Method of manufacturing positive electrode active material composite

Abstract

The present invention relates to a method of manufacturing a positive electrode active material composite. The method of manufacturing a positive electrode active material composite according to an embodiment of the present invention comprises the steps of: preparing positive electrode active material particles containing a lithium composite oxide; mixing an ionic substance represented by chemical formula 1 and an initiator to obtain a coating composition; and mixing the positive electrode active material particles and the coating composition to prepare the positive electrode active material composite.

Description

Method for manufacturing a positive electrode active material complex

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

[0002] Recently, as the required energy density of batteries has increased rapidly, the development of high-capacity lithium-ion batteries has become urgent. To this end, research is actively underway to replace conventional anode materials, such as graphite or silicon, with lithium metal, or to incorporate cathode materials with high energy density into the electrodes.

[0003] However, as the anode becomes thicker for high energy density, it is difficult to secure stable battery performance and lifespan characteristics, so there is practically a limit to increasing the thickness.

[0004] For example, such thick-film cathodes have a problem in that the cathode active material is non-uniformly dispersed. This problem causes non-uniform lithium ion flow characteristics and leads to non-uniform charge / discharge characteristics and polarization phenomena along the thickness direction.

[0005] Therefore, research and development are required for cathode active materials that can be uniformly dispersed in thick-film cathodes to induce uniform lithium ion flow characteristics.

[0006] One aspect of the present invention is to provide a method for manufacturing a cathode active material composite having excellent dispersibility at the cathode.

[0007] The problems of the present invention are not limited to those described above. A person skilled in the art to which the present invention pertains will have no difficulty understanding additional problems of the present invention from the overall contents of this specification.

[0008] A method for manufacturing a positive electrode active material composite according to one embodiment of the present invention comprises the steps of: preparing positive electrode active material particles comprising a lithium composite oxide; mixing an ionic material represented by Formula 1 and an initiator to obtain a coating composition; and mixing the positive electrode active material particles and the coating composition to manufacture a positive electrode active material composite.

[0009] [Chemical Formula 1]

[0010]

[0011] (In the above Chemical Formula 1, R1 is a substituted or unsubstituted (C1-C10) hydrocarbon group with n, n is an integer from 1 to 3, X is N(CF3SO2)2, N(FSO2)2 or CF3SO3, L1 is each independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene or a combination thereof, and the hydrogen of L1 may each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.)

[0012] In addition, in the method for manufacturing the above-mentioned positive electrode active material composite, in the step of manufacturing the above-mentioned positive electrode active material composite, the mixing may be performed by stirring at a speed of 1500 rpm or higher.

[0013] In addition, in the method for manufacturing the above-mentioned positive electrode active material composite, in the step of obtaining the coating composition, the coating composition may further include a compound containing an acrylate group.

[0014] In addition, in the method for manufacturing the above-mentioned positive active material composite, the compound may contain three or more acrylate groups.

[0015] In addition, in the method for manufacturing the above-mentioned positive electrode active material composite, the ionic material and the compound containing the acrylate group may be mixed in a weight ratio of 1:0.05 to 0.3.

[0016] In addition, in the method for manufacturing the above-mentioned positive active material composite, the positive active material particles and the coating composition may be mixed in a weight ratio of 1:0.001 to 0.06.

[0017] In addition, in the method for manufacturing the above-mentioned positive electrode active material composite, the initiator may include an azo compound.

[0018] In addition, in the method for manufacturing the above-mentioned positive active material composite, the positive active material particles may include one or more of a single-crystal active material and a polycrystalline active material.

[0019] In addition, in the method for manufacturing the above-mentioned positive active material composite, the positive active material particles may include a positive active material represented by the following chemical formula 2.

[0020] [Chemical Formula 2]

[0021] Li x [Ni a Co b Mn c M 1 d ]O2

[0022] (In the above chemical formula 2, M 1 ...is one or more selected from Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, P, Y, Na, and Ca, and 0.8≤x≤1.3, 0.5≤a≤1.0, 0≤b≤0.5, 0≤c≤0.5, 0≤d≤0.2, and a+b+c+d=1.)

[0023] In addition, in the method for manufacturing the above-described positive active material composite, the positive active material particles may include a first positive active material particle having an average particle size (D50) of 10 to 20 μm; and a second positive active material particle having an average particle size (D50) of 1 to 10 μm.

[0024] In addition, in the method for manufacturing the above-mentioned positive electrode active material composite, the weight ratio of the first positive electrode active material particle and the second positive electrode active material particle may be 1:0.1 to 0.5.

[0025] In addition, in the method for manufacturing the above-mentioned positive active material composite, the ionic material may be represented by the following chemical formula 3 or chemical formula 4.

