Positive electrode active material, method for manufacturing the same, positive electrode containing the same, and lithium secondary battery

Abstract

The positive electrode active material according to the present invention comprises a lithium composite transition metal oxide in a pseudo-single particle form, which is a single particle consisting of one nodule or a composite of 40 or fewer nodules, and in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, and a tungsten-containing coating layer formed on the surface of the lithium composite transition metal oxide, wherein the positive electrode active material is pretreated by immersing it in deionized water at 25°C for 1 hour, and then analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) to measure the ratio of moles of lithium to moles of tungsten (Li / W) is 30 to 45.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0085169 filed on June 30, 2023, and Korean Patent Application No. 10-2024-0084066 filed on June 26, 2024, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety.

[0002] The present invention relates to a positive electrode active material, a method for manufacturing the same, a positive electrode including the same, and a lithium secondary battery.

Background Art

[0003] A lithium secondary battery generally includes a positive electrode, a negative electrode, a separator, and an electrolyte, and the positive electrode and the negative electrode include an active material capable of intercalating and deintercalating lithium ions.

[0004] As the positive electrode active material of a lithium secondary battery, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (such as LiMnO2 or LiMnO4), lithium iron phosphate compound (LiFePO4), etc. have been used. Among these, lithium cobalt oxide has the advantages of a high operating voltage and excellent capacity characteristics, but the price of cobalt as a raw material is high, the supply is unstable, and it is difficult to apply commercially to large-capacity batteries. Lithium nickel oxide has poor structural stability and it is difficult to achieve sufficient life characteristics. On the other hand, lithium manganese oxide is excellent in stability but has a problem of inferior capacity characteristics. Therefore, in order to complement the problems of lithium transition metal oxides containing Ni, Co, or Mn alone, lithium composite transition metal oxides containing two or more transition metals have been developed. Among them, lithium nickel cobalt manganese oxide containing Ni, Co, and Mn is widely used in the battery field of electric vehicles.

[0005] In the case of single-particle positive electrode active materials, compared to conventional secondary-particle positive electrode active materials, the contact area with the electrolyte is smaller, resulting in fewer side reactions with the electrolyte, superior particle strength, and less particle cracking during electrode manufacturing. Therefore, applying single-particle positive electrode active materials offers the advantage of superior gas generation characteristics and lifespan characteristics.

[0006] However, conventional single-particle lithium composite transition metal oxides have problems with lithium mobility, lower battery capacity, and inferior output characteristics compared to conventional secondary-particle lithium composite transition metal oxides, because the primary particle size is relatively larger and the interfaces between primary particles that serve as lithium ion diffusion pathways are smaller. Therefore, high-voltage operation is necessary to realize high-capacity batteries.

[0007] However, while NCM-based lithium composite transition metal oxides can achieve relatively stable performance at drive voltages of 4.3V or less, when the drive voltage exceeds 4.35V, side reactions with the electrolyte become serious, causing transition metal ions to dissolve and rapidly degrading battery performance. It is known that this performance degradation becomes even more severe at higher temperatures.

[0008] Therefore, there is a need to develop cathode active materials of NCM-based lithium composite transition metal oxides in single-particle and / or pseudo-single-particle form that exhibit excellent initial efficiency and rate characteristics at high voltages of 4.35V or higher. [Overview of the project] [Problems that the invention aims to solve]

[0009] The present invention aims to provide a positive electrode active material in single-particle and / or pseudo-single-particle form that has excellent initial efficiency and rate characteristics at high voltages of 4.35V or higher. [Means for solving the problem]

[0010] On one side, the present invention provides a cathode active material comprising a pseudo-single particle form lithium composite transition metal oxide in which the nickel content among all metals other than lithium is 50 mol% to 80 mol% and which is a single particle composed of one single module or a composite of 40 or less modules, and a tungsten-containing coating layer formed on the surface of the lithium composite transition metal oxide. After pretreatment under the condition of immersing the cathode active material in deionized water at 25°C for 1 hour, the ratio (Li / W) of the number of moles of lithium to the number of moles of tungsten measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) is 30 to 45.

[0011] The tungsten-containing coating layer can include a crystal phase including at least one selected from the group consisting of Li2WO4, Li6WO6, Li7WO6, Li6W2O9, and Li5W2O9.

[0012] The number of moles of lithium can be 150 mmol / kg to 250 mmol / kg.

[0013] The number of moles of tungsten can be 3 mmol / kg to 9 mmol / kg.

[0014] The lithium composite transition metal oxide can have a composition represented by the following Chemical Formula 1. [Chemical Formula 1] Li a Ni b Co c M 1 d M 2 e O2 In Chemical Formula 1, M 1 is at least one selected from the group consisting of Mn and Al, and M 2is at least one selected from the group consisting of Ti, Mg, Zr, Y, Ba, Ca, Zr, Sr, W, Ta, Nb, and Mo, and 1.0 ≤ a ≤ 1.5, 0.5 ≤ b ≤ 0.8, 0 <c≦0.3、0<d≦0.3、0≦e≦0.2である。

[0015] The positive electrode active material has a BET specific surface area of ​​0.50 m². 2 / g~1.20m 2 It can be / g

[0016] The D of the positive electrode active material 50 This can be between 3.0 μm and 6.0 μm.

[0017] The tungsten-containing coating layer further contains aluminum, and after pretreatment of the positive electrode active material by immersing it in deionized water at 25°C for 1 hour, the number of moles of aluminum can be measured by analysis using inductively coupled plasma optical emission spectroscopy (ICP-OES) to be between 1000 mmol / kg and 3000 mmol / kg.

[0018] The tungsten-containing coating layer may further contain one or more coating elements selected from the group consisting of Al, Ti, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S.

[0019] In other aspects, the present invention provides a method for producing a positive electrode active material, comprising the steps of mixing a lithium composite transition metal oxide in a pseudo-single particle form, which is a single particle consisting of one nodule or a composite of 40 or fewer nodules, and in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, with a tungsten-containing raw material, and heat-treating the mixture at a temperature of 410°C to 490°C to form a tungsten-containing coating layer on the surface of the lithium composite transition metal oxide, wherein the positive electrode active material is pre-treated by immersing it in deionized water at 25°C for 1 hour, and then analyzed by inductively coupled plasma spectroscopy (ICP-OES) to determine that the ratio of moles of lithium to moles of tungsten (Li / W) is 30 to 45.

