Positive active material for all-solid-state battery, method for preparing the same, and all-solid-state battery

Abstract

Disclosed are a positive electrode active material of an all-solid-state battery, a method of preparing the same, and an all-solid-state battery. The positive electrode active material includes secondary particles in which a plurality of primary particles are aggregated, wherein at least a portion of the primary particles are radially arranged, and includes a first boron coating portion on a surface of the secondary particles, and a second boron coating portion on a surface of the primary particles in an inner portion of the secondary particles.

Description

Technical Field

[0001] The positive electrode active material for all-solid-state batteries, the method for preparing the material, and the all-solid-state battery are disclosed. Background Technology

[0002] Portable information devices, such as cell phones, laptops, and smartphones, as well as 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 or electric vehicles.

[0003] All-solid-state batteries, a type of rechargeable lithium-ion battery, refer to batteries in which all materials are solid, and especially those using solid electrolytes. These all-solid-state batteries are safe, have no risk of explosion due to electrolyte leakage, and are easy to manufacture into thin batteries.

[0004] Recently, various positive electrode active materials applicable to all-solid-state batteries have been studied. The main research focuses on conventionally used lithium nickel oxide, lithium nickel manganese cobalt composite oxide, lithium nickel cobalt aluminum composite oxide, and lithium cobalt oxide, but these have limitations in achieving satisfactory performance in all-solid-state batteries. Accordingly, new positive electrode active materials need to be developed to ensure long cycle life and achieve high-capacity and high-energy-density all-solid-state batteries. Summary of the Invention

[0005] A positive electrode active material for all-solid-state batteries, a method for preparing the material, and an all-solid-state battery including the material are provided, which achieve high capacity while improving cycle life.

[0006] In one embodiment, the positive electrode active material for an all-solid-state battery includes a lithium-nickel composite oxide, wherein the positive electrode active material includes: secondary particles in which a plurality of primary particles are aggregated, wherein at least a portion of the primary particles are radially arranged; a first boron coating portion on the surface of the secondary particles; and a second boron coating portion on the surface of the primary particles in the inner portion of the secondary particles.

[0007] Each of the first boron coating portion and the second boron coating portion may include boron oxide, lithium boron oxide, or a combination thereof.

[0008] The weight of the first boron coating portion can be greater than the weight of the second boron coating portion.

[0009] Based on the total amount of the first boron coating portion and the second boron coating portion, the first boron coating portion may be included in an amount of about 70 wt% to about 98 wt%, and the second boron coating portion may be included in an amount of about 2 wt% to about 30 wt%.

[0010] Based on the total weight of the positive electrode active material, the content of the first boron coating portion can be from about 0.02 wt% to about 0.3 wt%.

[0011] Based on the total weight of the positive electrode active material, the content of the second boron coating portion can be from about 0.001 wt% to about 0.05 wt%.

[0012] Based on 100 mol% of the positive electrode active material, the total amount of the first boron coating portion and the second boron coating portion can be from about 0.1 mol% to about 3 mol% or from about 0.1 mol% to about 1.5 mol%.

[0013] The primary particles may be plate-shaped, and at least a portion of the plate-shaped primary particles may have long axes arranged in the radial direction.

[0014] The plate-shaped primary particles have an average length of about 150 nm to about 500 nm, an average thickness of about 100 nm to about 200 nm, and a ratio of average thickness to average length of about 1:2 to about 1:5.

[0015] Secondary particles may include an internal portion comprising an irregular porous structure and an external portion comprising a radially arranged structure.

[0016] The internal portion of the secondary particle may have a larger pore size than the external portion, with the pore size in the internal portion of the secondary particle being from about 150 nm to about 1 μm, and the pore size in the external portion of the secondary particle being less than about 150 nm.

[0017] Secondary particles may include openings with a size of less than about 150 nm on the surface facing the center of the inner portion.

[0018] Lithium-nickel composite oxides can be represented by chemical formula 1.

[0019] [Chemical Formula 1]

[0020] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0021] In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, M 1 and M 2 Each is independently selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr and combinations thereof.

[0022] In another embodiment, a method for preparing a positive electrode active material for all-solid-state batteries includes mixing a lithium feedstock, a nickel hydroxide, and a boron feedstock, and then heat-treating the resulting product.

[0023] Based on 100 mol% nickel hydroxide, the boron raw material content can be from about 0.1 mol% to about 3 mol%.

[0024] It can be heat-treated at a temperature of about 650°C to about 850°C for about 5 hours to about 20 hours.

[0025] Another embodiment provides an all-solid-state battery, comprising: a positive electrode including a positive electrode active material, a negative electrode, and a solid electrolyte between the positive electrode and the negative electrode.

[0026] The positive electrode active material for all-solid-state batteries according to the embodiments and the all-solid-state batteries including the thereof can exhibit excellent cycle life characteristics while achieving high capacity and high energy density. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the plate-like shape of the primary particles according to an embodiment.

[0028] Figure 2 This is a view used to explain the radial definition in secondary particles according to an embodiment.

[0029] Figure 3 This is a schematic diagram showing the cross-sectional structure of the secondary particles according to an embodiment.

[0030] Figure 4A A cross-sectional view of an all-solid-state battery according to an embodiment is shown for illustrative purposes.

[0031] Figure 4B A cross-sectional view of an all-solid-state battery according to an embodiment is shown for illustrative purposes.

[0032] Figure 5 Scanning electron microscope image of the fractured surface of the precursor of the positive electrode active material in Example 1.

[0033] Figure 6 This is a scanning electron microscope image of the cross-section of the positive electrode active material of Example 1.

[0034] Figure 7 This is a scanning electron microscope image of the cross-section of the positive electrode active material in Example 2.

[0035] Figure 8 A scanning electron microscope image of the cross-section of the positive electrode active material of Comparative Example 2.

[0036] Figure 9This is a time-of-flight secondary ion mass spectrometry (ToF-SIMS) image of the positive electrode active material in Example 1.

[0037] Figure 10 The mass spectrometry results of the ToF-SIMS analysis of the positive electrode active material in Example 1 are shown.

[0038] Figure 11 The X-ray spectra (XPS) results are for the positive electrode active materials of Examples 1 and 2, and for the positive electrode active material of Example 1 after washing.

[0039] Figure 12 The cycle life evaluation results are for the all-solid-state battery cells of the examples and comparative examples.

[0040] <Description of reference numerals in the attached figures>

[0041] 11: Secondary particles

[0042] 12: The internal part of secondary particles

[0043] 13: Primary particles

[0044] 14: The outer part of secondary particles

[0045] 100: All-solid-state battery; 200: Positive electrode

[0046] 201: Positive electrode; 203: Positive electrode active material layer

[0047] 300: Solid electrolyte layer; 400: Negative electrode

[0048] 401: Negative current collector; 403: Negative electrode active material layer

[0049] 400': Precipitation-type negative electrode

[0050] 404: Lithium metal layer

[0051] 405: Negative electrode catalyst layer

[0052] 500: Elastic layer Detailed Implementation

[0053] 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.

[0054] 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.

[0055] As used in this article, “combination of” means mixtures of components, laminates, complexes, copolymers, alloys, blends, and reaction products, etc.

[0056] 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.

[0057] In the accompanying drawings, for clarity, the thicknesses of layers, films, panels, regions, etc., are enlarged, and throughout the specification, the same reference numerals denote the same elements. It should be understood that when an element, such as a layer, film, region, 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.

[0058] In addition, the term "layer" in this article includes not only shapes that form on the entire surface when viewed from a plan view, but also shapes that form on a portion of the surface.

[0059] Additionally, the average particle size can be measured using methods well known to those skilled in the art, for example, by a particle size analyzer, or by transmission electron microscopy or scanning electron microscopy. Alternatively, the average particle diameter value may be obtained by measuring using dynamic light scattering methods, performing data analysis, counting the number of particles in each particle size range, and thereby calculating. Unless otherwise defined, the average particle size may mean the diameter (D50) of particles that constitute 50% of the total volume in the particle size distribution.

