High-performance positive electrode active material for lithium secondary battery with exclusion of use of transition metal precursor, preparation method therefor, and lithium secondary battery using same

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, a preparation method therefor, and a lithium secondary battery comprising same, wherein the positive electrode active material comprises a lithium-containing compound in a single crystal form, which has an average particle size of 1 ㎛ to 5 ㎛ and is formed of: a first raw material including a lithium-containing raw material; and a second raw material including at least one selected from the group consisting of nickel-containing raw materials, cobalt-containing raw materials, manganese-containing raw materials, iron-containing raw materials, and aluminum-containing raw materials.

Description

A high-performance cathode active material for a lithium secondary battery that excludes the use of a transition metal precursor, a method for producing the same, and a lithium secondary battery using the same

[0001] The present invention relates to a cathode active material for a high-performance lithium secondary battery that excludes the use of a transition metal precursor, a method for producing the same, and a lithium secondary battery using the same.

[0002] Lithium secondary batteries are the most promising energy device in the IT, electric vehicle (EV), and energy storage systems (ESS). Since Sony first commercialized them in 1990, lithium secondary batteries have undergone remarkable development over the past 30 years. While initially limited to mobile applications such as cell phones and laptops, their applications have expanded beyond electric vehicles to include large-scale energy storage devices, demonstrating continued advancement. In particular, with the rise of environmental friendliness and efficiency, the electric vehicle and energy storage sectors have become new business areas, rapidly expanding the application areas of lithium secondary batteries. While lithium secondary batteries, initially applied to the IT sector, were initially applicable only if they met lifespan and capacity targets, their expansion into the electric vehicle and energy storage sectors has led to a growing demand for improved performance. In these fields, lithium secondary batteries must meet not only capacity and lifespan targets but also stringent safety, reliability, and, above all, price.

[0003] Accordingly, there is a need for the development of positive electrode active materials for lithium secondary batteries that can be applied to various fields, including not only the IT field but also battery vehicles and energy storage devices.

[0004] [Prior Art Literature]

[0005] [Patent Document]

[0006] Korean Patent Publication No. 10-1871919 (June 21, 2018)

[0007] The present invention excludes the use of a transition metal precursor generally used in conventional methods for producing a positive electrode active material for a lithium secondary battery and adopts a novel process, and provides a method for producing a positive electrode active material for a lithium secondary battery, including the steps of: (a) preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material; (b) preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed; (c) drying the nano slurry to produce nanoparticles; and (d) calcining the dried nanoparticles to produce a lithium-containing compound in the form of a single crystal having an average particle size of 1 μm to 5 μm.

[0008] However, the technical problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0009] The present invention provides a method for producing a positive electrode active material for a lithium secondary battery, comprising the steps of: (a) preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material; (b) preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed; (c) drying the nano slurry to produce nanoparticles; and (d) calcining the dried nanoparticles to produce a lithium-containing compound in a single crystal shape having an average particle size of 1 μm to 5 μm.

[0010] In the above step (a), the second raw material may be in the form of an oxide or a hydroxide.

[0011] In the above step (a), i) when the second raw material includes both a nickel-containing raw material and a manganese-containing raw material, it may additionally include one or more doping metal oxides selected from the group consisting of Al2O3, TiO2, ZrO2, MoO6, and Ta2O5, or ii) when the second raw material includes an iron-containing raw material, it may additionally include a PO4-containing raw material.

[0012] ⅱ) After dry mixing the second raw material including the iron-containing raw material and the PO4-containing raw material, a step of first preliminary firing at a temperature of 150°C to 200°C and then second preliminary firing at a temperature of 450°C to 800°C may be added.

[0013] In the above step (b), the volume ratio of the raw materials and the solvent in the solution may be 1:1 to 1:5.

[0014] In the above step (b), wet nanomilling can be performed at a speed of 1,000 rpm to 5,000 rpm for 1 to 5 hours.

[0015] In the particle distribution of the nano slurry in the above step (b), 0.1 ㎛ ≤ D50 ≤ 0.5 ㎛ and Dmax < 1 ㎛ may be.

[0016] In the above step (c), drying can be performed through mechanical drying in a planetary dispersive mixer.

[0017] A jacket having a circulation path formed on the outer surface of the planetary dispersive mixer through which a heating fluid circulates is additionally provided, and the heating fluid can maintain a temperature of 50°C to 200°C.

[0018] In the above step (c), drying can be performed under vacuum conditions.

[0019] In the above step (d), the firing can be performed at a temperature of 600°C to 1000°C for 5 to 20 hours.

[0020] After the above step (d), a step of forming a surface treatment layer including Al(OH)3, a boron-containing compound, and a silicon-containing compound on the lithium-containing compound in the form of a single crystal may be added.

[0021] In one embodiment of the present invention, a cathode active material for a lithium secondary battery is provided, which comprises a lithium-containing compound in a single crystal shape, formed from a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material, and has an average particle size of 1 ㎛ to 5 ㎛.

[0022] A bimodal shape can be realized by additionally mixing nanoparticles having an average particle size of 100 nm to 500 nm into the lithium-containing compound in the single crystal shape.

[0023] It may further include a surface treatment layer including Al(OH)3, a boron-containing compound, and a silicon-containing compound formed on the lithium-containing compound in the single crystal shape.

[0024] ⅰ) When the second raw material includes both a nickel-containing raw material and a manganese-containing raw material, it may additionally include one or more doping metal oxides selected from the group consisting of Al2O3, TiO2, ZrO2, MoO6, and Ta2O5, or ⅱ) When the second raw material includes an iron-containing raw material, it may additionally include a PO4-containing raw material.

[0025] In another embodiment of the present invention, a lithium secondary battery including the positive electrode active material is provided.

[0026] The method for manufacturing a cathode active material for a lithium secondary battery according to the present invention excludes the use of a transition metal precursor, and by wet nanomilling a solution in which each raw material (raw material in the form of an oxide or a form of a hydroxide) is dissolved and dispersed, and then drying (particularly, mechanical drying after being placed in a planetary dispersive mixer), a lithium-containing compound in the form of a single crystal having an average particle size of 1 ㎛ to 5 ㎛ can be easily manufactured with high efficiency. In some cases, by using raw materials obtained from lithium ion waste batteries through a wet process as each raw material, there is an advantage in that environmental problems, particularly water pollution problems, that arise during the manufacture of transition metal precursors can be solved.

