Positive electrode active material precursor for lithium secondary battery, method for preparing positive electrode active material using same, and lithium secondary battery comprising positive electrode

Abstract

The present embodiment relates to a positive electrode active material precursor for a lithium secondary battery, a method for preparing a positive electrode active material for a lithium secondary battery using the same, and a lithium secondary battery using the positive electrode active material prepared by the same. The positive electrode active material precursor for a lithium secondary battery according to an embodiment may have a full width at half maximum (FWHM) (200) of a (200) plane diffraction peak obtained by X-ray diffraction in the range of 0.28 DEG to 1.30 DEG.

Description

Technical Field

[0001] The present embodiment relates to a positive electrode active material precursor for a lithium secondary battery, a method for preparing a positive electrode active material using the precursor, and a lithium secondary battery comprising the positive electrode active material prepared using the precursor. Background Art

[0002] As the positive electrode active material of the lithium secondary battery, lithium composite metal compounds and the like can be used. These positive electrode active materials can be produced by calcining powdered raw materials at high temperatures.

[0003] The firing process for the positive electrode active material involves heat treatment at high temperatures for a specific period of time in an atmosphere containing oxygen at or above a certain concentration. Optimizing the firing temperature and holding time is crucial to reduce process costs.

[0004] When preparing positive electrode active materials, production efficiency can be improved by increasing the filling amount in a saggar, but if the filling amount is too high, the unreacted residual lithium content will increase and the electrochemical characteristics will drop sharply due to the instability of the layered structure. Summary of the Invention

[0005] Technical issues

[0006] In this embodiment, the present invention aims to provide a positive electrode active material precursor for lithium secondary batteries that can minimize the manufacturing cost of positive electrode active materials while ensuring excellent electrochemical properties, as well as a method for preparing positive electrode active materials using the precursor, and a lithium secondary battery containing the positive electrode active materials prepared thereby.

[0007] Technical Solution

[0008] According to an embodiment of the positive electrode active material precursor for a lithium secondary battery, the full width at half maximum (FWHM) (200) of the (200) plane diffraction peak obtained by X-ray diffraction may be in the range of 0.28° to 1.30°.

[0009] According to one embodiment, a method for preparing a positive electrode active material for a lithium secondary battery includes: preparing a metal hydroxide containing nickel, cobalt and manganese; performing a first firing on a mixture of the metal hydroxide and a dopant to obtain a metal oxide precursor; preparing a molded body using the mixture of the metal oxide precursor and a lithium raw material; filling the molded body into a sagger and then performing a second firing to prepare a fired body; and crushing and classifying the fired body.

[0010] According to one embodiment, a positive electrode for a lithium secondary battery includes: a current collector; and a positive electrode active material layer located on at least one side of the current collector and containing the positive electrode active material.

[0011] A lithium secondary battery according to an embodiment may include the positive electrode.

[0012] Technical Effects

[0013] According to this embodiment, a positive electrode active material for lithium secondary batteries ensuring excellent electrochemical performance can be achieved by preparing a molded body using a metal oxide precursor in which hydroxide is converted into an oxide by a first heat treatment and then performing a sintering process to prepare a positive electrode active material.

[0014] In addition, by increasing the filling amount in the saggar during the firing process, the preparation cost of the positive electrode active material can be minimized, thereby significantly improving economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The SEM analysis results of the positive electrode active material precursor of Example 1 were measured at a magnification of 15,000 times.

[0016] Figure 2 The SEM analysis results of the positive electrode active material precursor of Comparative Example 2 were measured at a magnification of 15,000 times.

[0017] Figure 3 The SEM analysis results of the positive electrode active material precursor of Comparative Example 3 were measured at a magnification of 15,000 times. DETAILED DESCRIPTION

[0018] The terms "first," "second," and "third" are used to describe various parts, components, regions, layers, and / or segments, but these parts, components, regions, layers, and / or segments should not be limited by these terms. These terms are only used to distinguish one part, component, region, layer, and / or segment from another part, component, region, layer, and / or segment. Therefore, a first part, component, region, layer, and / or segment described below could also be described as a second part, component, region, layer, and / or segment without departing from the scope of the present invention.

