example, porous polymer films made of polyolefin polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer, or these. A laminated structure of two or more layers may be used. In addition, conventional porous non-woven fabrics, such as non-woven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers, etc., may be used. Additionally, a coated separator containing a ceramic component or polymer material may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

In addition, in the lithium secondary battery, the electrolyte may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used when manufacturing a lithium secondary battery. It is not limited to.

Specifically, the electrolyte may include an organic solvent and a lithium salt.

The organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; Ether-based solvents such as dibutyl ether or tetrahydrofuran; Ketone-based solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), propylene carbonate (propylene carbonate) Carbonate-based solvents such as PC); Alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a C2 to C20 straight-chain, branched or ring-structured hydrocarbon group and may include a double bond aromatic ring or ether bond); Amides such as dimethylformamide; Dioxolanes such as 1,3-dioxolane; Alternatively, sulfolane, etc. may be used. Among these, carbonate-based solvents are preferable, and cyclic carbonates (e.g., ethylene carbonate or propylene carbonate, etc.) with high ionic conductivity and high dielectric constant that can improve the charge/discharge performance of the battery, and low-viscosity linear carbonate-based compounds ( For example, ethylmethyl carbonate, dimethyl carbonate, diethyl carbonate, etc.) are more preferable. In this case, excellent electrolyte performance can be obtained by mixing cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9.

The lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions used in lithium secondary batteries. Specifically, the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ . LiCl, LiI, or LiB(C ₂ O ₄ ) ₂ may be used. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0M. When the concentration of lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so excellent electrolyte performance can be achieved and lithium ions can move effectively.

In addition to the electrolyte components, the electrolyte includes, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, and trifluoroethylene for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity. Ethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexamethyl phosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imide One or more additives such as dazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, or aluminum trichloride may be further included. At this time, the additive may be included in an amount of 0.1 to 5% by weight based on the total weight of the electrolyte.

As described above, the lithium secondary battery containing the positive electrode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity maintenance rate, and is therefore widely used in portable devices such as mobile phones, laptop computers, digital cameras, and hybrid electric vehicles ( It is useful in electric vehicle fields such as hybrid electric vehicle (HEV).

Accordingly, another embodiment of the present invention provides a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.

The battery module or battery pack is a power tool; Electric vehicles, including electric vehicles (EV), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEV); Alternatively, it can be used as a power source for any one or more mid- to large-sized devices among power storage systems.

Hereinafter, embodiments of the present invention will be described in more detail through examples. However, the following example is only a preferred example of the present invention, and the present invention is not limited by the following example.

Examples 1-1 to 1-4

The following procedures were conducted to evaluate structural changes in precursors and active materials and lithium secondary battery performance according to ammonia mole ratio in precursors manufactured using recycled liquid raw materials.

(1) Production of positive electrode active material precursor

A transition metal-containing solution was prepared by mixing recycled liquid raw materials, nickel sulfate (impurity content 450 ppm), cobalt sulfate (impurity content 465 ppm), and manganese sulfate (impurity content 485 ppm) at a molar ratio of 92:4:4. At this time, the transition metal element concentration of the transition metal-containing solution was set to 2.5M. In addition, the molar ratio of ammonia to the total number of moles of elements of the transition metal was 1 (Example 1-1), 1.2 (Example 1-2), 1.4 (Example 1-3), and 1.6 (Example 1-4), respectively. ) was adjusted to prepare an ammonia solution.

Then, the transition metal-containing solution, ammonia solution, and distilled water were added to the coprecipitation reactor, and then nitrogen gas was supplied to the reactor to remove dissolved oxygen and perform a coprecipitation reaction while maintaining the temperature of the reactor at 50°C and stirring at 550 rpm to produce an anode. An active material precursor was prepared. At this time, the pH of the reaction solution during the coprecipitation reaction was set to 11.3.

(2) Manufacture of positive electrode active material

The positive electrode active material precursor prepared above and LiOH, a lithium raw material, were mixed at a molar ratio of 1:1.10 and then calcined in an oxygen atmosphere at a temperature of 740°C for 10 hours to prepare a lithium transition metal oxide positive electrode active material.

(3) Lithium secondary battery manufacturing

A positive electrode active material slurry was prepared by using the positive electrode active material prepared above, SuperC as a conductive material, and PVDF as a binder, and mixing the positive electrode active material, conductive material, and binder at a weight ratio of 96.5:1.5:2. The slurry was uniformly applied to aluminum foil with a thickness of 20 μm and vacuum dried at 130°C to prepare a positive electrode.

