Method for producing a positive electrode slurry composition and method for producing a positive electrode

Abstract

The present invention comprises the steps of (S1) adding a positive electrode active material, a conductive material, a binder, and a non-aqueous solvent to a mixer and mixing to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C, (S2) cooling the mixture to -30°C to 15°C to produce a positive electrode slurry composition precursor, and (S3) maintaining the temperature of the positive electrode slurry composition precursor, V 72 The step of producing a positive electrode slurry composition in which is 0% or more and 50% or less, and the V n This relates to a method for producing a positive electrode slurry composition and a method for producing a positive electrode, where the viscosity increase rate is expressed by mathematical formula 1 described herein.

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2023-0070277 dated May 31, 2023, and all content disclosed in the said Korean Patent Application is incorporated herein by reference.

[0002] The present invention relates to a method for producing a positive electrode slurry composition and a method for producing a positive electrode. [Background technology]

[0003] As the development and demand for mobile device technologies increase, the demand for rechargeable batteries as an energy source is rapidly growing. Among these rechargeable batteries, lithium-ion batteries, which have high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0004] Lithium transition metal composite oxides are used as the positive electrode active material for lithium secondary batteries, and among them, lithium cobalt composite metal oxides such as LiCoO2, which have a high operating voltage and excellent capacity characteristics, are mainly used. However, LiCoO2 has poor thermal properties due to the destabilization of its crystal structure by delithiation. In addition, LiCoO2 is expensive, which limits its use in large quantities as a power source in fields such as electric vehicles.

[0005] As alternatives to the aforementioned LiCoO2, materials such as lithium manganese composite metal oxides (LiMnO2 or LiMn2O4, etc.), lithium iron phosphate compounds (LiFePO4, etc.), and lithium nickel composite metal oxides (LiNiO2, etc.) have been developed. Among these, research and development on lithium nickel composite metal oxides, which have a high reversible capacity of approximately 200 mAh / g and facilitate the realization of high-capacity batteries, are being pursued more actively. However, LiNiO2 has inferior thermal stability compared to LiCoO2, and if an internal short circuit occurs due to external pressure while charged, the positive electrode active material itself decomposes, causing the battery to rupture and ignite. Therefore, as a method to maintain the excellent reversible capacity of LiNiO2 while improving its low thermal stability, lithium transition metal oxides in which some of the Ni is replaced with Co, Mn, and Al have been developed.

[0006] Lithium nickel composite metal oxides and lithium transition metal oxides containing a large amount of nickel may retain a relatively large amount of lithium oxide as an impurity during the manufacturing process. This impurity can be converted into LiOH and Li2CO3, which can cause gelation during the manufacturing process of the cathode slurry and the process of manufacturing the cathode using the manufactured cathode slurry. When the cathode slurry gels, its viscosity increases, which can cause problems in the cathode manufacturing process, and consequently, significant costs and efforts are required to control the process.

[0007] Furthermore, increasing the solid content of the positive electrode slurry has effects such as increased productivity, improved electrode drying efficiency, and improved binder migration. However, a higher solid content leads to higher viscosity, and the viscosity of the manufactured positive electrode slurry increases rapidly with storage time. When the viscosity of the positive electrode slurry increases so drastically, quality problems may arise with the positive electrodes manufactured using it, and the positive electrode slurry itself may become difficult to use in the manufacture of positive electrodes.

[0008] Therefore, there is a need to develop a method that can suppress the increase in viscosity over time after the production of a positive electrode slurry with a high solid content. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2007-141649 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a method for producing a positive electrode slurry composition that can suppress the increase in viscosity of a positive electrode slurry composition having a solid content of more than 60%.

[0011] Another objective of the present invention is to provide a method for manufacturing a cathode using a cathode slurry composition in which the viscosity increase is controlled. [Means for solving the problem]

[0012] To solve the above problems, the present invention provides a method for producing a positive electrode slurry composition and a method for producing a positive electrode.

[0013] (1) The present invention comprises the steps of (S1) putting a positive electrode active material, a conductive material, a binder and a non-aqueous solvent into a mixer and mixing them to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C or higher and 45°C or lower, (S2) cooling the mixture to -30°C or higher and 15°C or lower to produce a positive electrode slurry composition precursor, and (S3) maintaining the temperature of the positive electrode slurry composition precursor, V 72 The step of producing a positive electrode slurry composition in which is 0% or more and 50% or less, and the V n This provides a method for producing a positive electrode slurry composition, where the viscosity increase rate is expressed by the following mathematical formula 1, and the viscosity increase rate is the viscosity increase rate when the temperature of the positive electrode slurry composition precursor is maintained for n hours. [Mathematical formula 1] Viscosity increase rate (V n [%])=(VS2[cP]-VS1[cP]×100 / VS1[cP]) In the above Mathematical Formula 1, VS1 is the viscosity [cP] of the mixture, and VS2 is the viscosity [cP] of the positive electrode slurry composition.

[0014] (2) The present invention provides a method for producing a positive electrode slurry composition in which, in the above (1), the mixer has a surface temperature of -30°C or higher and 20°C or lower.

[0015] (3) The present invention provides a method for producing a positive electrode slurry composition in which, in the above (1) or (2), the mixer includes a mixing chamber, and the temperature of the inner surface and the inner space of the mixing chamber are each independently -30°C or higher and 20°C or lower.

[0016] (4) The present invention provides a method for producing a positive electrode slurry composition in which, in any one of the above (1) to (3), the positive electrode active material includes one or more selected from lithium composite transition metal compounds having a composition represented by the following Chemical Formulas 1 to 4. [Chemical Formula 1] Li a [Ni b Co c Mn d M 1 1-(b+c+d) O2 In the above Chemical Formula 1, M 1 is one or more selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi, 0.9 ≦ a ≦ 1.1, 0 < b < 1, 0 < c < 1, 0 < d < 1, and 0 < b + c + d ≦ 1, [Chemical Formula 2] Li e Ni 1-f M 2 f O2 In the above Chemical Formula 2, M 2is one or more elements selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ e ≤ 1.1 and 0 ≤ f < 1, [Chemical formula 3] Li g Ni h Mn i M 3 j O2 In the aforementioned chemical formula 3, M 3 is one or more elements selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, B, and Bi. 1.0≦g≦1.5, 0≦h≦0.5, 0.4≦i≦0.9, 0≦j≦0.1, [Chemical formula 4] LiFe 1-k M 4 k PO4 In the aforementioned chemical formula 4, M 4 This is one or more elements selected from the group consisting of Mn, Co, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Te, Ir, Gd, Sm, Sb, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0 ≤ k < 1.

[0017] (5) The present invention provides a method for producing a positive electrode slurry composition in any one of (1) to (4) above, wherein the positive electrode active material comprises two or more lithium composite transition metal compounds selected from those having compositions represented by the following chemical formulas 1 to 4. [Chemical formula 1] Li a [Ni b Co c Mn d M 11-(b+c+d) ]O2 In the aforementioned chemical formula 1, M 1 is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ a ≤ 1.1, 0 <b<1、0<c<1、0<d<1、0<b+c+d≦1であり、 [Chemical formula 2] Li e Ni 1-f M 2 f O2 In the aforementioned chemical formula 2, M 2 is one or more elements selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ e ≤ 1.1 and 0 ≤ f < 1, [Chemical formula 3] Li g Ni h Mn i M 3 j O2 In the aforementioned chemical formula 3, M 3 is one or more elements selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, B, and Bi. 1.0≦g≦1.5, 0≦h≦0.5, 0.4≦i≦0.9, 0≦j≦0.1, [Chemical formula 4] LiFe 1-k M 4 k PO4 In the aforementioned chemical formula 4, M 4This is one or more elements selected from the group consisting of Mn, Co, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Te, Ir, Gd, Sm, Sb, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0 ≤ k < 1.

[0018] (6) The present invention provides a method for producing a positive electrode slurry composition in any one of (1) to (5) above, wherein the positive electrode active material comprises a lithium composite transition metal compound having a composition represented by the following chemical formula 5. [Chemical formula 5] Li a’ [Ni b’ Co c’ Mn d’ M 5 1-(b’+c’+d’) ]O2 M 5 is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9≦a'≦1.1, 0.6≦b'<1, 0 <c’<0.4、0<d’<0.4、0<b’+c’+d’≦1である。

[0019] (7) The present invention provides a method for producing a positive electrode slurry composition in any one of the above (1) to (6), wherein the mixing is carried out such that, based on 100 parts by weight of solids, the positive electrode active material is 85 parts by weight or more and 99 parts by weight or less, the conductive material is 0.5 parts by weight or more and 10 parts by weight or less, and the binder is 0.5 parts by weight or more and 10 parts by weight or less.

