Molded body

Abstract

The present invention relates to a molded body having appropriate strength and including a positive electrode active material precursor having excellent thermal conductivity, and relates to a molded body including a positive electrode active material precursor and a lithium-containing raw material, wherein a load at fracture and thermal conductivity satisfy specific ranges, respectively.

Description

molded body

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0001055 filed on January 3, 2025, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a molded body comprising a positive electrode active material precursor, and specifically to a molded body having appropriate strength and excellent thermal conductivity.

[0005]

[0006] With the recent increase in technological development and demand for mobile devices and electric vehicles, the demand for rechargeable batteries as an energy source is rapidly rising. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0007] Lithium transition metal oxides, such as lithium cobalt oxide like LiCoO2, lithium nickel oxide like LiNiO2, lithium manganese oxide like LiMnO2 or LiMn2O4, and lithium iron phosphate oxide like LiFePO4, have been developed as cathode active materials for lithium secondary batteries, and recently, Li[Ni a Co b Mn c ]O2, Li[Ni a Co b Al c ]O2, Li[Ni a Co b Mn c Al d Lithium composite transition metal oxides containing two or more transition metals, such as O2, have been developed and are widely used.

[0008] Meanwhile, the cathode active material is generally manufactured by mixing a cathode active material precursor powder, such as a complex transition metal hydroxide, a complex transition metal oxide, the transition metal itself, a transition metal oxide, a transition metal hydrate, a transition metal hydroxide, a transition metal carbonate, or a transition metal chloride, with a lithium raw material, placing the mixture into a crucible, and then calcining it. However, in this case, the degree of heat transfer to the mixture at the bottom and the mixture at the top of the crucible may differ, so the physical properties of the cathode active material manufactured in the same crucible may not be uniform. Consequently, there is a problem in that the mixture cannot be filled to the brim and calcined.

[0009] Therefore, there is a need to develop a method that enables the production of a positive electrode active material with uniform physical properties by ensuring good heat transfer even when the mixture fills the crucible.

[0010]

[0011] The present invention aims to solve the above-mentioned problems by providing a molded body comprising a positive electrode active material precursor having appropriate strength and excellent thermal conductivity.

[0012]

[0013] To solve the above problem, the present invention provides a molded body.

[0014]

[0015] (1) The present invention provides a molded body comprising a positive electrode active material precursor; and a lithium-containing raw material; wherein, when a load cell of 10 kN is compressed as a free load using a universal testing machine, the load measured when the sample is destroyed by the compressive load is greater than 4 N and less than or equal to 1050 N, and the thermal conductivity is greater than or equal to 0.25 W / (m·K) and less than or equal to 2.0 W / (m·K).

[0016] (2) The present invention provides a molded body in which, in (1) above, when a load cell of 10 kN is compressed as a free load using the universal testing machine, the load measured when the sample is destroyed by the compressive load is 5 N to 1050 N.

[0017] (3) The present invention provides a molded body in which the thermal conductivity of (1) or (2) is 0.30 W / (m·K) or higher and 2.0 W / (m·K) or lower.

[0018] (4) The present invention provides a molded body in which, in any one of (1) to (3) above, the positive active material precursor comprises one or more selected from a complex transition metal hydroxide, a complex transition metal oxide, a transition metal, a transition metal oxide, a transition metal hydrate, a transition metal hydroxide, a transition metal carbonate, and a transition metal chloride.

[0019] (5) The present invention provides a molded body in which, in any one of (1) to (4), the ratio (M:Li) of the total number of moles of transition metal (M) included in the positive active material precursor and the number of moles of lithium (Li) included in the lithium-containing raw material is 1:1 to 1.05.

[0020] (6) The present invention provides a molded body in which, in any one of (1) to (5), the molded body does not contain a binder.

[0021] (7) The present invention provides a molded body having an average porosity of 0.30 or more and 0.60 or less in any one of (1) to (6).

[0022] (8) The present invention provides a molded body having an average porosity of 0.45 or more and 0.60 or less in any one of (1) to (7).

