Positive active material for rechargeable lithium battery, method for preparing same, and positive electrode for rechargeable lithium battery including same, rechargeable lithium battery, and all-solid-state rechargeable battery

Abstract

The present invention relates to a positive electrode active material for a rechargeable lithium battery, a method for preparing the positive electrode active material, and a positive electrode, a rechargeable lithium battery and an all-solid-state rechargeable battery including the positive electrode active material, the positive electrode active material comprising: particles containing a lithium transition metal composite oxide; and a coating layer on the surface of the particles and containing ZrO2 and Li6Zr2O7.

Description

Technical Field

[0001] The invention discloses a positive electrode active material for rechargeable lithium batteries, a method for preparing the positive electrode active material, a positive electrode for rechargeable lithium batteries including the positive electrode active material, a rechargeable lithium battery, and an all-solid-state rechargeable battery. Background Technology

[0002] Portable information devices (such as cell phones, laptops, smartphones, etc.) or electric vehicles already use rechargeable lithium batteries with high energy density and portability as their power source. Recently, research has been actively underway to use rechargeable lithium batteries with high energy density as a power source or energy storage source for hybrid vehicles or electric vehicles.

[0003] Various positive electrode active materials have been studied to realize rechargeable lithium batteries for these applications. Among them, lithium nickel oxides, lithium nickel manganese cobalt composite oxides, lithium nickel cobalt aluminum composite oxides, and lithium cobalt oxides are mainly used as positive electrode active materials. However, these positive electrode active materials exhibit structural collapse or cracking during repeated charging and discharging, thus degrading the long-term cycle life of rechargeable lithium batteries and increasing resistance, thereby exhibiting unsatisfactory capacity characteristics. Accordingly, there is a need to develop novel positive electrode active materials that ensure long-term cycle life characteristics and achieve high capacity and high energy density.

[0004] Meanwhile, due to recent reports of explosion risks in batteries using liquid electrolytes, the development of all-solid-state rechargeable batteries has been actively pursued. However, compared to liquid electrolytes, solid electrolytes have problems such as low ionic conductivity, high resistance at the interface with solid particles of the positive electrode active material in the battery, and degradation of ionic conductivity due to the formation of a depletion layer caused by solid-to-solid bonding. There is a need to develop positive electrode active materials that can be used with these solid electrolytes, and there is also a need to develop positive electrode active materials that can improve the overall performance of all-solid-state rechargeable batteries (including capacity characteristics and long cycle life characteristics). Summary of the Invention

[0005] [Technical Issues]

[0006] The structural stability and ionic conductivity of the positive electrode active material are improved by coating its surface, and large-scale production is achieved through a dry coating method that does not use organic solvents. In batteries using solid electrolytes, the depletion layer problem between solid particles is solved, and the interface problem is addressed by suppressing the reaction between the positive electrode active material and the solid electrolyte. The capacity and cycle life characteristics of rechargeable lithium batteries are improved.

[0007] [Technical Solution]

[0008] In an embodiment, the positive electrode active material for a rechargeable lithium battery includes: particles containing a lithium transition metal composite oxide; and a coating located on the surface of the particles and containing ZrO2 and Li6Zr2O7.

[0009] In one embodiment, the method for preparing the positive electrode active material for a rechargeable lithium battery includes: dry mixing 100 molar parts of particles containing lithium transition metal composite oxide and 0.1 to 0.6 molar parts of zirconium raw material, and heat-treating the mixture at 420°C to 580°C.

[0010] In one embodiment, a positive electrode for a rechargeable lithium battery is provided, comprising a positive electrode active material.

[0011] In one embodiment, a rechargeable lithium battery is provided, comprising a positive electrode, a negative electrode, and an electrolyte.

[0012] In one embodiment, the all-solid-state rechargeable battery includes a positive electrode and a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode.

[0013] [Beneficial Effects]

[0014] According to the embodiments, the positive electrode active material for rechargeable lithium batteries includes a coating of a mixed phase of ZrO2 and Li6Zr2O7, thereby improving structural stability and increasing ionic conductivity, and effectively suppressing, for example, reactions with sulfide-based solid electrolyte particles, thus improving capacity characteristics and cycle life characteristics.

[0015] The method for preparing positive electrode active material for rechargeable lithium batteries according to the embodiments employs a dry coating method, which is beneficial for large-scale production and ensures the formation of a good coating with uniform thickness, thereby improving the yield and economic efficiency of the positive electrode active material, as well as its capacity characteristics and cycle life characteristics.

[0016] The positive electrode for rechargeable lithium batteries according to the embodiments, as well as the rechargeable lithium batteries and all-solid-state rechargeable batteries including the positive electrode, can achieve excellent capacity characteristics and cycle life characteristics. Attached Figure Description

[0017] Figure 1 and Figure 2 A cross-sectional view of an all-solid-state rechargeable battery according to an embodiment is shown for illustrative purposes.

[0018] Figure 3 The graph shows the initial charging capacity (gray bar graph) and initial discharging capacity (black bar graph) of the battery cells of Examples 1 to 5 and Comparative Examples 1 to 8.

[0019] Figure 4 The graph shows the initial discharge capacity (black bar graph) and capacity retention rate (dashed line graph) of the battery cells of Examples 1 to 5 and Comparative Examples 1 to 8.

[0020] Figure 5 The graph shows the capacity retention rate (i.e., lifetime characteristics) of Example 3 and Comparative Examples 3, 4, 6 and 7 based on the number of cycles.

[0021] Figure 6 The images show scanning electron microscope (SEM) images of the surfaces of large particles (left) and small particles (right) of the positive electrode active material in Example 3.

[0022] Figure 7 SEM images of the surfaces of large and small particles in Comparative Example 1.

[0023] Figure 8 SEM images of the surfaces of large and small particles in Comparative Example 3.

[0024] Figure 9 SEM images of the surfaces of large and small particles in Comparative Example 4.

[0025] Figure 10 SEM images of the surfaces of large and small particles in Comparative Example 5.

[0026] Figure 11 SEM images of the surfaces of large and small particles in Comparative Example 6.

[0027] Figure 12 The images show SEM-EDS (SEM-Energy Dispersive X-ray Spectroscopy) images of the surfaces of large particles (left) and small particles (right) of the positive electrode active material in Example 3.

[0028] Figure 13 SEM-EDS images of large and small particles in Comparative Example 1.

[0029] Figure 14 SEM-EDS images of large and small particles in Comparative Example 3.

[0030] Figure 15 SEM-EDS images of large and small particles in Comparative Example 4.

[0031] Figure 16 SEM-EDS images of large and small particles in Comparative Example 5.

[0032] Figure 17 SEM-EDS images of large and small particles in Example 6 are shown for comparison.

[0033] Figure 18 Images showing the distribution of Zr and Ni in the cross-section of small particles in the positive electrode active material of Example 4, analyzed using STEM-EDS (scanning transmission electron microscopy-EDS).

[0034] Figure 19 This is an HRTEM (High Resolution Transmission Electron Microscopy) image of the cross-section of small particles in the positive electrode active material of Example 4.

[0035] Figure 20 To Figure 19 The result of performing an IFFT (Inverse Fast Fourier Transform) on the region indicated by the square box in the image.

[0036] Figure 21 for Figure 20 Enlarged images of the ZrO2 region (left) and the Li6Zr2O7 region (right). Detailed Implementation

[0037] Specific implementations will be described in detail below so that those skilled in the art can readily implement them. However, this disclosure may be embodied in many different forms and is not to be construed as limited to the exemplary implementations set forth herein.

[0038] The terminology used herein is for descriptive purposes only and is not intended to limit the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0039] As used herein, “combinations thereof” means mixtures of components, laminates, complexes, copolymers, alloys, blends, reaction products, etc.

[0040] In this document, it should be understood that terms such as “comprising,” “including,” or “having” are intended to indicate the presence of specific features, quantities, steps, elements, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, elements, or combinations thereof.

[0041] In the accompanying drawings, for clarity, the thicknesses of layers, films, panels, areas, etc., are enlarged, and the same reference numerals are used throughout the drawings to label the same elements as in the specification. It will be understood that when an element (such as a layer, film, area, or substrate) is referred to as being "on" another element, it may be directly on the other element, or an intervening element may be present. In contrast, when an element is referred to as being "directly on" another element, no intervening element is present.

[0042] In addition, the term "layer" in this article includes not only shapes that form across the entire surface when viewed from a plan view, but also shapes that form on a portion of the surface.

[0043] The average particle size can be measured by methods well known to those skilled in the art, for example, by a particle size analyzer or by transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images. Alternatively, the average particle size value can be obtained by measuring using a dynamic light scattering method, performing data analysis, counting the number of particles for each particle size range, and calculating therefrom. Unless otherwise defined, the average particle size may mean the diameter (D50) of the particles having a cumulative volume of 50% of the particle size distribution. As used herein, unless otherwise defined, the average particle size means the diameter (D50) of the particles having a cumulative volume of 50% of the particle size distribution obtained by randomly measuring the size (diameter or major axis length) of approximately 20 particles in a scanning electron microscopy image.

[0044] In this article, "or" is not interpreted as exclusive; for example, "A or B" is interpreted as including A, B, A+B, etc.

[0045] The term "metal" is defined as encompassing common metals, transition metals, and quasi-metals (semi-metals).

[0046] Positive electrode active material

[0047] The positive electrode active material for a rechargeable lithium battery according to an embodiment includes: particles containing a lithium transition metal composite oxide; and a coating located on the surface of the particles and containing ZrO2 and Li6Zr2O7.

[0048] Here, rechargeable lithium batteries are used as a concept encompassing lithium-ion batteries using non-aqueous electrolyte solutions, semi-solid-state batteries, polymer batteries, and all-solid-state batteries. Positive electrode active materials possess advantages such as low reactivity with solid electrolytes and low interfacial resistance between solid particles, thus making them suitable for application in all-solid-state or semi-solid-state batteries. For example, the positive electrode active material could be a positive electrode active material used in all-solid-state rechargeable batteries.

[0049] coating

[0050] The coating of the positive electrode active material according to the embodiments comprises a mixed phase of ZrO2 and Li6Zr2O7. The coating may include ZrO2 with relatively high crystallinity and Li6Zr2O7 with relatively low crystallinity. The presence or absence of ZrO2 and Li6Zr2O7 can be determined, for example, by inverse FFT analysis of HRTEM images. The coating comprising ZrO2 and Li6Zr2O7 facilitates the movement of lithium ions on the surface of the positive electrode active material, improves the structural stability of the positive electrode active material, and improves the interfacial resistance by reducing reactivity with the solid electrolyte.

