Method for preparing cathode active material

Abstract

The present disclosure relates to a method for preparing a cathode active material, comprising: obtaining a transition metal hydroxide containing nickel, cobalt and manganese; heating a first mixture in an oxygen atmosphere at a first temperature so as to obtain a preliminary lithium transition metal oxide; and heating a second mixture in an oxygen atmosphere at a second temperature so as to obtain a lithium transition metal oxide, wherein the first mixture comprises the transition metal hydroxide and a lithium compound, the second mixture comprises the preliminary lithium transition metal oxide, the first temperature is 700-1,000 °C, and the preliminary lithium transition metal oxide is obtained by heating the first mixture at a heating rate of 0.1-1.8 °C / min in a temperature range of 500-600 °C.

Description

Method for manufacturing positive electrode active material

[0001] The present disclosure relates to a method for manufacturing an anode active material.

[0002] Lithium-ion batteries can repeatedly charge and discharge through the intercalation and deintercalation of lithium ions. Lithium-ion batteries supply power to external devices through these repeated charging and discharging cycles.

[0003] Lithium composite oxides can be used for the intercalation / deintercalation of lithium ions. Lithium composite oxides form a structure in which lithium ions and transition metals are combined, storing lithium ions internally and releasing them externally. The transition metals in lithium composite oxides may include nickel, cobalt, and manganese.

[0004] The characteristics of lithium composite oxides can have a significant impact on the lifespan characteristics and performance of lithium secondary batteries.

[0005] The present disclosure aims to provide a method for manufacturing a positive electrode active material having excellent performance.

[0006] The present disclosure aims to provide a method for manufacturing a positive electrode active material capable of improving the lifespan characteristics and battery characteristics of a battery.

[0007] The present disclosure aims to provide a method for manufacturing a positive electrode active material capable of reducing residual lithium located on the surface of the positive electrode active material.

[0008] A method for manufacturing an anode active material according to the present disclosure comprises: obtaining a transition metal hydroxide comprising nickel, cobalt, and manganese; heating a first mixture in an oxygen atmosphere and at a first temperature to obtain a preliminary lithium transition metal oxide; and heating a second mixture in an oxygen atmosphere and at a second temperature to obtain a lithium transition metal oxide; wherein the first mixture comprises the transition metal hydroxide and the lithium compound, and the second mixture comprises the preliminary lithium transition metal oxide, and the first temperature is within the range of 700 ℃ to 1000 ℃, and to obtain the preliminary lithium transition metal oxide, the first mixture is heated at a heating rate within the range of 0.1 ℃ / min to 1.8 ℃ / min at a temperature within the range of 500 ℃ to 600 ℃.

[0009] The method for obtaining the above-mentioned preliminary lithium transition metal oxide involves raising the temperature of the first mixture from a reference temperature to the first temperature; and maintaining the first mixture at the first temperature; the reference temperature may be in the range of 10°C to 30°C.

[0010] In obtaining the above preliminary lithium transition metal oxide, the first mixture may be maintained at the first temperature for 180 to 300 minutes.

[0011] The first temperature is within the range of 750 ℃ ​​to 800 ℃, and to obtain the preliminary lithium transition metal oxide, the first mixture is heated at a heating rate within the range of 1 ℃ / min to 1.6 ℃ / min at a temperature of 500 ℃ to 600 ℃, and to obtain the preliminary lithium transition metal oxide, the first mixture can be maintained at the first temperature for 180 minutes to 200 minutes.

[0012] The nickel content of the above transition metal hydroxide may be 60 mol% or more.

[0013] The first mixture further comprises a doping element precursor, and the doping element may include two or more selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

[0014] The above doping elements may include Ba and Zr.

[0015] The barium precursor content of the first mixture may be in the range of 0.1 mol% to 0.5 mol% based on metal elements excluding lithium among the transition metal hydroxides.