[0023] (9) The present invention provides a molded body in any one of (1) to (8), wherein the molded body is in the shape of a charcoal, a cylinder, a granule, a plate, a truncated triangular cone, an elongated ellipse, a rectangular prism, or a truncated cone.

[0024]

[0025] When a positive electrode active material is manufactured using a molded body according to the present invention, a positive electrode active material with uniform physical properties can be easily mass-produced.

[0026] That is, when manufacturing a positive electrode active material using a molded body according to the present invention, a positive electrode active material with uniform physical properties can be provided, and productivity can be increased.

[0027]

[0028] Figure 1 is a graph showing the relationship between the briquette mass (m) and the load (F) at failure.

[0029]

[0030] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0031] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0032]

[0033] In this specification, terms such as 'comprising,' 'having,' or 'having' are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0034] In this specification, the term "on" means not only cases where one configuration is formed on the immediate upper surface of another configuration, but also cases where a third configuration is interposed between these configurations.

[0035]

[0036] molded body

[0037] The present invention provides a molded body comprising a positive electrode active material precursor and a lithium-containing raw material. The molded body according to the present invention has a load (hereinafter, load at breakage) measured when the sample is destroyed by the compressive load when a load cell of 10 kN is compressed as a free load using a universal testing machine, which is greater than 4 N and less than or equal to 1050 N, and a thermal conductivity of 0.25 W / (m·K) or more and 2.0 W / (m·K) or less.

[0038]

[0039] The inventors have discovered that, regardless of the shape of the molded body, when the load at the time of fracture of the molded body is greater than 4 N and less than or equal to 1050 N, the molded body is not damaged during the process of moving the molded body, and when the thermal conductivity of the molded body is 0.25 W / (m·K) or more and 2.0 W / (m·K) or less, a positive electrode active material having uniform physical properties can be mass-produced, and thus completed the present invention.

[0040] Meanwhile, if the load at fracture of the molded body is 4N or less, there is a problem that the molded body is prone to breaking; if it exceeds 1050N, the molded body may not sinter well due to its high strength, and it may not pulverize well during the grinding process for post-processing. Additionally, if the thermal conductivity of the molded body is less than 0.25W / (m·K), there is a problem that a cathode active material with uniform physical properties cannot be manufactured; and if it exceeds 2.0W / (m·K), heat transfer is too efficient, leading to over-sintering and the formation of large particles, or the pores are too small, which may make gas exchange during the sintering reaction unfavorable. In other words, while there are advantages such as the molded body not breaking easily and having higher thermal conductivity as the strength of the molded body increases, if the strength is too high, there are disadvantages in the sintering and grinding processes, which may result in a large amount of wasted raw material, reduced production volume, and degraded quality, making it difficult to produce high-quality cathode materials.

[0041]

[0042] According to the present invention, when the molded body is compressed with a 10kN load cell as a free load using a universal testing machine, the load measured when the sample is destroyed by the compressive load may preferably be 5N to 1050N. Specifically, the load at the time of destruction of the molded body may be 5N or more, or 6N or more, and may be 1047N or less, 1048N or less, 1049N or less, or 1050N or less.

[0043] According to the present invention, the thermal conductivity of the molded body may preferably be 0.30 W / (m·K) or higher and 2.0 W / (m·K) or lower. Specifically, the thermal conductivity of the molded body may be 0.30 W / (m·K) or higher, or 0.35 W / (m·K) or higher, and may be 0.45 W / (m·K) or lower, 0.50 W / (m·K) or lower, 0.60 W / (m·K) or lower, 0.70 W / (m·K) or lower, 0.80 W / (m·K) or lower, 0.90 W / (m·K) or lower, 1.0 W / (m·K) or lower, 1.5 W / (m·K) or lower, or 2.0 W / (m·K) or lower.