[0027] The cathode active material for a lithium secondary battery manufactured according to the present invention has the advantage of stabilizing the crystal structure compared to a polycrystalline form by uniformly distributing lithium within a single crystal form. Accordingly, it has excellent structural stability under high-voltage charging conditions, thereby securing high-capacity characteristics of a lithium secondary battery, and also has excellent characteristics under high-temperature conditions, thereby securing high-temperature lifespan, recovery, and maintenance characteristics of a lithium secondary battery. In particular, it has excellent thermal stability compared to a polycrystalline form, thereby improving the stability of a lithium secondary battery.

[0028] That is, a lithium secondary battery using a high-performance and low-cost cathode active material manufactured according to the present invention has excellent performance advantages such as discharge capacity and efficiency, C-rate, and room temperature and high temperature life characteristics.

[0029] FIG. 1(a) is a schematic diagram showing a stirrer used for dissolution and dispersion in Example 1, FIG. 1(b) is a photograph showing a wet nano-mill facility used for wet nano-milling in Example 1, FIG. 1(c) is a graph showing the particle distribution of a nano slurry according to Example 1, and FIG. 1(d) is a photograph showing a planetary dispersive mixer used in Example 1.

[0030] Figures 2(a) and (b) are graphs comparing the C-rate and 0.1C capacity of coin cells according to Example 2 and Comparative Example 1, respectively.

[0031] Figure 3 is a graph comparing the 0.1C capacity of coin cells according to Example 3 and Comparative Example 2.

[0032] Fig. 4(a) is an SEM photograph comparing lithium-containing compounds according to Example 4 and Comparative Example 3, and Figs. 4(b) and (c) are graphs comparing 0.1C capacity and room temperature lifespan of coin cells according to Example 4 and Comparative Example 3, respectively.

[0033] FIG. 5(a) is a graph showing an XRD pattern of a lithium-containing compound according to Example 5, FIG. 5(b) is an SEM photograph comparing lithium-containing compounds according to Example 5 and Comparative Example 4, and FIG. 5(c) is a graph comparing 0.1C capacities of coin cells according to Example 5 and Comparative Example 3.

[0034] Figures 6(a) and (b) are graphs showing the 0.1C capacity and high-temperature lifespan, respectively, of a coin cell according to Example 6.

[0035] Fig. 7(a) is a SEM photograph comparing lithium-containing compounds according to Example 7, Fig. 7(b) is a graph comparing XRD patterns of lithium-containing compounds according to Example 7 at different sintering temperatures, and Figs. 7(c) to (e) are graphs comparing 0.1C capacity, high-temperature lifespan, and C-rate of coin cells according to Example 7 and Comparative Example 5, respectively.

[0036] Figure 8 is a graph comparing the 0.1C capacity of coin cells according to Example 8.

[0037] As with conventional methods for manufacturing positive electrode active materials for lithium secondary batteries, dry mixing of lithium-containing raw materials and transition metal precursors (optionally, doped metal oxides) followed by sintering results in insufficient uniform distribution of the raw materials, and the resulting particles inevitably form low-density polycrystalline structures. Consequently, the performance of lithium secondary batteries employing these methods has been limited.

[0038] The present inventors, while conducting research to exclude the use of transition metal precursors generally used in conventional methods for producing positive electrode active materials for lithium secondary batteries, confirmed that a lithium-containing compound in the form of a single crystal having an average particle size of 1 ㎛ to 5 ㎛ can be easily and efficiently produced by dissolving and dispersing each raw material (raw material in the form of oxide or hydroxide) in a solution, wet nanomilling the solution, and then placing it in a planetary dispersive mixer and drying it (in particular, mechanically drying it after placing it in a planetary dispersive mixer), thereby completing the present invention.

[0039] Hereinafter, the present invention will be described in detail.

[0040]

[0041] Method for manufacturing positive electrode active material for lithium secondary batteries

[0042] The present invention provides a method for producing a positive electrode active material for a lithium secondary battery, comprising the steps of: (a) preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material; (b) preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed; (c) drying the nano slurry to produce nanoparticles; and (d) calcining the dried nanoparticles to produce a lithium-containing compound in a single crystal shape having an average particle size of 1 μm to 5 μm.

[0043] First, the cathode active material for a lithium secondary battery according to the present invention includes a step [step (a)] of preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material.

[0044] The above first raw material includes a lithium-containing raw material, and for example, Li2CO3, LiOH, etc. can be used as the lithium-containing raw material.

[0045] Meanwhile, the second raw material includes at least one selected from the group consisting of nickel-containing raw materials, cobalt-containing raw materials, manganese-containing raw materials, iron-containing raw materials, and aluminum-containing raw materials, and may be in the form of an oxide or a hydroxide. For example, NiO, Ni(OH)2, etc. can be used as the nickel-containing raw material, Co3O4, Co(OH)2, etc. can be used as the cobalt-containing raw material, Mn3O4, Mn(OH)2, etc. can be used as the manganese-containing raw material, Fe2O3, etc. can be used as the iron-containing raw material, and Al2O3, etc. can be used as the aluminum-containing raw material. These may be commercialized products, or may be raw materials obtained through a wet process from lithium-ion waste batteries. In the case of raw materials obtained through a wet process from lithium-ion waste batteries, there is an advantage in that environmental problems occurring during the manufacture of transition metal precursors, particularly, water pollution problems, can be solved. Moreover, the second raw material may be Al2O3, TiO 2, ZrO2, MoO6 and Various known doping metal oxides such as Ta2O5 can be additionally added, and the total doping amount can be at the level of 1,000 ppm to 5,000 ppm.

[0046] In addition, the average particle size of the second raw material may be 100 nm to 10 ㎛, and is preferably 100 nm to 5 ㎛, but is not limited thereto. On the other hand, if the average particle size of the second raw material is too small, such as several hundred nm, when dry mixing and firing are performed, the final lithium-containing compound is also only several hundred nm in size (e.g., D50 = 100 to 500 nm), so there is a limitation in that the composite density is low when manufacturing the electrode plate. However, even if the average particle size of the second raw material is several hundred nm, when it is put into a wet nanomilling and planetary dispersive mixer, mechanically dried, and then fired, the average particle size of the final lithium-containing compound The size is 1~10 ㎛ (preferably 1~5 ㎛) Since it can be implemented in ㎛ size, it is possible to manufacture high-density electrode plates during electrode manufacturing, so there is an advantage in that it can be developed into a high-capacity lithium secondary battery.

