Precursor of positive electrode active material for lithium secondary battery, method for manufacturing positive electrode active material using the same, and lithium secondary battery including positive electrode active material manufactured using the same

Abstract

The present embodiment relates to a cathode active material precursor for a lithium secondary battery, a method for manufacturing a cathode active material using the same, and a lithium secondary battery including the cathode active material manufactured using the same. The cathode active material precursor for a lithium secondary battery according to one embodiment may have a full width at half maximum (FWHM(200)) of a diffraction peak of the (200) plane in X-ray diffraction in the range of 0.28° to 1.30°.

Description

[Technical Field]

[0001] The present embodiment relates to a cathode active material precursor for a lithium secondary battery, a method for manufacturing a cathode active material using the same, and a lithium secondary battery including the cathode active material manufactured using the same. [Background technology]

[0002] A lithium composite metal compound is used as a positive electrode active material for a lithium secondary battery, and such a positive electrode active material can be prepared by firing a powder-type raw material at a high temperature.

[0003] The firing process of the positive electrode active material involves heat treatment at a high temperature for a certain period of time in an air atmosphere containing oxygen at a certain concentration or more. In this process, the firing temperature and the maintenance time must be optimized to reduce the process cost.

[0004] When manufacturing the cathode active material, productivity can be improved by increasing the filling amount in the saggar, but if the filling amount is too high, the amount of unreacted lithium increases and the electrochemical properties may rapidly deteriorate due to the instability of the layered structure. Summary of the Invention [Problem to be solved by the invention]

[0005] The present embodiment aims to provide a cathode active material precursor for a lithium secondary battery that can minimize the manufacturing cost of the cathode active material while ensuring excellent electrochemical properties, a manufacturing method of the cathode active material using the same, and a lithium secondary battery including the cathode active material manufactured using the same. [Means for solving the problem]

[0006] In the positive electrode active material precursor for a lithium secondary battery according to one embodiment, the full width at half maximum (FWHM)(200) of the diffraction peak of the (200) plane measured by X-ray diffraction may be in the range of 0.28° to 1.30°.

[0007] According to one embodiment, a method for manufacturing a positive electrode active material for a lithium secondary battery may include the steps of: preparing a metal hydroxide containing nickel, cobalt, and manganese; first heat-treating a mixture of the metal hydroxide and an additive to manufacture a metal oxide precursor; manufacturing a compact using a mixture of the metal oxide precursor and a lithium source material; filling the compact into a sagger and then performing a second heat-treating process to manufacture a sintered compact; and crushing and classifying the sintered compact.

[0008] The positive electrode according to an embodiment may include a current collector; and a positive electrode active material layer located on at least one surface of the current collector and including the positive electrode active material manufactured using the method for manufacturing a positive electrode active material according to the embodiment.

[0009] A lithium secondary battery according to an embodiment may include the positive electrode. [Effects of the Invention]

[0010] According to the present embodiment, a positive electrode active material for a lithium secondary battery can be obtained by manufacturing a compact using a metal oxide precursor obtained by first heat-treating a hydroxide in an oxide form, and then carrying out a calcination process to manufacture the positive electrode active material, thereby achieving a positive electrode active material for a lithium secondary battery that can increase its mass while maintaining excellent electrochemical properties.

[0011] In addition, by increasing the amount of material filled in the saggar during firing, the manufacturing cost of the positive electrode active material can be minimized, resulting in a significant improvement in economic efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows the results of SEM analysis of the positive electrode active material precursor prepared in Example 1, measured at 15,000 magnifications. [Figure 2] 1 shows the results of SEM analysis of the positive electrode active material precursor produced in Comparative Example 2, measured at 15,000 magnifications. [Figure 3]1 shows the results of SEM analysis of the positive electrode active material precursor produced in Comparative Example 3, measured at 15,000 magnifications. DETAILED DESCRIPTION OF THE INVENTION

[0013] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited to these. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Therefore, a first part, component, region, layer, or section described below can be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0014] The terminology used herein is merely for the purpose of referring to particular embodiments and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. As used in this specification, the term "comprising" means to embody particular features, regions, integers, steps, operations, elements, and / or components, and does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0015] When a part is referred to as being "on" or "above" another part, it means that it is exactly on or above the other part, or there may be other parts between them. In contrast, when a part is referred to as being "directly on" another part, there are no other parts between them.