[0016] The zirconium precursor content of the first mixture may be in the range of 0.1 mol% to 0.5 mol% based on metal elements excluding lithium among the transition metal hydroxides.

[0017] The second mixture further comprises a doping element precursor, and the doping element may include two or more selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

[0018] The above second mixture may further include a cobalt precursor.

[0019] The cobalt precursor content of the second mixture may be in the range of 3 mol% to 4 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

[0020] At least one of the doping element precursors of the second mixture may be the same as the doping element precursor of the first mixture.

[0021] The second temperature mentioned above may be in the range of 650 ℃ to 750 ℃.

[0022] In obtaining the above-mentioned preliminary lithium transition metal oxide, the ratio of the time for maintaining the first mixture at the first temperature to the time for raising the temperature of the first mixture may be 0.5 or less.

[0023] The present disclosure can provide a method for manufacturing a positive electrode active material having excellent performance.

[0024] The present disclosure can provide a method for manufacturing a positive electrode active material that can improve the lifespan characteristics and battery characteristics of a battery.

[0025] The present disclosure can provide a method for manufacturing a positive electrode active material that can reduce residual lithium located on the surface of the positive electrode active material.

[0026] Figures 1 to 3 show the CP-SEM cross-sectional imaging results of Example 1.

[0027] Figures 4 to 6 show the CP-SEM cross-sectional imaging results of Comparative Example 1.

[0028] Figures 7 to 9 show the CP-SEM cross-sectional imaging results of Comparative Example 2.

[0029] Figures 10 to 12 show the CP-SEM cross-sectional imaging results of Comparative Example 3.

[0030] Figure 13 shows the XRD analysis results of Example 1 and Comparative Examples 1 to 3.

[0031] The present disclosure is described in detail below.

[0032] One embodiment of the present disclosure relates to a method for manufacturing a positive electrode active material.

[0033] A method for manufacturing a positive electrode active material according to the present disclosure comprises: obtaining a transition metal hydroxide comprising nickel, cobalt, and manganese; heating a first mixture in an oxygen atmosphere at a first temperature to obtain a preliminary lithium transition metal oxide; and heating a second mixture in an oxygen atmosphere at a second temperature to obtain a lithium transition metal oxide. The first mixture comprises the transition metal hydroxide and the lithium compound. The second mixture comprises the preliminary lithium transition metal oxide. The first temperature is within the range of 700 °C to 1000 °C. To obtain the preliminary lithium transition metal oxide, the first mixture is heated at a heating rate within the range of 0.1 °C / min to 1.8 °C / min at a temperature of 500 °C to 600 °C.

[0034] The present disclosure may perform obtaining a transition metal hydroxide comprising nickel, cobalt, and manganese. The transition metal hydroxide may be used as a precursor for the lithium transition metal oxide described below. A preliminary lithium transition metal oxide may be obtained by heating the transition metal hydroxide and a lithium compound together. The lithium compound is used as a lithium raw material. The lithium transition metal oxide may be obtained by heating the preliminary lithium transition metal oxide together with a boron precursor.

[0035] The above transition metal hydroxide can be obtained by using a precursor comprising at least one of the above transition metals. Specifically, the above transition metal hydroxide can be prepared by applying a coprecipitation method using a precursor comprising at least one of the above transition metals. Methods for preparing transition metal hydroxides by coprecipitation are known, and these may be applied without limitation in the present disclosure.

[0036] Obtaining the above transition metal hydroxide may mean obtaining a commercially available transition metal hydroxide.

[0037] The present disclosure may perform obtaining a preliminary lithium transition metal oxide by heating a first mixture in an oxygen atmosphere and at a first temperature. The first mixture comprises the transition metal hydroxide and the lithium compound.

[0038] The lithium compound may be a lithium raw material that reacts with the transition metal hydroxide to form a lithium transition metal oxide. The lithium compound may include one or more selected from the group consisting of lithium hydroxide, lithium carbonate, lithium nitrate, or lithium acetate. It may be preferable that the lithium compound be mixed such that the ratio of the number of lithium atoms (Li) to the total number of metal atoms other than lithium (Metal) in the first mixture (Li / Metal) satisfies a range of 0.95 to 1.10.