[0047] In particular, i) when the second raw material contains both nickel-containing raw materials and manganese-containing raw materials, Al2O3, TiO 2, ZrO2, MoO6 and It may additionally include one or more doping metal oxides selected from the group consisting of Ta2O5, and each doping amount may be at a level of 500 ppm to 5,000 ppm.

[0048] In addition, ⅱ) when the second raw material includes an iron-containing raw material, a PO4-containing raw material may be additionally included. For example, (NH4)H2PO4, etc. may be used as the PO4-containing raw material. In some cases, a manganese-containing raw material may be further added.

[0049] A step of first pre-firing at a temperature of 150° C. to 200° C. and then second pre-firing at a temperature of 450° C. to 800° C. after dry mixing or wet mixing using a solvent such as ethanol, grinding and drying the second raw material including the iron-containing raw material, the PO4-containing raw material and optionally the manganese-containing raw material may be added. Preferably, first pre-firing is performed at a temperature of 160° C. to 180° C. for 5 to 20 hours (particularly, 15 to 18 hours) and then second pre-firing is performed at a temperature of 650° C. to 800° C. for 5 to 20 hours (particularly, 10 to 15 hours), thereby converting each raw material into single-phase single crystal FePO4 or Mn 1-x Fe x PO4(0.2≤x≤0.8) can be manufactured. The first preliminary calcination or the second preliminary calcination may be performed after the wet nanomilling of step (b) and the drying of step (c) described below. At this time, the manufactured FePO4 or Mn 1-x Fex Average particle size of PO4(0.2≤x≤0.8) The size is 1~10 ㎛ (preferably 1~5 ㎛) As it is implemented in ㎛ size, it has high-density characteristics and can be used to manufacture high-density electrode plates during electrode plate manufacturing, so it has the advantage of being able to be developed into a high-capacity lithium secondary battery.

[0050] Meanwhile, the conventionally used FP precursor is manufactured by a coprecipitation method using an acid-base neutralization reaction, and environmental pollutants are generated during the manufacturing process due to the generation of sulfuric acid and ammonia byproducts. Afterwards, it is purified through numerous washing processes, and the large amount of wastewater generated causes serious water pollution problems. Moreover, since the FP precursor manufactured in this way is several hundred nm in size, the final lithium-containing compound is also only several hundred nm in size (e.g., D50 = 100-500 nm), so the composite density is low when manufacturing the electrode plate, making it difficult to implement it as a high-capacity lithium secondary battery. Therefore, the FP precursor manufacturing process according to the present invention is a simple, low-cost, and pollution-free process, and has very strong competitiveness in terms of the performance improvement of the final lithium secondary battery and the eco-friendliness of the process.

[0051] Next, the cathode active material for a lithium secondary battery according to the present invention includes a step [step (b)] of preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed.

[0052] The first raw material and the second raw material are dissolved and dispersed to prepare a solution, and a stirrer may be used at this time. The volume ratio of the raw materials and the solvent in the solution may be 1:1 to 1:5, and is preferably 1:2 to 1:4, but is not limited thereto.

[0053] When dissolving and dispersing the first and second raw materials, a carbon source may be added to increase conductivity, if necessary. For example, polysaccharides such as glucose and sucrose may be used as the carbon source, and the amount added may be 1 wt% to 8 wt% of the total weight of the lithium-containing compound described below.

[0054] The above wet nanomilling can be performed at a speed of 1,000 rpm to 5,000 rpm for 1 to 5 hours, and is preferably performed at a speed of 2,000 rpm to 5,000 rpm for 2 to 5 hours, but is not limited thereto. At this time, a wet nano-mill facility can be used. In terms of the particle distribution of the nano slurry, it can be 0.1 ㎛ ≤ D50 ≤ 0.5 ㎛ (preferably, 0.1 ㎛ ≤ D50 ≤ 0.2 ㎛), and Dmax < 1 ㎛.

[0055] Next, the cathode active material for a lithium secondary battery according to the present invention includes a step [step (c)] of drying the nano slurry to produce nano particles.

[0056] The above drying can be performed through known drying methods such as mechanical drying, spray drying, etc. In particular, the drying can be performed through mechanical drying in a planetary dispersive mixer, and a jacket having a circulation path formed on the outer surface of the planetary dispersive mixer through which a heating fluid is circulated is additionally provided, and the heating fluid can maintain a temperature of 50°C to 200°C. In the case of employing spray drying or the like instead of mechanical drying, it is inevitable to manufacture low-density polycrystalline particles (spherical particles with an empty interior) formed by primary and secondary particles clumping together.

[0057] The planetary dispersive mixer is additionally provided with a jacket having a circulation path formed on the outer surface thereof through which a heating fluid circulates, and the heating fluid can maintain a temperature of 50°C to 200°C (preferably, a temperature of 80°C to 150°C). In addition, the mechanical drying can uniformly evaporate the melt by blowing air or dry nitrogen gas under vacuum conditions. Accordingly, it is possible to manufacture high-density single-crystal nanoparticles in which lithium is uniformly distributed.

[0058] Next, the positive electrode active material for a lithium secondary battery according to the present invention includes a step [step (d)] of producing a lithium-containing compound in the form of a single crystal having an average particle size of 1 ㎛ to 5 ㎛ by calcining the dried nanoparticles.

[0059] Through the above-described calcination, the dried nanoparticles can grow to produce a lithium-containing compound in the form of a single crystal with an average particle size of 1 μm to 5 μm. The above-described calcination can be performed at a temperature of 600°C to 1000°C for 5 to 20 hours.

[0060] The above lithium-containing compound may be a lithium-nickel-cobalt-manganese compound, a lithium-nickel-cobalt-manganese-aluminum compound, a lithium-nickel-iron-aluminum compound, a lithium-nickel-manganese compound, a lithium-iron-PO4 compound, or a lithium-manganese-iron-PO4 compound, and in some cases, Al2O3, TiO 2, ZrO2, MoO6 and Various known doping metal oxides such as Ta2O5 can be additionally added.

[0061] When the lithium-containing compound is a lithium-nickel-cobalt-manganese compound, a lithium-nickel-cobalt-manganese-aluminum compound, a lithium-nickel-iron-aluminum compound, or a lithium-nickel-manganese compound, the calcination may be performed at a temperature of 600°C to 1000°C for 5 to 20 hours. Meanwhile, when the lithium-containing compound is a lithium-iron-PO4 compound or a lithium-manganese-iron-PO4 compound, the calcination may be performed at a temperature of 600°C to 800°C for 5 to 20 hours.