[0016] Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries are additionally interpreted as having a meaning consistent with the relevant technical literature and the presently disclosed content, and are not interpreted in an ideal or very formal sense unless defined.

[0017] Unless otherwise specified, % means % by weight, and 1 ppm is 0.0001% by weight.

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to exemplary embodiments thereof, so that those skilled in the art can easily understand and practice the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments set forth herein.

[0019] The embodiment will be specifically described below.

[0020] In one embodiment of the positive electrode active material precursor for a lithium secondary battery, the full width at half maximum (FWHM(200)) of the diffraction peak of the (200) plane by X-ray diffraction may be in the range of 0.28° to 1.30°, more specifically, 0.28° to 1.15°. The crystal grain size of the positive electrode active material precursor may be in the range of 23 nm to 95 nm, more specifically, 25 nm to 65 nm. When the full width at half maximum (FWHM) of the (200) plane and the crystal grain size satisfy the above ranges, the packing density can be increased during the manufacturing process, thereby improving the productivity of the positive electrode active material.

[0021] The specific surface area (BET) of the positive electrode active material precursor is 20 m 2 / g~80m 2 / g, more specifically, 20m 2 / g~60m 2 When the specific surface area is within this range, not many voids are formed in the cathode active material precursor, and when a cathode active material prepared using the same is applied to a battery, side reactions with the electrolyte are suppressed, resulting in excellent electrochemical properties.

[0022] The tap density of the positive electrode active material precursor may be in the range of 1.9 g / cc to 2.3 g / cc. When the tap density is in this range, a positive electrode active material having excellent electrochemical properties such as a long life and resistance characteristics can be realized.

[0023] The positive electrode active material precursor may have an average particle size (D50) of 2 μm to 7 μm, more specifically, 3 μm to 6 μm. When the average particle size is in this range, the lithium diffusion rate is fast and excellent electrochemical properties can be ensured.

[0024] The metal oxide may be represented by the following chemical formula 1:

[0025] [Chemical formula 1] Li a [Ni x Co y M1 z1 M2 z2 ]O2

[0026] In Formula 1, M1 may be Mn or Al, and M2 may be at least one of Al, Mg, Ti, Nb, W, Sc, Zr, Si, V, Fe, Y, Mo, or a combination thereof.

[0027] In Formula 1, lithium may be included in a content corresponding to a, i.e., 0.8≦a≦1.2. If a is too small, the capacity may decrease, while if a is too large, the strength of the sintered positive electrode active material may increase, making it difficult to pulverize, and the amount of gas generated may increase due to an increase in lithium by-products. Considering the effect of controlling the lithium content in improving the capacity characteristics of the positive electrode active material and the balance of sinterability during active material production, the lithium may more preferably be included in a content of 0.9≦a≦1.1.

[0028] In the above Chemical Formula 1, nickel can be contained in a content corresponding to x, that is, 0.80 ≤ x < 1. When x is sufficiently large, i.e., 0.8 or more, a sufficient amount of nickel contributing to charge and discharge can be ensured, and high capacity can be achieved. More specifically, it can be 0.87 ≤ x < 1. When the nickel content satisfies the above range, a positive electrode active material having high output characteristics can be realized. Also, when the nickel content is 0.87 mol or more, the positive electrode active material manufactured using this has a high energy density per unit volume, so the capacity of the battery to which this is applied can be improved, and it is very suitable for use in electric vehicles.