[0019] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular form used is intended to include the plural form. It should also be understood that the term "comprising" as used in this specification may specifically refer to a certain characteristic, field, integer, step, action, element and / or component, but does not exclude the presence or addition of other characteristics, fields, integers, steps, actions, elements and / or components.

[0020] If a part is described as being "on" another part, it can be directly on the other part or there can be other parts therebetween. When a part is described as being "directly on" another part, there can be no other parts therebetween.

[0021] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Dictionary-defined terms should be interpreted as having the same meaning as that in the relevant technical literature and disclosed herein, and should not be interpreted in an idealized or overly formal sense.

[0022] In addition, unless otherwise specified, % means % by weight, and 1 ppm is 0.0001 % by weight.

[0023] The embodiments of the present invention will be described in detail below so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various forms and is not limited to the embodiments described herein.

[0024] Each embodiment is described in detail below.

[0025] According to one embodiment of the positive electrode active material precursor for a lithium secondary battery, the full width at half maximum (FWHM) (200) of the (200) plane diffraction peak obtained by X-ray diffraction can be in the range of 0.28° to 1.30°, more specifically in the range of 0.28° to 1.15°. Furthermore, the grain size of the positive electrode active material precursor can be in the range of 23 nm to 95 nm, more specifically in the range of 25 nm to 65 nm.

[0026] When the full width at half maximum of the (200) plane and the grain size meet the above ranges, the packing density can be increased in the preparation process, thereby improving the productivity of the positive electrode active material.

[0027] The specific surface area (BET) of the positive electrode active material precursor can be 20m 2 / g to 80m 2 / g range, more specifically 20m 2 / g to 60m 2 When the specific surface area satisfies the above range, excessive pores will not be formed in the positive electrode active material precursor. Therefore, when the positive electrode active material prepared using the same is used in a battery, side reactions with the electrolyte can be suppressed, thereby having excellent electrochemical properties.

[0028] The tap density of the positive electrode active material precursor may be 1.9 g / cc to 2.3 g / cc. When the tap density satisfies the above range, a positive electrode active material with excellent electrochemical properties such as lifespan and resistance characteristics can be achieved.

[0029] The average particle size (D50) of the positive active material precursor may be 2 μm to 7 μm, more specifically 3 μm to 6 μm. When the average particle size satisfies the above range, excellent electrochemical performance can be achieved due to the accelerated lithium diffusion rate.

[0030] The metal oxide may be represented by the following Chemical Formula 1.

[0031] [Chemical Formula 1]

[0032] Li a [Ni x Co y M1 z1 M2 z2 ]O2

[0033] In Chemical Formula 1, M1 is Mn or Al, and M2 is at least one of Al, Mg, Ti, Nb, W, Sc, Zr, Si, V, Fe, Y, Mo, or a combination thereof.

[0034] In the chemical formula 1, lithium may be included in an amount corresponding to a, ie, 0.8≤a≤1.2.

[0035] When a is too small, the capacity will decrease. When a is too large, the strength of the positive electrode active material will increase after firing, and the difficulty of crushing will increase. At the same time, the increase in lithium by-products will lead to an increase in gas production.

[0036] Considering the effect of controlling the lithium content on improving the capacity characteristics of the positive electrode active material and the firing balance during the preparation of the active material, it is more preferable to contain lithium in an amount of 0.9≤a≤1.1.

[0037] In the above chemical formula 1, nickel may include a content corresponding to x, that is, 0.8≤x<1. When x is greater than 0.8 and is large enough, it is possible to ensure that a sufficient amount of nickel contributes to charging and discharging, thereby achieving high capacity. More specifically, it can be 0.87≤x<1. When the nickel content satisfies the above range, a positive electrode active material with high output characteristics can be achieved. In addition, when the nickel content is greater than 0.87 mol, since the positive electrode active material prepared therefrom has a higher volume energy density, it is possible to increase the battery capacity and is also suitable for electric vehicles.