[0020] The tungsten-containing raw material is WO3, Li3WO4 and (NH4) 10 W 12 O 41 It can be one or more types selected from the group consisting of 5H2O.

[0021] The tungsten-containing raw material can be mixed in an amount of 1,000 ppm to 6,000 ppm relative to the total weight of the positive electrode active material.

[0022] The aforementioned heat treatment can be carried out for 3 to 7 hours.

[0023] The heat treatment may further include a step of mixing aluminum raw materials.

[0024] The aluminum raw material can be one or more selected from the group consisting of Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3, and aluminum halides.

[0025] The aforementioned aluminum-containing raw material can be mixed in an amount of 400 ppm to 3000 ppm relative to the total weight of the positive electrode active material.

[0026] In other respects, the present invention provides a positive electrode containing the positive electrode active material described above, and a lithium secondary battery containing the positive electrode. The lithium secondary battery can have a charge termination voltage of 4.35V or higher when in operation. [Effects of the Invention]

[0027] The positive electrode active material according to the present invention, when the nickel content in the lithium composite transition metal oxide in single particle form and the ratio of lithium content to tungsten content (Li / W) in the positive electrode active material, measured by inductively coupled plasma spectroscopy (ICP-OES), contains a large amount of crystalline phase that undergoes oxidation-reduction reactions at high voltages of 4.35V or higher, resulting in improved capacity and stable operation. [Modes for carrying out the invention]

[0028] The terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0029] In this invention, "single particle" refers to a particle consisting of one single nodule. In this invention, "pseudo-single particle" refers to a composite particle formed of 40 or fewer nodules.

[0030] In the present invention, "nodule" means a particle unit body that constitutes a single particle or a pseudo-single particle. The nodule can be a single crystal lacking crystalline grain boundaries, or a polycrystalline material in which no grain boundaries are visible when observed with a scanning electron microscope (SEM) at a field of view of 5,000 to 20,000 times. The average particle size of the nodule can be measured as the arithmetic mean of the particle sizes of each nodule measured using a scanning electron microscope (SEM).

[0031] In this invention, "secondary particle" refers to a particle formed by the aggregation of several tens to hundreds of primary particles. More specifically, a secondary particle is an aggregate of 40 or more primary particles.

[0032] As used in this invention, the term "particle" may include one or all of the following: single particles, pseudo-single particles, primary particles, nodules, and secondary particles.

[0033] In the present invention, "D 50 " refers to the particle size at the 50% reference of the volume cumulative particle size distribution of the positive electrode active material. 50 This can be measured using the laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac MT 3000), irradiated with ultrasound at approximately 28 kHz at an output of 60 W, and then measured by obtaining a volume-cumulative particle size distribution graph and determining the particle size corresponding to 50% of the volume-cumulative amount.

[0034] The term "driving voltage" used in this invention refers to the voltage at which lithium ions are desorbed when a voltage is applied, and more specifically, it may refer to the voltage at which the desorbed lithium ions move to the negative electrode.

[0035] In this invention, the "specific surface area" is measured by the BET method, and specifically, it can be calculated from the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) using BELSORP-mino II manufactured by BEL Japan.

[0036] In the present invention, "Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES)" is a method for measuring the lithium and tungsten content on the surface of a cathode active material by analyzing the filtered filtrate after immersing a cathode active material sample in deionized water at 25°C for one hour. The ICP-OES can be performed using methods commonly used in this field.

[0037] positive electrode active material The positive electrode active material according to the present invention will be described below.

[0038] The positive electrode active material according to the present invention comprises (1) a lithium composite transition metal oxide in single-particle or pseudo-single-particle form, and (2) a coating layer formed on the surface of the lithium composite transition metal oxide.

[0039] Specifically, the coating layer contains tungsten, and after pretreatment by immersing the positive electrode active material according to the present invention in deionized water at 25°C for 1 hour, the ratio of moles of lithium to moles of tungsten (Li / W), measured by inductively coupled plasma spectroscopy (ICP-OES), satisfies the range of 30 to 45.

[0040] (1) Lithium composite transition metal oxide The lithium composite transition metal oxide is in a single particle form consisting of one single nodule or a pseudo-single particle form consisting of 40 or fewer nodules, specifically 2 to 30, and more specifically 2 to 20. Compared to existing lithium composite transition metal oxides in a secondary particle form where tens to hundreds of primary particles are aggregated, these single-particle and / or pseudo-single-particle lithium composite transition metal oxides have higher particle strength and therefore experience less particle cracking during rolling.

[0041] Furthermore, in the case of lithium composite transition metal oxides in single-particle or pseudo-single-particle form according to the present invention, the number of lower-component elements (i.e., nodules) constituting the particles is small, so the volume of the primary particles changes less due to expansion and contraction during charging and discharging, and as a result, the occurrence of cracks inside the particles is also significantly reduced.

[0042] On the other hand, the lithium composite transition metal oxide can have a composition in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, specifically 50 mol% to 75 mol%, and more specifically 55 mol% to 75 mol% or 55 mol% to 70 mol%. If the nickel content exceeds 80 mol%, even if a tungsten-containing coating layer is formed, the lifetime characteristics may rapidly deteriorate at high voltages of 4.35 V or higher. If the nickel content is less than 50 mol%, the capacity decreases, making it difficult to achieve the desired electrochemical properties.

[0043] More specifically, the lithium composite transition metal oxide may have a composition represented by the following [Chemical Formula 1].

[0044] [Chemical formula 1] Li a Ni b Co c M 1 d M 2 e O2

[0045] In the above chemical formula 1, M 1is at least one selected from the group consisting of Mn and Al, specifically, Mn or a combination of Mn and Al, M 2 is at least one selected from the group consisting of Ti, Mg, Zr, Y, Ba, Ca, Zr, Sr, W, Ta, Nb, and Mo. M 2 The element is not necessarily included, but when included in an appropriate amount, it can play a role in promoting grain growth during firing or improving crystal structure stability.

