Positive electrode active material, its manufacturing method, and lithium secondary battery including the same

Abstract

To provide a positive electrode active material capable of suppressing the decomposition reaction of an electrolyte on the surface and improving high-temperature life characteristics, a method for manufacturing the same, and a lithium secondary battery including the same.SOLUTION: A positive electrode active material includes a lithium metal oxide and a coating layer located on the surface of the lithium metal oxide, and the coating layer has a peak observed in the range of 1580 cm-1 to 1600 cm-1 during FT-IR measurement, and the average transmittance of the peak is 0.990 to 0.99.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a positive electrode active material, a method for producing the same, and a lithium secondary battery including the same. [Background technology]

[0002] Recently, there has been an explosion in IT mobile devices and small power-driven devices (e-bikes, small EVs, etc.). In response to the sudden increase in demand for electric vehicles with a driving range of over 400 km, The development of high-capacity, high-energy-density secondary batteries is being actively pursued worldwide. To manufacture such a high-capacity battery, a high-capacity positive electrode active material must be used. . The material with the highest capacity among the currently available layered positive electrode active materials is LiNi O2 (275mAh / g), but the structure tends to collapse during charging and discharging, and there is a problem with the oxidation number. However, the thermal stability of these materials is low, making their commercialization difficult.

[0003] To solve this problem, we need to introduce other stable transition metals (C Co and Mn are replaced by ternary N The CM system was developed. However, in the case of ternary NCM, the thermal stability decreases as the Ni content increases. Summary of the Invention [Problem to be solved by the invention]

[0004] In this embodiment, an attempt is made to provide a positive electrode active material in which the decomposition reaction of the electrolyte is suppressed on the surface. This also improves the high-temperature life characteristics. [Means for solving the problem]

[0005] The positive electrode active material according to one embodiment includes a lithium metal oxide and the lithium metal oxide. The coating layer is located on the surface of the A peak is observed in the range of 80 cm-1 to 1600 cm-1, and the average transmittance of the peak is It may contain a first compound having a molecular weight in the range of 0.990 to 0.998.

[0006] According to another embodiment, a method for manufacturing a positive electrode active material includes the steps of: preparing a lithium metal oxide; and forming a coating layer on the surface of the lithium metal oxide, The absorbing layer was observed at 1580 cm during FT-IR measurement. -1 ~1600cm -1 The peak is in the range The first compound is observed, and the transmittance average of the peak is in the range of 0.990 to 0.998. It can include. [Effects of the Invention]

[0007] The positive electrode active material according to one embodiment includes a lithium metal oxide particle having a surface containing a carbon-nitrogen bond. By forming a coating layer containing a compound containing The action of compounds containing carbon-nitrogen bonds contained in the coating layer that come into contact with the solution This makes it possible to suppress the decomposition reaction of the electrolyte on the surface of the positive electrode. This reduction in electrolyte side reactions significantly improves the high-temperature life characteristics of the positive electrode active material. This can be done. [Brief explanation of the drawings]

[0008] [Figure 1] 1 shows the results of FT-IR analysis of the positive electrode active materials prepared in Examples 1 and 2 and Comparative Example 1. [Figure 2a] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 1. [Figure 2b] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 6. [Figure 2c] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 7. [Figure 3a] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 1. [Figure 3b] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 6. [Figure 3c] 1 shows the results of XPS analysis of the positive electrode active material prepared in Example 7. [Figure 4] 1 shows the results of evaluating high-temperature life characteristics of lithium secondary batteries using the positive electrode active materials prepared according to Comparative Example 1, Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the present invention is provided by way of example only. However, the present invention is not limited thereto, and the present invention is defined by the scope of the claims below. will be done.

[0010] The positive electrode active material according to one embodiment includes a lithium metal oxide and a It includes a coating layer located on the surface. In this embodiment, the coating layer has a peak intensity of 1580 cm −1 to 1800 cm −1 in FT-IR measurement. The first compound may have a peak observed in the range of 1600 cm-1. The compound has an average transmittance of the peak in the wavelength range of 0.990 to 0.998, preferably More specifically, it may be in the range of 0.993 to 0.995. When the wavelength range in which the peak of the compound is observed and the average transmittance satisfy the above ranges, the compound is considered to be a positive electrode active material. This effectively suppresses the electrolyte decomposition reaction that occurs on the surface of the material. The high-temperature life characteristics of a lithium secondary battery using the positive electrode active material of the embodiment can be significantly improved. This can be done.