[0039] Lithium anhydrous hydroxide (LiOH·H2O) may be provided as a lithium raw material for reacting with the transition metal hydroxide. The lithium anhydrous hydroxide (LiOH·H2O) may be converted into lithium hydroxide (LiOH) through a dehydration reaction. The dehydration reaction may be carried out at a relatively low temperature (e.g., 100°C or lower).

[0040] The lithium hydroxide (LiOH) may react with the transition metal hydroxide. The lithium hydroxide may react with the transition metal hydroxide at a relatively high temperature (e.g., about 500°C to 600°C). Not all of the lithium hydroxide (LiOH) may react with the transition metal hydroxide, but only a portion of the lithium hydroxide (LiOH) may react. As a result, the lithium hydroxide (LiOH) that did not react with the transition metal hydroxide may exist on the surface of the transition metal hydroxide. Here, the lithium compound existing on the surface of the transition metal hydroxide may be defined as residual lithium. The residual lithium may exist in the form of lithium oxide (Li2O).

[0041] The first mixture may further include a doping element precursor. The doping element may include two or more selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

[0042] The above doping element can react with the above transition metal hydroxide to dope the above preliminary lithium transition metal oxide.

[0043] The above doping elements may include Ba and Zr. The first mixture may include a barium precursor. The first mixture may include a zirconium precursor. The first mixture may include two or more selected from the group consisting of Ba(OH)2, BaF, BaO, Ba(C5H7O2)2, BACO3, Ba(NO3)2, BaCl2, ZrH2, and Zr(OH)2. The first mixture may also be provided as a single mixture each comprising one or more selected from the group consisting of Ba(OH)2, BaF, BaO, Ba(C5H7O2)2, BACO3, Ba(NO3)2, and BaCl2, and one or more selected from the group consisting of ZrH2 and Zr(OH)2.

[0044] The barium precursor content of the first mixture may be in the range of 0.1 mol% to 0.5 mol% based on the metal element excluding lithium among the transition metal hydroxide. The barium precursor content of the first mixture may be 0.15 mol% or more, 0.2 mol% or more, 0.25 mol% or more, 0.3 mol% or more, 0.35 mol% or more, or 0.4 mol% or more based on the metal element excluding lithium among the transition metal hydroxide. The barium precursor content of the first mixture may be 0.45 mol% or less, 0.4 mol% or less, 0.35 mol% or less, 0.3 mol% or less, 0.25 mol% or less, 0.2 mol% or less, or 0.15 mol% or less based on the metal element excluding lithium among the transition metal hydroxide.

[0045] The zirconium precursor content of the first mixture may be in the range of 0.1 mol% to 0.5 mol% based on the metal element excluding lithium among the transition metal hydroxide. The zirconium precursor content of the first mixture may be 0.15 mol% or more, 0.2 mol% or more, 0.25 mol% or more, 0.3 mol% or more, 0.35 mol% or more, or 0.4 mol% or more based on the metal element excluding lithium among the transition metal hydroxide. The zirconium precursor content of the first mixture may be 0.45 mol% or less, 0.4 mol% or less, 0.35 mol% or less, 0.3 mol% or less, 0.25 mol% or less, 0.2 mol% or less, or 0.15 mol% or less based on the metal element excluding lithium among the transition metal hydroxide.

[0046] The sum of the content of the barium precursor and the content of the zirconium precursor in the first mixture may be 0.3 mol% to 0.5 mol% or 0.35 mol% to 0.45 mol% based on the metal element excluding lithium among the transition metal hydroxides.

[0047] By satisfying the above range for the content of the barium precursor and the zirconium precursor of the first mixture, barium and zirconium can react smoothly with the transition metal hydroxide. As a result, barium and zirconium can be smoothly doped into the preliminary lithium transition metal oxide.

