KR102233907B1 - Crucible and crucible assembly for preparing cathode active material - Google Patents

Abstract

The present invention provides a crucible assembly for manufacturing a positive electrode active material. The present invention is a first crucible having an open top and a predetermined inner space, and a second crucible disposed below the first crucible and having a cut groove having a preset open area disposed at the upper end of each sidewall Includes.

Description

Crucible and crucible assembly for preparing cathode active material {Crucible and crucible assembly for preparing cathode active material}

The present invention relates to a crucible and a crucible assembly for manufacturing a positive electrode active material.

Since the lithium secondary battery was commercialized by Sony in 1991, demand has been rapidly increasing in various fields ranging from small home appliances to mid- to large-sized electric vehicles and energy storage systems. In particular, low-cost, high-energy cathode materials are essential for mid- to large-sized electric vehicles and energy storage systems, and cobalt, which is the main raw _{material of single crystal LiCoO 2 (LCO), which is a cathode active material currently commercially available, is expensive.}

_{So, LiNi x} Co _y Mn _z O ₂ (NCM, x+y+z=1) and LiNi _x Co _y Al _z O, in which a part of Co is substituted with another transition metal instead of LCO as a positive electrode active material for mid- to large-sized secondary batteries. ₂ (NCA, x+y+z=1), a Ni-based cathode active material is used, and these NCM and NCA-based cathode active materials have the advantage that the price of nickel as a raw material is inexpensive and has a high reversible capacity. In particular, in terms of high capacity, NCM and NCA with a molar ratio of Ni of 50 mol% or more are attracting attention. In general, such a Ni-based positive electrode active material is prepared by mixing a transition metal compound precursor synthesized by a co-precipitation method with a lithium source and then synthesizing it in a solid state. However, the Ni-based cathode material synthesized in this way exists in the form of secondary particles in which small primary particles are aggregated, and there is a problem in that micro-crack occurs inside the secondary particles during a long-term charging/discharging process. The microcracks induce a side reaction between the new interface of the positive electrode active material and the electrolyte, and as a result, deterioration of battery performance such as deterioration of stability due to gas generation and deterioration of battery performance due to depletion of electrolyte is induced. In addition, an increase in electrode density (>3.3g/cc) is required to realize a high energy density, which causes the collapse of secondary particles, causing electrolyte depletion due to side reactions with the electrolyte, leading to a sharp decline in initial lifespan. Consequently, it means that the Ni-based cathode active material in the form of secondary particles synthesized by the conventional coprecipitation method cannot achieve high energy density.

In order to solve the problems of the above-described secondary particle type Ni-based positive electrode active material, studies on single-particle type Ni-based positive electrode active material have recently been conducted. The single crystal type Ni-based cathode active material does not cause particle collapse when the electrode density is increased (> 3.3g/cc) to realize high energy density, so it can realize excellent electrochemical performance. However, such a single crystal type Ni-based positive electrode active material has a problem in that battery stability is deteriorated due to structural and/or thermal instability due to ^{unstable Ni 3 +} and Ni ^{4 + ions during electrochemical evaluation.} Therefore, in order to develop a high-energy lithium secondary battery, there is still a need for a technology for stabilizing unstable Ni ions in a single crystal Ni-based positive electrode active material.

An object of the present invention is to provide a crucible and a crucible assembly capable of manufacturing a positive electrode active material having a single particle shape and having a high energy density. In addition, an object of the present invention is to provide a crucible and a crucible assembly capable of manufacturing a Ni-based positive electrode active material having an extended service life. However, these problems are exemplary, and the scope of the present invention is not limited thereby.

One side of the present invention includes a first crucible having an open upper portion and a predetermined inner space, and a cut groove disposed under the first crucible and having a predetermined open area disposed at the upper end of each sidewall. Eggplant provides a crucible assembly for manufacturing a positive electrode active material including a second crucible.

In addition, the open area of the cut groove satisfies the following equation.

[Equation]

A _O : Open area of the incision groove, A _T : Area of the side wall of one second crucible

In addition, the incision groove may be disposed above the center of the height of the second crucible.

In addition, the second crucible may be disposed so that the sidewalls face each other, and a plurality of cutout grooves may be provided, and may be disposed to overlap each of the sidewalls.

In addition, at least one of the first crucible and the second crucible may be formed of a compound represented by the following formula.

[Chemical Formula]

xAl ₂ O ₃ yMgO zSiO ₂ (0.9<x<1, 0<y<0.1, 0<z<0.1, x+y+z=1)

In addition, a plurality of second crucibles may be provided, and may be stacked under the first crucible in a height direction.

Another aspect of the present invention is a crucible for manufacturing a positive electrode active material having a predetermined internal space by a bottom and a side wall, comprising a cut groove having a set open area disposed on the upper end of the side wall, and the open area of the cut groove Provides a crucible for manufacturing a cathode active material according to the following equation.

[Equation]

A _O : Open area of the incision groove, A _T : Area of one side wall

In addition, the crucible may be formed of a compound represented by the following formula.

[Chemical Formula]

xAl ₂ O ₃ yMgO zSiO ₂ (0.9<x<1, 0<y<0.1, 0<z<0.1, x+y+z=1)

Other aspects, features, and advantages other than those described above will become apparent from the detailed contents, claims, and drawings for carrying out the following invention.

The crucible and crucible assembly for manufacturing a cathode active material according to the present invention can synthesize a single particle cathode active material. Since the incision groove is provided on the sidewall of the crucible, heat of a high temperature can be sufficiently introduced into the inner space of the crucible, so that a single particle of the positive electrode active material can be synthesized.

The crucible and crucible assembly for manufacturing a cathode active material according to the present invention can mass-produce a single-particle cathode active material. The crucible may be stacked in a height direction to form a crucible assembly, and a single-particle positive electrode active material may be mass-produced from the stacked crucible. In particular, since the open area of the cut groove can be minimized, the amount of the positive electrode active material that can be produced in each crucible can be maximized.

The crucible and crucible assembly for manufacturing a positive electrode active material according to the present invention can produce a positive electrode active material with reduced fines of less than 1 μm. By increasing the composition of Al ₂ O _{3 in} the crucible, it is possible to minimize the amount of fine powder in the synthesized positive electrode active material, thereby improving the life stability of the positive electrode active material. Of course, the scope of the present invention is not limited by these effects.

1 is a perspective view showing a crucible assembly for manufacturing a positive electrode active material according to an embodiment of the present invention.
2 is a perspective view showing a crucible according to an embodiment of the present invention.
3 is a view showing one side wall of the crucible of FIG. 2.
FIG. 4 is a diagram illustrating an apparatus for manufacturing a cathode active material using the crucible for manufacturing the cathode active material of FIG. 1.
5 is a SEM photograph of the positive electrode active material of Examples 1 to 5.
6 is a SEM photograph of the positive electrode active material of Comparative Examples 1 to 5.
7 is a SEM photograph of the positive electrode active material of Example 6, Comparative Example 6-1, and Comparative Example 6-2.
8 is an SEM photograph of the positive electrode active material of Example 7, Comparative Example 7-1, and Comparative Example 7-2.
9 is a SEM photograph of the positive electrode active material of Example 8, Comparative Example 8-1, and Comparative Example 8-2.
10 is a graph showing the particle size distribution of cathode active materials of Examples 9-1, 9-2, and Comparative Example 9.
11 is a graph of life retention rates for the half cells of Example 9-1, Example 9-2, and Comparative Example 9. FIG.
12 is a graph of life retention rates for the half cells of Examples 10-1, 10-2, and Comparative Example 10;
13 is a graph of life retention rates for the half cells of Example 11-1, Example 11-2, and Comparative Example 11. FIG.
14 is a graph of life retention rates for half cells of Example 12-1, Example 12-2, and Comparative Example 12. FIG.
Fig. 15 is a schematic diagram of a lithium battery according to an exemplary embodiment.