[0062] At this time, the lithium-containing compound is characterized by uniformly distributing lithium within the single crystal shape. In addition, the single crystal shape may exist in a state where particles are individually separated, and the average particle size may be 1 um to 5 um. In addition, the single crystal shape may be formed in a layered structure without impurities. On the other hand, a cathode active material for a lithium secondary battery manufactured using a conventional transition metal precursor exhibits a polycrystalline shape (average particle size of 10 um to 50 um) formed by primary and secondary particles clumping together.

[0063] If necessary, after the step (d), a step of mixing nanoparticles having an average particle size of 100 nm to 500 nm into the lithium-containing compound in the single crystal shape can be added to implement a bimodal shape. In other words, the single crystal lithium secondary battery cathode active material is a single crystal small particle, and if nanoparticles having a size of several hundred nm are additionally mixed therein, a bimodal shape can be implemented. Therefore, it is more preferable because it is possible to develop a high-capacity battery by improving the composite density during the manufacture of the electrode plate, while also improving the characteristics even under high-temperature conditions.

[0064] Optionally, after the step (d), a step of forming a surface treatment layer including Al(OH)3, a boron-containing compound, and a silicon-containing compound on the lithium-containing compound in the form of a single crystal may be added. At this time, the boron-containing compound may be included in an amount of 1 to 100 parts by weight and the silicon-containing compound in an amount of 1 to 100 parts by weight, based on 100 parts by weight of the Al(OH)3, and including 1 to 10 parts by weight of the boron-containing compound and 1 to 10 parts by weight of the silicon-containing compound is more optimized in terms of performance improvement, but is not limited thereto.

[0065] The formation of the above surface treatment layer can be accomplished by adding the lithium-containing compound in the form of a single crystal to a surface treatment solution containing Al(OH)3, a boron-containing compound, and a silicon-containing compound. For example, based on 1 kg of the lithium-containing compound in the form of a single crystal, the surface treatment solution can be 300 g to 500 g, and the surface treatment solution can contain 20 g of Al(OH)3, 1 g of B2O3, and 1 g of SiO. x By including 1g, performance can be further optimized.

[0066] Next, it can be performed by mixing and drying at a temperature of 50°C to 150°C for 1 to 10 hours, and then additionally heat treating at a temperature of 200°C to 600°C for 1 to 10 hours. At this time, if the additional heat treatment temperature exceeds 600°C, there is a limitation in that the original effect of the surface treatment cannot be properly exhibited because Al(OH)3 and boron-containing compounds change into crystalline substances.

[0067]

[0068] Cathode active material for lithium secondary batteries

[0069] The present invention provides a positive electrode active material for a lithium secondary battery, which is formed from a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material, and which includes a lithium-containing compound in a single crystal shape having an average particle size of 1 µm to 5 µm.

[0070] A cathode active material for a lithium secondary battery according to the present invention can be formed from a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material. At this time, i) when the second raw material includes both a nickel-containing raw material and a manganese-containing raw material, it may further include at least one doping metal oxide selected from the group consisting of Al2O3, TiO2, ZrO2, MoO6, and Ta2O5, or ii) when the second raw material includes an iron-containing raw material, it may further include a PO4-containing raw material.

[0071] Specifically, the cathode active material for a lithium secondary battery according to the present invention can be manufactured by including the steps of (a) preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material; (b) preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed; (c) drying the nano slurry to prepare nanoparticles; and (d) calcining the dried nanoparticles to prepare a lithium-containing compound in a single crystal shape having an average particle size of 1 μm to 5 μm. Since “steps (a) to (d)” have been described above, a duplicate description thereof will be omitted.

[0072] While the cathode active material for a lithium secondary battery manufactured using a conventional transition metal precursor is a polycrystalline particle (average particle size of 10 μm to 50 μm) formed by agglomeration of primary and secondary particles, the cathode active material for a lithium secondary battery according to the present invention is characterized by a single crystal small particle having an average particle size of 1 μm to 5 μm. At this time, it is characterized by uniformly distributing lithium within the single crystal shape. In addition, the single crystal shape may exist in a state where the particles are individually separated. In addition, the single crystal shape may be formed in a layered structure without impurities.

[0073] A bimodal shape can be realized by additionally mixing nanoparticles having an average particle size of 100 nm to 500 nm into the lithium-containing compound in the single crystal shape. In other words, the positive electrode active material for a lithium secondary battery in the single crystal shape is a small particle in the single crystal shape, and if nanoparticles having a size of several hundred nm are additionally mixed therein, a bimodal shape can be realized. Therefore, it is more preferable because it is possible to develop a high-capacity battery by improving the composite density during the manufacture of the electrode plate, while also improving the characteristics even under high-temperature conditions.

[0074] It may further include a surface treatment layer including Al(OH)3, a boron-containing compound, and a silicon-containing compound formed on the lithium-containing compound in the single crystal shape.

[0075]

[0076] lithium secondary battery

[0077] The present invention provides a lithium secondary battery including the positive electrode active material.

[0078] The lithium secondary battery according to the present invention includes the positive electrode active material. Since the “positive electrode active material” has been described above, a duplicate explanation will be omitted.

[0079] Specifically, a lithium secondary battery can be provided, which includes a positive electrode including the positive electrode active material, a conductive material, and a binder; a negative electrode including the negative electrode active material; and an electrolyte. The lithium secondary battery is formed by including a positive electrode, a negative electrode, and a separator, and as a separator that insulates the electrodes between the positive electrode and the negative electrode, a commonly known polyolefin-based separator, a composite separator in which an organic / inorganic composite layer is formed on the polyolefin-based substrate, etc. can all be used, and is not particularly limited thereto.

[0080] In addition, a medium- or large-sized battery module or battery pack including a plurality of the lithium secondary batteries electrically connected thereto can be provided. The medium- or large-sized battery module or battery pack can be used as a power source for one or more medium- or large-sized devices selected from the group consisting of power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric trucks; electric commercial vehicles; and power storage systems.

[0081] As reviewed above, the method for manufacturing a cathode active material for a lithium secondary battery according to the present invention excludes the use of a transition metal precursor, and by dissolving and dispersing each raw material (raw material in the form of an oxide or a form of a hydroxide) into a solution, wet nanomilling the solution, and then drying (particularly, mechanical drying after putting it into a planetary dispersive mixer), a lithium-containing compound in the form of a single crystal having an average particle size of 1 ㎛ to 5 ㎛ can be easily manufactured with high efficiency. In some cases, by using raw materials obtained from lithium ion waste batteries through a wet process as each raw material, there is an advantage in that environmental problems, particularly water pollution problems, that occur during the manufacture of transition metal precursors can be solved.