[0029] In the above Chemical Formula 1, cobalt can be contained in a content corresponding to y, that is, 0 < y ≤ 0.2. Cobalt can improve the capacity and lifespan of the battery. More specifically, the cobalt can be contained in a content of 0.01 ≤ y ≤ 0.1.

[0030] In the above Chemical Formula 1, manganese can be contained in a content corresponding to z1, that is, 0 < z1 ≤ 0.2. Manganese can improve the stability of the positive electrode active material and, as a result, improve the stability of the battery. More specifically, the manganese can be contained in a content of 0.01 ≤ y ≤ 0.1.

[0031] In the above Chemical Formula 1, M2 is a doping element. The doping element M2 can be contained in a content corresponding to z2, that is, 0 ≤ z2 ≤ 0.2. In the positive electrode active material, the selection of the doping element is important to ensure lifespan and various electrochemical performances. In this embodiment, by applying various doping elements as described above, the characteristics of the positive electrode active material can be improved. More specifically, the doping element can be contained in a content of 0.001 ≤ y ≤ 0.08.

[0032] According to one embodiment, a method for manufacturing a positive electrode active material for a lithium secondary battery may include the steps of: preparing a metal hydroxide containing nickel, cobalt, and manganese; first heat-treating a mixture of the metal hydroxide and an additive to manufacture a metal oxide precursor; manufacturing a compact using a mixture of the metal oxide precursor and a lithium source material; filling the compact into a sagger and then performing a second heat-treatment to manufacture a sintered compact; and crushing and classifying the sintered compact.

[0033] First, a metal hydroxide containing nickel, cobalt, and manganese is prepared.

[0034] The metal hydroxide can be produced by a conventional method known in the art, for example, a solid-state reaction method, a coprecipitation method, a sol-gel method, a hydrothermal synthesis method, or the like.

[0035] In the co-precipitation method, for example, a metal salt aqueous solution containing a nickel source material, a cobalt source material, a manganese source material, and water is prepared, and then the metal salt aqueous solution is supplied to a co-precipitation reactor to obtain a metal hydroxide.

[0036] Next, the mixture of the metal hydroxide and the additive is subjected to a primary heat treatment to prepare a metal oxide precursor.

[0037] The additive may be at least one selected from the group consisting of oxides or hydroxides, nitrates, and combinations thereof of at least one of Zr, Ti, W, Al, Mg, V, Co, and Ni.

[0038] The primary heat treatment can be carried out for 1 hour to 10 hours at a temperature in the range of 310° C. to 590° C. or 350° C. to 550° C. When the primary heat treatment is carried out under the above conditions, the packing density described below can be ensured.

[0039] The physical properties of the metal oxide precursor, i.e., characteristics such as half-width, crystal grain size, specific surface area, tap density, and average grain size, are the same as those described above, and therefore will not be described here.

[0040] Thereafter, a step of manufacturing a compact using a mixture of the metal oxide precursor and the lithium source material is performed.

[0041] The mixture may be prepared so that the molar ratio (Li / Me) of lithium (Li) to all metals (Me) excluding lithium is in the range of 1.0 to 1.1, or in the range of 1.01 to 1.08.

[0042] The compact may be produced using at least one of a disk pelletizer, an intensive mixer, a briquetting machine, a press, a spray dryer, and an extruder.

[0043] The packing density of the produced compact may be in the range of 1.0 g / cc to 2.5 g / cc. When the packing density is in this range, the packing amount in the sagger can be increased during the firing process, resulting in improved productivity of the positive electrode active material.

[0044] Next, the compact is filled into a sagger and subjected to a secondary heat treatment to produce a sintered body. The secondary heat treatment can be performed at a temperature between 850°C and 950°C for 10 to 30 hours. When the secondary heat treatment temperature and time conditions satisfy the above ranges, the generation of cation mixing can be reduced, thereby improving the structural stability of the layered structure positive electrode active material. The improved structural stability has the advantages of longer life, lower output, and lower resistance.

