Method for preparing positive electrode active material and positive electrode active material

Abstract

The present disclosure relates to a method for preparing a positive electrode active material, the method comprising the steps of: obtaining a transition metal hydroxide containing 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, wherein the first mixture comprises the transition metal hydroxide and a lithium compound, the second mixture comprises the preliminary lithium transition metal oxide and a boron precursor, the second temperature is in the range of 730 °C to 780 °C, and the boron precursor content of the second mixture is in the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

Description

Method for manufacturing a positive electrode active material and a positive electrode active material

[0001] The present disclosure relates to a method for manufacturing a positive electrode active material and a positive electrode active material.

[0002] Lithium secondary batteries can repeatedly charge and discharge through the intercalation and deintercalation of lithium ions. Lithium secondary 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. Nickel, cobalt, and manganese may be included as transition metals in lithium composite oxides.

[0004] The characteristics of lithium composite oxides can affect the lifespan characteristics and performance of lithium secondary batteries.

[0005] The present disclosure aims to provide a positive electrode active material containing a small amount of residual lithium.

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

[0007] The present disclosure aims to provide a method for manufacturing a positive electrode active material having excellent performance.

[0008] 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; 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 a boron precursor, wherein the second temperature is within the range of 730 °C to 780 °C, and the boron precursor content of the second mixture is within the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

[0009] The above second mixture may further include a cobalt precursor.

[0010] The nickel content of the above transition metal hydroxide may be 60 mol% or more.

[0011] The first mixture further comprises a doping element precursor, and the doping element may include two or more selected from the group consisting of Al, Zr, Ba, 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.

[0012] The above doping elements may include Al and Zr.

[0013] The aluminum precursor content of the first mixture may be in the range of 0.4 mol% to 0.6 mol% based on the transition metal excluding lithium among the transition metal hydroxides.

[0014] The zirconium precursor content of the first mixture may be in the range of 0.1 mol% to 0.3 mol% based on the transition metal excluding lithium among the transition metal hydroxides.

[0015] The cobalt precursor content of the second mixture may be in the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

[0016] The first temperature mentioned above may be in the range of 700 ℃ to 770 ℃.

[0017] The second temperature mentioned above may be in the range of 700 ℃ to 770 ℃.

[0018] The positive electrode active material of the present disclosure comprises: a lithium transition metal oxide comprising nickel, cobalt, manganese, and a doping element; and a coating layer disposed on the surface of the lithium transition metal oxide and comprising a lithium boron oxide; wherein the doping element comprises boron, and the lithium boron oxide content of the positive electrode active material is within the range of 0.3 weight% to 1.6 weight%.

[0019] The nickel content of the above lithium transition metal oxide may be 60 mol% or more.

[0020] The above doping elements may include two or more selected from the group consisting of Al, Zr, Co, Ba, 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.

[0021] The above doping elements may include one or more selected from the group consisting of Al, Zr, and Co.

[0022] The above Al content may be in the range of 0.4 mol% to 0.6 mol%.

[0023] The content of Zr above may be in the range of 0.1 mol% to 0.3 mol%.

[0024] The above positive active material comprises primary particles including the lithium transition metal oxide and secondary particles formed by the aggregation of the primary particles, and the size of the primary particles may be 150 nm or less.

[0025] The present disclosure may provide a positive electrode active material containing a small amount of residual lithium.

[0026] The present disclosure can provide a positive electrode active material capable of improving the lifespan characteristics and battery characteristics of a lithium secondary battery.

[0027] The present disclosure can provide a method for manufacturing a positive electrode active material having excellent performance.

[0028] Figure 1 shows the XRD analysis results of the lithium transition metal oxide of the present disclosure.

[0029] Figure 2 is an enlarged view of a part of Figure 1.

[0030] Figure 3 shows the CP-SEM cross-sectional imaging results of Example 1.

[0031] Figure 4 shows the CP-SEM cross-sectional imaging results of Comparative Example 1.