Hereinafter, various embodiments of the present disclosure will be described in connection with the accompanying drawings. Various embodiments of the present disclosure may be subjected to various changes and may have various embodiments, and specific embodiments are illustrated in the drawings and related detailed descriptions are described. However, this is not intended to limit the various embodiments of the present disclosure to a specific embodiment, and it should be understood that all changes and/or equivalents or substitutes included in the spirit and scope of the various embodiments of the present disclosure are included. In connection with the description of the drawings, similar reference numerals have been used for similar elements.

Expressions such as "include" or "may include" that may be used in various embodiments of the present disclosure indicate the existence of a corresponding function, operation, or component disclosed, and additional one or more functions, operations, or It does not limit the components, etc. In addition, in various embodiments of the present disclosure, terms such as "comprises" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, It is to be understood that it does not preclude the possibility of the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof.

In various embodiments of the present disclosure, expressions such as "or" include any and all combinations of words listed together. For example, "A or B" may include A, may include B, or may include both A and B.

Expressions such as "first", "second", "first", or "second" used in various embodiments of the present disclosure may modify various elements of various embodiments, but do not limit the corresponding elements. Does not. For example, the expressions do not limit the order and/or importance of corresponding elements. The above expressions may be used to distinguish one component from another component. For example, a first user device and a second user device are both user devices and represent different user devices. For example, without departing from the scope of the rights of various embodiments of the present disclosure, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

When a component is referred to as being "connected" or "connected" to another component, the component is directly connected to or may be connected to the other component, but the component and It should be understood that new other components may exist between the other components. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it will be understood that no new other component exists between the component and the other component. Should be able to.

The terms used in various embodiments of the present disclosure are only used to describe a specific embodiment, and are not intended to limit the various embodiments of the present disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise.

Unless otherwise defined, all terms including technical or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present disclosure belong.

Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and ideal or excessively formal unless explicitly defined in various embodiments of the present disclosure. It is not interpreted in meaning.

1 is a perspective view showing a crucible assembly 100 for manufacturing a cathode active material according to an embodiment of the present invention, FIG. 2 is a perspective view showing a crucible according to an embodiment of the present invention, and FIG. 3 is a crucible of FIG. FIG. 4 is a view showing a side wall of FIG. 1, and FIG. 4 is a view showing an apparatus 1 for manufacturing a cathode active material using the crucible for manufacturing a cathode active material of FIG. 1.

1 to 4, in the crucible assembly 100 for manufacturing a positive electrode active material, a plurality of crucibles may be stacked in a height direction. Each crucible has a predetermined internal space and can pass through the cathode active material manufacturing apparatus 1.

The cathode active material manufacturing apparatus 1 may include a chamber 11 in which a heat source 12 is installed. The chamber 11 may have a rail 13 extending in the longitudinal direction and circulating in the longitudinal direction. A crucible assembly 100 for manufacturing a positive electrode active material is installed on the rail 13, and when moving along the rail 13, the positive electrode active material is generated in the crucible assembly 100 by heat supplied from the heat source 12.

The crucible assembly 100 for manufacturing a cathode active material may have various shapes having an internal space. For example, the crucible assembly 100 for manufacturing a cathode active material may have a polyhedral shape or a spherical shape. However, in the following, for convenience of description, each crucible will be described centering on an embodiment having an approximately hexahedral shape.

The crucible assembly 100 for manufacturing a positive electrode active material may include a first crucible 110 and a second crucible 120.

The first crucible 110 has an open top and may have a predetermined internal space. The first crucible 110 is disposed on the top of the crucible assembly 100 for manufacturing a positive electrode active material. A material for manufacturing a cathode active material may be stored in the inner space of the first crucible 110. As the crucible assembly 100 for manufacturing a cathode active material passes through the cathode active material manufacturing apparatus 1, the material may be synthesized as a cathode active material.

In the first crucible 110, the bottom and sidewalls are not open, but the top may be opened. Since the top of the first crucible 110 is open, sufficient heat can be transferred from the cathode active material manufacturing apparatus 1. Since the first crucible 110 passes through the cathode active material manufacturing apparatus 1 with the top open, heat generated from the cathode active material manufacturing apparatus 1 can be directly introduced into the internal space.

Since the bottom and side walls of the first crucible 110 are closed, sufficient heat for manufacturing the positive electrode active material can be maintained. When heat is transferred to the first crucible 110, since the compound constituting the bottom and the sidewall retains heat for a long time, a positive electrode active material having good quality can be manufactured in the first crucible 110.

The second crucible 120 is disposed under the first crucible 110. The second crucible 120 may have a bottom 121 and a sidewall 122. The upper part of the second crucible 120 is opened like the first crucible 110. The second crucible 120 has a predetermined internal space composed of a bottom 121 and a side wall 122, and a material for manufacturing a positive electrode active material may be stored.

The second crucible 120 may have a cut groove OP. The cut groove OP is disposed at the upper end of each side wall 122 and may have a preset open area.

In one embodiment, the cut groove OP may be disposed above the center in the height direction of the second crucible 120. The cut groove OP may be disposed at the center of the width of the sidewall 122 of the second crucible 120. When the cutting groove OP is shown in FIG. 3, the cutting groove OP may be disposed above the center line CL. Since the cut groove OP is disposed at the upper end of the sidewall 122, the second crucible 120 may secure a space in which a material for manufacturing the positive electrode active material can be stored. Since the material can be stored up to the incision groove OP, a large amount of the positive electrode active material can be manufactured in the second crucible 120.

In one embodiment, the second crucible 120 may be disposed so that the side walls 122 face each other, and a plurality of cut grooves OP may be provided, but may be disposed to overlap each other on the side walls 122. 2, the first cutout groove OP1 and the second cutout groove OP2 are arranged to face each other in the x-axis direction, and the third cutout groove OP3 and the fourth cutout groove OP4 are also in the y-axis direction. They are arranged to face each other. Since the cut grooves OP are arranged to face each other, heat generated in the cathode active material manufacturing apparatus 1 can easily move to the inner space of the second crucible 120.

In one embodiment, the open area of the cut groove OP may be set according to the following equation.

[Equation]

A _O : Open area of the incision groove, A _T : Area of the side wall of one second crucible

5 is a SEM (Scanning Electron Microscopy, SEM) photo of the cathode active material of Examples 1 to 5, and FIG. 6 is an SEM photo of the cathode active material of Comparative Examples 1 to 5.

Referring to FIGS. 5, 6, and 1, the cathode active materials synthesized in the crucible assemblies according to Examples 1 to 5 can be compared.

The crucibles were stacked in three stages to provide a crucible assembly, and each crucible has a width of W1 (horizontal and vertical length) and a height of H1 as shown in FIG. 3, and the incision groove has a width of W2 and a height of H2. In each of the Examples and Comparative Examples, by adjusting W2 and H2, the ratio (A _{O /} A _T ) occupied by the open area of the cut groove in the area of the side wall is set differently.

Composition of the synthesized cathode active material W1(mm) H1(mm) W2(mm) H2(mm) A _O / A _T Example 1 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ 300 80 120 10 0.05 Example 2 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ 300 80 200 10 0.083 Example 3 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O ₂ 300 80 280 10 0.117 Example 4 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ 300 80 120 20 0.1 Example 5 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O ₂ 300 80 120 25 0.125 Comparative Example 1 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 0 0 0 Comparative Example 2 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 60 10 0.025 Comparative Example 3 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 100 10 0.042 Comparative Example 4 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 120 5 0.025 Comparative Example 5 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 120 8 0.04

In Examples 1 to 5 and Comparative Examples 1 to 5, a cathode active material was synthesized according to the following method. First of all, 2,000 g of Ni _{0 . 8} Co _{0 .} Mn _{0 .1 1} (OH) _2, (NH4) of Li ₂ CO _3, 6g of 836g ₂ HPO _4, 60g of the mixture of WO _3, in 9g of NaOH and 15g (NH _{4) 2} S is mechanically for approximately 15 minutes do. The mixed powder was weighed in the crucibles of each of the Examples and Comparative Examples and baked at 1,000° C. for 4 hours and 700° C. for 10 hours to obtain a positive electrode active material.