[0060] Positive electrode active material

[0061] The embodiments provide a positive electrode active material for all-solid-state batteries, comprising a lithium-nickel composite oxide, wherein the positive electrode active material includes: secondary particles in which a plurality of primary particles are aggregated, wherein at least a portion of the primary particles are radially arranged; a first boron coating portion on the surface of the secondary particles; and a second boron coating portion on the surface of the primary particles in the internal portion of the secondary particles.

[0062] All-solid-state batteries suffer from inadequate capacity performance due to high resistance at the interface between the positive electrode active material and the solid electrolyte. This is caused by the formation of an impurity layer through chemical reactions between the positive electrode active material and the solid electrolyte, or by the formation of a space charge layer due to the contact between the positive electrode active material and the solid electrolyte. To address this issue, techniques have been developed to form a buffer layer with lithium-ion conductivity at the interface between the positive electrode active material and the solid electrolyte. However, forming this buffer layer requires methods such as sol-gel processes using organic solvents, spray drying, or atomic layer deposition, which result in excessive processing costs and thus limit practical applications for large-scale production.

[0063] According to the embodiment, the positive electrode active material is coated with boron compounds or the like on the surface of the secondary particles and at the internal grain boundaries. This eliminates the need for a separate buffer layer formation process, suppressing the interfacial resistance between the positive electrode active material and the solid electrolyte, thereby achieving high capacity. Furthermore, because the boron compounds or the like are coated at the internal grain boundaries and on the surface of the secondary particles, the positive electrode active material retains the buffer layer despite volume changes during charging and discharging, thus achieving long cycle life characteristics.

[0064] The positive electrode active material includes a first boron coating portion on the surface of the secondary particles and a second boron coating portion on the surface of the primary particles within the internal portion of the secondary particles. Both the first and second boron coating portions comprise boron compounds. The boron compounds may include, for example, boron oxides, lithium boron oxides, or combinations thereof, such as B2O2, B2O3, B4O3, B4O5, LiBO2, Li2B4O7, Li3BO3, or combinations thereof.

[0065] The second boron coating is partially present within the interior portion of the secondary particles rather than on the surface, and it is coated along the interface of the primary particles within the interior portion of the secondary particles, and therefore can be represented as being coated at the grain boundaries. Here, the interior portion of the secondary particles means the entire interior outside the surface, for example, it can mean the entire interior from a depth of approximately 2 μm from the outer surface. When the secondary particles of the positive electrode active material are washed with distilled water, it can also be represented as the portion that distilled water cannot reach.

[0066] Conventional methods for coating boron onto cathode active materials typically involve mixing boron feedstock with lithium metal composite oxide using a wet or dry process, followed by heat treatment. However, boron has the problem of acting as a resistive agent on the surface of the cathode active material, thus significantly degrading capacity and cycle life. Conversely, according to an embodiment, a method can be employed whereby boron feedstock is injected together with lithium feedstock into a precursor in which primary particles are radially oriented, and then they can be heat-treated to provide a cathode active material coated with boron at the internal grain boundaries and on its surface. Because an appropriate amount of boron is coated at the internal grain boundaries and simultaneously on the surface of the cathode active material, boron no longer acts as a resistive agent, but instead ensures the structural stability of the cathode active material and suppresses the interfacial resistance between the cathode active material and the solid electrolyte, thereby improving the battery's capacity characteristics and long-term cycle life.

[0067] According to an embodiment, the weight of the first boron coating portion may be greater than the weight of the second boron coating portion. For example, based on the total amount of the first and second boron coating portions, the second boron coating portion may be included in an amount of about 2 wt% to about 30 wt%, specifically about 3 wt% to about 25 wt%, or about 5 wt% to about 20 wt%, and the first boron coating portion may be included in an amount of about 70 wt% to about 98 wt%, about 75 wt% to about 97 wt%, or about 80 wt% to about 95 wt%. For example, the weight ratio of the first and second boron coating portions may be about 70:30 to about 98:2, for example, about 70:30 to about 97:3 or about 75:25 to about 95:5. When the amount and weight ratio of the first and second boron coating portions are as described above, boron does not act as a resistor in the positive electrode active material and can be used to improve performance. Furthermore, the positive electrode active material including such a boron coating portion can exhibit improved cycle life characteristics while achieving high capacity.

[0068] The content of the first boron coating portion, based on the total weight of the positive electrode active material, can be, for example, about 0.02 wt% to about 0.3 wt%, about 0.03 wt% to about 0.3 wt%, about 0.04 wt% to about 0.2 wt%, or about 0.05 wt% to about 0.1 wt%. The content of the second boron coating portion, based on the total weight of the positive electrode active material, can be, for example, about 0.001 wt% to about 0.05 wt%, about 0.001 wt% to about 0.04 wt%, about 0.002 wt% to about 0.03 wt%, or about 0.003 wt% to about 0.02 wt%, but is not limited thereto. When the contents of the first and second boron coating portions, based on the total weight of the positive electrode active material, are as described above, boron does not act as a resistor in the positive electrode active material, and the positive electrode active material including it can exhibit high capacity and excellent cycle life characteristics.

[0069] Based on 100 mol% of the positive electrode active material, the total amount of the first boron coating portion and the second boron coating portion can be from about 0.1 mol% to about 3 mol%, for example, from about 0.1 mol% to about 2.5 mol%, from about 0.1 mol% to about 2 mol%, from about 0.1 mol% to about 1.5 mol%, from about 0.1 mol% to about 1.3 mol%, or from about 0.5 mol% to about 1.3 mol%. When the total amount of the first boron coating portion and the second boron coating portion exceeds a predetermined content, the initial discharge capacity can be reduced and the cycle life characteristics can be degraded. In particular, if the content of the first boron coating portion on the surface of the secondary particles is too high, the initial discharge capacity of the all-solid-state battery can be greatly reduced due to the resistive effect of boron.

[0070] On the other hand, the positive electrode active material includes secondary particles in which at least two primary particles are aggregated, and at least a portion of the primary particles have a radially aligned structure. At least some of the primary particles may be plate-like. The primary particles may have a thickness less than the length of their major axis. Here, the length of the major axis means the maximum length with respect to the widest surface of the primary particle. That is, the primary particles may have a structure in which the length (t) in one axial direction (i.e., the thickness direction) is less than the length (a) of the major axis in another direction (i.e., the planar direction).

[0071] Figure 1 This is a schematic diagram showing the plate-like structure of the primary particles of the positive electrode active material. (Reference) Figure 1 The primary particles according to the embodiments have various detailed shapes, while having a basic plate structure, such as (A) polygonal nanoplate shapes, like hexagons, (B) nanodisc shapes, and (C) cuboid shapes. Figure 1 In this context, "a" represents the length of the major axis of the primary particle, "b" represents the length of the minor axis, and "t" represents the thickness. The thickness t of the primary particle can be less than the lengths a and b in the planar direction. Among the lengths in the planar direction, a can be longer than or equal to b. The direction defining the thickness t in the primary particle is defined as the thickness direction, and the direction having lengths a and b is defined as the planar direction.

[0072] In the positive electrode active material, at least a portion of the primary particles may have a radially arranged structure, and for example, the long axis of the primary particles may be aligned in the radial direction. Figure 2 This is a view used to explain the radial definition in secondary particles according to an embodiment. In the embodiment, radial arrangement means, as... Figure 2 The data shows that the thickness (t) of the primary particle is perpendicular to the direction (R) from the center of the secondary particle toward the surface, or within an angle of approximately ±5° from the direction (R) from the center of the secondary particle toward the surface.

[0073] At least a portion of the primary particles may be radially oriented. That is, all or some of the primary particles in the secondary particles may be radially oriented. For example, a secondary particle may include an outer portion and an inner portion, and the primary particles in both the outer and inner portions may be radially oriented, or only the primary particles in the outer portion may be radially oriented. As another example, a secondary particle may include an outer portion in which the primary particles are radially oriented and an inner portion in which the primary particles are irregularly arranged.