[0051] Here, the coating can be referred to as a buffer layer or a protective layer.

[0052] The coating may further include amorphous regions. For example, the coating may include ZrO2 crystalline phase, Li6Zr2O7 crystalline phase, and Zr-containing amorphous regions. Such a coating, while having a thin and uniform thickness, can improve the lithium-ion conductivity of the positive electrode active material and enhance the cycle life characteristics of the positive electrode active material.

[0053] The coating can be in the form of a continuous film or islands. The coating can be prepared by a dry coating method described later, and even so, the coating can be well formed on the surface of the positive electrode active material with a uniform thickness without aggregation or localization. For example, the coating can exist as a continuous and uniform film on the surface of particles containing lithium transition metal complex oxides. In this case, the capacity characteristics and cycle life characteristics of the positive electrode active material can be further improved.

[0054] The coating thickness can be 5 nm to 300 nm, for example 5 nm to 200 nm, 5 nm to 100 nm, 5 nm to 80 nm, or 10 nm to 50 nm. By using a coating with the above thickness range, the electrochemical characteristics of rechargeable lithium batteries can be improved by suppressing the increase in resistance caused by the coating and effectively protecting the positive electrode active material while improving ionic conductivity.

[0055] According to the embodiments, the coating can be formed on the surface of the positive electrode active material with a uniform thickness without localized presence or aggregation. For example, the standard deviation of the coating thickness can be less than or equal to 10% or 5% of the diameter of the positive electrode active material, and can be less than or equal to 100 nm, less than or equal to 50 nm, or less than or equal to 30 nm.

[0056] Based on 100 mol parts of particles containing lithium transition metal composite oxides, the Zr content in the coating can be 0.1 mol parts to 0.6 mol parts, for example, 0.1 mol parts to 0.5 mol parts or 0.1 mol parts to 0.4 mol parts. Additionally, based on 100 wt% of the positive electrode active material, the Zr content in the coating can be 0.1 wt% to 6 wt%, for example, 0.5 wt% to 6 wt% or 1 wt% to 5.5 wt%. The Zr content in the coating can be 0.1 at% to 10 at%, for example, 0.1 at% to 8 at%, 0.1 at% to 7 at%, 0.5 at% to 6.5 at%, or 1 at% to 6 at%. When the Zr content meets the above ranges, the coating can fully protect the positive electrode active material without acting as a resistor, and can exist well on the surface of the positive electrode active material with a uniform thickness without aggregation or localized presence, thereby effectively improving cycle life characteristics without reducing the capacity of the positive electrode active material. If the Zr content is too high, the coating will become thick and act as a resistive layer, which can reduce the charge / discharge capacity of the positive electrode active material. Conversely, if the Zr content is too low, it will not fully perform its buffering function, which can lead to a deterioration in the cycle life characteristics of the positive electrode active material.

[0057] Lithium transition metal composite oxide particles

[0058] In the positive electrode active material according to the embodiments, lithium transition metal complex oxide particles refer to a core having a particle shape containing lithium transition metal complex oxide, and commonly used positive electrode active materials can be used without limitation. The lithium transition metal complex oxide particles can be compounds capable of reversibly inserting and deintercalating lithium, and may include compounds represented by any of the following chemical formulas.

[0059] Li a A 1-b X b D2(0.90≤a≤1.8, 0≤b≤0.5);

[0060] Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0061] Li a E 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05);

[0062] Lia HAVE BEEN 2-b X b O 4-c D c (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05);

[0063] Li a Ni 1-b-c Co b X c D α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.5,0<α≤2);

[0064] Li a Ni 1-b-c Co b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0065] Li a Ni 1-b-c Co b X c O 2-α T2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0066] Li a Ni 1-b-c Mr b X c D α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α≤2);

[0067] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0068] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90≤a≤1.8,0≤b≤0.5,0≤c≤0.05,0<α<2);

[0069] Li a Ni b HAVE BEENc G d O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1);

[0070] Li a Ni b Co c Mn d G e O2(0.90≤a≤1.8,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0.001≤e≤0.1);

[0071] Li a NiG b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0072] Li a CoG b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0073] Li a Mn 1-b G b O2(0.90≤a≤1.8,0.001≤b≤0.1);

[0074] Li a Mn2G b O4(0.90≤a≤1.8,0.001≤b≤0.1);

[0075] Li a Mn 1-g G g PO4(0.90≤a≤1.8,0≤g≤0.5);

[0076] QO2;QS2;LiQS2;

[0077] V2O5;LiV2O5;

[0078] LiZO2;

[0079] LiNiVO4;

[0080] Li (3-f) J2(PO4)3(0≤f≤2);

[0081] Li (3-f) Fe2(PO4)3(0≤f≤2);

[0082] Li a FePO4(0.90≤a≤1.8).

[0083] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn and their combinations; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and their combinations; D is selected from the group consisting of O, F, S, P and their combinations; E is selected from the group consisting of Co, Mn and their combinations; T is selected from the group consisting of F, S, P and their combinations; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V and their combinations; Q is selected from the group consisting of Ti, Mo, Mn and their combinations; Z is selected from the group consisting of Cr, V, Fe, Sc, Y and their combinations; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu and their combinations.

[0084] Lithium transition metal composite oxides may include, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), lithium iron phosphate oxide (LFP), or combinations thereof.

[0085] Lithium transition metal composite oxides can be, for example, lithium nickel oxides represented by chemical formula 1, lithium cobalt oxides represented by chemical formula 2, lithium iron phosphate compounds represented by chemical formula 3, or cobalt-free lithium nickel manganese oxides represented by chemical formula 4.

[0086] [Chemical Formula 1]

[0087] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0088] In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each element is independently selected from one or more elements chosen from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, and Zr, and X is selected from one or more elements chosen from the group consisting of F, P, and S.

[0089] [Chemical Formula 2]

[0090] Li a2 Co x2 M3 y2 O 2-b2 X b2

[0091] Among them, in Chemical Formula 2, 0.9 ≤ a2 ≤ 1.8, 0.7 ≤ x2 ≤ 1, 0 ≤ y2 ≤ 0.3, 0.9 ≤ x2 + y2 ≤ 1.1, and 0 ≤ b2 ≤ 0.1, M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from the group consisting of F, P, and S,

[0092] [Chemical Formula 3]

[0093] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0094] Among them, in Chemical Formula 3, 0.9 ≤ a3 ≤ 1.8, 0.6 ≤ x3 ≤ 1, 0 ≤ y3 ≤ 0.4, and 0 ≤ b3 ≤ 0.1, M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is one or more elements selected from the group consisting of F, P, and S, and

[0095] [Chemical Formula 4]

[0096] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0097] Among them, in Chemical Formula 4, 0.9 ≤ a4 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1, M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0098] For example, the lithium transition metal composite oxide may be a lithium nickel-based oxide represented by Chemical Formula 1, for example, a high-nickel-based oxide. That is, relative to 100 mol% of the metals other than lithium in the lithium transition metal composite oxide, the content of nickel may be greater than or equal to 80 mol%, or greater than or equal to 90 mol%, greater than or equal to 91 mol% or greater than or equal to 94 mol%. In Chemical Formula 1, 0.8 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.2, and 0 ≤ z1 ≤ 0.2 may be satisfied, or 0.9 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.1, and 0 ≤ z1 ≤ 0.1, or 0.91 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.09, and 0 ≤ z1 ≤ 0.09, or 0.94 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.06, and 0 ≤ z1 ≤ 0.06. For example, 0.8 ≤ x1 < 1, 0 < y1 ≤ 0.2, and 0 ≤ z1 ≤ 0.2 or 0.9 ≤ x1 < 1, 0 < y1 ≤ 0.1, and 0 ≤ z1 ≤ 0.1. The high-nickel-based oxide can achieve a high capacity, making it suitable for high-capacity, high-density rechargeable lithium batteries that are in high demand today. However, because the positive electrode active material containing the high-nickel-based oxide has a large volume change of about 8% during charging and discharging, it is difficult to maintain long-term contact with the solid electrolyte. However, by introducing a coating according to an embodiment, long-term adhesion between solid particles can be achieved while promoting the movement of lithium ions.

[0099] The average particle diameter (D50) of the particles containing the lithium transition metal composite oxide may be 1 μm to 25 μm, for example, 2 μm to 20 μm or 3 μm to 18 μm. Here, the average particle diameter means the diameter (D50) of the particle having a cumulative volume of 50% by volume in the particle size distribution obtained by randomly measuring the sizes (diameter or major axis length) of about 20 particles in a scanning electron microscope image.

[0100] The particles containing the lithium transition metal composite oxide may be in the form of secondary particles in which a plurality of primary particles are aggregated, in the form of single particles, or in the form of a mixture thereof. The secondary particles may be a polycrystal. The single particle may exist alone without grain boundaries within the particle, the single particle is composed of one particle, and may be a single particle, a monolithic structure, an integral structure, or a non-aggregated particle, where the particles do not aggregate with each other but exist as independent phases in terms of morphology, and may be represented as a single particle (integral particle, single crystal grain), for example, represented as a single crystal.

[0101] For example, particles containing lithium transition metal composite oxides may include: large particles with an average particle size of 9 μm to 25 μm; and small particles with an average particle size of 1 μm to 8 μm. In this case, based on a total of 100 wt% large and small particles, large particles may be included in an amount of 60 wt% to 95 wt%, and small particles may be included in an amount of 5 wt% to 40 wt%. For example, large particles may be included in an amount of 70 wt% to 90 wt%, and small particles may be included in an amount of 10 wt% to 30 wt%. High energy density batteries can be achieved by mixing large and small particles.

[0102] Large particles can take the form of secondary particles composed of multiple primary particles, and small particles can take the form of secondary particles composed of multiple primary particles or a single particle.

[0103] The average particle size of large particles can be 9 μm to 20 μm or 10 μm to 15 μm. The average particle size of small particles can be 1 μm to 7 μm, 1 μm to 6 μm or 2 μm to 5 μm. Here, the average particle size can be obtained by randomly measuring the size (diameter or major axis length) of about 20 particles in an electron microscope image (such as a scanning electron microscope), and then taking the diameter (D50) of the particles with a cumulative volume of 50% as the average particle size.