5 shows scanning electron microscopy (SEM) images of Examples 1 to 5. FIG. As in Examples 1 to 5, it can be seen that a single particle type Ni-based positive electrode active material was synthesized in a crucible having an _{A O /} A _{T of 0.05 or more.}

6 shows scanning electron microscopy (SEM) images of Comparative Examples 1 to 5. As in Comparative Examples 1 to 5, in a _{crucible having an A O /} A _T of less than 0.05, a multi-particulate Ni-based positive electrode active material was prepared in which hundreds of nano-sized small particles were aggregated.

The synthesized positive electrode active material (lithium transition metal oxide) according to Examples 1 to 5 may be a single particle. A single particle is a concept that is distinguished from secondary particles formed by agglomeration of a plurality of particles or particles (multi-particles) formed by agglomeration of a plurality of particles and coating around the agglomerates. Since the lithium transition metal oxide has a single particle shape, it is possible to prevent the particles from being broken even at a high electrode density. Accordingly, it is possible to realize a high energy density of the positive electrode active material. In addition, as compared to secondary particles in which a plurality of single particles are agglomerated, breakage is suppressed during rolling, thereby enabling high energy density to be realized, and life deterioration due to breakage of particles can be prevented.

The second crucible 120 according to an embodiment of the present invention sets the _{open area (A O} ) of the minimum cut groove for _{one sidewall surface ?? (A T} ), thereby manufacturing a single particle-type cathode active material. I can. When _{the ratio of A O /} A _T is 0.05 or more, the positive electrode active material synthesized through the crucible assembly 100 has a single particle shape, so it is possible to implement a high energy density by preventing the particles from being broken even at a high electrode density. , It can also prevent the deterioration of life due to the breakage of particles. In addition, since the minimum area to be occupied by the incision groove OP can be set, the internal space of the second crucible 120 can be maximized, thereby maximizing the amount of single-particle cathode active material obtained per time.

7 is an SEM photograph of the positive electrode active material of Example 6, Comparative Example 6-1, and Comparative Example 6-2.

Referring to FIGS. 7 and 2, the cathode active materials synthesized in the crucible assemblies according to Example 6, Comparative Example 6-1, and Comparative Example 6-2 can be compared.

The crucibles were stacked in three stages to provide a crucible assembly, and each crucible has a width (horizontal and vertical length) of W1 and a height of H1, and the incision groove has a width of W2 and a height of H2. In each of the Examples and Comparative Examples, by adjusting W2 and H2, the ratio (A _{O /} A _T ) occupied by the open area of the cut groove in the area of the side wall is set differently.

Composition of the synthesized cathode active material W1(mm) H1(mm) W2(mm) H2(mm) A _O / A _T Example 6 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O ₂ 300 80 120 10 0.05 Comparative Example 6-1 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 100 10 0.0417 Comparative Example 6-2 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O _1.99 S _0.01 300 80 120 8 0.4

In Example 6, Comparative Example 6-1, and Comparative Example 6-2, a cathode active material was synthesized according to the following method. First of all, 2,000 g of Ni _{0 . 9} a _{0 .1} Co (OH) ₂ and 836g of Li ₂ CO ₃ and _{6g (NH 4) 2 HPO 4} , 60g of WO _3, 9g of NaOH, of 15g (NH _{4) 2} S is mechanically for approximately 15 minutes Mix. The mixed powder was weighed in each crucible and baked at 940°C for 4 hours and 700°C for 10 hours to obtain a positive electrode active material.

7 shows scanning electron microscopy (SEM) images of Example 6, Comparative Example 6-1, and Comparative Example 6-2. As in Example 6, it can be seen that a single particle type Ni-based positive electrode active material was synthesized in a crucible having _{A O /} A _{T of 0.05. On the other hand, in a crucible having an A O /} A _T of less than 0.05 as in Comparative Example 6-1 and Comparative Example 6-2, a multi-particulate Ni-based cathode active material in which small particles of several hundreds of nano-sized were aggregated was prepared. Even when A _{O /} A _T is 0.0417, it can be confirmed that a multi-particulate Ni-based positive electrode active material was prepared.

8 is an SEM photograph of the positive electrode active material of Example 7, Comparative Example 7-1, and Comparative Example 7-2.

Referring to FIGS. 8 and 3, the cathode active materials synthesized in the crucible assemblies according to Example 7, Comparative Example 7-1, and Comparative Example 7-2 can be compared.

The crucibles were stacked in three stages to provide a crucible assembly, and each crucible has a width (horizontal and vertical length) of W1 and a height of H1, and the incision groove has a width of W2 and a height of H2. In each of the Examples and Comparative Examples, by adjusting W2 and H2, the ratio (A _{O /} A _T ) occupied by the open area of the cut groove in the area of the side wall is set differently.

Composition of the synthesized cathode active material W1(mm) H1(mm) W2(mm) H2(mm) A _O / A _T Example 7 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O ₂ 300 80 120 10 0.05 Comparative Example 7-1 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O _1.99 S _0.01 300 80 100 10 0.0417 Comparative Example 7-1 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O _1.99 S _0.01 300 80 120 8 0.4

In Example 7, Comparative Example 7-1, and Comparative Example 7-2, a cathode active material was synthesized according to the following method. First of all, 2,000 g of Ni _{0 . 88} Co _{0 . 09} Al _{0 .03} (OH) ₂ and 836g of Li ₂ CO ₃ and 6g (NH _{4) 2} HPO ₄ a, 60g of WO _3, 9g of NaOH, of 15g (NH ₄₎ 2 _S is mechanically for approximately 15 minutes Mix. The mixed powder was weighed in a crucible and baked at 1,000° C. for 4 hours and 700° C. for 10 hours to obtain a positive electrode active material.

8 shows scanning electron microscopy (SEM) images of Example 7, Comparative Example 7-1, and Comparative Example 7-2. As in Example 7, it can be seen that a single-particle type Ni-based positive electrode active material was synthesized in a crucible having an _{A O /} A _{T of 0.05. In contrast, in a crucible having an A O /} A _T of less than 0.05 as in Comparative Example 7-1 and Comparative Example 7-2, a multi-particulate Ni-based cathode active material in which small particles of several hundreds of nanometers were aggregated was prepared. Even when A _{O /} A _T is 0.0417, it can be confirmed that a multi-particulate Ni-based positive electrode active material was prepared.

9 is a SEM photograph of the positive electrode active material of Example 8, Comparative Example 8-1, and Comparative Example 8-2.

9 and 4, the cathode active materials synthesized in the crucible assembly according to Example 8, Comparative Example 8-1, and Comparative Example 8-2 can be compared.

The crucibles were stacked in three stages to provide a crucible assembly, and each crucible has a width (horizontal and vertical length) of W1 and a height of H1, and the incision groove has a width of W2 and a height of H2. In each of the Examples and Comparative Examples, by adjusting W2 and H2, the ratio (A _{O /} A _T ) occupied by the open area of the cut groove in the area of the side wall is set differently.

Composition of the synthesized cathode active material W1(mm) H1(mm) W2(mm) H2(mm) A _O / A _T Example 8 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O ₂ 300 80 120 10 0.05 Comparative Example 8-1 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O _1.99 S _0.01 300 80 100 10 0.0417 Comparative Example 8-2 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O _1.99 S _0.01 300 80 120 8 0.4

In Example 8, Comparative Example 8-1, and Comparative Example 8-2, a cathode active material was synthesized according to the following method. First of all, 2,000 g of Ni _{0 . 8} Mn _{0 .2} to (OH) ₂ and Li ₂ CO ₃ and 6g of 836g _{(NH 4) 2 HPO 4,} 60g of WO _3, 9g of NaOH, of 15g (NH _{4) 2} S is mechanically for approximately 15 minutes Mix. The mixed powder was weighed in a crucible and baked at 950° C. for 4 hours and 700° C. for 10 hours to obtain a positive electrode active material.

9 shows scanning electron microscopy (SEM) images of Example 8, Comparative Example 8-1, and Comparative Example 8-2. As in Example 8, it can be seen that a single particle type Ni-based positive electrode active material was synthesized in a crucible having _{A O /} A _{T of 0.05. On the other hand, in a crucible having an A O /} A _T of less than 0.05 as in Comparative Example 8-1 and Comparative Example 8-2, a multi-particulate Ni-based cathode active material in which small particles of several hundreds of nano-sized were aggregated was prepared. Even when A _{O /} A _T is 0.0417, it can be confirmed that a multi-particulate Ni-based positive electrode active material was prepared.