[0044]

[0045] For reference, the inventors conducted experiments and confirmed that there is a linear relationship between the load (F, unit: N) at the time of fracture of the molded body (briquette) and the mass (m, unit: g) of the molded body (briquette) as shown in Equation 1 below. Figure 1 is a graph showing the relationship between the briquette mass (m) and the load (F) at the time of fracture, and Equation 1 as follows was derived through actual measurement data.

[0046] [Equation 1]

[0047] F = 123.9 × m - 733.31

[0048] In Equation 1, F represents the load at the time of fracture of the molded body (N), and m represents the mass of the briquette (g).

[0049] Equation 1 above was determined based on 21 experimental data points, and the coefficient of determination (R 2 ) has a reliability of 0.77.

[0050] The above Equation 1 is derived from the briquette (roller compression) method, and when generalized, it can be expressed as Equation 2 below.

[0051] [Equation 2]

[0052] F = 123.9 × C × (k 성형체 ) n' - 733.31

[0053] In Equation 2, k 성형체ε is the thermal conductivity of the molded body, n'=1 / n, C is a constant, k 성형체 ∝ m n n is a coefficient that varies depending on the molding equipment and conditions.

[0054] In addition, the load (F) and thermal conductivity (k) at the time of fracture of the molded body 성형체 The relationship shown in Equation 3 below holds between ) (Governing equation between load and thermal conductivity at failure).

[0055] [Equation 3]

[0056] F = C × k n 성형체 + b

[0057] In Equation 3, C and b are constants, and n is a coefficient that varies depending on the molding equipment and conditions.

[0058] And, k 성형체 ε is the thermal conductivity of the molded body, and is the thermal conductivity (k) of the solid portion (anode material) within the molded body (a composite structure composed of a solid (e.g., anode material) and pores). s Thermal conductivity of ) and air (pores) (k air It is defined as shown in Equation 4 below by ) and average porosity (φ).

[0059] [Equation 4]

[0060] k 성형체 = k s ×(1-φ) + k air ×φ

[0061] Meanwhile, in the case of the vertical compression method (Press method), the load at the time of failure of the molded body can be simplified as shown in Equation 5 below.

[0062] [Equation 5]

[0063] F = C × k 성형체 n

[0064] According to the present invention, the load at the time of fracture of the molded body must be 1050 N or less, and to achieve this, the strength of the molded body is optimized by appropriately adjusting the pressure and porosity, and as a result, it is possible to manufacture a positive electrode active material of excellent quality.

[0065]

[0066] According to the present invention, the positive electrode active material precursor may comprise one or more selected from complex transition metal hydroxide, complex transition metal oxide, transition metal, transition metal oxide, transition metal hydrate, transition metal hydroxide, transition metal carbonate, and transition metal chloride.

[0067] The above composite transition metal hydroxide may include nickel and one or more transition metals selected from the group consisting of cobalt, manganese, and aluminum.

[0068] The above complex transition metal hydroxide may be represented by the following chemical formula 1.

[0069] [Chemical Formula 1]

[0070] Ni a1 Co b1 M 1 c1 M 2 d1 (OH) 2+x1

[0071] In the above chemical formula 1,

[0072] M 1 is Mn, Al, or a combination thereof, and

[0073] M 2 is an element that can be doped in addition to Ni, Co, Mn, and Al, and

[0074] 0 <a1<1.0, 0≤b1<1.0, 0≤c1<1.0, 0≤d1≤0.1, 0≤x1≤0.03이다.

[0075] The above composite transition metal oxide may include nickel and one or more transition metals selected from the group consisting of cobalt, manganese, and aluminum.

[0076] The above complex transition metal oxide may be represented by the following chemical formula 2.

[0077] [Chemical Formula 2]

[0078] Ni a2 Co b2 M 1 c M 2 d O 1+x2

[0079] In the above chemical formula 1,

[0080] M 1 is Mn, Al, or a combination thereof, and

[0081] M 2 is an element that can be doped in addition to Ni, Co, Mn, and Al, and

[0082] 0 <a2<1.0, 0≤b2<1.0, 0≤c2<1.0, 0≤d2≤0.1, 0≤x2≤0.03이다.