[0026] [Chemical Formula 3]

[0027]

[0028] [Chemical Formula 4]

[0029]

[0030] (In the above chemical formulas 3 and 4, R2 is a substituted or unsubstituted (C1-C10) hydrocarbon group, X is N(CF3SO2)2, N(FSO2)2, or CF3SO3, L1 is each independently a directly bonded (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, L2 is (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, and the hydrogens of L1 and L2 may each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.)

[0031] In addition, the method for manufacturing the above-mentioned positive electrode active material composite may further include a step of heat-treating the coating composition at a temperature of 30 to 150°C prior to the step of manufacturing the above-mentioned positive electrode active material composite.

[0032] The method for manufacturing a positive electrode active material composite according to the present invention can produce a positive electrode active material composite having excellent dispersibility and rapid electrolyte wettability through a simple process.

[0033] The various and beneficial advantages and effects of the present invention are not limited to those described above and will be more easily understood in the process of explaining specific embodiments of the present invention.

[0034] Figure 1 is a graph showing the FT-IR analysis results of Example 1 and Comparative Example 1.

[0035] Figure 2 is a graph showing the capacity realization rate for the discharge rate of the example and comparative example.

[0036] Preferred embodiments of the present invention are described below. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below.

[0037] In addition, embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the relevant technical field.

[0038] In describing the embodiments of the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or conventions of the user or operator. Therefore, such definitions should be based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should not be limited in any way. Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form.

[0039] In this specification, expressions such as “include” or “comprising” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts or combinations thereof other than those described.

[0040] Unless otherwise specifically defined in this specification, % units mean weight %.

[0041] The term "CA-CB" in this specification may mean "having a carbon number of A or more and B or less."

[0042] The present invention will be described in detail below through each embodiment or example of the invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the patent claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0043] According to one embodiment of the present invention, a method for manufacturing a positive electrode active material composite is provided. A method for manufacturing a positive electrode active material composite according to one embodiment of the present invention comprises the steps of: preparing positive electrode active material particles comprising a lithium composite oxide; mixing an ionic material represented by the following chemical formula 1 and an initiator to obtain a coating composition; and mixing the positive electrode active material particles and the coating composition to manufacture a positive electrode active material composite.

[0044] [Chemical Formula 1]

[0045]

[0046] In the above chemical formula 1, R1 is a substituted or unsubstituted (C1-C10) hydrocarbon group of n, n is an integer from 1 to 3, X is N(CF3SO2)2, N(FSO2)2 or CF3SO3, L1 is each independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene or a combination thereof, and the hydrogen of L1 can each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.

[0047] In this specification, "hydrocarbon group" may include a linear or branched alkyl group; a linear or branched alkylene group; a saturated cyclic aliphatic hydrocarbon group; an unsaturated cyclic aliphatic hydrocarbon group; an aryl group; an arylene group; an arylalkyl group; an arylalkylene group; or a combination thereof. Additionally, the hydrocarbon group may be substituted with one or more substituents selected from the group consisting of -O-, -OC(O)-, -OC(O)O-, -NHCO-, and -NHC(O)O-. Specifically, the "hydrocarbon group" may include a linear or branched (C1-C10)alkyl group; a linear or branched (C1-C10)alkylene group; a (C3-C10)cycloalkyl group; a (C3-C10)cycloalkylene group; a (C3-C10)cycloalkenylene group; or a combination thereof.

[0048] In this specification, "substitution" may mean that one or more hydrogen atoms bonded to a hydrocarbon group are substituted with a halogen, nitro, cyano, (C1-C7)alkoxy, hydroxy, or carboxyl.

[0049] As a specific example, in the above chemical formula 1, the substituted or unsubstituted (C1-C10) hydrocarbon group of R1 may be a (C1-C10) alkyl or a (C1-C10) alkylene. Additionally, as a specific example, R1 may be a substituted or unsubstituted (C1-C8) hydrocarbon group of n, more specifically a (C1-C6) hydrocarbon group, and may be, for example, a (C1-C6) alkyl or a (C1-C6) alkylene.

[0050] As a specific example, in the above chemical formula 1, R1 is a substituted or unsubstituted (C1-C6) hydrocarbon group of n, n is 1 or 2, X is N(CF3SO2)2, N(FSO2)2 or CF3SO3, and L1 may each be independently a direct bond.

[0051] In a method for manufacturing a positive electrode active material composite according to one embodiment of the present invention, the coating composition containing the polymer is composited with the positive electrode active material particles to form a coating layer, thereby providing excellent dispersibility at the positive electrode. For example, the coating layer located on the surface of the positive electrode active material particles may be a coating layer composed of a linear polymer or a network polymer coating layer having crosslinking points. Specifically, when forming an electrode using a slurry containing the positive electrode active material composite, a network polymer coating layer may be preferred in terms of maintaining the structural safety of the coating layer. The coating layer may be an conformal coating layer conformally coated on the surface of the positive electrode active material particles.