[0011] On the other hand, the coating layer has a peak intensity of 1070cm-1 to 1120cm-1 in FT-IR measurement. 1 range, more specifically, a peak is observed in the range of 1085 cm-1 to 1105 cm-1. The second compound may further include a second compound having the peak in a wavelength range. The average transmittance is in the range of 0.985 to 0.993, more specifically, 0.987 to 0.993 In FT-IR measurement, the wavelength range in which the peak of the second compound is observed and When the average transmittance and the average transmittance satisfy the above ranges, the electrolyte decomposition reaction occurring on the surface of the positive electrode active material As a result, the lithium ion battery using the positive electrode active material of this embodiment can be effectively suppressed. This can significantly improve the high-temperature life characteristics of the lithium secondary battery.

[0012] When the value obtained by dividing the average absorbance of the first compound by the average absorbance of the second compound is A, A may satisfy the following formula 1:

[0013] [Formula 1] 0.72>A = (average absorbance of the first compound) / (average absorbance of the second compound)>0.41 More specifically, the A value is in the range of 0.72>A>0.22 or 0.8>A>0.22. When the value of A is within the above range, the electrolyte dissolution occurring on the surface of the positive electrode active material is The decomposition reaction can be effectively suppressed. This can significantly improve the high-temperature life characteristics of the lithium secondary battery.

[0014] The first compound may be, for example, a compound containing a C—N bond.

[0015] The second compound may be, for example, a compound containing an SOx bond. The SOx bond may be an SO3 or SO4 bond. The surface of the lithium metal oxide is coated with the first compound and the second compound. When a coating layer is formed, it suppresses side reactions with the electrolyte and improves the high-temperature life characteristics of the positive electrode. It is possible to realize an active material.

[0016] The coating layer has a spectrum measured by X-ray photoelectron spectroscopy (XPS). For example, in the range of 398 eV to 404 eV, the range of 166 eV to 173 eV, and At least one peak may be observed in the range of 58 eV to 166 eV. The coating layer contains compounds containing CN bonds and / or compounds containing SOx bonds. This is the result of being

[0017] The positive electrode active material has an average crystalline size (Lc) of It may be in the range of 111 nm to 140 nm, more specifically, 115 nm to 120 nm. When the average crystal grain size of the positive electrode active material satisfies the above range, the capacity retention rate characteristics at high temperatures are improved. It can be improved.

[0018] Meanwhile, the average particle size (D50) of the positive electrode active material according to this embodiment is 5 μm to 20 μm. More specifically, it may be in the range of 10 μm to 20 μm.

[0019] The specific surface area of ​​the positive electrode active material is 0.3 to 1.5 m / g, more specifically, 0.5 to 1.5 m / g. It may be 1.5 m2 / g or in the range of 0.96 to 1.5 m2 / g.

[0020] Meanwhile, in this embodiment, the content of nickel in the metals in the lithium metal oxide is 80 mol. More specifically, the lithium metal oxide may be, for example, It can be expressed in Equation 1.

[0021] [Chemical formula 1] LixNiaCobMncM1dM2eO2 In the above chemical formula 1, M1 and M2 are Zr, Ti, Mg, Al, Ni, Mn, and Z, respectively. n, at least one of Fe, Cr, Mo and W, and x is 0.90_x_1. 07, a is 0.80_a<1, b is 0 <b_0.3、cは0<c_0.3、dは0<d< 0.01, e is 0 <e<0.01であり、a+b+c+d+e=1である。

[0022] In this case, the a is 0.85_a<1, more specifically, 0.90_a<1. good. In addition, the b is 0 <b_0.2または0<b_0.1であってもよく、cは0<c_0 .2 or 0 <c_0.1であってもよい。 At the same time, M1 may be Zr and M2 may be Al. When 2 is Al, the positive electrode active material of this embodiment is Zr is 0.05 to 0.6 parts by weight, and Al is 0.01 to 0.4 parts by weight. It can be included in.