[0048] The above-mentioned preliminary lithium transition metal oxide may be obtained in a calcination furnace. The above-mentioned preliminary lithium transition metal oxide may be obtained in an oxygen atmosphere. The above-mentioned preliminary lithium transition metal oxide may be obtained by heating the first mixture at a first temperature. The first temperature may be in the range of 700 ℃ to 1000 ℃. More specifically, the first temperature may be 730 ℃, 740 ℃, 750 ℃, 760 ℃ or higher, 770 ℃ or higher, or 780 ℃ or higher. Additionally, the first temperature may be 900 ℃ or lower, 850 ℃ or lower, or 800 ℃ or lower.

[0049] Obtaining the above-mentioned preliminary lithium transition metal oxide may include raising the temperature of the first mixture from a reference temperature to the first temperature; and maintaining the first mixture at the first temperature. The reference temperature may be in the range of 10°C to 30°C. Meanwhile, raising the temperature of the first mixture from the reference temperature to the first temperature may mean that the temperature of the kiln containing the first mixture is raised from the reference temperature to the first temperature. Additionally, maintaining the first mixture at the first temperature may mean maintaining the first mixture inside the kiln while the temperature of the kiln is maintained at the first temperature.

[0050] The temperature of the kiln can be increased at a preset rate from the reference temperature until it reaches the first temperature. For example, the kiln can be heated from room temperature (25°C) until it reaches the first temperature. When the temperature of the kiln reaches the first temperature, the temperature of the kiln can be maintained at the first temperature for a preset time.

[0051] Meanwhile, in the process of reaching the first temperature, the first mixture may be heated at a heating rate within the range of 0.1 ℃ / min to 1.8 ℃ / min at a temperature of 500 ℃ to 600 ℃. More specifically, the first mixture may be heated at a heating rate of 0.2 ℃ / min or more, 0.3 ℃ / min or more, 0.4 ℃ / min or more, 0.5 ℃ / min or more, 0.6 ℃ / min or more, 0.7 ℃ / min or more, 0.8 ℃ / min or more, 0.9 ℃ / min or more, 1.0 ℃ / min or more, 1.1 ℃ / min or more, 1.2 ℃ / min or more, 1.3 ℃ / min or more, or 1.4 ℃ / min or more. In addition, the first mixture may be heated at a heating rate of 1.7 ℃ / min or less, 1.6 ℃ / min or less, or 1.5 ℃ / min or less.

[0052] The above transition metal hydroxide and the above lithium compound can be heated at a preset rate within the above temperature range to react smoothly.

[0053] At a temperature of 500°C or lower, the lithium compound does not react with the transition metal hydroxide, or even if it does react, only a small amount of the lithium compound may participate in the reaction. When the temperature is increased at a heating rate within the range of 0.1°C / min to 1.8°C / min at a temperature of 500°C to 600°C, the lithium compound and the transition metal hydroxide can react for a sufficient amount of time. That is, most of the lithium compound can react with the transition metal hydroxide. As a result, residual lithium and other impurities can be reduced, and the lifespan and capacity characteristics of the battery containing the positive electrode active material can be improved.

[0054] At temperatures exceeding 600°C, the lithium compound has passed the temperature range in which it can react, so even if the heating rate is controlled, the lithium compound and the transition metal hydroxide may not react sufficiently.

[0055] Meanwhile, if the heating rate is less than 0.1 ℃ / min, it may take a long time to heat the first mixture in the range of 500℃ to 600℃. Consequently, the efficiency of the manufacturing process may decrease and production costs may increase. If the heating rate exceeds 1.8 ℃ / min, sufficient time may not be provided for the lithium compound and the transition metal hydroxide to react. Consequently, the amount of residual lithium may be large, and the performance characteristics of the battery may be degraded.