[0074] The average length of the primary particles in the secondary particles can be from about 0.01 μm to about 5 μm, for example, from about 0.01 μm to about 2 μm, from about 0.01 μm to about 1 μm, from about 0.02 μm to about 1 μm, from about 0.05 μm to about 0.5 μm, or from about 150 nm to about 500 nm. Here, "average length" means the average length of the major axis (a) in the planar direction when the primary particles are plate-shaped, and when the primary particles are spherical, it means the average particle size.

[0075] When the primary particles are plate-shaped, the average thickness of the primary particles may be, for example, greater than or equal to about 50 nm, greater than or equal to about 100 nm, greater than or equal to about 200 nm, greater than or equal to about 300 nm, greater than or equal to about 400 nm, greater than or equal to about 500 nm, greater than or equal to about 600 nm, greater than or equal to about 700 nm, greater than or equal to about 800 nm, or greater than or equal to about 900 nm, and for example, less than or equal to about 5 μm, less than or equal to about 4 μm, less than or equal to about 3 μm, less than or equal to about 2 μm, less than or equal to about 1 μm, less than or equal to about 900 nm, less than or equal to about 800 nm, less than or equal to about 700 nm, less than or equal to about 600 nm, or less than or equal to about 500 nm, for example, from about 100 nm to about 200 nm. In addition, in the primary particles, the ratio of average thickness to average length can be from about 1:1 to about 1:10, for example, from about 1:1 to about 1:8, from about 1:1 to about 1:6, or from about 1:2 to about 1:5.

[0076] As mentioned above, when the average length, average thickness, and ratio between the average thickness and average length of the primary particles meet the aforementioned ranges, and the primary particles are radially aligned, there may be relatively more lithium diffusion paths between the grain boundaries on the surface side, and a large number of crystal faces capable of lithium transfer are exposed on the outside, thereby improving lithium diffusion and ensuring high initial efficiency and capacity. Furthermore, when the primary particles are radially aligned, the pores exposed on the surface are guided toward the center of the secondary particles, thereby promoting lithium diffusion. Due to the radially aligned primary particles, uniform contraction and expansion are possible during lithium deintercalation and / or intercalation, and when lithium deintercalation occurs, the pores exist in the (001) direction, which is the direction of particle expansion, so that they act as a buffer. Additionally, due to the size and arrangement of the primary particles, the probability of cracking during the contraction and expansion of the active material is reduced, and the internal pores further mitigate volume changes to reduce cracks generated between primary particles during charging and discharging, resulting in improved cycle life characteristics and reduced resistance increase in all-solid-state batteries.

[0077] The positive electrode active material may have an irregular porous structure in at least one of the internal and external portions of the secondary particles. The term "irregular porous structure" refers to a structure in which the pore size and shape are irregular and non-uniform. For example, the secondary particles may include: an internal portion comprising an irregular porous structure and an external portion comprising a radially arranged structure. That is, unlike the primary particles in the external portion, the primary particles in the internal portion may be irregularly arranged. Like the external portion, the internal portion containing the irregular porous structure includes primary particles.

[0078] The term "external portion" can refer (e.g., of a particle) to the region within approximately 30% to 50% of the length from the outermost surface, in terms of distance from the center of the secondary particle to the surface, for example, the region within approximately 40% of the length from the outermost surface, or in some embodiments, the region within approximately 2 μm of the outermost surface of the secondary particle. The term "internal portion" can refer (e.g., of a particle) to the region within approximately 50% to 70% of the length from the center of the secondary particle to the surface, for example, the region within approximately 60% of the length from the center, or in some embodiments, the region outside the region within approximately 2 μm of the outermost surface of the secondary particle.

[0079] The secondary particles of the positive electrode active material comprise a radially oriented external structure and an irregular porous internal structure, wherein the interior of the secondary particles may have larger pores than the exterior. For example, the positive electrode active material may have an internal pore size of about 150 nm to about 1 μm and an external pore size of less than about 150 nm. Thus, when the internal pore size is larger than the external pore size, compared to secondary particles with the same internal and external pore sizes, there is an advantage in shortening the diffusion distance of lithium in the active material, and lithium can be easily inserted from the outside. Additionally, it can have the effect of mitigating volume changes during charging and discharging. In this context, pore size refers to the average diameter when the pore is spherical or circular, and the length of the major axis when the pore is elliptical.

[0080] The secondary particles of the positive electrode active material may have openings with a size less than about 150 nm, for example, from about 10 nm to about 148 nm, on the surface facing the center of the inner portion. The openings may be exposed pores through which electrolyte can flow in and out. The openings may be formed at a depth of less than or equal to about 150 nm from the surface of the secondary particles, for example, from about 0.001 nm to about 100 nm, or for example, from about 1 nm to about 50 nm.

[0081] Closed pores may exist in the internal portion of the secondary particle, and closed pores and / or open pores may exist in the external portion. Closed pores may contain little or no electrolyte, while open pores may contain electrolyte. Closed pores are independent pores that are not connected to other pores because all walls of the pore are formed in a closed structure, while open pores are continuous pores that are connected to the outside of the particle because at least some walls of the pore are formed in an open structure.

[0082] Figure 3 A schematic diagram illustrating the cross-sectional structure of the secondary particles in the positive electrode active material. (Reference) Figure 3 According to the embodiment, the secondary particles 11 of the positive electrode active material have an outer portion 14, wherein plate-shaped primary particles 13 are arranged radially therein; and an inner portion 12, in which the primary particles 13 are irregularly arranged. Compared to the outer portion 14, the inner portion 12 may have more blank space between the primary particles 13. Furthermore, compared to the pore size and porosity in the outer portion 14, the pore size and porosity in the inner portion 12 are larger and more irregular. Figure 3 In the image, the arrows indicate the direction of lithium ion movement.

[0083] In the secondary particles, the internal portion has a porous structure, which reduces the diffusion distance of lithium ions to the internal portion, while the external portion is radially aligned towards the surface, facilitating lithium ion embedding into the surface. Furthermore, the small size of the primary particles ensures efficient lithium transfer paths between grains. Additionally, the small size of the primary particles and the porosity between them mitigate volume changes during charging and discharging, thus minimizing stress caused by these volume changes. This positive electrode active material reduces the resistance of all-solid-state batteries and improves capacity and cycle life characteristics.

[0084] On the other hand, in the secondary particles, multiple primary particles can have a radial alignment structure by aligning towards a "single" center, so that the surface contacts along the thickness direction of the primary particles. Optionally, the secondary particles can have a "multi-center" radial alignment structure with multiple centers. Therefore, when the secondary particles have a single-center or multi-center radial alignment structure, lithium is readily de-intercalated and / or intercalated into the center of the secondary particles.

[0085] Secondary particles may include radial primary particles and non-radial primary particles. Based on the total weight of 100 parts by weight of radial and non-radial primary particles, the content of non-radial primary particles may be less than or equal to about 20 wt%, for example, from about 0.01 wt% to about 10 wt%, specifically from about 0.1 wt% to about 5 wt%. When non-radial primary particles are included in the above-mentioned content range in addition to radial primary particles in the secondary particles, an all-solid-state battery with improved cycle life characteristics can be provided by promoting lithium diffusion.

[0086] The positive electrode active material includes nickel-containing composite oxides, and may also include lithium-nickel composite oxides. Based on the total amount of metals other than lithium, the nickel content in lithium-nickel composite oxides can be greater than or equal to about 30 mol%, for example, greater than or equal to about 40 mol%, greater than or equal to about 50 mol%, greater than or equal to about 60 mol%, greater than or equal to about 70 mol%, greater than or equal to about 80 mol%, or greater than or equal to about 90 mol% and less than or equal to about 99.9 mol%, or less than or equal to about 99 mol%. For example, the nickel content in lithium-nickel composite oxides can be higher than the content of each of other metals, such as cobalt, manganese, and aluminum. When the nickel content meets the above ranges, the positive electrode active material can exhibit excellent battery performance while achieving high capacity.

[0087] Lithium-nickel composite oxides can be represented by chemical formula 1.