[0083] The above transition metal may be one or more selected from the group consisting of nickel, cobalt, manganese, and aluminum.

[0084] The above transition metal oxide may be one or more selected from the group consisting of nickel oxide, cobalt oxide, manganese oxide and aluminum oxide.

[0085] The above transition metal hydrate is a compound containing a transition metal and a water molecule, and may be one or more selected from the group consisting of nickel-containing hydrate, cobalt-containing hydrate, manganese-containing hydrate, and aluminum-containing hydrate.

[0086] The above transition metal hydroxide is a structure in which a transition metal is coordinated by a hydroxyl group, and may be one or more selected from the group consisting of nickel hydroxide, cobalt hydroxide, manganese hydroxide, and aluminum hydroxide.

[0087] The above transition metal carbonate is a compound composed of a transition metal and a carbonate, and may be one or more selected from the group consisting of nickel carbonate, cobalt carbonate, manganese carbonate, and aluminum carbonate.

[0088] The above transition metal chloride is a compound composed of a transition metal and chlorine (Cl), and may be one or more selected from the group consisting of nickel chloride, cobalt chloride, manganese chloride, and aluminum chloride.

[0089]

[0090] According to the present invention, the lithium-containing raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the lithium-containing raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, or Li3C6H5O7, and any one or more of these may be used. For example, the lithium-containing raw material may be Li2CO3.

[0091] According to the present invention, the ratio (M:Li) of the total number of moles (M) of transition metals included in the positive electrode active material precursor and the number of moles (Li) of lithium included in the lithium-containing raw material may be 1:1 to 1.05. That is, the positive electrode active material precursor and the lithium-containing raw material may be included in the molded body in an amount such that the ratio (M:Li) of the total number of moles (M) of transition metals included in the positive electrode active material precursor and the number of moles (Li) of lithium included in the lithium-containing raw material is 1:1 to 1.05. In this case, the lithium is not excessive, so the content of residual lithium, which is a byproduct after calcination, may be low.

[0092]

[0093] The molded body according to the present invention may not include a binder.

[0094]

[0095] According to the present invention, the molded body may have an average porosity of 0.30 or higher and 0.60 or lower. Specifically, the average porosity of the molded body may be 0.30 or higher, 0.35 or higher, 0.40 or higher, or 0.45 or higher, and 0.60 or lower. The average porosity is intended to indicate the extent to which pores (voids) exist in the molded body; it is the ratio of the volume occupied by pores (total volume of pores within the molded body) to the total volume of the molded body, and is a dimensionless number without units. The average porosity is used as an indicator representing the average distribution of pores within the molded body. When the average porosity of the molded body satisfies the above range, there is an advantage that gas penetrates appropriately into the interior of the molded body during the calcination reaction, allowing the calcination to occur uniformly throughout the entire molded body. Furthermore, the above average porosity range ensures that heat and gas are transferred uniformly during the calcination process, thereby allowing the crystal particles of the cathode active material to grow evenly.

[0096]

[0097] According to the present invention, the molded body may be in the form of a briquette, a cylinder, a granule, a plate, a truncated triangular cone, an elongated ellipse, a rectangular prism, or a truncated cone (a cylindrical shape with different diameters at the top and bottom). In this case, material and heat transfer are well carried out, allowing the calcination reaction for manufacturing the positive electrode active material to occur effectively, and the crystals of the positive electrode active material can be formed to a uniform size. The shape of the molded body according to the present invention may include various shapes (cylinder, truncated cone, elongated ellipse, rectangular prism, etc.) according to the embodiments.

[0098]

[0099] The molded body according to the present invention can be manufactured by appropriately adjusting conditions such as applied pressure and shear force using various processes capable of granulating or molding powder, such as a press, briquette, extrusion, spray dryer, disk pelletizer, roll compactor, low-shear wet granulator, fluidized bed granulation, twin screw wet granulation, extrusion spheronization, rotary tablet press, etc., but is not limited thereto.