[0082] The cathode active material for a lithium secondary battery manufactured according to the present invention has the advantage of stabilizing the crystal structure compared to a polycrystalline form by uniformly distributing lithium within a single crystal form. Accordingly, it has excellent structural stability under high-voltage charging conditions, thereby securing high-capacity characteristics of a lithium secondary battery, and also has excellent characteristics under high-temperature conditions, thereby securing high-temperature lifespan, recovery, and maintenance characteristics of a lithium secondary battery. In particular, it has excellent thermal stability compared to a polycrystalline form, thereby improving the stability of a lithium secondary battery.

[0083] That is, a lithium secondary battery using a high-performance and low-cost cathode active material manufactured according to the present invention has excellent performance advantages such as discharge capacity and efficiency, C-rate, and room temperature and high temperature life characteristics.

[0084]

[0085] Hereinafter, preferred examples are presented to aid in understanding the present invention. However, the following examples are provided solely to facilitate a better understanding of the present invention, and the scope of the present invention is not limited by the following examples.

[0086] [Example]

[0087] Example 1

[0088] Li2CO3 was prepared as a lithium-containing raw material. In addition, Ni(OH)2 was prepared as a nickel-containing raw material, Co3O4 as a cobalt-containing raw material, and Mn3O4 as a manganese-containing raw material were prepared in a composition ratio (equivalent ratio) of Ni:Co:Mn=6:2:2. Each raw material was dissolved and dispersed using water as a solvent under the condition of Li / Me=1.5 using a stirrer as shown in Fig. 1(a). At this time, the weight ratio of each raw material to water was changed to 1:2 to 1:4, and as a result of conducting the experiment, it was confirmed that the dissolution and dispersion effect was the best when the weight ratio of each raw material to water was 1:3.

[0089] The dissolved and dispersed solution was wet-nanomilled for 1 to 3 hours using a wet nano-milling facility such as Fig. 1(b) to produce a nano slurry, and the particle distribution was measured using a particle size analyzer (PSA) (Fig. 1(c)). As a result, after wet-nanomilling at a speed of 3,000 rpm for 2 hours, the particle distribution was measured to be D50 = 0.1 to 0.5 ㎛ (preferably 0.1 to 0.2 ㎛) and Dmax < 1 ㎛. In this case, it can be produced as a positive electrode active material for a lithium secondary battery with excellent performance through uniform particle growth after mechanical drying and calcination.

[0090] After the nano slurry was introduced into a planetary dispersive mixer as shown in Fig. 1(d), the nanoparticles were manufactured by mechanical drying by blowing dry air or dry nitrogen gas under vacuum conditions. At this time, a jacket having a circulation path formed on the outer surface of the planetary dispersive mixer through which a heated fluid of approximately 100°C circulates was additionally provided.

[0091] After classifying the nanoparticles through -325 mesh, they were calcined at a temperature of 850 to 900 °C for 10 hours in an oxygen atmosphere, and then pulverized using a pulverizer to produce a lithium-containing compound [LNCM622] (D50 = 1 to 5 μm) in the form of a single crystal.

[0092] Next, a slurry of positive electrode active material was prepared with a weight ratio of single crystal lithium-containing compound [LNCM622]: Super P conductive agent: PVDF binder = 96:2:2, and then a positive electrode plate was manufactured under the condition of a plate density of 3.3 g / cc, and a coin cell was manufactured in a dry room using a Li metal negative electrode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. Afterwards, the room temperature life and 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0093] Example 2

[0094] Li2CO3 was prepared as a lithium-containing raw material. In addition, Ni(OH)2 was used as a nickel-containing raw material, Co3O4 was used as a cobalt-containing raw material, Mn3O4 was used as a manganese-containing raw material, and Al2O3 powder with a size of 10 μm or less was used as an aluminum-containing raw material, with a composition ratio (equivalent ratio) of Ni:Co:Mn:Al=6:1:2.3:0.7. A single crystal lithium-containing compound [LNCMA613] (D50 = 1-5 μm) and a coin cell were manufactured using the same method as in Example 1. Thereafter, the room temperature life and the high temperature life at 45°C were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0095] Comparative Example 1

[0096] NCMA613 precursor [Ni 0.6 Co 0.1 Mn 0.23 Al 0.07 (OH)2, product of China Zhongwei, D50 = 10~11um] and Li2CO3 [made in China] were measured under the condition of Li / Me = 1.05, and then dry-mixed for 1 hour using a mixer, and then calcined at 850~900℃ for 10 hours in an air atmosphere. Then, it was pulverized using a roll mill and an ACM pulverizer, and then classified to -325 mesh to obtain a lithium-containing compound in the form of a polycrystal, Ni 0.6 Co 0.1 Mn 0.23 Al 0.07 O2[LNCMA613] (D50 = 10~50 ㎛) was prepared.

[0097] Next, as a lithium-containing compound, Ni 0.6 Co 0.1 Mn 0.23 Al 0.07O2[LNCMA613]: Super P conductive agent: PVDF binder = 96:2:2 weight ratio to make a cathode active material slurry, and then manufactured a cathode plate with a plate density of 3.3 g / cc, and manufactured a coin cell in a dry room using a Li metal anode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. After that, the room temperature life and 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0098] FIG. 2(a) and (b) are graphs comparing the C-rate and 0.1C capacity in the 4.5-3.0 V voltage range of the coin cells according to Example 2 and Comparative Example 1, respectively. It is confirmed that the coin cell according to Example 2 has superior C-rate and 0.1C capacity in the 4.5-3.0 V voltage range compared to the coin cell according to Comparative Example 1, as it is mechanically dried after being introduced into a wet nanomilling and planetary dispersive mixer while excluding the use of an NCMA613 precursor.

[0099] Example 3

[0100] Li2CO3 was prepared as a lithium-containing raw material. In addition, a lithium-containing compound [LNFA] (D50 = 1-5 μm) and a coin cell in a single crystal form were manufactured in the same manner as in Example 1, except that NiO was replaced as a nickel-containing raw material, Fe2O3 was replaced as an iron-containing raw material, and Al2O3 was replaced as an aluminum-containing raw material in a composition ratio (equivalent ratio) of Ni:Fe:Al=8.5:0.52:0.91. Thereafter, the room temperature life and the high temperature life at 45°C were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0101] Comparative Example 2

[0102] Journal of Power Sources.2020. Doi:10.1016 / j.jpowsour.2020.228389("a new cobalt-free layered cathode material for advanced Li-ion batteries"), as an NFA precursor, Ni x Fe y Al z As a lithium-containing compound in a polycrystalline form from (OH)2, Li 1.0 Ni 0.85 Fe 0.052 Al 0.091 O2 (D50 = 10~50 ㎛) was prepared.