[0038] In the above Chemical Formula 1, cobalt may include a content corresponding to y, ie, 0 <y≤0.2。

[0039] Cobalt can improve the capacity and life of the battery. More specifically, the cobalt content can be 0.01≤y≤0.1.

[0040] In the above Chemical Formula 1, manganese may include a content corresponding to z1, ie, 0 <z1≤0.2。

[0041] Manganese can improve the stability of the positive electrode active material, thereby improving the stability of the battery. More specifically, the manganese content can be 0.01≤y≤0.1.

[0042] In the above Chemical Formula 1, M2 is a doping element. The doping element M2 may have a content corresponding to z2, that is, 0≤z2≤0.2.

[0043] For positive electrode active materials, the selection of doping elements is crucial to ensuring their lifespan and various electrochemical properties. In this embodiment, the properties of the positive electrode active material can be improved by applying various doping elements as described above. More specifically, the content of the doping elements can be 0.001 ≤ y ≤ 0.08.

[0044] According to one embodiment, a method for preparing a positive electrode active material for a lithium secondary battery includes: a step of preparing a metal hydroxide containing nickel, cobalt and manganese; a step of performing a first firing on a mixture of the metal hydroxide and a dopant to obtain a metal oxide precursor; a step of preparing a molded body using the mixture of the metal oxide precursor and a lithium raw material; a step of filling the molded body into a sagger and then performing a second firing to prepare a fired body; and a step of crushing and classifying the fired body.

[0045] First, a metal hydroxide containing nickel, cobalt, and manganese is prepared.

[0046] The metal hydroxide can be prepared by conventional methods known in the art, such as solid phase reaction method, coprecipitation method, sol-gel method, hydrothermal synthesis method, etc.

[0047] For example, in the coprecipitation method, a metal salt aqueous solution containing a nickel raw material, a cobalt raw material, a manganese raw material and water is prepared, and then the metal salt aqueous solution is supplied to a precipitation reactor to obtain a metal hydroxide.

[0048] Next, the mixture obtained by mixing the metal hydroxide and the dopant is subjected to a first firing to prepare a metal oxide precursor.

[0049] The dopant is at least one of an oxide or hydroxide, a nitrate, and a combination thereof of at least one of Zr, Ti, W, Al, Mg, V, Co, and Ni.

[0050] Furthermore, the first firing may be performed for 1 to 10 hours at 310° C. to 590° C. or 350° C. to 550° C. If the temperature and time conditions of the first firing meet the above ranges, the packing density described below can be ensured.

[0051] The physical properties of the metal oxide precursor, ie, full width at half maximum, grain size, specific surface area, tap density, average particle size, etc., are the same as those described above, and therefore will not be described in detail here.

[0052] Then, a step of preparing a molded body by using the mixture of the metal oxide precursor and the lithium raw material is performed.

[0053] The mixture may be prepared such that a molar ratio (Li / Me) of lithium (Li) to all metals (Me) other than lithium is in the range of 1.0 to 1.1, or in the range of 1.01 to 1.08.

[0054] The molded body can be prepared using at least one of a disk pelletizer, an intensive mixer, a briquetting machine, a press, a spray dryer, and an extruder.

[0055] The packing density of the prepared shaped body may be in the range of 1.0 g / cc to 2.5 g / cc.

[0056] When the packing density satisfies the above range, the filling amount in the sagger can be increased during the firing process, thereby ultimately improving the productivity of the positive electrode active material.

[0057] Subsequently, a step of filling the molded body into a sagger and then performing a second firing to prepare a fired body is performed.

[0058] The second firing process may be performed at 850° C. to 950° C. for 10 hours to 30 hours.

