KR102246771B1 - Positive electrode material for lithium secondary battery and lithium secondary battery comprising positive electrode including nickel-based active material - Google Patents

Abstract

It is a secondary particle including a plurality of primary particles, the secondary particles include a radial arrangement structure and an irregular porous structure, and the radial arrangement structure is disposed closer to the surface of the secondary particles compared to the irregular porous structure Disclosed are a positive electrode active material for a lithium secondary battery including a nickel-based active material, wherein a lithium fluorine-based compound is present on the surface of the nickel-based active material, a method of manufacturing the same, and a lithium secondary battery including a positive electrode including the same.

Description

[Positive electrode material for lithium secondary battery and lithium secondary battery comprising positive electrode including nickel-based active material]

It relates to a lithium secondary battery including a positive electrode active material for a lithium secondary battery and a positive electrode including the same.

With the development of portable electronic devices and communication devices, there is a high need to develop lithium secondary batteries with high energy density.

Among the positive electrode active materials of lithium secondary batteries, nickel-based active materials are capable of realizing a high capacity, and thus research on this is actively being conducted. However, the reliability of a lithium battery using the nickel-based active material may be lowered due to unreacted residual lithium present on the surface, and thus improvement is required.

One aspect is to provide a cathode active material for a lithium secondary battery whose lifespan is improved by reducing the increase in resistance by suppressing the occurrence of cracks during charging and discharging with a small content of residual lithium.

Another aspect is to provide a lithium secondary battery with improved cell performance by including a positive electrode including the positive electrode active material described above.

It is a secondary particle including a plurality of primary particles according to one aspect,

The secondary particles include a radial array structure and an irregular porous structure,

The radial arrangement structure includes a nickel-based active material disposed closer to the surface of the secondary particles compared to the irregular porous structure,

A positive electrode active material for a lithium secondary battery in which a lithium fluorine-based compound is present is provided on the surface of the nickel-based active material.

According to another aspect, it contains secondary particles including an agglomerate of two or more primary particles, wherein the secondary particle has a long axis or a short axis of the (003) plane of the primary particle, and the (003) plane is the virtual maximum of the secondary particles. It includes a radial arrangement structure in which the primary particles are oriented so as to be in a direction perpendicular to a tangent line at a point where they meet an outline, and at least 50% of the secondary particles have the radial arrangement structure, and a lithium fluorine-based compound is formed on the surface of the secondary particles. An existing positive electrode active material for a lithium secondary battery is provided.

According to another aspect, there is provided a lithium secondary battery including a positive electrode, a negative electrode, and an electrolyte interposed therebetween including the above-described positive electrode active material.

In the cathode active material for a lithium secondary battery according to the present embodiment, the content of residual lithium is reduced. When a lithium secondary battery is manufactured using such a positive electrode active material, the amount of gas generated during storage at a high temperature is reduced, the rate of increase in the thickness of the cell is reduced, and capacity, efficiency, and life characteristics are improved.

1 is a schematic diagram showing a cross-sectional structure of a positive active material for a lithium secondary battery according to an embodiment of the present invention.
2 is a schematic diagram showing plate particles of a positive electrode active material according to an embodiment of the present invention.
3 is a schematic diagram for explaining the definition of a radial type in secondary particles of a positive electrode active material according to an embodiment of the present invention.
4 is a schematic view for explaining the structure of a positive electrode active material according to another embodiment of the present invention.
5 is a schematic diagram for explaining the orientation of primary particles in a positive electrode active material according to another embodiment of the present invention.
6 is a perspective view schematically showing the structure of a lithium secondary battery having a positive electrode including a positive electrode active material according to an embodiment of the present invention.
7 is a graph showing changes in battery thickness during high temperature storage in coin cells manufactured according to Preparation Example 1 and Comparative Preparation Example 1. FIG.

Hereinafter, an exemplary positive electrode active material for a lithium secondary battery, a method of manufacturing the same, a positive electrode for a lithium secondary battery including the same, and a lithium secondary battery having the same will be described in more detail below with reference to the accompanying drawings.

Hereinafter, a cathode active material according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. 1 is a schematic diagram schematically showing the structure of a positive electrode active material according to the present embodiment. 2 is a schematic diagram showing a positive electrode having the shape of a plate particle according to the present embodiment, and FIG. 3 is a view for explaining the definition of a radial shape in the secondary particles of the positive electrode active material according to the present embodiment.

The positive electrode active material for a lithium secondary battery according to the present embodiment includes a nickel-based active material 10 including a radial array structure 12 and an irregular porous structure 11 as shown in FIG. 1. The radial arrangement structure 12 may be located closer to the surface than the irregular porous structure 11. In addition, although not shown in FIG. 1, fluorine may exist on the surface of the nickel-based active material 10.

The positive electrode active material according to the present embodiment includes a nickel-based active material 10 having a radial array structure and an irregular porous structure at the same time, and increases initial efficiency and improves capacity as compared to a general positive electrode active material. In addition, when the positive electrode active material of the present embodiment is used in a battery, the amount of gas generated when stored at a high temperature can be effectively reduced and lifespan characteristics are improved.

Referring to FIG. 1, the nickel-based active material 10 of the present embodiment may include a plurality of primary particles 13, and the primary particles 13 may include plate particles.

Referring to FIG. 2, a length t of one axial direction (eg, a thickness direction) may be shorter than a long axis length a of the other direction (eg, a surface direction) of the plate particles. The plate particles may have a polygonal nanoplate shape such as a hexagon like A, a nanodisk shape like B, and a rectangular parallelepiped shape like C. The thickness t of the plate particles is smaller than the lengths a and b in the plane direction. The plate particles may be arranged such that the plate thickness surface is oriented toward the surface of the secondary particles. At this time, the crystal plane through which lithium can enter and exit is exposed on the surface of the secondary particles. The average length of the plate particles may be 150 nm to 500 nm, for example, 200 nm to 400 nm. The average length means the average length of the long side and the short side in the plane direction of the plate particle. The long side means the length of the longest side and the short side means the length of the shortest side. The average thickness of the plate particles is 100 nm to 200 nm. And the ratio of the average thickness and the average length is 1:2 to 1:10, for example 1:2 to 1:5.

The radial arrangement structure 12 means that the thickness direction of the primary particles is aligned so that the thickness direction of the secondary particles is perpendicular to or perpendicular to the center direction of the secondary particles and a direction of ±10°. At least 30% or more, for example, 50% or more of the primary particles may be aligned such that the thickness direction is perpendicular to the direction toward the center of the secondary particle or perpendicular to ±10° to form a radial arrangement structure. More specifically, referring to FIG. 3, it means that the thickness direction (t) of the plate particles is aligned to form a direction perpendicular to or perpendicular to the direction R from the secondary particle toward the center or ±10°. As such, the active material including the radial arrangement structure facilitates lithium diffusion and suppresses the occurrence of cracks by suppressing stress caused by volume changes during lithium charging and discharging. In addition, the surface resistance layer is reduced during manufacture, and the active surface area required for lithium diffusion can be made large by exposing a large amount of the lithium diffusion direction to the surface.