[0052] By including the cathode active material composite manufactured by the above method as the active material of the cathode, the affinity of the cathode to the electrolyte is improved by the coating layer of the cathode active material composite, thereby enabling rapid electrolyte wettability. Accordingly, the lithium secondary battery containing the cathode active material composite can maintain a smooth flow of lithium ions and can have excellent ion conductivity, lifespan characteristics, and charge / discharge efficiency at high temperatures.

[0053] In the step of preparing positive electrode active material particles, positive electrode active material particles comprising a lithium composite oxide are prepared. In this step, the lithium composite oxide may be prepared as a compound capable of reversibly intercalating and deintercalating lithium (a lithated intercalation compound). For example, the positive electrode active material particles prepared in this step are not particularly limited as long as they are known as conventional positive electrode active materials, and the positive electrode active material particles may include one or more selected from single-crystal active materials and polycrystalline active materials.

[0054] For example, in this step, one or more composite oxides of a metal selected from cobalt, manganese, nickel, and combinations thereof and lithium can be prepared as positive electrode active material particles, and specific examples thereof may include compounds represented by any one of the following chemical formulas.

[0055] Li a A 1-b B b D2(wherein 0.90 ≤ a ≤ 1.8, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α T α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α T2(wherein, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α(In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α T α (In the above equation, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α T2(wherein, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2(wherein the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); and Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); in the preceding formula, A is Ni, Co, Mn or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; T is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; I is Cr, V, Fe, Sc, Y or a combination thereof; and J may be V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0056] More specifically, the positive active material particles may include a positive active material represented by the following chemical formula 2.

[0057] [Chemical Formula 2]

[0058] Li x [Ni a Co b Mn c M 1 d ]O2

[0059] In the above chemical formula 2, M 1 is one or more selected from Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, P, Y, Na and Ca, and 0.8≤x≤1.3, 0.5≤a≤1.0, 0≤b≤0.5, 0≤c≤0.5, 0≤d≤0.2, and a+b+c+d=1.

[0060] Specifically, M in the above chemical formula 2 1It may be a doping element that can be included in the positive electrode active material particles and may be appropriately selected as needed. In addition, in the above chemical formula 2, x represents the molar ratio of lithium in the positive electrode active material and may be 0.8≤x≤1.3, 0.85≤x≤1.25, or 0.9≤x≤1.2.

[0061] In the above Chemical Formula 2, a represents the molar ratio of nickel among the metals excluding lithium in the positive electrode active material, and may be 0.5 ≤ a ≤ 1.0, 0.52 ≤ a ≤ 0.98, or 0.55 ≤ a ≤ 0.95. In the above Chemical Formula 2, b represents the molar ratio of cobalt among the metals excluding lithium in the positive electrode active material, and may be 0 ≤ b ≤ 0.5, 0.01 ≤ b ≤ 0.58, or 0.01 ≤ b ≤ 0.55. In the above Chemical Formula 2, c represents the molar ratio of manganese among the metals excluding lithium in the positive electrode active material, and may be 0 ≤ c ≤ 0.5, 0.01 ≤ c ≤ 0.58, or 0.01 ≤ c ≤ 0.55. In the above Chemical Formula 2, d represents the doping element (M) among the metals excluding lithium in the positive electrode active material. 1 It represents the molar ratio of ), which can be 0≤d≤0.2, 0≤d≤0.18, or 0≤d≤0.15.

[0062] For example, the positive active material particles prepared in this step may include a first positive active material particle having an average particle size (D50) of 10 to 20 μm; and a second positive active material particle having an average particle size (D50) of 1 to 10 μm. By including the first positive active material particle and the second positive active material particle having different average particle sizes (D50), the particle size distribution of the positive active material particles may have a bimodal distribution. By including the positive active material particles having the bimodal distribution, the lithium secondary battery containing the manufactured positive active material composite may have a more significant energy density.

[0063] For example, the average particle size (D50) of the first positive active material particle may be 10 to 20 μm, specifically 10.5 to 18 μm, more specifically 11 to 16 μm, and the average particle size (D50) of the second positive active material particle may be 1 to 10 μm, specifically 1.5 to 8 μm, more specifically 2 to 6 μm.

[0064] For example, the weight ratio of the first positive active material particle and the second positive active material particle may be 1:0.1 to 0.5, specifically 1:0.12 to 0.45, more specifically 1:0.15 to 0.4. When the weight ratio of the first positive active material particle and the second positive active material particle satisfies the above range, the dispersibility of the manufactured positive active material composite and the wettability of the electrolyte at the positive electrode may be improved.