[0059] When the temperature and time conditions of the second firing meet the above ranges, the structural stability of the layered positive electrode active material can be improved by reducing the occurrence of cation mixing. The improved structural stability has the advantage of reducing lifespan, output power and resistance.

[0060] Next, by pulverizing and classifying the fired body, the positive electrode active material for the lithium secondary battery according to this embodiment can be obtained.

[0061] In one embodiment, a positive electrode is provided, including a current collector and a positive electrode active material layer located on one side of the current collector and containing the positive electrode active material prepared according to the above embodiment.

[0062] The characteristics of the positive electrode active material constituting the positive electrode active material layer are the same as those described above, and therefore, a detailed description of the positive electrode active material is omitted.

[0063] The current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, or the like.

[0064] Meanwhile, the positive active material layer may include a binder and a conductive agent.

[0065] At this time, the binder plays a role in enhancing the adhesion between the positive electrode active material particles and the bonding force between the positive electrode active material and the positive electrode collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, sodium carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber or its various copolymers, etc., one of which can be used alone or in combination of two or more, but not limited thereto. The binder can account for 1 to 30 weight % of the total weight of the positive electrode active material layer.

[0066] Furthermore, the conductive material is used to impart conductivity to the electrode. In the assembled battery, any material can be used without particular limitation as long as it exhibits electronic conductivity and does not cause chemical changes. Specific examples include graphites such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, summer black, and carbon fiber; metal powders or fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polystyrene derivatives. These materials can be used alone or in combination of two or more, but are not limited thereto. The conductive material is typically included in an amount of 1 to 30% by weight of the total weight of the positive electrode active material layer.

[0067] When the positive electrode active material is used, the positive electrode can be prepared according to a conventional positive electrode preparation method.

[0068] Specifically, the positive electrode is formed by coating the positive electrode active material and, as needed, a positive electrode active material layer-forming composition optionally containing a binder, a conductive material, or a solvent on a positive electrode current collector, followed by drying and rolling. In this case, the types and contents of the positive electrode active material, binder, and conductive material are as described above.

[0069] The solvent can be a solvent commonly used in the relevant technical field, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone or water. These solvents can be used alone or in combination of two or more. The amount of the solvent should take into account the coating thickness and preparation yield of the slurry to dissolve or disperse the positive electrode active material, conductive agent and binder, and to achieve the viscosity required for excellent thickness uniformity of the coating used for subsequent positive electrode preparation.

[0070] In another method, the composition for preparing the positive electrode active material layer is cast on an independent support, and then peeled from the support to obtain a thin film, which is then laminated on a positive electrode collector to prepare a positive electrode.

[0071] In one embodiment, a lithium secondary battery including the positive electrode is provided.

[0072] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, a separator disposed between the positive and negative electrodes, and an electrolyte, wherein the positive electrode is as described above. Furthermore, the lithium secondary battery may optionally include a battery container for accommodating the electrode assembly including the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0073] In the lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0074] The negative electrode current collector is not particularly limited to a specific material, as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface treated with carbon, nickel, titanium, silver, or the like, or aluminum-cadmium alloys can be used. Furthermore, the negative electrode current collector typically has a thickness of 3 to 500 microns. Similar to the positive electrode current collector, microscopic irregularities can be formed on the collector surface to enhance the binding force of the negative electrode active material. For example, various forms such as films, sheets, foils, meshes, porous bodies, foams, and non-woven fabrics can be used.

[0075] The negative electrode active material layer may optionally contain a negative electrode active material, a binder, and a conductive agent. As an example, the negative electrode active material layer may be prepared by coating a composition for forming a negative electrode active material layer containing a negative electrode active material and optionally containing a binder and a conductive agent on a negative electrode current collector and drying the coating, or by casting the negative electrode active material layer on a separate support, peeling the resulting film from the support, and laminating the film on the negative electrode current collector.