[0046] The above-mentioned a represents the molar ratio of lithium in the lithium composite transition metal oxide, and it can be 1.0 ≦ a ≦ 1.5, 1.0 ≦ a < 1.5, or 1.0 ≦ a ≦ 1.2. When the molar ratio of lithium satisfies the above range, a stable layered crystal structure can be formed.

[0047] The above-mentioned b represents the molar ratio of nickel among all the metals other than lithium in the lithium composite transition metal oxide, and it can be 0.5 ≦ b ≦ 0.8, 0.50 ≦ b ≦ 0.75, 0.55 ≦ b ≦ 0.75, or 0.55 ≦ b ≦ 0.70. As the content of nickel among the transition metals increases, a higher capacity can be realized. Therefore, a nickel content of 0.5 or more is more advantageous for realizing a high capacity. However, as the nickel content increases, there are problems such as a decrease in the thermal stability of the positive electrode active material and the elution of transition metals due to contact with the electrolyte. Therefore, when the nickel content is controlled to 0.5 to 0.8 and a tungsten-containing coating layer is included on the surface of the lithium composite transition metal oxide as in the present invention, the tungsten-containing coating layer can effectively block the electrolyte and the positive electrode active material, so that excellent stability can also be realized in the positive electrode active material.

[0048] The above-mentioned c represents the molar ratio of cobalt among all the metals other than lithium in the lithium composite transition metal oxide, and it can be 0 < c ≦ 0.3, 0 < c < 0.3, 0 < c < 0.2, or 0 < c < 0.18. When the molar ratio of cobalt satisfies the above range, good resistance characteristics and output characteristics can be realized.

[0049] The above d is M, which is the total amount of metal other than lithium in the lithium composite transition metal oxide. 1 The molar ratio is shown, 0 <d≦0.3、0<d<0.3、0<d<0.2、または0<d<0.18であることができる。M 1 When the molar ratio satisfies the aforementioned range, the structural stability of the positive electrode active material can be improved.

[0050] The aforementioned e is M, which is the total amount of metal other than lithium in the lithium composite transition metal oxide. 2 This indicates the molar ratio of elements and can be 0 ≤ e ≤ 0.2, 0 ≤ e ≤ 0.15, or 0 ≤ e ≤ 0.1. 1 When present in appropriate amounts, it can promote grain growth during firing or improve crystalline structure stability.

[0051] (2) Tungsten-containing coating layer The positive electrode active material according to the present invention includes a tungsten-containing coating layer formed on the surface of a lithium composite transition metal oxide in single-particle or pseudo-single-particle form.

[0052] In the case of single-particle or pseudo-single-particle cathode active materials, lithium diffusion resistance is higher compared to conventional secondary-particle cathode active materials. Therefore, when a conventional coating layer is applied to the surface of a single-particle cathode active material, the problem of power reduction due to increased resistance becomes even more serious.

[0053] On the other hand, lithium nickel cobalt manganese oxides can achieve relatively stable performance at drive voltages of 4.3V or less, but when the drive voltage exceeds 4.35V, side reactions with the electrolyte become serious, transition metal ions dissolve, and the battery performance deteriorates rapidly. It is known that this deterioration in performance becomes even more severe at higher temperatures.

[0054] Ni-based positive electrode active materials have a high capacity because the nickel content is higher than that of other transition metals among the transition metals that make up the positive electrode active material, but unstable nickel is present on the surface of the positive electrode active material. 3+Ni 4+ A limitation is that it exhibits structural instability due to ions. To overcome this structural instability, various techniques for modifying the surface of the positive electrode active material are being researched.

[0055] Therefore, the inventors have devised a method to select a positive electrode active material that has the effect of improving capacity while stably operating at a high voltage of 4.35V or higher. This method involves pre-treating the positive electrode active material by immersing it in deionized water at 25°C for 1 hour, and then controlling the ratio of moles of lithium to moles of tungsten (Li / W), which is measured by analysis using inductively coupled plasma spectroscopy (ICP-OES). In this case, they found that a large number of crystalline phases that undergo oxidation-reduction reactions at high voltages are included, resulting in a capacity improvement effect, which can be useful in improving the performance of the battery.

[0056] The coating layer may contain tungsten (W) as a coating element. After pretreatment of the positive electrode active material according to the present invention by immersing it in deionized water at 25°C for 1 hour, the ratio of moles of lithium to moles of tungsten (Li / W), measured by inductively coupled plasma spectroscopy (ICP-OES), can be 30 to 45, specifically 30 to 43, and more specifically 30 to 40. If the ratio of moles of lithium to moles of tungsten (Li / W) within the above range is less than 30 or greater than 45, the proportion of Li2WO4 and Li7WO6, which are crystalline phases in which Li insertion and deinsertion are difficult, increases. In this case, when Li insertion and deinsertion occur, the possibility of structural collapse increases, which can lead to a decrease in battery performance.

[0057] On the other hand, when the ratio of moles of lithium to moles of tungsten (Li / W) of the positive electrode active material according to the present invention is 30 to 45, the surface of the positive electrode active material, which contains a crystalline phase mixed with at least one selected from the group consisting of Li2WO4, Li6WO6, Li7WO6, Li6W2O9, and Li5W2O9, has a high ratio of Li6WO6, Li6W2O9, and Li5W2O9 crystalline phases. Since the determining phase allows for the insertion and removal of Li, it is effective in improving the battery capacity, and since the mobility of Li is high, it is effective in improving resistance. Furthermore, the morphology of the positive electrode active material is maintained during the insertion and removal of Li, ensuring structural stability.

[0058] The number of moles of lithium can be 150 mmol / kg to 250 mmol / kg, specifically 160 mmol / kg to 230 mmol / kg, and more specifically 170 mmol / kg to 200 mmol / kg. The number of moles of tungsten can be 3 mmol / kg to 9 mmol / kg, specifically 3 mmol / kg to 8 mmol / kg, and more specifically 4 mmol / kg to 7 mmol / kg.