The irregular porous structure 11 means that the primary particles 13 are randomly arranged without a certain regularity. Specifically, plate particles may be randomly arranged without a certain regularity to form an irregular porous structure, and more specifically, at least 30% of the primary particles are arranged in a direction of ±10° to the center or the center of the secondary particles. It does not mean that it is randomly arranged. The irregular porous structure 11 may have a larger pore size than the radial arrangement structure 12.

The radial arrangement structure 12 may be located closer to the surface than the irregular porous structure 11. For example, the radial arrangement structure 12 may be located outside, and the irregular porous structure 11 may be located inside. Referring to Figure 1, the outer (a ₂ ) is from the outermost surface of the total distance (L) from the center to the surface of the nickel-based compound to a point corresponding to the length of 30 to 50%, for example, 40% of the length It can mean the area of. The inside (a ₁ ) may mean an area from the center to a point corresponding to 50 to 70 length% of L, for example, 60 length%.

The pore size of the inner (a ₁ ) is 150 nm to 1 μm, for example, 150 nm to 550 nm, for example, 200 nm to 500 nm, and the _{pore size of the outer (a 2} ) is less than 150 nm, for example, 100 nm or less, eg For example, it is 20nm to 90nm. In this way, the pore size of the inner (11) is _{large compared to the case of the outer (a 2} ), which has the advantage of shortening the lithium diffusion distance in secondary particles of the same size. It relieves volume change.

The term "pore size" refers to the average diameter of the pores when the pores are spherical or circular. When the pores have an elliptical structure, the pore size indicates the length of the major axis.

_{Closed pores may exist in the inside (a 1} ) of the nickel-based active material 10 and closed pores and/or open pores may exist in the outside (a2). Closed pores are difficult to contain electrolytes, while open pores may contain electrolytes or the like inside the pores. In the present specification, "closed pores" are independent pores in which all of the walls of the pores are formed in a closed structure and are not connected to other pores, and "open pores" are pores in which at least some of the walls of the pores are formed in an open structure and connected to the outside of the particle. It can be called continuous pore. The size of the open pores may be less than 150 nm, for example 10 nm to 100 nm, such as 25 nm to 145 nm.

The secondary particles may have a size of 2 μm to 20 μm, for example 3 μm to 14 μm, for example 8 μm to 10 μm. The size of the secondary particles may represent an average diameter when the shape is close to a circular shape.

The nickel-based active material 10 of the present embodiment may be represented by Formula 1 below.

[Formula 1]

Li _a (Ni _1-xyz Co _x Mn _y M _z ) O ₂

In Formula 1, M is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe ), copper (Cu), zirconium (Zr), and aluminum (Al), and 0.90≤a≤1.3, x≤(1-xyz), y≤(1-xyz), z≤( 1-xyz), 0<x<1, 0≤y<1, 0≤z<1. In Formula 1, 0.95≤a≤1.05, 0<x≤1/3, for example, 0.05≤x≤1/3, and 0≤y≤0.5, for example, 0.05≤y≤1/3, 0≤z≤ It may be 0.05, 1/3≤(1-xyz)≤0.95. In Formula 1, when 0<z≤0.05, M may be aluminum (Al).

The content of nickel in the nickel-based active material 10 is 0.3 mol% to 0.99 mol% based on the total content of transition metals (Ni, Co, Mn), and has a higher content than manganese content and cobalt content. . For example, the content of nickel may be in the range of 0.3 mol% to 0.6 mol%. The content of nickel in the nickel-based active material 10 is larger than that of each of the other transition metals, based on a total of 1 mole of the transition metal. As described above, when the nickel-based active material 10 having a large nickel content is used, a lithium secondary battery having a high lithium diffusivity, good conductivity, and a higher capacity at the same voltage can be manufactured. The nickel-based active material 10 is, for example, LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , or LiNi _0.85 Co _0.1 Al _0.05 O ₂ .

The porosity of the nickel-based active material 10 of the present embodiment may be 1% to 10%, for example, 1.5% to 8%. In the nickel-based active material, the external porosity may be smaller than the internal porosity. Specifically, the porosity of the inside may be 2% to 20%, and the porosity of the outside may be 0.1% to 5%. In the present specification, the term "porosity" refers to an area occupied by pores relative to the total total area as a ratio.

The fluorine may exist on the surface of the nickel-based active material 10 in the form of a lithium fluorine-based compound. The lithium fluorine-based compound may be a compound produced by reacting a fluorine compound with residual lithium present on the surface of the nickel-based active material. Specifically, the fluorine may be present on the surface of the nickel-based active material in the form of lithium fluoride (LiF). The lithium fluorine-based compound is produced by reacting surface residual lithium with a fluorine compound, and thus residual lithium may be reduced. By reducing the residual lithium, side reactions with the electrolyte can be reduced, and the life characteristics of the battery can be improved.

The lithium fluorine-based compound may exist in the form of a film or particle. In the present specification, the term "film" refers to a continuous or discontinuous coating film. The'particle' includes not only spherical but also amorphous. Fluorine of the lithium fluorine-based compound may be included in an amount of 0.01 to 1 part by weight based on 100 parts by weight of a nickel-based active material. When the content of fluorine is within the above range, the content of residual lithium in the nickel-based active material is reduced, thereby improving the reliability of a lithium secondary battery using the same.

Hereinafter, a cathode active material according to another embodiment of the present invention will be described with reference to FIG. 4. 4 is a schematic diagram for explaining the structure of a positive electrode active material according to another embodiment of the present invention. The positive electrode active material of the present embodiment includes substantially the same configuration as the positive electrode active material according to the exemplary embodiment of the present invention, except that it includes two or more primary particle structures and includes at least two or more radial centers. Therefore, a detailed description of substantially the same components will be omitted, and different components will be described. In the present specification, the term "radial center" refers to the center of a primary particulate structure including a porous internal structure and a radial arrangement structure.

The positive electrode active material of this embodiment includes at least one secondary particle including two or more primary particle structures, and the secondary particles include at least two or more radial centers. The nickel-based active material of the present embodiment can stably implement capacity characteristics compared to the nickel-based active material having the same composition, and has at least two radial centers to reduce the movement distance of lithium ions from the surface to the center, thereby reducing the utilization rate of lithium ions. Can be increased.