[0020] (8) The present invention provides a method for producing a positive electrode slurry composition in any one of (1) to (7) above, wherein the solid content is 70% by weight or more and 85% by weight or less.

[0021] (9) The present invention provides a method for producing a cathode slurry composition precursor, wherein in any one of (1) to (8) above, (S2) is a method for producing a cathode slurry composition precursor by cooling the mixture to a temperature of -30°C or higher and -23°C or lower.

[0022] (10) In any one of the above (1) to (9), V 24 The present invention provides a method for producing a positive electrode slurry composition in which the concentration is between -5% and 30%.

[0023] (11) In any one of the above (1) to (10), V 168 The present invention provides a method for producing a positive electrode slurry composition in which the content is 0% or more and 80% or less.

[0024] (12) In any one of the above (1) to (11), V 336 The present invention provides a method for producing a positive electrode slurry composition in which the content is 1% or more and 120% or less.

[0025] (13) The present invention provides a method for producing a cathode slurry composition in which, in any one of (1) to (12) above, the mixture, the cathode slurry composition precursor, and the cathode slurry composition each independently have a viscosity of 20,000 cP or less.

[0026] (14) The present invention provides a method for producing a positive electrode, comprising the steps of (1) to (13) above, producing a positive electrode slurry composition, and (B) applying and drying the positive electrode slurry composition onto a current collector to form a positive electrode active material layer.

[0027] (15) The present invention provides a method for manufacturing a positive electrode, wherein, in (14), immediately before step (B), a step (A1) is added in which the positive electrode slurry composition is transferred to a means for coating a positive electrode active material composition, and the transfer is carried out at a temperature of -30°C or higher and 15°C or lower. [Effects of the Invention]

[0028] The method for producing a positive electrode slurry composition according to the present invention includes the steps of: mixing a positive electrode active material, a conductive material, and a binder in a non-aqueous solvent to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C; and cooling the mixture to a temperature of -30°C to 15°C to produce a positive electrode slurry composition precursor. This method has the effect of improving the viscosity of a positive electrode slurry composition with a high solid content, thereby improving problems in the manufacturing process of positive electrodes. [Modes for carrying out the invention]

[0029] The present invention will be described in more detail below to aid in understanding the present invention.

[0030] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0031] In this specification, terms such as “includes,” “equip,” or “have” are intended to specify the presence of implemented features, figures, steps, components, or combinations thereof, and should be understood not to preemptively exclude the existence or possibility of adding one or more other features, figures, steps, components, or combinations thereof.

[0032] In this specification, the content of each element in a lithium complex transition metal compound may be measured by ICP (Inductive Coupled Plasma) analysis using an inductively coupled plasma emission spectrometer (ICP-OES; PerkinElmer Optima 8000DV).

[0033] Method for producing a positive electrode slurry composition The method for producing the positive electrode slurry composition according to the present invention will be described below.

[0034] The present invention provides a method for producing a positive electrode slurry composition, which involves preparing the positive electrode slurry composition under predetermined conditions, storing it within a predetermined temperature range, and suppressing the occurrence of gelation of the positive electrode slurry composition.

[0035] Specifically, the method for producing the positive electrode slurry composition of the present invention includes the steps of (S1) adding a positive electrode active material, a conductive material, a binder, and a non-aqueous solvent to a mixer and mixing them to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C, (S2) cooling the mixture to a temperature of -30°C to 15°C to produce a positive electrode slurry composition precursor, and (S3) maintaining the temperature of the positive electrode slurry composition precursor, V 72 The step of producing a positive electrode slurry composition in which is 0% or more and 50% or less, and the V n This is the viscosity increase rate when the temperature of the positive electrode slurry composition precursor is maintained for n hours, and this viscosity increase rate is expressed by the following mathematical formula 1.

[0036] [Mathematical formula 1] Viscosity increase rate (V n [%])=(VS2[cP]-VS1[cP]×100 / VS1[cP])

[0037] In the above mathematical formula 1, VS1 is the viscosity [cP] of the mixture, and VS2 is the viscosity [cP] of the positive electrode slurry composition.

[0038] When the solid content of the positive electrode slurry composition is 60% by weight or less, there is a problem in that the energy density of the manufactured positive electrode is inferior.

[0039] On the other hand, a positive electrode slurry composition prepared by mixing positive electrode active material, conductive material, and binder in a non-aqueous solvent may undergo gelation due to the -OH groups of the components contained in the positive electrode slurry composition and the water they may contain, potentially increasing the viscosity of the positive electrode slurry. When the solid content of the positive electrode slurry exceeds approximately 60% by weight, the viscosity of the positive electrode slurry becomes high, and the viscosity of the positive electrode slurry increases rapidly over time after manufacturing. Thus, when the viscosity of the positive electrode slurry increases and exceeds a predetermined viscosity, there is a problem in forming a uniform positive electrode layer when applying the positive electrode slurry to the substrate. To form a uniform positive electrode layer, it is preferable to use the positive electrode slurry immediately after manufacturing, but in the commercial manufacturing process of positive electrodes, it may be necessary to store the positive electrode slurry for a predetermined period of time after manufacturing, so it is necessary to store the positive electrode slurry and suppress the increase in viscosity.

[0040] As a result of diligent research, the inventors have found that when manufacturing a positive electrode slurry composition, if the manufacturing process includes the steps of adding a positive electrode active material, a conductive material, a binder, and a non-aqueous solvent to a mixer and mixing them to produce a mixture with a solid content of more than 60% by weight and a temperature of -20°C to 45°C, cooling the mixture to a temperature of -30°C to 15°C to produce a positive electrode slurry composition precursor, and maintaining the temperature of the positive electrode slurry composition precursor, the increase in viscosity of the positive electrode slurry composition over time can be suppressed. Furthermore, the inventors have found that even when the solid content of the positive electrode slurry composition is high, the increase in viscosity of the positive electrode slurry composition over time can be suppressed, and the effect of further increasing the solid content in the positive electrode slurry composition can be achieved, thus completing the present invention.

[0041] The positive electrode slurry composition according to the present invention described above can be manufactured by appropriately adjusting the type of positive electrode active material, the type of conductive material, the type of binder, the type of non-aqueous solvent, and the mixing ratio of the solution.

[0042] The steps of the present invention will be described in detail below.

[0043] (S1) Step The process includes the step of (S1) adding a positive electrode active material, a conductive material, a binder, and a non-aqueous solvent to a mixer and mixing them to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C. Specifically, the solid content may be more than 60% by weight, 65% or more by weight, or 70% or more by weight, and may be 75% or less by weight, 80% or less by weight, 85% or less by weight, 90% or less by weight, 95% or less by weight, or less than 100% by weight. When the solid content is 60% by weight or less, the increase in viscosity of the positive electrode slurry composition over time during production is not a major problem, but there is a problem of low energy density of the produced positive electrode. By adjusting the solid content to more than 60% by weight, the energy density of the produced positive electrode can be improved, and in particular, when the solid content is 70% or more by weight and 85% or less by weight, a positive electrode active material with excellent energy density, adjustable viscosity increase rate, and improved coating properties can be produced. Furthermore, the temperature may be -20°C or higher, or -10°C or higher, and may be 10°C or lower, 15°C or lower, 20°C or lower, 25°C or lower, 30°C or lower, 35°C or lower, 40°C or lower, or 45°C or lower. When the temperature of the mixture is within the above range, it can be expected that the gelation of the mixture will be minimized. When the temperature is above 45°C, gelation progresses during mixing, the viscosity of the mixture becomes high, and consequently, there is a problem of high viscosity in the positive electrode slurry composition.

[0044] According to one embodiment of the present invention, the mixer may have a surface temperature of -30°C or higher and 20°C or lower, specifically, a surface temperature of -30°C or higher, -20°C or higher, or -10°C or higher, or 10°C or lower, 15°C or lower, or 20°C or lower.

[0045] Furthermore, the mixer includes a mixing chamber, and the mixing may occur if the temperature of the internal surface and internal space of the mixing chamber are independently -30°C or higher and 20°C or lower. The temperatures of the internal surface and internal space of the mixing chamber may be the same or different, and the temperatures of the internal surface and internal space of the mixing chamber may be -30°C or higher, -20°C or higher, or -10°C or higher, and 10°C or lower, 15°C or lower, or 20°C or lower, respectively. When the surface temperature of the mixer and the temperatures of the internal surface and internal space of the mixing chamber are within the above temperature range, it is possible to prevent the temperature from rising due to the resistance between the mixture and the mixer during mixing, and to produce a mixture with a temperature of -20°C or higher and 45°C or lower. In addition, it can be expected that gelation will not occur during the production of the mixture, and it is even more effective in maintaining a low viscosity for the positive electrode slurry composition.