[0065] For example, in the step of obtaining a coating composition, the ionic material may be represented by the following chemical formula 3 or chemical formula 4.

[0066] [Chemical Formula 3]

[0067]

[0068] [Chemical Formula 4]

[0069]

[0070] In the above chemical formulas 3 and 4, R2 is a substituted or unsubstituted (C1-C10) hydrocarbon group, X is N(CF3SO2)2, N(FSO2)2, or CF3SO3, L1 is each independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, L2 is (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, and the hydrogens of L1 and L2 can each be independently substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.

[0071] The substituted or unsubstituted (C1-C10) hydrocarbon group of the above R2 may include a linear or branched (C1-C10) alkyl, a (C3-C10) cycloalkyl group, a (C3-C10) cycloalkenylene group, or a combination thereof, and the methylene group of the substituent may be substituted with one or more substituents selected from the group consisting of -O-, -OC(O)-, -OC(O)O-, -NHCO-, and -NHC(O)O-. Specifically, the above R2 may be a linear or branched (C1-C10) alkyl or a (C3-C10) cycloalkyl group, and more specifically, may be a linear or branched (C1-C8) alkyl, a linear or branched (C1-C6) alkyl, or a linear or branched (C1-C4) alkyl.

[0072] In the above chemical formulas 3 and 4, L1 may each independently be a direct bond or a (C1-C6)alkylene. Additionally, L2 may be a (C1-C6)alkylene, specifically a (C1-C4)alkylene.

[0073] As a specific example, in the above chemical formulas 3 and 4, R2 is (C1-C4)alkyl, X is N(CF3SO2)2, N(FSO2)2 or CF3SO3, L1 is a direct bond, and L2 may be (C2-C6)alkylene.

[0074] For example, in the step of obtaining a coating composition, an ionic substance represented by Formula 3 or Formula 4 can be prepared through a counter-ion exchange reaction of a compound represented by Formula 5 or Formula 6 below, respectively. In Formula 5 below, R2 and L1 can be described as identical to R2 and L1 of Formula 3, and in Formula 6, L1 and L2 can be described as identical to L1 and L2 of Formula 4, and in Formulas 5 and 6, Y can mean a halogen.

[0075] [Chemical Formula 5]

[0076]

[0077] [Chemical Formula 6]

[0078]

[0079] For example, an ionic substance can be prepared by reacting a compound represented by Chemical Formula 5 (or a compound represented by Chemical Formula 6) with a lithium salt (LiX, where X is N(CF3SO2)2, N(FSO2)2, or CF3SO3). In this case, the reaction between the compound represented by Chemical Formula 5 (or a compound represented by Chemical Formula 6) and the lithium salt can be carried out in a molar ratio of 1:0.5 to 5.0, specifically 1:1.0 to 4.0, more specifically 1:1.0 to 3.0.

[0080] For example, in the step of obtaining a coating composition, the initiator may include a photoinitiator or a thermal initiator, and specifically, may include an azo compound as the thermal initiator. For example, the azo compound is not particularly limited as long as it is a material conventionally used as an initiator, and specific examples may include azobis(isobutyronitrile) or azobis(2,4-dimethylvaleronitrile).

[0081] For example, in the step of obtaining a coating composition, the coating composition may further include a compound containing an acrylate group. In this case, the cathode active material composite produced has improved dispersibility and electrolyte wettability at the cathode as described above, and at the same time, the cathode for a secondary battery and the lithium secondary battery containing the cathode active material composite can be realized with high power and high capacity.

[0082] For example, the above compound may include two or more acrylate groups, specifically three or more. For example, the above compound may include one or more selected from the group consisting of ethoxylated trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tris(3-mercaptopropionate), and dipentaerythritol penta(meth)acrylate, and specifically may include ethoxylated trimethylolpropane tri(meth)acrylate.

[0083] For example, in the step of obtaining a coating composition, the ionic material and the compound containing acrylate groups may be mixed in a weight ratio of 1:0.05 to 0.3, specifically 1:0.05 to 0.25, and more specifically 1:0.05 to 0.2. When the weight ratio of the ionic material and the compound containing acrylate groups satisfies the above range, a more uniform coating layer may be formed on the surface of the positive active material particles in the process described below.

[0084] In the step of manufacturing the cathode active material composite, mixing can be performed by stirring at a speed of 1500 rpm or higher. In this case, as frictional heat is generated while mixing the cathode active material particles and the coating composition at a high speed, a cross-linking reaction of the raw materials included in the coating composition is performed, and finally, a uniform coating layer can be formed on the surface of the cathode active material particles. For example, the mixing speed may be 1500 to 5000 rpm, specifically 1500 to 4500 rpm, and more specifically 1500 to 4000 rpm.