A coin battery was manufactured using the manufactured positive electrode as a working electrode, lithium foil as a counter electrode, a polypropylene membrane as a separator, and an electrolyte in which 1.0 M LiPF- ₆ lithium salt was dissolved in an EC/EMC/DMC solvent.

Comparative Examples 1-1 to 1-3

A transition metal-containing solution was prepared using nickel sulfate (impurity content 2.8 ppm), cobalt sulfate (impurity content 3.8 ppm), and manganese sulfate (impurity content 2.9 ppm) as normal raw materials, rather than recycled raw materials with high impurity content. The ratio of ammonia to the total number of moles of elements of the transition metal was adjusted to the conventionally generally used appropriate ratios of 0.4 (Comparative Example 1-1), 0.6 (Comparative Example 1-2), and 0.8 (Comparative Example 1-3) to obtain ammonia. A positive electrode active material precursor, a positive active material, and a lithium secondary battery were manufactured in the same manner as Example 1-1, except that a solution was prepared.

Comparative Examples 1-4 to 1-6

Except that the ammonia solution was prepared by adjusting the ratio of ammonia to the total number of moles of transition metal elements to 0.8 (Comparative Example 1-4), 1.8 (Comparative Example 1-5), and 2 (Comparative Example 1-6), respectively. A positive electrode active material precursor, a positive electrode active material, and a lithium secondary battery were manufactured in the same manner as in Example 1-1.

Experimental Example 1-1: Evaluation of positive electrode active material precursor structure according to ammonia mole ratio

C-axis length, C ₍₁₀₀₎ /C _(001), C ₍₁₀₁₎ /C ₍₀₀₁₎ of the positive electrode active material precursor prepared according to Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-6 and C ₍₁₀₂₎ /C ₍₀₀₁₎ evaluation experiments were conducted, and the results are shown in Table 1 below. The specific experimental method is as follows.

(1) C-axis length measurement

To analyze the crystal structure of the precursor and positive electrode active material, the X-ray diffraction phenomenon is measured using a powder did.

(2) C ₍₁₀₀₎ /C _(001), C ₍₁₀₁₎ /C ₍₀₀₁₎ and C ₍₁₀₂₎ /C ₍₀₀₁₎ measurements

After performing an The peak intensity ratio of /(001) was obtained.

precursor Raw material type ammonia rain Lc (Å) (100)/(001) (101)/(001) (102)/(001) Comparative Example 1-1 normal product 0.4 4.6291 0.321 1.044 0.445 Comparative Example 1-2 normal product 0.6 4.6297 0.325 1.047 0.449 Comparative Example 1-3 normal product 0.8 4.6294 0.329 1.045 0.451 Comparative Example 1-4 recycled liquid 0.8 4.6257 0.295 1.034 0.433 Example 1-1 recycled liquid One 4.6264 0.301 1.036 0.434 Example 1-2 recycled liquid 1.2 4.6272 0.304 1.033 0.43 Example 1-3 recycled liquid 1.4 4.6291 0.323 1.047 0.449 Example 1-4 recycled liquid 1.6 4.6295 0.329 1.045 0.45 Comparative Example 1-5 recycled liquid 1.8 4.6266 0.299 1.031 0.428 Comparative Example 1-6 recycled liquid 2 4.6258 0.296 1.03 0.427

From Table 1, in the case of Examples 1-1 to 1-4 in which the ammonia ratio is 1 to 1.6, the c-axis length, C ₍₁₀₀₎ / C _(001), compared to Comparative Examples 1-4 to 1-6 outside the above range. It was confirmed that C ₍₁₀₁₎ /C ₍₀₀₁₎ and C ₍₁₀₂₎ /C ₍₀₀₁₎ were large. In particular, for Examples 1-3 to 1-4 where the ammonia ratio is 1.4 to 1.6, the c-axis length, C ₍₁₀₀₎ / C _(001), C ₍₁₀₁₎ / C ₍₀₀₁₎ and C ₍₁₀₂₎ / It was confirmed that C ₍₀₀₁₎ was at the same level as, or rather superior to, the active material precursor using a normal product.

Experimental Example 1-2: Evaluation of positive electrode active material structure according to ammonia mole ratio

C-axis length (Lc) of the positive electrode active materials prepared according to Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-6, Lc being the ratio of c-axis length (Lc) to a-axis length (La) /La, cation mixing ratio and Li slab distance evaluation experiments were conducted, and the results are shown in Table 2 below. The specific experimental method is as follows.