[0032] Figure 5 shows the CP-SEM cross-sectional imaging results of Comparative Example 2.

[0033] Figure 6 shows the CP-SEM cross-sectional imaging results of Comparative Example 3.

[0034] Figure 7 shows the CP-SEM cross-sectional imaging results of Comparative Example 4.

[0035] Figures 8 and 9 illustrate the results of the electrochemical characteristic evaluation.

[0036] FIG. 10 is an enlarged view of the mAh / g range with a capacity of 200 mAh / g to 220 mAh / g in FIG. 9.

[0037] The present disclosure is described in detail below.

[0038] One embodiment of the present disclosure relates to a method for manufacturing a positive electrode active material.

[0039] The method for manufacturing an anode active material of the present disclosure comprises: obtaining a transition metal hydroxide comprising nickel, cobalt, and manganese; heating a first mixture comprising said transition metal hydroxide and a lithium compound in an oxygen atmosphere and at a first temperature to obtain a preliminary lithium transition metal oxide; and heating a second mixture comprising said preliminary lithium transition metal oxide and a boron precursor in an oxygen atmosphere and at a second temperature to obtain a lithium transition metal oxide; wherein the boron precursor content of the second mixture may be in the range of 0.7 mol% to 1.3 mol%.

[0040] The method for manufacturing an anode active material of 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.

[0041] The first mixture comprises the transition metal hydroxide and the lithium compound. The second mixture comprises the preliminary lithium transition metal oxide and the boron precursor. The second temperature is within the range of 730°C to 780°C. The boron precursor content of the second mixture is within the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

[0042] 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.

[0043] 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.

[0044] Obtaining the above transition metal hydroxide may mean obtaining a commercially available transition metal hydroxide.

[0045] The present disclosure may perform heating a first mixture in an oxygen atmosphere and at a first temperature to obtain a preliminary lithium transition metal oxide. The first mixture may include the transition metal hydroxide and the lithium compound.

[0046] The above lithium compound may be a lithium raw material that reacts with the above transition metal hydroxide to form a lithium transition metal oxide. The above 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. The lithium compound may have a 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) of 0.96 or more, 0.97 or more, 0.98 or more, or 0.99 or more. The lithium compound may have a ratio (Li / Metal) of the number of atoms of lithium (Li) to the total number of atoms of metal elements other than lithium (Metal) in the first mixture of 1.09 or less, 1.08 or less, 1.07 or less, 1.06 or less, 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, or 1.01 or less.

[0047] The first mixture may further include a doping element precursor. The doping element may include two or more selected from the group consisting of Al, Zr, Ba, 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.

[0048] The above doping element can react with the above transition metal hydroxide to dope the above preliminary lithium transition metal oxide.

[0049] The above doping element may include one or more selected from the group consisting of aluminum precursors and zirconium precursors. The aluminum precursor may include one or more selected from the group consisting of Al2O3, Al(OH)3, AlPO4, Al(PO3)3, ZrH2, and Zr(OH)2. The zirconium precursor may include one or more selected from the group consisting of ZrH2 and Zr(OH)2.

[0050] The aluminum precursor content of the first mixture may be in the range of 0.1 mol% to 1.0 mol% based on the transition metal excluding lithium among the metal components constituting the transition metal hydroxide. The aluminum precursor content of the first mixture may be 0.2 mol% or more, 0.3 mol% or more, 0.4 mol% or more, or 0.5 mol% or more based on the total moles of the metal excluding lithium among the metal components constituting the transition metal hydroxide. The aluminum precursor content of the first mixture may be 0.9 mol% or less, 0.8 mol%, 0.7 mol%, 0.6 mol%, or 0.5 mol% or less based on the total moles of the metal excluding lithium among the metal components constituting the transition metal hydroxide. At this time, aluminum can react smoothly with the transition metal hydroxide. As a result, aluminum can be smoothly doped into the preliminary lithium transition metal oxide.