[0045] Next, the sintered body is crushed and classified to obtain the positive electrode active material for a lithium secondary battery according to the present embodiment.

[0046] In one embodiment, a positive electrode is provided, comprising: a current collector; and a positive electrode active material layer located on one surface of the current collector and including the positive electrode active material produced according to the production method of the above-described embodiment.

[0047] 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 will be omitted.

[0048] The current collector may be made of, for example, stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like.

[0049] Meanwhile, the positive electrode active material layer may include a binder and a conductive material.

[0050] The binder serves to improve adhesion between positive electrode active material particles and between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and various copolymers thereof. These may be used alone or in combination. The binder may be present in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0051] The conductive material is used to impart conductivity to the electrode. Any conductive material can be used without particular limitations as long as it does not cause chemical changes in the battery and has electronic conductivity. Specific examples include graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber, such as copper, nickel, aluminum, and silver; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives. These materials can be used alone or in combination. The conductive material can typically be present in an amount of 1 to 30 wt % based on the total weight of the positive electrode active material layer.

[0052] The positive electrode may be manufactured by a conventional method for manufacturing a positive electrode, except for using the positive electrode active material.

[0053] Specifically, the positive electrode can be manufactured by coating a positive electrode active material layer-forming composition containing the above-described positive electrode active material and, optionally, 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.

[0054] The solvent may be a solvent commonly used in the art, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and may be used alone or in combination. The amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, and to provide a viscosity that allows excellent thickness uniformity during subsequent application to produce a positive electrode, taking into consideration the coating thickness of the slurry and the production yield.

[0055] Alternatively, the positive electrode can be produced by casting the positive electrode active material layer-forming composition on a separate support, peeling the composition from the support, and laminating the resulting film on a positive electrode current collector.

[0056] In one embodiment, a lithium secondary battery is provided that includes the positive electrode.

[0057] The lithium secondary battery may include a positive electrode, a negative electrode facing the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, as described above. The lithium secondary battery may further include a battery container that houses the electrode assembly including the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0058] 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.

[0059] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. Examples of materials that can be used include copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloys. The negative electrode current collector typically has a thickness of 3 to 500 μm. As with the positive electrode current collector, the current collector surface may be provided with fine irregularities to enhance the binding strength of the negative electrode active material. The negative electrode current collector may be used in various forms, such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0060] The negative electrode active material layer may optionally contain a binder and a conductive material together with the negative electrode active material. For example, the negative electrode active material layer may be formed by coating a negative electrode active material layer-forming composition containing the negative electrode active material and, optionally, the binder and the conductive material on a negative electrode current collector and drying the coating, or by casting the negative electrode-forming composition on a separate support, peeling it off from the support, and laminating the resulting film on the negative electrode current collector.

[0061] The negative electrode active material may be a compound capable of reversible lithium intercalation and deintercalation. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, and Al alloys; metal oxides capable of doping and dedoping lithium, such as SiOβ(0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; and composites containing the metallic compounds and carbonaceous materials, such as Si-C composites and Sn-C composites. A mixture of one or more of these may also be used. Alternatively, a thin film of metallic lithium may also be used as the negative electrode active material. Carbon materials, such as low-crystalline carbon and high-crystalline carbon, may both be used. Typical low-crystalline carbons are soft carbon and hard carbon, while typical high-crystalline carbons are amorphous, plate-like, scaly, spherical, or fibrous natural or artificial graphite, kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature-fired carbons such as petroleum or coal tar pitch-derived cokes.

[0062] The binder and conductive material may be the same as those described above for the positive electrode.

[0063] Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Examples of such separators include polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more of these. Mixed multilayer films, such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator, may also be used.

[0064] In addition, in the lithium secondary battery, examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used when manufacturing a lithium secondary battery.