(1) c-axis length, Lc/La measurement

To analyze the crystal structure of the precursor and positive electrode active material, the X-ray diffraction phenomenon was measured using an Lc/La was expressed as the ratio of the obtained c and a lattice constant values.

(2) Measurement of cation mixing ratio

The cation mixing index value was obtained by calculating the (003) and (104) diffraction peak intensity ratio from the diffraction pattern results obtained after measuring the X-ray diffraction phenomenon using an XRD measuring device (X-ray diffractometer).

(3) Li slab distance measurement

The diffraction pattern results obtained after measuring the X-ray diffraction phenomenon using an

active material Raw material type ammonia rain Lc (Å) Lc/La Cation mixing index
(003)/(104) Li slab distance
(Å) Comparative Example 1-1 normal product 0.4 14.198 4.943 1.208 2.6107 Comparative Example 1-2 normal product 0.6 14.1983 4.946 1.21 2.6109 Comparative Example 1-3 normal product 0.8 14.1984 4.945 1.213 2.611 Comparative Example 1-4 recycled liquid 0.8 14.1976 4.937 1.194 2.6092 Example 1-1 recycled liquid One 14.1978 4.939 1.195 2.6093 Example 1-2 recycled liquid 1.2 14.1977 4.943 1.198 2.6097 Example 1-3 recycled liquid 1.4 14.1984 4.944 1.213 2.611 Example 1-4 recycled liquid 1.6 14.1986 4.946 1.215 2.6112 Comparative Example 1-5 recycled liquid 1.8 14.1975 4.94 1.19 2.6095 Comparative Example 1-6 recycled liquid 2 14.1974 4.941 1.187 2.6089

From Table 2, it can be seen that in the case of Examples 1-1 to 1-4 in which the ammonia ratio is 1 to 1.6, the c-axis length and Lc / La are generally larger than in Comparative Examples 1-4 to 1-6 outside the above range. there was. In particular, in the case of Examples 1-3 to 1-4 where the ammonia ratio was 1.4 to 1.6, it was confirmed that the c-axis length and Lc/La were at the same level or rather greater than those of the active material used as a normal product.

Experimental Example 1-3: Evaluation of lithium secondary battery electrochemical properties according to ammonia mole ratio

Experiments were conducted to evaluate the initial discharge capacity, diffusion coefficient, resistance, room temperature output characteristics, and capacity retention rate of lithium secondary batteries manufactured according to Examples 1-1 to 1-4 and Comparative Examples 1-1 to 1-6, and the results were is shown in Table 3 below. The specific experimental method is as follows.

(1) Initial discharge capacity measurement

The initial capacity was measured using a constant current charge/discharge method at 0.1C within a voltage range of 2.5 to 4.25 V.

(2) Diffusion coefficient measurement

After charging and discharging at 0.1C constant current within the voltage range of 2.5 to 4.25 V, the diffusion coefficient was expressed using the following equation using the GITT method (galvanostatic intermittent titration technique).

m _B : Molecular weight of electrode active material (g/mol)

M _B : Weight of electrode active material (g)

V _M : molar volume of active material (m ³ /mol)

S: Surface area of electrode material (m ² /g)

L: Electrode thickness (m)

υ: Characteristic time for diffusion (sec)

ΔE _s : Voltage difference (V) depending on surface polarization

ΔEυ: Voltage difference (V) according to concentration polarization

(3) Resistance measurement

DCIR resistance was measured using the direct current voltage and direct current values at 60 seconds of discharge obtained through 0.1C constant current charging and discharging within a voltage range of 2.5 to 4.25 V.

(4) Measurement of room temperature output characteristics

During the constant current discharge process within a voltage of 2.5 to 4.25 V, the C-rate was measured by changing from 0.1C to 2C (standard capacity: 200mAh/g), and the room temperature output was expressed as a 2C capacity value compared to a 0.1C capacity.