Referring to FIG. 4, the primary particle structure 41 includes a porous internal structure 41a and a radial arrangement structure 41b, and the secondary particle 42 includes at least two or more primary particle structures 41. The primary particle structure 41 is an aggregate formed by arranging two or more primary particles 41c. The primary particle structure 41 may be formed of a nickel-based active material. The radial array structure 41b may be positioned closer to the surface of the primary particle structure 41 than the porous internal structure 41a.

The porous internal structure 41a may have an irregular porous structure or a regular porous structure. The porous internal structure 41a may include plate particles, and in the case of having an irregular porous structure, the plate particles may be arranged without regularity.

The radial array structure 41b has a structure in which, for example, plate particles, which are primary particles 41c, are arranged in a radial array, as shown in FIG. 4. The meaning of the'radial array structure' is as described above.

The size of the primary particle structure 41 is 2 to 5 μm, for example, 3 to 4 μm, and the size of the nickel-based active material secondary particles 42 is 5 to 25 μm, for example, 5 to 22 μm, for example 7 to 20 μm, for example 9 to 15 μm.

In the primary particle structure 41, the porosity of the porous internal structure 41a is 5 to 15%, for example, 5 to 10%, and the porosity in the radial array structure 41b is 1 to 5%, for example 1 to 3%. When the porosity of the primary particle structure 41 is within the above-described range, a nickel-based active material having excellent capacity characteristics may be obtained.

According to an embodiment, the porosity of the radially arrayed structure 41b of the primary particulated structure 41 may be controlled to be smaller than that of the porous internal structure 41a. The pore size and porosity in the porous internal structure 41a may be larger and irregular than the pore size and porosity in the radial array structure 41b. When the porosity of the porous internal structure 41a and the radial arrangement 41b of the primary particle structure 41 meets the above-described range, the external density is increased compared to the internal, so that side reactions with the electrolyte can be effectively suppressed. have.

Closed pores may exist in the porous internal structure 41a of the primary particle structure 41, and closed pores and/or open pores may exist in the radial array structure 41b. While the closed pores are difficult to contain an electrolyte or the like, the open pores may contain an electrolyte or the like in the pores of the primary particle structure 41.

Hereinafter, a cathode active material according to another embodiment of the present invention will be described with reference to FIG. 5. 5 is a schematic diagram for explaining the orientation of primary particles in a positive electrode active material according to another embodiment of the present invention. The positive electrode active material according to the present embodiment includes substantially the same components as the positive electrode active material according to the exemplary embodiment of the present invention, except that the radial arrangement structure is different. Accordingly, a description will be given centering on a radial array structure, which is a different component, and detailed descriptions of substantially the same components will be omitted.

The positive electrode active material according to the present embodiment contains secondary particles including an aggregate of two or more primary particles. The secondary particles include a radial array structure in which the primary particles 50 are oriented so that the (003) plane of the primary particles 50 is in a direction perpendicular to the outermost surface (S) of the secondary particles, as shown in FIG. 5. . The outermost surface S may mean a surface connected along the outermost surface of the secondary particles. In addition, the vertical direction means that the (003) plane crosses the outermost surface (S) of the secondary particles while forming an angle of 90°±20°, for example, 90°±10°. In this case, 50% or more, for example, 60% or 70% or more of the secondary particles may have the radial arrangement structure. A lithium fluorine-based compound is present on the surface of the secondary particles. Due to the arrangement of the primary particles, the positive electrode active material according to the present embodiment has excellent lithium ion conductivity and a reduced surface resistance.

Hereinafter, a cathode active material according to another embodiment of the present invention will be described. In the above-described embodiments, a detailed description of substantially the same components will be omitted here, since they include substantially the same components except that the heterogeneous compound is disposed between the primary particles.

The positive electrode active material of the present embodiment includes secondary particles including an aggregate of two or more primary particles, and a heteroelement compound may be disposed between the primary particles. In the present specification, the term "between primary particles" includes grain boundaries of the primary particles and/or the surface of the primary particles. The positive electrode active material of the present exemplary embodiment includes a heterogeneous compound, so that lifespan characteristics and the like may be improved.

Heteroelement compounds are compounds containing heterogeneous elements, and at least one selected from zirconium (Zr), titanium (Ti), aluminum (Al), magnesium (Mg), tungsten (W), phosphorus (P) and boron (B) It may be a compound containing. The hetero-element compound may contain lithium (Li) and a hetero-element at the same time. The content of the heterogeneous element is 0.0005 to 0.1 mol, for example, 0.0001 to 0.03 mol, for example, 0.001 to 0.01 mol, based on 1 mol of the transition metal of the nickel-based active material.

Hereinafter, a method of manufacturing a nickel-based active material according to the present embodiment will be described.

First, it is possible to prepare secondary particles of a nickel-based active material by mixing a lithium raw material and a metal hydroxide at a predetermined molar ratio and performing a primary heat treatment at 600 to 900°C.

The metal hydroxide may be a compound represented by the following formula (2).

[Formula 2]

(Ni _1-xyz Co _x Mn _y M _z )(OH) ₂

In Formula 2, M is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe ), copper (Cu), zirconium (Zr), and aluminum (Al), and x≤(1-xyz), y≤(1-xyz), z≤(1-xyz), 0 <x<1, 0≤y<1, and 0≤z<1. In Formula 2, 0<x≦1/3, 0≦y≦0.5, 0≦z≦0.05, and 1/3≦(1-xyz)≦0.95. The metal hydroxide of Formula 2 is, for example, Ni _0.6 Co _0.2 Mn _0.2 (OH) ₂ , Ni _0.5 Co _0.2 Mn _0.3 (OH) ₂ , Ni _1/3 Co _1/3 Mn _1/3 (OH) ₂ Or Ni _0.8 Co _0.1 Mn _0.1 (OH) ₂ .

The lithium raw material is, for example, lithium hydroxide, lithium fluoride, lithium carbonate, or a mixture thereof. The mixing ratio of the lithium precursor and the metal hydroxide is controlled stoichiometrically so that the metal hydroxide of Formula 2 can be prepared.

The mixing may be dry mixing, and may be performed using a mixer or the like. Dry mixing can be done using milling. At this time, looking at the milling conditions, it is carried out so that there is little deformation such as micronization of the metal hydroxide used as a starting material. For this, it is necessary to control the size of the lithium precursor mixed with the metal hydroxide in advance. The size (average particle diameter) of the lithium precursor is in the range of 5 to 20 μm, for example about 10 μm. When the lithium precursor having such a size is milled with metal hydroxide at 300 rpm to 3,000 rpm, the desired nickel-based active material can be obtained. The term "average particle diameter" means D50, and the average particle diameter can be measured using, for example, a particle size analyzer (USA). In the above-described milling process, when the internal temperature of the mixer rises to 30°C or higher, a cooling process may be performed to maintain the internal temperature of the mixer in the room temperature (25°C) range. The size of the metal hydroxide is almost the same as the size of the nickel-based active material.