[0059] Specifically, the tungsten-containing coating layer may include a crystalline phase comprising at least one selected from the group consisting of Li2WO4, Li6WO6, Li7WO6, Li6W2O9, and Li5W2O9. In particular, the tungsten-containing coating layer may include at least one selected from the group consisting of Li2WO4, Li7WO6, and Li5W2O9 or Li6WO6, Li6W2O9, and Li5W2O9. In particular, when the positive electrode active material according to the present invention has the Li6WO6, Li6W2O9, and Li5W2O9 crystalline phase, Li can be inserted and removed, which is effective in improving the battery capacity, and the high mobility of Li is effective in improving resistance. Furthermore, the morphology of the positive electrode active material is maintained during the Li insertion and removal process, ensuring structural stability. Therefore, on the surface of a positive electrode active material where a crystalline phase containing at least one selected from the group consisting of Li2WO4, Li6WO6, Li7WO6, Li6W2O9, and Li5W2O9 is present, the higher the ratio of Li6WO6, Li6W2O9, and Li5W2O9 crystalline phases, the better the performance and structural stability of the battery can be.

[0060] The tungsten-containing coating layer may contain tungsten in an amount of 1,000 ppm to 4,000 ppm relative to the total weight of the positive electrode active material. Specifically, the tungsten may be present in an amount of 1,500 ppm to 4,000 ppm, more specifically 2,500 ppm to 3,500 ppm, relative to the total weight of the positive electrode active material. When the tungsten content satisfies the above numerical range, it reacts with residual lithium on the surface of the positive electrode active material to form Li x W y O z By controlling the appropriate amount of coating and crystal structure that can form a crystalline phase and react with residual lithium, it is possible to achieve improvements in battery capacity and resistance.

[0061] The tungsten-containing coating layer may further contain not only tungsten (W) but also one or more coating elements selected from the group consisting of Al, Ti, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S. Specifically, the tungsten-containing coating layer may further contain one or more coating elements selected from the group consisting of W, Al, Ti, Co, Mg, and Zr, and more specifically, it may contain W and Al. Here, if the tungsten-containing coating layer further contains the element boron (B), since boron (B) is more reactive with Li than tungsten (W), there is a problem in that the formation of crystalline phases such as Li6WO6, Li6W2O9, and Li5W2O9 is suppressed. Therefore, it is preferable that the tungsten-containing coating layer does not contain boron (B).

[0062] Specifically, when the positive electrode active material according to the present invention contains W and Al as a coating layer, the number of moles of aluminum measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) after pretreatment by immersing the positive electrode active material in deionized water at 25°C for 1 hour can be 1000 mmol / kg to 3000 mmol / kg, more specifically 1500 mmol / kg to 3000 mmol / kg, and more specifically 2000 mmol / kg to 2500 mmol / kg.

[0063] On the other hand, the positive electrode active material according to the present invention has a BET specific surface area of ​​0.50 m². 2 / g~1.20m 2 / g, specifically 0.80m 2 / g~0.90m 2 / g or 0.81m 2 / g ~ 0.87 m² / g, more specifically 0.82 m 2 / g~0.86m 2 It can be / g. The BET specific surface area of ​​the positive electrode active material is 0.50 m².2 If the value is less than / g, there is a risk of decreased dispersibility and capacity of the positive electrode active material itself, and the BET specific surface area is 1.20m². 2 If the value exceeds / g, there is a risk of reduced dispersibility of the positive electrode active material within the active material layer and increased resistance within the electrode due to aggregation of the positive electrode active material. Therefore, when the BET specific surface area satisfies the aforementioned numerical range, excellent initial efficiency and rate characteristics can be achieved.

[0064] On the other hand, the positive electrode active material according to the present invention is D 50 However, it can be 3.0 μm to 6.0 μm, specifically 3.0 μm to 5.5 μm, and more specifically 3.0 μm to 4.5 μm. D of the positive electrode active material 50 If the thickness is less than 3.0 μm, it becomes difficult to form the active material layer during electrode manufacturing, the electrolyte impregnation deteriorates, and the electrochemical properties decrease. 50 If the value exceeds 6.0 μm, lithium mobility decreases, resistance increases, and output characteristics deteriorate.

[0065] Method for manufacturing positive electrode active material Next, a method for producing a positive electrode active material according to the present invention will be described.

[0066] The present invention relates to a method for producing a positive electrode active material, comprising the steps of mixing a lithium composite transition metal oxide in a pseudo-single particle form, which is a single particle consisting of one nodule or a composite of 40 or fewer nodules, and in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, with a tungsten-containing raw material, and heat-treating the mixture at a temperature of 410°C to 490°C to form a tungsten-containing coating layer on the surface of the lithium composite transition metal oxide, and pre-treating the positive electrode active material by immersing it in deionized water at 25°C for 1 hour, and then analyzing it by inductively coupled plasma optical emission spectroscopy (ICP-OES) to determine that the ratio of moles of lithium to moles of tungsten (Li / W) is 30 to 45.

[0067] (1) Preparation step of lithium complex transition metal oxide First, the lithium composite transition metal oxide is formed by mixing a transition metal precursor and a lithium raw material and firing it, and the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, and it has a pseudo-single particle form consisting of a single nodule or a composite of 40 or fewer nodules.

[0068] The transition metal precursor can be produced by introducing a transition metal solution, an ammonium cation complex-forming agent, and a basic compound into a reactor and carrying out a coprecipitation reaction while stirring.

[0069] The transition metal solution can be produced by dissolving a transition metal-containing raw material in a solvent such as water. For example, it can be produced by dissolving a nickel-containing raw material or a cobalt-containing raw material in water. Furthermore, if necessary, the transition metal solution can be M 1 Contains raw materials and / or M 2 It may contain further raw material substances.

[0070] The transition metal-containing raw material can be an acetate, carbonate, nitrate, sulfate, halite, sulfide, or oxide of the transition metal.

[0071] Specifically, the nickel-containing raw material can be nickel-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and is not limited to, but may be Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, fatty acid nickel salt, nickel halide, or a combination thereof.

[0072] The cobalt-containing raw material can be cobalt-containing acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically can be, but is not limited to, Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, Co(SO4)2·7H2O, or combinations thereof.

[0073] Said M 1 The included raw materials may be manganese-containing raw materials and / or aluminum-containing raw materials. The manganese-containing raw materials may be, for example, Mn2O3, MnO2, Mn3O4, MnCO3, Mn(NO3)2, MnSO4·H2O, manganese acetate, manganese halides, or combinations thereof, and the aluminum-containing raw materials may be, for example, Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3 aluminum halides, or combinations thereof. However, in the case of Al, it may not be added to the transition metal aqueous solution but may be added together with the lithium raw material in the calcination step described later.