(5) Capacity maintenance rate measurement

After a formation cycle of 0.2 C constant current charge and discharge within a voltage of 2.5 to 4.25 V, a constant current charge and discharge test was performed at 0.33 C, and the capacity retention rate was expressed through the 30th cycle capacity compared to the first cycle capacity.

secondary battery Raw material type ammonia rain Initial discharge capacity
(mAh/g) diffusion coefficient
( ^cm2 /s) DCIR (Ω) Room temperature output
(2C/0.1C, %) Capacity maintenance rate
(%) Comparative Example 1-1 normal product 0.4 210.5 5.30*10 ^-10 17.3 87.2 87.9 Comparative Example 1-2 normal product 0.6 210.8 5.32*10 ^-10 17.1 88.3 88.1 Comparative Example 1-3 normal product 0.8 211 5.33*10 ^-10 17.4 88.9 88 Comparative Example 1-4 recycled liquid 0.8 206.3 4.97*10 ^-10 18.5 85.7 84.8 Example 1-1 recycled liquid One 209.1 5.15*10 ^-10 18.3 87.9 87 Example 1-2 recycled liquid 1.2 209.3 5.11*10 ^-10 18.3 88 87.9 Example 1-3 recycled liquid 1.4 210.9 5.34*10 ^-10 16.9 89.5 89.1 Example 1-4 recycled liquid 1.6 212.4 5.37*10 ^-10 17.1 90.1 89.7 Comparative Example 1-5 recycled liquid 1.8 206.6 4.97*10 ^-10 18.6 86.1 85.8 Comparative Example 1-6 recycled liquid 2 205.5 4.88*10 ^-10 19.1 84.8 84.5

From Table 3, in the case of Examples 1-1 to 1-4 in which the ammonia ratio is 1 to 1.6, the overall initial discharge capacity, diffusion coefficient, resistance, and room temperature output characteristics are compared to Comparative Examples 1-4 to 1-6 in which the ammonia ratio is outside the above range. It was confirmed that the capacity maintenance rate was excellent. In particular, in the case of Examples 1-3 to 1-4 where the ammonia ratio is 1.4 to 1.6, the initial discharge capacity, diffusion coefficient, resistance, room temperature output characteristics, and capacity retention rate were equivalent to or better than those of lithium secondary batteries using normal products. I was able to confirm.

Examples 2-1 to 2-3

(1) Production of positive electrode active material precursor

A transition metal-containing solution was prepared by mixing recycled liquid raw materials, nickel sulfate (impurity content 450 ppm), cobalt sulfate (impurity content 465 ppm), and manganese sulfate (impurity content 485 ppm) at a molar ratio of 92:4:4. At this time, the transition metal element concentration of the transition metal-containing solution was set to 2.3M (Example 2-1), 2.5M (Example 2-2), and 2.6M (Example 2-3), respectively. Then, an ammonia solution was prepared by adjusting the ratio of moles of ammonia to the total moles of elements of the transition metal to 1.4.

Then, the transition metal-containing solution, ammonia solution, and distilled water were added to the coprecipitation reactor, and then nitrogen gas was supplied to the reactor to remove dissolved oxygen and perform a coprecipitation reaction while maintaining the temperature of the reactor at 50°C and stirring at 550 rpm to produce an anode. An active material precursor was prepared. At this time, the pH of the reaction solution during the coprecipitation reaction was set to 11.3.

(2) Manufacture of positive electrode active material

The positive electrode active material precursor prepared above and LiOH, a lithium raw material, were mixed at a molar ratio of 1:1.10 and then calcined in an oxygen atmosphere at a temperature of 740°C for 10 hours to prepare a lithium transition metal oxide positive electrode active material.

(3) Lithium secondary battery manufacturing

A positive electrode active material slurry was prepared by using the positive electrode active material prepared above, SuperC as a conductive material, and PVDF as a binder, and mixing the positive electrode active material, conductive material, and binder at a weight ratio of 96.5:1.5:2. The slurry was uniformly applied to aluminum foil with a thickness of 20 μm and vacuum dried at 130°C to prepare a positive electrode.

A coin battery was manufactured using the manufactured positive electrode as a working electrode, lithium foil as a counter electrode, a polypropylene membrane as a separator, and an electrolyte in which 1.0M LiPF ₆ lithium salt was dissolved in an EC/EMC/DMC solvent.

Comparative Examples 2-1 to 2-3

A transition metal-containing solution was prepared using nickel sulfate (impurity content 2.8 ppm), cobalt sulfate (impurity content 3.8 ppm), and manganese sulfate (impurity content 2.9 ppm) as normal raw materials, rather than recycled raw materials with high impurity content. The ratio of ammonia to the total number of moles of transition metal elements was set to 0.8, an appropriate ratio commonly used in the past, and the concentration of the transition metal element in the transition metal-containing solution was 1.5M, an appropriate concentration commonly used in the past (Comparative Example 2-1). , 2M (Comparative Example 2-2), 2.3M (Comparative Example 2-3), and prepared in the same manner as Example 2-1, except that the transition metal-containing solution was prepared to produce a positive electrode active material precursor, a positive electrode active material, and A lithium secondary battery was manufactured.

