KR101919516B1 - Positive active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same - Google Patents

Abstract

The present invention provides a method for producing a positive electrode active material for a lithium secondary battery, which comprises washing a positive electrode active material containing nickel with a wash liquid containing lithium hydroxide (LiOH) and lithium nitrate (LiNO ₃ ) And a lithium secondary battery included in the positive electrode.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing a positive electrode active material for a lithium secondary battery, and a lithium secondary battery including the same. BACKGROUND ART [0002]

The present invention relates to a method for producing a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same.

The positive electrode active material, which is one of the elements constituting the lithium secondary battery, has a structure capable of releasing / inserting lithium ions in general. Among them, the cathode active material having a high manganese content shows high stability and low capacity. However, in order to realize the above-mentioned high-output large-sized battery type, it is necessary to develop a cathode active material having excellent capacity and stability.

On the other hand, the higher the nickel content of the positive electrode active material, the higher the capacity thereof. However, it is pointed out that the stability is low as compared with the cathode active material having a high manganese content, and the electrochemical capacity is lowered due to repeated charge and discharge, so that the life characteristic is poor.

Specifically, in the case of the positive electrode active material containing nickel, the oxidation number of the nickel ion changes to Ni ^{4 +} after the lithium ion is removed from the Ni ²⁺ , and Ni ^{4 +} is unstable, .

Since oxygen is generated during such a chemical change, the stability is evaluated to be low, and the nickel oxide is stable and can not exhibit its electrochemical capacity. In addition, since such a phenomenon is intensified at a higher temperature than a normal temperature, there is a problem that the stability at a high temperature and the life characteristics are further deteriorated.

In this regard, various researches have been made to improve the lifetime characteristics while ensuring a high capacity of the lithium secondary battery, but a fundamental solution to the above-mentioned problems has not yet been proposed.

It is another object of the present invention to provide a method for producing a positive electrode active material for a lithium secondary battery improved in structural stability and electrochemical characteristics, and to provide a lithium secondary battery comprising the positive electrode active material thus prepared in a positive electrode.

In one embodiment of the present invention, there is provided a method of manufacturing a lithium secondary battery including: preparing a lithium composite oxide including Ni, Co, and Mn; And washing the lithium composite oxide with water, wherein the step of washing the lithium composite oxide is performed using a wash water containing lithium hydroxide (LiOH), lithium nitrate (LiNO ₃ ), and a solvent The present invention provides a method for producing a positive electrode active material for a lithium secondary battery.

Specifically, the description of the wash liquid is as follows.

First, the content of lithium hydroxide (LiOH) in the washing liquid may be 0.0001 to 0.01 mol, more specifically 0.001 to 0.005 mol, based on 1 mol of the lithium composite oxide.

In this case, the molar ratio of lithium hydroxide (LiOH) to lithium nitrate (LiNO ₃ ) in the washing solution may be 1: 0.1 to 1:10.

The content of the solvent in the washing liquid may be 50 to 200 parts by weight, more specifically 75 to 100 parts by weight, based on 100 parts by weight of the lithium composite oxide.

The description of the lithium composite oxide as a subject of the water wash is as follows.

The total composition of the lithium composite oxide may be represented by the following formula (1).

Li _x Ni _a Co _b Mn _c M _{d d} O ₂

In the above formula (1), M1 is Zr, Mg, Al, Ni, Mn, Zn, Fe, Cr, Mo or W, Me is represented by the following formula 2, 0.90? X? 1.07, 0.7? , 0 <b? 0.3, 0 <c? 0.3, 0 <d <0.01, and a + b + c + d = 1.

Specifically, the lithium composite oxide may be a secondary particle in which two or more particles having different values of a, b, and c in Formula 1 are aggregated.

More specifically, the lithium composite oxide may have a concentration gradient of the entire metal or at least one element of at least one of Ni, Mn, and Co. In this case, preparing the lithium composite oxide containing Ni, Co, and Mn may include preparing an active material precursor including Ni, Co, and Mn by coprecipitation; And firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide.