[0051] The zirconium precursor content of the first mixture may be in the range of 0.1 mol% to 0.3 mol% based on the transition metal excluding lithium among the metal components constituting the transition metal hydroxide. The zirconium precursor content of the first mixture may be 0.2 mol% or more based on the total moles of the metal excluding lithium among the metal components constituting the transition metal hydroxide. The zirconium precursor content of the first mixture may be 0.5 mol% or less, 0.4 mol%, or 0.3 mol% or less based on the total moles of the metal excluding lithium among the metal components constituting the transition metal hydroxide. At this time, zirconium can react smoothly with the transition metal hydroxide. As a result, zirconium can be smoothly doped into the preliminary lithium transition metal oxide.

[0052] By satisfying the above range for the zirconium precursor content of the first mixture, zirconium can react smoothly with the transition metal hydroxide. As a result, zirconium can be doped into the preliminary lithium transition metal oxide.

[0053] 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 under an oxygen atmosphere. In obtaining the above-mentioned preliminary lithium transition metal oxide, the first mixture may be heated at a first temperature. The first temperature may be 730°C to 780°C. For example, the first temperature may be 750°C. The first temperature may be set within a preset range so that doping of the first mixture can be carried out smoothly.

[0054] The temperature of the kiln may be increased at a preset rate until the temperature of the kiln reaches the first temperature. The temperature of the kiln may be increased from a reference temperature to the first temperature. The reference temperature may be 10°C to 50°C. When the temperature of the kiln reaches the first temperature, the temperature of the kiln may be maintained at the first temperature for a preset time. The time during which the temperature of the kiln is maintained at the first temperature may be 9 to 11 hours.

[0055] The sum of the time during which the temperature of the above-mentioned kiln is raised and the time during which it is maintained at the first temperature may be approximately 15 to 17 hours. This allows the firing process to proceed properly.

[0056] 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.

[0057] The above lithium transition metal oxide may be obtained in a calcination furnace. The above lithium transition metal oxide may be obtained under an oxygen atmosphere. The above lithium transition metal oxide may be obtained by heating the second mixture at a second temperature.

[0058] The second mixture may include the boron precursor and the preliminary lithium transition metal oxide. The boron precursor and the preliminary lithium transition metal oxide may be mixed and then heated. As a result, boron may be doped into the lithium transition metal oxide. By doping the lithium transition metal oxide with boron, the electrochemical characteristics and capacity characteristics of a battery containing the lithium transition metal oxide may be improved. Additionally, by mixing the boron precursor and the preliminary lithium transition metal oxide together and heating, the crystal size of the primary particles of the lithium transition metal oxide may be prevented from increasing.

[0059] The above boron precursor may include one or more selected from the group consisting of B2O3, H3BO3, B(CH3)3, NaBH4, and Na[(B(C6H5)4)].

[0060] The boron precursor content of the second mixture may be in the range of 0.7 mol% to 1.3 mol%. If the content of the boron precursor is less than 0.7 mol%, the boron content is low and may not react sufficiently with the preliminary lithium transition metal oxide, and the boron may not be sufficiently doped. Additionally, if the content of the boron precursor exceeds 1.3 mol%, boron that did not react with the preliminary lithium transition metal oxide may remain on the surface of the lithium transition metal oxide. Residual unreacted boron may cause a degradation in the lifespan and capacity characteristics of the battery. As a result, the lifespan and capacity characteristics of the battery containing the positive electrode active material may be degraded.

[0061] A portion of the boron precursor may react with the preliminary lithium transition metal oxide. As a result, the lithium transition metal oxide may contain boron inside. A portion of the boron precursor that is not included in the lithium transition metal oxide may form a coating layer on the outer surface of the lithium transition metal oxide.

[0062] The boron included in the coating layer may be a borate-based compound or a lithium borate (LBO)-based compound. Additionally, the boron included in the coating layer may be a complex oxide that is combined with some of the transition metals included in the first mixture.