In one embodiment, at least one of the first crucible 110 and the second crucible 120 is formed of a compound represented by the following formula. Preferably, the first crucible 110 and the second crucible 120 are formed of a compound represented by the following formula.

[Chemical Formula]

xAl ₂ O ₃ yMgO zSiO ₂ (0.9<x<1, 0<y<0.1, 0<z<0.1, x+y+z=1)

Components of the crucible for synthesizing the powders of Comparative Examples and Examples are shown in Table 5 below. The crucible specified in Table 5 _{is composed of a three-component system of Al 2} O ₃ , MgO and SiO ₂ , and crucible A is an industrially commercialized mullite crucible.

Crucible B and crucible C have a composition that satisfies the above formula, but crucible A has a composition deviating from the above formula. Crucible A was used for the synthesis of the comparative example, and crucibles B and C were used for the synthesis of the example.

Al ₂ O ₃ (%) MgO (%) SiO ₂ (%) Crucible A 67.8 17.4 14.8 Crucible B 92.5 8.4 9.1 Crucible C 97.5 1.1 1.4

10 is a graph showing particle size distribution of positive electrode active materials of Examples 9-1, 9-2, and Comparative Example 9.

Example 9-1, Example 9-2, and Comparative Example 9 are each 100 g of Ni _{0 . 8} Co _{0 . 1} Mn _{0 .1} (OH) of Li ₂ CO ₃ and 0.30g of ₂ and _{41.8g (NH 4) 2 HPO 4} , 3.0g of WO _3, 0.45g of NaOH, of 0.75g (NH _{4) 2} S to Mix mechanically for about 15 minutes. The mixed powder was weighed in crucible A (Comparative Example 9), crucible B (Example 9-1), and crucible C (Example 9-2) and baked at 1,000° C. for 4 hours and 700° C. for 10 hours to obtain a positive electrode active material. .

10 shows particle size distribution results of positive electrode active materials prepared according to Example 9-1, Example 9-2, and Comparative Example 9. Example 9-1, Example 9-2, and Comparative Example 9 are LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811). It can be seen that as the composition of Al ₂ O _{3 in} the crucible increases, the fine powder content of less than 1 μm is reduced. Moreover, it can be seen that the average particle diameter (D ₅₀ ) _{of the powder also increases as the composition of Al 2} O _{3 in the crucible increases. This is because Al 2} O ₃ among the three components constituting the crucible has the highest thermal conductivity, so the Al ₂ O ₃ content in the crucible increases, so even if the crucible is fired at the same temperature, the average temperature of the crucible is high and particles can grow further. .

Hereinafter, the fine powder of the positive electrode active material is defined as having a size of less than 1 μm produced from the synthesized positive electrode active material. When an excessive amount of fine powder (1<μm) is formed during the synthesis of a single-particle Ni-based positive electrode active material through firing at a high temperature, the specific surface area of the positive electrode active material powder may increase, leading to a decrease in electrochemical performance.

In particular, unstable Ni ions on the surface of the positive electrode particles promote side reactions of the electrolyte solution during continuous charging/discharging and at the same time form an electrochemically inert phase, thereby deteriorating the lifespan. When an electrochemically inert phase is generated, oxygen is released into the structure of the positive electrode active material, thereby reducing the stability of the positive electrode active material. Since this structural instability is also related to the specific surface area of the powder, this means that it is essential to reduce the specific surface area of the powder by removing fine powders (1<μm) in order to secure long life stability.

The crucible assembly according to an embodiment _{contains 90% or more of Al 2} O ₃ , and the positive electrode active material synthesized in the crucible assembly may reduce a fine powder content of less than 1 μm and a specific surface area of the powder.

10 and Table 6, _{it can be seen that as the content of Al 2} O _{3 in} the crucible increases, the excess fine powder present on the particle surface is reduced, and it can be seen that the average size of the powder is further grown. When the average size of the powder increases, the specific surface area of the powder can be reduced as shown in Table 7. Comparing the respective specific surface, Comparative Example 9 is 0.67m ² / g, in Example 9-1 was 0.58m ² / g and Example 9-2 0.35m ² / g. This means that the electrochemical lifetime will be improved through the reduction of the specific surface area of the positive electrode active material.

Fine powder content less than 1 μm (vol.%) D ₁₀ (㎛) D ₅₀ (㎛) D ₉₀ (㎛) Comparative Example 9 One 2.9 5.5 10.7 Example 9-1 0.27 2.8 5.8 10.7 Example 9-2 0.03 2.7 6.5 11.2

Specific surface area (m ² /g) Comparative Example 9 0.67 Example 9-1 0.58 Example 9-2 0.35

11 is a graph of life retention rates for the half cells of Example 9-1, Example 9-2, and Comparative Example 9. FIG.

For the electrochemical evaluation of the example, a 2032 R coin type half cell (Welcos) was used, and the composition of the positive electrode active material electrode plate for a lithium secondary battery was 94:3 as a positive electrode active material, a conductive material (Super-P), and a binder (PVdF, KF9300). It consists of a weight ratio of :3. The loading level of the electrode plate is 11mg/cm ² and the electrode density is 3.6g/cc. The electrolyte was 1.3M LiPF6 ethylene carbonate (EC) / ethly methyl carbonate (EMC) / dimethyl carbonate (DMC) = 3/4/3 (v/v/v).

The electrochemical evaluation of the comparative example is the same as the evaluation method of the example. After 10 hours of rest (rest) process for initial Mars evaluation, charge the assembled cell in CC (constant current) mode to 4.3V at 0.1C, and then charge it in CV (constant voltage) mode to a current corresponding to 0.05C. I did. Then, discharge was performed in CC mode to 3.0V at 0.1C. For the room temperature life evaluation, after charging in CC mode up to 4.3V at 0.5C, charging was performed in CV mode up to a current corresponding to 0.05C. Next, discharge was performed in CC mode to 3.0V at 1C, and this process was repeated a total of 50 times.

Regarding the initial capacity, the capacity retention rate after charging and discharging 50 times was calculated, and the results are shown in Table 8 below. In addition, a graph showing the capacity retention rate according to the cycle is shown in FIG. 11.

Furtherance Crucible type 50 cycle room temperature life retention rate (%) Example 9-1 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ B 87.8 Example 9-2 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ C 93.1 Comparative Example 9 Li _0.99 Na _0.01 Ni _0.795 Co _0.1 Mn _0.1 W _0.01 O ₂ A 81.3

Referring to Table 8 and FIG. 11, according to the room temperature life results of Example 9-1, Example 9-2, and Comparative Example 9, Example 9-1 showed about 6% higher life retention rate after 50 cycles compared to Comparative Example 9. Is shown, Example 9-2 shows a life retention rate of about 12% higher than that of Comparative Example 9. This shows that the lifetime maintenance rate is improved as the specific surface area of the powder is reduced through fine powder control.

12 is a graph of life retention rates for the half cells of Examples 10-1, 10-2, and Comparative Example 10;

Example 10-1, Example 10-2, and Comparative Example 10 are each 100 g of Ni _{0 . 80} Co _{0 . 15} Al _{0 .05} (OH) ₂ and Li ₂ CO _3, and 42.0g of _{0.30g (NH 4) 2 HPO 4} , 3.0g of WO _3, 0.45g of NaOH, of 0.75g (NH _{4) 2} S to Mix mechanically for about 15 minutes. The mixed powder was weighed in crucible A (Comparative Example 10), crucible B (Example 10-1), and crucible C (Example 10-2) and baked at 1,000° C. for 4 hours and 700° C. for 10 hours to obtain a positive electrode active material. .

For Example 10-1, Example 10-2, and Comparative Example 10, the capacity retention rate after charging and discharging 50 times for each initial capacity was calculated, and the results are shown in Table 9 below. In addition, a graph showing the capacity retention rate according to the cycle is shown in FIG. 12.