Reference Examples 2-1 to 2-3

Example 2-, except that the transition metal element concentration of the transition metal-containing solution was 1.5M (Reference Example 2-1), 2M (Reference Example 2-2), and 2.7M (Reference Example 2-3), respectively. A positive electrode active material precursor, a positive active material, and a lithium secondary battery were manufactured in the same manner as in 1.

Experimental Example 2-1: Evaluation of positive electrode active material precursor structure according to transition metal element concentration

C-axis length, C ₍₁₀₀₎ / C ₍₀₀₁₎ of the positive electrode active material precursor prepared according to Examples 2-1 to 2-3, Comparative Examples 2-1 to 2-3, and Reference Examples 2-4 to 2-6 _, C ₍₁₀₁₎ /C ₍₀₀₁₎ and C ₍₁₀₂₎ /C ₍₀₀₁₎ evaluation experiments were conducted, and the results are shown in Table 4 below. The specific experimental method is the same as Experimental Example 1-1.

precursor Raw material type Transition metal element concentration (M) Lc (Å) (100)/(001) (101)/(001) (102)/(001) Comparative Example 2-1 normal product 1.5 4.6296 0.329 1.043 0.45 Comparative Example 2-2 normal product 2 4.6297 0.33 1.045 0.451 Comparative Example 2-3 normal product 2.3 4.6295 0.327 1.041 0.448 Reference example 2-1 recycled liquid 1.5 1.5 4.626 0.3 1.029 Reference example 2-2 recycled liquid 2 2 4.6264 0.302 1.031 Example 2-1 recycled liquid 2.3 2.3 4.6293 0.328 1.041 Example 2-2 recycled liquid 2.5 2.5 4.6295 0.329 1.043 Example 2-3 recycled liquid 2.6 2.6 4.6294 0.325 1.039 Reference example 2-3 recycled liquid 2.7 2.7 4.627 0.31 1.03

From Table 4, in the case of Examples 2-1 to 2-3 in which the transition metal element concentration is 2.3 to 2.6M, the c-axis length, C ₍₁₀₀₎ / C, compared to Reference Examples 2-1 to 2-3 outside the above range. _(001), C ₍₁₀₁₎ /C ₍₀₀₁₎ , and C ₍₁₀₂₎ /C ₍₀₀₁₎ were confirmed to be large. In particular, for Examples 2-2 and 2-3 where the transition metal element concentration is 2.5 to 2.6M, the c-axis length, C ₍₁₀₀₎ /C _(001), C ₍₁₀₁₎ /C ₍₀₀₁₎ and C _{( 102)} It was confirmed that /C ₍₀₀₁₎ was at the same level as, or rather superior to, the active material precursor using a normal product.

Experimental Example 2-2: Evaluation of positive electrode active material structure according to transition metal element concentration

The c-axis length (Lc) and a-axis length (La) of the positive electrode active materials prepared according to Examples 2-1 to 2-3, Comparative Examples 2-1 to 2-3, and Reference Examples 2-1 to 2-3 Experiments were conducted to evaluate the c-axis length (Lc) ratio, Lc/La, cation mixing ratio, and Li slab distance, and the results are shown in Table 5 below. The specific experimental method is the same as Experimental Example 1-2.

active material Raw material type Transition metal element concentration (M) Lc (Å) Lc/La Cation mixing index
(003)/(104) Li slab distance
(Å) Comparative Example 2-1 normal product 1.5 14.1982 4.94 1.207 2.611 Comparative Example 2-2 normal product 2 14.1984 4.943 1.209 2.6112 Comparative Example 2-3 normal product 2.3 14.1982 4.941 1.205 2.6112 Reference example 2-1 recycled liquid 1.5 14.1968 4.93 1.19 2.6085 Reference example 2-2 recycled liquid 2 14.197 4.933 1.192 2.6093 Example 2-1 recycled liquid 2.3 14.1982 4.941 1.209 2.611 Example 2-2 recycled liquid 2.5 14.1985 4.944 1.211 2.6114 Example 2-3 recycled liquid 2.6 14.1984 4.941 1.204 2.611 Reference example 2-3 recycled liquid 2.7 14.1976 4.932 1.193 2.6097

From Table 5, in the case of Examples 2-1 to 2-3 where the transition metal element concentration is 2.3 to 2.6M, the c-axis length, Lc/La and Li slab distance are compared to Reference Examples 2-1 to 2-3 outside the above range. It was confirmed that it was large. In particular, in the case of Examples 2-2 to 2-3 in which the transition metal element concentration was 2.5 to 2.6M, it was confirmed that the c-axis length, Lc / La, and Li slab distance were at the same level as or rather larger than those of the active material used as a normal product. .