[0063] The second mixture may further include a cobalt precursor. The content of the cobalt precursor in the second mixture may be in the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide. By including the cobalt within the above content range, the cobalt can react with the preliminary lithium transition metal oxide. Through this, the cobalt can be doped into the lithium transition metal oxide, which is the final product.

[0064] The above cobalt precursor may include one or more selected from the group consisting of CoCl2, Co(NO3)2, CoC2O4, and Co(OH)2.

[0065] The lithium transition metal oxide may be obtained in a calcination furnace. The lithium transition metal oxide may be obtained under an oxygen atmosphere. The lithium transition metal oxide may be obtained by heating the second mixture at a second temperature. The second temperature may be between 730°C and 780°C. For example, the second temperature may be 750°C. The second temperature may be set within a preset range to facilitate the doping of the first mixture. If the second temperature is below 730°C, heat may not be transferred to the interior of the preliminary lithium transition metal oxide, and as a result, the boron precursor may not be doped smoothly. If the second temperature exceeds 780°C, the preliminary lithium transition metal oxide may be excessively calcined, causing the particle size of the preliminary lithium transition metal oxide to increase. Consequently, the lifespan and capacity characteristics of the battery manufactured from the preliminary lithium transition metal oxide may be degraded.

[0066] 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 7 to 9 hours. Through this, the firing process can proceed properly.

[0067] After the temperature of the above-mentioned kiln is maintained at the second temperature, a furnace cooling step can be performed.

[0068] Another embodiment of the present disclosure relates to a positive active material.

[0069] The positive electrode active material of the present disclosure comprises: a lithium transition metal oxide comprising nickel, cobalt, manganese, and a doping element; and a coating layer disposed on the surface of the lithium transition metal oxide and comprising a lithium boron oxide; wherein the doping element comprises boron. The lithium boron oxide content of the positive electrode active material is within the range of 0.3 weight% to 1.6 weight%.

[0070] The lithium transition metal oxide can absorb or release lithium ions. The lithium transition metal oxide may include primary particles and secondary particles formed by the aggregation of the primary particles.

[0071] Here, the primary particle refers to a single grain or crystallite, and the secondary particle refers to an aggregate formed by the aggregation of multiple primary particles. The primary particle may have a rod shape, an elliptical shape, and / or an irregular shape. There may be voids and / or grain boundaries between the primary particles constituting the secondary particle.

[0072] For example, the primary particle may form an internal void by being spaced apart from an adjacent primary particle within the secondary particle. Additionally, the primary particle may form a surface existing within the secondary particle by contacting the internal void without contacting the adjacent primary particle to form a grain boundary. Meanwhile, the surface of the primary particle exposed to the outside, existing on the outermost surface of the secondary particle, forms the surface of the secondary particle.

[0073] The size of the primary particle may be 150 nm or less. If the size of the primary particle is large, it may react actively with the electrolyte. Therefore, it is necessary to appropriately control the size of the primary particle. The present disclosure may form the size of the primary particle to be 150 nm or less. In this case, the performance and lifespan characteristics of a battery containing the primary particle may be improved. The size of the primary particle may refer to the length of the major axis of the primary particle. For example, the length of the point furthest from the outer edge to the outer edge of the primary particle may be the size of the primary particle.

[0074] The primary particles may contain nickel, cobalt, and manganese. The nickel content of the lithium transition metal oxide may be 60 mol% or more. The content of the cobalt and the manganese may differ from each other.

[0075] The content of each of the above nickel, cobalt, and manganese can be measured based on metal elements excluding lithium among the lithium transition metal oxides. As a result, the cathode active material containing the lithium transition metal oxide can exhibit high capacity characteristics.

[0076] The above positive active material may include a coating layer comprising lithium boron oxide. The coating layer may be disposed on the surface of the lithium transition metal oxide. The coating layer may cover at least a portion of the surface of the primary particles (e.g., the interface between the primary particles) and / or the secondary particles formed by the aggregation of the primary particles.