[0088] [Chemical Formula 1]

[0089] Li a1 Ni x1 M 1y1 M 2 1-x1-y1 O2

[0090] In Chemical Formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, and M 1 and M 2 are each independently selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr, and combinations thereof.

[0091] In Chemical Formula 1, 0.4 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.6, 0.5 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.5, 0.6 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.4, or 0.7 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.3, 0.8 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.2, or 0.9 ≤ x1 ≤ 1 and 0 ≤ y1 ≤ 0.1.

[0092] The lithium nickel-based composite oxide can be represented, for example, by Chemical Formula 2.

[0093] [Chemical Formula 2]

[0094] Li a2 Ni x2 Co y2 M 3 1-x2-y2 O2

[0095] In Chemical Formula 2, 0.9 ≤ a2 ≤ 1.8, 0.3 ≤ x2 < 1, 0 < y2 ≤ 0.7, and M 3 is selected from Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr, and combinations thereof.

[0096] In Chemical Formula 2, 0.3 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.7, 0.4 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.6, 0.5 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.5, or 0.6 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.4, 0.7 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.3, 0.8 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.2, or 0.9 ≤ x2 ≤ 0.99 and 0.01 ≤ y2 ≤ 0.1.

[0097] The lithium nickel-based composite oxide can be represented, for example, by Chemical Formula 3.

[0098] [Chemical Formula 3]

[0099] Li a3Ni x3 Co y3 M 4 z3 M 5 1-x3-y3-z3 O2

[0100] In chemical formula 3, 0.9 ≤ a³ ≤ 1.8, 0.3 ≤ x³ ≤ 0.98, 0.01 ≤ y³ ≤ 0.69, 0.01 ≤ z³ ≤ 0.69, M 4 Selected from Al, Mn and their combinations, and M 5 Selected from B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr and combinations thereof.

[0101] In chemical formula 3, 0.4≤x3≤0.98, 0.01≤y3≤0.59 and 0.01≤z3≤0.59, for example, 0.5≤x3≤0.98, 0.01≤y3≤0.49 and 0.01≤z3≤0.49, or 0.6≤x3≤0.98, 0.01≤y3≤0.39 and 0.01≤z3≤0.39, or 0.7≤x3≤0.98, 0.01≤y3≤0.29 and 0.01≤z3≤0.29, or 0.8≤x3≤0.98, 0.01≤y3≤0.19 and 0.01≤z3≤0.19, or 0.9≤x3≤0.98, 0.01≤y3≤0.09 and 0.01≤z3≤0.09.

[0102] Typically, as the nickel content in the positive electrode active material increases, due to the increase in Ni content... 2+ The increased mixing of cations occupying lithium sites also significantly reduces capacity. Furthermore, impurities such as NiO hinder lithium-ion diffusion, leading to degraded battery cycle life. Additionally, the positive electrode active material undergoes side reactions with the electrolyte due to structural collapse and cracking during charging and discharging, further reducing cycle life and causing safety issues. To address these problems, in conventional methods where boron is only coated on the surface of the active material, boron acts as a resistor, significantly reducing capacity and degrading cycle life. Conversely, the positive electrode active material according to the embodiment, even when using high-nickel materials, has an appropriate amount of boron coated on the surface and at the internal grain boundaries. Correspondingly, it improves upon the problems caused by high-concentration nickel plating, thus achieving high capacity and simultaneously improving cycle life characteristics without degrading the initial discharge capacity.

[0103] Methods for preparing positive electrode active materials

[0104] In one embodiment, the method for preparing the positive electrode active material for all-solid-state batteries includes mixing lithium raw materials, nickel hydroxides and boron raw materials, and heat-treating the resulting product.

[0105] Conventionally, when boron is coated onto the positive electrode active material, lithium feedstock is typically mixed with a nickel transition metal complex hydroxide, followed by heat treatment of the result to prepare a lithium-nickel composite oxide. Boron feedstock is then mixed with it using a wet or dry process, followed by another heat treatment. In this case, boron is only coated on the surface of the positive electrode active material, and therefore acts as a resistor, reducing capacity and cycle life. On the other hand, according to the preparation method described in the embodiment, a positive electrode active material coated with boron not only on the surface of the positive electrode active material but also at the grain boundaries within the internal portion of the positive electrode active material can be obtained.

[0106] According to this method, the boron coating portion of the positive electrode active material can be used as a buffer layer in an all-solid-state battery to suppress the interfacial resistance between the positive electrode active material and the solid electrolyte, thereby improving the capacity characteristics of the all-solid-state battery. Furthermore, because boron is also coated at the internal grain boundaries of the positive electrode active material, compared to conventional active materials with coatings or buffer layers only on the surface, the performance of the buffer layer can be maintained despite volume changes in the positive electrode active material during charging and discharging, thus improving the long-term cycle life characteristics of the all-solid-state battery.

[0107] In the above manufacturing method, the nickel hydroxide can be a nickel transition metal complex hydroxide that serves as a precursor for the positive electrode active material, and it is prepared using a co-precipitation method or the like. The nickel hydroxide can have a structure in which at least a portion of the primary particles are radially oriented. This radially oriented structure is the same as described above.

[0108] Nickel hydroxides can be, for example, represented by chemical formula 11.

[0109] [Chemical Formula 11]

[0110] Ni x11 M 11 y11 M 12 1-x11-y11 (OH)2

[0111] In chemical formula 11, 0.3 ≤ x11 ≤ 1, 0 ≤ y11 ≤ 0.7, and M 11 and M 12 It is independently selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr and combinations thereof.

[0112] As a specific example, nickel hydroxides can be represented by chemical formula 12 or chemical formula 13.

[0113] [Chemical Formula 12]

[0114] Ni x12 Co y12 M 13 1-x12-y12 (OH)2

[0115] In Chemical Formula 12, 0.3 ≤ x12 < 1, 0 < y12 ≤ 0.7, and M 13 is selected from Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr, and combinations thereof.

[0116] [Chemical Formula 13]

[0117] Ni x13 Co y13 M 14 z13 M 15 1-x13-y13-z13 (OH)2

[0118] In Chemical Formula 13, 0.3 ≤ x13 ≤ 0.98, 0.01 ≤ y13 ≤ 0.69, 0.01 ≤ z13 ≤ 0.69, M 14 is selected from Al, Mn, and combinations thereof, and M 15 is selected from B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr, and combinations thereof.

[0119] The lithium raw material can be, for example, lithium hydroxide, etc., and can be mixed in a ratio of about 0.8 moles to about 1.8 moles, about 0.9 moles to about 1.8 moles, or about 0.8 moles to about 1.2 moles based on the total amount of metals in 1 mole of nickel-based hydroxide.

[0120] The boron raw material can be a boron-containing compound, for example, H3BO3, HBO2, B2O3, C6H5B(OH)2, (C6H5O)3B, [CH3(CH2)3O]3B, (C3H7O)3B, C3H9B3O6, C 13 H 19 BO3, or combinations thereof.

[0121] Based on 100 mol% nickel hydroxide, the boron content can be from about 0.1 mol% to about 3 mol%, for example, from about 0.1 mol% to about 2.9 mol%, from about 0.1 mol% to about 2.5 mol%, from about 0.1 mol% to about 2 mol%, from about 0.1 mol% to about 1.5 mol%, or from about 0.5 mol% to about 1.3 mol%. When the boron content meets the above ranges, boron does not act as a resistor in the positive electrode active material and can be used to improve the performance of all-solid-state batteries, thereby increasing capacity and cycle life characteristics. When the boron content is too high, the content of the first boron coating portion increases excessively, and boron acts as a resistor in the positive electrode active material, thereby reducing the battery capacity and cycle life.

[0122] The heat treatment can be performed at a temperature of about 650°C to about 850°C, or about 690°C to about 780°C. Under these conditions, a positive electrode active material for all-solid-state batteries can be prepared, which has a stable structure comprising both a first boron coating portion and a second boron coating portion.

[0123] Additionally, the heat treatment can be carried out for approximately 5 hours to approximately 25 hours, for example, 5 hours to 20 hours or approximately 8 hours to approximately 12 hours. In this case, a positive electrode active material for all-solid-state batteries is prepared, which has a stable structure comprising both a first boron coating portion and a second boron coating portion.