Furtherance Crucible type 50 cycle room temperature life retention rate (%) Example 10-1 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O ₂ B 86.8 Example 10-2 Li _0.99 Na _0.01 Ni _0.795 Co _0.15 Al _0.05 W _0.01 O ₂ C 92.1 Comparative Example 10 Li _{0 . 99} Na _{0 . 01} Ni _{0 . 795} Co _{0 . 15} Al _{0 . 05} W _{0 . 01} O ₂ A 80.4

Referring to Tables 9 and 12, according to the room temperature life results of Example 10-1, Example 10-2, and Comparative Example 10, Example 10-1 shows a life retention rate of about 6% higher than that of Comparative Example 10, Example 10-2 shows a life retention rate of about 12% higher than that of Comparative Example 10. This shows that the lifetime maintenance rate is improved as the specific surface area of the powder is reduced through fine powder control.

13 is a graph of life retention rates for the half cells of Example 11-1, Example 11-2, and Comparative Example 11. FIG.

Example 11-1, Example 11-2, and Comparative Example 11 are each 100 g of Ni _{0 . 90} Co _{0 .10} (OH) of Li ₂ CO ₃ and 0.30g of ₂ and _{41.5g (NH 4) 2 HPO 4} , 3.0g of WO _3, 0.45g of NaOH, of 0.75g (NH _{4) 2} S to Mix mechanically for about 15 minutes. The mixed powder was weighed in crucible A (Comparative Example 11), crucible B (Example 11-1), and crucible C (Example 11-2) to obtain a cathode active material through firing at 940°C for 4 hours and 700°C for 10 hours. .

For Example 11-1, Example 11-2, and Comparative Example 11, the capacity retention rate after charging and discharging 50 times for each initial capacity was calculated, and the results are shown in Table 10 below. In addition, a graph showing the capacity retention rate according to the cycle is shown in FIG. 13.

Furtherance Crucible type 50 cycle room temperature life retention rate (%) Example 11-1 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O ₂ B 77.1 Example 11-2 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O ₂ C 80.9 Comparative Example 11 Li _0.99 Na _0.01 Ni _0.895 Co _0.10 W _0.01 O ₂ A 74.0

Referring to Table 10 and Figure 13, according to the room temperature life results of Example 11-1, Example 11-2, and Comparative Example 11, Example 11-1 shows a life retention rate of about 3% higher than that of Comparative Example 11, Example 11-2 shows about 7% higher life retention rate compared to Comparative Example 11. This shows that the lifetime maintenance rate is improved as the specific surface area of the powder is reduced through fine powder control.

14 is a graph of life retention rates for half cells of Example 12-1, Example 12-2, and Comparative Example 12. FIG.

Example 12-1, Example 12-2, and Comparative Example 12 are each 100 g of Ni _{0 . 80} Mn _{0 .10} (OH) of Li ₂ CO ₃ and 0.30g of ₂ and _{41.3g (NH 4) 2 HPO 4} , 3.0g of WO _3, 0.45g of NaOH, of 0.75g (NH _{4) 2} S to Mix mechanically for about 15 minutes. The mixed powder was weighed in a crucible A (Comparative Example 12), a crucible B (Example 12-1), and a crucible C (Example 12-2) and baked at 950° C. for 4 hours and 700° C. for 10 hours. A cathode active material was obtained.

For Example 12-1, Example 12-2, and Comparative Example 12, the capacity retention rate after charging and discharging 50 times for each initial capacity was calculated, and the results are shown in Table 11 below. In addition, a graph showing the capacity retention rate according to the cycle is shown in FIG. 14.

Furtherance Crucible type 50 cycle room temperature life retention rate (%) Example 12-1 Li _0.99 Na _0.01 Ni _0.795 Mn _0.20 W _0.01 O ₂ B 83.7 Example 12-2 Li _0.99 Na _0.01 Ni _0.795 Mn _0.20 W _0.01 O ₂ C 90.0 Comparative Example 12 Li _{0 . 99} Na _{0 . 01} Ni _{0 . 895} Mn _{0 . 20} W _{0 . 01} O ₂ A 70.7

Referring to Table 11 and FIG. 14, according to the room temperature life results of Example 12-1, Example 12-2, and Comparative Example 12, Example 12-1 shows a life retention rate of about 13% higher than that of Comparative Example 12, Example 12-2 shows a life retention rate of about 19% higher than that of Comparative Example 12. This shows that the lifetime maintenance rate is improved as the specific surface area of the powder is reduced through fine powder control.

The crucible and the cathode active material produced by the crucible assembly of the embodiments of the present invention are as follows.

A positive electrode active material according to an aspect includes a core including a lithium transition metal oxide including W and B; And a phosphorus-containing coating layer including a phosphorus-containing compound disposed on the surface of the core.

In the positive electrode active material, B and W elements are introduced into the lithium transition metal oxide, thereby improving structural stability due to an increase in the ordering of Ni ions contained in the transition metal oxide, and increasing the bonding strength between the transition metal and oxygen. As a result, oxygen emission is suppressed during charging and discharging of the lithium battery, and through this, side reactions with the electrolyte may be suppressed to prevent depletion of the electrolyte.

In addition, by including a phosphorus-containing coating layer including a phosphorus-containing compound on the surface of the core containing the lithium transition metal oxide, the phosphorus-containing compound reacts preferentially with HF derived from the binder and the electrolyte to transfer lithium In addition to suppressing side reactions with metal oxides, the phosphorus-containing compound may preferentially react with moisture present in the electrolyte to suppress side reactions with lithium transition metal oxides. As a result, by suppressing deterioration due to side reactions of the lithium transition metal oxide, the life characteristics are improved.

According to one embodiment, of the positive electrode active material, the lithium transition metal oxide may be represented by the following Formula 1:

[Formula 1]

Li _1-x A _x W _α B _β M _1-α-β O _2-y T _y

In Formula 1,

A is one or more elements selected from the group consisting of Na, K, Rb and Cs,

T is at least one element selected from the group consisting of S, F and P,

M includes at least one element selected from the group consisting of Ni, Co, Mn, Al, Mg, V, Ti and Ca,

0<x≤0.01, 0<y≤0.01, 0<α≤0.01, 0<β≤0.01.

In addition to including W and B, the lithium transition metal oxide includes W and B, as represented by Chemical Formula 1, when a part of Li in the lithium transition metal oxide is replaced with a small amount of alkali metal, when charging the lithium battery, Li Structural stability of the lithium transition metal oxide is improved by suppressing the deformation of the structure due to the desorption of ions.

In addition, as represented by Chemical Formula 1, when a part of oxygen in the lithium transition metal oxide is substituted with any one of S, F, and P having a higher electronegativity than oxygen, when combined with oxygen In comparison, the transition metal can be preserved in the structure by a higher bonding force, the bonding force between the elements located in the oxygen lattice site is increased, the electron mobility is improved, and the conductivity is improved. Therefore, the high rate cycle characteristics can also be improved.

In addition to including W and B, the lithium transition metal oxide includes W and B, as represented by Chemical Formula 1, when a part of Li in the lithium transition metal oxide is replaced with a small amount of alkali metal, when charging the lithium battery, Li Structural stability of the lithium transition metal oxide is improved by suppressing the deformation of the structure due to the desorption of ions.

In addition, as represented by Chemical Formula 1, when a part of oxygen in the lithium transition metal oxide is substituted with any one of S, F, and P having a higher electronegativity than oxygen, when combined with oxygen In comparison, the transition metal can be preserved in the structure by a higher bonding force, the bonding force between the elements located in the oxygen lattice site is increased, the electron mobility is improved, and the conductivity is improved. Therefore, the high rate cycle characteristics can also be improved.

According to an embodiment, in Formula 1, A may be Na, and T may be S.

According to an embodiment, in Formula 1, M is M1, M2, and M3, and M1 is Ni, and M2 and M3 are independently of each other in Co, Mn, Al, Mg, V, Ti, and Ca. It is a selected element, and the molar ratio of Ni in M may be 75 mol% or more.