[0077] For example, the coating layer may exist to cover at least a portion of the exposed surface of the primary particle. In particular, the coating layer may exist to cover at least a portion of the exposed surface of the primary particle located at the outermost edge of the secondary particle.

[0078] Accordingly, the coating layer may exist as a layer that continuously or discontinuously coats the surface of the primary particles and / or the secondary particles formed by the aggregation of the primary particles. If the coating layer exists discontinuously, the coating layer may appear as a closed curve on the secondary particles.

[0079] The coating layer may exist not only at least a portion of the interface between the primary particles and the surface of the secondary particles, but also in the internal pores formed inside the secondary particles. The coating layer thus present can contribute to improving the physical and electrochemical properties of the positive electrode active material.

[0080] The coating layer may also exist in the form of a solid solution that does not form a boundary with the primary particles and / or the secondary particles formed by the aggregation of the primary particles, but this is not necessarily the case.

[0081] The lithium boron oxide content of the above-mentioned positive electrode active material may be 0.3 weight% to 1.6 weight%. When the lithium boron oxide content is included within this range, the lifespan characteristics and battery characteristics of the above-mentioned positive electrode active material may be excellent.

[0082] As described above, in the process of manufacturing the positive electrode active material, the preliminary lithium transition metal oxide and the boron precursor may be mixed and heated. In order for the boron precursor to be properly doped, the boron precursor must be included in an amount of 0.7 mol% to 1.3 mol%. As a result, the lithium boron oxide content of the coating layer may be 0.3 wt% to 1.6 wt%.

[0083] The present disclosure is described in more detail below with reference to examples and comparative examples. However, the present disclosure is not limited to examples.

[0084] Preparation Example 1. Preparation of transition metal hydroxide

[0085] Example 1. Anode active material

[0086] Spherical NiO by the co-precipitation method 96 Co 0.02 Ni 0.02 (OH)2 transition metal hydroxides are prepared. Specifically, 25 wt% NaOH and 30 wt% NH4OH (relative to the aqueous sulfuric acid solution) 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 96:2:2 (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, NiO. 96 Co 0.02 Ni 0.02 (OH)2 composition Transition metal hydroxide is obtained.

[0087] Next, the transition metal hydroxide, the lithium raw material, the aluminum precursor, and the zirconium precursor are mixed. Here, LiOH (Li / (Metal) mol ratio = 1.01) is used as the lithium raw material. As the aluminum precursor, Al(OH)3 is used, wherein the aluminum content based on metal elements excluding lithium in the transition metal hydroxide is set to 0.5 mol%. As the zirconium precursor, Zr(OH)2 is used, wherein the zirconium content based on metal elements excluding lithium in the transition metal hydroxide is set to 0.5 mol%. It is used. Afterwards, the kiln is heated to 750°C over 5 hours and 55 minutes while maintaining an oxygen atmosphere. The mixture is further heat-treated for 10 hours and then cooled in the furnace. As a result, a preliminary lithium transition metal oxide is obtained.

[0088] A cobalt precursor and a boron precursor are mixed with the above-mentioned preliminary lithium transition metal oxide. The cobalt precursor uses Co(OH)2, in which the cobalt content based on metal elements excluding lithium in the above-mentioned preliminary lithium transition metal oxide is set to 1.0 mol%. The boron precursor uses H3BO3, in which the boron content based on metal elements excluding lithium in the above-mentioned preliminary lithium transition metal oxide is set to 1.0 mol%.

[0089] Afterward, the temperature is raised to 750°C over 2 hours and 35 minutes while maintaining an oxygen (O2) atmosphere in a kiln. The mixture is further heat-treated for 8 hours and then cooled in the kiln. As a result, a lithium transition metal oxide is obtained.