[0100] For example, a molded body according to the present invention can be manufactured by the following method.

[0101] A molded body according to the present invention can be manufactured by a method for manufacturing a molded body comprising: a step of preparing a mixture by mixing the above-described positive active material precursor and a lithium-containing raw material; and a step of taking a certain amount of the mixture, introducing it into a molding device, and compression molding.

[0102] The molding device described above may be any one of a rotary tablet press, a general press, or a briquette device, and the molding method may be single-shot or continuous. The force or pressure applied during molding may be set within a range that ensures the shape stability of the molded body and reaction uniformity in the subsequent firing process. For example, the force or pressure applied during molding may be in the range of approximately 0.1 to 6 tonf in the case of press molding, and the average linear pressure may be in the range of approximately 8.5 to 9.5 ton / cm in the case of briquette molding. The pressure range is intended to prevent the mixture from becoming excessively densified or, conversely, to prevent the mechanical strength of the molded body from becoming insufficient. The shape of the molded body is not particularly limited and may be, for example, a truncated cone, a cylinder, an elongated ellipse, or a rectangular prism. In addition, the size of the molded body may also be adjusted according to the molding device and purpose, but is preferably set within a range that allows for uniform heat transfer during firing. The molded body manufactured in this manner may be provided to a subsequent firing process and used for manufacturing a positive electrode active material.

[0103]

[0104] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0105]

[0106] Examples and Comparative Examples

[0107] Example 1

[0108] Complex transition metal hydroxide in the form of secondary particles formed by the aggregation of tens to hundreds of primary particles (Composition: Ni 0.62 Co 0.05 Mn 0.33 (OH)2, D 50A mixture was prepared by mixing Li2CO3 and (2㎛) and Li2CO3 such that the ratio of the number of moles of lithium (Li) contained in Li2CO3 to the total number of moles of transition metal (Ni+Co+Mn) contained in the complex transition metal hydroxide ((Ni+Co+Mn):Li) was 1:1.05.

[0109] 200g of the above mixture was fed into a rotary tablet press and compressed with a force of 0.1 to 1 tonf to produce a molded body in the shape of a truncated cone (diameter of one base: 5 to 10 mm, diameter of the other base: 8 mm, height: 7 to 10 mm).

[0110] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0111]

[0112] Example 2

[0113] Complex transition metal hydroxide in the form of secondary particles formed by the aggregation of tens to hundreds of primary particles (Composition: Ni 0.62 Co 0.05 Mn 0.33 (OH)2, D 50 A mixture was prepared by mixing Li2CO3 and (2㎛) and Li2CO3 such that the ratio of the number of moles of lithium (Li) contained in Li2CO3 to the total number of moles of transition metal (Ni+Co+Mn) contained in the complex transition metal hydroxide ((Ni+Co+Mn):Li) was 1:1.05.

[0114] 180g of the above mixture was compressed using a press with a force of 1 to 1.5 tonf to produce a cylindrical molded body (diameter: 15mm, height: 5 to 10mm).

[0115] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0116]

[0117] Example 3

[0118] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0119] A molded body in the shape of a long elliptic (width: 20~25cm, length: 20~25cm, height: 8~15mm) was produced by molding 100g of the above mixture using a briquette device under conditions of an average linear pressure of 8.92 ton / cm.

[0120] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0121]

[0122] Example 4

[0123] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0124] A molded body in the shape of a long elliptic (width: 20~25cm, length: 20~25cm, height: 8~15mm) was produced by molding 100g of the above mixture using a briquette device under conditions of an average linear pressure of 8.72 ton / cm.

[0125] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0126]

[0127] Example 5

[0128] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0129] A molded body in the shape of a long elliptic (width: 20~25cm, length: 20~25cm, height: 8~15mm) was produced by molding 270g of the above mixture using a briquette device under conditions of an average linear pressure of 8.8 ton / cm.