[0124] All-solid-state batteries

[0125] In an embodiment, the all-solid-state battery includes: a positive electrode comprising the aforementioned positive electrode active material, a negative electrode, and a solid electrolyte layer between the positive electrode and the negative electrode. An all-solid-state battery can also be referred to as an all-solid-state rechargeable battery.

[0126] Figure 4A A cross-sectional view illustrating an all-solid-state battery according to an embodiment. (Reference) Figure 4A The all-solid-state battery 100 may have a structure in which an electrode assembly is inserted into a housing, such as a pouch, and in which a negative electrode 400, including a negative current collector 401 and a negative electrode active material layer 403, a solid electrolyte layer 300, and a positive electrode 200 including a positive electrode active material layer 203 and a positive current collector 201 are stacked. The all-solid-state battery 100 may further include at least one elastic layer 500 on the outside of at least one of the positive electrode 200 and the negative electrode 400. Figure 4A 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 create an all-solid-state battery.

[0127] positive electrode

[0128] The positive electrode for an all-solid-state battery may include a current collector and a layer of positive electrode active material on the current collector. The positive electrode active material layer includes the aforementioned positive electrode active material and may further include a binder, a conductive material, a dispersant, and / or a solid electrolyte.

[0129] The binder improves the bonding properties between the positive electrode active material particles and the bonding properties 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, acrylic styrene-butadiene rubber, epoxy resin, and nylon, but are not limited to these.

[0130] Based on the total weight of the positive electrode active material layer, the binder content in the positive electrode active material layer can be from about 1 wt% to about 5 wt% or from about 0.5 wt% to about 3 wt%.

[0131] Conductive materials are included to provide electrode conductivity. Any conductive material may be used as a conductive material unless it causes a chemical change. Examples of conductive materials may include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metallic materials including metal powders or fibers of copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof. In the positive electrode active material layer, the content of conductive material may be from about 0.1 wt% to about 5 wt% or from about 0.3 wt% to about 3 wt%, based on the total weight of the positive electrode active material layer.

[0132] The content of solid electrolyte in the positive electrode active material layer can be from about 0 wt% to about 35 wt%, for example, from about 0.1 wt% to about 35 wt%, from about 1 wt% to about 35 wt%, from about 5 wt% to about 30 wt%, from about 8 wt% to about 25 wt%, or from about 10 wt% to about 20 wt%. A detailed description of the type of solid electrolyte will be described in the subsequent description of all-solid-state batteries.

[0133] Aluminum foil can be used as a positive collector, but this disclosure is not limited thereto.

[0134] negative electrode

[0135] The negative electrode for an all-solid-state battery may include, for example, a current collector and a layer of negative electrode active material on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0136] The negative electrode active material may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, or a transition metal oxide.

[0137] The material that reversibly intercalates / deintercalates lithium ions may include, for example, crystalline carbon, amorphous carbon, or a combination thereof as a carbon-based negative electrode active material. The crystalline carbon may be amorphous, or natural or artificial graphite in the form of flakes, scales, spheres, or fibers. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbonized products, and calcined coke, etc.

[0138] The lithium metal alloy includes an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0139] The material capable of doping / de-doping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (where 0 < x < 2), a 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 a combination thereof, but not Si), and the Sn-based negative electrode active material may include Sn, SnO2, a 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 a combination 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 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 a combination thereof.

[0140] The silicon-carbon composite can be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles, and an amorphous carbon coating disposed on the surface of the core. The crystalline carbon can be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon can be coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or polymer resins such as phenolic resins, furan resins, or polyimide resins. In this case, based on the total weight of the silicon-carbon composite, the content of silicon particles can be from about 10 wt% to about 50 wt%. Additionally, based on the total weight of the silicon-carbon composite, the content of crystalline carbon can be from about 10 wt% to about 70 wt%, and based on the total weight of the silicon-carbon composite, the content of amorphous carbon can be from about 20 wt% to about 40 wt%. Furthermore, the thickness of the amorphous carbon coating can be from about 5 nm to about 100 nm. The average particle size (D50) of the silicon particles can be from about 10 nm to about 20 μm. The average particle size (D50) of the silicon particles is preferably from about 10 nm to about 200 nm. Silicon particles can exist in an oxidized form, and in this case, the atomic ratio of Si:O in the silicon particles, indicating the degree of oxidation, can be a weight ratio of about 99:1 to about 33:66. The silicon particles can be SiO₂. x Particles, and in this case, SiO x The range of x can be greater than about 0 and less than about 2. In this specification, unless otherwise defined, the average particle size (D50) indicates the diameter of particles that constitute about 50% of the cumulative volume in the particle size distribution.

[0141] Si-based or Sn-based anode active materials can be mixed with carbon-based anode active materials. When mixing and using Si-based or Sn-based anode active materials and carbon-based anode active materials, the mixing ratio can be from about 1:99 to about 90:10 by weight.

[0142] In the negative electrode active material layer, based on the total weight of the negative electrode active material layer, the amount may include the negative electrode active material in an amount of approximately 95 wt% to approximately 99 wt%.

[0143] In one embodiment, the negative electrode active material layer further includes a binder and optionally further includes a conductive material. Based on the total weight of the negative electrode active material layer, the binder content in the negative electrode active material layer can be from about 1 wt% to about 5 wt%. Alternatively, when further including a conductive material, the negative electrode active material layer may include about 90 wt% to about 98 wt% of negative electrode active material, about 1 wt% to about 5 wt% of binder, and about 1 wt% to about 5 wt% of conductive material.

[0144] The binder is used to ensure that the negative electrode active material particles adhere sufficiently to each other, and also to adhere 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.

[0145] Examples of water-insoluble adhesives include polyvinyl chloride, carboxylated polyvinyl chloride, fluorinated polyethylene, ethylene oxide-containing polymers, ethylene-propylene copolymers, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof.

[0146] Water-soluble adhesives may include rubber adhesives or polymeric resin adhesives. Rubber adhesives may be selected from styrene-butadiene rubber, acrylic 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.

[0147] 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 cellulose-based compound, one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts may be mixed and used. As an alkali metal, Na, K, or Li may be used. Based on 100 parts by weight of the negative electrode active material, the amount of thickener used may be from about 0.1 parts by weight to about 3 parts by weight.

[0148] Conductive materials are included to provide electrode conductivity. Any conductive material can be used as a conductive material unless it causes a chemical change. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metallic materials including metal powders or fibers of metals such as copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0149] Negative current collectors 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.

[0150] On the other hand, the negative electrode used in all-solid-state batteries can be, for example, a precipitated negative electrode. A precipitated negative electrode is a negative electrode in which no negative electrode active material is present during the assembly of the electrochemical battery, but lithium metal or the like is precipitated during the charging of the electrochemical battery and used as the negative electrode active material. Figure 4B This is a schematic cross-sectional view of an all-solid-state battery including a deposited negative electrode. (Reference) Figure 4BThe precipitated negative electrode 400' may include a negative current collector 401 and a negative electrode catalyst layer 405 disposed on the negative current collector 401. A rechargeable lithium battery having this precipitated negative electrode 400' begins initial charging without a negative electrode active material, and during charging, a high-density lithium metal or the like precipitates between the negative current collector 401 and the negative electrode catalyst layer 405, forming a lithium metal layer 404, which can be used as a negative electrode active material. Correspondingly, in an all-solid-state battery that exceeds one charge, the precipitated negative electrode 400' may include a negative current collector 401, a lithium metal layer 404 on the negative current collector 401, and a negative electrode catalyst layer 405 on the lithium metal layer 404. The lithium metal layer 404 refers to a layer of lithium metal or the like precipitated during the charging of the electrochemical battery, and may be called a metal layer or a negative electrode active material layer, etc., and functions as a negative electrode active material.

[0151] The negative electrode catalyst layer 405 may include metal and / or carbon materials that act as catalysts.