According to another embodiment, in Formula 1, M is selected from M1, M2 and M3, M1 is Ni, M2 is Co, and M3 is selected from Mn, Al, Mg, V, Ti, and Ca. Element, and the molar ratio of Ni in M may be 75 mol% or more.

According to another embodiment, in Formula 1, M includes M1 and M2, M1 is Ni, M2 is Co, and the molar ratio of Ni in M may be 75 mol% or more.

According to one embodiment, the lithium transition metal oxide may be represented by any one of the following Formulas 2 to 4:

[Formula 2]

_{Li 1-x 'Na x'} W α 'B β' Ni γ 'Co δ' Mn ε 'O 2-y' S y '

[Formula 3]

Li _1-x'' Na _x'' W _α'' B _β'' Ni _γ'' Co _δ'' Al _ε'' O _2-y'' S _y''

[Formula 4]

Li _1-x''' Na _x''' W _α''' B _β''' Ni _γ''' Co _δ''' O _2-y''' S _y'''

In Formula 2, 0<x'≤0.01, 0<y'≤0.01, 0<α'≤0.01, 0<β'≤0.01, 0.48≤γ'<1, 0<δ'≤0.2, 0<ε' ≤0.3, α'+β'+γ'+δ'+ε'=1,

In Formula 3, 0<x''≤0.01, 0<y''≤0.01, 0<α''≤0.01, 0<β''≤0.01, 0.73≤γ''<1, 0<δ''≤ 0.2, 0<ε''≤0.05, α''+β''+γ''+δ''+ε''=1,

In Formula 4, 0<x'''≤0.01, 0<y'''≤0.01, 0<α'''≤0.01, 0<β'''≤0.01, 0.78≤γ'''<1, 0 <δ'''≤0.2.

According to one embodiment, the lithium transition metal oxide may be a single particle. A single particle is a concept that is distinguished from secondary particles formed by agglomeration of a plurality of particles or particles formed by agglomeration of a plurality of particles and coating around the agglomerates. Since the lithium transition metal oxide has a single particle shape, it is possible to prevent the particles from being broken even at a high electrode density. Accordingly, it is possible to realize a high energy density of the positive electrode active material. In addition, as compared to secondary particles in which a plurality of single particles are agglomerated, breakage is suppressed during rolling, thereby enabling high energy density to be realized, and life deterioration due to breakage of particles can be prevented.

According to one embodiment, the lithium transition metal oxide may have a single crystal. Single crystals have a concept that is distinct from single grains. A single particle refers to a particle formed of one particle regardless of the type and number of crystals therein, and a single crystal refers to having only one crystal in the particle. Since the core has a single crystal, structural stability is very high, and lithium ion conduction is easier than that of polycrystal, and high-speed charging characteristics are superior to that of a polycrystalline active material.

According to one embodiment, the positive electrode active material is a single crystal and a single particle. By being formed of a single crystal and a single particle, structurally stable and high-density electrodes can be implemented, and a lithium secondary battery including the same can have improved life characteristics and high energy density at the same time.

The positive electrode active material represented by Formulas 2 to 4 has a single crystal and a single particle, a part of Li is substituted with Na in the lithium transition metal oxide, a part of the transition metal is substituted with W and B, and a part of O is replaced by S. As it is substituted, structural stability can be remarkably improved to exhibit long life characteristics.

In the case of a cathode active material containing a general high-nickel lithium nickel cobalt manganese oxide, stabilization of unstable Ni ions is essential.W and B are introduced into some of the transition metal sites in the crystal, so that the cathode active material can achieve an overall charge balance. As a result, oxidation from Ni(II) ions to unstable Ni(III) or Ni(IV) ions can be suppressed, and unstable Ni(III) or Ni(IV) can be reduced to Ni(II). On the other hand, the loss of conductivity due to substituting part of the transition metal with B and W, which are heterogeneous elements, was compensated by substituting part of O with S. As part of Li was substituted with Na, structural deformation during charging and discharging By also suppressing the decrease in the conductivity of Li, a positive electrode active material having a high capacity and long life, which is structurally stable in a single crystal, was obtained. Furthermore, in order to suppress the side reaction between the lithium transition metal oxide and the electrolyte or moisture, a phosphorus-containing compound, for example, a phosphorus-containing coating layer including Li3PO4 was introduced on the surface of the lithium transition metal oxide. This phosphorus-containing compound prevents side reactions with HF derived from the electrolyte or moisture present in the electrolyte, thereby ensuring high stability and long life characteristics.

According to one embodiment, the core including the lithium transition metal compound may have a uniform composition over the entire range. Accordingly, a structurally stable structure can be maintained even during charging and discharging, and since it does not interfere with the movement of lithium, it has a high rate characteristic.

According to one embodiment, the phosphorus-containing compound may be crystalline, amorphous, or a combination thereof.

For example, the phosphorus-containing compound may include a crystalline Li3PO4 or an amorphous phosphorus-containing compound including lithium, phosphorus and oxygen atoms.

According to one embodiment, the molar ratio of the phosphorus (P) element in the positive electrode active material may be 0.2 mol% or less of the total elements included in the positive electrode active material.

According to one embodiment, the phosphorus-containing compound may include a compound represented by the following formula (5):

[Formula 5]

Li _a P _b O _c

0<a≤3, 0<b≤1, and 0<c≤4.

According to one embodiment, the coating layer may have a continuous coating layer on the core surface or an island-shaped coating layer partially present on the core surface. For example, the coating layer may have an island-shaped coating layer on the surface of the core.

According to one embodiment, the coating layer may have a thickness of several nanometers. For example, the coating layer may be 1 nm to 10 nm.

According to one embodiment, the positive electrode active material may have a peak at 2θ = 20° to 25° of an X-ray diffraction spectrum obtained by XRD analysis using CuKα rays.

For example, the positive electrode active material may have peaks at at least 2θ = 22.3°±0.5, 23.0°±0.5, and 24.8°±0.5 in the X-ray diffraction spectrum obtained by XRD analysis using CuKα rays.

The peak at 2θ = 20° to 25° in the X-ray diffraction spectrum indicates the presence _{of Li 3} PO _4. In addition, as will be described later, since this peak is observed in the coating layer of the positive electrode active material, it can be seen that the positive electrode active material does not contain the P element inside the core.

The coating layer including the phosphorus-containing compound, for example Li ₃ PO ₄ , is a residual lithium compound generated during the synthesis of a Ni-based positive electrode active material, for example, Li ₂ CO ₃ , and is a reaction product of a phosphorus-containing compound with LiOH, Accordingly, generation of gas due to a side reaction between the residual lithium compound and the electrolyte is suppressed, thereby improving the stability of the battery. In addition, _{the coating layer including Li 3} PO ₄ has high ionic conductivity and thus can promote the diffusion of lithium ions.

According to one embodiment, the average particle diameter (D ₅₀ ) of the positive electrode active material may be 0.1 μm to 20 μm. For example, the average particle diameter (D ₅₀ ) is 0.1 μm to 15 μm, 0.1 μm to 10 μm, 1 μm to 20 μm, 5 μm to 20 μm, 1 μm to 15 μm, 1 μm to 10 μm, 5 μm To 15 μm, or 5 μm to 10 μm. When the average particle diameter of the positive electrode active material falls within the above range, a desired energy density per volume may be achieved. When the average particle diameter of the positive electrode active material exceeds 20 μm, the charge/discharge capacity rapidly decreases, and when it is less than 0.1 μm, it is difficult to obtain a desired energy density per volume.

Hereinafter, a method of manufacturing a positive electrode active material according to an aspect will be described in detail.

The method for preparing a cathode active material according to an embodiment is a lithium transition by mixing a Li element-containing compound, W element-containing compound, B element-containing compound, A element-containing compound, M element-containing compound, T element-containing compound, and P element-containing compound. Obtaining a metal oxide precursor; And heat-treating the precursor to obtain a positive electrode active material including a lithium transition metal oxide represented by Formula 1 below, wherein the lithium transition metal oxide includes a phosphorus-containing coating layer on the surface:

[Formula 1]

Li _1-x A _x W _α B _β M _1-α-β O _2-y T _y

In Formula 1,

A is one or more elements selected from the group consisting of Na, K, Rb and Cs,

T is at least one element selected from the group consisting of S, F and P,

M includes at least one element selected from the group consisting of Ni, Co, Mn, Al, Mg, V, Ti and Ca,

0<x≤0.01, 0<y≤0.01, 0<α≤0.01, 0<β≤0.01.