[0130] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0131]

[0132] Example 6

[0133] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0134] 160g of the above mixture was compressed using a press with a force of 6 tonf to produce a molded body in the shape of a rectangular prism (width: 50mm, length: 50mm, height: 2~3mm).

[0135] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0136]

[0137] Comparative Example 1

[0138] After feeding 200g of the mixture prepared in Example 1 into a hopper, a press was operated with a force of 2.5 tonf to produce a plurality of molded bodies. For reference, when molding is performed using a hopper, a plurality of small molded bodies are formed randomly.

[0139] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0140]

[0141] Comparative Example 2

[0142] The mixture (in powder form) prepared in Example 1 was placed into an alumina circular crucible (Φ75 mm), and then calcined at a temperature of 850 to 960°C for 16 hours in an atmospheric environment to produce an anode active material. That is, the anode active material was produced by calcining the mixture directly in powder form without a separate molding process.

[0143]

[0144] Comparative Example 3

[0145] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0146] A molded body in the shape of a long elliptic (width: 40 cm, length: 25 cm, height: 10~16 mm) was produced by molding 100 g of the above mixture using a briquette device under conditions of an average linear pressure of 10.2 ton / cm.

[0147] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0148]

[0149] Comparative Example 4

[0150] Ni(OH)2, Co(OH)2, and Mn3O4 were mixed so that the molar ratio of Ni:Co:Mn was 62:6:32, and Li2CO3 was added so that the ratio of the molar amount of lithium (Li) to the total molar amount of transition metals (Ni+Co+Mn) ((Ni+Co+Mn):Li) was 1:1.05 to prepare a mixture.

[0151] 150g of the above mixture was compressed using a press with a force of 2 tonf or more to produce a cylindrical molded body (diameter: 15mm, height: 5~10mm).

[0152] After placing the above-mentioned molded body into an alumina circular crucible (Φ75mm), the positive electrode active material was prepared by firing it at a temperature of 850 to 960°C for 16 hours in an atmospheric environment.

[0153]

[0154] Experimental Example

[0155] Experimental Example 1: Load Analysis at the Time of Molded Body Fracture

[0156] Using a universal testing machine, the load measured when the sample is destroyed (fracture occurs) by the compressive load was determined when a 10 kN load cell was compressed as a free load on the molded body prepared in the examples and comparative examples, and this was used as the load at the time of destruction and is shown in Table 1 below.

[0157]

[0158] Experimental Example 2: Analysis of Thermal Conductivity of Molded Body

[0159] The thermal conductivity of the molded bodies prepared in the examples and comparative examples was analyzed using Netzsch’s LFA 467 equipment, and the results are shown in Table 1 below. To measure thermal conductivity, the molded bodies were processed to fit the measurement specimens, thinly coated with carbon powder, and raised to a temperature pre-set in the LFA 467 equipment to measure the thermal conductivity.

[0160]

[0161] Experimental Example 3: Analysis of Porosity of Molded Body

[0162] Hundreds of 2D scanned images were acquired at intervals of 50 to 100 nm using a nanoscale 3D X-ray microscope (hereinafter XRM) based micro-CT. Subsequently, through data analysis, the average porosity was measured by distinguishing between the pore region and the solid (cathode material) region within the molded body (cathode material and pores). Specifically, among the acquired images, pore information measured at unit heights of 100 nm intervals was accumulated to calculate the pore volume in unit cells (1 to 5 μm), and after summing these to obtain the total volume of the pores, the average porosity was calculated as the ratio of the pore volume to the total volume of the molded body.

[0163]

[0164] For reference, since Comparative Example 2 did not manufacture a molded body, the evaluation was performed on a mixture in powder form.