[0152] The metal may include gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or combinations thereof, and may consist of an alloy selected from one or more of these. The metal included in the negative electrode catalyst layer 405 may have an average particle size (D50) of less than or equal to about 4 μm, for example, from about 10 nm to about 4 μm.

[0153] The carbon material may be, for example, crystalline carbon, non-graphite carbon, or a combination thereof. Crystalline carbon may be, for example, at least one selected from natural graphite, artificial graphite, mesophase carbon microspheres, and combinations thereof. Non-graphite carbon may be at least one selected from carbon black, activated carbon, acetylene black, Tenca black, Ketjen black, and combinations thereof.

[0154] When the negative electrode catalyst layer 405 comprises a metal and a carbon material, the metal and carbon material may be mixed, for example, in a weight ratio of about 1:10 to about 2:1. This can effectively promote the precipitation of lithium metal and improve the characteristics of the all-solid-state battery. The negative electrode catalyst layer may include, for example, a carbon material on which a catalyst metal is supported, or a mixture of metal particles and carbon material particles.

[0155] The negative electrode catalyst layer 405 may further include a binder, and the binder may be a conductive binder. Additionally, the negative electrode catalyst layer 405 may further include general additives, such as fillers, dispersants, and ion conductors. In some embodiments, the negative electrode catalyst layer 405 may not include a negative electrode active material.

[0156] The negative electrode catalyst layer 405 may have, for example, a thickness of about 1 μm to about 20 μm.

[0157] The precipitated negative electrode 400' may, for example, further include a thin film on the surface of the negative current collector 401, i.e., between the negative current collector 401 and the negative electrode catalyst layer 405. 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, and bismuth, which may be used alone or in alloys of one or more. The thin film may further planarize the precipitated shape of the metal layer and greatly improve the characteristics of the all-solid-state battery. The thin film may be formed, for example, by vacuum deposition, sputtering, and electroplating methods. The thin film may have a thickness of, for example, from about 1 nm to about 500 nm.

[0158] solid electrolyte layer

[0159] The solid electrolyte layer 300 includes a solid electrolyte, which may be an inorganic solid electrolyte, such as a sulfide solid electrolyte or an oxide solid electrolyte; or a solid polymer electrolyte.

[0160] In this embodiment, the solid electrolyte can be a sulfide-based solid electrolyte with excellent ion conductivity. Sulfide-based solid electrolytes can be, 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, and Li2S-SiS2-Li p MO q (p and q are integers and M is P, Si, Ge, B, Al, Ga or In, etc.)

[0161] Sulfide-based solid electrolytes can be obtained, for example, by mixing Li₂S and P₂S₅ in a molar ratio of about 50:50 to about 90:10 or about 50:50 to about 80:20. 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, and B₂S₃ as other components. Mixing can be carried out by mechanical milling or solution methods. Mechanical milling involves placing the starting material and a ball mill, etc., into a reactor and vigorously stirring them to form particles from the starting material. Solution methods involve mixing the starting material in a solvent to obtain a solid electrolyte as a precipitate. Additionally, after mixing, further calcination can be performed. When further calcination is performed, the solid electrolyte can have a fairly rigid crystal structure.

[0162] For example, solid electrolytes can be sulfide solid electrolytes of the sulfide type, such as silver-germanium sulfide. Sulfide solid electrolytes can be, for example, Li... a M b P c S d A e (a, b, c, d, and e are all greater than or equal to about 0 and less than or equal to about 12, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, and I), and specifically, Li3PS4, Li7P3S 11 And Li6PS5Cl, etc. This sulfide solid electrolyte has a temperature close to about 10 at room temperature. -4 S / cm to approximately 10 -2 The high ionic conductivity of S / cm is typical of liquid electrolytes, allowing for the formation of a tight interface between the electrode layer and the solid electrolyte layer without compromising ionic conductivity. All-solid-state rechargeable batteries incorporating this sulfide-based solid electrolyte exhibit improved battery performance, such as rate capacity, coulombic efficiency, and cycle life.

[0163] Sulfide solid electrolytes can be amorphous or crystalline, and can be in a mixed state.

[0164] Besides sulfide materials, solid electrolytes can be oxide-based inorganic solid electrolytes, and may 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)、Pb1-x La x Zr 1-y Ti y O3(PLZT)(0 ≤ x < 1, 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3 - 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), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), Li2O, LiAlO2, Li2O - Al2O3 - SiO2 - P2O^5 - 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.

[0165] The solid electrolyte included in the solid electrolyte layer may be in the form of particles, and its average particle size (D50) may be less than or equal to about 5.0 μm, for example, about 0.5 μm to about 5.0 μm. Such a solid electrolyte can form a dense interface between the positive electrode layer and the solid electrolyte layer without causing a short circuit.

[0166] The solid electrolyte layer may further include a binder. Herein, the binder may include styrene - butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate - type polymers or a combination thereof, but is not limited thereto. The acrylate - type polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate or a combination thereof.

[0167] The solid electrolyte layer can be formed by adding the solid electrolyte to a binder solution, coating it on a base film, and drying the resultant. The solvent of the binder solution may be isobutyl isobutyrate, xylene, toluene, benzene, hexane or a combination thereof. Since the formation process of the solid electrolyte layer is well - known in the art, its detailed description will be omitted.

[0168] The thickness of the solid electrolyte layer may be, for example, about 10 μm to about 150 μm.

[0169] The solid electrolyte layer may further comprise an alkali metal salt and / or an ionic liquid and / or a conductive polymer. For example, the solid electrolyte layer may further comprise a lithium salt and / or an ionic liquid and / or a conductive polymer.

[0170] The lithium salt content in the solid electrolyte layer can be greater than or equal to about 1 M, for example, from about 1 M to about 4 M. In this case, the lithium salt can improve ionic conductivity by increasing the lithium ion mobility of the solid electrolyte layer.

[0171] Lithium salts may include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxaloyl)borate (LiBOB), lithium oxaloyl difluoroborate (LIODFB), lithium difluoro(oxaloyl)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or mixtures thereof. Alternatively, lithium salts can be imide lithium salts, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). Lithium salts can maintain or improve ionic conductivity by appropriately preserving their chemical reactivity with ionic liquids.

[0172] Ionic liquids can refer to salts that are liquid at room temperature or have a melting point at room temperature or lower and are formed solely by ions and melt at room temperature. Ionic liquids can be compounds including: a) cations selected from ammonium cations, pyrrolidineonium cations, pyridinium cations, pyrimidineonium cations, imidazolium cations, piperidinium cations, pyrazolium cations, oxazolineonium cations, pyridazineonium cations, phosphonium cations, thioonium cations, triazolium cations, or combinations thereof; and b) cations 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 - The anion.

[0173] The ionic liquid may, for example, be selected from at least one of the following groups: N-methyl-n-propylpyrrolidone bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidone bis(3-trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, or combinations thereof.

[0174] The weight ratio of solid electrolyte to ionic liquid in the solid electrolyte layer can be from about 0.1:99.9 to about 90:10, for example, from about 10:90 to about 90:10, from about 20:80 to about 90:10, from about 30:70 to about 90:10, from about 40:60 to about 90:10, or from about 50:50 to about 90:10. Solid electrolyte layers satisfying these ranges can maintain or improve ionic conductivity by increasing the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate capacity, etc., of all-solid-state batteries can be improved.

[0175] All-solid-state secondary batteries can be unit 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 unit cells.

[0176] There are no particular limitations on the shape of all-solid-state batteries, and they can be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, and flat. Furthermore, all-solid-state batteries can be used in large batteries used in electric vehicles, etc. For example, all-solid-state batteries can also be used in hybrid vehicles, such as plug-in hybrid electric vehicles (PHEVs). Additionally, they can be used in fields requiring large amounts of energy storage, and can be used in, for example, electric bicycles or power tools.

[0177] The following describes embodiments and comparative examples of the present invention. However, it should be understood that the embodiments are for illustrative purposes and are not intended to limit the invention.