[0056] In obtaining the above-mentioned preliminary lithium transition metal oxide, the first mixture may be maintained at the first temperature for 180 to 300 minutes. The first mixture may be maintained at the first temperature for a time of 250 minutes or less or 200 minutes or less.

[0057] The first mixture is maintained at the first temperature for a certain period of time so that heat can be transferred to the interior of the first mixture and excessive calcination can be prevented.

[0058] The sum of the time during which the temperature of the kiln is raised and the time during which the first temperature is maintained may be approximately 12 to 13 hours. The ratio of the time during which the first mixture is maintained at the first temperature relative to the time during which the first mixture is raised may be 0.5 or less. By controlling the time during which the first mixture is heated and maintained, the transition metal hydroxide can sufficiently react with the lithium compound, and the amount of residual lithium can be reduced.

[0059] The time for maintaining the first mixture at the first temperature may be 4 hours or less. The time for raising the temperature of the kiln may be 8 hours or more.

[0060] In obtaining the above-mentioned preliminary lithium transition metal oxide, the ratio of the time for raising the first mixture to the time for maintaining the first mixture at the first temperature may be 0.5 or less. By maintaining the time for raising the first mixture to the first temperature and the time for maintaining the first mixture at the first temperature at a preset ratio, the reaction between the transition metal hydroxide and the lithium compound can proceed appropriately.

[0061] After mixing the transition metal hydroxide and the first mixture and heating, a furnace cooling step may be performed. The furnace cooling step may be performed by removing the heat source of the kiln and leaving the calcined material in the kiln.

[0062] The above-mentioned lithium transition metal oxide may be obtained in a calcination furnace. The above-mentioned lithium transition metal oxide may be obtained under an oxygen atmosphere. The above-mentioned lithium transition metal oxide may be obtained by heating the second mixture at a second temperature. The second mixture may include the above-mentioned preliminary lithium transition metal oxide.

[0063] The second mixture may further include a doping element precursor. The doping element may include one or more selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

[0064] The above doping element can react with the above-mentioned pre-lithium transition metal oxide. As a result, the above-mentioned doping element can be doped into the lithium transition metal oxide.

[0065] The above doping element precursor may include a cobalt precursor. The above cobalt precursor may use one or more selected from the group consisting of CoCl2, Co(NO3)2, CoC2O4, and Co(OH)2.

[0066] The above cobalt precursor may be included in the second mixture, with the cobalt content set to be 2.5 mol% to 3.5 mol% based on the transition metal excluding lithium in the above preliminary lithium transition metal oxide.

[0067] The second temperature may be 650 ℃ to 750 ℃. The second temperature may be 660 ℃ or higher, 670 ℃ or higher, 680 ℃ or higher, or 690 ℃ or higher. Additionally, the second temperature may be 740 ℃ or lower, 730 ℃ or lower, 720 ℃ or lower, or 710 ℃ or lower.

[0068] The temperature of the kiln can be increased at a preset rate until it reaches the second temperature. When the temperature of the kiln reaches the second temperature, the temperature of the kiln can be maintained at the second temperature for a preset time. The sum of the time during which the temperature of the kiln is increased and the time during which it is maintained at the second temperature may be approximately 10 to 12 hours. Through this, the firing process can proceed properly.

[0069] In obtaining the above lithium transition metal oxide, the heating time until the temperature of the kiln reaches a second temperature may be shorter than the time during which the temperature of the kiln is maintained at the second temperature.

[0070] After the temperature of the above-mentioned kiln is maintained at a second temperature, a furnace cooling step may be performed, and the above-mentioned positive active material may be manufactured.