[0085] For example, the above mixing may be performed under solvent-free conditions where the solvent is substantially absent. “Meaning that the solvent is substantially absent” may mean that the solvent is included in an amount of 20 parts by weight or less, 10 parts by weight or less, or 1 part by weight or less per 100 parts by weight of a polymerizable composition comprising an ionic substance and a compound containing an acrylate group. The above mixing may be performed in a reactor in which a polymerization reaction by an initiator can be performed, and the reactor may contain conventional stirring means such as a paddle blade, ribbon blade, gate blade, turbine blade propeller, impeller, or screw stirrer.

[0086] The above-mentioned positive active material particles, ionic material, and initiator may be loaded into the internal space of the reactor, and a polymerization reaction by the initiator may be initiated along with stirring to carry out a coating process. It may be preferable for the internal space of the reactor to be filled with an inert gas.

[0087] For example, the positive electrode active material particles and the coating composition may be mixed in a weight ratio of 1:0.001 to 0.06, 1:0.002 to 0.04, 1:0.002 to 0.02, or 1:0.003 to 0.01, more specifically in a weight ratio of 1:0.004 to 0.008. When the weight ratio of the positive electrode active material particles and the coating composition satisfies the above range, the dispersibility of the positive electrode active material composite being manufactured can be improved.

[0088] For example, prior to the step of manufacturing the positive electrode active material composite, the method may further include a step of heat-treating the coating composition at a temperature of 30 to 150°C. For example, the heat-treatment temperature may be 40 to 130°C, and more specifically, 50 to 100°C.

[0089] According to one embodiment of the present invention, a positive electrode active material composite is provided. The positive electrode active material composite according to one embodiment of the present invention can be manufactured using the aforementioned manufacturing method.

[0090] The cathode active material composite manufactured by the above-described method exhibits excellent dispersibility in the cathode as the coating layer containing a polymer is composited with the cathode active material particles. In addition, the cathode containing the cathode active material composite can have rapid electrolyte wettability as the affinity of the cathode is enhanced by the coating layer of the cathode active material composite. Accordingly, the lithium secondary battery containing the cathode active material composite can maintain a smooth flow of lithium ions and can have excellent ion conductivity, lifespan characteristics, and charge / discharge efficiency at high temperatures.

[0091] The positive electrode active material composite comprises positive electrode active material particles comprising a lithium composite oxide; and a coating layer located on the surface of the positive electrode active material particles, wherein the coating layer comprises a polymer comprising a first repeating unit derived from an ionic material represented by the following chemical formula 1.

[0092] [Chemical Formula 1]

[0093]

[0094] In the above Chemical Formula 1, R1 is a substituted or unsubstituted (C1-C10) hydrocarbon group of n, n is an integer from 1 to 3, X is N(CF3SO2)2, N(FSO2)2, or CF3SO3, and L1 is each independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, and the hydrogen of L1 may each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy. A specific description of Chemical Formula 1 can be described in the same way as described above in the method for manufacturing the cathode active material composite.

[0095] The positive electrode active material particles comprise a lithium composite oxide, and the lithium composite oxide may use a compound capable of reversibly intercalating and deintercalating lithium (a lithated intercalation compound). The positive electrode active material particles can be described in the same manner as previously described in the method for manufacturing the positive electrode active material composite.

[0096] For example, the weight ratio of the first positive active material particle and the second positive active material particle may be 1:0.1 to 0.5, specifically 1:0.12 to 0.45, more specifically 1:0.15 to 0.4. When the weight ratio of the first positive active material particle and the second positive active material particle satisfies the above range, the dispersibility of the positive active material composite and the wettability of the electrolyte at the positive electrode may be improved.

[0097] For example, the positive active material particles may be included in an amount of 70 to 99 weight%, 80 to 99 weight%, or 85 to 99 weight% with respect to the total weight of the positive active material composite.

[0098] For example, an ionic substance can be represented by the following chemical formula 3 or chemical formula 4.

[0099] [Chemical Formula 3]

[0100]

[0101] [Chemical Formula 4]

[0102]

[0103] In the above chemical formulas 3 and 4, R2 is a substituted or unsubstituted (C1-C10) hydrocarbon group, X is N(CF3SO2)2, N(FSO2)2, or CF3SO3, L1 is independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, L2 is (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, and the hydrogens of L1 and L2 may each be independently substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy. The specific description of chemical formulas 3 and 4 can be described in the same way as described above in the method for manufacturing the cathode active material composite.