[0076] The negative electrode active material can use compounds that can reversibly intercalate and deintercalate lithium. Specific examples include carbonaceous materials such as synthetic graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metal compounds that can alloy with lithium, such as silicon, aluminum, tin, lead, zinc, bismuth, indium, magnesium, gallium, cadmium, silicon alloys, tin alloys, or aluminum alloys; and metal compounds such as SiO β (0<β<2), metal oxides capable of lithium insertion and extraction, such as SnO2, vanadium oxide, lithium vanadium oxide, etc.; or composites including the metal compound and carbonaceous materials, such as Si-C complex or Sn-C complex, etc., any single material or a mixture of two or more of these can be used. In addition, as the negative electrode active material, a metallic lithium film can also be used. In addition, carbon materials can use low-crystalline carbon and high-crystalline carbon, etc. As low-crystalline carbon, soft carbon and hard carbon are representative; as high-crystalline carbon, it includes amorphous, flaky, needle-shaped, spherical or fibrous natural graphite or synthetic graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch-based carbon fibers, mesoporous carbon microspheres, liquid crystal pitch and high-temperature fired carbon such as petroleum and coal tar-based coke.

[0077] The binder and the conductive agent may be the same as those described above for the positive electrode.

[0078] Next, depending on the type of lithium secondary battery, a separator may be present between the positive electrode and the negative electrode.

[0079] These separators may be made of polyethylene, polypropylene, polyvinylidene fluoride, or two or more layers thereof, and may also be mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators.

[0080] In addition, in the lithium secondary battery, as the electrolyte, organic solvent electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc. that can be used when preparing lithium secondary batteries can be used, but are not limited thereto.

[0081] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0082] The organic solvent can be used without special restrictions, as long as it can serve as a medium for the migration of ions in the electrochemical reaction of the battery. Specifically, the organic solvent can use the following substances. Ester solvents, such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, etc.; ether solvents, such as dibutyl ether or tetrahydrofuran, etc.; ketone solvents, such as cyclohexanone, etc.; aromatic hydrocarbon solvents, such as benzene, fluorobenzene, etc.; carbonate solvents, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (EPC), etc. carbonate, PC), etc.; alcohol solvents such as ethanol and isopropanol; nitriles such as R-CN (wherein R is a linear, branched or cyclic hydrocarbon group of C2 to C20, which may contain a double bond, an aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among them, carbonate solvents are preferred, and more preferably a mixture of a cyclic carbonate (such as ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery and a low-viscosity chain carbonate compound (such as ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate). In this case, mixing the cyclic carbonate and the chain carbonate in a volume ratio of about 1:1 to about 1:9 can make the performance of the electrolyte excellent.

[0083] The lithium salt can be used without special restrictions as long as it is a compound that can provide lithium ions used in lithium secondary batteries. Specifically, the lithium salt includes LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is recommended to be used in the range of 0.1 to 2.0M. When the concentration of the lithium salt is within the range, the electrolyte has appropriate conductivity and viscosity, so that excellent electrolyte performance can be exhibited, and lithium ions can be effectively migrated.

[0084] As described above, lithium secondary batteries containing the positive electrode active material according to the present invention exhibit excellent discharge capacity, output characteristics, and capacity retention, and are therefore very useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as electric vehicles such as hybrid electric vehicles (HEVs).

[0085] Embodiments of the invention

[0086] The following will describe embodiments of the present invention in detail. However, this is provided as an example only, and the present invention is not limited thereto, and the present invention is only limited by the scope of the following claims.

[0087] Example 1

[0088] (1) Preparation of metal oxide precursors

[0089] The precursor was prepared by a general co-precipitation method.

[0090] Specifically, the nickel raw material is NiSO4·6H2O, the cobalt raw material is CoSO4·7H2O, and the manganese raw material is MnSO4·H2O. These raw materials are dissolved in distilled water to prepare a metal salt aqueous solution.

[0091] After the coprecipitation reactor was prepared, nitrogen was purged into the reactor to prevent oxidation of metal ions during the coprecipitation process, and the reactor temperature was maintained at 50°C.