[0090] Comparative Example 1

[0091] When the above-mentioned pre-lithium transition metal oxide, the above-mentioned Co(OH)2, and the above-mentioned H3BO3 are mixed and then calcined, the temperature of the calcination furnace is controlled to be raised to 700 ℃. Except for this, the same process as in Example 1 is repeated.

[0092] Comparative Example 2

[0093] When the above-mentioned preliminary lithium transition metal oxide is calcined, the same process as in Example 1 is repeated except that the above-mentioned H3BO3 is not added.

[0094] Comparative Example 3

[0095] H3BO3 is mixed in which the boron content based on metal elements excluding lithium among the above-mentioned preliminary lithium transition metal oxides is weighed at 0.25 mol%. Except for this, the same process as in Example 1 is repeated.

[0096] Comparative Example 4

[0097] H3BO3 is mixed in which the boron content based on metal elements excluding lithium among the above-mentioned preliminary lithium transition metal oxides is weighed at 0.50 mol%. Except for this, the same process as in Example 1 is repeated.

[0098] Experimental Example 1. ICP Analysis Method

[0099] 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).

[0100] Experimental Example 2. Measurement of Residual Lithium

[0101] 5 g of the cathode active material prepared in the examples and comparative examples was added to 100 ml of distilled water and stirred for 15 minutes. Afterward, the filtrate was filtered and titrated with 0.1 M hydrochloric acid (HCl). The amounts of residual lithium hydroxide (LiOH) and lithium carbonate (Li2CO3) were calculated using the Warder titration method.

[0102] Experimental Example 3. XRD Analysis of Lithium Transition Metal Oxides

[0103] 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.

[0104] Figure 1 shows the XRD analysis results of a lithium transition metal oxide. Figure 2 is an enlarged view of the region in Figure 1 where 2θ is 100 degrees to 200 degrees. Referring to Figure 2, it is confirmed that among the peaks identified at 2θ of 100 to 120 degrees, the peak of Example 1 has shifted to the left relative to the peaks of Comparative Example 1 and Comparative Example 2. It is presumed that the peak shifted because boron was doped into the lithium transition metal oxide.

[0105] In lithium transition metal oxides, oxygen forms bonds with transition metals and forms oxygen crystal planes. At this time, when boron is doped into the lithium transition metal oxide, the oxygen forming the oxygen crystal planes and boron can form ionic bonds. As a result, the bond between the transition metal and the oxygen is relatively weakened, and accordingly, the distance between the oxygen crystal planes increases slightly, and the peak may shift to the left.

[0106] Experimental Example 4. CP-SEM cross-sectional imaging of lithium transition metal oxide

[0107] 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.

[0108] Figure 3 shows the CP-SEM cross-sectional imaging results of Example 1. Figure 4 shows the CP-SEM cross-sectional imaging results of Comparative Example 1. Figure 5 shows the CP-SEM cross-sectional imaging results of Comparative Example 2. Figure 6 shows the CP-SEM cross-sectional imaging results of Comparative Example 3. Figure 7 shows the CP-SEM cross-sectional imaging results of Comparative Example 4.

[0109] In addition, the diameter of the primary particle was measured using the Ipwin 32 program in the above CP-SEM cross-sectional image.

[0110] Experimental Example 5. Evaluation of Electrochemical Characteristics of a Lithium Secondary Battery

[0111] 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 °C 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).

[0112] 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.

[0113] In addition, a high-temperature life characteristic experiment is conducted on the coin battery at 45°C using the same electrochemical analysis device. Through this, the life characteristic of the coin battery is measured. Charging is carried out in the CC-CV method under conditions of 0.5 C, 4.25 V, and a cut-off of 0.05 C, and discharging is carried out under conditions of 1.0 C and a cut-off of 2.5 V. After one cycle of charging and discharging, the discharge capacity was measured. Subsequently, after 40 cycles of charging and discharging, the discharge capacity was measured again.