[0104] For example, the polymer included in the coating layer may further include a second repeating unit derived from a compound containing an acrylate group. When the second repeating unit is included, the aforementioned dispersibility and electrolyte wettability at the anode are improved, and at the same time, it may be possible to realize a cathode for a secondary battery and a lithium secondary battery having high power and high capacity. A compound containing an acrylate group can be described in the same way as described above in the method for manufacturing a cathode active material composite.

[0105] For example, the molar ratio of the first repeating unit and the second repeating unit is not particularly limited, and by appropriately considering the number of functional groups of the monomer from which the first repeating unit and the second repeating unit are derived, the polymer may include the first repeating unit and the second repeating unit in a molar ratio of 1:0.01 to 0.5, specifically 1:0.05 to 0.35, and more specifically 1:0.08 to 0.25. When the molar ratio of the first repeating unit and the second repeating unit satisfies the above range, the dispersibility of the anode active material composite and the wettability of the electrolyte at the anode may be improved.

[0106] For example, the coating layer may be included in an amount of 0.1 to 5.0 wt%, 0.1 to 4.0 wt%, 0.1 to 3.0 wt%, or 0.1 to 2.0 wt%, more specifically 0.35 to 0.75 wt% based on the total weight of the positive active material composite. For another example, the thickness of the coating layer may be 0.001 to 0.1 μm, 0.005 to 0.05 μm, or 0.01 to 0.03 μm. When the content and / or thickness of the coating layer each satisfy the above ranges, the dispersibility of the positive active material composite can be secured at an excellent level without excessive reduction in electron transport resistance.

[0107] The present invention will be described in detail below through examples. However, it should be noted that the examples described below are intended merely to illustrate and embody the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the patent claims and matters reasonably inferred therefrom.

[0108] (Example 1)

[0109] (1) Preparation of a positive electrode active material complex

[0110] (Preparation of positive electrode active material particles) LiNi with an average particle size (D50) of 13.5 µm 0.9 Mn 0.07 Co 0.03 First cathode active material particles of O2 and LiNi having an average particle size (D50) of 4.3㎛ 0.94 Mn 0.04 Co 0.02 The second positive active material particles of O2 were mixed in a weight ratio of 80:20 to prepare the positive active material particles.

[0111] (Obtaining a coating composition) 90% by weight of 3-Ethyl-1-vinyl-1H-imidazol-3-ium bis(trifluoromethanesulfonyl)imide (EVImTFSI), an ionic substance represented by the following chemical formula 3 (R2=ethyl, L1=direct bond, X=N(CF3SO2)2), and 10% by weight of ethoxylated trimethylolpropane triacrylate were mixed, and then azobisisobutyronitrile (1 part by weight of initiator per 100 parts by weight of ethoxylated trimethylolpropane triacrylate) was added as an initiator.

[0112] [Chemical Formula 3]

[0113]

[0114] (Preparation of positive electrode active material composite) Positive electrode active material particles and a coating composition were mixed in a weight ratio of 99.7:0.3, mixed using a self-rotating mixer at 2000 rpm for 3 minutes, and then naturally cooled to prepare a positive electrode active material composite.

[0115] (2) Manufacturing of the anode

[0116] A cathode material was prepared by mixing 96.5 wt% of the cathode active material composite prepared in (1), 1.5 wt% of carbon black (Super-P, average particle size: 40 nm) as a conductive material, and 2 wt% of polyvinylidene fluoride as a binder. A cathode slurry was prepared by adding the cathode material to an N-methyl-2-pyrrolidone solvent so that the cathode material constituted 65 wt%. The cathode slurry was applied to an aluminum thin film with a thickness of 20 μm using a doctor blade, hot-air dried at 100°C, vacuum dried at 130°C for 24 hours, and rolled with a roll press to produce a cathode containing a 45 μm thick cathode active material layer. At this time, the cathode active material loading amount of the cathode was 3.5 mAh / cm² 2 It was, and the density of the mixture was 3.6 g / cc.

[0117] (3) Manufacturing of lithium secondary batteries

[0118] A battery assembly was manufactured by laminating the positive electrode, negative electrode (a negative electrode with a thickness of 100 μm attached to a copper thin film with a thickness of 20 μm), and separator (thickness: 13 μm, SC13-D4-BP, Gellec) manufactured in (2). An aluminum battery tab (0.1 T x 7 mm) was ultrasonically welded to the unbuilt part of the positive electrode assembly, and a nickel battery tab (0.1 T x 7 mm) was welded to the unbuilt part of the negative electrode assembly. Then, the assembly was placed into a battery pouch film (153 μm, DNP) formed to fit the battery assembly and sealed. Subsequently, a lithium secondary battery was manufactured by injecting 2.5 g / Ah of a liquid electrolyte containing 1 mole of LiPF6 dissolved in a solvent mixed with ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1.