[0092] A complexing agent, NH4OH, was added to the coprecipitation reactor, and NaOH was used to adjust the pH. According to the coprecipitation process, the obtained precipitate was filtered, washed with distilled water, and dried in an oven at 100° C. for 24 hours to prepare a positive electrode active material precursor.

[0093] The composition of the prepared precursor is (Ni 0.96 Co 0.03Mn 0.01 )(OH)2.

[0094] The mixture of the metal hydroxide and ZrO2 as a doping agent is placed in a sagger made of mullite, and placed in a firing furnace in an oxygen atmosphere for a first firing at 500° C. to obtain a metal oxide precursor.

[0095] (2) Preparation of positive electrode active material

[0096] The precursor prepared in (1) was mixed with a lithium ion (LiOH) raw material and water. The resulting mixture was placed in a disc pelletizer to form spherical bodies having an average diameter of 3 mm. At this time, the molar ratio of lithium (Li) to total metal (Me) (Li / Me) was 1.05.

[0097] The molded body is filled into a mullite sagger, placed in a firing furnace in an oxygen atmosphere, and subjected to a second firing at 900° C. The material after the second firing is crushed and classified to prepare a positive electrode active material for a lithium secondary battery.

[0098] Example 2

[0099] (1) Preparation of metal oxide precursors

[0100] A metal oxide precursor was prepared in the same manner as in Example 1, except that the first firing temperature was changed to 350°C.

[0101] (2) Preparation of positive electrode active material

[0102] A positive electrode active material for a lithium secondary battery was prepared using the same method as in Example 1.

[0103] Example 3

[0104] (1) Preparation of metal oxide precursors

[0105] A metal oxide precursor was prepared in the same manner as in Example 1, except that the first firing temperature was changed to 550°C.

[0106] (2) Preparation of positive electrode active material

[0107] A positive electrode active material for a lithium secondary battery was prepared using the same method as in Example 1.

[0108] Comparative Example 1

[0109] (1) Preparation of metal oxide precursors

[0110] The metal oxide precursor was prepared by the same method as in Example 1.

[0111] (2) Preparation of positive electrode active material

[0112] The precursor prepared in (1), the dopant ZrO2, and the LiOH lithium raw material are mixed, the resulting mixture is filled into a sagger, and placed in a firing furnace in an oxygen atmosphere and fired at 900°C. The fired material is crushed and classified to prepare a positive electrode active material for a lithium secondary battery.

[0113] Comparative Example 2

[0114] A metal oxide precursor was prepared in the same manner as in Example 1, except that the first firing temperature was changed to 300°C.

[0115] (2) Preparation of positive electrode active material

[0116] A positive electrode active material for a lithium secondary battery was prepared using the same method as in Example 1.

[0117] Comparative Example 3

[0118] A metal oxide precursor was prepared in the same manner as in Example 1, except that the first firing temperature was changed to 600°C.

[0119] (2) Preparation of positive electrode active material

[0120] A positive electrode active material for a lithium secondary battery was prepared using the same method as in Example 1.

[0121] Experimental Example 1 - Measuring Filling Density

[0122] In Example 1, the packing density of the molded body prepared using a disc pelletizer and the mixture of the precursor, additive, and lithium raw material in Comparative Example 1 was measured to prepare a positive electrode active material. The results are shown in Table 1 below.

[0123]

Table 1

[0124] distinguish Filling density (g / cc) Experimental Example 1 1.2 Comparative Example 1 0.8

[0125] As shown in Table 1, the packing density of the molded body prepared in Example 1 is more than 1.5 times higher than that of the mixture prepared in Comparative Example 1. This shows that the use of the positive electrode active material in Example 1 can increase the charge capacity per firing, thereby improving firing productivity.

[0126] Experimental Example 2-Life Characteristics Measurement

[0127] (1) Production of button-type half-cell

[0128] CR2032 button batteries were manufactured using the positive electrode active materials prepared in the experimental examples and comparative examples, and electrochemical tests were performed.