[0046] The surface temperature of the mixer, the temperature of the inner surface of the mixing chamber, and the temperature of the internal space may be the same. Alternatively, the surface temperature of the mixer, the temperature of the inner surface of the mixing chamber, and the temperature of the internal space may be the same as or lower than the temperature of the mixture.

[0047] According to one embodiment of the present invention, the positive electrode active material may include one or more lithium complex transition metal compounds selected from those having compositions represented by the following chemical formulas 1 to 4.

[0048] [Chemical formula 1] Li a [Ni b Co c Mn d M 1 1-(b+c+d) ]O2

[0049] In the aforementioned chemical formula 1, M 1 is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ a ≤ 1.1, 0 <b<1、0<c<1、0<d<1、0<b+c+d≦1であり、 [Chemical formula 2] Li e Ni 1-f M 2 f O2 In the aforementioned chemical formula 2, M 2 is one or more elements selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ e ≤ 1.1 and 0 ≤ f < 1, [Chemical formula 3] Li g Ni h Mn i M 3 j O2 In the aforementioned chemical formula 3, M 3 is one or more elements selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, B, and Bi. 1.0≦g≦1.5, 0≦h≦0.5, 0.4≦i≦0.9, 0≦j≦0.1, [Chemical formula 4] LiFe 1-k M 4 k PO4 In the aforementioned chemical formula 4, M 4 This is one or more elements selected from the group consisting of Mn, Co, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Te, Ir, Gd, Sm, Sb, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0 ≤ k < 1. In the aforementioned chemical formula 1, Said M 1This is a doping element, specifically, the aforementioned M 1 M is one or more selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 1 While not necessarily included, this can improve capacity characteristics and lifetime characteristics.

[0050] The value of a may be 0.9 or greater, or 1.0 or greater, or 1.1 or less. When a satisfies the above range, high safety and high energy density per unit volume can be achieved.

[0051] The value b is the molar ratio of nickel (Ni) among the total metals excluding lithium in the lithium composite transition metal compound, and may be greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, and may be 0.97 or less, 0.98 or less, 0.99 or less, or less than 1. When b satisfies the above range, high energy characteristics can be achieved.

[0052] The above c is the molar ratio of cobalt (Co) among the total metals excluding lithium in the lithium-compound transition metal compound, and may be greater than 0, 0.01 or more, or 0.02 or more, and may be 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, 0.1 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less, 0.17 or less, 0.18 or less, 0.19 or less, 0.2 or less, 0.21 or less, 0.22 or less, or 0.23 or less. , 0.24 or less, 0.25 or less, 0.26 or less, 0.27 or less, 0.28 or less, 0.29 or less, 0.3 or less, 0.31 or less, 0.32 or less, 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, 0.4 or less, 0.41 or less, 0.42 or less, 0.43 or less, 0.44 or less, 0.45 or less, 0.46 or less, 0.47 or less, 0.48 or less, 0.49 or less, 0.5 or less, 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When c satisfies the above range, stability during the charge-discharge process can be improved and rate characteristics can be enhanced.

[0053] The above d is the molar ratio of manganese (Mn) among the total metals excluding lithium in the lithium-compound transition metal compound, and may be greater than 0, 0.01 or more, or 0.02 or more, and may be 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, 0.1 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less, 0.17 or less, 0.18 or less, 0.19 or less, 0.2 or less, 0.21 or less, 0.22 or less, or 0.23 or less. , 0.24 or less, 0.25 or less, 0.26 or less, 0.27 or less, 0.28 or less, 0.29 or less, 0.3 or less, 0.31 or less, 0.32 or less, 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, 0.4 or less, 0.41 or less, 0.42 or less, 0.43 or less, 0.44 or less, 0.45 or less, 0.46 or less, 0.47 or less, 0.48 or less, 0.49 or less, 0.5 or less, 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When d satisfies the above range, high-temperature stability can be increased and side reactions with the electrolyte can be relatively reduced.

[0054] The above 1-(b+c+d) is the total metal excluding lithium in the lithium composite transition metal compound, M 1 This is the molar ratio of b+c+d. b+c+d may be greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, and may be 0.97 or less, 0.98 or less, 0.99 or less, or 1 or less. When b+c+d satisfies the above range, the stability of the crystal structure of the positive electrode active material is improved and the grain shape can be improved.

[0055] In the aforementioned chemical formula 2, Said M 2 This is a doping element, specifically, the aforementioned M 2 The M is one or more selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi.2 Although not necessarily included, it can improve the capacity characteristics and life characteristics.

[0056] The e may be 0.9 or more, or 1.0 or more, and may also be 1.1 or less. When e satisfies the above range, high safety and high energy density per unit volume can be achieved.

[0057] The 1 - f is the molar ratio of nickel (Ni) among all metals excluding lithium in the lithium composite transition metal compound. The f is the molar ratio of M among all metals excluding lithium in the lithium composite transition metal compound. 2 It may be 0 or more, or 0.01 or more, and may also be 0.1 or less, 0.2 or less, 0.3 or less, 0.4 or less, 0.5 or less, 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When f satisfies the above range, the stability of the crystal structure of the positive electrode active material can be improved, and the particle shape can be improved.

[0058] In the chemical formula 3, The M 3 is a doping element. Specifically, the M 3 is one or more selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. The M 3 Although not necessarily included, it can improve the capacity characteristics and life characteristics.

[0059] The g may be 1.0 or more, 1.1 or more, or 1.2 or more, and may also be 1.3 or less, 1.4 or less, or 1.5 or less. When g satisfies the above range, high safety and high energy density per unit volume can be achieved.

[0060] The h is the molar ratio of nickel (Ni) among the total metals excluding lithium in the lithium composite transition metal compound, and may be 0 or more, 0.1 or more, or 0.2 or more, and may also be 0.3 or less, 0.4 or less, or 0.5 or less. When h satisfies the above range, high energy characteristics can be realized.

[0061] The i is the molar ratio of manganese (Mn) among the total metals excluding lithium in the lithium composite transition metal compound, and may be 0.4 or more, 0.5 or more, or 0.6 or more, and may also be 0.7 or less, 0.8 or less, or 0.9 or less. When i satisfies the above range, the high temperature stability can be increased, and the side reaction with the electrolyte can be relatively reduced.

[0062] The j is the molar ratio of M 3 among the total metals excluding lithium in the lithium composite transition metal compound, and may be 0 or more, or 0.01 or more, and may also be 0.1 or less, 0.2 or less, 0.3 or less, 0.4 or less, 0.5 or less, 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When j satisfies the above range, the stability of the crystal structure of the positive electrode active material can be improved, and the particle shape can be improved.

[0063] The g, h, i, and j may satisfy g + h + i + j = 2.

[0064] In Chemical Formula 4, The M 4 is a doping element. Specifically, the M 4 is one or more selected from the group consisting of Mn, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. The M 4 is not necessarily included, but can improve the capacity characteristics and life characteristics.

[0065] The above 1-k is the molar ratio of Fe among the total metals excluding lithium in the lithium iron phosphate compound. The above k is the molar ratio of M among the total metals excluding lithium in the lithium iron phosphate compound. 4 The molar ratio is 0 or greater, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, or 0.5 or greater, and may be 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When k is within the above range, the particle shape of the positive electrode active material can be improved, the stability of the crystal structure can be improved, the electrical conductivity can be improved, and the capacitance characteristics can be improved.

[0066] According to one embodiment of the present invention, the lithium complex transition metal compound having the composition represented by chemical formula 3 may also be a lithium complex transition metal compound having the composition represented by the following chemical formula 3-1.

[0067] [Chemical formula 3-1] m(Li n Ni o Mn p M 3 q O2)·(1-m)(Li2MnO3)

[0068] In the aforementioned chemical formula 3-1, M 3 is one or more elements selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Mg, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Nb, Cu, In, S, B, and Bi. 0 <m<1、0.9≦n≦1.1、0≦o<1、0<p≦1、0≦q≦0.1である。

[0069] The compound represented by chemical formula 3-1 may also be a compound that simultaneously contains a phase having a crystal structure of the R3-m space group (rhombohedra) and a phase having a crystal structure of the C2 / m space group (monoclinic).

[0070] Said M 3This is a doping element, specifically, the aforementioned M 3 M is one or more selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 3 While not necessarily included, this can improve capacity characteristics and lifetime characteristics.