[0071]

[0072] Preparation Example 1. Preparation of transition metal hydroxide

[0073] Example 1. Anode active material

[0074] Spherical Ni by the co-precipitation method 0.98 Co 0.01 Ni 0.01 (OH)2 transition metal hydroxides are prepared. Specifically, 25 wt% NaOH and 30 wt% NH4OH are added to a 1.5 M complex transition metal sulfuric acid aqueous solution, in which nickel sulfate, cobalt sulfate, and manganese sulfate are mixed in a molar ratio of 98:1:1 (nickel sulfate:cobalt sulfate:manganese sulfate), in a 90 L reactor. The pH inside the reactor is maintained at 11.5, and the reactor temperature is maintained at 60 °C. At this time, N2, an inert gas, is introduced into the reactor to prevent oxidation of the prepared precursor. Once the synthesis stirring is complete, washing and dehydration are carried out using a filter press (F / P) device. As a result, Ni 0.98 Co 0.01 Ni 0.01 (OH)2 transition metal hydroxide is obtained.

[0075] Next, the transition metal hydroxide, the lithium raw material, the barium precursor, and the zirconium precursor are mixed. Here, LiOH (Li / (Metal) mol ratio = 1.05) is used as the lithium raw material. Ba(OH) is used as the barium precursor. ZrO2 is used as the zirconium precursor. The content of the barium precursor and the zirconium precursor are set so that the total content of barium and zirconium, based on the metal elements excluding lithium in the transition metal hydroxide, is 0.5 mol%. Subsequently, the temperature is raised from 25°C to 780°C over 8 hours and 48 minutes while maintaining an oxygen atmosphere in the calcination furnace. The heat treatment is performed such that the total time for raising the temperature in the calcination furnace and maintaining the temperature at 780°C is 12 hours. Afterward, the heat-treated compound is cooled in the furnace. As a result, a preliminary lithium transition metal oxide is obtained.

[0076] The above-mentioned preliminary lithium transition metal oxide is mixed with a cobalt precursor, an aluminum precursor, and a zirconium precursor. Co(OH)2 is used as the cobalt precursor. Al(OH)3 is used as the aluminum precursor. ZrO2 is used as the zirconium precursor. Subsequently, the calcination furnace is heated to 700°C over 2 hours and 35 minutes while maintaining an oxygen (O2) atmosphere, and the mixture is heat-treated for 8 hours and then cooled to obtain a lithium transition metal oxide.

[0077] Comparative Example 1. Anode active material

[0078] The same process as in Example 1 is repeated, except that the temperature is raised from 25°C to 780°C over 2 hours and 48 minutes while maintaining an oxygen (O2) atmosphere in the kiln to obtain the above-mentioned preliminary lithium transition metal oxide.

[0079] Comparative Example 2. Anode active material

[0080] The same process as in Example 1 is repeated, except that the temperature is raised from 25°C to 780°C over 4 hours and 48 minutes while maintaining an oxygen (O2) atmosphere in the kiln to obtain the above-mentioned preliminary lithium transition metal oxide.

[0081] Comparative Example 3. Anode active material

[0082] The same process as in Example 1 is repeated, except that the temperature is raised from 25°C to 780°C over 6 hours and 48 minutes while maintaining an oxygen (O2) atmosphere in the kiln to obtain the above-mentioned preliminary lithium transition metal oxide.

[0083]

[0084] Experimental Example 1. ICP Analysis Method

[0085] 0.1 g of lithium transition metal oxide prepared in the examples and comparative examples is mixed and dissolved in 20 g of deionized water and 10 g of dilute aqua regia, respectively. The mixture is then heated for 15 minutes. Deionized water is added so that the total weight of the mixture is 100 g, and each specimen of the examples and preparation examples is prepared. The concentrations of the transition metal and doping elements of each specimen of the examples and preparation examples are measured using an ICP analyzer (PerkinElmer OPTIMA, AVIO-550).

[0086]

[0087] Experimental Example 2. CP-SEM cross-sectional imaging of lithium transition metal oxide

[0088] CP-SEM cross-sections were taken of the lithium transition metal oxides prepared in each example and preparation example. A scanning electron microscope from HITACHI was used as the measurement equipment, and cross-sections were measured at a magnification of 7,000x under a voltage condition of 2 kV.