[0114] FIGS. 8 and 9 illustrate the results of the electrochemical characteristic evaluation of the present disclosure, FIG. 10 illustrates an enlarged view of the region in FIG. 9 where the capacity is 200 mAh / g to 220 mAh / g, and FIG. 11 illustrates the discharge capacity results of a secondary battery according to 40 cycle repetitions. The measurement results of the experimental examples are shown in Table 1 below.

[0115] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 ICPNi(mol%) 94.424 194.464 694.472 994.43 5794.4195 Co(mol%) 3.060 13.029 13.020 3.0383 73.05862 Mn(mol%) 2.0027 2.003 12.004 12.011 12.0068 Al(mol%) 0.5129 0.5 0300.50280.51470.5149Zr(mol%)0.12250.12410.12500.12430.1261B(ppm)1027-- 329565Residual LithiumLiOH(ppm)178701942782054888Li2CO3(ppm)27013749379442002908BETm 2 / g 0.16 190.14 880.12 820.14 970.16 56 Battery Characteristics Initial Charge Capacity (mAh / g) 243.5 241.8 243.3 244.2 244.5 Initial Discharge Capacity (mAh / g) 214.5 205.12 11.6 213.9 214.6 Initial Reversibility Efficiency (%) 88.1 84.8 87.0 87.6 87.6 C-rate (0.5C / 2.0C) 196.1 190.6 190.11 82.3 178.11 CYC 219.5 212.5 210.5 207.0 212.2 40 CYC 192.1188.5136.0118.5122.7 Particle size ㎛ 109.09 2.5182.6188.8174.2

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 comprises the preliminary lithium transition metal oxide and boron precursor, and The second temperature mentioned above is within the range of 730 ℃ to 780 ℃, and A method for manufacturing an anode active material in which the boron precursor content of the second mixture is within the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

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

3. 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.

4. 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 Al, Zr, Ba, 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.

5. In Paragraph 1, The above doping elements are a method for manufacturing a positive electrode active material containing Al and Zr.

6. In Paragraph 5, A method for manufacturing an anode active material in which the aluminum precursor content of the first mixture is within the range of 0.4 mol% to 0.6 mol% based on the transition metal excluding lithium among the transition metal hydroxides.

7. In Paragraph 5, 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 0.3 mol% based on the transition metal excluding lithium among the transition metal hydroxides.

8. In Paragraph 2, A method for manufacturing an anode active material in which the cobalt precursor content of the second mixture is within the range of 0.7 mol% to 1.3 mol% based on the transition metal excluding lithium in the preliminary lithium transition metal oxide.

9. In Paragraph 1, A method for manufacturing a positive electrode active material in which the first temperature is within the range of 700 ℃ to 770 ℃.

10. In Paragraph 1, A method for manufacturing a positive electrode active material in which the second temperature is within the range of 700 ℃ to 770 ℃.

11. A lithium transition metal oxide comprising nickel, cobalt, manganese, and doping elements; and a coating layer disposed on the surface of the lithium transition metal oxide and comprising lithium boron oxide; wherein the positive electrode active material comprises, The above doping element includes boron, and A positive electrode active material having a lithium boron oxide content within the range of 0.3 weight% to 1.6 weight%.

12. In Paragraph 11, A positive electrode active material having a nickel content of 60 mol% or more of the lithium transition metal oxide.

13. In Paragraph 11, The above doping element comprises two or more types selected from the group consisting of Al, Zr, Co, Ba, 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, forming a positive electrode active material.

14. In Paragraph 13, The above doping element comprises one or more selected from the group consisting of Al, Zr, and Co., forming a positive electrode active material.

15. In Paragraph 14, A positive active material having an Al content within the range of 0.4 mol% to 0.6 mol%.

16. In Paragraph 15, A positive active material having a Zr content within the range of 0.1 mol% to 0.3 mol%.

17. In Paragraph 11, The above positive electrode active material comprises primary particles containing the lithium transition metal oxide and secondary particles formed by the aggregation of the primary particles, and A positive active material having a primary particle size of 150 nm or less.

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