The mixture of the active material precursor and the lithium source material may further include a doping source material, and the doping source material may be a compound containing at least one element selected from Zr, Ti, and Al, or a mixture of the above compounds.

Firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide; And then forming a coating layer on the surface of the lithium composite oxide, wherein the coating layer may comprise a compound comprising at least one element selected from the group consisting of B, Al, P and Si, or a mixture of the foregoing compounds .

Meanwhile, the step of washing the lithium composite oxide comprises: adding the lithium composite oxide to the washing liquid and stirring to prepare a slurry; And filtering the slurry to obtain a washed lithium composite oxide.

The step of adding the lithium composite oxide to the washing liquid and stirring to prepare a slurry can be carried out at a stirring rate of 50 to 200 rpm for 1 minute to 5 hours at a temperature range of 5 to 25.

Filtering the slurry to obtain a washed lithium composite oxide; Thereafter, drying the washed lithium complex oxide may further include drying the washed lithium complex oxide.

The step of drying the washed lithium composite oxide may be performed at a temperature ranging from 80 to 300 캜 for 1 minute to 30 hours.

Washing the lithium composite oxide with water; The heat treatment of the washed lithium composite oxide may be performed at a temperature ranging from 200 to 800 ° C. for 1 to 10 hours in air (Air) or may be performed in an oxygen (O ₂₎ atmosphere.

On the other hand, the mixing ratio of the lithium source material and the precursor in the step of preparing the lithium composite oxide was 0.97 to 1.07 based on the molar ratio of Li / Me (precursor). In the finally washed active material using this, the Li / Me molar ratio may be 0.97 to 1.02.

In another embodiment of the present invention, cathode; And an electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode includes the positive electrode active material prepared by the above-described method.

According to one embodiment of the present invention, by using a washing liquid containing lithium hydroxide (LiOH) and lithium nitrate (LiNO ₃ ) for a positive electrode active material containing nickel, it is possible to reduce lithium remaining on the surface have.

The positive electrode active material washed according to one embodiment of the present invention is applied to a positive electrode of a lithium secondary battery to suppress gas generation due to residual lithium during charging and discharging of the battery to improve battery safety, Life characteristics can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the initial charge / discharge characteristics of each cell (2032 coin cell) of Examples 1 to 4 and Comparative Example 1 of the present invention. FIG.
2 is an SEM photograph of a positive electrode active material of Comparative Example 1 of the present invention.
3 is a SEM photograph of the cathode active material of Example 2 of the present invention.
4 is a FIB EDX analysis photograph of the cathode active material of Example 2 of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as " including " an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

In one embodiment of the present invention, there is provided a method of manufacturing a lithium secondary battery including: preparing a lithium composite oxide including Ni, Co, and Mn; And washing the lithium composite oxide with water, wherein the step of washing the lithium composite oxide is performed using a wash water containing lithium hydroxide (LiOH), lithium nitrate (LiNO ₃ ), and a solvent The present invention provides a method for producing a positive electrode active material for a lithium secondary battery.

According to one embodiment of the present invention, by using a washing liquid containing lithium hydroxide (LiOH) and lithium nitrate (LiNO ₃ ) for a positive electrode active material containing nickel, it is possible to reduce lithium remaining on the surface have.

In addition, the cathode active material washed according to an embodiment of the present invention can be applied to a positive electrode of a lithium secondary battery to suppress gas generation due to residual lithium during charging and discharging of the battery, thereby improving battery safety.

Particularly, by using a washing liquid containing lithium hydroxide (LiOH) and lithium nitrate (LiNO ₃ ) in a solvent such as distilled water, it is possible to prevent the residual water on the surface of the water- It is possible to further reduce the lithium content of the battery, thereby improving the initial capacity of the battery and improving the lifetime characteristics. This is experimentally supported through examples, comparative examples, and evaluation examples to be described later.

