KR101759445B1 - Cathode active materials with dopant for reducing remaining lithium and lithiumsecondary battery using the same, and preparation method thereof - Google Patents

Abstract

The present invention relates to a positive electrode active material in which a polymer material (F) containing F is added or coated with sugar to reduce residual lithium ions and a method for producing the same. More particularly, the present invention relates to a cathode active material, A second step of preparing a mixture by mixing a polymer material with the cathode active material; And a third step of heating the mixture to produce a cathode active material to which PCTFE is added. The method of manufacturing a cathode active material to which PCTFE is added, and a first step of preparing a cathode active material; A second step of preparing sugar having a specific weight percentage relative to the cathode active material; A third step of dissolving the sugar in a solvent to prepare a sugar solution; A fourth step of mixing the sugar solution and the cathode active material to prepare a mixture; And after drying the mixture. And a fifth step of heating the mixture to prepare a cathode active material coated with sugar. The present invention also relates to a method for producing a sugar-coated cathode active material.

Description

[0001] The present invention relates to a positive electrode active material to which a dopant is added for reducing residual lithium, a method for producing the positive electrode active material, and a lithium secondary battery using the lithium secondary battery,

The present invention relates to a cathode active material doped with a dopant, a method for producing the cathode active material, and a lithium secondary battery. More specifically, the present invention relates to a positive electrode active material in which a high molecular weight material (F) is added or coated with sugar to reduce residual lithium and a method for producing the same.

Recently, miniaturization of electronic devices has been diversified into mobile phones, notebook computers (PCs), and portable personal digital assistants (PDAs), and the interest in energy storage technology has been increasing.

In addition, in the case of batteries used in hybrid vehicles (HEV) and electric vehicles (EV), not only high capacity and high output, but also stability are a big problem. As application fields expand, research and development on storage technologies are being actively carried out. In this respect, there is a growing interest in the development of secondary batteries capable of charging and discharging.

The secondary battery is composed of a positive electrode, a negative electrode, and an electrolyte, and the ratio of the positive electrode is the most important. The cathode material is a cathode active material and generally has a high energy density during charging and discharging, and the structure should not be destroyed by intercalation or desorption of reversible lithium ions. In addition, the electrical conductivity should be high, and the chemical stability of the organic solvent used as the electrolyte should be high. It should be a material that has low manufacturing cost and minimizes environmental pollution problems.

Examples of the positive electrode active material of such a lithium ion secondary battery include lithium nickel oxide (LiNiO ₂ ), lithium cobalt oxide (LiCoO ₂ ), lithium manganese oxide (LiMnO ₂ ), and the like, which are layered compounds capable of intercalating and deintercalating lithium ions. Lithium nickel oxide (LiNiO ₂ ) has a high electric capacity, but it has not been put to practical use due to problems such as cycle characteristics and stability during charging and discharging. In addition, lithium cobalt oxide (LiCoO ₂ ) is advantageous in terms of cycle life and rate capability as well as capacity, and is easy to synthesize. However, since cobalt is expensive and harmful to human body, thermal instability And the like.

In addition, the cathode active material is prepared by mixing lithium hydroxide and a precursor with heat treatment. After the heat treatment, residual LiOH and Li ₂ CO ₃ that are not involved in the cathode active material reaction exist.

Such residual LiOH increases the pH of the slurry in the process of producing the slurry, causing the solidification of the slurry to cause problems in the production of the electrode plate. In addition, residual Li ₂ CO ₃ increases cell swelling and not only reduces the cycle, but also causes the battery to swell.

Therefore, a method for reducing the concentration of such residual lithium ions has been required.

Korea Patent Publication No. 2014-0001720 Korean Patent Publication No. 2013-0030479

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art. Accordingly, it is an object of the present invention to provide a positive electrode active material coated with a polymer material (PCTFE) (PCTFE) or the addition of sugar, the surface cohesion is controlled and the surface roughness is also decreased, thereby increasing the surface area, decreasing the charge transfer resistance and increasing the lithium diffusion (PCTFE) or a positive electrode active material to which sugar is added, and a method of manufacturing the same.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

A first object of the present invention is to provide a method for manufacturing a positive electrode active material, A second step of preparing a mixture by mixing a polymer material with the cathode active material; And a third step of heating the mixture to produce a cathode active material doped with a dopant. The cathode active material may be doped with a dopant.