[0104] Method for preparing positive electrode active materials

[0105] In an embodiment, a method for preparing a positive electrode active material is provided, comprising dry mixing 100 moles of particles containing a lithium transition metal composite oxide and 0.1 to 0.6 moles of zirconium raw material, and treating the mixture at 420°C to 580°C. This method enables the preparation of the aforementioned positive electrode active material. This method is a dry coating method that does not use organic solvents or expensive coating materials and can utilize existing equipment, making it economical and environmentally friendly, and enabling large-scale production. According to the above method, a positive electrode active material having a coating containing ZrO2 and Li6Zr2O7 can be synthesized, and the coating with appropriate amount and thickness can be synthesized in a favorable form, thereby producing a positive electrode active material with improved capacity and cycle life characteristics. The positive electrode active material has low reactivity with sulfide-based solid electrolyte particles and low interfacial resistance; therefore, this positive electrode active material can be applied to all-solid-state rechargeable batteries, etc., to improve capacity characteristics, rate performance, and cycle life characteristics.

[0106] Since lithium transition metal complex oxides have already been described above, their detailed description will be omitted.

[0107] Zirconium raw materials are compounds containing elemental zirconium, and their use is unrestricted as long as they are compounds that can be dry-mixed. Zirconium raw materials may be, for example, zirconium oxides, zirconium sulfides, zirconium carbonates, zirconium hydroxides, etc., and may be, for example, zirconium oxide, zirconium sulfide, zirconium carbonate, zirconium hydroxide, or combinations thereof.

[0108] Based on 100 moles of particles containing lithium transition metal composite oxides, zirconium feedstock is mixed in amounts of 0.1 to 0.6 moles, for example, 0.1 to 0.5 moles or 0.1 to 0.4 moles. Adding zirconium feedstock within these ranges allows for the formation of a coating of appropriate quantity and thickness that adequately protects the positive electrode active material and exists on the surface of the positive electrode active material with uniform thickness, without aggregation or localized areas. If the amount of zirconium feedstock exceeds 0.6 moles, the coating becomes thicker and acts as a resistive layer, thereby reducing the charge / discharge capacity of the positive electrode active material. Conversely, if the amount of zirconium feedstock is less than 0.1 moles, it does not fully perform its buffering function, which can lead to a deterioration in the cycle life characteristics of the positive electrode active material.

[0109] For example, the zirconium raw material can be in the form of nanoparticles. The zirconium raw material is in particulate form, and the average particle size (D50) can be, for example, 10 nm to 500 nm, 10 nm to 500 nm, or 50 nm to 500 nm. For example, the zirconium raw material can be particles comprising zirconium oxide, and the average particle size (D50) can be 10 nm to 500 nm. In this case, it is advantageous to synthesize a coating of appropriate thickness.

[0110] In the method for preparing a positive electrode active material according to the embodiments, dry mixing means mixing without the use of solvents and can be understood as a solid-phase coating method. This differs from wet coating or liquid coating.

[0111] In the preparation of the positive electrode active material according to the embodiment, a coating with a uniform thickness containing a mixed phase of ZrO2 and Li6Zr2O7 can be formed by heat treatment at 420°C to 580°C after dry mixing. The heat treatment temperature can be, for example, 430°C to 570°C, 440°C to 560°C, 450°C to 550°C, or 460°C to 530°C. By heat treatment within the above temperature range, a coating with a suitable crystalline phase can be synthesized, and the coating does not act as a resistor but rather provides sufficient buffering, thereby improving the capacity characteristics and cycle life characteristics of the positive electrode active material. For example, if the heat treatment temperature is less than 420°C, the coating may not form a suitable crystalline phase and may only act as a resistor, which can degrade the capacity characteristics of the positive electrode active material. If the heat treatment temperature exceeds 580°C, the coating material may aggregate or only be partially coated, reducing the buffering effectiveness. Furthermore, zirconium can be absorbed into the positive electrode active material, failing to provide a buffering effect, and the capacity characteristics and cycle life characteristics may deteriorate.

[0112] Heat treatment can be carried out in an oxygen atmosphere, for example, for 5 to 25 hours or 10 to 20 hours. Under these conditions, a good coating can be formed.

[0113] In this embodiment, when the particles containing lithium transition metal composite oxide and the zirconium raw material are dry-mixed, the lithium raw material can be mixed together. The lithium raw material is a lithium-containing compound, and its use is unrestricted as long as it can be dry-mixed. The lithium raw material can be, for example, Li₂CO₃, LiOH, its hydrates, or combinations thereof. Based on 1 mole of zirconium raw material, the lithium raw material can be mixed in amounts greater than 1 mole and less than or equal to 4 moles, for example, greater than 1 mole and less than or equal to 3 moles, or greater than 2 moles and less than or equal to 4 moles. When the lithium raw material is mixed together and heat-treated, it is beneficial to form lithium zirconium oxide (e.g., Li₆Zr₂O₇ crystalline phase) in the coating, increasing lithium-ion conductivity and obtaining a coating of appropriate thickness in a good form.

[0114] positive electrode

[0115] In one embodiment, a positive electrode for a rechargeable lithium battery is provided, comprising the aforementioned positive electrode active material or a positive electrode active material prepared according to the aforementioned method. The positive electrode for the rechargeable lithium battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer comprises the aforementioned positive electrode active material and may further include a binder and / or a conductive material.

[0116] The binder improves the adhesion properties between the positive electrode active material particles and between the positive electrode active material particles and the current collector. Examples of binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited to these.

[0117] Based on the total weight of the positive electrode active material layer, the amount of binder in the positive electrode active material layer can be approximately 1 wt% to 5 wt%.

[0118] Conductive materials are any materials used to impart electrical conductivity to electrodes without causing chemical changes and conducting electrons that can be used in batteries. Examples may include: carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metallic materials, including copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0119] Based on the total weight of the positive electrode active material layer, the amount of conductive material in the positive electrode active material layer can be 1wt% to 5wt%.

[0120] The positive electrode current collector can be aluminum foil, but is not limited to this.

[0121] Meanwhile, the positive electrode according to the embodiment can be, for example, a positive electrode used in all-solid-state rechargeable batteries. The aforementioned positive electrode active material has a buffering coating on its surface, thereby reducing reactivity with solid electrolytes (especially sulfide-based solid electrolytes), solving problems that occur at the interface of solid particles, and improving the capacity characteristics and cycle life characteristics of all-solid-state rechargeable batteries.

[0122] The positive electrode for an all-solid-state rechargeable battery includes the aforementioned positive electrode active material, optionally including binders, conductive materials, etc., and may further include a solid electrolyte.

[0123] solid electrolyte

[0124] Solid electrolytes can be inorganic solid electrolytes, such as sulfide solid electrolytes or oxide solid electrolytes.

[0125] In this embodiment, the solid electrolyte may be a sulfide-based solid electrolyte with excellent ionic conductivity. Sulfide-based solid electrolyte particles may include, for example, Li₂S-P₂S₅, Li₂S-P₂S₅-LiX (where X is a halogen element, such as I or Cl), Li₂S-P₂S₅-Li₂O, Li₂S-P₂S₅-Li₂O-LiI, Li₂S-SiS₂, Li₂S-SiS₂-LiI, Li₂S-SiS₂-LiBr, Li₂S-SiS₂-LiCl, Li₂S-SiS₂-B₂S₃-LiI, Li₂S-SiS₂-P₂S₅-LiI, Li₂S-B₂S₃, and Li₂S-P₂S₅-Z. m S n (where m and n are integers and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each integers and M is P, Si, Ge, B, Al, Ga, or In) or a combination thereof.

[0126] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li₂S and P₂S₅ in a molar ratio of 50:50–90:10 or 50:50–80:20 and optionally by heat treatment. Within the above mixing ratio range, sulfide-based solid electrolytes with excellent ionic conductivity can be prepared. Ionic conductivity can be further improved by adding SiS₂, GeS₂, B₂S₃, etc., as other components.

[0127] Mechanical grinding or solution processing can be used as mixing methods for sulfur-containing raw materials used in the preparation of sulfide-based solid electrolytes. Mechanical grinding involves mixing the raw materials by placing them in a ball mill reactor and vigorously stirring them to refine them into particles. Solution processing can be used to obtain a solid electrolyte as a precipitate by mixing the raw materials in a solvent. Furthermore, heat treatment after mixing can result in more robust solid electrolyte crystals and improved ionic conductivity. For example, sulfide-based solid electrolytes can be prepared by mixing sulfur-containing raw materials and subjecting them to two or more heat treatments. In this case, sulfide-based solid electrolytes with high ionic conductivity and robustness can be prepared.

[0128] According to the embodiments, sulfide-based solid electrolyte particles can be prepared, for example, by a first heat treatment and a second heat treatment. The first heat treatment involves mixing sulfur-containing raw materials and calcining them at 120°C to 350°C, and the second heat treatment involves mixing the results of the first heat treatment and calcining them at 350°C to 800°C. The first and second heat treatments can be carried out in an inert gas atmosphere or a nitrogen atmosphere, respectively. The first heat treatment can be carried out for 1 hour to 10 hours, and the second heat treatment can be carried out for 5 hours to 20 hours. The fine raw materials can be ground by the first heat treatment, and the final solid electrolyte can be synthesized by the second heat treatment. By performing two or more such heat treatments, a sulfide-based solid electrolyte with high ionic conductivity and high performance can be obtained, and this solid electrolyte is suitable for large-scale production. The temperature of the first heat treatment can be, for example, 150°C to 330°C or 200°C to 300°C, and the temperature of the second heat treatment can be, for example, 380°C to 700°C or 400°C to 600°C.

[0129] For example, sulfide-based solid electrolyte particles may include sulfide-germanium sulfides. Sulfide-germanium sulfide-based solid electrolyte particles may have a density close to 10. -4 ~10 -2a high ionic conductivity in the range of S / cm, which is the ionic conductivity of a conventional liquid electrolyte at room temperature, and can form a tight bond between the positive electrode active material and the solid electrolyte without causing a reduction in ionic conductivity, and further, form a tight interface between the electrode layer and the solid electrolyte layer. A all-solid-state rechargeable battery including the same can have improved battery performance such as rate performance, Coulomb efficiency, and cycle life characteristics.