[0178] Example 1

[0179] 1. Preparation of positive electrode active material precursor

[0180] The nickel hydroxide Ni, which will be described later, was synthesized by a coprecipitation method. 0.91 Co 0.09 (OH)₂. Nickel sulfate and cobalt sulfate were used as metallic feedstocks. The reaction system used a batch reactor with an effective reaction volume of 85.5 L and a concentration system that allowed for continuous removal of the solution other than the coprecipitates.

[0181] [First step: 4.5kW / m] 3 [NH4OH 0.25M, pH 11.8 to 12.0, and reaction time of 6 hours]

[0182] First, 0.25M ammonia solution is added to the reactor. At 4.5kW / m³ 3 The reaction was initiated when the metal raw material and the complexing agent (NH4OH) were added at 50°C at 107 ml / min and 25 ml / min, respectively, with stirring power. The reaction proceeded for 6 hours while NaOH was added to maintain the pH. After confirming that the particle size obtained as a result of the reaction continued to decrease for 6 hours to form nuclei, the second step was carried out as follows.

[0183] [Second step: 3.5kW / m] 3 [NH4OH 0.30M, pH 11.8 to 12.0, and reaction time of 15 hours]

[0184] The metal raw material and the complexing agent (NH4OH) were added at rates of 142 ml / min and 33 ml / min, respectively, while maintaining the reaction temperature at 50°C and keeping the complexing agent concentration at 0.30 M. NaOH was added to maintain the pH, and the reaction proceeded for 15 hours. At this point, the stirring power was reduced to 3.5 kW / m. 3 The reaction proceeds below the first step and continues. The reaction is terminated after confirming that the obtained product containing the core and surface layer has an average size of 3.5 μm to 3.8 μm.

[0185] [Post-processing]

[0186] The resulting material was washed and then dried with hot air at approximately 150°C for 24 hours to obtain nickel hydroxide Ni. 0.91 Co 0.09 (OH)2.

[0187] 2. Preparation of positive electrode active material

[0188] The obtained nickel hydroxide was mixed with LiOH at a 1:1 molar ratio, and 1.0 mol% boric acid was added based on 100 mol% nickel hydroxide. Then, the mixture was heat-treated at 725 °C for 10 hours under an oxygen atmosphere to obtain the positive electrode active material (LiNi). 0.91 Co 0.09 O2), wherein boron compounds are coated at the internal grain boundaries and on the surface.

[0189] 3. Manufacturing of the positive electrode

[0190] 85 wt% of the obtained positive electrode active material, 13.5 wt% of the lithium-sulfur silver-germanium ore type solid electrolyte Li6PS5Cl, 1.0 wt% of binder, 0.4 wt% of carbon nanotube conductive material, and 0.1 wt% of dispersant were added to an isobutyl isobutyrate (IBIB) solvent, and 2 mm zirconia balls were added to it. The mixture was then stirred with a Thinky mixer to prepare a slurry. The slurry was coated onto a positive current collector and then dried to fabricate the positive electrode.

[0191] 4. Manufacturing of solid electrolyte layer

[0192] Isobutyl isobutyrate (IBIB) as a binder solution was added to the silver sulfide germanite-type solid electrolyte Li6PS5Cl and then mixed. The mixture was stirred using a Thinky mixer to adjust to a suitable viscosity. After viscosity adjustment, 2 mm zirconia balls were added, and the mixture was stirred again using a Thinky mixer to prepare a slurry. The slurry was cast onto a peelable polyethylene terephthalate (PET) film and dried at room temperature to form a solid electrolyte layer.

[0193] 5. Manufacturing of the negative electrode

[0194] A precipitated negative electrode is prepared by coating a slurry of carbon loaded with Ag as a catalyst onto a negative current collector and then drying it.

[0195] 6. Manufacturing of all-solid-state battery cells

[0196] The positive electrode, negative electrode, and solid electrolyte layer are cut, and after the solid electrolyte is stacked on the positive electrode, the negative electrode is stacked on top of it. The stacked products are sealed into bags and subjected to hot isostatic pressing (WIP) at 500 MPa for 30 minutes at high temperature to obtain an all-solid-state battery cell.

[0197] Example 2

[0198] The positive electrode active material and all-solid-state battery cell were manufactured using the same method as in Example 1, except that aluminum nitrate, as a metal raw material, was further used in the preparation of the positive electrode active material precursor in Example 2 to obtain Ni. 0.945 Co 0.04 Al 0.015 (OH)2, and Ni was used in the preparation of the positive electrode active material in Example 2. 0.945 Co 0.04 Al 0.015 (OH)2 was used as a precursor for the positive electrode active material, and 0.5 mol% boric acid was added to it, followed by heat treatment at 700 °C.

[0199] Comparative Example 1

[0200] The positive electrode active material was prepared according to the same method as in Example 1, except that boric acid was not added during the preparation of the positive electrode active material in Comparative Example 1. The positive electrode active material was mixed with lithium ethoxide and zirconium propoxide in ethanol to form a Li₂O·ZrO₂ type buffer layer on the surface by spray drying, which allows for the recovery of organic solvents without contact with external air. Subsequently, the positive electrode and the all-solid-state battery cell were manufactured according to the same method as in Example 1.

[0201] Comparative Example 2

[0202] The positive electrode active material and the all-solid-state battery cell are manufactured according to the same method as in Example 1, except that the positive electrode active material precursor is prepared according to the following method, and boric acid is not added when preparing the positive electrode active material.

[0203] Ni, as a nickel hydroxide, is synthesized using a continuously stirred tank reactor (CSTR), a commonly used industrial process. 0.91 Co 0.09 (OH)₂. The effective reaction volume is 83 L. Nickel sulfate and cobalt sulfate are used as metal raw materials.

[0204] First, 0.35M ammonia solution is added to the reactor. Then, at a reaction temperature of 50°C, a flow rate of 3.0 kW / m³ is applied. 3 The reaction begins with a stirring power of 1000 rpm, while the metal raw material and complexing agent are injected at 71 ml / min and 25 ml / min, respectively.

[0205] By injecting NaOH to maintain the pH, a precursor of the positive electrode active material was obtained after 30 hours of reaction.

[0206] Comparative Example 3

[0207] In the preparation of the positive electrode active material in Example 1, LiNi without boron compound coating was prepared without adding boric acid.0.91 Co 0.09 Following the O2 active material, boron compounds are coated onto LiNi using conventional methods. 0.91 Co 0.09 On O2 active materials. In other words, LiNi 0.91 Co 0.09 O2 was mixed with 1.0 mol% boric acid, and then subjected to a second heat treatment at 350°C for 8 hours under an oxygen atmosphere to obtain a positive electrode active material with a boron compound coated on its surface. The positive electrode and all-solid-state battery cell were then manufactured according to the same method as in Example 1, except that the obtained positive electrode active material was used as the positive electrode active material.

[0208] Evaluation Example 1: SEM Images

[0209] Figure 5 To show a scanning electron microscope image of the fractured surface of the precursor of the positive electrode active material of Example 1, the precursor has a central porous layer and a surface portion, in which primary particles are radially oriented on the surface of secondary particles. Additionally, as... Figures 6 to 7 The study shows that, due to the porous and easily shrinkable surface, the small primary particles maintain a radially oriented structure after the positive electrode active material is prepared.

[0210] Figure 8 The image shows a cross-sectional photograph of the positive electrode active material synthesized according to Comparative Example 2, which shows that when a common precursor is synthesized without the addition of boron, the primary particles are large and lack radial orientation.

[0211] Evaluation Example 2: Components on the surface of active substances

[0212] Figure 9 These are ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) images. Figure 10 The mass spectrometry results are from ToF-SIMS analysis, and Figure 11 The results are from XPS analysis (X-ray photoelectron spectroscopy).

[0213] like Figure 11 The results show that the BO bond was confirmed by analyzing the binding energy, which was verified by literature review to be a lithium boron oxide.

[0214] Figure 9 The results show that lithium boron oxide is uniformly distributed on the surface of the positive electrode active material through mapping of lithium, boron, and simultaneous mapping of lithium and boron. Additionally, Figure 10 The quality analysis results show that BO2 is abundant.