[0119] (Example 2)

[0120] In the preparation of the positive active material composite of Example 1, the positive active material particles and the coating composition were mixed using a co-rotating mixer in the (preparation of positive active material composite) step, and additionally, the mixture was heat-treated at a temperature of 70°C for 1 hour and then naturally cooled. Except for these steps, the positive active material composite, the positive electrode, and the lithium secondary battery were prepared in the same manner as in Example 1.

[0121] (Example 3)

[0122] A positive electrode active material composite, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1, except that in the step of preparing the positive electrode active material composite of Example 1 (obtaining the coating composition), the ionic material was 3,3'-(Butane-1,4-diyl)bis(1-vinyl-3-imidazolium) Bis(trifluoromethanesulfonyl)imide (BVImTFSI2), which is represented by the following chemical formula 4 (L1=direct bonding, L2=butylene, X=N(CF3SO2)2).

[0123] [Chemical Formula 4]

[0124]

[0125] (Example 4)

[0126] In the preparation of the positive active material composite of Example 3, the positive active material particles and the coating composition were mixed in a weight ratio of 99.2:0.8 in the step (preparation of positive active material composite), and the positive active material composite, positive and secondary batteries were prepared in the same manner as in Example 3.

[0127] (Comparative Example 1)

[0128] (1) Preparation of positive active material particles

[0129] LiNi with an average particle size (D50) of 13.5㎛ 0.9 Mn 0.07 Co 0.03 First cathode active material particles of O2 and LiNi having an average particle size (D50) of 4.3㎛ 0.94 Mn 0.04 Co 0.02 The second positive active material particles of O2 were mixed in a weight ratio of 80:20 to prepare the positive active material particles.

[0130] (2) Manufacturing of positive electrodes and lithium secondary batteries

[0131] Using the positive active material particles prepared in (1), a positive electrode and a lithium secondary battery were manufactured in the same manner as in Example 1.

[0132] (Comparative Example 2)

[0133] A positive electrode active material composite, a positive electrode, and a lithium secondary battery were prepared in the same manner as in Example 1, except that in the step of preparing the positive electrode active material composite of Example 1, the coating composition was obtained without adding an initiator (azobi-sisobutyronitrile) (obtaining the coating composition).

[0134] (Experimental Example 1: FT-IR Analysis)

[0135] For the cathode active material composite of Example 1 and the cathode active material particles of Comparative Example 1, the formation of a coating layer on the cathode active material composite was confirmed through FT-IR analysis (equipment name: ALPHA II FT-IR Base Spectrometer, manufacturer: Bruker), and the results are shown in FIG. 1.

[0136] Referring to Fig. 1, in the case of Example 1, unlike Comparative Example 1, peaks of bonds (CF bonds, SN bonds, SO bonds) derived from the coating composition were observed, and it can be confirmed that a coating layer was formed on the surface of the positive active material particles.

[0137] (Experimental Example 2: Electrochemical Evaluation of Lithium Secondary Battery)

[0138] For the lithium secondary batteries of the above examples and comparative examples, the capacity realization rate with respect to initial efficiency and discharge rate was evaluated using the following evaluation method.

[0139] (1) Initial efficiency

[0140] A lithium secondary battery was charged to 4.3V at a C-rate of 0.1 under constant current / constant voltage (CC / CV) conditions at 25℃ and then cut off. Subsequently, it was discharged to 3.0V at a C-rate of 0.1 (CC conditions). The percentage of the discharge capacity divided by the charge capacity was calculated as the initial efficiency, and the results are shown in Table 1.

[0141] (2) Capacity realization rate (output characteristics) relative to discharge rate

[0142] A lithium secondary battery was charged to 4.3V at a C-rate of 0.2 under constant current / constant voltage (CC / CV) conditions at 25°C and then cut off. Subsequently, it was discharged (CC conditions) to 3.0V at different discharge rates of 0.2, 0.33, 0.5, 1.0, 2.0, 3.0, and 5.0 C-rates. The capacity realization rate for each discharge rate was calculated by dividing the discharge capacity for each discharge rate by the initial discharge capacity to determine the percentage, and the results are shown in Figure 2. At this time, the initial discharge capacity was obtained by charging the lithium secondary battery to 4.3V at a C-rate of 0.2 under the above constant current / constant voltage conditions, cutting it off, and then discharging it to 3.0V at a C-rate of 0.2.