[0065] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0066] The organic solvent can be used without any particular limitation as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent can be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, ε-caprolactone, etc.; dibutyl ether; ether-based solvents such as ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; carbonate-based solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylenecarbonate (EC), and propylenecarbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; tolyls such as R-CN (where R is a C2-C20 linear, branched, or cyclic hydrocarbon group that may contain a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among these, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) with high ionic conductivity and a high dielectric constant, which can improve the charge / discharge performance of a battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred. In this case, the cyclic carbonate and the chain carbonate are mixed in a volume ratio of about 1:1 to about 1:9, which can improve the performance of the electrolyte solution.

[0067] The lithium salt can be any compound capable of providing lithium ions used in lithium secondary batteries. Specifically, examples of the lithium salt include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, and LiB(C2O4)2. The lithium salt concentration is preferably within the range of 0.1 to 2.0 M. When the lithium salt concentration falls within this range, the electrolyte has appropriate conductivity and viscosity, resulting in excellent electrolyte performance and efficient lithium ion migration.

[0068] As described above, the lithium secondary battery including the cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, and is therefore useful in the fields of portable devices such as mobile phones, laptops, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs). [Example]

[0069] The following examples of the present invention will be described in detail. However, these examples are presented as examples and are not intended to limit the present invention, which is defined only by the scope of the claims set forth below.

[0070] Example 1 (1) Preparation of metal oxide precursors The precursor was prepared by a common co-precipitation method.

[0071] Specifically, NiSO4·6H2O was used as the nickel source material, CoSO4·7H2O as the cobalt source material, and MnSO4·H2O as the manganese source material. These raw materials were dissolved in distilled water to produce metal salt aqueous solutions.

[0072] After preparing the coprecipitation reactor, N2 was purged to prevent oxidation of metal ions during the coprecipitation reaction, and the reactor temperature was maintained at 50°C.

[0073] NH4(OH) was added to the coprecipitation reactor as a chelating agent, and NaOH was used to adjust the pH. The precipitate obtained by the coprecipitation process was filtered, washed with distilled water, and dried in an oven at 100°C for 24 hours to produce metal hydroxide.

[0074] The composition of the produced metal hydroxide is (Ni 0.96 Co 0.03 Mn 0.01 )(OH)2.

[0075] The mixture of the metal hydroxide and ZrO2 as an additive was filled into a mullite saggar, which was then placed in an oxygen atmosphere furnace and subjected to a primary heat treatment at 500°C to prepare a metal oxide precursor.

[0076] (2) Manufacture of positive electrode active material The metal oxide precursor prepared in step 1, the lithium source material LiOH, and water were mixed and fed into a disk pelletizer to produce spherical compacts with an average diameter of 3 mm. The molar ratio of lithium (Li) to total metal (Me) (Li / Me) was 1.05.

[0077] The compact was filled into a mullite saggar, which was then placed in a sintering furnace under an oxygen atmosphere and subjected to a secondary heat treatment at 900°C. The material sintered by the secondary heat treatment was crushed and classified to prepare a cathode active material for a lithium secondary battery.

[0078] Example 2 (1) Preparation of metal oxide precursors A metal oxide precursor was prepared in the same manner as in Example 1, except that the primary heat treatment temperature was changed to 350°C.

[0079] (2) Manufacture of positive electrode active material A positive electrode active material for a lithium secondary battery was produced in the same manner as in Example 1.

[0080] Example 3 (1) Preparation of metal oxide precursors A metal oxide precursor was prepared in the same manner as in Example 1, except that the primary heat treatment temperature was changed to 550°C.

[0081] (2) Manufacture of positive electrode active material A positive electrode active material for a lithium secondary battery was produced in the same manner as in Example 1.

[0082] Comparative Example 1 (1) Preparation of metal hydroxide precursors A positive electrode active material precursor made of a metal hydroxide was produced in the same manner as in Example 1.