Further, the polymer material is a polymer material including F, and may be characterized by being in the form of a fillet.

In the third step, the mixture is heated to 300 to 500 ° C at a heating rate of 3 to 8 ° C / min, and then maintained for 8 to 10 hours.

The F-containing polymer material may be mixed in an amount of 0.09 to 1.5 wt%.

A second object of the present invention is to provide a method for manufacturing a positive electrode active material, A second step of preparing sugar having a specific weight percentage relative to the cathode active material; A third step of dissolving the sugar in a solvent to prepare a sugar solution; A fourth step of mixing the sugar solution and the cathode active material to prepare a mixture; And after drying the mixture. And a fifth step of preparing a cathode active material doped with a dopant by heating the cathode active material.

In addition, in the second step, the ratio of the sugar may be 0.9 to 6.0 wt% of the cathode active material.

In the third step, the solvent may be N-methyl pyrrolidone.

Further, in the fourth step, stirring may be performed at 50 to 70 DEG C for 5 to 7 hours at 300 to 500 RPM.

In the fifth step, the mixture is filtered and then dried in a vacuum oven at 100 to 120 ° C for 20 to 28 hours.

After drying, the substrate is heated to 500 to 700 ° C at a temperature raising rate of 3 to 8 ° C / min, and then maintained for 4 to 6 hours.

According to one embodiment of the present invention, a polymer material (F) -containing F material added as a dopant material (PCTFE) or a sugar-coated positive electrode material reduces the concentration of residual lithium ions, Or the surface agglomeration phenomenon is controlled from the addition of sugar and the surface roughness is also decreased to increase the surface area, the charge transfer resistance is decreased, and the lithium diffusion is increased, so that the charge / Can be increased.

It should be understood, however, that the effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those skilled in the art to which the present invention belongs It will be possible.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description, serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
1 is a flow chart of a method for producing a cathode active material to which PCTFE is added according to an embodiment of the present invention,
2 is a graph showing the relationship between the residual Li ₂ CO ₃ and LiOH of the positive electrode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and the positive electrode active material according to Comparative Example,
FIG. 3 is a photograph of a particle shape observed by a scanning electron microscope of a cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example,
FIG. 4 is a graph showing resistance analysis of a cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example,
5 is a table showing charge transfer resistance analysis results of the positive electrode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and the positive electrode active material according to Comparative Example,
6 is a graph showing the initial charge / discharge characteristics of the positive electrode active material to which PCTFE is added and the positive electrode active material according to the comparative example according to the first and second embodiments of the present invention,
7 is a graph showing the relationship between the initial charge / discharge capacity of the positive electrode active material to which PCTFE is added and the positive electrode active material according to the comparative example according to Examples 1 and 2 of the present invention,
FIG. 8 is a flow chart of a method for manufacturing a sugar-coated cathode active material according to an embodiment of the present invention;
FIG. 9 is a graph comparing the residual Li ₂ CO ₃ and LiOH values of the positive electrode active material coated with sugar according to Examples 1, 2, and 3 of the present invention and the positive electrode active material according to Comparative Example,
FIG. 10 is a graph showing particle photographs observed with a scanning electron microscope of a sugar-coated cathode active material according to Examples 1, 2, and 3 of the present invention and a cathode active material according to a comparative example;
11 is a graph showing resistance analysis of a sugar-coated positive electrode active material according to Examples 1, 2, and 3 of the present invention and a positive electrode active material according to a comparative example,
12 is a table showing the charge transfer resistance analysis of the positive electrode active material coated with the sugar according to Examples 1, 2, and 3 of the present invention and the positive active material according to the comparative example,
13 is a graph showing the initial charging / discharging characteristics of the cathode active material coated with sugar according to Examples 1, 2, and 3 of the present invention and the cathode active material according to the comparative example,
FIG. 14 is a table showing the initial charge / discharge capacity and coulon efficiency of the positive electrode active material coated with the sugar according to Examples 1, 2, and 3 of the present invention and the positive electrode active material according to the comparative example.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween.