[0023] As in the present embodiment, the nickel content of the metals in the lithium metal oxide is 80% or more, That is, when a in Chemical Formula 1 is 0.80 or more, a positive electrode active material having high output characteristics can be obtained. The positive electrode active material of this embodiment having such a composition can achieve an energy per volume ratio of 1.0 to 1.0. As the energy density increases, the capacity of the battery to which it is applied can be improved, and It is also suitable for use as a

[0024] A method for manufacturing a positive electrode active material according to another embodiment includes the steps of preparing a lithium metal oxide and and forming a coating layer on the surface of the lithium metal oxide.

[0025] At this time, the coating layer has a peak intensity of 1580cm-1 to 1600cm-1 in FT-IR measurement. A peak is observed at 1000 nm, and the transmittance average of the peak is in the range of 0.990 to 0.998. It can include a first compound.

[0026] In addition, the coating layer has a peak intensity of 1070 cm-1 to 1120 cm-1 during FT-IR measurement. A peak is observed in the range of 1, and the average transmittance of the peak is in the range of 0.985 to 0.993. The compound may further comprise a second compound which is

[0027] In this embodiment, the coating layer has the same characteristics as the cathode active material according to the above embodiment. Therefore, this is the same as that described in detail in the positive electrode active material according to an embodiment. However, I will omit it here.

[0028] The lithium metal oxide preparation step may be carried out by a conventional method, for example, by the following method: As described in the embodiment, after preparing the precursor of lithium metal oxide, it is doped. The lithium metal oxide is obtained by mixing it with the starting material, calcining it, cooling it, and grinding it. It is possible.

[0029] Then, forming a coating layer on the surface of the lithium metal oxide. At this time, the step of forming the coating layer may include forming the lithium metal oxide More specifically, the step of washing with water may include washing the coated surface with water. The washing can be carried out using a washing solution containing water and an additive for forming a coating layer.

[0030] The additives include, for example, ammonium sulfate, ammonium cobalt sulfate, ammonium nickel sulfate, ammonium manganese sulfate at least one of aluminum ammonium sulfate and aluminum ammonium sulfate; Good too.

[0031] In the water wash, the additive is converted into Li2CO3, which is dissolved from the lithium metal oxide during washing. Through chemical reaction and heat treatment, a coating layer containing CN bonds and SO bonds is formed on the lithium metal oxide. Therefore, a coating layer can be formed on the surface of the oxide. Compounds containing CN bonds and / or compounds containing SOx bonds produced by the method The high-temperature life characteristics of batteries using positive electrode active materials with a coating layer formed on them are significantly improved. It is possible.

[0032] The content of the additive is 1% by weight to 7% by weight, more specifically, 1% by weight to 1% by weight based on the washing water. If the content of the additive is 1% by weight or more, the content of the additive may be in the range of 1% by weight to 5% by weight. The lifespan can be significantly improved. In addition, the content of additives in the washing solution is 7% by weight or less. If so, the initial resistance at room temperature can be significantly reduced, making the positive electrode active material of this embodiment suitable. The performance of the lithium secondary battery using the same can be further improved.

[0033] In the water washing step, the content ratio of the lithium metal oxide and the washing water is set to lithium by weight. The washing can be carried out by using an aluminum metal oxide:water washing solution in a ratio of 1:1 to 3:1.

[0034] In this embodiment, after the step of washing the lithium metal oxide with water, the washed lithium The method may further include a step of heat treating the aluminum metal oxide after drying.

[0035] The washed lithium metal oxide is dried at a temperature of 80°C to 200°C for 1 hour. This may be carried out for 10 to 30 hours. The temperature and time range is sufficient to remove moisture and other substances present in the food, but is not limited to these. stomach.