For a detailed description of Chemical Formula 1, refer to the foregoing.

The mixing step includes mechanical mixing the specific element-containing compounds. The mechanical mixing is carried out dry. The mechanical mixing is to form a uniform mixture by pulverizing and mixing materials to be mixed by applying a mechanical force. Mechanical mixing is a mixing device such as a ball mill, planetary mill, stirred ball mill, vibrating mill, etc. using chemically inert beads. This can be done using At this time, in order to maximize the mixing effect, alcohol such as ethanol and higher fatty acids such as stearic acid may be selectively added in a small amount.

The mechanical mixing is carried out in an oxidizing atmosphere, which is to prevent reduction of the transition metal in the transition metal source (eg, Ni compound), thereby realizing structural stability of the active material.

The lithium element-containing compound may include lithium hydroxide, oxide, nitride, carbonate, or a combination thereof, but is not limited thereto. For example, the lithium precursor may be LiOH or Li ₂ CO ₃ .

The element A-containing compound may include a hydroxide, oxide, nitride, carbonate, or a combination of at least one element selected from the group consisting of Na, K, Rb, and Cs, but is not limited thereto. For example, it may be NaOH, Na ₂ CO ₃ , KOH, K ₂ CO ₃ , RbOH, Rb ₂ CO ₃ , CsOH or Cs ₂ CO ₃ .

The W precursor may include a hydroxide, oxide, nitride, carbonate, or a combination thereof of W, but is not limited thereto. For example, it may be W(OH) ₆ , WO ₃ or a combination thereof.

The B element-containing compound may include a hydroxide, oxide, nitride, carbonate, or a combination thereof of B, but is not limited thereto. For example, it may be B(OH) ₃ , B ₂ O ₃ , or a combination thereof.

The M element-containing compound may include, but is not limited to, hydroxides, oxides, nitrides, carbonates, or combinations thereof of at least one element of Ni, Co, Mn, Al, Mg, V, Ti, and Ca.

The T element-containing compound may include, but is not limited to, a hydroxide, oxide, nitride, carbonate, ammonium, or a combination of one or more elements of S, F, and P. For example, it may be _{(NH 4} ) _{2 S.}

The P element-containing compound includes all compounds capable of providing the P element. For example, it may be _{(NH 4} ) ₂ HPO _4.

After the mixing step, it may include a step of heat treatment. The heat treatment step may include a first heat treatment step and a second heat treatment step. The first heat treatment step and the second heat treatment step may be performed continuously or may have a rest period after the first heat treatment step. In addition, the first heat treatment step and the second heat treatment step may be performed in the same chamber or may be performed in different chambers.

The heat treatment temperature in the first heat treatment step may be higher than the heat treatment temperature in the second heat treatment step.

The first heat treatment step may be performed at a heat treatment temperature of 800°C to 1200°C. The heat treatment temperature may be, for example, 850°C to 1200°C, 860°C to 1200°C, 870°C to 1200°C, 880°C to 1200°C, 890°C to 1200°C, or 900°C to 1200°C, but limited thereto It does not, and includes all the ranges configured by selecting any two points within the range.

The second heat treatment step may be performed at a heat treatment temperature of 700°C to 800°C. The heat treatment temperature is 710 ℃ to 800 ℃, 720 ℃ to 800 ℃, 730 ℃ to 800 ℃, 740 ℃ to 800 ℃, 750 ℃ to 800 ℃, 700 ℃ to 780 ℃, 700 ℃ to 760 ℃, 700 ℃ to 750 ℃, or 700 ℃ to 730 ℃ may be, but is not limited thereto, and includes all ranges configured by selecting any two points within the above range.

According to one embodiment, the heat treatment time in the first heat treatment step may be shorter than the heat treatment time in the second heat treatment step.

For example, the heat treatment time in the first heat treatment step may be 3 hours to 5 hours, 4 hours to 5 hours, or 3 hours to 4 hours, but is not limited thereto, and any two points within the above range are selected. It includes all of the ranges constructed by this.

For example, the heat treatment time in the second heat treatment step may be 10 to 20 hours, 10 to 15 hours, but is not limited thereto, and includes all ranges configured by selecting any two points within the range. .

The first heat treatment step may include performing heat treatment at a heat treatment temperature of 800° C. to 1200° C. for 3 to 5 hours.

The second heat treatment step may include performing heat treatment at a heat treatment temperature of 700° C. to 800° C. for 10 to 20 hours.

In the first heat treatment step, the lithium transition metal oxide forms the positive electrode active material having a layered structure and at the same time causes the growth of particles, thereby forming a single crystal shape. In the first heat treatment step, the primary particles in the lithium transition metal oxide in the form of secondary particles rapidly grow and are fused to each other while revealing the inside of the primary particles as they cannot withstand the stress between the particles. It is thought to be formed. The second heat treatment step increases the crystallinity of the layered structure generated in the first heat treatment step by performing heat treatment at a lower temperature in the first heat treatment step for a long time. Through the first and second heat treatment steps, a single phase, single crystal, and single particle nickel-based positive electrode active material may be obtained.

According to one embodiment, the lithium transition metal oxide prepared by the above manufacturing method is a single crystal or a single particle, and the single crystal may have a layered structure. In addition, the average particle diameter of the lithium transition metal oxide may be 0.1 μm to 20 μm.

In addition, in the positive electrode active material prepared by the method for preparing the positive electrode active material, W and B elements are substituted for Ni in the structure, and T element, for example, S element is substituted for O. In addition, since the A element is substituted at the position of Li, ^{the oxidation of Ni 2 +} is suppressed, and reduction of the existing unstable Ni ^{3 +} ions to Ni ^{2 +} ions is induced. The reduced Ni ^{2 +} ions and Li ⁺ ions have similar ionic radii, which promotes Li/Ni disordering, partially changing the oxygen lattice structure in the core. Due to the partial change of the oxygen lattice structure, the P element occupies a tetrahedral position in the _{structure, so that the PO 4} structure cannot be formed, so that the P element cannot penetrate into the tetrahedral position in the core, and a phosphorus-containing compound, for example, on the surface of the positive electrode active material. It exists in the form of _{Li 3} PO _4.

In addition, the positive electrode active material prepared by the above method includes a coating layer including a phosphorus-containing compound on the surface, thereby obtaining a positive electrode active material in which the amount of residual lithium and the amount of unstable Ni ions are simultaneously reduced. The secondary battery has a high energy density and a long life.

According to another aspect, a positive electrode including the positive electrode active material described above is provided.

According to another aspect, the anode; cathode; And there is provided a lithium secondary battery comprising; an electrolyte.

The positive electrode and a lithium secondary battery including the same may be manufactured by the following method.

First, the anode is prepared.

For example, a positive electrode active material composition in which the above-described positive electrode active material, conductive material, binder, and solvent are mixed is prepared. The positive electrode active material composition is directly coated on a metal current collector to prepare a positive electrode plate. Alternatively, the positive electrode active material composition may be cast on a separate support, and then a film peeled from the support may be laminated on a metal current collector to prepare a positive electrode plate. The anode is not limited to the shapes listed above, and may be of a shape other than the above shape.

Examples of the conductive material include graphite such as natural graphite and artificial graphite; Carbon black; Conductive tubes such as carbon nanotubes; Conductive whiskers such as fluorocarbon, zinc oxide, and potassium titanate; Conductive metal oxides such as titanium oxide; And the like may be used, but are not limited thereto, and any material that can be used as a conductive material in the art may be used.

As the binder, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene, mixtures thereof, metal salts, or styrene butadiene Rubber-based polymers and the like may be used, but are not limited thereto, and any one that can be used as a binder in the art may be used. As another example of the binder, lithium salt, sodium salt, calcium salt or Na salt of the above-described polymer may be used.