[0165]

[0166] Load at fracture (N) Thermal conductivity (W / (m·K)) Average porosity Example 1 60.35 0.57 Example 2 104 70.41 0.49 Example 3 119 0.90 0.37 Example 47 90.90 0.37 Example 5 106 0.87 0.38 Example 63 68 0.77 0.43 Comparative Example 179 810.47 0.43 Comparative Example 24 or less--Comparative Example 3 107 01.15 0.34 Comparative Example 445 330.84 0.40

[0167] Referring to Table 1 above, Comparative Example 2 is in a powder state, so it is unnecessary to evaluate the powder properties and battery performance as a molded body; therefore, the evaluation of residual lithium in Experimental Example 4 and the evaluation of battery performance in Experimental Example 5 below were not performed.

[0168]

[0169] Experimental Example 4: Evaluation of Residual Lithium

[0170] The cathode active material prepared in the examples and comparative examples was ground using a roll mill or a jet mill to produce a powder with a particle diameter of 1 mm or less. Subsequently, 5 g of the powder was taken, added to 100 ml of distilled water, and stirred for 5 minutes to obtain a filtrate.

[0171] The residual lithium content was measured by using a lithium ion titration device from Metrohm on the above liquid and titrating the lithium ions with a standard 0.1N hydrochloric acid solution.

[0172]

[0173] Classification Residual Lithium Content (wt%) Example 10.41 Example 20.56 Example 30.41 Example 40.52 Example 50.58 Example 60.40 Comparative Example 10.56 Comparative Example 30.72 Comparative Example 40.90

[0174] In powder properties, when the residual lithium content is less than 0.70 wt%, specifically 0.65 wt% or less, 0.60 wt% or less, or 0.58 wt% or less, the performance of the cathode active material is excellent, whereas when the residual lithium content is 0.70 wt% or more, the performance of the cathode active material is judged to be inferior. Accordingly, the battery performance evaluation of Experimental Example 5 below was not performed for Examples 3 to 6 and Comparative Examples 3 to 4.

[0175] Meanwhile, Comparative Examples 3 and 4 have a residual lithium content of 0.70 wt% or higher, so there is a high possibility that gas will be generated by the reaction between the electrolyte and the residual lithium, and there is a concern about battery expansion as a result.

[0176] In Tables 1 and 2 above, Comparative Example 4 has a load at fracture of 4533 N and an average porosity of 0.40, which is lower than the average porosity of Examples 4 and 5. However, the reason the residual lithium content of Comparative Example 4 is higher than that of Examples 4 and 5 is due to the difference in the molding method. In the case of the Press (up-down compression) molding method, the difference in porosity between the surface and the interior of the molded body can be significant, ranging from approximately 0.05 to 0.15. On the other hand, since the briquette is molded by a pre-compression method, the difference in porosity between the surface and the interior is relatively small. For this reason, although Comparative Example 4, manufactured by the Press method, has a high average porosity, the non-uniformity of the internal pores (relatively low porosity on the surface) makes gas exchange unfavorable, so the calcination reaction does not proceed well, and the residual lithium was measured to be relatively high.

[0177]

[0178] Experimental Example 5: Battery Performance Evaluation

[0179] A positive electrode slurry was prepared by mixing the positive electrode active materials prepared in the examples and comparative examples, FX35 conductive material, and polyvinylidene fluoride (PVDF) binder in a ratio of 95:3:2 in N-methylpyrrolidone (NMP) solvent. The positive electrode slurry was spread widely on an aluminum foil, dried at 130°C for at least 10 minutes, and rolled to produce a positive electrode.

[0180] A lithium metal electrode was used as the negative electrode, and an electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes. After placing the electrode assembly inside a battery case, an electrolyte was injected into the case to manufacture a half-cell. At this time, the electrolyte was prepared by dissolving 1.0 M LiPF6 in an organic solvent mixed with ethylene carbonate (EC):ethyl methyl carbonate (EMC):diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0181] For each half-cell manufactured as described above, the initial charge capacity and initial discharge capacity were measured and the initial efficiency was calculated and shown in Table 3 below while charging at 25°C in CC-CV mode at 0.1C until it reached 4.4V and discharging at a constant current of 0.1C until it reached 2.5V. For reference, the initial efficiency value is the percentage of the initial discharge capacity relative to the initial charge capacity.