[0130] The argyrodite-type sulfide solid electrolyte particles may include, for example, a compound represented by Chemical Formula 11.

[0131] [Chemical Formula 11]

[0132] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0133] In Chemical Formula 11, 4 ≤ a ≤ 8, M 1 is Mg, Cu, Ag, or a combination thereof, 0 ≤ b < 0.5, M 2 is Na, K, or a combination thereof, 0 ≤ c < 0.5, M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, 0 < d < 4, 0 ≤ e < 1, M 4 is O, SO n or a combination thereof, 1.5 ≤ n ≤ 5, 3 ≤ f ≤ 12, 0 ≤ g < 2, X is F, Cl, Br, I, or a combination thereof, and 0 ≤ h ≤ 2.

[0134] For example, a halogen element (X) may have to be included in Chemical Formula 11, and in that case, it may be expressed as 0 < h ≤ 2. For example, the M 1 element may have to be included in Chemical Formula 11, and in that case, it may be expressed as 0 < b < 0.5. In Chemical Formula 11, M 3 can be understood as an element substituting for P and can be 0 < e < 1. In Chemical Formula 11, M 4 substitutes for S, for example, can be 0 < g < 2, and f (the proportion of S) can be, for example, 3 ≤ f ≤ 7. If M 4 is SO n , then SO n can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, SO5, etc., and can be, for example, SO4.

[0135] For example, in chemical formula 11, a+b+c+h=7, d+e=1, and f+g+h=6.

[0136] As an example, sulfide solid electrolyte particles of the sulfide type, such as silver-germanium sulfide, may include Li3PS4 and Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 Li 5.75 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 PS 4.75 Cl 1.25 、(Li 5.72 Cu 0.03 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 、(Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 、(Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 Or combinations thereof, but not limited to these.

[0137] A sulfide-based solid electrolyte of sulfide type can be prepared, for example, by mixing lithium sulfide and phosphorus sulfide, and optionally lithium halide. Heat treatment can be performed after mixing. The heat treatment may include, for example, two or more heat treatment steps. A method for preparing a sulfide-based solid electrolyte of sulfide type can include, for example, a first heat treatment and a second heat treatment, in which the raw materials are mixed and calcined at 120°C to 350°C, and in the second heat treatment, the result of the first heat treatment is mixed again and calcined at 350°C to 800°C.

[0138] The average particle size (D50) of sulfide-based solid electrolyte particles can be, for example, 0.1 μm to 5.0 μm or 0.1 μm to 3.0 μm, and can be small particles of 0.1 μm to 1.9 μm or large particles of 2.0 μm to 5.0 μm. Sulfide-based solid electrolyte particles can be a mixture of small particles with an average particle size of 0.1 μm to 1.9 μm and large particles with an average particle size of 2.0 μm to 5.0 μm. The average particle size of sulfide-based solid electrolyte particles can be measured using electron microscopy images, and for example, the particle size distribution can be obtained by measuring the size (diameter or major axis length) of about 20 particles in a scanning electron microscope image, and D50 can be calculated from this.

[0139] Besides sulfide-based materials, solid electrolytes can include oxide-based inorganic solid electrolytes. Oxide-based inorganic solid electrolytes can include, for example, Li... 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2,0≤y<3)、BaTiO3、Pb(Zr,Ti)O3(PZT)、Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1,0≤y<1), PB(Mg3Nb 2 / 3 The following are listed: PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3,0 <x<2,0<y<3)、Li 1+x+y (Al,Ga) x(Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), lanthanum lithium titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li2O, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2 - type ceramics, garnet - type ceramics Li 3+x La3M2O 12 (M = Te, Nb or Zr; x is an integer from 1 to 10) or a mixture thereof.

[0140] The solid electrolyte may be in the form of particles, and the average particle size (D50) may be less than or equal to 5.0 μm, for example, 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm or 0.5 μm to 1.0 μm. Such a solid electrolyte can effectively penetrate between the positive electrode active materials, and has excellent contact with the positive electrode active materials and excellent connectivity between the solid electrolyte particles.

[0141] Based on 100 wt% of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt% or 10 wt% to 20 wt%.

[0142] In addition, in the positive electrode active material layer, based on the total of 100 wt% of the positive electrode active material and the solid electrolyte, 65 wt% to 99 wt% of the positive electrode active material and 1 wt% to 35 wt% of the solid electrolyte may be included. For example, 80 wt% to 90 wt% of the positive electrode active material and 10 wt% to 20 wt% of the solid electrolyte may be included. If the solid electrolyte is included in the positive electrode in this amount, the efficiency characteristics and cycle life characteristics of the all - solid - state battery can be improved without reducing the capacity.

[0143] Rechargeable lithium batteries

[0144] In an embodiment, the rechargeable lithium battery includes the aforementioned positive electrode containing the positive electrode active material, a negative electrode, and an electrolyte. Herein, the rechargeable lithium battery can be understood in the conventional concept, such as a lithium - ion battery using a non - aqueous electrolyte solution, a lithium - metal battery using lithium metal as the negative electrode, and an all - solid - state rechargeable battery having a solid electrolyte layer between the positive electrode and the negative electrode.

[0145] Lithium-ion batteries

[0146] In the embodiments, a lithium-ion battery is described that uses a non-aqueous electrolyte solution as the electrolyte while applying the aforementioned positive electrode active material.

[0147] A rechargeable lithium battery according to an embodiment may include a battery cell, a battery container containing the battery cell, and a sealing member for sealing the battery container. The battery cell includes a positive electrode, a negative electrode facing the positive electrode, a separator between the positive electrode and the negative electrode, and an electrolyte impregnating the positive electrode, the negative electrode, and the separator.

[0148] negative electrode

[0149] The negative electrode for a rechargeable lithium battery includes a current collector and a layer of negative electrode active material on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder and / or a conductive material.

[0150] Negative electrode active materials include materials that can reversibly insert / deintercalate lithium ions, lithium metal, lithium metal alloys, materials that can be doped / dedoped with lithium, or transition metal oxides.

[0151] Materials that can reversibly insert / deintercalate lithium ions can include, for example, crystalline carbon, amorphous carbon, or combinations thereof as carbon-based negative electrode active materials. Crystalline carbon can be amorphous or in the form of flakes, sheets, spheres, or fibers, such as natural or artificial graphite. Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0152] Lithium metal alloys include alloys of lithium with metals selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0153] Materials capable of doping / dedoping lithium can be either Si-based or Sn-based negative electrode active materials. Si-based negative electrode active materials may include silicon, silicon-carbon composites, and SiO₂. x(0 < x < 2), Si-Q alloy (where Q is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, Group 15 element, Group 16 element, transition metal, rare earth element, and combinations thereof, but not Si), and the Sn-based negative electrode active material may include Sn, SnO2, Sn-R alloy (where R is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, Group 15 element, Group 16 element, transition metal, rare earth element, and combinations thereof, but not Sn). At least one of these materials may be mixed with SiO2. The element Q and the element R may be selected from the group consisting of: Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0154] As an example, the negative electrode active material may include silicon-carbon composite particles. The average particle size (D50) of the silicon-carbon composite particles may be, for example, 0.5 μm to 20 μm. Based on 100 wt% of the silicon-carbon composite particles, silicon may be included in an amount of 10 wt% to 60 wt% and carbon may be included in an amount of 40 wt% to 90 wt%. For example, the silicon-carbon composite particles may include: a core including silicon particles; and a carbon coating located on the surface of the core. The average particle size (D50) of the silicon particles in the core may be 10 nm to 1 μm or 10 nm to 200 nm. The silicon particles may exist as elemental silicon, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon may be represented by SiO x (0 < x < 2). Additionally, the thickness of the carbon coating may be about 5 nm to 100 nm.

[0155] As an example, the silicon-carbon composite particles may include: a core including silicon particles and crystalline carbon; and a carbon coating located on the surface of the core and including amorphous carbon. For example, in the silicon-carbon composite particles, amorphous carbon may not be present in the core but only in the carbon coating. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof, and the amorphous carbon may be formed from coal tar pitch, mesophase pitch, petroleum pitch, coal oil, heavy petroleum, or polymer resins (phenolic resin, furan resin, polyimide). At this time, based on 100 wt% of the silicon-carbon composite particles, the amount of crystalline carbon may be 10 wt% to 70 wt%, and the amount of amorphous carbon may be 20 wt% to 40 wt%.

[0156] In the silicon-carbon composite particles, the core may include pores in the center. The radius of the pores may be 30% to 50% of the radius of the silicon-carbon composite particles.

[0157] Silicon-carbon composite particles effectively suppress problems such as volume expansion, structural collapse, or particle pulverization due to charging and discharging, prevent the interruption of conductive paths, achieve high capacity and high efficiency, and are advantageous for use in high-voltage or fast-charging conditions.

[0158] Si-based or Sn-based negative electrode active materials can be mixed with carbon-based negative electrode active materials. When Si-based or Sn-based negative electrode active materials are mixed with carbon-based negative electrode active materials and used, the mixing ratio can be 1:99 to 90:10 by weight.

[0159] Based on a 100wt% negative electrode active material layer, the amount of negative electrode active material can be 95wt% to 99wt%.

[0160] In an embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. Based on 100 wt% of the negative electrode active material layer, the amount of binder in the negative electrode active material layer may be 1 wt% to 5 wt%. Alternatively, when further including a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0161] The binder is used to bond the negative electrode active material particles well together and also to bond the negative electrode active material to the current collector. The binder may be a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0162] Water-insoluble adhesives may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, ethylene propylene copolymers, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0163] Water-soluble adhesives may include rubber adhesives or polymeric resin adhesives. Rubber adhesives may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. Polymeric resin adhesives may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0164] When a water-soluble binder is used as a negative electrode binder, it may further include a cellulose-based compound capable of imparting viscosity as a thickener. As a cellulose-based compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or their alkali metal salts may be mixed and used. The alkali metal may be Na, K, or Li. Based on 100 parts by weight of the negative electrode active material, the amount of thickener used may be from 0.1 parts by weight to 3 parts by weight.

[0165] This includes conductive materials to provide electrode conductivity, and any conductive material may be used as a conductive material unless it causes a chemical change; and examples of conductive materials include: carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metallic materials, including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0166] The negative electrode current collector may include one selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0167] electrolytes

[0168] Electrolytes include non-aqueous organic solvents and lithium salts.