[0074] M 2 The raw materials contained are M 2 These can be acetates, carbonates, nitrates, sulfates, halites, sulfides, or oxides.

[0075] The amount of each transition metal-containing raw material to be added can be determined by considering the molar ratio of the transition metal in the cathode active material to be ultimately produced. In this invention, nickel-containing raw materials can be added in an amount of 50 mol% to 80 mol% relative to the total number of moles of transition metal-containing raw materials.

[0076] The ammonium cation complex-forming agent can be at least one selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3, and the compound can be introduced into the reactor in solution form dissolved in a solvent. Here, the solvent can be water, or a mixture of water and an organic solvent that can be homogeneously mixed with water (specifically, an alcohol, etc.).

[0077] Furthermore, the basic compound can be at least one selected from the group consisting of NaOH, KOH, and Ca(OH)2, and the compound can be introduced into the reactor in the form of a solution dissolved in a solvent. Here, the solvent can be water, or a mixture of water and an organic solvent that can be homogeneously mixed with water (specifically, an alcohol, etc.).

[0078] As described above, when the transition metal solution, ammonium cation complex forming agent, and basic compound are added to the reactor and stirred, the transition metal in the transition metal solution coprecipitates, generating transition metal precursor particles.

[0079] Once transition metal precursor particles are formed by the method described above, the particles are separated from the reaction solution to obtain the transition metal precursor. For example, the reaction solution can be filtered to separate the transition metal precursor, and then the separated transition metal precursor can be washed with water and dried to obtain the transition metal precursor. Here, if necessary, steps such as grinding and / or classification may be performed.

[0080] Next, the transition metal precursor and the lithium raw material are mixed and then calcined to produce lithium nickel oxide in single-particle or pseudo-single-particle form. Here, if necessary, M 1 Contains raw materials and / or M 2 The raw materials can be mixed together and fired, M 1 Contains raw materials and / or M 2 Specific examples of the raw materials contained are as described above.

[0081] As the lithium raw material, lithium-containing sulfates, nitrates, acetates, carbonates, oxalates, citrates, halides, hydroxides, or oxyhydroxides can be used. For example, Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, or Li3C6H5O7 or mixtures thereof can be used.

[0082] On the other hand, the lithium raw material and the positive electrode active material precursor can be mixed such that the molar ratio of Li to all metals in the precursor is 1:1 to 1.1:1, specifically 1.02:1 to 1.04:1. When the mixing ratio of the lithium raw material and the metals in the positive electrode active material precursor satisfies the above range, the layered crystal structure of the positive electrode active material develops well, and a positive electrode active material with excellent capacity characteristics and structural stability can be produced.

[0083] On the other hand, the firing is carried out at a temperature and time that can form a single particle consisting of one nodule or a pseudo-single particle form which is a composite of 40 or fewer nodules. In order to form a single particle or pseudo-single particle, firing must be carried out at a higher temperature than conventionally used when manufacturing lithium nickel oxide in secondary particle form. For example, if the composition of the precursor is the same, firing must be carried out at a temperature about 30°C to 100°C higher than conventionally used when manufacturing lithium nickel oxide in secondary particle form. The firing temperature for forming a single particle or pseudo-single particle may vary depending on the metal composition in the precursor.

[0084] The aforementioned firing can be carried out at 600°C to 1200°C, specifically at 800°C to 1000°C. When the firing temperature falls within this range, lithium composite transition metal oxides in single-particle or pseudo-single-particle form with excellent electrochemical properties can be produced. If the firing temperature is below 600°C, a positive electrode active material in secondary particle form is produced, and if it exceeds 1200°C, the firing is excessive, resulting in a decrease in electrochemical properties.

[0085] The aforementioned firing can be carried out in an oxygen atmosphere for 5 to 30 hours, specifically 8 to 20 hours. In this specification, an oxygen atmosphere refers to any atmosphere containing a sufficient amount of oxygen for firing, including an atmospheric atmosphere. It is particularly preferable to carry out the firing in an atmosphere where the partial pressure of oxygen is higher than that of the atmospheric atmosphere.

[0086] The lithium composite transition metal oxide produced by the calcination described above has a single particle form consisting of one single nodule or a pseudo-single particle form consisting of 40 or fewer nodules, specifically 2 to 30, and more specifically 2 to 20.

[0087] Furthermore, the lithium composite transition metal oxide may have a composition in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, specifically 50 mol% to 75 mol%, more specifically 55 mol% to 75 mol%, or 55 mol% to 70 mol%, and more specifically, it may be a lithium composite transition metal oxide in which the nickel content of the total metals other than lithium is 50 mol% to 80 mol%, specifically 50 mol% to 75 mol%, more specifically 55 mol% to 75 mol%, or 55 mol% to 70 mol%.

[0088] (2) Step of forming a tungsten-containing coating layer Next, the lithium composite transition metal oxide is mixed with a tungsten-containing raw material, and then coated by heat treatment to form a positive electrode active material including a tungsten-containing coating layer on the surface of the lithium composite transition metal oxide.

[0089] The lithium composite transition metal oxide can be mixed with a tungsten-containing raw material. The tungsten-containing raw material is WO3, Li3WO4 and (NH4) 10 W 12 O 41 It can be one or more elements selected from the group consisting of 5H2O, specifically WO3, but is not limited to this.

[0090] Furthermore, the tungsten-containing raw material can be mixed in an amount such that it is 1,000 ppm to 6,000 ppm, specifically 2,000 ppm to 5,000 ppm, or more specifically 2,000 ppm to 4,000 ppm, relative to the total weight of the positive electrode active material. When the mixing ratio of the tungsten-containing raw material satisfies the above range, a tungsten-containing coating layer can be uniformly formed on the surface of the lithium composite transition metal oxide, generating Li6WO6, Li6W2O9, and Li5W2O9 crystalline phases, enabling the insertion and removal of Li, and improving the battery's capacity and resistance.