[0129] Specifically, a positive electrode active material, a conductive agent (carbon black), and a polyvinylidene fluoride binder (trade name: KF1120) were mixed in a weight ratio of 96:2:2, and the mixture was added to an N-methyl-2-pyrrolidone solvent to a solid content of about 30 wt %, thereby preparing a positive electrode active material slurry.

[0130] The slurry was applied to an aluminum foil (Al foil, thickness: 15 μm) as a positive electrode current collector using a doctor blade, dried in a vacuum at 120° C. for 5 hours, and then rolled to produce a positive electrode.

[0131] A 2032 coin-type half-cell was fabricated using the aforementioned positive electrode, a lithium metal negative electrode (300 μm thick, MTI), an electrolyte, and a polypropylene separator according to conventional methods. The electrolyte was prepared by dissolving 1 M LiPF6 in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate, and ethyl methyl carbonate (EMC) (the mixing ratio, by volume, was EC:DMC:EMC = 3:4:3).

[0132] The prepared coin-type half-cells were aged at room temperature for 12 h, and then their electrochemical performance was measured.

[0133] (2) XRD measurement (FWHM and grain size measurement)

[0134] The positive electrode active materials prepared in the examples and comparative examples were subjected to Cu Kα ray X-ray diffraction analysis was performed using X'pert pro (PANalytical). The results are shown in Table 2 below.

[0135] The full width at half maximum (FWHM) (200) refers to the full width at half maximum corresponding to the (200) plane (the peak at approximately 43-44° 2θ).

[0136] In addition, the grain size was measured using the same equipment.

[0137] (3) Discharge capacity evaluation

[0138] Capacity evaluation was performed using a base capacity of 200 mAh / g. Charge and discharge conditions were constant current (CC) / constant voltage (CV) from 3.0 V to 4.3 V with a 1 / 20C cutoff. Discharge capacity was measured using a 0.1C charge / 0.1C discharge cycle. The results are shown in Table 2 below.

[0139] (4) BET measurement

[0140] For the positive electrode active materials prepared in Examples and Comparative Examples, the specific surface areas were measured using a BET measurement device (Micromeritics TriStar II 3020).

[0141] (6) Measurement of Tap Density (T / D)

[0142] 10 g of each of the positive electrode active material powders of the examples and comparative examples were weighed, placed in a dedicated container, and tapped 3000 times. The volume was measured, and the tap density was calculated by dividing the weight by the volume. A JEL STAV II tap density meter (Jolting Volumeter) was used for the measurement.

[0143] (7) Average particle size (D50) measurement

[0144] The average particle size (D50) was measured using a particle size analyzer (PSA) manufactured by Microtrac.

[0145]

Table 2

[0146]

[0147] With reference to Table 2, it can be confirmed that the (200) plane full width at half maximum, grain size, BET specific surface area, tap density, and average particle size of the positive electrode active materials of Examples 1 to 3 all meet the recommended ranges. In addition, it can be confirmed that the discharge capacity of the positive electrode active materials prepared according to Examples 1 to 3 is higher than the discharge capacity of the positive electrode active materials prepared according to Comparative Examples 2 and 3, indicating that the positive electrode active materials of the Examples also have excellent electrochemical properties.

[0148] Experimental Example 3-Particle Analysis

[0149] Figure 1 The SEM analysis results of the positive electrode active material of Example 1 were measured at a magnification of 15,000 times. Figure 2 The SEM analysis results of the positive electrode active material of Comparative Example 2 were measured at a magnification of 15,000 times. Figure 3 The SEM analysis results of the positive electrode active material of Comparative Example 3 were measured at a magnification of 15,000 times.

[0150] refer to Figures 1 to 3 It can be confirmed that the positive electrode active material prepared in Example 1 has fine pores on the particle surface. However, it can be seen that the positive electrode active material prepared in Comparative Example 2 has almost no pores on the particle surface, while the positive electrode active material prepared in Comparative Example 3 has excessively large pores on the particle surface.