[0143] Classification Initial Efficiency (%) Example 191.1 Example 290.9 Example 391.4 Example 490.8 Comparative Example 189.7 Comparative Example 272.4

[0144] Referring to Table 1 and Figure 2, Examples 1 to 4 showed higher initial efficiency and capacity realization rate (output characteristics) at a discharge rate of 3.0 C-rate or higher than Comparative Examples 1 and 2. Specifically, since Comparative Example 2 did not contain an initiator, the cross-linking reaction of the raw material included in the coating composition was not performed, and thus the battery performance was reduced.

[0145] In addition, in the case of Example 1, even though no additional heat treatment was performed during the manufacturing step of the cathode active material composite, the initial efficiency and capacity realization rate at a discharge rate of 3.0 C-rate or higher were similar to those of Example 2. That is, it was confirmed that the cross-linking reaction of the raw materials included in the coating composition was effectively carried out because frictional heat is generated by mixing using a self-rotating mixer.

[0146] The above embodiments are merely examples, and the present invention is not limited thereto. Any configuration having substantially the same structure as the technical concept described in the claims of the present invention and achieving the same functional effect is included within the technical scope of the present invention.

Claims

1. A step of preparing positive electrode active material particles containing a lithium composite oxide; A step of obtaining a coating composition by mixing an ionic substance represented by the following chemical formula 1 and an initiator; and A method for manufacturing an anode active material composite, comprising the step of mixing the anode active material particles and the coating composition to manufacture an anode active material composite. [Chemical Formula 1] (In the above Chemical Formula 1, R1 is a substituted or unsubstituted (C1-C10) hydrocarbon group with n, n is an integer from 1 to 3, X is N(CF3SO2)2, N(FSO2)2 or CF3SO3, L1 is each independently a direct bond, (C1-C8)alkylene, (C1-C8)alkenylene or a combination thereof, and the hydrogen of L1 may each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.) 2. In Paragraph 1, A method for manufacturing a positive electrode active material composite, wherein, in the step of manufacturing the positive electrode active material composite, the mixing is performed by stirring at a speed of 1500 rpm or more.

3. In Paragraph 1, A method for preparing an anode active material composite, wherein, in the step of obtaining the above coating composition, the coating composition further comprises a compound containing an acrylate group.

4. In Paragraph 3, A method for manufacturing a positive electrode active material composite, wherein the above compound comprises three or more acrylate groups.

5. In Paragraph 3, A method for preparing an anode active material composite, wherein the above ionic material and the above compound containing acrylate groups are mixed in a weight ratio of 1:0.05 to 0.

3.

6. In Paragraph 1, A method for manufacturing a positive electrode active material composite, wherein the positive electrode active material particles and the coating composition are mixed in a weight ratio of 1:0.001 to 0.

06.

7. In Paragraph 1, A method for manufacturing a positive electrode active material complex comprising an azo compound, wherein the above-mentioned initiator is a compound.

8. In Paragraph 1, A method for manufacturing a positive electrode active material composite, wherein the positive electrode active material particles comprise one or more of a single-crystal active material and a polycrystalline active material.

9. In Paragraph 1, A method for manufacturing a positive electrode active material complex, wherein the positive electrode active material particles comprise a positive electrode active material represented by the following chemical formula 2. [Chemical Formula 2] Li x [Ni a Co b Mr c M 1 d ]O2 (In the above chemical formula 2, M 1 ...is one or more selected from Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, P, Y, Na, and Ca, and 0.8≤x≤1.3, 0.5≤a≤1.0, 0≤b≤0.5, 0≤c≤0.5, 0≤d≤0.2, and a+b+c+d=1.) 10. In Paragraph 1, A method for manufacturing a positive active material composite, wherein the positive active material particles comprise a first positive active material particle having an average particle size (D50) of 10 to 20 μm; and a second positive active material particle having an average particle size (D50) of 1 to 10 μm.

11. In Paragraph 10, A method for manufacturing a positive electrode active material composite, wherein the weight ratio of the first positive electrode active material particle and the second positive electrode active material particle is 1:0.1 to 0.

5.

12. In Paragraph 1, A method for preparing an anode active material complex, wherein the above ionic material is represented by the following chemical formula 3 or chemical formula 4. [Chemical Formula 3] [Chemical Formula 4] (In the above chemical formulas 3 and 4, R2 is a substituted or unsubstituted (C1-C10) hydrocarbon group, X is N(CF3SO2)2, N(FSO2)2, or CF3SO3, L1 is each independently a directly bonded (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, L2 is (C1-C8)alkylene, (C1-C8)alkenylene, or a combination thereof, and the hydrogens of L1 and L2 may each independently be substituted with one or more substituents selected from halogen, nitro, cyano, and (C1-C7)alkoxy.) 13. In Paragraph 1, A method for manufacturing an anode active material composite, further comprising the step of heat-treating the coating composition at a temperature of 30 to 150°C prior to the step of manufacturing the anode active material composite.

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