[0169] Non-aqueous organic solvents are used as media for transporting ions involved in the electrochemical reactions of a battery. Non-aqueous organic solvents can be carbonates, esters, ethers, ketones, alcohols, or aprotic solvents. Carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butyl carbonate (BC), etc. Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolactone, valerate, mevalonolactone, caprolactone, etc. Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, tetrahydrofuran, etc., and ketone solvents may include cyclohexanone, etc. In addition, alcohol solvents may be ethanol, isopropanol, etc., and aprotic solvents may be nitriles (such as R-CN (where R is a C2 to C20 straight chain, branched chain or cyclic hydrocarbon group, and may include double bond, aromatic ring or ether bond)), amides (such as dimethylformamide), dioxolane (such as 1,3-dioxolane), sulfolane, etc.

[0170] Non-aqueous organic solvents can be used alone or in combination of one or more, and when used in combination of one or more, the mixing ratio can be appropriately adjusted according to the desired battery performance, as is widely understood by those skilled in the art.

[0171] Alternatively, in the case of carbonate solvents, a mixture of cyclic carbonates and chain carbonates can be used. In this case, when cyclic carbonates and chain carbonates are mixed in a volume ratio of about 1:1 to about 1:9, the electrolyte exhibits excellent performance.

[0172] In addition to carbonate solvents, non-aqueous organic solvents may further include aromatic hydrocarbon organic solvents. In this case, carbonate solvents and aromatic hydrocarbon organic solvents may be mixed in a volume ratio of about 1:1 to about 30:1.

[0173] Aromatic hydrocarbon solvents can be aromatic hydrocarbon compounds represented by chemical formula I.

[0174] [Chemical Formula I]

[0175]

[0176] In chemical formula I, R 4 ~R 9 They may be the same or different, and are selected from hydrogen, halogens, C1-C10 alkyl groups, C1-C10 haloalkyl groups and combinations thereof.

[0177] Specific examples of aromatic hydrocarbon solvents include benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-trifluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4-triiodobenzene, toluene, and fluorotoluene. 2,3-Difluorotoluene, 2,4-Difluorotoluene, 2,5-Difluorotoluene, 2,3,4-Trifluorotoluene, 2,3,5-Trifluorotoluene, Chlorotoluene, 2,3-Dichlorotoluene, 2,4-Dichlorotoluene, 2,5-Dichlorotoluene, 2,3,4-Trichlorotoluene, 2,3,5-Trichlorotoluene, Iodotoluene, 2,3-Diiodotoluene, 2,4-Diiodotoluene, 2,5-Diiodotoluene, 2,3,4-Triiodotoluene, 2,3,5-Triiodotoluene, Xylene, or combinations thereof.

[0178] The electrolyte may further include vinylene carbonate or ethylene carbonate compounds represented by Formula II in order to improve the cycle life of the battery.

[0179] [Chemical Formula II]

[0180]

[0181] In chemical formula II, R 10 and R 11 The same or different, and selected from hydrogen, halogen, cyano, nitro and fluorinated C1 to C5 alkyl groups, under the condition that R 10 and R 11 At least one of them is a halogen, cyano, nitro, or fluorinated C1-C5 alkyl group, and R 10 and R 11 They are not both hydrogen.

[0182] Examples of ethylene carbonate compounds may be difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, brominated ethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, or fluoroethylene carbonate. The amount of additives used to improve cycle life may be used within appropriate limits.

[0183] Lithium salts dissolved in non-organic solvents supply lithium ions in the battery, ensuring basic operation of the rechargeable lithium battery and improving lithium ion transport between the positive and negative electrodes.

[0184] Lithium salts can be used without type restriction and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or combinations thereof.

[0185] Lithium salts can be used in concentration ranges from 0.1M to 2.0M. If lithium salts are included in the above concentration range, the electrolyte can exhibit excellent performance and lithium-ion mobility due to optimal electrolyte conductivity and viscosity.

[0186] diaphragm

[0187] The separator separates the positive and negative electrodes and provides a transport channel for lithium ions, and can be any commonly used separator in lithium-ion batteries. In other words, the separator can have low ion transport resistance and excellent impregnation with electrolytes. For example, the separator can include glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene, or combinations thereof, and can be in the form of non-woven or woven fabrics. For example, in lithium-ion batteries, polyolefin polymer separators, such as polyethylene and polypropylene, are primarily used. To ensure heat resistance or mechanical strength, coated separators including ceramic components or polymer materials can be used. Optionally, the separator can have a single-layer or multi-layer structure.

[0188] All-solid-state rechargeable batteries

[0189] In one embodiment, an all-solid-state rechargeable battery is provided, which includes the aforementioned positive electrode and negative electrode and a solid electrolyte layer between the positive electrode and the negative electrode.

[0190] Figure 1 This is a cross-sectional view of an all-solid-state rechargeable battery according to an embodiment. (Reference) Figure 1 The all-solid-state rechargeable battery 100 may have a structure in which an electrode assembly is housed in a battery casing. In the electrode assembly, a negative electrode 400 comprising a negative electrode current collector 401 and a negative electrode active material layer 403, a solid electrolyte layer 300, and a positive electrode 200 comprising a positive electrode active material layer 203 and a positive electrode current collector 201 are stacked. The all-solid-state rechargeable battery 100 may further include at least one elastic layer 500 on the outer side of at least one of the positive electrode 200 and the negative electrode 400. Figure 1 An electrode assembly including a negative electrode 400, a solid electrolyte layer 300, and a positive electrode 200 is shown, but two or more electrode assemblies can be stacked to fabricate an all-solid-state rechargeable battery.

[0191] negative electrode

[0192] For example, the negative electrode for an all-solid-state rechargeable battery can be the same negative electrode as described for a lithium-ion battery.

[0193] Alternatively, as another example, the negative electrode for an all-solid-state rechargeable battery can be a deposition-type negative electrode, unlike the aforementioned negative electrodes. A deposition-type negative electrode does not include a negative electrode active material in the battery assembly, but rather refers to a negative electrode in which lithium metal or the like is deposited or electrodeposited on the negative electrode during battery charging, thereby serving as the negative electrode active material.

[0194] Figure 2 This is a schematic cross-sectional view of an all-solid-state rechargeable battery including a deposited negative electrode. (Reference) Figure 2The deposited negative electrode 400' may include a current collector 401 and a negative electrode coating 405 on the current collector. In an all-solid-state rechargeable battery having such a deposited negative electrode 400', initial charging begins in the absence of negative electrode active material, and during charging, high-density lithium metal is deposited or electrodeposited between the current collector 401 and the negative electrode coating 405, or deposited or electrodeposited on the negative electrode coating 405 to form a lithium metal layer 404 that can be used as a negative electrode active material. Accordingly, in an all-solid-state rechargeable battery that has been charged at least once, the deposited negative electrode 400' may include, for example, a current collector 401, a lithium metal layer 404 on the current collector, and a negative electrode coating 405 on the metal layer. The lithium metal layer 404 may be referred to as a layer in which lithium metal or the like is deposited during the charging process of the battery, and may be referred to as a metal layer, a lithium layer, a lithium electrodeposition layer, or a negative electrode active material layer.

[0195] The negative electrode coating 405 may be referred to as a lithium-ion deposition induction layer or a negative electrode catalyst layer, and may include a metal, carbon material or a combination thereof that acts as a catalyst.

[0196] The metal may be a lithium-loving metal and may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or combinations thereof, and may consist of one of these types or alloys of various types. When the metal exists in particulate form, its average particle size (D50) may be less than or equal to about 4 μm, for example, 10 nm to 4 μm.

[0197] Carbon materials can be, for example, crystalline carbon, amorphous carbon, or combinations thereof. Crystalline carbon can be, for example, natural graphite, artificial graphite, mesophase carbon microspheres, or combinations thereof. Amorphous carbon can be, for example, carbon black, activated carbon, acetylene black, superconducting acetylene black, Ketjen black, or combinations thereof.

[0198] When the negative electrode coating 405 comprises metal and carbon materials, the metal and carbon materials can be mixed, for example, in a weight ratio of 1:10 to 2:1. This effectively promotes lithium metal deposition and improves the characteristics of the all-solid-state rechargeable battery. The negative electrode coating 405 may comprise, for example, carbon materials on which a catalyst metal is loaded, or a mixture of metal particles and carbon material particles.

[0199] The negative electrode coating 405 may include, for example, metal and amorphous carbon, and in this case, lithium metal deposition can be effectively promoted.

[0200] The negative electrode coating 405 may further include a binder, and the binder may be a conductive binder. Additionally, the negative electrode coating 405 may further include conventional additives (such as fillers, dispersants, and ionic conductive agents).

[0201] The negative electrode coating 405 may have a thickness of, for example, 100 nm to 20 μm, 500 nm to 10 μm, or 1 μm to 5 μm.

[0202] The deposited negative electrode 400' may further include, for example, a thin film on the surface of the current collector (i.e., between the current collector and the negative electrode coating). The thin film may include elements capable of forming alloys with lithium. Elements capable of forming alloys with lithium may include, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., which may be used alone or in alloys of one or more. The thin film may further planarize the deposited shape of the lithium metal layer 404 and significantly improve the characteristics of the all-solid-state rechargeable battery. The thin film may be formed, for example, by vacuum deposition, sputtering, electroplating, etc. The thin film may have a thickness of, for example, 1 nm to 500 nm.

[0203] The lithium metal layer 404 may include lithium metal or a lithium alloy. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy.

[0204] The thickness of the lithium metal layer 404 can be 1μm to 500μm, 1μm to 200μm, 1μm to 100μm, or 1μm to 50μm. If the thickness of the lithium metal layer 404 is too thin, it will be difficult to perform lithium storage, and if it is too thick, it will increase the battery volume and degrade performance.

[0205] When this deposition-type negative electrode is applied, the negative electrode coating 405 can be used to protect the lithium metal layer 404 and suppress the deposition and growth of lithium dendrites. Accordingly, short circuits and capacity degradation in the all-solid-state battery can be suppressed, and cycle life characteristics can be improved.

[0206] solid electrolyte layer

[0207] The solid electrolyte layer 300 may include sulfide-based solid electrolytes, oxide-based solid electrolytes, etc. Details regarding sulfide-based solid electrolytes and oxide-based solid electrolytes are the same as described above, therefore detailed descriptions will be omitted.