[0071] The aforementioned m represents the molar ratio of phases having a crystal structure of the R3-m space group (rhombohedra) in the lithium composite transition metal compound, and may be greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, or 0.7 or more, and may be 0.8 or less, 0.9 or less, or less than 1. When m satisfies the above range, high capacity characteristics and high energy density per unit volume can be achieved. The aforementioned 1-m may represent the molar ratio of phases having a crystal structure of the C2 / m space group (monoclinic).

[0072] The aforementioned n is the molar ratio of lithium (Li) in the phase having a rhombohedra crystal structure, and may be 0.9 or greater, 0.95 or greater, or 1.0 or greater, and may also be 1.03 or less, 1.05 or less, 1.07 or less, or 1.1 or less.

[0073] The above o is the molar ratio of nickel (Ni) in a phase having a rhombohedra crystal structure, and may be 0 or greater, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, or 0.5 or greater, and may be 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When o satisfies the above range, a high energy density is observed, and high capacitance characteristics can be achieved.

[0074] The aforementioned p is the molar ratio of manganese (Mn) in a phase having a rhombohedra crystal structure, and may be greater than 0, 0.1 or greater, 0.2 or greater, 0.3 or greater, 0.4 or greater, or 0.5 or greater, and may be 0.6 or less, 0.7 or less, 0.8 or less, 0.9 or less, or 1 or less. When p satisfies the above range, a high energy density is observed, and high capacitance characteristics can be achieved.

[0075] The aforementioned q is M in the phase having the R3-m space group (rhombohedra) crystal structure. 3 The molar ratio of q is 0 or greater, 0.01 or greater, 0.02 or greater, 0.03 or greater, 0.04 or greater, or 0.05 or greater, and may be 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.1 or less. When q satisfies the above range, the stability of the crystal structure of the positive electrode active material is improved, and the grain shape can be improved.

[0076] According to one embodiment of the present invention, the positive electrode active material may contain two or more lithium composite transition metal compounds selected from those having compositions represented by the chemical formulas 1 to 4. In this case, compared to the case in which only one lithium composite transition metal compound is included, the capacity characteristics, lifetime characteristics, rate characteristics, etc., can be improved.

[0077] According to one embodiment of the present invention, the positive electrode active material may include a lithium composite transition metal compound having a composition represented by the following chemical formula 5.

[0078] [Chemical formula 5] Li a’ [Ni b’ Co c’ Mn d’ M 5 1-(b’+c’+d’) ]O2

[0079] M 5is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9≦a'≦1.1, 0.6≦b'<1, 0 <c’<0.4、0<d’<0.4、0<b’+c’+d’≦1である。

[0080] In the aforementioned chemical formula 5, Said M 5 This is a doping element, specifically, the aforementioned M 5 M is one or more selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 5 While not necessarily included, this can improve capacity characteristics and lifetime characteristics.

[0081] The value a' may be 0.9 or greater, 1.0 or greater, or 1.1 or less. When a' satisfies the above range, high safety and high energy density per unit volume can be achieved.

[0082] b' is the molar ratio of nickel (Ni) to the total metals excluding lithium in the lithium-composite transition metal compound, and may be 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, and may be 0.97 or less, 0.98 or less, 0.99 or less, or less than 1. When b' satisfies the above range, high energy characteristics can be achieved.

[0083] The above c' is the molar ratio of cobalt (Co) among the total metals excluding lithium in the lithium composite transition metal compound, and may be greater than 0, 0.01 or more, or 0.02 or more, and may be 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, 0.1 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less. It may also be less than 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, or less than 0.4. When c' satisfies the above range, stability during the charge-discharge process can be improved and rate characteristics can be enhanced.

[0084] The above d' is the molar ratio of manganese (Mn) among the total metals excluding lithium in the lithium-compound transition metal compound, and may be greater than 0, 0.01 or more, or 0.02 or more, and may be 0.03 or less, 0.04 or less, 0.05 or less, 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, 0.1 or less, 0.11 or less, 0.12 or less, 0.13 or less, 0.14 or less, 0.15 or less, 0.16 or less. It may also be 0.17 or less, 0.18 or less, 0.19 or less, 0.2 or less, 0.21 or less, 0.22 or less, 0.23 or less, 0.24 or less, 0.25 or less, 0.26 or less, 0.27 or less, 0.28 or less, 0.29 or less, 0.3 or less, 0.31 or less, 0.32 or less, 0.33 or less, 0.34 or less, 0.35 or less, 0.36 or less, 0.37 or less, 0.38 or less, 0.39 or less, or less than 0.4. When d' satisfies the above range, high-temperature stability can be increased and side reactions with the electrolyte can be relatively reduced.

[0085] The above 1-(b'+c'+d') is the total metal excluding lithium in the lithium composite transition metal compound, M 5This is the molar ratio. The value of b'+c'+d' may be greater than 0, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more, and may be 0.97 or less, 0.98 or less, 0.99 or less, or 1 or less. When the value of b'+c'+d' satisfies the above range, the stability of the crystal structure of the positive electrode active material is improved, and the grain shape can be improved.

[0086] In lithium-rich lithium-transition metal oxides (hereinafter referred to as nickel-rich lithium-transition metal oxides), the nickel content in the total metal excluding lithium among the positive electrode active materials is 60 mol% or more. During the manufacturing process, a relatively large amount of lithium by-products remains on the surface of the lithium-rich lithium-transition metal oxide. Since these impurities are converted to LiOH and Li2CO3, in positive electrode slurry compositions in which nickel-rich lithium-transition metal oxides are applied as the positive electrode active material, the increase in viscosity and the gelation phenomenon may become even more severe. Therefore, in the case of positive electrode slurry compositions using nickel-rich lithium-transition metal oxides, if stored at ambient temperature without taking any other measures, the viscosity increases rapidly over time, and the viscosity increases more rapidly as the temperature rises. For this reason, the present invention can be more effectively applied to the production of positive electrode slurry compositions containing nickel-rich lithium-transition metal oxides, which have a high risk of viscosity increase and gelation.

[0087] On the other hand, the positive electrode active material may optionally further include a coating layer on its surface containing one or more elements selected from the group consisting of Al, Ti, W, B, F, P, Mg, Ni, Co, Fe, Cr, V, Cu, Ca, Zn, Zr, Nb, Mo, Sr, Sb, Bi, Si, Y, and S (hereinafter referred to as "coating elements"). When such a coating layer is included, contact between the positive electrode active material and the electrolyte is blocked, and the generation of gases due to side reactions with the electrolyte and the elution of transition metals can be effectively suppressed.

[0088] The coating layer can be formed by mixing a positive electrode active material with a raw material containing the coating element, and then heat-treating it at a temperature of 200°C to 800°C.

[0089] The conductive material is used to impart conductivity to electrodes and can be used without particular limitations in the battery it is configured in, as long as it does not cause chemical changes and has electronic conductivity. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. Of these, one or more can be used individually or in mixtures of two or more.

[0090] The binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, of which one or more can be used.

[0091] The non-aqueous solvent may be a non-aqueous solvent commonly used in the art, and may be one or more selected from the group consisting of dimethyl sulfoxide (DMSO), DMF (dimethylformamide), isopropyl alcohol, dimethylacetamide, N-methylpyrrolidone (NMP), and acetone.

[0092] The amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into consideration the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that allows for excellent thickness uniformity when applied for the manufacture of the positive electrode.

[0093] The mixture may optionally contain additives as needed.

[0094] According to one embodiment of the present invention, the mixing may be carried out such that, based on 100 parts by weight of solids, the positive electrode active material is 85 parts by weight or more and 99 parts by weight or less, the conductive material is 0.5 parts by weight or more and 10 parts by weight or less, and the binder is 0.5 parts by weight or more and 10 parts by weight or less. Specifically, the mixing may be based on 100 parts by weight of solids, with the positive electrode active material being 85 parts by weight or more, 86 parts by weight or more, 87 parts by weight or more, 88 parts by weight or more, 89 parts by weight or more, or 90 parts by weight or more, and 91 parts by weight or less, 92 parts by weight or less, 93 parts by weight or less, 94 parts by weight or less, 95 parts by weight or less, 96 parts by weight or less, 97 parts by weight or less, 98 parts by weight or less, or 99 parts by weight or less, and the conductive material being 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, or 1 part by weight or more. The amount of the binder may be 2 parts by weight or more, or 3 parts by weight or more, and may be 4 parts by weight or less, 5 parts by weight or less, 6 parts by weight or less, 7 parts by weight or less, 8 parts by weight or less, 9 parts by weight or less, or 10 parts by weight or less. In this case, a positive electrode slurry composition with a high solid content can be effectively produced.

[0095] (S2) Step The process includes step (S1), followed by step (S2), in which the mixture is cooled to a temperature of -30°C or higher and 15°C or lower to produce a cathode slurry composition precursor.