Hereinafter, the washing liquid used in one embodiment of the present invention, the lithium composite oxide to be subjected to the water treatment using the same, and the characteristics of each step will be described in detail.

First, the description of the wash liquid is as follows.

The content of lithium hydroxide (LiOH) in the washing liquid may be 0.0001 to 0.01 mol based on 1 mol of the lithium composite oxide. Within this range, as the content of lithium hydroxide in the washing liquid becomes higher, the residual lithium on the surface of the cathode material is less removed and a larger amount is left.

More specifically, in the examples described below, 0.001 to 0.005 mol (mol) of lithium hydroxide (LiOH) in the wash liquor is used based on 1 mol of Li (Ni _0.9 Co _0.07 Mn _0.03 ) O ₂ oxide having a concentration gradient, , Lithium remaining on the surface of the washed positive electrode active material was effectively reduced and the effect of improving the initial capacity when applied to a battery was confirmed.

In this case, the molar ratio of lithium hydroxide (LiOH) to lithium nitrate (LiNO ₃ ) in the washing solution may be 1: 0.1 to 1:10. Within this range, as the number of moles of lithium nitrate (LiNO ₃ ) increases relative to the lithium hydroxide (LiOH), the pH becomes closer to neutrality and the ratio of lithium hydroxide in the remaining lithium increases.

The content of the solvent in the washing liquid may be 50 to 200 parts by weight, more specifically 75 to 100 parts by weight, based on 100 parts by weight of the lithium composite oxide.

More specifically, in the examples described below, when controlling the distilled water (DI water) as a solvent to 75 to 100 parts by weight based on 100 parts by weight of Li (Ni _0.9 Co _0.07 Mn _0.03 ) O ₂ oxide having a concentration gradient, The amount of lithium remaining on the surface of the positive electrode active material was effectively reduced, and the effect of improving the initial capacity when applied to a battery was confirmed.

The lithium composite oxide to be washed with water is not particularly limited, but the lithium complex oxide represented by the following general formula (1) can be used.

Li _x Ni _a Co _b Mn _c M _{d d} O ₂

In the above formula (1), M1 is Zr, Mg, Al, Ni, Mn, Zn, Fe, Cr, Mo or W, Me is represented by the following formula 2, 0.90? X? 1.07, 0.7? , 0 <b? 0.3, 0 <c? 0.3, 0 <d <0.01, and a + b + c + d = 1.

On the other hand, as noted above, the lithium composite oxide has the advantages of higher capacity as well as higher nickel content, lower stability than the cathode active material having a higher manganese content, electrochemical The secondary particles having two or more particles having different values of a, b, and c in the above formula (1) are gathered.

Specifically, the lithium composite oxide may have a concentration gradient of at least one metal or at least some elements of the Ni, Mn, and Co. At this time, the form of the concentration gradient is not particularly limited, and may be continuous or discontinuous for each element.

For example, the Ni may have a concentration gradient from the core portion to the surface portion, and may have a concentration gradient of up to 90% of the total radius. At this time, when the concentration of the core portion Ni is taken as 100 mol%, the Ni concentration of the surface portion can be gradually decreased to 40 mol%. For convenience, the Ni is taken as an example, but the description of the concentration gradient can also be applied to Mn and Co.

Preparing a lithium composite oxide comprising Ni, Co, and Mn in the presence of a concentration gradient of at least one of Ni, Mn, and Co in the lithium composite oxide; Comprising the steps of: preparing an active material precursor comprising Ni, Co, and Mn by coprecipitation; And firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide.

In particular, in the step of producing an active material precursor including Ni, Co, and Mn by co-precipitation, two or more kinds of metal solutions having different concentrations of Ni, Co, and Mn are used, Can form a gradient.