[0208] Meanwhile, the average particle size (D50) of the solid electrolyte included in the solid electrolyte layer 300 can be larger than the average particle size (D50) of the solid electrolyte included in the positive electrode 200. In this case, the overall performance can be improved by maximizing the energy density of the all-solid-state rechargeable battery and increasing the lithium-ion mobility. For example, the average particle size (D50) of the solid electrolyte included in the positive electrode 200 can be 0.1 μm to 1.9 μm or 0.1 μm to 1.0 μm, and the average particle size (D50) of the solid electrolyte included in the solid electrolyte layer 300 can be 2.0 μm to 5.0 μm or 2.0 μm to 4.0 μm or 2.5 μm to 3.5 μm. When the particle size range is met, the energy density of the all-solid-state rechargeable battery is maximized, while promoting lithium-ion transport to suppress resistance, thus improving the overall performance of the all-solid-state rechargeable battery. Here, the average particle size (D50) of the solid electrolyte can be measured by a particle size analyzer using a laser diffraction method.

[0209] In addition to the solid electrolyte, the solid electrolyte layer 300 may further include an adhesive. Here, the adhesive may include, but is not limited to, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate polymers, or combinations thereof. The acrylate polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or combinations thereof.

[0210] The solid electrolyte layer 300 can be formed by adding a solid electrolyte to a binder solution, coating it onto a base film, and drying the result. The solvent in the binder solution can be isobutyl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the solid electrolyte layer is well known in the art, its detailed description will be omitted.

[0211] The thickness of the solid electrolyte layer 300 can be, for example, 10 μm to 150 μm.

[0212] The solid electrolyte layer 300 may further include alkali metal salts and / or ionic liquids and / or conductive polymers.

[0213] The alkali metal salt can be, for example, a lithium salt. The amount of lithium salt in the solid electrolyte layer can be greater than or equal to 1M, for example, 1M to 4M. In this case, the lithium salt can improve the ionic conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0214] Lithium salts can be used without type restriction and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalate)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or combinations thereof.

[0215] For example, lithium salts can be imide lithium salts, such as LiTFSI, LiFSI, LiBETI, or combinations thereof. Imide lithium salts can maintain or improve ionic conductivity by appropriately maintaining their chemical reactivity with ionic liquids.

[0216] Because ionic liquids have melting points below room temperature, they are liquid at room temperature, and refer to salts composed solely of ions or salts composed solely of ions that melt at room temperature.

[0217] Ionic liquids may be compounds including: a) at least one cation selected from ammonium, pyrrolidine, pyridinium, pyrimidine, imidazolium, piperidinium, pyrazolium, oxazoline, pyridazine, phosphorus, thioonium, triazolium, and mixtures thereof; and b) at least one anion selected from BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, Cl-, Br-, I-, BF4-, SO4-, CF3SO3-, (FSO2)2N-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, and (CF3SO2)2N-.

[0218] The ionic liquid may be one or more selected from, for example, N-methyl-N-propylpyrrolomunon bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolomunon bis(3-trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide.

[0219] The weight ratio of solid electrolyte to ionic liquid in the solid electrolyte layer can be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. Solid electrolyte layers meeting these ranges can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrodes. Correspondingly, this can improve the energy density, discharge capacity, and rate performance of all-solid-state rechargeable batteries.

[0220] All-solid-state rechargeable batteries can be single cells with a structure of positive electrode / solid electrolyte layer / negative electrode, dual cells with a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or stacked cells with a structure of repeated single cells.

[0221] Solid-state rechargeable batteries have no particular shape limitations and can be in various forms, such as coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, and flat. Furthermore, solid-state rechargeable batteries can be used in large batteries for electric vehicles. For example, they can also be used in hybrid electric vehicles (such as plug-in hybrid electric vehicles (PHEVs)). Additionally, they can be used in fields requiring large-scale energy storage, such as electric bicycles or power tools. Moreover, solid-state rechargeable batteries can be used in various fields, such as portable electronic devices.

[0222] The following describes embodiments and comparative examples of the present invention. However, it should be understood that the embodiments are for illustrative purposes and should not be construed as limiting the invention.

[0223] Example 1 (0.25 mol%, 460 °C)

[0224] 1. Preparation of positive electrode active material

[0225] Composite oxides were prepared by mixing large and small particles in a weight ratio of 8:2. The large particles exhibited LiNi... 0.945 Co 0.04 Al 0.015 The composition of O2 and its average particle size of approximately 14 μm (D 50 The secondary particles are in the form of LiNi, and the small particles exhibit the characteristics of LiNi. 0.94 Co 0.04 Mn 0.02 The composition of O2 and its average particle size of approximately 3.5 μm (D 50The secondary particles were prepared by mixing 100 mol of the composite oxide, 0.25 mol of zirconium oxide (ZrO2), and 0.5 mol of anhydrous lithium hydroxide (LiOH) using a Henschel mixer for coating. In this study, the mixer was operated at low, medium, and high speeds to ensure uniform coating without layer separation. Subsequently, a heat treatment was performed at 460 °C for 15 hours under an oxygen atmosphere to prepare the final positive electrode active material with the coating formed thereon.

[0226] 2. Manufacturing the positive electrode

[0227] A positive electrode composition was prepared by mixing 84.9 wt% of positive electrode active material, 13.61 wt% of silver-germanium sulfide solid electrolyte Li6PS5Cl, 1 wt% of PVdF binder, 0.35 wt% of carbon nanotube conductive material, and 0.14 wt% of hydrogenated nitrile butadiene rubber (HNBR) as a dispersant in isobutyl isobutyrate (IBIB) solvent. This composition was coated onto a positive electrode current collector, then dried and pressed (using a warm isostatic press (WIP), 500 MPa, 85 °C, 30 min) to obtain the positive electrode.

[0228] 3. Manufacturing all-solid-state rechargeable battery cells

[0229] Carbon black with an initial particle size of approximately 30 nm and an average particle size of approximately 60 nm (D 50 Silver (Ag) was mixed in a 3:1 weight ratio to prepare an Ag / C composite. Then, 0.25 g of the composite was added to 2 g of an NMP solution containing 7 wt% polyvinylidene fluoride binder, and the mixture was stirred to prepare a negative electrode coating composition. This composition was coated onto a negative electrode current collector and dried to prepare a deposition-type negative electrode with a negative electrode coating on the current collector.

[0230] A composition for a solid electrolyte layer was prepared by adding a sulforaphane-germanium ore-type solid electrolyte, Li6PS5Cl, to an IBIB solvent including an acrylic binder. The composition was cast onto a release film and then dried at room temperature to form a solid electrolyte layer.

[0231] After cutting the prepared positive electrode, negative electrode, and solid electrolyte layer, the solid electrolyte layer is stacked on the positive electrode, and the negative electrode is stacked on the solid electrolyte layer. The stacked product is sealed into a bag and then pressed at a high temperature of 80°C (warm isostatic press (WIP)) to 500 MPa for 30 minutes to produce an all-solid-state rechargeable battery cell.

[0232] Example 2 (0.125 mol%, 500) ℃ )

[0233] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that 0.125 moles of zirconium oxide as a coating agent and 0.25 moles of anhydrous lithium hydroxide (LiOH) were mixed in the positive electrode active material manufacturing process, and the coating heat treatment temperature was changed to 500°C.

[0234] Example 3 (0.25 mol%, 500) ℃ )

[0235] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 500°C in the positive electrode active material manufacturing process.

[0236] Example 4 (0.375 mol%, 500) ℃ )

[0237] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that 0.375 moles of zirconium oxide and 0.75 moles of anhydrous lithium hydroxide (LiOH) were mixed in the positive electrode active material manufacturing process, and the coating heat treatment temperature was changed to 500°C.

[0238] Example 5 (0.25 mol%, 540) ℃ )

[0239] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 540°C in the positive electrode active material manufacturing process.

[0240] Comparative Example 1 (0.25 mol%, 300) ℃ )

[0241] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 300°C in the positive electrode active material manufacturing process.

[0242] Comparative Example 2 (0.25 mol%, 400) ℃ )

[0243] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 400°C in the positive electrode active material manufacturing process.

[0244] Comparative Example 3 (0.05 mol%, 500) ℃ )

[0245] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 2, except that 0.05 moles of zirconium oxide and 0.10 moles of anhydrous lithium hydroxide (LiOH) were mixed in the positive electrode active material manufacturing process.

[0246] Comparative Example 4 (0.75 mol%, 500) ℃ )

[0247] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 2, except that 0.75 moles of zirconium oxide and 1.5 moles of anhydrous lithium hydroxide (LiOH) were mixed in the positive electrode active material manufacturing process.

[0248] Comparative Example 5 (0.25 mol%, 600) ℃ )

[0249] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 600°C in the positive electrode active material manufacturing process.

[0250] Comparative Example 6 (0.25 mol%, 700) ℃ )

[0251] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the coating heat treatment temperature was changed to 700°C in the positive electrode active material manufacturing process.

[0252] Comparative Example 7 (Uncoated)

[0253] The positive electrode active material and the all-solid-state rechargeable battery cell were manufactured in essentially the same manner as in Example 1, except that the composite oxide prepared in Example 1 was used as the positive electrode active material itself and no coating was formed on the positive electrode active material.

[0254] Comparative Example 8 (wet coating, 0.25 mol%, 300) ℃ )

[0255] The composite oxide prepared in Example 1 was coated using a wet coating method. The composite oxide was dispersed in a mixture of 2-propanol (after removing moisture), a methanol solution containing 10% lithium methoxide, and zirconium isopropoxide at a molecular ratio (molar ratio) of 200:2:1. To prevent particle aggregation, the solvent was evaporated under vacuum at 50°C while being irradiated with ultrasound. The resulting material was filtered and heat-treated at 300°C for 1 hour in air to obtain a positive electrode active material coated with a buffer layer containing approximately 0.25 wt% Li₂CO₃, LiOH, and ZrO₂.

[0256] All-solid-state rechargeable battery cells were manufactured in essentially the same manner as in Example 1, except that the obtained positive electrode active material was used.

[0257] For ease of understanding, Table 1 below briefly shows the design details of the positive electrode active materials of Examples 1 to 5 and Comparative Examples 1 to 8.