[0091] The heat treatment can be carried out at a temperature of 410°C to 490°C, specifically 410°C to 460°C. If the heat treatment is carried out at a temperature below 410°C, the solid-phase reaction between the lithium composite transition metal oxide and WO3 does not proceed sufficiently at the low temperature, and WO3 remains separated, resulting in a problem where the number of moles of lithium is low and the number of moles of tungsten is high. If the heat treatment is carried out at a temperature above 490°C, lithium volatilizes, and the number of moles measured decreases, but tungsten does not volatilize and remains, resulting in a problem where there is an imbalance in the number of moles of lithium and tungsten.

[0092] The heat treatment can be carried out for 3 to 7 hours, specifically 4 to 6 hours. When the heat treatment is carried out for the aforementioned time, the reaction between the lithium composite transition metal oxide and Al2O3 and WO3 is sufficiently carried out, forming a uniform coating layer, and the reaction can generate a high proportion of crystalline phases that undergo redox reactions, such as Li6WO6, Li6W2O9, and Li5W2O9.

[0093] Furthermore, when mixing the lithium composite transition metal oxide and the tungsten-containing raw material, an aluminum raw material can be further mixed in. The aluminum raw material can be one or more selected from the group consisting of Al2O3, Al(OH)3, Al(NO3)3, Al2(SO4)3, (HO)2AlCH3CO2, HOAl(CH3CO2)2, Al(CH3CO2)3, and aluminum halides. Specifically, it can be Al2O3, but is not limited to this.

[0094] Furthermore, the aluminum-containing raw material can be mixed in an amount such that it is 400 ppm to 3000 ppm, specifically 800 ppm to 2500 ppm, or more specifically 800 ppm to 2000 ppm, relative to the total weight of the positive electrode active material. When the mixing ratio of the aluminum-containing raw material satisfies the above range, a protective layer is formed on the surface of the electrode, reducing the interfacial resistance between the electrode and the electrolyte, thereby improving the mobility of Li and thus improving the charging and discharging speeds.

[0095] positive electrode The positive electrode according to the present invention includes the positive electrode active material of the present invention as described above. Specifically, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer includes the positive electrode active material according to the present invention. Since the positive electrode active material has been described above, a detailed explanation will be omitted, and only the remaining components will be described in detail below.

[0096] The positive electrode current collector is not particularly limited as long as it contains a highly conductive metal, allows for easy adhesion of the positive electrode active material layer, and is unreactive within the battery voltage range. Examples of materials that can be used for the positive electrode current collector include stainless steel, aluminum, nickel, titanium, heat-treated carbon, or aluminum or stainless steel with surface treatments such as carbon, nickel, titanium, or silver. Furthermore, the positive electrode current collector can typically have a thickness of 3 μm to 500 μm, and fine irregularities can be formed on its surface to enhance the adhesion of the positive electrode active material. It can be used in various forms, such as films, sheets, foils, meshes, porous materials, foams, and nonwoven fabrics.

[0097] The positive electrode active material layer may, as necessary, selectively include a conductive material and a binder together with the positive electrode active material.

[0098] Here, the positive electrode active material may be included in an amount of 80% to 99% by weight, more specifically, 90% to 98% by weight, relative to the total weight of the positive electrode active material layer.

[0099] The conductive material is used to impart conductivity to the electrodes and can be used without particular limitations in a battery that does not cause chemical changes and has electronic conductivity. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. Of these, one or more can be used. The conductive material can be included in the total weight of the positive electrode active material layer in an amount of 0.01% to 10% by weight, specifically 0.1% to 9% by weight, and more specifically 0.1% to 5% by weight.

[0100] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which the hydrogen atoms of these materials are substituted with Li, Na, or Ca, or various copolymers thereof. One of these materials alone or a mixture of two or more materials can be used. The binder may be present in an amount of 1% to 30% by weight, specifically 1% to 20% by weight, or more specifically, 1% to 10% by weight, relative to the total weight of the positive electrode active material layer.

[0101] The positive electrode can be manufactured by a conventional method for manufacturing a positive electrode, except that the positive electrode active material is used. Specifically, it can be manufactured by applying a positive electrode slurry composition, prepared by dissolving or dispersing the positive electrode active material and, if necessary, selectively, a binder, a conductive material, and a dispersant in a solvent, onto a positive electrode current collector, followed by drying and rolling.

[0102] The solvent can be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water. One of these can be used alone or a mixture of two or more. The amount of solvent used should be sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, taking into account the slurry coating thickness and manufacturing yield, and to have a viscosity that allows for excellent thickness uniformity during subsequent coating for the manufacture of the positive electrode.

[0103] Alternatively, the positive electrode can also be manufactured by casting the positive electrode slurry composition onto another support, peeling it off the support, and then laminating the resulting film onto the positive electrode current collector.

[0104] Lithium-ion rechargeable battery Next, the lithium secondary battery according to the present invention will be described.

[0105] The lithium secondary battery specifically includes a positive electrode, a negative electrode located opposite the positive electrode, and a separator and electrolyte interposed between the positive and negative electrodes. As the positive electrode is as described above, a detailed explanation will be omitted, and only the remaining components will be described in detail below.

[0106] Furthermore, the lithium secondary battery may selectively further include a battery container for housing the electrode assembly comprising the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0107] In the lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0108] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy can be used. The negative electrode current collector can usually have a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, fine irregularities can be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0109] The negative electrode active material layer may selectively include a binder and a conductive material together with the negative electrode active material.

[0110] As the negative electrode active material, compounds capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. βExamples include metallic oxides that can be doped and dedoped with lithium, such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more mixtures thereof can be used. A metallic lithium thin film can also be used as the negative electrode active material. Furthermore, both low-crystallinity carbon and high-crystallinity carbon can be used as the carbon material. Typical examples of low-crystalline carbon include soft carbon and hard carbon, while typical examples of high-crystalline carbon include amorphous, plate-like, flaky, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch-derived cokes, which are high-temperature heat-treated carbons.

[0111] The negative electrode active material may be present in an amount of 80% to 99% by weight, 82% to 99% by weight, or 84% to 99% by weight, relative to the total weight of the negative electrode active material layer.