The primary heat treatment is carried out in an oxidizing gas atmosphere. The oxidizing gas atmosphere uses an oxidizing gas such as oxygen or air, for example, the oxidizing gas has a concentration of oxygen of 20% or more and an inert gas of less than 80%. It is appropriate to perform the first heat treatment in a range of not less than the crystallization temperature while the reaction between the lithium raw material and the metal precursor proceeds. Here, the crystallization temperature refers to a temperature at which crystallization is sufficiently achieved to realize a charging capacity that can be produced by the active material. The primary heat treatment is performed at 600 to 900°C, specifically 750 to 850°C, for example. The first heat treatment time varies depending on the heat treatment temperature and the like, but is performed for 2 to 20 hours, for example. The nickel-based active material secondary particles of the present embodiment may be manufactured by performing the first heat treatment under the above-described conditions. In the first heat treatment, boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper A metal compound including at least one selected from (Cu), zirconium (Zr), and aluminum (Al) may be further added. Such metal compounds include, for example, boric acid, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate, titanium oxide, vanadium oxide, chromium oxide, iron oxide, copper oxide, zirconium oxide and aluminum oxide. When the metal compound is added during the first heat treatment process, the metal compound may be doped into the nickel-based compound.

Subsequently, a fluoride precursor is added to the nickel-based active material secondary particles thus prepared to obtain a reaction mixture, and the reaction mixture is 300°C or more and less than 600°C, for example, 300 to 550°C, for example, 350 to 300°C in an oxidizing gas atmosphere. It goes through the process of secondary heat treatment at 500℃. In the case of performing the heat treatment within the above range, it may be advantageous to generate a surface fluorine compound while properly maintaining the size of the primary particles. Through the secondary heat treatment process, a lithium fluorine-based compound is formed on the surface of the nickel-based active material. Lithium of the lithium fluorine-based compound originates from residual lithium on the surface of the nickel-based active material. The secondary heat treatment time varies depending on the heat treatment temperature, but is carried out for, for example, 2 to 20 hours.

As the fluoride precursor, at least one selected from the group consisting of a fluorine-containing polymer and a metal fluoride may be used. The fluorine-containing polymer is, for example, at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and polytetrafluoroethylene. And metal fluoride, for example, _{MgF 2, MnF 2, LaF '} , BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2, AlF 3, ZrF 4, GaF 3, HfF 4, YbF _{3, ThF 3, ZnF 2 InF} 3, UF 3, YF 3, LaF 3, BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2. CuF ₂ , CoF ₂ , FeF ₂ , FeF ₃ , NiF ₂ . AlF ₃ , _{BaF 2} , CrF ₂ , MgF ₂ , MnF ₂ , MnF ₃ , FeF ₃ , CoF ₂ , NiF ₂ , CuF ₂ , NaF, TiF ₃ , ZnF ₂ and one or more selected from _{YF 3.} During the secondary heat treatment, a heteroelement compound containing at least one element selected from zirconium (Zr), titanium (Ti), aluminum (Al), magnesium (Mg), tungsten (W), phosphorus (P), and boron (B) More can be added. Such heteroelement compounds are, for example, titanium oxide, zirconium oxide (ZrO ₂ ), aluminum oxide (Al ₂ O ₃ ), magnesium oxide, tungsten chloride, monobasic ammonium phosphate, LiAlO ₂ , Li ₂ TiO ₃ , Li ₂ ZrO ₃ , LiBO ₃ , Li ₃ PO ₄ , and the like. In the above-described hetero-element compound, the content of the hetero-element is controlled to be 0.0005 to 0.03 mol, respectively, based on the total molar ratio of the transition metal of the secondary particles of the nickel-based active material and the hetero-element. When the heteroelement compound is added, it is present at one or more selected from the interface between the primary particles of the nickel-based active material and the surface of the primary particles. When the above-described heteroelement compound is added during the secondary heat treatment, it may be mixed and used without a solvent, but in some cases, a solvent may be used. Water, ethanol, or the like is used as a solvent. As described above, a compound containing at least one element selected from heterogeneous elements is interfacially coated on the secondary particles of the nickel-based active material on a per-primary particle basis to minimize surface exposure of the nickel-based active material when cracking occurs. The presence and distribution of a compound containing at least one element selected from among heterogeneous compounds can be confirmed through Electron Probe Micro-Analysis (EPMA) and Secondary Ion Mass Spectroscopy (Nano-SIMS). .

Metal hydroxide, which is a precursor of a nickel-based active material used in the method for manufacturing a positive electrode active material according to an embodiment of the present invention described above, may be prepared by the following method. According to the following method, it is possible to prepare a metal hydroxide having a radial arrangement and a porous plate particle. The method of preparing the metal hydroxide is not particularly limited, but, for example, a coprecipitation method, a solid phase method, or the like may be used. Hereinafter, a method of preparing the compound of Formula 2 as an example of a metal hydroxide according to the coprecipitation method will be described.

The nickel-based active material precursor according to the present embodiment may be prepared by stepwise changing process conditions such as the concentration and the amount of the metal raw material and the concentration and the amount of the aqueous ammonia as a complexing agent.

According to an embodiment, in the first step, the reaction is carried out by adding a complexing agent, a metal raw material, and a pH adjusting agent to the reactor. If the pH of the reaction mixture in the reactor changes as the reaction proceeds, a pH adjusting agent may be added as necessary to control the pH of the reaction mixture in a predetermined range.

Subsequently, the second step reaction is carried out by reducing the stirring power compared to the first step, and the third step reaction is carried out by increasing the concentration of the complexing agent than the second step.

The stirring power of the second and third steps is reduced compared to the stirring power of the first step. The stirring power of the second step and the third step may be the same. The stirring power in each step is in the range of ^{0.1 to 7 KW/m 2.}

The pH of the reaction mixture of the first step, the second step and the third step is controlled in the range of 10 to 12.

In the above-described method for preparing a nickel-based active material precursor, the concentration of the complexing agent increases sequentially as the first step, the second step, and the third step go on. The concentration of the complexing agent may range from 0.1 to 0.7M in the first to third steps, respectively. As the complexing agent, for example, aqueous ammonia is used.

In the first step, the pH of the reaction mixture is maintained and raw materials are added to form the core of the particles. In the second step, the amount and concentration of the metal raw material and the complexing agent are increased in order to prevent a decrease in the growth rate due to the growth of particles after reacting the product obtained from the first step for a certain period of time.

Subsequently, the amount and concentration of the metal raw material and the complexing agent are increased to prevent a decrease in the growth rate due to the growth of the particles after the reaction product obtained in the second step is reacted for a certain period of time. The porosity inside the nickel-based active material precursor particles is determined according to the time for applying each of the above-described steps.