As the solvent, N-methylpyrrolidone, acetone, or water may be used, but are not limited thereto, and any solvent that can be used in the art may be used.

The contents of the positive electrode active material, the conductive material, the binder, and the solvent are the levels commonly used in lithium batteries. Depending on the use and configuration of the lithium battery, one or more of the conductive material, the binder, and the solvent may be omitted.

Next, the cathode is prepared.

For example, an anode active material composition is prepared by mixing an anode active material, a conductive material, a binder, and a solvent. The negative electrode active material composition is directly coated and dried on a metal current collector having a thickness of 3 μm to 500 μm to prepare a negative electrode plate. Alternatively, after the negative active material composition is cast on a separate support, a film peeled from the support may be laminated on a metal current collector to prepare a negative electrode plate.

The negative electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in the battery, and for example, a surface-treated copper, nickel, or copper surface with carbon may be used.

The negative active material may be any material that can be used as a negative active material for lithium batteries in the art. For example, it may include at least one selected from the group consisting of lithium metal, a metal alloyable with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material.

For example, the metal alloyable with lithium is Si, Sn, Al, Ge, Pb, Bi, Sb Si-Y alloy (wherein Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth Element or a combination element thereof, not Si), Sn-Y alloy (the Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combination element thereof, but not Sn ), etc. The element Y is Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, It may be Se, or Te.

For example, the transition metal oxide may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like.

For example, the non-transition metal oxide may be SnO ₂ , SiOx (0<x<2), or the like.

The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as amorphous, plate-shaped, flake, spherical or fibrous natural graphite or artificial graphite, and the amorphous carbon is soft carbon (low temperature calcined carbon) or hard carbon (hard carbon). carbon), mesophase pitch carbide, calcined coke, and the like.

In the negative electrode active material composition, the conductive material, the binder, and the solvent may be the same as those of the positive electrode active material composition.

The contents of the negative electrode active material, the conductive material, the binder, and the solvent are the levels commonly used in lithium batteries. Depending on the use and configuration of the lithium battery, one or more of the conductive material, the binder, and the solvent may be omitted.

Next, a separator to be inserted between the anode and the cathode is prepared.

Any of the separators can be used as long as they are commonly used in lithium batteries. A material having low resistance to ion movement of the electrolyte and excellent in the ability to impregnate the electrolyte may be used. The separator may be a single film or a multilayer film, for example, as selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), or a combination thereof. , It may be in the form of non-woven fabric or woven fabric. Further, a mixed multilayer film such as a polyethylene/polypropylene two-layer separator, a polyethylene/polypropylene/polyethylene three-layer separator, a polypropylene/polyethylene/polypropylene three-layer separator, and the like may be used. For example, a rollable separator such as polyethylene or polypropylene may be used for a lithium ion battery, and a separator having excellent organic electrolyte impregnation ability may be used for a lithium ion polymer battery. For example, the separator may be manufactured according to the following method.

A separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition may be directly coated and dried on an electrode to form a separator. Alternatively, after the separator composition is cast and dried on a support, a separator film peeled from the support may be laminated on an electrode to form a separator.

The polymer resin used for manufacturing the separator is not particularly limited, and all materials used for the bonding material of the electrode plate may be used. For example, vinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or mixtures thereof may be used.

Next, the electrolyte is prepared.

For example, the electrolyte may be an organic electrolyte. In addition, the electrolyte may be a solid. For example, it may be boron oxide, lithium oxynitride, or the like, but is not limited thereto, and any one that can be used as a solid electrolyte in the art may be used. The solid electrolyte may be formed on the negative electrode by a method such as sputtering.

For example, the organic electrolyte may be prepared by dissolving a lithium salt in an organic solvent.

The organic solvent may be used as long as it can be used as an organic solvent in the art. Cyclic carbonates, such as propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, and vinylene carbonate, for example; Chain carbonates such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate and dibutyl 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; And amides such as dimethylformamide. These can be used alone or in combination of a plurality of them. For example, a solvent in which a cyclic carbonate and a chain carbonate are mixed can be used.

In addition, a gel polymer electrolyte obtained by impregnating a polymer electrolyte such as polyethylene oxide and polyacrylonitrile with an electrolyte solution, or LiI, Li ₃ N, Li _x Ge _y P _z S _α , Li _x Ge _y P _z S _α X _δ ( Inorganic solid electrolytes, such as X=F, Cl, Br), can be used.

The lithium salt may also be used as long as it can be used as a lithium salt in the art. For example, 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 , LiAlO ₂ , LiAlCl ₄ , LiN(C _x F _{2x + 1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x,y are natural numbers), LiCl, LiI, or a mixture thereof.

The positive electrode active material according to an embodiment of the present invention may have excellent stability even when a fluorine-containing electrolyte is used due to the presence of a coating layer including a phosphorus-containing compound.

15 is a schematic diagram of a lithium battery according to an exemplary embodiment.

As shown in FIG. 15, the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 described above are wound or folded to be accommodated in the battery case 5. Subsequently, an organic electrolyte is injected into the battery case 5 and sealed with a cap assembly 6 to complete the lithium battery 1. The battery case 5 may be a cylindrical shape, a square shape, a pouch type, a coin type, or a thin film type. For example, the lithium battery 1 may be a thin film type battery. The lithium battery 1 may be a lithium ion battery.

A separator may be disposed between the positive electrode and the negative electrode to form a battery structure. After the battery structure is stacked in a bi-cell structure, it is impregnated with an organic electrolytic solution, and the resulting product is accommodated in a pouch and sealed to complete a lithium ion polymer battery.

In addition, a plurality of the battery structures are stacked to form a battery pack, and the battery pack can be used in all devices requiring high capacity and high output. For example, it can be used for laptop computers, smart phones, electric vehicles, and the like.

In addition, since the lithium battery has excellent life characteristics and high rate characteristics, it can be used in an electric vehicle (EV). For example, it can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in a field where a large amount of power storage is required. For example, it can be used for electric bicycles, power tools, power storage systems, and the like.

As described above, the present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the art will understand that various modifications and equivalent other embodiments are possible therefrom. . Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

100: crucible assembly for manufacturing a cathode active material
110: first crucible
120: second crucible
OP: incision groove

Claims (8)

A first crucible having an open upper portion and a predetermined inner space; And
A second crucible disposed under the first crucible and having a cut groove having a preset open area disposed at an upper end of each sidewall; and
The open area of the cut groove is according to the following equation, a crucible assembly for manufacturing a positive electrode active material.
[Equation]

A _O : Open area of the incision groove
A _T : Area of the side wall of one second crucible delete The method of claim 1,
The incision groove is
A crucible assembly for manufacturing a positive electrode active material, which is disposed above the center of the height of the second crucible. The method of claim 1,
The second crucible is disposed so that the sidewalls face each other,
The incision groove is provided in plural, the crucible assembly for manufacturing a positive electrode active material, which is disposed to overlap each other on the sidewall. The method of claim 1,
At least one of the first crucible and the second crucible,
Crucible assembly for producing a positive electrode active material, formed of a compound represented by the following formula.
[Chemical Formula]
xAl ₂ O ₃ yMgO zSiO ₂
(0.9<x<1, 0<y<0.1, 0<z<0.1, x+y+z=1) The method of claim 1,
The second crucible is provided in plural, and stacked in a height direction under the first crucible, a crucible assembly for manufacturing a positive electrode active material. In a crucible for manufacturing a positive electrode active material having a predetermined internal space by a bottom and a side wall,
Includes; a cut-out groove disposed on the upper end of the side wall and having a preset open area,
The open area of the cut groove is a crucible for manufacturing a positive electrode active material according to the following equation.
[Equation]

A _O : Open area of the incision groove
A _T : area of one side wall The method of claim 7,
The crucible is a crucible for producing a cathode active material, which is formed of a compound represented by the following formula.
[Chemical Formula]
xAl ₂ O ₃ yMgO zSiO ₂
(0.9<x<1, 0<y<0.1, 0<z<0.1, x+y+z=1)

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