[0112] The binder is a component that helps to bond the conductive material, active material, and current collector, and is usually added in an amount of 0.1% to 10% by weight relative to the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0113] The conductive material is a component for further improving the conductivity of the negative electrode active material and can be included in an amount of 1% to 30% by weight, 1% to 20% by weight, or 1% to 10% by weight relative to the total weight of the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and examples of such materials that can be used include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0114] The negative electrode active material layer can be manufactured by coating a negative electrode slurry composition, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and then drying it, or by casting the negative electrode slurry composition onto another support, peeling it off this support, and then laminating the resulting film onto the negative electrode current collector.

[0115] On the other hand, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Generally, any separator commonly used in lithium secondary batteries can be used without particular limitations, but those with low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity are particularly preferred. Specifically, porous polymer films, such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers, or laminated structures of two or more layers thereof, can be used. Ordinary porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. Furthermore, coated separators containing ceramic components or polymer materials can be used to ensure heat resistance or mechanical strength, and can be selectively used as single-layer or multi-layer structures.

[0116] Furthermore, the electrolytes used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0117] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0118] The aforementioned organic solvent can be used without particular limitations, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the aforementioned organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and can include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0119] The lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions for use in lithium secondary batteries. Specifically, the anion of the lithium salt is F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - CF3CF2SO3 - (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - , (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - The lithium salt can be selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably in the range of 0.1M to 4.0M, more specifically 0.5M to 3.0M, and more specifically 1.0M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte can exhibit excellent electrolyte performance due to having appropriate conductivity and viscosity, and lithium ions can move effectively.

[0120] In addition to the components of the electrolyte, the electrolyte may also contain one or more additives for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphite, triethyl alcoholamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethyl alcohol, or aluminum trichloride. Here, the additive may be present in an amount of 0.1% to 10.0% by weight relative to the total weight of the electrolyte.

[0121] As described above, the lithium secondary battery according to the present invention has excellent stability and electrochemical performance even at high voltages, allowing the charge termination voltage to be 4.35V or higher during operation. Thus, when operated at high voltages, it can achieve superior high-capacity characteristics compared to conventional lithium secondary batteries.

[0122] Furthermore, the lithium secondary battery according to the present invention exhibits excellent discharge capacity, output characteristics, and capacity retention rate stably, making it useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0123] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0124] The aforementioned battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0125] Hereinafter, embodiments of the present invention will be described in detail so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein.

[0126] Examples and Comparative Examples Example 1 A transition metal precursor with a Ni:Co:Mn molar ratio of 0.6:0.1:0.3 and a lithium raw material (LiOH) are mixed so that the transition metal (Ni+Co+Mn):Li molar ratio is 1:1.03. After mixing, the mixture is calcined at 950°C for 14 hours to produce single-particle LiNi. 0.6 Co 0.1 Mn 0.3 O2 was produced.

[0127] Next, the calcined material was mixed with Al2O3 and WO3 so that the molar ratio of the calcined material:Al:W was 100:0.5:0.15, and then heat-treated at 425°C for 5 hours to produce a single-particle positive electrode active material powder with an aluminum and tungsten-containing coating layer.

[0128] Example 2 The positive electrode active material powder was produced in the same manner as in Example 1, except that the mixture was heat-treated at 450°C for 5 hours.

[0129] Comparative Example 1 The positive electrode active material powder was produced in the same manner as in Example 1, except that the mixture was heat-treated at 400°C for 5 hours.

[0130] Comparative Example 2 The positive electrode active material powder was produced in the same manner as in Example 1, except that the mixture was heat-treated at 500°C for 5 hours.

[0131] Comparative Example 3 The positive electrode active material powder was produced in the same manner as in Example 1, except that the calcined material was mixed with Al2(OH)3 and WO3.

[0132] Comparative Example 4 The positive electrode active material powder was produced in the same manner as in Example 1, except that the calcined material was mixed with Al2O3, WO3, and H3O3 so that the molar ratio of Al:W:B was 100:0.5:0.15:0.15.

[0133] Experimental Example 1: ICP Analysis of Cathode Active Material The number of moles of Li and W elements on the surface of the positive electrode active materials produced in Examples 1-2 and Comparative Examples 1-4 was measured.

[0134] Each cathode active material was immersed in deionized water at 25°C for 1 hour, filtered, and the filtrate was analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-OES (PerkinElmer, Optima7300DV)) to measure the number of moles of Li and W elements in the cathode active material.

[0135] The measurement results are shown in [Table 1] below.

[0136] [Table 1]

[0137] Experimental Example 2: Measurement of the BET specific surface area of ​​the positive electrode active material For the cathode active materials prepared in Examples 1-2 and Comparative Examples 1-4, the amount of nitrogen gas adsorbed at liquid nitrogen temperature (77K) was calculated using a specific surface area analyzer (BELSORP-mino II, manufactured by BEL Japan). The results are shown in Table 2 below.

[0138] [Table 2]

[0139] Experimental Example 3: Evaluation of Initial Efficiency The initial efficiency of lithium secondary battery half-cells manufactured using the positive electrode active materials produced in Examples 1-2 and Comparative Examples 1-4, respectively, was evaluated as described below.

[0140] <Manufacturing of lithium-ion secondary batteries> The positive electrode active material, conductive material (carbon black), and PVDF binder prepared in Examples 1-2 and Comparative Examples 1-4 were mixed in N-methylpyrrolidone in a weight ratio of 95:2:3 to produce a positive electrode slurry. The positive electrode slurry was applied to one surface of an aluminum current collector, dried at 60°C, and then rolled to produce a positive electrode.

[0141] The negative electrode was manufactured using lithium metal, with a separator interposed between the positive electrode and the negative electrode manufactured by the method described above to produce an electrode assembly. This assembly was then placed inside a battery case, and an electrolyte was injected into the case to produce a battery cell. The electrolyte was prepared by dissolving 0.6 M LiPF6 in a mixed organic solvent of ethylene carbonate (EC):dimethyl carbonate (DMC):ethyl methyl carbonate (EMC) in a volume ratio of 1:2:1, and adding 2% by weight of vinylene carbonate (VC).

[0142] Specifically, after the manufactured half-cells were activated (formated), they were each charged at 25°C with a constant current of 0.1C until the voltage reached 4.4V, and then discharged with a constant current of 0.1C until the voltage reached 2.5V. The initial charge capacity, initial discharge, capacity value, and the ratio of initial discharge capacity to initial charge capacity were defined as the initial efficiency and are shown in [Table 3] below.