In the nickel-based active material precursor according to an embodiment, the porous structure is affected by the input amount of the metal raw material, the concentration of the complexing agent, and the pH of the reaction mixture.

The pH adjuster controls the pH of the reaction mixture to form a precipitate from the reaction mixture, and examples include sodium hydroxide (NaOH), sodium carbonate (Na ₂ CO ₃ ), sodium oxalate (Na ₂ C ₂ O ₄ ), and the like. use. As a pH adjuster, sodium hydroxide (NaOH) is used, for example.

The complexing agent plays a role in controlling the reaction rate of formation of a precipitate in the coprecipitation reaction, and includes ammonium hydroxide (NH ₄ OH) (aqueous ammonia) and citric acid. The content of the complexing agent is used at a conventional level. As the complexing agent, for example, aqueous ammonia is used.

The concentration of the complexing agent is 0.1 to 0.7M, for example, may be about 0.2 to 0.5M. And the concentration of the metal raw material is 0.1 to 0.5M, for example 0.3M.

In the first step, the input amount of the metal raw material may be 50 to 100 ml/min. And the input amount of the complexing agent is 8 to 12 ml/min.

Subsequently, a metal raw material and a complexing agent are added to the reaction product of the first step, the pH of the reaction mixture is controlled, and a second step of performing the reaction is performed.

In the second step, the concentration of the complexing agent is, for example, 0.3 to 1.0 M, the input amount of the metal raw material in the second step is 90 to 120 ml/min, and the input amount of the complexing agent is 14 to 18 ml/min.

A nickel-based active material precursor is prepared including a third step of adding a metal raw material and a complexing agent to the reaction result of the second step, controlling the pH of the reaction mixture, and then performing the reaction.

In the third step, the concentration of the complexing agent may be 0.35 to 1.0M.

The reaction conditions in the third step have a great influence on the surface depth of the porous layer in the nickel-based active material precursor.

In the third step, the input amount of the metal raw material is 120 to 170 ml/min, and the input amount of the complexing agent is 19 to 22 ml/min.

In the manufacturing process, the metal precursor is used in consideration of the composition of the nickel-based active material precursor. Metal raw materials include metal carbonates, metal sulfates, metal nitrates, and metal chlorides.

If a compound represented by Formula 2 is to be prepared, a manganese precursor, a nickel precursor, and a cobalt precursor are used as metal raw materials. Manganese precursors, nickel precursors, and cobalt precursors include, for example, manganese sulfate, nickel sulfate, cobalt sulfate, manganese chloride, nickel chloride, and cobalt chloride.

Hereinafter, a method of manufacturing a lithium secondary battery having a positive electrode, a negative electrode, a non-aqueous electrolyte containing a lithium salt, and a separator including a nickel-based active material according to the present embodiment will be described.

The positive electrode and the negative electrode are prepared by coating and drying a composition for forming a positive electrode active material layer and a composition for forming a negative electrode active material layer on a current collector, respectively.

The composition for forming a positive electrode active material is prepared by mixing a positive electrode active material, a conductive agent, a binder, and a solvent, and the nickel-based active material according to the present embodiment is used as the positive electrode active material. As the nickel-based active material, a lithium composite oxide represented by Chemical Formula 1 may be used.

The binder is, for example, polyvinylidene fluoride, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, Polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butyrene rubber, fluorine rubber, and various copolymers.

Examples of the conductive agent include graphite such as natural graphite and artificial graphite; Carbon-based substances such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; Conductive fibers such as carbon fibers and metal fibers; Carbon fluoride; Metal powders such as aluminum and nickel powder; Conductive whiskey such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used.

As a non-limiting example of the solvent, N-methylpyrrolidone or the like is used.

The contents of the binder, the conductive agent, and the solvent are used at conventional levels.

The positive electrode current collector has a thickness of 3 to 500 μm, and is not particularly limited as long as it has high conductivity without causing chemical changes to the battery. For example, stainless steel, aluminum, nickel, titanium, heat-treated carbon, Alternatively, a surface-treated aluminum or stainless steel surface with carbon, nickel, titanium, silver, or the like may be used. The current collector may increase the adhesion of the positive electrode active material by forming fine irregularities on its surface, and various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics are possible.

Separately, a negative active material, a binder, a conductive agent, and a solvent are mixed to prepare a composition for forming a negative active material layer.

As the negative active material, a material capable of storing and releasing lithium ions is used. As a non-limiting example of the negative active material, a carbon-based material such as graphite and carbon, lithium metal, an alloy thereof, and a silicon oxide-based material may be used. According to this embodiment of the present invention, silicon oxide is used.

As a non-limiting example of the binder, the same type as the positive electrode may be used.

The conductive agent and the solvent may be made of the same type of material as in the manufacture of the positive electrode.

The negative electrode current collector is generally made to have a thickness of 3 to 500 µm. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes to the battery, for example, copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, the surface of copper or stainless steel. For the surface treatment with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloys, etc. may be used. In addition, like the positive electrode current collector, it is possible to enhance the bonding strength of the negative electrode active material by forming fine irregularities on the surface thereof, and it may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

As the negative electrode, it is also possible to use a negative electrode made of lithium metal or a lithium metal alloy. The lithium metal alloy includes a lithium metal and a metal/metalloid or an oxide thereof which can be alloyed with the lithium metal. Metals/metalloids that can be alloyed with lithium metals or oxides thereof include Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloys (wherein Y is an alkali metal, alkaline earth metal, group 13 to group 16 element, transition Metal, rare earth element or a combination element thereof, not Si), Sn-Y alloy (wherein Y is an alkali metal, alkaline earth metal, group 13 to 16 element, transition metal, rare earth element, or a combination element thereof, and Sn Is not), MnOx (0 <x≤2), and the like.

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, Ge, P, As, Sb, Bi, S, Se, It may be Te, Po, or a combination thereof. For example, the oxide of the metal/metalloid alloyable with the lithium metal may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0<x<2), and the like.

A separator is interposed between the positive electrode and the negative electrode manufactured according to the above process.

The separator has a pore diameter of 0.01 to 10 µm and a thickness of 5 to 300 µm. As specific examples, olefin-based polymers such as polypropylene and polyethylene; Alternatively, a sheet made of glass fiber or a nonwoven fabric is used. When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

The lithium salt-containing non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt. As the non-aqueous electrolyte, a non-aqueous electrolyte solution, an organic solid electrolyte, an inorganic solid electrolyte, or the like is used.

Examples of the non-aqueous electrolyte include, but are not limited to, N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2- Dimethoxyethane, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolane, N,N-formamide, N,N-dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate , Methyl acetate, phosphoric acid tryester, trimethoxy methane, dioxolane derivative, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ether , Methyl pyropionate, ethyl propionate, and other aprotic organic solvents may be used.