[0089] FIGS. 1 to 3 illustrate the CP-SEM cross-sectional imaging results of Example 1. FIGS. 4 to 6 illustrate the CP-SEM cross-sectional imaging results of Example 1. FIGS. 7 to 9 illustrate the CP-SEM cross-sectional imaging results of Example 1. FIGS. 10 to 12 illustrate the CP-SEM cross-sectional imaging results of Example 1.

[0090] Referring to FIGS. 1 to 12, it can be seen that the size of the lithium compound decreases as the time of heating the first mixture within the range of 500 °C to 600 °C increases. It is presumed that the amount of the lithium compound decreases as the lithium compound reacts with the transition metal hydroxide.

[0091]

[0092] Experimental Example 3. XRD Analysis of Lithium Transition Metal Oxides

[0093] XRD analysis was performed on the lithium transition metal oxides prepared in each example and preparation example. Bruker's D8 ADVANCE was used as the analysis instrument. Cu-Kα (1.5406 Å) was used as the X-ray source, and the θ-2θ scan (Bragg-Brentano parafocusing geometry) method was used, with the scan interval set to 10 to 120 degrees (2θ) and the scan speed set to 0.01 degrees / min.

[0094] In addition, quantitative analysis of lithium transition metal oxides was performed using the Rietveld refinement method. The space group was set to Fm-3m.

[0095] FIG. 13 shows the XRD analysis results of Example 1 and Comparative Examples 1 to 13.

[0096] Referring to FIG. 13 and Table 1 below, it can be seen that the longer the heating time of the first mixture within the range of 500°C to 600°C, the lower the ratio of the lithium compound to the transition metal in the lithium transition metal oxide. This suggests that the lithium compound is reduced as it reacts with the transition metal hydroxide.

[0097]

[0098] Experimental Example 4. Evaluation of Electrochemical Characteristics of a Lithium Secondary Battery

[0099] A positive electrode slurry is prepared by dispersing 95.7 wt% of the positive electrode active material prepared in the above preparation example, 2 wt% of artificial graphite, and 2.3 wt% of PVDF binder in 30 g of N-methyl-2-pyrrolidone (NMP). The positive electrode slurry is uniformly coated onto an aluminum thin film with a thickness of 15 μm and vacuum dried at 135 ℃ to produce a positive electrode for a lithium secondary battery. A coin battery is prepared by using a lithium foil as a counter electrode for the positive electrode, a porous polyethylene film (Celgard 2300, thickness: 25 μm) as a separator, and an electrolyte in which LiPF6 is present at a concentration of 1.15 M in a solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed in a volume ratio of 3:7 (EC:EMC).

[0100] Charge and discharge experiments are conducted on the above coin battery using an electrochemical analysis device (Toyo, Toscat-3100) under conditions of 25°C, a voltage range of 2.5V to 4.25V, and a discharge rate of 0.2C. Through this, the initial charge capacity, initial discharge capacity, initial reversible efficiency, and C-rate of the above coin battery are measured.

[0101]

[0102] The measurement results of the experimental examples are shown in Table 1 below.

[0103]

[0104] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 ICPLI(Mol ratio) 1.1 1.2 1.1 1.2 Ni (mol%) 97.7 97.7 97.7 97.7 Co (mol%) 1.0 1.0 1.0 1.0 Mn (mol%) 1.0 1.0 1.0 1.0 Zr (mol%) 0.1 0.1 0.1 Na (ppm) 99 8 26 45 1 S (ppm) 66 37 24 66 37 18 Battery Characteristics Initial Charge Capacity (mAh / g) 238.8 237.6 237.5 237. Initial Discharge Capacity (mAh / g) 213.0 209.5 209.9 210.5 Initial Reversibility Efficiency (%) 89.2 88.2 88.4 88.6 C-rate (0.2C / 0.1C) 201.6 200.7 200.9 201.2 XRD Analysis Results of lithium compounds relative to transition metals Ratio(%) 0.77 0.85 0.93 1.07