[0143] [Table 3]

[0144] Referring to [Table 3] above, it can be confirmed that the initial charge / discharge capacity and efficiency of lithium secondary batteries containing the positive electrode active materials of Examples 1-2 are superior to those of Comparative Examples 1-4.

[0145] Experimental Example 4: Evaluation of Rate Characteristics The lithium secondary battery half-cells that had been charged and discharged once in Experimental Example 3 were charged / discharged under the same conditions as in [Table 4], and their rate characteristics were evaluated. The results are shown in [Table 4] below.

[0146] [Table 4]

[0147] Referring to [Table 4] above, it can be confirmed that the rate characteristics of the lithium secondary batteries containing the positive electrode active materials of Examples 1-2 are superior to those of Comparative Examples 1-4.

Claims

1. A lithium composite transition metal oxide in a pseudo-single particle form, consisting of a single particle made up of one nodule or a composite of 40 or fewer nodules, wherein the nickel content of the total metal excluding lithium is 50 mol% to 80 mol%, A positive electrode active material comprising a tungsten-containing coating layer formed on the surface of the lithium composite transition metal oxide, The positive electrode active material is pretreated by immersing it in deionized water at 25°C for 1 hour, and then measured by inductively coupled plasma spectroscopy (ICP-OES) to obtain a ratio of 30 to 45 moles of lithium to moles of tungsten (Li / W).

2. The tungsten-containing coating layer contains Li ２ WO ４ Li ６ WO ６ Li ７ WO ６ Li ６ W ２ O ９ and Li ５ W ２ O ９ The positive electrode active material according to claim 1, comprising a crystal phase containing at least one selected from the group consisting of

3. The positive electrode active material according to claim 1, wherein the number of moles of lithium is 150 mmol / kg to 250 mmol / kg.

4. The positive electrode active material according to claim 1, wherein the number of moles of tungsten is 3 mmol / kg to 9 mmol / kg.

5. The lithium composite transition metal oxide has the composition represented by the following chemical formula 1, [Chemical formula 1] Li ａ Ni ｂ Co ｃ M １ ｄ M ２ ｅ O ２ In the above chemical formula 1, M １ is at least one selected from the group consisting of Mn and Al, ２ The positive electrode active material according to claim 1, wherein is at least one selected from the group consisting of Ti, Mg, Zr, Y, Ba, Ca, Zr, Sr, W, Ta, Nb, and Mo, and satisfies 1.0 ≤ a ≤ 1.5, 0.5 ≤ b ≤ 0.8, 0 < c ≤ 0.3, 0 < d ≤ 0.3, and 0 ≤ e ≤ 0.

2.

6. The BET specific surface area of ​​the positive electrode active material is 0.50 m². ２ / g to 1.20m ２ The positive electrode active material according to claim 1, wherein the value is / g.

7. D of the positive electrode active material ５０ The positive electrode active material according to claim 1, wherein the particle size is 3.0 μm to 6.0 μm.

8. The tungsten-containing coating layer further contains aluminum, The positive electrode active material according to claim 1, wherein the positive electrode active material is pretreated by immersing it in deionized water at 25°C for 1 hour, and then analyzed by inductively coupled plasma spectroscopy (ICP-OES) to determine that the number of moles of aluminum is 3 mmol / kg to 10 mmol / kg.

9. The positive electrode active material according to claim 1, wherein the tungsten-containing coating layer further comprises one or more coating elements selected from the group consisting of Al, Ti, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, and S.

10. A method for producing a positive electrode active material, comprising the steps of mixing a lithium composite transition metal oxide in a pseudo-single particle form, which is a single particle consisting of one nodule or a composite of 40 or fewer nodules, and in which the nickel content of the total metals excluding lithium is 50 mol% to 80 mol%, with a tungsten-containing raw material, and heat-treating the mixture at a temperature of 410°C to 490°C to form a tungsten-containing coating layer on the surface of the lithium composite transition metal oxide, wherein the nickel content of the total metals excluding lithium is 50 mol% to 80 mol%, the mixture contains a single particle consisting of one nodule or a composite of 40 or fewer nodules, and the mixture contains a tungsten-containing raw material, and heat-treats the mixture at a temperature of 410°C to 490°C to form a tungsten-containing coating layer on the surface of the lithium composite transition metal oxide, A method for producing a positive electrode active material, wherein the positive electrode active material is pretreated by immersing it in deionized water at 25°C for 1 hour, and then the ratio of moles of lithium to moles of tungsten (Li / W), measured by inductively coupled plasma spectroscopy (ICP-OES), is 30 to 45.

11. The tungsten-containing raw material is WO ３ Li ３ WO ４ and (NH ４ ) １０ W １２ O ４１ ・5H ２ A method for producing a positive electrode active material according to claim 10, wherein the active material is one or more selected from the group consisting of O.

12. The method for producing a positive electrode active material according to claim 10, wherein the tungsten-containing raw material is mixed in an amount of 1,000 ppm to 6,000 ppm relative to the total weight of the positive electrode active material.

13. The method for producing a positive electrode active material according to claim 10, wherein the heat treatment is performed for 3 to 7 hours.

14. The method for producing the positive electrode active material according to claim 10, further comprising the step of mixing aluminum raw materials.

15. The aforementioned aluminum raw material is Al ２ O ３ Al(OH) ３ , Al (NO ３ ) ３ Al ２ (SO ４ ) ３ (HO) ２ AlCH ３ CO ２ , HOAl(CH ３ CO ２ ) ２ Al(CH) ３ CO ２ ) ３ A method for producing a positive electrode active material according to claim 14, wherein the active material is one or more selected from the group consisting of and aluminum halides.

16. The method for producing a positive electrode active material according to claim 14, wherein the aluminum-containing raw material is mixed in an amount of 400 ppm to 3000 ppm relative to the total weight of the positive electrode active material.

17. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 9.

18. A lithium secondary battery comprising the positive electrode described in claim 17.

19. The lithium secondary battery according to claim 18, wherein the lithium secondary battery has a charge termination voltage of 4.35V or higher when in operation.

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