Specifically, in order to form a concentration gradient of the core-shell structure, two metal solutions having different mixing ratios of Ni, Co, and Mn may be prepared and used. Any one of the solutions may be used as a solution for forming a core, which may be gradually introduced into the reactor, and then the solution may be gradually added to the reactor after the appropriate amount of the solution has been added as a solution for forming a shell . At this time, using a solution prepared by mixing sodium hydroxide (NaOH) and ammonium hydroxide (NH ₄ OH) as precipitants in a molar ratio of 1.9: 1 to 2.2: 1 (the order of description is sodium hydroxide: ammonium hydroxide) And a solution for forming a shell and a solution for forming a shell are introduced, respectively.

Meanwhile, the mixture of the active material precursor and the lithium source material may further include a doping source material, and the doping source material may be a compound containing at least one element selected from Zr, Ti, and Al, or a mixture of the above compounds . Accordingly, the doping element due to the doping raw material can be doped in the lithium composite oxide, and the lattice structure of the lithium composite oxide can be changed, thereby contributing to improvement of the cell performance.

Firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide; And then forming a coating layer on the surface of the lithium composite oxide, wherein the coating layer may comprise a compound comprising at least one element selected from the group consisting of B, Al, P and Si, or a mixture of the foregoing compounds .

Meanwhile, the step of washing the lithium composite oxide comprises: adding the lithium composite oxide to the washing liquid and stirring to prepare a slurry; And filtering the slurry to obtain a washed lithium composite oxide.

The step of adding the lithium composite oxide to the washing liquid and stirring to prepare a slurry can be carried out at a stirring rate of 50 to 200 rpm for 1 to 5 hours at a temperature range of 5 to 25 캜 . This is a performance condition sufficient to remove residual lithium on the surface of the cathode active material while preventing lithium loss therein, but is not limited thereto.

Filtering the slurry to obtain a washed lithium composite oxide; Thereafter, drying the washed lithium complex oxide may further include drying the washed lithium complex oxide.

The step of drying the washed lithium composite oxide may be performed at a temperature ranging from 8 to 300 캜 for 1 minute to 30 hours. This is a temperature and a time range sufficient to remove moisture and the like remaining on the surface of the cathode active material treated with the washing liquid, but is not limited thereto.

Washing the lithium composite oxide with water; Thereafter, heat treating the washed lithium composite oxide may be further included.

The heat treatment of the washed lithium composite oxide may be performed in an atmosphere of air or oxygen (O ₂ ) for 1 to 10 hours at a temperature of 200 to 800 ° C.

On the other hand, the mixing ratio of the lithium source material and the precursor in the step of preparing the lithium composite oxide was 0.97 to 1.07 based on the molar ratio of Li / Me (precursor). In the finally washed active material using this, the Li / Me molar ratio may be 0.97 to 1.02.

The cathode active material prepared according to one embodiment of the present invention can be usefully used for the anode of a lithium secondary battery. The lithium secondary battery includes a cathode and an electrolyte including an anode active material together with a cathode.

The positive electrode is prepared by preparing a positive electrode active material composition by mixing a positive electrode active material according to an embodiment of the present invention, a conductive material, a binder and a solvent, and then directly coating and drying on the aluminum current collector. Or by casting the positive electrode active material composition on a separate support, then peeling the support from the support, and laminating the resulting film on an aluminum current collector.

The conductive material may be carbon black, graphite, metal powder, and the binder may include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene And mixtures thereof. Further, N-methylpyrrolidone, acetone, tetrahydrofuran, decane and the like are used as the solvent. At this time, the content of the cathode active material, the conductive material, the binder and the solvent is used at a level normally used in a lithium secondary battery.

The negative electrode is prepared by mixing an anode active material, a binder and a solvent in the same manner as in the case of the anode. The anode active material composition is directly coated on the copper current collector or cast on a separate support, and the anode active material film, Laminated. At this time, the negative electrode active material composition may further contain a conductive material if necessary.

As the negative electrode active material, a material capable of intercalating / deintercalating lithium is used. For example, lithium metal, lithium alloy, coke, artificial graphite, natural graphite, organic polymeric compound combustion material, . The conductive material, the binder and the solvent are used in the same manner as in the case of the above-mentioned anode.