[0182] Also, the initial resistance is R=(V 60 -V0) / I 60 , where subscript 0 is the value at 0 seconds, 60 is the value at 60 seconds, V: voltage, I: current.

[0183] Classification Initial Charge Capacity (mAh / g) Initial Discharge Capacity (mAh / g) Initial Efficiency (%) Initial Resistance (Ω) Example 1 220.7193.287.546.1 Example 2 219.6194.388.546.2 Comparative Example 1 219.5192.987.863.3

[0184] Referring to Table 3, it can be seen that a battery containing a positive active material prepared from the molded body of Example 1 according to the present invention has superior initial charge / discharge capacity and significantly lower initial resistance compared to a battery containing a positive active material prepared from the molded body of Comparative Example 1. In addition, it can be seen that a battery containing a positive active material prepared from the molded body of Example 2 according to the present invention has superior initial efficiency and significantly lower initial resistance compared to a battery containing a positive active material prepared from the molded body of Comparative Example 1.

[0185] That is, it can be confirmed that the molded bodies of Examples 1 and 2 according to the present invention allow reaction gas to penetrate relatively easily into the molded bodies, thereby enabling the easy mass production of cathode active materials having uniform physical properties with improved performance.

[0186]

[0187] According to the present invention, the positive active material manufactured as a molded body of the embodiments maintains uniform powder properties such as load, thermal conductivity, and porosity upon fracture, so the contact resistance between active materials is low and the penetration of the electrolyte is uniform during battery assembly, thereby improving the initial charge / discharge capacity, initial efficiency, and initial resistance of the battery.

[0188] In addition, since the residual lithium content in the powder is maintained at less than 0.70 wt%, the possibility of gas generation due to reaction with the electrolyte is low, thereby minimizing battery expansion and safety issues.

[0189] Furthermore, by optimizing the press and sintering conditions to manufacture the molded body, powder handling is facilitated during the slurry preparation and electrode coating processes after grinding, thereby ensuring manufacturing process efficiency suitable for mass production.

[0190] Consequently, the molded body according to the present invention provides a positive electrode active material having a uniform structure and stable physical properties, thereby having the effect of facilitating the production of high-quality batteries with excellent initial battery performance and ensured safety.

Claims

1. A positive electrode active material precursor; and a lithium-containing raw material; comprising, When a 10kN load cell is compressed under free load using a Universal Testing Machine, the load measured at the time the sample fractures due to the compressive load is greater than 4N and less than or equal to 1050N, and A molded body having a thermal conductivity of 0.25 W / (m·K) or higher and 2.0 W / (m·K) or lower.

2. In Claim 1, A molded body in which the load measured when the sample is fractured by the compressive load is 5N to 1050N when a 10kN load cell is compressed as a free load using the above Universal Testing Machine.

3. In Claim 1, A molded body having a thermal conductivity of 0.30 W / (m·K) or more and 2.0 W / (m·K) or less.

4. In Claim 1, The above positive active material precursor is a molded body comprising one or more selected from complex transition metal hydroxide, complex transition metal oxide, transition metal, transition metal oxide, transition metal hydrate, transition metal hydroxide, transition metal carbonate, and transition metal chloride.

5. In Claim 1, A molded body in which the ratio (M:Li) of the total number of moles of transition metal (M) included in the above positive active material precursor and the number of moles of lithium (Li) included in the lithium-containing raw material is 1:1 to 1.

05.

6. In Claim 1, The above-mentioned molded body is a molded body that does not contain a binder.

7. In Claim 1, A molded body with an average porosity of 0.30 or higher and 0.60 or lower.

8. In Claim 1, A molded body with an average porosity of 0.45 or higher and 0.60 or lower.

9. In Claim 1, The above-mentioned molded body is a molded body in the shape of a charcoal, cylinder, granule, plate, frustum of a triangular shape, elongated ellipse, rectangular prism, or frustum of a cone.

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