Experimental Example 2-3: Evaluation of lithium secondary battery electrochemical properties according to transition metal element concentration

Initial discharge capacity, diffusion coefficient, resistance, room temperature output characteristics, and A capacity maintenance rate evaluation experiment was conducted, and the results are shown in Table 6 below. The specific experimental method is the same as Experimental Example 1-3.

secondary battery Raw material
type Transition metal element concentration (M) Initial discharge capacity
(mAh/g) diffusion coefficient
( ^cm2 /s) DCIR
(Ω) Room temperature output
(2C/0.1C, %) Volume
retention rate
(%) Comparative Example 2-1 normal product 1.5 211.8 5.39*10 ^-10 17 88.7 88.1 Comparative Example 2-2 normal product 2 212 5.40*10 ^-10 17 89.1 89 Comparative Example 2-3 normal product 2.3 211.6 5.36*10 ^-10 17.2 88.5 88.7 Reference example 2-1 recycled liquid 1.5 203.5 4.93*10 ^-10 24.7 85.1 85.2 Reference example 2-2 recycled liquid 2 204.9 4.99*10 ^-10 21.2 87 87.1 Example 2-1 recycled liquid 2.3 211.4 5.34*10 ^-10 17.2 88.4 88.2 Example 2-2 recycled liquid 2.5 212.5 5.40*10 ^-10 17 89.5 89.8 Example 2-3 recycled liquid 2.6 212.2 5.37*10 ^-10 17.5 88.1 88.6 Reference example 2-3 recycled liquid 2.7 209.1 5.14*10 ^-10 19.5 86.6 87.3

From Table 6, in the case of Examples 2-1 to 2-3 in which the transition metal element concentration is 2.3 to 2.6M, the initial discharge capacity, diffusion coefficient, resistance, and room temperature output are compared to Reference Examples 2-1 to 2-3 outside the above range. It was confirmed that the characteristics and capacity retention rate were excellent. In particular, in the case of Examples 2-2 to 2-3 where the transition metal element concentration is 2.5 to 2.6, the initial discharge capacity, diffusion coefficient, resistance, room temperature output characteristics, and capacity maintenance rate are almost equivalent to those of a lithium secondary battery using a normal product. Rather, we were able to confirm that it was excellent.

Examples 3-1 to 3-2

(1) Production of positive electrode active material precursor

A transition metal-containing solution was prepared by mixing recycled liquid raw materials, nickel sulfate (impurity content 450 ppm), cobalt sulfate (impurity content 465 ppm), and manganese sulfate (impurity content 485 ppm) at a molar ratio of 92:4:4. At this time, the transition metal element concentration of the transition metal-containing solution was set to 2.5M. Then, an ammonia solution was prepared by adjusting the molar ratio of ammonia to the total molar number of elements of the transition metal to 1.0.

Then, the transition metal-containing solution, ammonia solution, and distilled water were added to the coprecipitation reactor, and then nitrogen gas was supplied to the reactor to remove dissolved oxygen and perform a coprecipitation reaction while maintaining the temperature of the reactor at 50°C and stirring at 550 rpm to produce an anode. An active material precursor was prepared. At this time, the pH of the reaction solution during the coprecipitation reaction was set to 11.1 (Example 3-1) and 11.3 (Example 3-2), respectively.

(2) Manufacture of positive electrode active material

The positive electrode active material precursor prepared above and LiOH, a lithium raw material, were mixed at a molar ratio of 1:1.10 and then calcined in an oxygen atmosphere at a temperature of 740°C for 10 hours to prepare a lithium transition metal oxide positive electrode active material.

(3) Lithium secondary battery manufacturing

A positive electrode active material slurry was prepared by using the positive electrode active material prepared above, SueprC as a conductive material, and PVDF as a binder, and mixing the positive electrode active material, conductive material, and binder at a weight ratio of 96.5:1.5:2. The slurry was uniformly applied to aluminum foil with a thickness of 20 μm and vacuum dried at 130°C to prepare a positive electrode.

A coin battery was manufactured using the manufactured positive electrode as a working electrode, lithium foil as a counter electrode, a polypropylene membrane as a separator, and an electrolyte in which 1 M LiPF ₆ lithium salt was dissolved in an EC/DMC/EMC solvent.