The separator may be polyethylene, polypropylene, polyvinylidene fluoride or a multilayer film of two or more thereof. The separator may be a polyethylene / polypropylene double-layer separator, It is needless to say that a mixed multilayer film such as a polyethylene / polypropylene / polyethylene three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator and the like can be used.

As the electrolyte to be charged into the lithium secondary battery, a non-aqueous electrolyte or a known solid electrolyte may be used, and a lithium salt dissolved therein may be used.

The solvent of the non-aqueous electrolyte is not particularly limited, but cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; Chain carbonates such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate; Esters such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate and? -Butyrolactone; Ethers such as 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1,2-dioxane and 2-methyltetrahydrofuran; Nitriles such as acetonitrile; Amides such as dimethylformamide and the like can be used. These may be used singly or in combination. Particularly, a mixed solvent of cyclic carbonate and chain carbonate can be preferably used.

As the electrolyte, a gelated polymer electrolyte in which an electrolyte solution is impregnated with a polymer electrolyte such as polyethylene oxide or polyacrylonitrile, or an inorganic solid electrolyte such as LiI or Li ₃ N can be used.

Wherein the lithium salt is selected from the group consisting of LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiSbF ₆ , LiAlO ₄ , LiAlCl ₄ , LiCl, and LiI.

Hereinafter, the embodiment will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

Example  One

(1) Preparation of cathode active material

First, Li (Ni _0.9 Co _0.07 Mn _0.03 ) O ₂ having a concentration gradient was prepared.

Specifically, in order to form a concentration gradient of the core-shell structure, two metal solutions having different mixing ratios of Ni, Co, and Mn may be prepared and used.

The solution of any one solution for the core (Core) formed by using a (Ni _{0. 98} solution of the following composition are consistent with the stoichiometric ratio of Co _{0 .02),} it then slowly added into the reactor first, and then an appropriate amount is turned The other solution can be slowly added using a solution for forming a shell (a solution having a composition conforming to the stoichiometric ratio of Ni _0.7 Co _0.2 Mn _0.1 ).

At this time, using a solution prepared by mixing sodium hydroxide (NaOH) and ammonium hydroxide (NH ₄ OH) as precipitants in a molar ratio of 1.9: 1 to 2.2: 1 (the order of description is sodium hydroxide: ammonium hydroxide) And a solution for forming a shell are put in, respectively, and the concentration gradient is such that in the case of Ni, the concentration gradient from the core portion to the surface portion is up to 90% of the total radius Concentration gradient. At this time, when the concentration of the core portion Ni was taken as 100 mol%, the Ni concentration in the surface portion was gradually decreased to 4 mol%.

For the washing process, 0.001 mol of LiOH and 0.001 mol of LiNO ₃ were dissolved in 75 g of DI water for 3 minutes to prepare a wash liquid. To this washing liquid, a solution of Li (Ni _0.9 Co _0.07 Mn _0.03 ) O ₂ And the mixture was stirred for 10 minutes to prepare a slurry. The slurry was filtered and then dried in a hot air dryer at 250 DEG C for 5 minutes.

 (2) Production of lithium secondary battery

The weight ratio of the cathode active material, the conductive material (Denka black, carbon conductive material), and the binder (PVDF) was 92.5: 3.5: 4 (cathode active material: conductive material: binder) , And uniformly mixed in an N-methyl-2-pyrrolidone solvent to prepare a slurry.

This slurry was evenly applied to an aluminum foil, followed by compression in a roll press and vacuum drying in a 100 vacuum oven for 12 hours to prepare a positive electrode.

A 2032 half-coin cell was prepared according to a conventional method using Li-metal as a counter electrode and 1 mole of LiPF ₆ solution as a liquid electrolyte in a mixed solvent of EC: EMC = 1: 2 as an electrolyte .