[0083] (2) Manufacture of positive electrode active material The precursor prepared in step 1, ZrO2 as an additive, LiOH as a lithium source material, and water were mixed and filled into a saggar, which was then placed in a sintering furnace under an oxygen atmosphere and fired at 900°C. The sintered material was crushed and classified to produce a positive electrode active material for lithium secondary batteries.

[0084] Comparative Example 2 (1) Preparation of metal oxide precursors A metal oxide precursor was prepared in the same manner as in Example 1, except that the primary heat treatment temperature was changed to 300°C.

[0085] (2) Manufacture of positive electrode active material A positive electrode active material for a lithium secondary battery was produced in the same manner as in Example 1.

[0086] Comparative Example 3 (1) Preparation of metal oxide precursors A metal oxide precursor was prepared in the same manner as in Example 1, except that the primary heat treatment temperature was changed to 600°C.

[0087] (2) Manufacture of positive electrode active material A positive electrode active material for a lithium secondary battery was produced in the same manner as in Example 1.

[0088] Experimental Example 1 - Packing density measurement The packing density was measured for the compact prepared using a disc pelletizer to prepare the positive electrode active material in Example 1 and the mixture of precursor, additive, and lithium source material in Comparative Example 1. The results are shown in Table 1 below.

[0089] [Table 1]

[0090] Referring to Table 1, it can be seen that the packing density of the compact prepared according to Example 1 was increased by 1.5 times or more compared to the mixture prepared according to Comparative Example 1. Therefore, when the positive electrode active material of Example 1 is used, the charging amount per firing can be increased, resulting in improved firing productivity.

[0091] Experimental Example 2: Electrochemical property measurement (1) Coin cell half cell manufacturing CR2032 coin cells were fabricated using the positive electrode active materials prepared in the Examples and Comparative Examples, and electrochemical evaluation was performed.

[0092] Specifically, the positive electrode active material, conductive material (Super-P), and polyvinylidene fluoride (PVdF) binder were mixed in a weight ratio of 92:2, and this mixture was added to N-methyl-2-pyrrolidone solvent so that the solid content was approximately 30 wt% to prepare a positive electrode active material slurry.

[0093] The slurry was coated on an aluminum foil (thickness: 15 μm) as a positive electrode current collector using a doctor blade, dried in vacuum at 120° C. for 5 hours, and then rolled to prepare a positive electrode.

[0094] A 2032 coin-type half cell was fabricated using the cathode, lithium metal anode (300 μm thick, MTI), electrolyte, and polypropylene separator in a conventional manner. The electrolyte was a mixed solution prepared by dissolving 1MLiPF6 in a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate (EMC) (mixing ratio EC:DMC:EMC = 3:4:3 vol%). The fabricated coin cell was aged at room temperature for 12 hours, and then its electrochemical properties were measured.

[0095] (2) XRD measurement (FWHM and grain size measurement) The positive electrode active materials prepared in the examples and comparative examples were subjected to X-ray diffraction analysis using X'pert pro (PANalytical) with Cu Kα radiation (1.54056 Å). The results are shown in Table 2 below.

[0096] The full width at half maximum (FWHM) 200 indicates the half width of the peak corresponding to the (200) plane (peak with 2θ of approximately 43-44°).

[0097] The grain size was also measured using the same equipment.

[0098] (3) Discharge capacity evaluation The capacity evaluation was performed with 200mAh / g as the reference capacity, and the charge / discharge conditions were constant current (CC) / constant voltage (CV) 3.0V-4.3V with a 1 / 20C cut-off. The discharge capacity was measured by charging at 0.1C and discharging at 0.1C. The results are shown in Table 2 below.

[0099] (4) BET measurement The specific surface area of ​​the positive electrode active materials prepared in the examples and comparative examples was measured using a BET measurement device (Micromeritics TriStar II3020).