[0096] Specifically, the mixture is cooled to a temperature of -30°C or higher, -23°C or lower, -20°C or lower, -10°C or lower, 0°C or lower, 10°C or lower, or 15°C or lower to produce a cathode slurry composition precursor. When the mixture is cooled within the above temperature range, gelation or an increase in viscosity of the cathode slurry composition can be suppressed. As a result, even after time has passed since the preparation of the cathode slurry composition, the cathode slurry composition can maintain an appropriate viscosity for the formation of the cathode layer. In particular, when the cooling is performed at a temperature of -30°C or higher and -23°C or lower, even if the solid content is high, the viscosity can be kept low and a uniform cathode layer can be formed. When the mixture is cooled to below -30°C, there is a problem that the energy required during cooling is too high, resulting in poor manufacturing efficiency. When the mixture is cooled to above 15°C or not cooled at all, gelation or an increase in viscosity of the cathode slurry composition is not suppressed, and there is a problem that the viscosity increases geometrically over time.

[0097] (S3) Step (S2) After step, maintain the temperature of the positive electrode slurry composition precursor, V 72 The process includes (S3) a step of producing a cathode slurry composition in which the content is 0% or more and 50% or less.

[0098] In this invention, the viscosity increase rate (V n The viscosity increase rate is evaluated (in percentages) and expressed by the parameter shown in the following mathematical formula 1. The viscosity increase rate as used in this invention is a value adjusted according to the viscosity of the positive electrode slurry composition (VS2 [cP]) and the viscosity of the mixture (VS1 [cP]), and the closer the viscosity of the positive electrode slurry composition is to the viscosity of the mixture, the lower the viscosity increase rate.

[0099] [Mathematical formula 1] Viscosity increase rate (V n [%])=(VS2[cP]-VS1[cP]×100 / VS1[cP])

[0100] In the above mathematical formula 1, VS1 is the viscosity [cP] of the mixture, and VS2 is the viscosity [cP] of the positive electrode slurry composition.

[0101] For example, if the viscosity of the positive electrode slurry composition and the viscosity of the mixture are the same, the viscosity increase rate is 0. This means that when a mixture is prepared by mixing the positive electrode active material, conductive material, and binder in a non-aqueous solvent, and the viscosity of the mixture is measured, the viscosity of the positive electrode slurry composition prepared thereafter is measured, and the viscosity does not increase.

[0102] According to the present invention, the temperature of the positive electrode slurry composition precursor is maintained, specifically, V 72 However, the positive electrode slurry composition is produced in a quantity that is 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, or 8% or more, and is 20% or less, 25% or less, 30% or less, 35% or less, 40% or less, 45% or less, or 50% or less. 72 When the viscosity is within the range described above, the increase in viscosity of the positive electrode slurry composition over time is suppressed, and even if the positive electrode slurry composition is not used immediately after production, it can exhibit a viscosity suitable for use in forming the positive electrode layer, and the manufactured positive electrode slurry composition can be stored for a predetermined time. Therefore, since it is not necessary to use the positive electrode slurry composition in the manufacture of the positive electrode immediately after production, flexibility can be provided in the design of the positive electrode manufacturing process. On the other hand, the V 72 If the viscosity exceeds 50%, there is a problem in that it becomes difficult to manufacture a positive electrode with a positive electrode slurry composition that has been stored for a predetermined time or longer, as the viscosity of the positive electrode slurry composition increases over time.

[0103] According to one embodiment of the present invention, V 24 It may be -5% or more and 30% or less. Specifically, the above V 24 This may be -5% or more, -4% or more, -3% or more, -2% or more, or -1% or more, and may be 20% or less, 25% or less, or 30% or less. 24 When the viscosity is within the range described above, the increase in viscosity of the positive electrode slurry composition over time is suppressed, and even if the positive electrode slurry composition is not used immediately after production, it can exhibit a viscosity suitable for use in forming the positive electrode layer, and the manufactured positive electrode slurry composition can be stored for a predetermined period of time.

[0104] According to one embodiment of the present invention, V 168 It may be 0% or more and 80% or less. Specifically, the above V 168 It may be 0% or more, 1% or more, 2% or more, or 3% or more, and may be 55% or less, 60% or less, 65% or less, 70% or less, 75% or less, or 80% or less. The above V 168 When the viscosity is within the range described above, the increase in viscosity of the positive electrode slurry composition over time is suppressed, and even if the positive electrode slurry composition is not used immediately after production, it can exhibit a viscosity suitable for use in forming the positive electrode layer, and the manufactured positive electrode slurry composition can be stored for a predetermined period of time.

[0105] According to one embodiment of the present invention, V 336 This may be 1% or more and 120% or less. Specifically, the above V 336 It may be 1% or more, 2% or more, or 3% or more, and may be 75% or less, 80% or less, 85% or less, 90% or less, 95% or less, 100% or less, 105% or less, 110% or less, 115% or less, or 120% or less. The above V 336 When the viscosity is within the range described above, the increase in viscosity of the positive electrode slurry composition over time is suppressed, and even if the positive electrode slurry composition is not used immediately after production, it can exhibit a viscosity suitable for use in forming the positive electrode layer, and the manufactured positive electrode slurry composition can be stored for a predetermined period of time.

[0106] According to one embodiment of the present invention, the viscosity of the mixture, the cathode slurry composition precursor, and the cathode slurry composition may be independently 20,000 cP or less. Specifically, the viscosity of the mixture, the cathode slurry composition precursor, and the cathode slurry composition may be independently 0 cP or more, or 3,000 cP or more, and may be 9,000 cP or less, 10,000 cP or less, 11,000 cP or less, 12,000 cP or less, 13,000 cP or less, 14,000 cP or less, 15,000 cP or less, 16,000 cP or less, 17,000 cP or less, 18,000 cP or less, 19,000 cP or less, or 20,000 cP or less. When the viscosity is within the above range, the viscosity can be maintained at a low level during the production of the cathode slurry composition, and the cathode slurry composition can have a viscosity suitable for use in forming the cathode layer.

[0107] Method for manufacturing a positive electrode Furthermore, the present invention provides a method for manufacturing a positive electrode.

[0108] The method for manufacturing a positive electrode according to the present invention may include the step of manufacturing a positive electrode using a positive electrode slurry composition manufactured by the method for manufacturing a positive electrode slurry composition described above.

[0109] Specifically, the method for manufacturing a positive electrode of the present invention may include the steps of (A) manufacturing a positive electrode slurry composition by the method for manufacturing the positive electrode slurry composition, and (B) applying the positive electrode slurry composition onto a current collector and drying it to form a positive electrode layer.

[0110] Therefore, the method for manufacturing a positive electrode according to the present invention may include a method for manufacturing the positive electrode slurry composition, thereby enabling the process to be carried out as described in steps (S1) and (S2) above in the method for manufacturing the positive electrode slurry composition described above.

[0111] The steps of the present invention will be described in detail below.

[0112] (A) Step The method includes step (A) of producing a positive electrode slurry composition by the method for producing the positive electrode slurry composition described above.

[0113] The step of producing the positive electrode slurry composition includes the process of producing the positive electrode slurry composition by the method for producing the positive electrode slurry composition described above, specifically, (S1) putting the positive electrode active material, conductive material, binder and non-aqueous solvent into a mixer and mixing them to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C, (S2) cooling the mixture to a temperature of -30°C to 15°C to produce a positive electrode slurry composition precursor, and (S3) maintaining the temperature of the positive electrode slurry composition precursor, V 72 The step of producing a positive electrode slurry composition in which is 0% or more and 50% or less, and the V n This is the viscosity increase rate when the temperature of the positive electrode slurry composition precursor is maintained for n hours, and this viscosity increase rate may be expressed by mathematical formula 1 described herein.

[0114] (B) Step The following step may be included: (B) applying the positive electrode slurry composition onto the current collector and drying it to form a positive electrode layer.

[0115] In step (B) above, the manufactured positive electrode slurry composition is applied to and dried on the current collector to form a positive electrode layer.

[0116] Step (B) can be carried out by a conventional method for manufacturing a positive electrode, except that the positive electrode slurry composition of step (A) is used.

[0117] For example, a positive electrode slurry composition produced by a method for producing a positive electrode slurry composition according to one embodiment of the present invention can be applied to one surface of a positive electrode current collector or onto the positive electrode, and then dried and rolled to form a positive electrode layer on the positive electrode current collector. The positive electrode layer can be formed such that the porosity is 10% to 30% by volume, specifically 15% to 30% by volume, and more specifically 18% to 27% by volume.