[0036] Then, the water-washed lithium metal oxide is heat-treated for, for example, 300 to 400°C. It may be carried out at 700°C, more specifically, in the temperature range of 400 to 600°C, for 3 to 10 hours. Alternatively, the reaction may be carried out in an air, oxygen (O2) or nitrogen (N2) atmosphere. In this embodiment, when the heat treatment temperature satisfies the above range, the high-temperature life characteristics can be significantly improved. There is an advantage to being able to do this.

[0037] Such process conditions will be explained in more detail in the examples below.

[0038] In another embodiment of the present invention, a positive electrode comprising the positive electrode active material according to the embodiment of the present invention described above. a negative electrode including a negative electrode active material, and a lithium-ion battery including an electrolyte positioned between the positive electrode and the negative electrode. We provide a rechargeable battery.

[0039] The description of the positive electrode active material is omitted since it is the same as that of the embodiment of the present invention described above. .

[0040] The positive electrode active material layer may include a binder and a conductive material.

[0041] The binder serves to adhere the positive electrode active material particles to each other well and to collect current. It helps to adhere well to the body.

[0042] The conductive material is used to impart conductivity to the electrodes, and the battery Any material that is electronically conductive and does not cause chemical changes can be used. be.

[0043] The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector. The material layer includes a negative electrode active material.

[0044] The negative electrode active material is a material capable of reversibly intercalating / deintercalating lithium ions. Lithium metal, alloys of lithium metal, and lithium Materials that can be doped and dedoped include transition metal oxides.

[0045] The lithium ions are reversibly intercalated / deintercalated. The materials that can be used are carbon materials that are generally used in lithium ion secondary batteries. Any carbon-based negative electrode active material can be used. The carbon material may be crystalline carbon, amorphous carbon, or a combination of both.

[0046] The lithium metal alloy includes lithium and Na, K, Rb, Cs, Fr, Be, M g, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn? An alloy of a metal selected from the group consisting of:

[0047] Examples of substances capable of doping and undoping lithium include Si, SiOx (0 < x < 2), Si-Y alloys (where Y is selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements , Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn, SnO2, Sn-Y (where Y is selected from the group consisting of alkali metals, a lkali earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), etc. Examples of the transition metal oxides include vanadium oxides, lithium vanadium oxides, etc. The negative electrode active material layer also contains a binder and may optionally further contain a conductive material. The binder serves to make the negative electrode active material particles adhere well to each other and also to make the negative electrode active material adhere well to the current collector.

[0048] The conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any material that is an electron conductive material and does not cause a chemical change can be used. Examples of the current collector that can be used include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam ( foam), copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0049] The negative electrode and the positive electrode are prepared by mixing the active material, the conductive material, and the binder in a solvent to produce an active material composition.

[0050]

[0051]

[0052] The composition is then applied to a current collector to produce the electrode. Since this is a well-known matter, detailed explanation will be omitted in this specification. Examples of suitable amines include, but are not limited to, ethyl pyrrolidone.

[0053] The electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0054] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move. Fulfill this.

[0055] The lithium salt is dissolved in an organic solvent to serve as a source of lithium ions in the battery. It enables basic lithium secondary battery operation and transfers lithium ions between the positive and negative electrodes. It is a substance that plays a role in promoting movement.

[0056] Depending on the type of lithium secondary battery, a separator may be present between the positive electrode and the negative electrode. Such separators include polyethylene, polypropylene, polyvinylidene fluoride, and the like. A polyethylene / polypropylene two-layer film can be used. separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene Mixed multilayer films such as PET / polyethylene / polypropylene triple layer separators can be used. Of course.

[0057] Lithium secondary batteries are classified into lithium-ion batteries, lithium-ion batteries, and lithium-ion batteries depending on the type of separator and electrolyte used. They can be classified into lithium ion polymer batteries and lithium polymer batteries, and are cylindrical in shape. They can be classified into square, coin, pouch, etc., and are available in bulk and thin film types depending on the size. The structure and manufacturing methods of these batteries are widely known in the field. A detailed explanation will be omitted.