[0100] (6) Tap density (T / D) measurement 10 g of the positive electrode active material powders of the Examples and Comparative Examples were weighed and placed in a dedicated container, and the container was tapped 3,000 times to measure the volume. The tap density was calculated by dividing the weight by the volume. A JEL STAV II Jolting Volumeter was used as the measuring device.

[0101] (7) Average particle diameter (D50) measurement The average particle size (D50) was measured using a particle size analyzer (PSA) from Microtrac.

[0102] [Table 2]

[0103] Referring to Table 2, it can be seen that the (200) plane half-width, grain size, BET, tap density, and average grain size of the positive electrode active materials of Examples 1 to 3 satisfy the proposed ranges. In addition, it can be seen that the discharge capacities of the positive electrode active materials prepared in Examples 1 to 3 are greater than those of the positive electrode active materials prepared in Comparative Examples 2 and 3, indicating that the positive electrode active materials of the Examples also have excellent electrochemical properties.

[0104] Experimental Example 3 - Particle Analysis Fig. 1 shows the SEM analysis results of the positive electrode active material prepared in Example 1 at a magnification of 15,000 times, Fig. 2 shows the SEM analysis results of the positive electrode active material prepared in Comparative Example 2 at a magnification of 15,000 times, and Fig. 3 shows the SEM analysis results of the positive electrode active material prepared in Comparative Example 3 at a magnification of 15,000 times.

[0105] 1 to 3, it can be seen that fine pores are present on the surfaces of the silver particles of the positive electrode active material prepared in Example 1. However, the positive electrode active material prepared in Comparative Example 2 has almost no pores on the particle surfaces, while the positive electrode active material prepared in Comparative Example 3 has very large pores on the surfaces of the silver particles.

[0106] From these results, it can be seen that when the positive electrode active material precursor for a lithium secondary battery according to an embodiment is used, the amount of material that can be filled into a sagger in the firing process increases, improving productivity, and at the same time, a positive electrode active material with excellent electrochemical properties can be realized.

[0107] The present invention is not limited to the above-described embodiments, and can be manufactured in various different forms, and a person skilled in the art to which the present invention pertains can understand that the present invention can be embodied in other specific forms without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting.

Claims

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

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

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

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

6. The metal oxide is a positive electrode active material precursor for a lithium secondary battery according to claim 1, represented by the following chemical formula 1: [Chemical formula 1] Li ａ [Ni ｘ Co ｙ M1 ｚ１ M2 ｚ２ ]O ２ In the above 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. 7. The positive electrode active material precursor for a lithium secondary battery according to claim 6, wherein x in Formula 1 satisfies 0.87≦x<1.

8. providing a metal hydroxide containing nickel, cobalt, and manganese; a step of subjecting the mixture of the metal hydroxide and the additive to a primary heat treatment to prepare a metal oxide precursor; preparing a compact using the mixture of the metal oxide precursor and the lithium source material; Packing the compact into a sagger and then subjecting it to a secondary heat treatment to produce a sintered body; and crushing and classifying the sintered body; The method for producing a positive electrode active material for a lithium secondary battery includes the steps of:

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

10. The method for producing a positive electrode active material for a lithium secondary battery according to claim 8, wherein the primary heat treatment is performed at a temperature in the range of 310°C to 590°C for 1 hour to 10 hours.

11. In the step of producing the molded body, 9. The method for producing a positive electrode active material for a lithium secondary battery according to claim 8, wherein the packing density of the produced compact is in the range of 1.0 g / cc to 2.5 g / cc.

12. 10. The method of claim 8, wherein the step of preparing the compact 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. In the step of producing the sintered body, The method for manufacturing a positive electrode active material for a lithium secondary battery according to claim 8, wherein the second heat treatment is performed at a temperature in the range of 850°C to 950°C for 10 hours to 30 hours.

14. a current collector; and a positive electrode active material layer located on at least one surface of the current collector, the positive electrode active material layer comprising the positive electrode active material produced by the method according to any one of claims 8 to 13; A positive electrode for a lithium secondary battery comprising:

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

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