Examples of the organic solid electrolyte include, but are not limited to, polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphoric acid ester polymers, polyvinyl alcohol, polyvinylidene fluoride, and the like.

Examples of the inorganic solid electrolyte include, but are not limited to, Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI- LiOH, Li ₃ PO ₄ -Li ₂ S-SiS ₂ and the like may be used.

Lithium salt is a material that is soluble in the non-aqueous electrolyte, and non-limiting examples include, but are not limited to, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO _{2 , LiAsF 6, LiSbF 6, LiAlCl} 4, CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2) 2 NLi, (FSO 2) 2 NLi, lithium chloro borate, lower aliphatic carboxylic acid lithium, tetra Lithium phenyl borate, imide, and the like can be used.

6 is a schematic cross-sectional view showing a typical structure of a lithium secondary battery according to this embodiment of the present invention.

Referring to FIG. 6, the lithium secondary battery 61 includes a positive electrode 63, a negative electrode 62, and a separator 64. The positive electrode 63, the negative electrode 62, and the separator 64 described above are wound or folded to be accommodated in the battery case 65. Subsequently, an organic electrolyte is injected into the battery case 65 and sealed with a cap assembly 66 to complete the lithium secondary battery 61. The battery case 65 may be cylindrical, rectangular, thin-film, or the like. For example, the lithium secondary battery 61 may be a large thin film type battery. The lithium secondary battery 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 electrolyte, 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 secondary battery has excellent storage stability, life characteristics, and high rate characteristics at high temperatures, it can be used in an electric vehicle (EV). For example, it may be used in a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV).

It will be described in more detail through the following Examples and Comparative Examples. However, the examples are for illustrative purposes and are not limited thereto.

Preparation Example 1: Preparation of composite metal hydroxide

[Stage 1]

First, ammonia water having a concentration of 0.30M was added to the reactor. The reaction was started by adding a metal raw material and a complexing agent (aqueous ammonia) at a rate of 90 ml/min and 10 ml/min, respectively, at a stirring power of 1.5 kW/㎥ and a reaction temperature of 50°C. In order to maintain the pH at 10 to 11, the reaction was carried out for 6 hours while adding sodium hydroxide (NaOH). It was confirmed that the average size of the particles obtained as a result of the reaction was in the range of about 5.5 to 6.5 μm, and the second step was carried out as follows.

[Step 2]

The metal raw material and the complexing agent were added at a rate of 100 ml/min and 15 ml/min, respectively, while maintaining the reaction temperature of 50° C., so that the concentration of the complexing agent was maintained at 0.35 M. In order to maintain the pH at 10 to 11, NaOH was added and reacted for 6 hours. At this time, the stirring power was lowered to 1.0kW/㎥ and the reaction proceeded. It was confirmed that the average size of the product particles obtained by carrying out this reaction was 9 to 10 µm, and the third step was carried out as follows.

[Step 3]

The metal raw material and the complexing agent were added at a rate of 150 ml/min and 20 ml/min, respectively, while maintaining the reaction temperature of 50°C, so that the concentration of the complexing agent was maintained at 0.40M. In order to maintain the pH at 10 to 11, NaOH was added and reacted for 4 hours. At this time, the stirring power was maintained the same as in step 2.

The result of the reaction was washed with distilled water and dried in a hot air oven for 24 hours _{to obtain a composite metal hydroxide (Ni 0.6} Co _0.2 Mn _0.2 (OH) ₂ ), which is a radial and porous plate particle.

Example 1: Preparation of nickel-based active material secondary particles

The composite metal hydroxide (Ni _0.6 Co _0.2 Mn _0.2 (OH) _{2 ) obtained according to Preparation Example 1, and lithium hydroxide (LiOH H 2} O) having an average particle diameter of about 10 μm were mixed with a high speed mixer. The mixture was dry at 2,000 rpm using and the first heat treatment was performed at about 850° C. for 8 hours in an oxidizing atmosphere to obtain a nickel-based active material (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) secondary particles.

100 parts by weight of the secondary particles of the nickel-based active material and 0.2 parts by weight of polyvinylidene fluoride were mixed in a dry manner at 2,000 rpm using a high speed mixer to obtain a reaction mixture. The reaction mixture was subjected to secondary heat treatment at about 350° C. for 6 hours in an oxygen atmosphere to obtain nickel-based active material secondary particles.

Example 2: Preparation of nickel-based active material secondary particles

A nickel-based active material secondary particles were obtained in the same manner as in Example 1, except that the secondary heat treatment temperature was changed to 450°C.

Comparative Example 1: Preparation of nickel-based active material secondary particles

The composite metal hydroxide (Ni _0.6 Co _0.2 Mn _0.2 (OH) _{2 ) obtained according to Preparation Example 1 and lithium hydroxide (LiOH H 2} O) having an average particle diameter of about 10 μm were mixed with a high speed mixer. Using dry mixing at 2,000 rpm, and performing the primary heat treatment for 6 hours at about 800 ℃ in the firing furnace in an oxidizing atmosphere to obtain a nickel-based active material (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) secondary particles.

The nickel-based active material secondary particles were subjected to secondary heat treatment at about 850° C. for 6 hours in an oxygen atmosphere to obtain nickel-based active material secondary particles.

Comparative Example 2: Preparation of secondary particles of nickel-based active material

_{A nickel-based active material (LiNi 0.6} Co _0.2 Mn _0.2 O ₂ ) secondary particles were obtained in the same manner as in Comparative Example 1, except that the secondary heat treatment temperature was changed to 890°C.

Comparative Example 3: Preparation of nickel-based active material secondary particles

_{The composite metal hydroxide (Ni 0.6} Co _0.2 Mn _0.2 (OH) ₂ ) obtained according to Preparation Example 1, _{and lithium hydroxide (LiOH H 2} O) having an average particle diameter of about 10 μm were used in a high speed mixer. Using a dry mixture at 2,000 rpm, and subjected to the primary heat treatment for 6 hours at about 800 ℃ in an oxidizing atmosphere in the firing furnace to obtain a nickel-based active material (LiNi _0.6 Co _0.6 Mn _0.2 O ₂ ) secondary particles.

100 parts by weight of the secondary particles of the nickel-based active material and 0.2 parts by weight of polyvinylidene fluoride were mixed in a dry manner at 2,000 rpm using a high speed mixer to obtain a reaction mixture. The reaction mixture was subjected to secondary heat treatment at about 850° C. for 6 hours in an oxygen atmosphere to obtain nickel-based active material secondary particles.

The nickel-based active material obtained according to Comparative Example 3 had a high secondary heat treatment temperature, so that fluorine coating was not well formed.