[0058] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the present invention is provided by way of example only. However, the present invention is not limited thereto, and the present invention is defined by the scope of the claims below. will be done. [Example]

[0059] (Example 1) Preparation of 88 mol% Ni positive electrode active material 1) Preparation of positive electrode active material precursor NiSO4·6H2O is the nickel source material, and CoSO is the cobalt source material. The manganese source material was MnSO4·H2O. The metal salts were dissolved in distilled water to prepare 2.5 M aqueous solutions. After preparing the coprecipitation reactor, N2 was supplied to prevent oxidation of metal ions during the coprecipitation reaction. Purging was performed and the reactor temperature was maintained at 50°C. The coprecipitation reactor was charged with an aqueous metal salt solution and NH4(OH) as a chelating agent. NaOH was used to adjust the pH. The precipitate obtained by the coprecipitation process was filtered. After filtering and washing with distilled water, the cathode active material precursor was prepared by drying in an oven at 100°C for 24 hours. It was created. The composition of the prepared precursor is (Ni0.88Co0.095Mn0.025)(OH)2 The average particle size (D50) was 14.8 μm.

[0060] 2) Manufacturing of positive electrode active material Based on 1 mole of the positive electrode active material precursor prepared in 1), (battery grade) 1.05 moles, Zr 3,400 ppm ZrO2 (Aldrich, 4N), and Al 280 ppm Al(OH)3 (Al The mixture was prepared by uniformly mixing the above ingredients. The mixture was charged into a tube furnace and heated under oxygen flow. After firing, the mixture was cooled to room temperature and then pulverized to produce a fired powder. Next, for the washing process, add ammonium hydroxide to 100g of distilled water (DI water). 1 g of sulfate was added and stirred for 1 minute to prepare a water wash solution. 100 g of the fired powder was added to the water washing solution, stirred for 10 minutes, and then filtered. The filtered sintered powder was dried in a chamber at 100°C or higher, and then subjected to oxygen atmosphere and 40 After heat treatment at 0°C for 3 hours, a positive electrode active material was finally obtained.

[0061] (Examples 2 to 7, Comparative Example 1, and Reference Examples 1 and 2) The composition of the washing solution and the heat treatment conditions of the fired powder filtered after washing are shown in Table 1 below. A positive electrode active material was prepared in the same manner as in Example 1, except that the temperature was adjusted to be as follows.

[0062] [Table 1]

[0063] (Experimental Example 1) FT-IR (Fourier-transform infrared) spectroscopy) analysis The positive electrode active materials prepared in Examples 1 and 2 and Comparative Example 1 were analyzed by FT-IR (F Ourier-transform infrared spectroscopy The results of the analysis are shown in Figure 1.

[0064] Referring to the results of Examples 1 and 2 in FIG. 1, 1580 As the ammonium sulfate content increases in the wavelength range of cm-1 to 1600 cm-1, It can be seen that the transmittance decreases. Also, S=O symmetric st Similarly, in the wavelength range of 1070 cm-1 to 1120 cm-1, which shows retch, As the content of ammonium sulfate increased, the permeability decreased. As the sulfate content increases, the permeability measured through the coating layer of the positive electrode active material decreases. In this case, the high-temperature life characteristics of the lithium secondary battery can be dramatically improved.

[0065] On the other hand, in Comparative Example 1, the coating layer was not formed when the washing step was carried out using only distilled water. In the case of the positive electrode active material prepared in Comparative Example 1, the peaks of 1580 cm-1 to 1600 cm-1 A peak is observed in the wavelength range of 1070 cm-1 to 1120 cm-1. It can be seen that almost no peaks are observed in this region.

[0066] (Experimental Example 2) XPS (X-ray Photoelectron Spectroscopy) opy) analysis The positive electrode active materials prepared in Examples 1 and 6 to 7 were subjected to XPS (X-ray diffraction). y Photoelectron Spectroscopy) and the results This is shown in Figures 2a to 2c and 3a to 3c.

[0067] Referring to Figures 2a to 2c, the binding energy is 4 The N1s peak at around 0.005 eV was observed in the C-N bond state. Referring to Fig. 1, the S2p peak around 170.2 eV is observed in the SOx (x: 3–4) bond state. Therefore, the positive electrode active material according to the present embodiment contains a C-N bond in the coating layer. It can be seen that the compounds include those containing SOx bonds.