Comparative Examples 3-1 to 3-3

A transition metal-containing solution was prepared using nickel sulfate (impurity content 2.8 ppm), cobalt sulfate (impurity content 3.8 ppm), and manganese sulfate (impurity content 2.9 ppm) as normal raw materials, rather than recycled raw materials with high impurity content. The ratio of the moles of ammonia to the total number of moles of elements of the transition metal was set to 0.8, an appropriate ratio commonly used in the past, and the concentration of the transition metal element in the transition metal-containing solution was set to 2.3M, an appropriate concentration commonly used in the past, to prepare the transition metal-containing solution. was prepared, and the coprecipitation reaction was carried out in Example 3-1, except that the pH of the reaction solution was set to 11.5 (Comparative Example 3-1), 11.7 (Comparative Example 3-2), and 11.9 (Comparative Example 3-3), respectively. In the same manner as above, a positive electrode active material precursor, a positive electrode active material, and a lithium secondary battery were manufactured.

Reference Examples 3-1 to 3-4

Except that during the coprecipitation reaction, the pH of the reaction solution was set to 10.9 (Reference Example 3-1), 11.5 (Reference Example 3-2), 11.7 (Reference Example 3-3), and 11.9 (Reference Example 3-4), respectively. A positive electrode active material precursor, a positive electrode active material, and a lithium secondary battery were manufactured in the same manner as in Example 3-1.

Experimental Example 3-1: Evaluation of positive electrode active material precursor structure according to pH during coprecipitation reaction

C-axis length, C ₍₁₀₀₎ / C ₍₀₀₁₎ of the positive electrode active material precursor prepared according to Examples 3-1 to 3-2, Comparative Examples 3-1 to 3-3, and Reference Examples 3-1 to 3-4 _, C ₍₁₀₁₎ /C ₍₀₀₁₎ and C ₍₁₀₂₎ /C ₍₀₀₁₎ evaluation experiments were conducted, and the results are shown in Table 7 below. The specific experimental method is the same as Experimental Example 1-1.

precursor Raw material type pH Lc (Å) (100)/(001) (101)/(001) (102)/(001) Comparative Example 3-1 normal product 11.5 4.6293 0.329 1.043 0.450 Comparative Example 3-2 normal product 11.7 4.6296 0.332 1.044 0.453 Comparative Example 3-3 normal product 11.9 4.6295 0.331 1.041 0.451 Reference example 3-1 recycled liquid 10.9 4.6283 0.328 1.039 0.447 Example 3-1 recycled liquid 11.1 4.6296 0.332 1.044 0.451 Example 3-2 recycled liquid 11.3 4.6294 0.33 1.042 0.45 Reference example 3-2 recycled liquid 11.5 4.6291 0.329 1.04 0.448 Reference example 3-3 recycled liquid 11.7 4.6284 0.326 1.035 0.441 Reference example 3-4 recycled liquid 11.9 4.6272 0.323 1.032 0.438

From Table 7, in the case of Examples 3-1 to 3-2 in which the pH during the coprecipitation reaction was 11.1 to 11.3, the c-axis length, C ₍₁₀₀₎ / C _{( 001),} C ₍₁₀₁₎ /C ₍₀₀₁₎ and C ₍₁₀₂₎ /C ₍₀₀₁₎ were confirmed to be large, and in particular, the above physical properties It was confirmed that the active material precursor used as a normal product was at the same level or even superior.

Experimental Example 3-2: Evaluation of positive electrode active material structure according to pH during coprecipitation reaction

The c-axis length (Lc) and a-axis length (La) of the positive electrode active materials prepared according to Examples 3-1 to 3-2, Comparative Examples 3-1 to 3-3, and Reference Examples 3-1 to 3-4 An experiment was conducted to evaluate the c-axis length (Lc) ratio, Lc/La, cation mixing ratio, and Li slab distance, and the results are shown in Table 8 below. The specific experimental method is the same as Experimental Example 1-2.

active material
Raw material type pH Lc (Å) Lc/La Cation mixing index
(003)/(104) Li slab distance
(Å) Comparative Example 3-1 normal product 11.5 14.198 4.942 1.209 2.6112 Comparative Example 3-2 normal product 11.7 14.1983 4.945 1.213 2.6115 Comparative Example 3-3 normal product 11.9 14.1982 4.943 1.211 2.6114 Reference example 3-1 recycled liquid 10.9 14.1982 4.939 1.209 2.6109 Example 3-1 recycled liquid 11.1 14.1985 4.943 1.212 2.6115 Example 3-2 recycled liquid 11.3 14.1982 4.94 1.21 2.6113 Reference example 3-2 recycled liquid 11.5 14.198 4.936 1.208 2.6107 Reference example 3-3 recycled liquid 11.7 14.1974 4.932 1.203 2.6104 Reference example 3-4 recycled liquid 11.9 14.1971 4.926 1.193 2.6095

From Table 8, in the case of Examples 3-1 to 3-2 where the pH was 11.1 to 11.3 during the coprecipitation reaction, the c-axis length, Lc/La, and Li slab distance were lower than those of Reference Examples 3-1 to 3-4, which were outside the above range. It was confirmed that it was large, and in particular, it was confirmed that the above physical properties were at the same level as or rather greater than those of the active material using normal raw materials.