[0103] Next, as a lithium-containing compound, Li 1.0 Ni 0.85 Fe 0.052 Al 0.091 O2[NFA]: Super P conductive agent: PVDF binder = 96:2:2 weight ratio to make a cathode active material slurry, and then manufactured a cathode plate with a plate density of 3.3 g / cc, and manufactured a coin cell in a dry room using a Li metal anode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. After that, the room temperature life and 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0104] FIGS. 3(a) and (b) are graphs comparing the 0.1C capacity in the voltage ranges of 4.5-3.0 V and 4.3-3.0 V of the coin cells according to Example 3 and Comparative Example 2, respectively. It is confirmed that the coin cell according to Comparative Example 2 has a 0.1C capacity of about 160 mAh / g in the voltage range of 4.3-3.0 V, whereas the coin cell according to Example 3 has an improved discharge capacity of about 170 mAh / g in the voltage range of 4.3-3.0 V. This can be seen as a result of mechanical drying after putting into a wet nanomilling and planetary dispersive mixer while excluding the use of an NFA precursor.

[0105] Example 4

[0106] Li2CO3 was prepared as a lithium-containing raw material. In addition, a lithium-containing compound [5V LNMO] (D50 = 1-5 μm) and a coin cell in a single crystal form were manufactured using the same method as in Example 1, except that Ni(OH)2 was replaced with Ni(OH)2 as a nickel-containing raw material and Mn3O4 was replaced with Mn3O4 as a manganese-containing raw material at a composition ratio (equivalent ratio) of Ni:Mn=2.5:7.5. Thereafter, the room temperature life and the high temperature life at 45°C were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage range of 4.9-3.0 V.

[0107] Comparative Example 3

[0108] NMO precursor [Ni 0.25 Mn 0.75 (OH)2, a product of Zhongwei, China, D50 = 10~11um] and Li2CO3 [made in China] were measured under the condition of Li / Me = 1.03, and then dry-mixed for 1 hour using a mixer, and then calcined at 800~850℃ for 10 hours in an air atmosphere. Then, it was pulverized using a roll mill and an ACM pulverizer, and then classified to -325 mesh to obtain a lithium-containing compound in the form of a polycrystal, LiNi 0.25 Mn 0.75O4[5V LNMO] (D50 = 10~50 ㎛) was prepared.

[0109] Next, as a lithium-containing compound, LiNi 0.25 Mn 0.75 O4[5V LNMO]: Super P conductive agent: PVDF binder = 96:2:2 weight ratio to make a cathode active material slurry, and then manufactured a cathode plate with a plate density of 3.3 g / cc, and manufactured a coin cell in a dry room using a Li metal anode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. After that, the room temperature cycle life and 45 ℃ high temperature cycle life were evaluated under 0.1 C capacity, C-rate, and 1 C / 1 C conditions in the voltage range of 4.9-3.0 V.

[0110] FIG. 4(a) is a SEM photograph comparing lithium-containing compounds according to Example 4 and Comparative Example 3. It is confirmed that the lithium-containing compound according to Example 4 has a single crystal shape with individual particles having an average particle size of 1 to 5 um, while the lithium-containing compound according to Comparative Example 3 has a polycrystal shape formed by primary and secondary particles clumping together.

[0111] In addition, FIGS. 4(b) and (c) are graphs comparing the 0.1C capacity and room temperature lifespan in the 4.9-3.0 V voltage range of the coin cells according to Example 4 and Comparative Example 3, respectively. It is confirmed that the coin cell according to Example 4 has a discharge capacity at a similar level as the coin cell according to Comparative Example 3, while the room temperature lifespan characteristics are significantly improved. This can be seen as a result of lithium being uniformly distributed within the single crystal shape by excluding the use of an NMO precursor and mechanically drying after introduction into a wet nanomilling and planetary dispersive mixer.

[0112] Example 5

[0113] Li2CO3 was prepared as a lithium-containing raw material. In addition, a lithium-containing compound [LNCM523] (D50 = 1-5 μm) and a coin cell in a single crystal form were manufactured in the same manner as in Example 1, except that Ni(OH)2 was replaced with Ni(OH)2 as a nickel-containing raw material and Mn3O4 was replaced with Mn3O4 as a manganese-containing raw material in a composition ratio (equivalent ratio) of Ni:Co:Mn=5:2:3. Thereafter, the room temperature life and the high temperature life at 45°C were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0114] Comparative Example 4

[0115] NCM523 precursor [Ni 0.5 Co 0.2 Mn 0.3 (OH)2, a product of Zhongwei, China, D50 = 10~11um] and Li2CO3 [made in China] were measured under the condition of Li / Me = 1.05, and then dry-mixed for 1 hour using a mixer, and then calcined at 900~950℃ for 10 hours in an air atmosphere. Then, it was pulverized using a roll mill and an ACM pulverizer, and then classified to -325 mesh to obtain a lithium-containing compound in the form of a polycrystal, LiNi 0.5 Co 0.2 Mn 0.3 O2[LNCM523] (D50 = 10~50 ㎛) was prepared.

[0116] Next, as a lithium-containing compound, LiNi 0.5 Co 0.2 Mn 0.3O2[LNCM523]: Super P conductive agent: PVDF binder = 96:2:2 weight ratio to make a cathode active material slurry, and then manufactured a cathode plate with a plate density of 3.3 g / cc, and manufactured a coin cell in a dry room using a Li metal anode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. After that, the room temperature life and 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0117] FIG. 5(a) is a graph showing an XRD pattern of a lithium-containing compound according to Example 5. The lithium-containing compound according to Example 5 shows a single-phase peak of a layered structure, confirming that it is formed in a layered structure without impurities.

[0118] In addition, FIG. 5(b) is a SEM photograph comparing the lithium-containing compounds according to Example 5 and Comparative Example 4. It is confirmed that the lithium-containing compound according to Example 5 has a single crystal shape with an average particle size of 1 to 5 um in which the particles are individually separated, but the lithium-containing compound according to Comparative Example 4 has a polycrystal shape formed by primary and secondary particles clumping together.