[0118] A method for manufacturing a positive electrode according to one embodiment of the present invention further includes, immediately before step (B), a step (A1) of transferring the positive electrode slurry composition to a means for coating the positive electrode active material composition for coating the positive electrode slurry composition in step (B), wherein the transfer may be carried out at a temperature of -30°C to 15°C. When the transfer is carried out within the temperature range, the increase in viscosity of the positive electrode slurry composition can be suppressed to the maximum extent, and a more uniform positive electrode layer can be formed.

[0119] The positive electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., can be used. The positive electrode current collector can usually have a thickness of 3 to 500 μm, and fine irregularities can be formed on the surface of the current collector to enhance the adhesion of the positive electrode active material. For example, it may be used in various forms such as film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0120] Alternatively, the positive electrode slurry composition may be manufactured, for example, by casting it onto another support, peeling it off the support, and then laminating the resulting film onto the positive electrode current collector.

[0121] Furthermore, an electrochemical element including the positive electrode can be manufactured using the positive electrode manufactured by the positive electrode manufacturing method described above. Specifically, the electrochemical element may be a battery, a capacitor, or more specifically, a lithium secondary battery.

[0122] The method for manufacturing a positive electrode according to the present invention may also be a method for manufacturing a positive electrode for a lithium secondary battery, and the positive electrode manufactured by the above manufacturing method may be used as a positive electrode for a lithium secondary battery.

[0123] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode, wherein the positive electrode may be a positive electrode manufactured by the positive electrode manufacturing method described above.

[0124] Furthermore, the lithium secondary battery may selectively further include a battery container for housing the electrode assembly comprising the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0125] In the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0126] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy can be used. The negative electrode current collector can usually have a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the negative electrode active material. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0127] The negative electrode active material layer selectively includes a binder and a conductive material together with the negative electrode active material.

[0128] As the negative electrode active material, compounds capable of reversible intercalation and deintercalation of lithium can be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. βExamples include metal oxides that can be doped and dedoped with lithium, such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more mixtures of these can be used. A metallic lithium thin film may also be used as the negative electrode active material. In addition, both low-crystallinity carbon and high-crystallinity carbon can be used as the carbon material. Examples of low-crystalline carbon include soft carbon and hard carbon, while examples of high-crystalline carbon include amorphous, plate-like, flaky, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0129] The negative electrode active material can be included in an amount of 80 to 99 parts by weight per 100 parts by weight of the total weight of the negative electrode active material layer.

[0130] The aforementioned binder is a component that helps to bond the conductive material, active material, and current collector, and is usually added in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0131] The conductive material is a component for further improving the conductivity of the negative electrode active material, and can be added in amounts of 10 parts by weight or less, preferably 5 parts by weight or less, per 100 parts by weight of the total weight of the negative electrode active material layer. Such a conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and can be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0132] For example, the negative electrode active material layer can be manufactured by coating a negative electrode composite material, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and then drying it, or by casting the negative electrode composite material onto another support, peeling it off this support, and then laminating the resulting film onto the negative electrode current collector.

[0133] On the other hand, in the secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without particular limitations, but those with low resistance to ion movement of the electrolyte and excellent electrolyte impregnation ability are particularly preferred. Specifically, porous polymer films, such as porous polymer films made from polyolefin polymers like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or laminated structures of two or more layers thereof, can be used. Alternatively, ordinary porous nonwoven fabrics, such as nonwoven fabrics made from high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, coated separators containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and may be used selectively in single-layer or multi-layer structures.

[0134] Furthermore, the electrolytes used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0135] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0136] The organic solvent can be used without particular limitations, as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Suitable solvents include carbonate-based solvents such as carbonate (PC); alcohol-based solvents such as ethanol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group with 2 to 20 carbon atoms, and may include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among these, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant, which can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred. In this case, the cyclic carbonate and linear carbonate can be mixed in a volume ratio of about 1:1 to about 1:9 to produce an electrolyte with excellent performance.

[0137] The lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions for use in lithium secondary batteries. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt falls within this range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0138] In addition to the components of the electrolyte, the electrolyte may further contain one or more additives for purposes such as improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity, such as haloalkylene carbonate compounds like difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride. Here, the additive may be present in amounts of 0.1 to 5 parts by weight per 100 parts by weight of the total weight of the electrolyte.

[0139] As described above, lithium secondary batteries containing the positive electrode material according to the present invention exhibit excellent discharge capacity, output characteristics, and lifespan characteristics in a stable manner, making them useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0140] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0141] The aforementioned battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0142] The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch-type, or coin-type using a can.

[0143] In addition to being usable as a battery cell for powering small devices, the lithium secondary battery according to the present invention can also be preferably used as a unit battery in medium- and large-sized battery modules containing a large number of battery cells.

[0144] The present invention will be described in detail below with reference to examples. However, the examples of the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to give a more complete explanation of the present invention to a person of average skill in the art.

[0145] Manufacturing example Manufacturing Example 1 NiSO4, CoSO4, and MnSO4 were dissolved in water in amounts such that the molar ratio of nickel:cobalt:manganese was 96:2:2, and a 2M transition metal-containing solution was prepared.

[0146] The container holding the transition metal-containing solution was further connected to a 200 L batch reactor set to 55°C, along with a 25 wt% NaOH solution and a 15 wt% NH4OH aqueous solution.

[0147] Next, deionized water was added to the batch reactor, and then nitrogen gas was purged to remove dissolved oxygen from the water, creating a non-oxidizing atmosphere inside the reactor. Then, NaOH was added, and the mixture was stirred at a stirring speed of 250 rpm to maintain the pH inside the coprecipitation reactor at 11.7.

[0148] Subsequently, the transition metal-containing solution was added to the coprecipitation reactor at a rate of 250 mL / hr, an aqueous NH4OH solution was added at a rate of 40 mL / hr, and an aqueous NaOH solution was added at a rate that maintained the pH of the reaction solution at 11.7. After 6 hours of reaction, stirring was stopped, and the upper layer was removed to concentrate the solution. This process was repeated 4 to 5 times to obtain the average particle size (D 50 The particles were grown until they reached a size of approximately 14 μm.

[0149] The transition metal oxide precursor particles produced in this way are filtered using a filter press, then dried at 130°C for 24 hours, and Ni 0.96 Co 0.02 Mn 0.02 A positive electrode active material precursor having a composition represented by (OH)2 was obtained. Next, the positive electrode active material precursor and LiOH·H2O were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.06, and the mixture was calcined at 775°C for 13.5 hours under an oxygen atmosphere to form LiNi 0.96 Co 0.02 Mn 0.02 It has a composition represented by O2, and an average particle size (D 50 The particle size was 14 μm, and a secondary particle form of the cathode active material (lithium transition metal oxide) was produced.

[0150] Manufacturing Example 2 Cathode active material precursor [Composition: Ni 0.96 Co 0.02 Mn 0.02 (OH)2, average particle size (D 50Mix 4.5 μm of [ ] and LiOH so that the molar ratio of (Ni+Co+Mn):Li is 1:1.05, and then, under an oxygen atmosphere, perform primary calcination at 850°C for 9 hours to produce a calcined product. After crushing the aforementioned calcined product, it is subjected to secondary calcination at 750°C for 9 hours under an oxygen atmosphere to produce LiNi 0.96 Co 0.02 Mn 0.02 It has a composition represented by O2, and an average particle size (D 50 The particle size was 14 μm, and a single-particle form of cathode active material (lithium transition metal oxide) was produced.

[0151] Example 1 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (Kureha KF9709, manufactured by Kureha), and non-aqueous solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 1 were left in a 20°C chamber for 6 hours to allow each of their temperatures to reach 20°C.

[0152] At room temperature, 200 g of the positive electrode active material, 3.43 g of carbon black as a conductive material, and 4.36 g of PVdF as a binder were dispersed and mixed in 80.8 g of non-aqueous solvent (NMP) using a homodisper mixer (Homo Disper 2.5, manufactured by PRIMIX) to produce a mixture with a solid content of 72.0% by weight. During mixing, the temperature of the mixture rose due to the resistance between the mixer and the mixture, and the mixing temperature was maintained at 45°C.

[0153] The mixture was cooled to 0°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0154] Example 2 The cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was cooled to 10°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor.

[0155] Example 3 The cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor.

[0156] Example 4 The cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was cooled to -10°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor.

[0157] Example 5 The cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was cooled to -20°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor.

[0158] Example 6 The cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was cooled to -30°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor.

[0159] Example 7 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (Kureha KF9709, manufactured by Kureha), and solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 1 were left in a 10°C chamber for 6 hours to allow their respective temperatures to reach 10°C.