[0151] According to the above results, when the positive active material precursor for lithium secondary batteries according to one embodiment is used, it can be confirmed that the filling amount that can be filled into the sagger during the firing process is increased, thereby improving productivity and achieving a positive active material with excellent electrochemical characteristics.

[0152] The present invention is not limited to the embodiments described above, but can be implemented in various forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without changing the technical concept or basic features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims

1. A positive electrode active material precursor for a lithium secondary battery, wherein: The full width at half maximum (FWHM) (200) of the (200) plane diffraction peak obtained by X-ray diffraction can be in the range of 0.28° to 1.30°.

2. The positive electrode active material precursor for lithium secondary batteries according to claim 1, wherein: The grain size of the positive electrode active material precursor is in the range of 23 nm to 95 nm.

3. The positive electrode active material precursor for lithium secondary batteries according to claim 1, wherein: The specific surface area (BET) of the positive electrode active material precursor is 20 m 2 / g to 80m 2 / g range.

4. The positive electrode active material precursor for lithium secondary batteries according to claim 1, wherein: The tap density of the positive electrode active material precursor is 1.9 g / cc to 2.3 g / cc.

5. The positive electrode active material precursor for lithium secondary battery according to claim 1, wherein: The average particle size (D50) of the positive electrode active material precursor is 2 μm to 7 μm.

6. The positive electrode active material precursor for lithium secondary battery according to claim 1, wherein: The metal oxide is represented by the following chemical formula 1: [Chemical Formula 1] The a [Nor x Co y M1 z1 M2 z2 ]O2 In the chemical formula 1, M1 is Mn or Al, M2 is at least one of Al, Mg, Ti, Nb, W, Sc, Zr, Si, V, Fe, Y, Mo or a combination thereof, 0.8≤a≤1.2, 0.80≤x≤1, 0≤y≤0.2, 0≤z1≤0.2, 0≤z2≤0.2, and x+y+z1+z2=1.

7. The positive electrode active material precursor for lithium secondary battery according to claim 6, wherein: In the chemical formula 1, x satisfies the condition 0.87≤x<1.

8. A method for preparing a positive electrode active material for a lithium secondary battery, comprising: A step of preparing a metal hydroxide containing nickel, cobalt and manganese; a step of performing a first firing on the mixture of the metal hydroxide and the dopant to obtain a metal oxide precursor; a step of preparing a molded body using a mixture of the metal oxide precursor and the lithium raw material; After filling the molded body into a sagger, a step of preparing a fired body through a second firing process is performed; as well as The fired body is pulverized and classified.

9. The method for preparing a positive electrode active material for a lithium secondary battery according to claim 8, wherein: In the step of preparing the metal oxide precursor, The dopant is at least one of an oxide or hydroxide, a nitrate, and a combination thereof of at least one of Zr, Ti, W, Al, Mg, V, Co, and Ni.

10. The method for preparing a positive electrode active material for a lithium secondary battery according to claim 8, wherein: The first firing step is performed at a temperature ranging from 310° C. to 590° C. for 1 hour to 10 hours.

11. The method for preparing a positive electrode active material for a lithium secondary battery according to claim 8, wherein: The packing density of the prepared molded body is in the range of 1.0 g / cc to 2.5 g / cc.

12. The method for preparing a positive electrode active material for a lithium secondary battery according to claim 8, wherein: The step of preparing the molded body is performed using at least one of a disk pelletizer, an intensive mixer, a briquetting machine, a press, a spray dryer, and an extruder.

13. The method for preparing a positive electrode active material for a lithium secondary battery according to claim 8, wherein: The second firing step is performed at a temperature ranging from 850° C. to 950° C. for 10 hours to 30 hours.

14. A positive electrode for a lithium secondary battery, comprising: current collector; as well as A positive electrode active material layer is located on at least one side of the current collector and contains the positive electrode active material according to any one of claims 8 to 13.

15. A lithium secondary battery comprising: The positive electrode according to claim 14.

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