Example 2

Except that 0.005 mol of LiOH and 0.005 mol of LiNO ₃ were dissolved in 75 g of distilled water (DI water) in the preparation of the washing liquid, and the cathode active material washed with water in the same manner as in Example 1 And a coin cell.

Example 3

Except that 0.001 mol of LiOH and 0.001 mol of LiNO were dissolved in 100 g of distilled water (DI water) in the preparation of the washing liquid, and the cathode active material washed with water in the same manner as in Example 1 Coin battery was fabricated.

Example 4

The cathode active material washed by the same method as in Example 1 except that 0.005 mol of LiOH and 0.005 mol of LiNO ₃ were dissolved in distilled water (DI water) And 2032 coin batteries were manufactured.

Comparative Example  One

A 2032 coin battery was prepared in the same manner as in Example 1 except that the lithium composite oxide powder obtained in the previous step of the water washing process of Example 1 was used as a cathode active material.

Evaluation example 1

Lithium remaining on the surface of each of the cathode active materials of Examples 1 to 4 and Comparative Example 1 was measured. For each cell (2032 coin cell) of Examples 1 to 4 and Comparative Example 1, an initial capacity of 0.2 C was evaluated. The results are shown in Table 1 and Fig. 1 below.

division Residual lithium (LiOH / Li ₂ CO _3, unit ppm) Initial capacity (0.2C) Comparative Example 1 12,685 / 6,356 202.1 Example 1 4,268 / 2,543 211.5 Example 2 4,125 / 2,385 212.4 Example 3 3,214 / 2,235 211.2 Example 4 3,117 / 1,956 210.7

As shown in Table 1 and FIG. 1, residual lithium in the washed positive electrode active material (Examples 1 to 4) was remarkably reduced as compared with the case where the battery was not rinsed at all (Comparative Example 1) The initial capacity is also increased.

Specifically, the cathode active material (i.e., Li (Ni _0.9 Co _0.07 Mn _0.03 ) O ₂ having a concentration gradient) is 97.54 g / mole and 100 g is about 1.025 mol.

Considering this fact, when the LiOH and LiNO ₃ in the wash water solution are 0.001 mole to 0.005 mole per 1 mole of the cathode active material to be water-treated (ranges including all of Examples 1 to 4), the residual lithium It is possible to evaluate the effect of improving the initial capacity of the battery.

Evaluation Example 2: Li / Me molar ratio

Table 2 below shows the Li / Me molar ratio of the cathode active material subjected to the washing treatment in Examples 1 to 4 and the cathode active material of Comparative Example 1,

In Table 2, it can be seen that the Li / Me ratio of the cathode active material (Examples 1 to 4) treated with water more than that of the cathode active material (Comparative Example 1) not washed with water is low, have.

On the other hand, when comparing Examples 1 to 4, and washing at higher within the molar concentration of the LiOH and LiNO ₃ (Example 2 and 4), Li / Me ratio is reduced to be viewed, and washing in LiOH and LiNO ₃ to If the molar concentration is excessively high, lithium in the cathode active material is likely to be removed. Therefore, it is estimated that it is necessary to maintain the molar concentration of LiOH and LiNO _{3 in} the wash liquid at least as high as in Examples 2 and 4.

division Li / Me molar ratio Comparative Example 1 1.08 Example 1 1.01 Example 2 0.999 Example 3 1.002 Example 4 0.998

Evaluation Example 3: SEM photograph

When comparing the SEM photograph (FIG. 2) of the cathode active material of Comparative Example 1 and the SEM photograph (FIG. 3) of the cathode active material of Example 2, it is confirmed that there is no difference in appearance according to the water washing treatment. Thus, it can be seen that the water washing treatment of the examples does not affect the external shape of the cathode active material.

4 is a FIB EDX analysis photograph of the cathode active material of Example 2 of the present invention. By observing FIG. 4, it can be seen that the compositional change with respect to the concentration gradient of the core and shell of metals such as Ni, Co, Mn, and Zr after firing (there is a difference of about 2% in Ni standard).