Although the terms first, second, etc. have been used in various embodiments of the present disclosure to describe various components, these components should not be limited by these terms. These terms have only been used to distinguish one component from another. The embodiments described and exemplified herein also include their complementary embodiments.

The terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms "comprises" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other elements.

In describing the specific embodiments below, various specific details have been set forth in order to explain the invention in greater detail and to assist in understanding it. However, it will be appreciated by those skilled in the art that the present invention may be understood by those skilled in the art without departing from such specific details. In some instances, it should be noted that portions of the invention that are not commonly known in the description of the invention and are not significantly related to the invention do not describe confusing reasons to explain the present invention.

≪ Configuration and Manufacturing Method of Cathode Active Material to which Polymer Material Containing F (PCTFE) is Added >

Hereinafter, a configuration and a manufacturing method of a cathode active material to which a polymer material (PCTFE) containing F is added according to an embodiment of the present invention will be described. 1 is a flowchart illustrating a method of manufacturing a cathode active material to which PCTFE is added according to an embodiment of the present invention.

First, a cathode active material to which a high molecular substance (PCTFE) containing F is to be added is prepared (S1). The cathode active material to which the present invention is applied is not limited. As a specific example, a metal aqueous solution is prepared from nickel (Ni), cobalt (Co) and manganese (Mn) using distilled water as a solvent, and sodium carbonate is used as a precipitant and ammonia water is used as a chelating agent to precipitate the precursor. Then, the precipitated precursor is filtered and washed, dried, mixed with lithium hydroxide in the precursor, heated at an elevated temperature, and then naturally cooled to produce a cathode active material. This is only a concrete example, and the composition and manufacturing method of the cathode active material to which the F-containing polymer material (PCTFE) is to be added is not limited to this.

Then, the prepared cathode active material is mixed with a polymer material to prepare a mixture (S2). Such a polymer material has a fillet shape and corresponds to a polymer material (FT-containing polymer).

In addition, the polymer material including F is mixed with 0.09 to 1.5 wt% of the weight of the cathode active material.

Then, the mixture is heated to produce a cathode active material to which a high molecular substance (PCTFE) containing F is added. More specifically, the powdery mixture is heated to 300 to 500 DEG C at a heating rate of 3 to 8 DEG C / min, and then maintained for 8 to 10 hours.

≪ Experimental data of a cathode active material to which a polymer substance (PCTFE) containing F is added >

Hereinafter, experimental data on the cathode active material to which the F-containing polymer material (PCTFE) according to the present invention is added will be described. First, Embodiment 1, Embodiment 2, and Comparative Example of the present invention applied to the experiment will be described.

Comparative Example (pristine CSG131) is a comparative example to be as a positive electrode active material is not added to the _{PCTFE, Ni 0.8031 Co 0.1168 Mn 0.0801} (OH) After preparing a precursor of a _second, after heating temperature was raised by mixing lithium hydroxide and natural cooling was added to PCTFE To prepare a cathode active material.

In Example 1 (0.1 wt% of PCTFE), 10 g of the cathode active material of the comparative example was mixed with a PCTFE in the form of a fillet at a ratio of 0.1 wt%, the temperature of the mixed powder was raised to 350 ° C. at a rate of 5 ° C. per minute, Lt; / RTI >

In Example 2 (PCTFE 1 wt%), 10 g of the cathode active material of the comparative example was mixed with a PCTFE in the form of a fillet at a ratio of 1 wt%, the temperature of the mixed powder was raised to 350 캜 at a rate of 5 캜 per minute, Lt; / RTI >

FIG. 2 is a table showing the residual Li ₂ CO ₃ and LiOH contrast of the cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and the cathode active material according to Comparative Example. As in DP 1,2, when 0.1 and 1 wt% of F-containing polymer were added, LiOH was decreased to 1,780 and 1,664 ppm, respectively, compared to the comparative examples, 2002 and 2118 ppm, respectively. However, Li ₂ CO ₃ increased by 4,007 and 448 ppm at 7,808 and 4,249 ppm, respectively. Although the amount of Li ₂ CO ₃ is slightly increased, it can be seen that adding 1 wt% of PCTFE is an effective additive because of the reduction of LiOH by 2118 ppm.