[0215] Combination Figures 9 to 11As a result, lithium boron compounds were uniformly coated on the surface of the secondary particles of the positive electrode active material, with LiBO2 as the main component.

[0216] Evaluation Example 3: Evaluation of boron content on the surface and at grain boundaries within the positive electrode active material

[0217] The boron content was measured by ICP (Inductively Coupled Plasma) emission spectroscopy analysis of the positive electrode active material prepared in Example 1. 10g of each positive electrode active material was added to 100g of distilled water, stirred for 30 minutes, and then filtered to obtain the positive electrode active material. This washing process completely removed boron from the surface of the positive electrode active material. The recovered positive electrode active material was dried at 130°C for 24 hours, and then the boron content was measured again by ICP emission spectroscopy analysis. This boron content is expressed as the boron content present in the internal portion of the positive electrode active material, i.e., at the grain boundaries. Additionally, the difference between the boron content before and after washing, i.e., the boron content removed by washing, is expressed as the boron content on the surface of the positive electrode active material. In Table 1, the unit ppm can mean 10 -4 wt%, and can mean the ratio of the weight of boron to the total weight of the positive electrode active material.

[0218] Table 1

[0219]

[0220] In Table 1, the boron content on the surface indicates the boron content of the first boron coating portion, and the boron content at the internal grain boundaries indicates the boron content of the second boron coating portion. Referring to Table 1, based on the total weight of the positive electrode active material, the boron content of the first boron coating portion in Example 1 is 0.0755 wt%, and based on the total weight of the positive electrode active material, the boron content of the second boron coating portion is 0.0185 wt%. Furthermore, the weight ratio of the first boron coating portion to the second boron coating portion is calculated to be approximately 80:20. Additionally, the first boron coating portion and the second boron coating portion of Example 2 (where 50% of the boron content from Example 1 is added) are calculated to have a weight ratio of approximately 94:6. Furthermore, Comparative Example 3, using a conventional boron coating, shows that boron is not coated in the internal portion of the secondary particles of the positive electrode active material.

[0221] Evaluation Example 4: Evaluation of Initial Discharge Capacity

[0222] The all-solid-state battery cells according to the embodiments and comparative examples were charged to an upper limit voltage of 4.25V at a constant current of 0.1C and discharged to a discharge cutoff voltage of 2.5V at a constant current of 0.1C at 45°C. The initial discharge capacity was measured, and the results are shown in Table 2. Referring to Table 2, Comparative Example 2, which did not use the positive electrode active material according to the embodiments and did not form a buffer layer, showed a very low initial discharge capacity. However, Example 1 achieved an even higher initial discharge capacity than Comparative Example 1, which formed a buffer layer. In addition, in Comparative Example 3, where boron was coated only on the surface of the secondary particles, the boron acted as a resistor, and thus significantly degraded both the initial charge capacity and the initial discharge capacity.

[0223] Table 2

[0224]

[0225] Evaluation Example 5: Evaluation of Cycle Life Characteristics

[0226] The all-solid-state battery cells of the examples and comparative examples that underwent initial charging and discharging in Evaluation Example 4 were repeatedly charged and discharged 150 times at a constant current of 0.33C within a voltage range of 2.5V to 4.25V at 45°C, and their cycle life characteristics were evaluated. The results showed... Figure 12 (Chinese) Reference Figure 12 Comparative Examples 2 and 3 exhibited a sharp decline in cycle life, but Examples 1 and 2 maintained superior capacity compared to Comparative Example 1, which formed the buffer layer using a conventional method. Accordingly, Examples 1 and 2 demonstrated superior cycle life characteristics.

[0227] Although this disclosure 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.

Claims

1. A positive electrode active material for all-solid-state batteries, comprising lithium-nickel composite oxides, and further comprising: The secondary particles comprise a plurality of primary particles, wherein at least a portion of the primary particles are radially arranged. The first boron coating portion on the surface of the secondary particles, and The second boron coating portion on the surface of the primary particle within the interior portion of the secondary particle.

2. The positive electrode active material according to claim 1, wherein each of the first boron coating portion and the second boron coating portion comprises boron oxide, lithium boron oxide, or a combination thereof.

3. The positive electrode active material according to claim 1, wherein the weight of the first boron coating portion is greater than the weight of the second boron coating portion.

4. The positive electrode active material according to claim 1, wherein the first boron coating portion is included in an amount of 70 wt% to 98 wt% based on the total amount of the first boron coating portion and the second boron coating portion, and the second boron coating portion is included in an amount of 2 wt% to 30 wt%.

5. The positive electrode active material according to claim 1, wherein the content of the first boron coating portion is from 0.02 wt% to 0.3 wt% based on the total weight of the positive electrode active material.

6. The positive electrode active material according to claim 1, wherein the content of the second boron coating portion may be from 0.001 wt% to 0.05 wt% based on the total weight of the positive electrode active material.

7. The positive electrode active material according to claim 1, wherein, based on 100 mol% of the positive electrode active material, the total amount of the first boron coating portion and the second boron coating portion is from 0.1 mol% to 3 mol%.

8. The positive electrode active material according to claim 7, wherein, based on 100 mol% of the positive electrode active material, the total amount of the first boron coating portion and the second boron coating portion is from 0.1 mol% to 1.5 mol%.

9. The positive electrode active material according to claim 1, wherein the primary particles are plate-shaped, and at least a portion of the plate-shaped primary particles have long axes arranged in a radial direction.

10. The positive electrode active material according to claim 9, wherein the plate-shaped primary particles have an average length of 150 nm to 500 nm, an average thickness of 100 nm to 200 nm, and the ratio of the average thickness to the average length is 1:2 to 1:

5.

11. The positive electrode active material according to claim 1, wherein the secondary particles comprise: It includes an internal portion with an irregular porous structure and an external portion with a radially arranged structure.

12. The positive electrode active material according to claim 11, wherein... The inner portion of the secondary particle has a larger pore size than the outer portion. The pore size in the internal portion of the secondary particle is from 150 nm to 1 μm, and The pore size in the outer portion of the secondary particle is less than 150 nm.

13. The positive electrode active material according to claim 1, wherein the secondary particles include openings having a size of less than 150 nm and a depth of less than or equal to 150 nm on the surface facing the center of the inner portion.

14. The positive electrode active material according to claim 1, wherein the lithium-nickel composite oxide is represented by chemical formula 1: [Chemical Formula 1] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2 in, In chemical formula 1, 0.9 ≤ a1 ≤ 1.8, 0.3 ≤ x1 ≤ 1, 0 ≤ y1 ≤ 0.7, and M 1 and M 2 Each is independently selected from Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, Zr and combinations thereof.

15. A method for preparing a positive electrode active material for all-solid-state batteries, comprising: Lithium raw materials, nickel hydroxides, and boron raw materials are mixed, and The heat-treated product is used to obtain the positive electrode active material according to any one of claims 1 to 14.

16. The method of claim 15, wherein the boron raw material content is from 0.1 mol% to 3 mol% based on 100 mol% of the nickel hydroxide.

17. The method of claim 15, wherein the heat treatment is performed at a temperature of 650°C to 850°C for 5 to 20 hours.

18. An all-solid-state battery, comprising: The positive electrode includes the positive electrode active material according to any one of claims 1 to 14; negative electrode; And a solid electrolyte layer between the positive electrode and the negative electrode.

19. The all-solid-state battery according to claim 18, wherein The positive electrode includes a current collector and a positive active material layer on the current collector, the positive active material layer including the positive active material and a solid electrolyte, and The solid electrolyte is included in an amount of 0.1 wt% to 35 wt% based on the total weight of the positive electrode active material layer.

20. The all-solid-state battery according to claim 18, wherein the negative electrode comprises a current collector and a negative electrode active material layer or a negative electrode catalyst layer disposed on the current collector.

21. The all-solid-state battery according to claim 18, wherein The negative electrode includes a current collector and a negative electrode catalyst layer on the current collector, and The negative electrode includes a lithium metal layer formed during the initial charging process between the current collector and the negative electrode catalyst layer.

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