[0160] Using a homodisper mixer (PRIMIX, Homo Disper 2.5), 200 g of the positive electrode active material, 3.43 g of carbon black as a conductive material, and 4.36 g of PVdF as a binder were dispersed and mixed in 80.8 g of non-aqueous solvent (NMP) to produce a mixture with a solid content of 72.0% by weight. The heat generated by the resistance between the mixer and the mixture during mixing was removed, and the mixing temperature was maintained at 10°C.

[0161] The mixture was cooled to -10°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor to produce the cathode slurry composition.

[0162] Example 8 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (Kureha KF9709, manufactured by Kureha), and solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 1 were left in a chamber at -10°C for 6 hours to allow their respective temperatures to reach -10°C.

[0163] A mixture with a solid content of 72.0% by weight was prepared by dispersing and mixing 200g of the positive electrode active material, 3.43g of carbon black as a conductive material, and 4.36g of PVdF as a binder in 80.8g of non-aqueous solvent (NMP) using a homodisper mixer (Homo Disper 2.5, manufactured by PRIMIX) while controlling the internal surface and internal space of the mixing chamber to be -10°C. Heat generated by the resistance between the mixer and the mixture during mixing was removed, and the mixing temperature was maintained at -10°C.

[0164] The mixture was cooled to -10°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor to produce the cathode slurry composition.

[0165] Example 9 The cathode slurry composition was produced in the same manner as in Example 1, except that the cathode active material produced in Production Example 2 was mixed to produce a mixture, the mixture was cooled to -10°C to produce a cathode slurry composition precursor, and the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0166] Example 10 A cathode slurry composition was produced in the same manner as in Example 1, except that LiNiO2 was mixed as the cathode active material to produce a mixture, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0167] Example 11 LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 The cathode slurry composition was produced in the same manner as in Example 1, except that O2 was mixed to produce a mixture, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0168] Example 12 A cathode slurry composition was produced in the same manner as in Example 1, except that a mixture was prepared by mixing a particulate secondary structure containing LiFePO4 having an olivine crystal structure as the cathode active material, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0169] Example 13 Li as the positive electrode active material 1.2 Ni 0.35 Mn 0.65The cathode slurry composition was produced in the same manner as in Example 1, except that O2 was mixed to produce a mixture, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0170] Example 14 A cathode slurry composition was produced in the same manner as in Example 1, except that a cathode material was prepared by mixing the cathode active material produced in Production Example 1 with a particulate secondary structure containing LiFePO4 having an olivine crystal structure in a weight ratio of 50:50 to produce a cathode active material, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0171] Example 15 The positive electrode active material is the positive electrode active material produced in Production Example 1 and Li 1.2 Ni 0.35 Mn 0.65 The cathode slurry composition was produced in the same manner as in Example 1, except that a mixture was prepared by mixing a cathode material containing O2 in a 50:50 weight ratio, the mixture was cooled to -5°C to produce a cathode slurry composition precursor, and the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0172] Example 16 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (Kureha KF9709, manufactured by Kureha), and non-aqueous solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 1 were left in a 20°C chamber for 6 hours to allow each of their temperatures to reach 20°C.

[0173] At room temperature, 200 g of the positive electrode active material, 3.43 g of carbon black as a conductive material, and 4.36 g of PVdF as a binder were dispersed and mixed in 80.8 g of non-aqueous solvent (NMP) using a homodisper mixer (Homo Disper 2.5, manufactured by PRIMIX) to produce a mixture with a solid content of 72% by weight. During mixing, the temperature of the mixture rose due to the resistance between the mixer and the mixture, and the mixing temperature was maintained at 45°C.

[0174] The mixture was cooled to -23°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor to produce the cathode slurry composition.

[0175] Comparative Example 1 The cathode slurry composition was produced in the same manner as in Example 1, except that the mixture was cooled to 20°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0176] Comparative Example 2 The cathode slurry composition was produced in the same manner as in Example 1, except that the mixture was cooled to 40°C to produce a cathode slurry composition precursor, and then the cathode slurry composition was produced by storing the cathode slurry composition precursor while maintaining its temperature.

[0177] Comparative Example 3 A cathode slurry composition was prepared in the same manner as in Example 1, except that the mixture was transferred to a constant temperature and humidity chamber without a cooling step and stored while being maintained at 50°C to produce the cathode slurry composition.

[0178] Comparative Example 4 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (Kureha KF9709, manufactured by Kureha), and solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 2 were left in a chamber at -10°C for 6 hours to allow their respective temperatures to reach -10°C.

[0179] A mixture with a solid content of 72.0% by weight was prepared by dispersing and mixing 200g of the positive electrode active material, 3.43g of carbon black as a conductive material, and 4.36g of PVdF as a binder in 80.8g of non-aqueous solvent (NMP) using a homodisper mixer (Homo Disper 2.5, manufactured by PRIMIX) while controlling the internal surface and internal space of the mixing chamber to be -10°C. Heat generated by the resistance between the mixer and the mixture during mixing was removed, and the mixing temperature was maintained at -10°C.

[0180] The cathode slurry composition was prepared in the same manner as in Example 8, except that the mixture was transferred in a constant temperature and humidity chamber without a cooling step and stored while being maintained at 50°C to produce the cathode slurry composition.

[0181] Comparative Example 5 The cathode active material, carbon black (Denka Black, manufactured by Denka), PVdF (KF9709, manufactured by Kureha), and non-aqueous solvent (N-methylpyrrolidone (NMP), manufactured by Oi Chemical Co., Ltd.) produced in the above manufacturing example 1 were left in a 30°C chamber for 6 hours to allow each of their temperatures to reach 30°C.

[0182] At room temperature, 200 g of the positive electrode active material, 3.43 g of carbon black as a conductive material, and 4.36 g of PVdF as a binder were dispersed and mixed in 80.8 g of solvent (NMP) using a homodisper mixer (Homo Disper 2.5, manufactured by PRIMIX) to produce a mixture with a solid content of 72.0% by weight. During mixing, the temperature of the mixture rose due to the resistance between the mixer and the mixture, and the mixing temperature was maintained at 55°C.

[0183] The mixture was cooled to -10°C to produce a cathode slurry composition precursor, and then stored while maintaining the temperature of the cathode slurry composition precursor to produce the cathode slurry composition.

[0184] Experimental example Viscosity evaluation Using a viscometer (TOKI Corporation, viscometer TV-22), the viscosity (cP) of each mixture and cathode slurry composition produced in the above examples and comparative examples was measured, and the viscosity increase rate (V) was determined. n The percentages (%) were calculated and are shown in Table 1 below.

[0185] Specifically, the viscosity of each mixture and cathode slurry composition produced in the above examples and comparative examples was measured using a viscometer at 25°C and 1 rpm, and the viscosity of the mixture (VS1[cP]), the viscosity of the cathode slurry composition (VS2[cP]), and the percentage of the difference between the viscosity of the cathode slurry composition and the mixture ((VS2[cP]-VS1[cP])) relative to the viscosity of the mixture (VS1[cP]) were calculated (V n The percentages (%) were calculated and are shown in Table 1 below. The viscosity of the positive electrode slurry composition was measured when the temperature of the positive electrode slurry composition precursor was maintained for 24 hours, 72 hours, 168 hours, and 336 hours, respectively.

[0186] For reference, when measuring viscosity at 25°C, only viscosity changes within the error range occur. Furthermore, if the viscosity exceeds 15,000 cP, electrode manufacturing becomes impossible.

[0187] [Table 1A] [Table 1B]

[0188] Referring to Table 1, in the case of a positive electrode slurry composition produced in Examples 1 to 16, that is, a positive electrode slurry composition produced by the steps of (S1) mixing a positive electrode active material, a conductive material, and a binder in a non-aqueous solvent to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C to 45°C, (S2) cooling the mixture to -30°C to 15°C to produce a positive electrode slurry composition precursor, and (S3) maintaining the temperature of the positive electrode slurry composition precursor, V 72 Confirm that it is between 0% and 50%, V 24 It is between -5% and 30%, V 168 It is between 0% and 80%, V 336 The concentration is between 1% and 120%, and the viscosity of the mixture and V 24 , V 72 , V 168 , V 336 It was confirmed that the level was below 20,000 cP.