[0258] (Table 1)

[0259]

[0260] Evaluation Example 1: Evaluation of the initial charge / discharge capacity of an all-solid-state rechargeable battery cell

[0261] At 45°C, for initial charging and discharging, the all-solid-state rechargeable battery cells of Examples 1-5 and Comparative Examples 1-8 were charged at a constant current of 0.1C to an upper limit voltage of 4.25V, and then charged at a constant voltage to 0.05C, and then discharged at 0.1C to a cutoff voltage of 2.5V. Table 2 below shows the initial charge capacity, initial discharge capacity, and the ratio of the latter to the former as efficiency. Additionally, Figure 3 The initial charging capacity (gray bar graph) and initial discharging capacity (black bar graph) of Examples 1 to 5 and Comparative Examples 1 to 8 are shown.

[0262] (Table 2)

[0263]

[0264] Refer to Table 2 and Figure 3 Compared to Comparative Example 8, which uses conventional techniques (where an expensive metal alkoxide raw material in an organic solvent is used to form a buffer layer by a wet coating method), Examples 1 to 5 (which apply a mass-producible dry coating method to them) ensure comparable or greater capacity.

[0265] Since the coating heat treatment temperature of Comparative Examples 1 and 2 is lower than that of the Examples, the coatings of Comparative Examples 1 and 2 do not form a suitable crystalline phase but only act as resistors, so Comparative Examples 1 and 2 exhibit low initial charge / discharge capacity.

[0266] Comparative Example 3 uses zirconium oxide as a coating agent in a smaller amount than that of the Examples, in which a thin coating is formed. However, due to the additional addition of lithium hydroxide during the coating process, the residual lithium layer becomes thicker and acts as a buffer layer during initial charging. Comparative Example 3 exhibits a slightly higher charge / discharge capacity than Comparative Example 7, in which no coating was performed.

[0267] Comparative Example 4 uses zirconium oxide as a coating agent in a larger amount than in the Examples, wherein the coating becomes too thick and acts as a resistive layer, and exhibits a reduced initial charge / discharge capacity.

[0268] In Comparative Examples 5 and 6, where the coating heat treatment temperature was higher than that of the examples, it was confirmed that the temperature used to form the crystal phase after coating was too high, causing the coating material to aggregate, which reduced the coating effect or caused the coating material to be absorbed into the positive electrode active material, ultimately reducing the initial charge / discharge capacity.

[0269] Comparative Example 8, which involved wet coating, showed a similar initial discharge capacity to the embodiment but exhibited a lower initial charge capacity. This is understood to be because the coating acts only as a resistive layer and not as a lithium-ion transport layer.

[0270] Evaluation Example 2: Evaluation of the Cycle Life Characteristics of an All-Solid-State Rechargeable Battery Cell

[0271] After the same initial charge and discharge as in Evaluation Example 1, the all-solid-state rechargeable battery cells of Examples 1-5 and Comparative Examples 1-8 were repeatedly charged and discharged 100 times at 0.33C within a voltage range of 2.5V to 4.25V at 45°C. The ratio of the capacity of the 100th discharge to the capacity of the first discharge was calculated, i.e., to evaluate the capacity retention during the cycle life. The results are shown in Table 3. Figure 4 The initial discharge capacity (black bars) and capacity retention after 100 discharges are shown (dashed lines). Additionally, Figure 5 The capacity retention rate based on the number of cycles according to Example 3 and Comparative Examples 3, 4, 6 and 7 is shown.

[0272] (Table 3)

[0273]

[0274] Refer to Table 3 or Figure 4 and Figure 5 Compared with Comparative Example 8, which involved wet coating, Examples 1 to 5, which involved dry coating, ensured superior capacity retention during cycle life.

[0275] The coating heat treatment temperature of Comparative Examples 1 and 2 is lower than that of the embodiment. Comparative Examples 1 and 2 show a capacity retention rate during the cycle life that is comparable to that of the embodiment. However, as mentioned above, the coating does not form a suitable crystalline phase but acts as a resistive layer, resulting in a reduction in the initial discharge capacity.

[0276] Comparative Example 3, which used a lower amount of zirconium oxide as a coating agent than in the examples, exhibited a relatively high initial charge / discharge capacity due to the additional addition of lithium hydroxide during the coating process, resulting in a thicker residual lithium layer that initially acted as a buffer layer. However, as... Figure 5 As shown, the buffer layer decomposes and exhibits insufficient effectiveness during the cycle life, ultimately reducing the capacity retention rate during the cycle life.

[0277] Comparative Example 4, which uses zirconium oxide as a coating agent in a higher amount than in the Examples, demonstrates a high capacity retention rate during cycle life, but exhibits a reduced initial charge / discharge capacity because the coating becomes too thick and acts as a resistive layer.

[0278] Comparative Examples 5 and 6 demonstrate that when the heat treatment temperature is increased to form a crystalline phase after coating, the coating material aggregates together, reducing the coating effect and decreasing the initial discharge capacity and capacity retention during cycle life.

[0279] Evaluation Example 3: Evaluation of Surface Coating Conditions

[0280] SEM images of the positive electrode active materials of Example 3, Comparative Examples 1, and Comparative Examples 3 to 6 were taken, and the images are shown at 50,000x magnification (BSE mode). Figures 6 to 11 In each image, the left image corresponds to large particles, while the right image corresponds to small particles. Figure 6 The images shown are SEM images of the surfaces of the large and small particles in Example 3. Figure 7 SEM images of the surfaces of large and small particles in Comparative Example 1. Figure 8 To compare the SEM images of the surfaces of large and small particles in Example 3, and Figure 9 SEM images of the surfaces of large and small particles in Comparative Example 4. Figure 10 To compare the SEM images of the surfaces of large and small particles in Example 5, and Figure 11 SEM images of the surfaces of large and small particles in Comparative Example 6.

[0281] Compare Figures 6 to 11 Comparative Example 5, which has a coating heat treatment temperature of 600°C. Figure 10 Comparative Example 5 (with a coating heat treatment temperature of 700°C) and Example 6 (with a coating heat treatment temperature of 700°C) Figure 11 No coating was observed on the surface. Additionally, Comparative Example 3, which had the same coating heat treatment temperature of 500°C as Example 3 but used 0.05 molar parts of zirconium oxide for coating, was also used. Figure 8 The coating on the surface was not clearly observed, but Comparative Example 4 (using 0.754 moles of zirconium oxide for coating) was used. Figure 9The coating material is thickly applied and partially aggregated.

[0282] In other words, the coating on the surface should not be too thick or too thin in order to ensure the performance of the all-solid-state rechargeable battery cell.

[0283] Evaluation Example 4: Zr Distribution Analysis Using SEM-EDS

[0284] SEM images of the positive electrode active materials of Example 3, Comparative Examples 1, and Comparative Examples 3-6 were taken to examine the Zr distribution using EDS, and the images show the distribution on the surface. Figures 12-17 In each image, the left image corresponds to large particles, while the right image corresponds to small particles, and Zr is highlighted in yellow. Figure 12 The images shown are SEM-EDS images of large and small particles from Example 3. Figure 13 SEM-EDS images of large and small particles in Comparative Example 1. Figure 14 To compare the SEM-EDS images of large and small particles in Example 3, and Figure 15 SEM-EDS images of large and small particles in Comparative Example 4. Figure 16 To compare the SEM-EDS images of large and small particles in Example 5, and Figure 17 SEM-EDS images of large and small particles in Example 6 are shown for comparison.

[0285] In addition, through EDS analysis Figures 12-17 The Zr content in each region is marked with a square box, and the results are shown in Table 4. In Table 4, the unit is at%.

[0286] (Table 4)

[0287] Zr content Area 1 Area 2 Area 3 Area 4 Area 5 Area 6 Area 7 Example 3 2.9 6.0 2.4 1.6 5.9 - - Comparative Example 1 6.9 1.4 2.8 4.0 8.3 3.2 6.6 Comparative Example 3 0.1 3.8 1.5 0 3.2 0.9 - Comparative Example 4 5.8 10.0 22.0 15.1 6.1 8.8 5.8 Comparative Example 5 8.4 1.8 1.3 6.3 1.6 6.2 2.4 Comparative Example 6 0.6 0.3 2.4 5.5 0.4 1.0 -

[0288] Comparative Example 3, which has the same heat treatment temperature of 500°C as Example 3 but uses 0.05 molar amounts of zirconium oxide (a smaller amount than that in Example 3), is shown in Table 4 and... Figure 14 and Figure 12 It was confirmed that the Zr coating on the displayed surface was uneven and less than that in Example 3. Additionally, as... Figure 15 As shown in Comparative Example 4, which uses an excess of 0.75 moles of zirconium oxide, Zr agglomerates on the surface, and Table 4 also shows significant coating unevenness. In other words, as... Figure 5 As shown in the figure, Comparative Example 3, which lacks sufficient coating, exhibits low cycle life characteristics, and as... Figure 4 As shown, the coating of Comparative Example 4 has too many thick aggregates, and Comparative Example 4 exhibits a low initial discharge capacity.

[0289] Example 1 was compared with Comparative Examples 1 and 5-6 (where zirconia was coated in the same amount of 0.25 molars, but their heat treatment temperatures were varied). Figure 13 Comparative Example 1, which has a lower heat treatment temperature of 300°C, shows that no lithium zirconium oxide (Li6Zr2O7) was formed and therefore no obvious bright signal was detected. In addition, Table 4 shows the large Zr content distribution according to location.

[0290] On the contrary, such as Figure 15 Comparative Example 5, shown in the table, also uses 0.25 molar amounts of zirconium oxide for coating but has a heat treatment temperature of 600°C, which is higher than that of Example 3. It exhibits highly aggregated Zr and, as confirmed by Table 4, a Zr content distribution based on position that is larger than that of Example 3. Additionally, as... Figure 11 Comparative Example 6, shown in the figure, with a heat treatment temperature of 700°C, exhibits a clean surface, and as shown in the figure... Figure 17 The significant amount of Zr detected is shown in Table 4. It should be understood that during heat treatment at 700°C, the coating material was absorbed into the active material or significantly aggregated.

[0291] Evaluation Example 5: Analysis of Coating Crystal Phase using STEM-EDS and HRTEM

[0292] To analyze the crystal phase of the coating, the positive electrode active material of Example 4 was subjected to STEM-EDS analysis on the cross-section of small particles, and the results are shown in... Figure 18 In. Figure 18 In the image, Zr is highlighted with a light green tint. (Reference) Figure 18 Zr is coated very uniformly on the surface of the positive electrode active material. The Zr-containing coating has a thickness of approximately 130 nm.