Comparative Example 4: Preparation of secondary particles of nickel-based active material

Nickel was carried out in the same manner as in Comparative Example 3, except that the first heat treatment temperature was changed to about 850°C, polyvinylidene fluoride was not used during the second heat treatment, and the second heat treatment temperature was changed to about 350°C. Secondary particles of the system active material were obtained.

Production Example 1: Preparation of coin cell

A lithium secondary battery (coin cell) was prepared as follows using the _{nickel-based active material (LiNi 0.6} Co _0.2 Mn _0.2 O ₂ ) secondary particles obtained according to Example 1 as a positive electrode active material.

Nickel-based active material obtained according to Example 1 (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) A mixture of 96 g of secondary particles, 2 g of polyvinylidene fluoride, and 47 g of N-methylpyrrolidone as a solvent, and 2 g of carbon black as a conductive agent was removed using a mixer to prepare a uniformly dispersed slurry for forming a positive electrode active material layer. .

The slurry prepared according to the above process was coated on an aluminum foil using a doctor blade to form a thin electrode plate, dried at 135° C. for 3 hours or more, and then subjected to rolling and vacuum drying processes to produce a positive electrode.

A separator (thickness: about 16 μm) made of a porous polyethylene (PE) film was interposed between the positive electrode and the lithium metal counter electrode, and an electrolyte was injected to produce a 2032 type coin cell.

The electrolyte was a solution containing _{1.1M LiPF 6} dissolved in a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3:5.

Production Example 2: Preparation of coin cell

A coin cell was manufactured in the same manner as in Preparation Example 1, except that the nickel-based active material secondary particles obtained according to Example 2 were respectively used instead of the nickel-based active material secondary particles obtained according to Example 1.

Comparative Production Examples 1 to 4: Preparation of coin cell

A coin cell was manufactured in the same manner as in Preparation Example 1, except that the secondary particles obtained according to Comparative Example 1-4 were used instead of the nickel-based active material secondary particles obtained according to Example 1.

Evaluation Example 1: Evaluation of residual lithium content

Example 1, Example 2, Comparative Example 1. The content of residual lithium present on the surface of the positive electrode active materials prepared in Comparative Examples 3 and 4 was measured, and some of the results are shown in Table 1 below.

_{The surface residual lithium content was evaluated by measuring the Li content of LiCO 3} and LiOH remaining on the surface of the positive electrode active material by a wet method (or titration method).

For a specific measurement method, for example, reference may be made to the method disclosed in paragraph [0054] of Japanese Patent Laid-Open No. 2016-081903.

Residual lithium content [ppm] Comparative Example 1 1559 Comparative Example 3 1062 Comparative Example 4 1467 Example 1 906 Example 2 1045

As shown in Table 1, the positive electrode active materials of Examples 1 and 2 showed that the residual lithium content was reduced compared to Comparative Examples 1 and 3.

Evaluation Example 2: Charge/discharge characteristics (initial efficiency)

In the coin cells manufactured according to Production Example 1, Production Example 2, Comparative Production Example 2, and Comparative Production Example 3, constant current was charged at 25°C with a current of 0.1C rate until the voltage reached 4.30V (vs. Li). Then, while maintaining 4.30V in the constant voltage mode, cut-off was performed at a current of 0.05C rate. Subsequently, the discharge was performed at a constant current of 0.1 C rate until the voltage reached 3.0 V (vs. Li) during discharge (1 ^st cycle, formation cycle).

Initial charging and discharging efficiency was investigated in each coin cell, and the results are shown in Table 2 below. Initial charge efficiency (I.C.E) was measured according to Equation 1 below.

[Equation 1]

Initial charge/discharge efficiency[%]=[1 ^st cycle discharge capacity/1 ^st cycle charge capacity]×100

In addition, each coin cell was charged and discharged 50 times with a current of 1C rate at 45°C to investigate the ratio of the first discharge capacity to the 50th discharge capacity, and the results are shown in Table 2 below. Life was measured according to Equation 2 below.

[Equation 2]

45℃ Life [%]=[50 ^st cycle discharge capacity/1 ^st cycle discharge capacity]×100

division Charging capacity (mAh/g) Discharge capacity (mAh/g) I.C.E (%) 45℃ life[%] Production example 1 197.9 187.6 94.8 98 Production Example 2 198.1 186.2 94.0 99 Comparative Production Example 2 198.5 184.4 92.9 93 Comparative Production Example 3 196.9 177.4 90.1 95

Referring to Table 2, the coin cells of Preparation Examples 1 and 2 had improved initial charging and discharging efficiency compared to the cases of Comparative Preparation Examples 2 and 3. In addition, the coin cell of Production Example 1-2 was improved in lifespan at 45° C. compared to the coin cell of Comparative Production Examples 2 and 3.

Evaluation Example 3: Evaluation of reduction in gas generation during high temperature storage

The coin cells prepared according to Production Example 1 and Comparative Production Example 1 were stored at 60° C. for 13 days in a 4.4V overcharge state, and the thickness change was measured. In this test, the swelling result was obtained as the maximum thickness change (Δt) compared to the initial thickness, and the result is shown in FIG.

Referring to FIG. 7, it was found that the rate of increase in cell thickness after high temperature storage was reduced in the coin cell of Production Example 1 compared to the coin cell of Comparative Production Example 1.

Evaluation Example 4: Evaluation of porosity using scanning electron microscope analysis

Electron scanning microscopy analysis was performed on the nickel-based active material secondary particles obtained according to Examples 1 and 2. Magellan 400L (FEI company) was used as an electron scanning microscope. The sample cross section was pretreated by milling for 6kV, 150uA, 4hr using JEOL's CP2. And the electron scanning microscope analysis was carried out under the condition of 350V.

The porosity evaluation results are shown in Table 3 below.

division Porosity (%) Example 1 inside 10 Out 2 Example 2 inside 10 Out 2

In the above, the present embodiment has been described with reference to the drawings and embodiments, but this is only illustrative, and those of ordinary skill in the art can understand that various modifications and other equivalent implementations are possible therefrom. will be. Therefore, the scope of protection of the present invention should be determined by the appended claims.