FIG. 3 is a graph showing the particle shape of a cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example, which were observed with an F- electron Scanning Electron Microscope (FE-SEM) FIG. As shown in FIG. 3, it can be seen that the cathode active material of the comparative example having a spherical shape has a diameter of about 10 탆 and primary particles having a diameter of about 200 to 300 nm are aggregated . At the low magnification of 10,000, we could not confirm the difference on the surface, but we could confirm the difference of the first investor at the high magnification of 25,000 times and 100,000 times. It was confirmed that rough protrusions were formed on the surface of the primary particles of the comparative positive electrode active material according to the amounts of Examples 1 and 2 to which PCTFE was added. It is judged that this is a protrusion formed by wrapping the surface of the primary particle of PCTFE.

FIG. 4 is a graph showing resistance analysis of a cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example. 5 is a graph showing the charge transfer resistance analysis table of the positive electrode active material to which PCTFE is added and the positive electrode active material according to the comparative example according to Examples 1 and 2 of the present invention.

That is, FIG. 4 is a graph showing the results of measurement of the cathode active materials of Examples 1 and 2, in which 0.1 wt% and 1 wt% of PCTFE, which is a polymeric substance containing F, was added to the cathode active material according to the comparative example in a frequency range of 0.01 Hz to 10,000 Hz A Nyquist plot of a cathode active material is shown. Both plots have one semicircle in the high frequency region and a steep straight line in the low frequency region. The diameter of the semicircle in the high frequency region represents the charge transfer resistance (R _ct ) at the interface between the electrode and the electrolyte. The Rct values of the cathode active materials R and C added with 0.1 and 1 wt% of polymeric substance (PCTFE) containing F were 269.6 and 321.5?, Respectively, which were 1.5 and 53.4? It was confirmed that the charge transfer resistance was increased by adding a polymer material.

6 is a graph showing initial charging / discharging characteristics of a cathode active material to which PCTFE is added according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example. Discharge capacity and Coulomb efficiency of the cathode active material with PCTFE added and the cathode active material according to the comparative example.

That is, FIG. 6 is a graph showing that the cathode active materials of Examples 1 and 2, in which 0.1 wt% and 1 wt% of PCTFE, which is a polymer material containing F, were added to the cathode active materials of Comparative Examples and Comparative Examples, V shown in FIG. The charge capacities of the cathode active materials of Examples 1 and 2, in which PCTFE was added at 0.1 and 1 wt%, were 200.86 and 199.54 mAh / g, respectively, which were 8.38 and 7.06 mAh / g, respectively, and discharge capacities were 182.65 and 190.82 mAh / g, Which is 19.61 and 27.78 mAh / g, as compared with the comparative example. Also, as shown in FIG. 7, it was confirmed that the coulombic efficiency was increased by 6.23 and 10.93%, respectively, as compared with the comparative example. This shows that the addition of PCTFE reduced the amount of residual lithium and thus exhibited effective electrochemical properties.

<Composition and Manufacturing Method of Cationic Active Material Coated with Sugar>

Hereinafter, the structure and manufacturing method of the sugar-coated cathode active material according to one embodiment of the present invention will be described. 8 is a flowchart illustrating a method of manufacturing a cathode active material coated with sugar according to an embodiment of the present invention.

First, a cathode active material to be coated with sugar is prepared (S10). The cathode active material to which the present invention is applied is not limited. As a specific example, a metal aqueous solution is prepared from nickel (Ni), cobalt (Co) and manganese (Mn) using distilled water as a solvent, and sodium carbonate is used as a precipitant and ammonia water is used as a chelating agent to precipitate the precursor. Then, the precipitated precursor is filtered and washed, dried, mixed with lithium hydroxide in the precursor, heated at an elevated temperature, and then naturally cooled to produce a cathode active material. This is merely a specific example, and the composition and manufacturing method of the cathode active material to be coated with sugar are not limited thereto.