[0189] In particular, in the case of the positive electrode slurry compositions produced in Examples 6 and 16, that is, the positive electrode slurry compositions produced by the step of cooling the mixture to a temperature of -30°C or higher and -23°C or lower to produce a positive electrode slurry composition precursor, the viscosity was 3,800 cP or less when the temperature of the positive electrode slurry composition precursor was maintained for 24 hours, 3,950 cP or less when it was maintained for 72 hours, 4,100 cP or less when it was maintained for 168 hours, and 4,050 cP or less when it was maintained for 336 hours. 24 is 3.1% or less, V 72 is 7.7% or less, V 168 is 12.3% or less, V 336 It was confirmed that the viscosity was 16.9% or less. This means that, even after time has elapsed, the viscosity of the cathode slurry composition remains low and the viscosity increase rate is low, even when the step of cooling the mixture to a temperature of -30°C or higher and -23°C or lower is included in the process of producing the cathode slurry composition precursor.

[0190] On the other hand, if the positive electrode slurry compositions produced in Comparative Examples 1 to 4 include a step of producing a positive electrode slurry composition precursor that does not include a step of cooling the mixture or does not include a step of cooling the mixture to 15°C or below, then V 72 Confirm that it is over 50%, V 24 It is over 30%, V 168 It is over 80%, V 336 The viscosity was over 120%, and after a predetermined time had elapsed, it reached the intrinsic viscosity of 30,000 cP, the limit of the viscometer. It was confirmed that further measurement was difficult and electrode manufacturing was impossible.

[0191] Furthermore, in the step of producing a positive electrode slurry composition in Comparative Example 5, that is, by adding the positive electrode active material, conductive material, binder, and non-aqueous solvent to a mixer and mixing them to produce a mixture with a solid content of more than 60% by weight, it was confirmed that when the temperature of the mixture was above 45°C, the viscosity of the produced mixture was 8,000 cP or higher, which was considerably higher than that of the example.

[0192] In other words, by performing all steps (S1) to (S3), it is possible to produce a mixture and cathode slurry composition with low viscosity and a cathode slurry composition with a low viscosity increase rate.

Claims

1. (S1) A step of putting a positive electrode active material, a conductive material, a binder and a non-aqueous solvent into a mixer and mixing them to produce a mixture having a solid content of more than 60% by weight and a temperature of -20°C or higher and 45°C or lower, (S2) A step of cooling the mixture to a temperature of -30°C or higher and 15°C or lower to produce a cathode slurry composition precursor, (S3) Maintain the temperature of the positive electrode slurry composition precursor, V ７２ The step of producing a positive electrode slurry composition in which the content is 0% or more and 50% or less, The aforementioned V ｎ This is the viscosity increase rate when the temperature of the positive electrode slurry composition precursor is maintained for n hours. The viscosity increase rate is represented by the following mathematical formula 1, a method for producing a positive electrode slurry composition. [Mathematical formula 1] Viscosity increase rate (V ｎ [%]) = (VS2 [cP] - VS1 [cP] x 100 / VS1 [cP]) In the above mathematical formula 1, VS1 is the viscosity [cP] of the mixture, and VS2 is the viscosity [cP] of the positive electrode slurry composition.

2. The method for producing a positive electrode slurry composition according to claim 1, wherein the mixer has a surface temperature of -30°C or higher and 20°C or lower.

3. The mixer includes a mixing chamber, The method for producing a positive electrode slurry composition according to claim 1, wherein the mixing is performed such that the temperature of the internal surface and the internal space of the mixing chamber are independently -30°C or higher and 20°C or lower.

4. The method for producing a positive electrode slurry composition according to claim 1, wherein the positive electrode active material comprises one or more lithium complex transition metal compounds having compositions represented by the following chemical formulas 1 to 4. [Chemical formula 1] Li ａ [Ni ｂ Co ｃ Mn ｄ M １ １－（ｂ＋ｃ＋ｄ） ]O ２ In the aforementioned chemical formula 1, M １ This is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ a ≤ 1.1, 0 < b < 1, 0 < c < 1, 0 < d < 1, 0 < b + c + d ≤ 1, [Chemical formula 2] Li ｅ Ni １－ｆ M ２ ｆ O ２ In the aforementioned chemical formula 2, M ２ is one or more selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ e ≤ 1.1 and 0 ≤ f < 1, [Chemical formula 3] Li ｇ Ni ｈ Mn ｉ M ３ ｊ O ２ In the aforementioned chemical formula 3, M ３ is one or more selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, B, and Bi. 1.0 ≤ g ≤ 1.5, 0 ≤ h ≤ 0.5, 0.4 ≤ i ≤ 0.9, 0 ≤ j ≤ 0.1, [Chemical formula 4] LiFe １－ｋ M ４ ｋ PO ４ In the aforementioned chemical formula 4, M ４ is one or more selected from the group consisting of Mn, Co, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Te, Ir, Gd, Sm, Sb, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0 ≤ k < 1.

5. The method for producing a positive electrode slurry composition according to claim 1, wherein the positive electrode active material comprises two or more lithium complex transition metal compounds having compositions represented by the following chemical formulas 1 to 4. [Chemical formula 1] Li ａ [Ni ｂ Co ｃ Mn ｄ M １ １－（ｂ＋ｃ＋ｄ） ]O ２ In the aforementioned chemical formula 1, M １ This is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ a ≤ 1.1, 0 < b < 1, 0 < c < 1, 0 < d < 1, 0 < b + c + d ≤ 1, [Chemical formula 2] Li ｅ Ni １－ｆ M ２ ｆ O ２ In the aforementioned chemical formula 2, M ２ is one or more selected from the group consisting of Mn, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ e ≤ 1.1 and 0 ≤ f < 1, [Chemical formula 3] Li ｇ Ni ｈ Mn ｉ M ３ ｊ O ２ In the aforementioned chemical formula 3, M ３ is one or more selected from the group consisting of Co, Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, B, and Bi. 1.0 ≤ g ≤ 1.5, 0 ≤ h ≤ 0.5, 0.4 ≤ i ≤ 0.9, 0 ≤ j ≤ 0.1, [Chemical formula 4] LiFe １－ｋ M ４ ｋ PO ４ In the aforementioned chemical formula 4, M ４ is one or more selected from the group consisting of Mn, Co, Na, K, Mg, Al, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Te, Ir, Gd, Sm, Sb, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0 ≤ k < 1.

6. A method for producing a positive electrode slurry composition according to claim 1, wherein the positive electrode active material comprises a lithium composite transition metal compound having a composition represented by the following chemical formula 5. [Chemical formula 5] Li ａ’ [Ni ｂ’ Co ｃ’ Mn ｄ’ M ５ １－（ｂ’＋ｃ’＋ｄ’） ]O ２ M ５ This is one or more elements selected from the group consisting of Na, K, Mg, Al, Fe, Cr, Y, Sn, Ti, B, P, Zr, Ru, Nb, W, Ba, Sr, La, Ga, Gd, Sm, Ca, Ce, F, Ta, Mo, Sc, V, Zn, Cu, In, S, and Bi. 0.9 ≤ a' ≤ 1.1, 0.6 ≤ b' < 1, 0 < c' < 0.4, 0 < d' < 0.4, 0 < b' + c' + d' ≤ 1.

7. The method for producing a positive electrode slurry composition according to claim 1, wherein the mixing is carried out such that, based on 100 parts by weight of solids, the positive electrode active material is 85 parts by weight or more and 99 parts by weight or less, the conductive material is 0.5 parts by weight or more and 10 parts by weight or less, and the binder is 0.5 parts by weight or more and 10 parts by weight or less.

8. A method for producing a positive electrode slurry composition according to claim 1, wherein the solid content is 70% by weight or more and 85% by weight or less.

9. The method for producing a cathode slurry composition according to claim 1, wherein (S2) is to cool the mixture to a temperature of -30°C or higher and -23°C or lower to produce a cathode slurry composition precursor.

10. V ２４ A method for producing a positive electrode slurry composition according to claim 1, wherein the concentration is -5% or more and 30% or less.

11. V １６８ A method for producing a positive electrode slurry composition according to claim 1, wherein the amount is 0% or more and 80% or less.

12. V ３３６ A method for producing a positive electrode slurry composition according to claim 1, wherein the amount is 1% or more and 120% or less.

13. The method for producing a positive electrode slurry composition according to claim 1, wherein the mixture, the positive electrode slurry composition precursor, and the positive electrode slurry composition each independently have a viscosity of 20,000 cP or less.

14. (A) A step of manufacturing a positive electrode slurry composition by a manufacturing method described in any one of claims 1 to 13, (B) A method for producing a positive electrode, comprising the steps of (B) applying the positive electrode slurry composition onto a current collector and drying it to form a positive electrode active material layer.

15. Immediately before step (B), the step (A1) further includes transferring the positive electrode slurry composition to a means for coating the positive electrode active material composition, The method for manufacturing a positive electrode according to claim 14, wherein the transfer is carried out at a temperature of -30°C or higher and 15°C or lower.

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