61: lithium secondary battery 62: negative electrode
63: anode 64: separator
65: battery case 66: cap assembly

Claims (17)

It is a secondary particle including a plurality of primary particles, the secondary particles include a radial arrangement structure and an irregular porous structure, and the radial arrangement structure is disposed closer to the surface of the secondary particles compared to the irregular porous structure It contains a nickel-based active material, and a lithium fluorine-based compound is present on the surface of the nickel-based active material, the inner pore size of the secondary particle is 150nm to 1㎛, the outer pore size is less than 150nm is a cathode active material for a lithium secondary battery ,
The positive electrode active material is a product obtained by heat treatment of a reaction mixture obtained by adding a fluoride precursor to a nickel-based active material,
The fluorine of the lithium fluorine-based compound is contained in an amount of 0.12 to 1 part by weight based on 100 parts by weight of the nickel-based active material. The method of claim 1,
The secondary particles are aggregates of primary particles, and heteroelement compounds are included between the primary particles,
The hetero-element compound is a compound containing at least one element selected from zirconium (Zr), titanium (Ti), aluminum (Al), magnesium (Mg), tungsten (W), phosphorus (P), and boron (B); Or a compound containing at least one element selected from zirconium (Zr), titanium (Ti), aluminum (Al), magnesium (Mg), tungsten (W), phosphorus (P) and boron (B), and a compound containing lithium A cathode active material for lithium secondary batteries in which this is present. The method of claim 1,
The nickel-based active material includes plate particles, and a positive electrode active material for a lithium secondary battery in which a long axis of the plate particles is arranged in a radial direction. The method of claim 1,
The nickel-based active material is a cathode active material for a lithium secondary battery, which is an active material represented by the following Formula 1:
[Formula 1]
Li _a (Ni _1-xyz Co _x Mn _y M _z ) O ₂
In Formula 1, M is boron (B), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe ), copper (Cu), zirconium (Zr), and an element selected from the group consisting of aluminum (Al),
0.95≤a≤1.3, x≤(1-xyz), y≤(1-xyz), z≤(1-xyz), 0<x<1, 0≤y<1, 0≤z<1. It contains secondary particles including an aggregate of two or more primary particles, wherein the secondary particles are a radial arrangement in which the primary particles are oriented so that the (003) surface of the primary particles is in a direction perpendicular to the outermost surface of the secondary particles Structure, 50% or more of the primary particles are arranged in the radial arrangement structure, a lithium fluorine-based compound is present on the surface of the secondary particle, and the pore size inside the secondary particle is 150 nm to 1 μm, and the external Is a cathode active material for lithium secondary batteries with a pore size of less than 150 nm,
The positive electrode active material is a product obtained by heat treatment of a reaction mixture obtained by adding a fluoride precursor to a nickel-based active material,
The fluorine of the lithium fluorine-based compound is contained in an amount of 0.12 to 1 part by weight based on 100 parts by weight of the nickel-based active material. The cathode active material for a lithium secondary battery according to claim 1, wherein the fluoride precursor is at least one selected from the group consisting of a fluorine-containing polymer and a metal fluoride. The method of claim 6, wherein the fluorine-containing polymer is at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and polytetrafluoroethylene,
The metal fluoride is _{MgF 2, MnF 2, LaF '} , BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2, AlF 3, ZrF 4, GaF 3, HfF 4, YbF 3, ThF _{3, ZnF 2 InF 3, UF} 3, YF 3, LaF 3, BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2. CuF ₂ , CoF ₂ , FeF ₂ , FeF ₃ , NiF ₂ . AlF ₃ , _{BaF 2} , CrF ₂ , MgF ₂ , MnF ₂ , MnF ₃ , FeF ₃ , CoF ₂ , NiF ₂ , CuF ₂ , NaF, TiF ₃ , ZnF ₂ and YF _{3 A} cathode active material for a lithium secondary battery that is at least one selected from. The cathode active material for a lithium secondary battery according to claim 1, wherein in the product obtained by heat treatment of the reaction mixture obtained by adding a fluoride precursor to the nickel-based active material, the heat treatment is performed at 300°C or more and less than 600°C in an oxidizing gas atmosphere. The method of claim 1, wherein the positive electrode active material includes at least one secondary particle including two or more primary particle structures, and the primary particle structure includes a porous interior and an exterior including a radial arrangement structure, and the secondary particles Is a cathode active material for a lithium secondary battery comprising at least two or more radial centers. The cathode active material for a lithium secondary battery according to claim 9, wherein the size of the primary particle structure is 2 to 5 μm, and the size of the secondary particles is 5 to 25 μm. The cathode active material for a lithium secondary battery according to claim 9, wherein the porosity inside the porosity is 5 to 15%, and the porosity at the outside including a radial arrangement structure is 1 to 5%. It is a secondary particle including a plurality of primary particles, the secondary particles include a radial arrangement structure and an irregular porous structure, and the radial arrangement structure is disposed closer to the surface of the secondary particles compared to the irregular porous structure A lithium fluorine-based compound is present on the surface of the nickel-based active material, and the secondary particle has a pore size of 150 nm to 1 μm, and an external pore size of less than 150 nm. ,
Fluorine of the lithium fluorine-based compound is contained in an amount of 0.01 to 1 parts by weight based on 100 parts by weight of the nickel-based active material,
The positive electrode active material includes at least one secondary particle including two or more primary particle structures, the primary particle structure includes a porous interior and an exterior including a radial array structure, and the secondary particles are at least two or more radial A cathode active material for lithium secondary batteries containing a center. The cathode active material for a lithium secondary battery according to claim 12, wherein the size of the primary particle structure is 2 to 5 μm, and the size of the secondary particles is 5 to 25 μm. The cathode active material for a lithium secondary battery according to claim 12, wherein the porosity inside the porosity is 5 to 15%, and the porosity at the outside including a radial arrangement structure is 1 to 5%. The cathode active material of claim 12, wherein the fluorine of the lithium fluorine-based compound is contained in an amount of 0.12 to 1 part by weight based on 100 parts by weight of the nickel-based active material. The method of claim 12, wherein the positive electrode active material is a product obtained by heat treatment of a reaction mixture obtained by adding a fluoride precursor to a nickel-based active material,
The fluoride precursor is at least one selected from the group consisting of a fluorine-containing polymer and a metal fluoride,
The fluorine-containing polymer is at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and polytetrafluoroethylene,
The metal fluoride is _{MgF 2, MnF 2, LaF '} , BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2, AlF 3, ZrF 4, GaF 3, HfF 4, YbF 3, ThF _{3, ZnF 2 InF 3, UF} 3, YF 3, LaF 3, BiF 3, PbF 2, KF, CaF 2, BaF 2, SnF 2, SrF 2. CuF ₂ , CoF ₂ , FeF ₂ , FeF ₃ , NiF ₂ . AlF ₃ , _{BaF 2} , CrF ₂ , MgF ₂ , MnF ₂ , MnF ₃ , FeF ₃ , CoF ₂ , NiF ₂ , CuF ₂ , NaF, TiF ₃ , ZnF ₂ and YF _{3 A} cathode active material for a lithium secondary battery that is at least one selected from. A lithium secondary battery comprising a positive electrode, a negative electrode, and an electrolyte interposed therebetween comprising the positive electrode active material of any one of claims 1 to 16.

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