Then, a sugar having a specific weight percentage with respect to the prepared cathode active material is prepared (S20). The proportion of such sugar corresponds to about 0.9 to 5.5 wt% of the cathode active material.

Then, sugar is dissolved in a solvent to prepare a sugar solution (S30). N-methylpyrrolidone (NMP) can be applied as a solvent.

Then, the prepared cathode active material is mixed and stirred to prepare a mixture (S40). This step is preferably carried out at 50 to 70 ° C for 5 to 7 hours at 300 to 500 RPM.

Then, after drying the mixture. Followed by heating to produce a positive electrode active material coated with sugar (S50). More specifically, the mixture is filtered and then dried in a vacuum oven at 100-120 &lt; 0 &gt; C for 20-28 hours. After drying, the mixture is heated to a temperature of 500 to 700 ° C. at a temperature raising rate of 3 to 8 ° C./min and maintained for 4 to 6 hours to produce a sugar-coated cathode active material according to an embodiment of the present invention.

<Experimental Data of Cationic Active Material Coated with Sugar>

Hereinafter, experimental data on the sugar-coated cathode active material according to the present invention will be described. First, Example 1, Example 2, Example 3 and Comparative Example of the present invention applied to the experiment will be described.

Comparative Example (pristine CSG131) is a positive electrode active material is not added to the _{PCTFE, Ni 0.8031 Co 0.1168 Mn 0.0801} (OH) After preparing a precursor of a _second, after heating temperature was raised by mixing the lithium hydroxide to cool naturally the positive electrode active material according to Comparative Example .

In Example 1 (1 wt% of Sugar), sugar was prepared at a ratio of 1 wt% based on 10 g of the cathode active material of the comparative example, and the sugar was dissolved in N-methylpyrrolidone at 400 RPM and 60 ° C for 1 hour. Then, the positive electrode active material according to Comparative Example was added to the solution in which the sugar was dissolved, and the mixture was stirred at 400 RPM and 60 ° C for 6 hours. The stirred solution was filtered and then dried in a vacuum oven at 110 ° C for 24 hours. The dried powder was heated at a rate of 5 ° C per minute to 350 ° C and maintained for 1 hour.

In Example 2 (Sugar 3 wt%), sugar was prepared at a ratio of 3 wt% with respect to 10 g of the cathode active material of the comparative example, and the sugar was dissolved in N-methylpyrrolidone at 400 RPM and 60 ° C for 1 hour. Then, the positive electrode active material according to Comparative Example was added to the solution in which the sugar was dissolved, and the mixture was stirred at 400 RPM and 60 ° C for 6 hours. The stirred solution was filtered and then dried in a vacuum oven at 110 ° C for 24 hours. The dried powder was heated at a rate of 5 ° C per minute to 350 ° C and maintained for 1 hour.

In Example 3 (Sugar 5 wt%), sugar was prepared at a ratio of 5 wt% based on 10 g of the cathode active material of the comparative example, and the sugar was dissolved in N-methylpyrrolidone at 400 RPM and 60 ° C for 1 hour. Then, the positive electrode active material according to Comparative Example was added to the solution in which the sugar was dissolved, and the mixture was stirred at 400 RPM and 60 ° C for 6 hours. The stirred solution was filtered and then dried in a vacuum oven at 110 ° C for 24 hours. The dried powder was heated at a rate of 5 ° C per minute to 350 ° C and maintained for 1 hour.

FIG. 9 is a table showing the residual Li ₂ CO ₃ and LiOH of the positive electrode active material coated with the sugar according to Examples 1, 2, and 3 of the present invention and the positive electrode active material according to the comparative example. That is, FIG. 9 is a graph showing the results of measurements of LiOH and Li ₂ CO ₃ of the cathode active material according to Examples 1, 2, and 3 in which the cathode active material according to the comparative example in which no sugar is coated and 1, 3, and 5 wt% The results are as follows. When 1, 3, and 5 wt% of sugar were coated, the LiOH was decreased to 1,383, 1,921, and 2,156 ppm, respectively, by 1,393, 1861, and 1626 ppn, respectively. However, in Li ₂ CO ₃ , it was 6,351, 6,971, and 7,148 ppm, which was increased by 2,550, 3,170, and 3347 ppm compared to CSG131.