[0068] (Experimental Example 3) Measurement of the average particle size of the positive electrode active material For the positive electrode active materials produced in Comparative Example 1, Examples 1 to 7, and Reference Examples 1 and 2, The average particle size (D50, μm) was measured using a particle size analyzer. The results are shown in Table 2 below. did.

[0069] (Experimental Example 4) Measurement of the specific surface area of ​​the positive electrode active material For the positive electrode active materials produced in Comparative Example 1, Examples 1 to 4, and Reference Examples 1 and 2, A BET measurement instrument (QuantaChrome, Autosorb-iQ / MP) was used. The specific surface area was measured, and the results are shown in Table 2 below.

[0070] (Experimental Example 5) XRD (X-ray diffraction) analysis For the positive electrode active materials produced in Comparative Example 1, Examples 1 to 7, and Reference Examples 1 and 2, The crystalline size was measured by X-ray diffraction using CuKα radiation. e) were measured and are shown in Table 2 below. Referring to Table 2 below, in the case of the positive electrode active materials according to Examples 1 to 4, the average crystal grain size was 1 It can be confirmed that the range of 11 nm to 140 nm is satisfied.

[0071] (Experimental Example 6) Electrochemical Characterization The positive electrode active materials prepared in Comparative Example 1, Examples 1 to 7, and Reference Examples 1 and 2 were used. After fabrication of the 032 coin-type half-cells, electrochemical evaluation was performed.

[0072] (1) Coin cell half cell manufacturing Specifically, the positive electrode active material, polyvinylidene fluoride binder (product name: KF11 00) and Denka Black conductive material were mixed in a weight ratio of 92.5:3.5:4. The mixture was dissolved in N-methyl-2-pyrrolidone (N-Methyl The resulting mixture was added to a solvent (2-pyrrolidone) to prepare a cathode active material slurry. The slurry was applied to the positive electrode current collector using a doctor blade. The coating was applied to an aluminum foil (thickness: 15 μm) and dried. The positive electrode was then rolled to prepare a positive electrode. The loading of the positive electrode was about 14.6 mg / cm. 2 Yes The rolling density was approximately 3.1 g / cm3. The positive electrode, a lithium metal negative electrode (thickness 200 μm, Honzo metal), and an electrolyte 2032 coin cell half cells were fabricated in the usual manner using polypropylene separators. The electrolyte was 1M LiPF6 dissolved in ethylene carbonate, dimethyl carbonate, and ethylene carbonate. A mixed solvent of ethylene methyl carbonate (EC:DMC:EMC = 3:4) was used. 3% by volume to prepare a mixed solution, and then vinylene carbonate (VC) 1 It was used at 0.5% by weight.

[0073] (2) 45℃ high temperature cycle characteristic evaluation The coin-type half cell manufactured in (1) above was aged at room temperature (25°C) for 10 hours (ag After that, a charge / discharge test was carried out. The capacity evaluation was based on a standard capacity of 215mAh / g, and the charge / discharge conditions were CC / CV2.5 to 4.2. 5V, 1 / 20C cut-off applied. Initial capacity is 0.2C charge / 0.2C discharge. The high-temperature cycle life characteristics were measured under the conditions of 0.5C charge / 0.5C discharge at high temperature (45°C). After measuring 50 times under the same conditions, the retention rate of the 50th capacity relative to the first capacity is shown in Figure 4 and Table 2 below. Ta.

[0074] Referring to Table 2 and FIG. 4, CN and SOx (x: 3 to 4) bonds were formed on the surface of the positive electrode active material. In the case of Examples 1 and 2 in which a coating layer including a fluorine-containing compound is present, such a coating layer It was confirmed that the high temperature cycle life was significantly increased compared to Comparative Example 1 where no It is possible.