[0293] Figure 19 This is an HRTEM image of a cross-section of small particles in the positive electrode active material of Example 4. The image was obtained by selecting a thickly coated portion from the surface of the positive electrode active material and marking it with a white square frame. Figure 19 The image is used to determine the region, which is then subjected to an inverse fast Fourier transform (IFFT), and the result is shown in... Figure 20 In. Figure 20 Medium, magnified Figure 20 The ZrO2 region in and shown in Figure 21 On the left side, and magnified the Li6Zr2O7 region and showed it. Figure 21 On the right side. For example... Figure 20 and Figure 21 As shown, the coating is confirmed to have ZrO2 crystalline phase, Li6Zr2O7 crystalline phase and Zr-containing amorphous portion.

[0294] Although the invention has been described in conjunction with exemplary embodiments now regarded as practice, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0295] [Explanation of reference numerals in the attached figures]

[0296] 100: All-solid-state rechargeable battery

[0297] 200: Positive electrode

[0298] 201: Positive electrode current collector

[0299] 203: Positive electrode active material layer

[0300] 300: Solid electrolyte layer

[0301] 400: Negative electrode

[0302] 401: Negative electrode current collector

[0303] 403: Negative electrode active material layer

[0304] 400': Deposition type negative electrode

[0305] 404: Lithium metal layer

[0306] 405: Negative electrode coating

[0307] 500: Elastic layer

Claims

1. A positive electrode active material for a rechargeable lithium battery, comprising: Particles, containing a lithium transition metal composite oxide; And a coating, located on the surface of the particles and containing ZrO2 and Li6Zr2O7.

2. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The coating includes a ZrO2 crystal phase, a Li6Zr2O7 crystal phase, and a Zr-containing amorphous region.

3. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The coating is in the form of a continuous film or islands.

4. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The thickness of the coating is 5 nm to 300 nm.

5. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein Based on 100 mole parts of the particles containing the lithium transition metal composite oxide, the content of Zr in the coating is 0.1 mole part to 0.6 mole part.

6. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein Based on 100 wt% of the positive electrode active material, the content of Zr in the coating is 0.1 wt% to 6 wt%.

7. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The lithium transition metal composite oxide is a lithium nickel-based oxide represented by Chemical Formula 1, a lithium cobalt-based oxide represented by Chemical Formula 2, a lithium iron phosphate-based compound represented by Chemical Formula 3, or a cobalt-free lithium nickel manganese-based oxide represented by Chemical Formula 4: [Chemical Formula 1] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 in, In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each element is independently selected from one or more elements chosen from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, and Zr, and X is selected from one or more elements chosen from the group consisting of F, P, and S. [Chemical Formula 2] Li a2 Co x2 M 3 y2 O 2-b2 X b2 In chemical formula 2, 0.9 ≤ a² ≤ 1.8, 0.7 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.3, 0.9 ≤ x² + y² ≤ 1.1, and 0 ≤ b² ≤ 0.1, M 3 X is selected from one or more elements in the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is selected from one or more elements in the group consisting of F, P, and S. [Chemical Formula 3] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 In chemical formula 3, 0.9 ≤ a³ ≤ 1.8, 0.6 ≤ x³ ≤ 1, 0 ≤ y³ ≤ 0.4, and 0 ≤ b³ ≤ 0.1, M 4 X is selected from one or more elements in the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is selected from one or more elements in the group consisting of F, P, and S. [Chemical Formula 4] Li a4 Ni x4 Mr y4 M 5 z4 O 2-b4 X b4 Among them, in Chemical Formula 4, 0.9 ≤ a4 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1, M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

8. The positive electrode active material for a rechargeable lithium battery according to claim 7, wherein The lithium transition metal composite oxide is the lithium nickel-based oxide represented by Chemical Formula 1, and is a high-nickel oxide satisfying 0.8 ≤ x1 < 1, 0 < y1 ≤ 0.2, and 0 ≤ z1 ≤ 0.

2.

9. The positive electrode active material for a rechargeable lithium battery according to claim 7, wherein The lithium transition metal composite oxide is the lithium nickel-based oxide represented by Chemical Formula 1, and is a high-nickel oxide satisfying 0.9 ≤ x1 < 1, 0 < y1 ≤ 0.1, and 0 ≤ z1 ≤ 0.

1.

10. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The average particle size of the particles containing the lithium transition metal composite oxide is 1 μm to 25 μm.

11. The positive electrode active material for a rechargeable lithium battery according to claim 1, wherein The particles containing the lithium transition metal composite oxide include: Large particles, having an average particle size of 9 μm to 25 μm; And small particles, having an average particle size of 1 μm to 8 μm.

12. The positive electrode active material for a rechargeable lithium battery according to claim 11, wherein Based on 100 wt% of the total of the large particles and the small particles, the positive electrode active material includes 60 wt% to 95 wt% of the large particles and 5 wt% to 40 wt% of the small particles.

13. The positive electrode active material for a rechargeable lithium battery according to claim 11, wherein The large particles are in the form of secondary particles composed of a plurality of primary particles, and the small particles are in the form of secondary particles composed of a plurality of primary particles or in the form of single particles.

14. A method for preparing a positive electrode active material for a rechargeable lithium battery, comprising dry-mixing 100 parts by mole of particles containing a lithium transition metal composite oxide and 0.1 to 0.6 parts by mole of a zirconium raw material, and heat-treating the mixture at 420 °C to 580 °C.

15. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein a lithium raw material is dry-mixed together with the particles containing a lithium transition metal composite oxide and the zirconium raw material.

16. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 15, wherein based on 1 part by mole of the zirconium raw material, the lithium raw material is mixed in an amount greater than 1 part by mole and less than or equal to 4 parts by mole.

17. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein the heat treatment is carried out in an oxygen atmosphere for 5 to 25 hours.

18. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein the zirconium raw material is particles containing zirconia, and the average particle size (D50) of the particles is 10 nm to 500 nm.

19. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein the lithium transition metal composite oxide is a lithium nickel-based oxide represented by Chemical Formula 1, a lithium cobalt-based oxide represented by Chemical Formula 2, a lithium iron phosphate-based compound represented by Chemical Formula 3, or a cobalt-free lithium nickel manganese-based oxide represented by Chemical Formula 4: Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1 in, In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, 0 ≤ z1 ≤ 0.7, 0.9 ≤ x1 + y1 + z1 ≤ 1.1, and 0 ≤ b1 ≤ 0.1, M 1 and M 2 Each element is independently selected from one or more elements chosen from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, Zn, and Zr, and X is selected from one or more elements chosen from the group consisting of F, P, and S. [Chemical Formula 1] Li a2 Co x2 M 3 y2 O 2-b2 X b2 In chemical formula 2, 0.9 ≤ a² ≤ 1.8, 0.7 ≤ x² ≤ 1, 0 ≤ y² ≤ 0.3, 0.9 ≤ x² + y² ≤ 1.1, and 0 ≤ b² ≤ 0.1, M 3 X is selected from one or more elements in the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is selected from one or more elements in the group consisting of F, P, and S. [Chemical Formula 2] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3 In chemical formula 3, 0.9 ≤ a³ ≤ 1.8, 0.6 ≤ x³ ≤ 1, 0 ≤ y³ ≤ 0.4, and 0 ≤ b³ ≤ 0.1, M 4 X is selected from one or more elements in the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn, and Zr, and X is selected from one or more elements in the group consisting of F, P, and S. [Chemical Formula 3] Li a4 Ni x4 Mr y4 M 5 z4 O 2-b4 X b4 Among them, in Chemical Formula 4, 0.9 ≤ a4 ≤ 1.8, 0.8 ≤ x4 < 1, 0 < y4 ≤ 0.2, 0 ≤ z4 ≤ 0.2, 0.9 ≤ x4 + y4 + z4 ≤ 1.1, and 0 ≤ b4 ≤ 0.1, M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S. [Chemical Formula 4] [[ID=z18]]20. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein the lithium transition metal composite oxide is the lithium nickel-based oxide represented by Chemical Formula 1, and is a high-nickel-based oxide satisfying 0.8 ≤ x1 < 1, 0 < y1 ≤ 0.2, and 0 ≤ z1 ≤ 0.

2. The particles containing lithium transition metal composite oxides include:

21. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 14, wherein the large particles have an average particle size of 9 μm to 25 μm; and the small particles have an average particle size of 1 μm to 8 μm.

22. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 21, wherein based on the total of 100 wt% of the large particles and the small particles, the large particles are included in an amount of 60 wt% to 95 wt% and the small particles are included in an amount of 5 wt% to 40 wt%.

23. The method for preparing a positive electrode active material for a rechargeable lithium battery according to claim 21, wherein the large particles are in the form of secondary particles composed of a plurality of primary particles, and The small particles may be in the form of secondary particles composed of multiple primary particles or in the form of a single particle.

24. A positive electrode for a rechargeable lithium battery, comprising a positive electrode active material according to any one of claims 1 to 13.

25. The positive electrode for a rechargeable lithium battery according to claim 24, wherein... The positive electrode further comprises a sulfide-based solid electrolyte.

26. The positive electrode for a rechargeable lithium battery according to claim 25, wherein... The positive electrode comprises, based on a total of 100 wt% of the positive electrode active material and the sulfide-based solid electrolyte, 65 wt% to 99 wt% of the positive electrode active material and 1 wt% to 35 wt% of the sulfide-based solid electrolyte.

27. The positive electrode for a rechargeable lithium battery according to claim 25, wherein... The sulfide-based solid electrolyte includes sulfide of the silver-germanium sulfide type, and the sulfide-based solid electrolyte is in the form of particles, and the average particle size (D50) of the particles is 0.1 μm to 3.0 μm.

28. A rechargeable lithium battery, comprising: The positive electrode according to claim 24, negative electrode, and Electrolytes.

29. An all-solid-state rechargeable battery, comprising: The positive electrode according to claim 24, negative electrode, and A solid electrolyte layer between the positive electrode and the negative electrode.

30. The all-solid-state rechargeable battery according to claim 29, wherein The negative electrode includes: current collector; A negative electrode coating, disposed on the current collector and containing a lithium-philic metal, a carbon material, or a combination thereof, and A lithium metal layer is formed between the current collector and the negative electrode coating by charging.

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