Experimental Example 3-3: Evaluation of lithium secondary battery electrochemical properties according to pH during coprecipitation reaction

Initial discharge capacity, diffusion coefficient, resistance, room temperature output characteristics, and A capacity maintenance rate evaluation experiment was conducted, and the results are shown in Table 9 below. The specific experimental method is the same as Experimental Example 1-3.

secondary battery Raw material type pH Initial discharge capacity
(mAh/g) diffusion coefficient
( ^cm2 /s) DCIR
(Ω) Room temperature output
(2C/0.1C, %) Capacity maintenance rate (%) Comparative Example 3-1 normal product 11.5 211.7 5.36*10 ^-10 17.2 89 88.5 Comparative Example 3-2 normal product 11.7 212 5.41*10 ^-10 17 89.7 88.9 Comparative Example 3-3 normal product 11.9 211.9 5.38*10 ^-10 17.1 89.3 88.3 Reference example 3-1 recycled liquid 10.9 211.8 5.34*10 ^-10 17.8 88.5 88 Example 3-1 recycled liquid 11.1 212.8 5.40*10 ^-10 16.8 89.5 89 Example 3-2 recycled liquid 11.3 212 5.37*10 ^-10 17.2 89.2 88.4 Reference example 3-2 recycled liquid 11.5 211.4 5.29*10 ^-10 18 87.5 87.5 Reference example 3-3 recycled liquid 11.7 209.6 5.21*10 ^-10 18.4 87.1 86.9 Reference example 3-4 recycled liquid 11.9 208.2 5.14*10 ^-10 19 86.1 86.5

From Table 9, in the case of Examples 3-1 to 3-2 in which the pH was 11.1 to 11.3 during the coprecipitation reaction, the initial discharge capacity, diffusion coefficient, resistance, and room temperature output characteristics compared to Reference Examples 3-1 to 3-4 outside the above range. It was confirmed that the capacity maintenance rate was excellent. In particular, it was confirmed that the electrochemical properties were almost equivalent to, or rather superior to, those of a lithium secondary battery using normal raw materials.

Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and can be implemented with various modifications within the scope of the patent claims, detailed description of the invention, and the accompanying drawings, and this can also be done in various ways. It is natural that it falls within the scope of the invention.

Accordingly, the actual scope of rights of the present invention will be defined by the attached patent claims and their equivalents.

Claims (4)

A method of producing a positive electrode active material precursor for a lithium secondary battery from a waste lithium secondary battery, comprising:
Preparing recycled liquid raw materials containing liquid nickel raw materials, cobalt raw materials, and manganese raw materials extracted from waste lithium secondary batteries, and having an impurity content of 100 ppm or more for each of the nickel raw materials, cobalt raw materials, and manganese raw materials. step;
Forming a transition metal-containing solution containing the recycled liquid raw material; and
Injecting the transition metal-containing solution, the ammonia solution, and the caustic soda solution into a reactor to form a reaction solution, and co-precipitating the reaction solution to form a positive electrode active material precursor for a lithium secondary battery,
A method of producing a positive electrode active material precursor for a lithium secondary battery, wherein the ratio of the number of moles of ammonia contained in the ammonia solution to the number of moles of the transition metal element contained in the transition metal-containing solution is 1.0 to 1.6.
According to paragraph 1,
In the step of preparing the recycled liquid raw material,
A method of producing a positive electrode active material precursor for a lithium secondary battery in which the impurity content of each of the nickel raw material, cobalt raw material, and manganese raw material is 100 to 500 ppm.
According to paragraph 1,
A method of producing a positive electrode active material precursor for a lithium secondary battery wherein the transition metal element concentration of the transition metal-containing solution is 2.3 to 2.6 M.
According to paragraph 1,
A method of producing a positive electrode active material precursor for a lithium secondary battery wherein the pH of the reaction solution is 11.1 to 11.3.