Claims

1. Obtaining transition metal hydroxides containing nickel, cobalt, and manganese; A first mixture is heated in an oxygen atmosphere and at a first temperature to obtain a preliminary lithium transition metal oxide; and A second mixture is heated in an oxygen atmosphere and at a second temperature to obtain a lithium transition metal oxide; comprising, The first mixture above includes the transition metal hydroxide and lithium compound, and The second mixture above includes the preliminary lithium transition metal oxide, and The first temperature is within the range of 700 ℃ to 1000 ℃, and A method for manufacturing an anode active material to obtain the above-mentioned preliminary lithium transition metal oxide by heating the above-mentioned first mixture at a heating rate within the range of 0.1 ℃ / min to 1.8 ℃ / min at a temperature within the range of 500 ℃ to 600 ℃.

2. In Paragraph 1, The above preliminary lithium transition metal oxide is to obtain Raising the temperature of the first mixture from a reference temperature to the first temperature; and Maintaining the above first mixture at a first temperature; A method for manufacturing a positive electrode active material in which the above reference temperature is within the range of 10 ℃ to 30 ℃.

3. In Paragraph 1, A method for manufacturing an anode active material in which the first mixture is maintained at the first temperature for 180 to 300 minutes to obtain the above-mentioned preliminary lithium transition metal oxide.

4. In Paragraph 1, The first temperature is within the range of 750 ℃ ​​to 800 ℃, and To obtain the above-mentioned preliminary lithium transition metal oxide, the above-mentioned first mixture is heated at a temperature of 500 ℃ to 600 ℃ at a heating rate within the range of 1 ℃ / min to 1.6 ℃ / min, and A method for manufacturing an anode active material, wherein the first mixture is maintained at the first temperature for 180 to 200 minutes to obtain the above-mentioned preliminary lithium transition metal oxide.

5. In Paragraph 1, A method for manufacturing an anode active material in which the nickel content of the above transition metal hydroxide is 60 mol% or more.

6. In Paragraph 1, The above first mixture further comprises a doping element precursor, and A method for manufacturing a positive electrode active material comprising two or more doping elements selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

7. In Paragraph 1, The above doping elements are a method for manufacturing a positive active material including Ba and Zr.

8. In Paragraph 1, A method for manufacturing an anode active material in which the barium precursor content of the first mixture is within the range of 0.1 mol% to 0.5 mol% based on metal elements excluding lithium among the transition metal hydroxides.

9. In Paragraph 1, A method for manufacturing an anode active material in which the zirconium precursor content of the first mixture is within the range of 0.1 mol% to 0.5 mol% based on metal elements excluding lithium among the transition metal hydroxides.

10. In Paragraph 6, The above second mixture further comprises a doping element precursor, and A method for manufacturing a positive electrode active material comprising two or more doping elements selected from the group consisting of Ba, Zr, Al, Ce, Hf, Ta, Cr, F, Mg, Cr, V, Ti, Fe, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, Ge, Nd, Gd, and Cu.

11. In Paragraph 1, The above second mixture is a method for manufacturing an anode active material that further includes a cobalt precursor.

12. In Paragraph 1, A method for manufacturing an anode active material in which the cobalt precursor content of the second mixture is within the range of 3 mol% to 4 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

13. In Paragraph 1, A method for manufacturing a positive active material in which at least one of the doping element precursors of the second mixture is the same as the doping element precursor of the first mixture.

14. In Paragraph 1, A method for manufacturing a positive electrode active material in which the second temperature is within the range of 650 ℃ to 750 ℃.

15. In Paragraph 3, A method for manufacturing a positive electrode active material in which the ratio of the time for maintaining the first mixture at the first temperature to the time for raising the temperature of the first mixture in obtaining the above-mentioned preliminary lithium transition metal oxide is 0.5 or less.

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