While the present invention has been described in connection with certain exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (17)

Preparing a lithium composite oxide comprising Ni, Co, and Mn; And
And washing the lithium composite oxide with water,
Would have, lithium hydroxide (LiOH), lithium nitrate (LiNO _3), and can, comprising a solvent, is performed using the amount of a tax,; the step of washing the lithium composite oxide
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
The content of lithium hydroxide (LiOH)
Wherein the lithium complex oxide is 0.0001 to 0.01 mole based on 1 mole of the lithium composite oxide.
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
The molar ratio of lithium hydroxide (LiOH): lithium nitrate (LiNO ₃ )
1: 0.1 to 1: 10.
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
The content of the solvent in the washing liquid is,
And 50 to 200 parts by weight based on 100 parts by weight of the lithium composite oxide.
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
The total composition of the lithium composite oxide is,
A positive electrode active material for a lithium secondary battery, comprising:
[Chemical Formula 1]
Li _x Ni _a Co _b Mn _c M _{d d} O ₂
X is in the range of 0.90? X? 0.7, 0.7? A <1, 0? B? 0.3, 0? c? 0.3, 0 <d <0.01, and a + b + c + d = 1.)
6. The method of claim 5,
In the lithium composite oxide,
Is a secondary particle in which two or more particles having different values of a, b, and c in the above formula (1)
(Method for producing positive electrode active material for lithium secondary battery).
6. The method of claim 5,
In the lithium composite oxide,
Wherein a concentration gradient of all or some of the elements of at least one of Ni, Mn, and Co is present.
(Method for producing positive electrode active material for lithium secondary battery).
8. The method of claim 7,
Preparing a lithium composite oxide comprising Ni, Co, and Mn,
Preparing an active material precursor comprising Ni, Co, and Mn by coprecipitation; And
And firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide.
(Method for producing positive electrode active material for lithium secondary battery).
9. The method of claim 8,
Wherein the mixture of the active material precursor and the lithium source material further comprises a doping raw material,
Wherein the doping source material is a compound containing at least one element selected from the group consisting of Zr, Ti, and Al, or a mixture of the above compounds.
(Method for producing positive electrode active material for lithium secondary battery).
9. The method of claim 8,
Firing a mixture of the active material precursor and the lithium source material to obtain a lithium composite oxide; Since the,
And forming a coating layer on the surface of the lithium composite oxide,
Wherein said coating layer comprises a compound comprising at least one element selected from the group consisting of B, Al, P and Si, or a mixture of said compounds.
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
Washing the lithium composite oxide with water,
Adding the lithium composite oxide to the washing solution and stirring to prepare a slurry; And
And filtering the slurry to obtain a washed lithium composite oxide.
(Method for producing positive electrode active material for lithium secondary battery).
12. The method of claim 11,
Adding the lithium composite oxide to the washing liquid and stirring to prepare a slurry,
Lt; RTI ID = 0.0 &gt; 1 &lt; / RTI &gt;
(Method for producing positive electrode active material for lithium secondary battery).
12. The method of claim 11,
Filtering the slurry to obtain a washed lithium composite oxide; Since the,
And drying the washed lithium composite oxide.
(Method for producing positive electrode active material for lithium secondary battery).
14. The method of claim 13,
Drying the washed lithium composite oxide,
Lt; RTI ID = 0.0 &gt; 80 C &lt; / RTI &gt; to 300 C,
(Method for producing positive electrode active material for lithium secondary battery).
14. The method of claim 13,
And drying the washed lithium composite oxide,
Lt; RTI ID = 0.0 &gt; 1 &lt; / RTI &gt;
(Method for producing positive electrode active material for lithium secondary battery).
The method according to claim 1,
Washing the lithium composite oxide with water; Since the,
And heat-treating the washed lithium complex oxide.
(Method for producing positive electrode active material for lithium secondary battery).
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