[0119] In addition, FIG. 5(c) is a graph comparing the 0.1C capacity in the 4.3-3.0 V voltage range of the coin cells according to Example 5 and Comparative Example 3, and it is confirmed that the coin cell according to Example 5 has improved discharge capacity and efficiency compared to the coin cell according to Comparative Example 3. This is because lithium was uniformly distributed within the single crystal shape formed in a layered structure by excluding the use of the NCM523 precursor and mechanically drying it after being introduced into a wet nanomilling and planetary dispersive mixer, and no impurities were generated.

[0120] Example 6

[0121] LiOH was prepared as a lithium-containing raw material. In addition, Ni(OH)2 was used as a nickel-containing raw material and Mn3O4 was used as a manganese-containing raw material, and these were all raw materials obtained through a wet process from lithium-ion spent batteries. Specifically, they were obtained in the form of an intermediate hydroxide by dissolving a lithium-ion spent battery positive electrode plate with acid and then precipitating it using a cation metal titration method, or in the form of a final oxide by a heat treatment and calcination process. That is, a single crystal lithium-containing compound [Co-free LNM8020_used recycled metal] (D50 = 1-5 μm) and a coin cell were manufactured through the same method as in Example 1, except that the composition ratio (equivalent ratio) of Ni:Mn = 8:2 was replaced and A = Al2O3 [2,000-3,000 ppm] and B = TiO2 [500-1,000 ppm] were additionally added as doping metal oxides. Afterwards, the room temperature life and 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V and 4.5-3.0 V.

[0122] FIG. 6(a) is a graph showing the 0.1C capacity and high-temperature lifespan of a coin cell according to Example 6 in the voltage ranges of 4.3-3.0 V and 4.4-3.0 V, respectively. It is confirmed that the coin cell according to Example 6 has excellent discharge capacity and also excellent high-temperature lifespan characteristics.

[0123] Example 7

[0124] First, Fe2O3 as an iron-containing raw material and (NH4)H2PO4 as a PO4-containing raw material were prepared in a composition ratio (equivalent ratio) of Fe:PO4=1:0.9~1:1.05, and then they were uniformly mixed, pulverized, and dried, and then pre-calcined for the first time at a temperature of 160~180℃ for 15~18 hours, and then pre-calcined for the second time at a temperature of 720~780℃ for 10~15 hours to produce single-phase single crystal FePO4. In addition, Li2CO3 as a lithium-containing raw material and a carbon source were prepared. Each raw material was dissolved and dispersed using water as a solvent under the condition of Li / Me=1.05 using a stirrer as shown in Fig. 1(a). At this time, the weight ratio of each raw material to water was changed to 1:2~1:4, and as a result of the experiment, it was confirmed that the dissolution and dispersion effect was the best when the weight ratio of each raw material to water was 1:3. Glucose 4-6 wt% was used as a carbon source, and citric acid 1-2 wt% was used to facilitate dispersion.

[0125] The dissolved and dispersed solution was wet-nanomilled at a speed of 3,000 rpm for 2 hours using the wet nano-mill equipment employed in Example 1 to produce a nano slurry.

[0126] Nano slurry was introduced into the planetary dispersive mixer employed in Example 1, and then mechanically dried by blowing dry air under vacuum conditions to produce nanoparticles. At this time, a jacket having a circulation path formed on the outer surface of the planetary dispersive mixer through which a heated fluid of approximately 100°C circulates was additionally provided.

[0127] The nanoparticles were calcined at a temperature of 730 to 770 °C for 10 hours under a nitrogen atmosphere and then pulverized using a pulverizer to produce a lithium-containing compound [LFP] (D50 = 1 to 5 μm) in the form of a single crystal.

[0128] Next, a slurry of positive electrode active material was prepared with a weight ratio of single crystal lithium-containing compound [LFP]: Super P conductive agent: PVDF binder = 95:2.5:2.5, and then a positive electrode plate was manufactured under the condition of a plate density of 2.0 g / cc, and a coin cell was manufactured in a dry room using a Li metal negative electrode and EC / DMC / DEC [1 / 1 / 1] + 1 M LiPF6 electrolyte. Afterwards, the room temperature cycle life and 45 ℃ high temperature cycle life were evaluated under the conditions of 0.1 C capacity, C-rate, and 1 C / 1 C in the voltage range of 3.7-2.0 V.

[0129] Comparative Example 5

[0130] Using FP precursors manufactured by the coprecipitation method [FePO4, manufactured by Zhongwei, China, hundreds of nm size product (D50 = 100~300 nm)] and Li2CO3 [manufactured in China], the weights were measured under the condition of Li / Me = 1.05, and then glucose was added in an amount of 3~5 wt% of the total weight, dry-mixed using a mixer for 1 hour, and then calcined at 600~700 ℃ for 10 hours under a nitrogen atmosphere. Then, the mixture was pulverized using a roll mill and an ACM pulverizer, and then classified through -325 mesh to manufacture LiFePO4[LFP] (D50 = 100~500 nm) as a lithium-containing compound.

[0131] Next, a slurry of positive electrode active material was prepared with a weight ratio of LiFePO4[LFP]: Super P conductive agent: PVDF binder = 95:2.5:2.5 as a lithium-containing compound, and then a positive electrode plate was manufactured under the condition of a plate density of 2.0 g / cc, and a coin cell was manufactured in a dry room using a Li metal negative electrode and EC / DMC / DEC[1 / 1 / 1] + 1 M LiPF6 electrolyte. Afterwards, the room temperature life and 45℃ high temperature life were evaluated under the conditions of 0.1C capacity, C-rate, and 1C / 1C in the voltage range of 3.7-2.0 V.

[0132] Fig. 7(a) is an SEM photograph comparing a lithium-containing compound according to Example 7, and it is confirmed that the lithium-containing compound according to Example 7 has a single crystal shape with individually separated particles and an average particle size of 1 to 5 um.

[0133] In addition, Fig. 7(b) is a graph comparing the XRD patterns of the lithium-containing compound according to Example 7 at different firing temperatures. When the firing temperature is 730 to 770°C, the lithium-containing compound according to Example 7 shows a single-phase peak of a layered structure, confirming that it is formed in a layered structure without generating impurities.