FIG. 10 is a photograph of particles observed with a scanning electron microscope of a sugar-coated cathode active material according to Examples 1, 2, and 3 of the present invention and a cathode active material according to a comparative example. That is, FIG. 10 shows an image of a field emission scanning microscope of a cathode active material according to Examples 1, 2, and 3 in which a cathode active material according to a comparative example and 1, 3, and 5 wt% of sugar were added, respectively. The cathode active material having a spherical shape has a diameter of about 10 mu m, and primary particles having a diameter of about 200 to 300 nm are aggregated. At the low magnification of 10,000 times, we could not confirm the difference on the surface, but we can confirm the difference of the first investor at the high magnification of 25,000 times and 100,000 times. It was confirmed that carbon was coated on the primary particles of the cathode active material according to the amount of added sugar.

FIG. 11 is a graph showing resistance analysis of a sugar-coated cathode active material according to Examples 1 and 2 of the present invention and a cathode active material according to a comparative example. 12 is a graph showing a charge transfer resistance analysis table of a sugar-coated positive electrode active material according to Examples 1, 2, and 3 of the present invention and a positive electrode active material according to a comparative example.

That is, FIG. 11 is a graph showing the results of the Nyquist plot of the cathode active material measured in the frequency range of 0.01 Hz to 10,000 Hz for Examples 1, 2, and 3 coated with 1, 3, and 5 wt% FIG. Both plots have one semicircle in the high frequency region and a steep straight line in the low frequency region. The diameter of the semicircle in the high frequency region represents the charge transfer resistance (R _ct ) at the interface between the electrode and the electrolyte. The Rct values of the cathode active materials according to Examples 1, 2, and 3 coated with 1, 3, and 5 wt% of sugar were 309, 296.4, and 192.5Ω, respectively, and Example 3 in which 5 wt% 75.6 Ω compared to the conventional one.

FIG. 13 is a graph showing initial charge / discharge characteristics of a cathode active material coated with sugar according to Examples 1, 2, and 3 of the present invention and a cathode active material according to a comparative example. FIG. 2 is a graph showing the initial charge / discharge capacity and Coulomb efficiency of a cathode active material coated with a sugar according to Comparative Examples 2 and 3 and a cathode active material according to a comparative example.

That is, FIGS. 13 and 14 show the initial charge / discharge characteristics, the capacity and the coulombic efficiency of the cathode active material according to the comparative example and the cathode active materials according to Examples 1, 2 and 3 to which 1, 3 and 5 wt% . The initial charge capacities of the cathode active materials according to Examples 1, 2 and 3 to which 1, 3 and 5 wt% of the sugar were applied were 216.56, 216.33 and 218.99 mAh / g, respectively, and the initial discharge capacities were 188.42, 184.01 and 191.75 mAh / g It was confirmed that the initial charge / discharge capacity of the cathode active material according to the comparative example was increased by about 24 to 2 mAh / g compared with 192.48 and 163.04 mAh / g. Also, the Coulomb efficiency was increased from 84.70% to 85% to 87%, which was about 2%.

Claims (15)

A first step of preparing a cathode active material;
A second step of preparing sugar having 0.9 to 6.0 wt% with respect to the cathode active material;
A third step of dissolving the sugar in N-methylpyrrolidone to prepare a sugar solution;
Mixing the sugar solution with the cathode active material and stirring the mixture at 50 to 70 ° C for 5 to 7 hours at 300 to 500 rpm; And
The mixture was filtered and dried in a vacuum oven at 100 to 120 ° C for 20 to 28 hours, dried and heated to a temperature of 500 to 700 ° C at a heating rate of 3 to 8 ° C / min, and then maintained for 4 to 6 hours And a fifth step of adding the dopant to the cathode active material.
delete delete delete delete delete A positive electrode active material to which a dopant is added, which is produced by the production method according to claim 1.
A lithium secondary battery comprising a cathode active material for a lithium secondary battery, a cathode, and an electrolyte prepared by the manufacturing method according to claim 1. delete delete delete delete delete delete delete

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