[0075] (3) Initial DC resistance characteristics evaluation at room temperature (25°C) The coin-type half cell manufactured in (1) above was aged at room temperature (25°C) for 10 hours (ag After that, a charge / discharge test was carried out. The capacity evaluation was based on a standard capacity of 215mAh / g, and the charge / discharge conditions were CC / CV2.5 to 4.2. 5V, 1 / 20C cut-off applied. Initial capacity is 0.2C charge / 0.2C discharge. The initial DC resistance at room temperature was 4.25V at 0.2C, and the discharge current was 0.2C at 100% charge. After the current was applied, the voltage fluctuation was measured for 60 seconds and calculated. The results are shown in Table 2.

[0076] Referring to Table 2, the results are as follows: Compared with Comparative Example 1, in which no additives were used in the washing process, the results are as follows: In Examples 1 to 7 and Reference Examples 1 and 2 in which the positive electrode active materials were prepared using It can be seen that the resistances all decreased significantly. The initial resistance values ​​of the positive electrode active materials of Examples 1 to 7 satisfying the temperature range of 0°C are It was confirmed that the positive electrode active materials of Reference Examples 1 and 2 prepared under the same conditions were even better. It can be recognized.

[0077] [Table 2]

[0078] The present invention is not limited to the above embodiments and may be manufactured in various different forms. A person having ordinary skill in the art to which the present invention pertains will understand the technical concept and essential features of the present invention. It should be understood that the invention may be embodied in other specific forms without altering its features. Therefore, the above-described embodiments are illustrative in all respects and are not limiting. It must be understood that:

Claims

1. lithium metal oxide; and a coating layer located on the surface of the lithium metal oxide; Including, The coating layer had a wavelength of 1580 cm when measured by FT-IR. －１ ~1600cm －１ A peak is observed in the range of 1070 cm when measured by FT-IR, and the transmittance average of the peak is in the range of 0.990 to 0.

998. －１ ~1120cm －１ and a second compound having a peak observed in the range of 0.985 to 0.993, A positive electrode active material, wherein A satisfies the following formula 1, where A is a value obtained by dividing the average absorbance of the first compound by the average absorbance of the second compound: [Formula 1] 0.72>A=(average absorbance of first compound) / (average absorbance of second compound)>0.41 (In the above formula 1, the absorbance of the first compound is 1 minus the transmittance value of the first compound, and the transmittance of the second compound is 1 minus the transmittance value of the second compound.)

2. The positive electrode active material according to claim 1 , wherein the first compound is a compound containing a C-N bond.

3. The positive electrode active material according to claim 1 , wherein the second compound is a compound containing an SO x bond.

4. The coating layer is 2. The positive electrode active material according to claim 1, wherein a peak is observed in at least one of the ranges of 398 eV to 404 eV, 166 eV to 173 eV, and 158 eV to 166 eV in a spectrum measured by X-ray photoelectron spectroscopy (XPS).

5. 2. The positive electrode active material of claim 1, wherein the content of nickel in the metal in the lithium metal oxide is 80 mol % or more.

6. providing a lithium metal oxide; and forming a coating layer on the surface of the lithium metal oxide; Including, The coating layer had a wavelength of 1580 cm when measured by FT-IR. －１ ~1600cm －１ A peak is observed in the range of 1070 cm when measured by FT-IR, and the transmittance average of the peak is in the range of 0.990 to 0.

998. －１ ~1120cm －１ and a second compound having a peak observed in the range of 0.985 to 0.993, The step of forming the coating layer comprises: washing the lithium metal oxide with water; The water washing step includes: The washing is performed using a water washing solution containing water and an additive for forming the coating layer, The method for producing a positive electrode active material, wherein the additive is at least one of ammonium sulfate, ammonium cobalt sulfate hexahydrate, ammonium nickel sulfate, ammonium manganese sulfate, and aluminum ammonium sulfate.

7. The content of the additive is The method for producing a positive electrode active material according to claim 6, wherein the amount of the water is in the range of 1% by weight to 7% by weight based on the water washing solution.

8. After the water washing step, The method further comprises the step of drying the washed lithium metal oxide and then heat-treating the same; 7. The method of claim 6, wherein the heat treatment is performed at a temperature in the range of 400° C. to 600° C. for 3 to 10 hours.

9. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 5; a negative electrode including a negative electrode active material; and an electrolyte located between the positive electrode and the negative electrode.

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