[0134] FIGS. 7(c) to (e) are graphs comparing the 0.1C capacity, high-temperature lifespan, and C-rate in the 3.7-2.0 V voltage range of the coin cells according to Example 7 and Comparative Example 5, respectively. It is confirmed that the coin cell according to Example 7 has improved discharge capacity and efficiency, and both high-temperature lifespan characteristics and C-rate are excellent compared to the coin cell according to Comparative Example 5. This is because the use of an FP precursor manufactured by a co-precipitation method was excluded, and by mechanically drying after being introduced into a wet nanomilling and planetary dispersive mixer, lithium was uniformly distributed within the single crystal shape of the olivine crystal structure, and no impurities were generated.

[0135] Example 7-1

[0136] A lithium-containing compound in a bimodal shape was prepared by mixing the LiFePO4[LFP] (D50 = 1-5 ㎛) manufactured in Example 7 with the LiFePO4[LFP] (D50 = 100-500 nm) manufactured in Comparative Example 5 in a weight ratio of 7:3, and a coin cell was manufactured. Afterwards, 3 Ton / cm 2 The plate density and plate energy density were measured by pressing under pressure, and the results are shown in Table 1.

[0137] mAh / gM. voltage(V) electrode density(g / cc) energy density (mAh / cc) Example 7-1 1553.22.9 51463.2 Comparative example 51553.22.4 31166.4

[0138] As shown in Table 1, the coin cell according to Example 7-1 showed an increase in electrode conductivity by approximately 21% and an increase in energy density by approximately 25% compared to the coin cell according to Comparative Example 5. This can be seen as a result of optimally improving the composite density during the manufacture of the electrode plate.

[0139] Example 8

[0140] LiOH was prepared as a lithium-containing raw material. In addition, while replacing Ni(OH)2 as a nickel-containing raw material, Co3O4 as a cobalt-containing raw material, and Mn3O4 as a manganese-containing raw material with a composition ratio (equivalent ratio) of Ni:Co:Mn=8.3:1.2:0.5 and additionally adding MoO6[3,000 ppm] as a doping metal oxide, a lithium-containing compound [LNMCM83] (D50=1-5 ㎛) and a coin cell in a single crystal form were manufactured using the same method as in Example 1. Thereafter, the room temperature life and the 45 ℃ high temperature life were evaluated under 0.1C capacity, C-rate, and 1C / 1C conditions in the voltage ranges of 4.3-3.0 V, 4.4-3.0 V, and 4.5-3.0 V.

[0141] Figure 8 is a graph confirming the 0.1C capacity in the voltage range of 4.3-3.0 V of a coin cell according to Example 5. It is confirmed that the coin cell according to Example 5 has considerably excellent discharge capacity and efficiency. This can be seen as MoO6 being particularly preferable as a doping metal oxide.

[0142] The foregoing description of the present invention is for illustrative purposes only. Those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. (a) A step of preparing a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material; (b) a step of preparing a nano slurry by wet nanomilling a solution in which the first raw material and the second raw material are dissolved and dispersed; (c) a step of drying the nano slurry to produce nano particles; and (d) A method for producing a positive electrode active material for a lithium secondary battery, comprising the step of producing a lithium-containing compound in a single crystal shape having an average particle size of 1 ㎛ to 5 ㎛ by calcining the dried nanoparticles.

2. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that the second raw material in the above step (a) is in the form of an oxide or a hydroxide.

3. In paragraph 1, In step (a) above i) When the second raw material includes both a nickel-containing raw material and a manganese-containing raw material, it additionally includes one or more doping metal oxides selected from the group consisting of Al2O3, TiO2, ZrO2, MoO6 and Ta2O5, or ⅱ) A method for producing a positive electrode active material for a lithium secondary battery, characterized in that when the second raw material includes an iron-containing raw material, a PO4-containing raw material is additionally included.

4. In paragraph 3, ⅱ) A method for producing a positive electrode active material for a lithium secondary battery, characterized in that a step of dry mixing a second raw material including the iron-containing raw material and the PO4-containing raw material, performing a first preliminary firing at a temperature of 150°C to 200°C, and then performing a second preliminary firing at a temperature of 450°C to 800°C is added.

5. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that the volume ratio of the raw materials and the solvent in the solution in the step (b) is 1:1 to 1:

5.

6. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that in the step (b), wet nanomilling is performed at a speed of 1,000 rpm to 5,000 rpm for 1 to 5 hours.

7. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that in the particle distribution of the nano slurry in the above step (b), 0.1 ㎛ ≤ D50 ≤ 0.5 ㎛ and Dmax < 1 ㎛.

8. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that in the step (c) above, drying is performed through mechanical drying in a planetary dispersive mixer.

9. In paragraph 8, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that a jacket having a circulation path formed on the outer surface of the planetary dispersive mixer through which a heating fluid circulates is additionally provided, and the heating fluid maintains a temperature of 50°C to 200°C.

10. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that drying in the above step (c) is performed under vacuum conditions.

11. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that in the above step (d), sintering is performed at a temperature of 600°C to 1000°C for 5 to 20 hours.

12. In paragraph 1, A method for producing a positive electrode active material for a lithium secondary battery, characterized in that after the above step (d), a step of forming a surface treatment layer containing Al(OH)3, a boron-containing compound, and a silicon-containing compound on the lithium-containing compound in the form of a single crystal is added.

13. Formed from a first raw material including a lithium-containing raw material and a second raw material including at least one selected from the group consisting of a nickel-containing raw material, a cobalt-containing raw material, a manganese-containing raw material, an iron-containing raw material, and an aluminum-containing raw material, A cathode active material for a lithium secondary battery comprising a lithium-containing compound in a single crystal shape with an average particle size of 1 ㎛ to 5 ㎛.

14. In paragraph 13, A cathode active material for a lithium secondary battery, characterized in that a bimodal shape is realized by additionally mixing nanoparticles having an average particle size of 100 nm to 500 nm into the lithium-containing compound having the single crystal shape.

15. In paragraph 13, A positive electrode active material for a lithium secondary battery, characterized in that it further comprises a surface treatment layer comprising Al(OH)3, a boron-containing compound, and a silicon-containing compound, formed on the lithium-containing compound in the form of a single crystal.

16. In paragraph 13, i) When the second raw material includes both a nickel-containing raw material and a manganese-containing raw material, it additionally includes one or more doping metal oxides selected from the group consisting of Al2O3, TiO2, ZrO2, MoO6 and Ta2O5, or ⅱ) A positive electrode active material for a lithium secondary battery, characterized in that when the second raw material includes an iron-containing raw material, it additionally includes a PO4-containing raw material.

17. A lithium secondary battery comprising a positive electrode active material according to any one of claims 13 to 16.

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