Negative electrode coating and all-solid-state battery including same

Abstract

The present disclosure relates to a negative electrode coating for an all-solid-state battery and an all-solid-state battery including the same, and, for example, the negative electrode coating for an all-solid-state battery includes a metal-carbon composite in which a metal and a carbon-based material are chemically bonded by sulfur, in which the content of sulfate ions (SO42-) measured by negative ion chromatography is about 1,000 ppm to about 10,000 ppm, and the metal-carbon composite is a metal-carbon composite in which the metal-carbon composite is bonded by sulfur. And a root mean square roughness (Sq) of one surface of the negative electrode coating layer is about 0.6 [mu] m or less.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0061246, filed on May 9, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of this disclosure herein relate to negative electrode coatings and all-solid-state batteries including therein. Background Technology

[0004] Recently, in response to industrial demands, significant efforts have been made to develop batteries with high energy density and enhanced safety. For example, lithium-ion batteries are already being used in vehicles and information-related electrical and communication devices. In the automotive sector, safety is of particular importance because malfunctions can lead to problems.

[0005] All-solid-state batteries, which use solid electrolytes instead of liquid electrolytes, are now recommended. All-solid-state batteries do not use flammable organic dispersion media, thus significantly reducing the likelihood of fire or explosion even in the event of a short circuit. Therefore, these all-solid-state batteries offer greater safety than lithium-ion batteries that use liquid electrolytes. Summary of the Invention

[0006] Embodiments of this disclosure provide a negative electrode coating having a uniform (or substantially uniform) thickness.

[0007] Embodiments of this disclosure also provide all-solid-state batteries with improved lifespan characteristics.

[0008] Embodiments of this disclosure provide a negative electrode coating comprising a metal-carbon composite, wherein the metal and carbonaceous materials are chemically bonded via sulfur, wherein sulfate ions (SO42-) are measured by negative ion chromatography. 2- The content is about 1,000 ppm to about 10,000 ppm, and the root mean square roughness (Sq) of one surface of the negative electrode coating is about 0.6 μm or less.

[0009] In embodiments of this disclosure, the negative electrode coating comprises a metal-carbon composite, wherein the metal and carbonaceous materials are chemically bonded via sulfur, and wherein sulfate ions (SO42-) are measured by negative ion chromatography. 2- The content of ) is about 1,000 ppm to about 10,000 ppm, a surface includes protrusions with a diameter of about 20 μm or less, and the content of a surface per unit area (e.g., per 100 μm) is 2 The number of protrusions is greater than about 0 and is about 2 or less.

[0010] In embodiments of this disclosure, the all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte layer between the positive and negative electrodes. The negative electrode layer includes a negative electrode current collector and a negative electrode coating. The negative electrode coating includes a metal-carbon composite, wherein the metal and carbonaceous materials are chemically bonded via sulfur. Sulfate ions (SO42-) are measured by negative ion chromatography. 2- The content of the electrolyte is about 1,000 ppm to about 10,000 ppm, the root mean square roughness (Sq) of one surface is about 0.6 μm or less, and one surface is in contact with the solid electrolyte layer.

[0011] In embodiments of this disclosure, the all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte layer between the positive and negative electrodes. The negative electrode layer includes a negative electrode current collector and a negative electrode coating. The negative electrode coating includes a metal-carbon composite, wherein the metal and carbonaceous materials are chemically bonded via sulfur. Sulfate ions (SO42-) are measured by negative ion chromatography. 2- The content of ) is about 1,000 ppm to about 10,000 ppm, a surface includes protrusions with a diameter of about 20 μm or less, and the content of ) per unit area of ​​a surface (e.g., per 100 μm) is 2 The number of protrusions is greater than about 0 and is about 2 or less, and the solid electrolyte layer includes recesses that contact (e.g., physically contact) the protrusions. Attached Figure Description

[0012] The accompanying drawings are included to provide a further understanding of the subject matter of this disclosure, and are incorporated in and form a part of this specification. The drawings illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the subject matter of this disclosure. In the drawings:

[0013] Figure 1 A cross-sectional view of a battery cell (all-solid-state battery) according to an embodiment of the present disclosure is shown.

[0014] Figure 2 A perspective view showing the negative electrode layer according to an embodiment of the present disclosure;

[0015] Figure 3 To show Figure 2 A magnified view of region M of the negative electrode coating;

[0016] Figure 4 To show Figure 2 A cross-sectional view of region N of the negative electrode coating;

[0017] Figure 5 To show Figure 2 A plan view of region N of the negative electrode coating;

[0018] Figure 6 A plan view showing region N of the negative electrode coating according to a comparative example of the present disclosure;

[0019] Figure 7 A set of images showing the results of transmission electron microscopy (TEM) of the metal-carbon composite according to Example 1 of this disclosure;

[0020] Figure 8 A set of images showing the results of transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) of the metal-carbon composite according to Example 1 of this disclosure;

[0021] Figure 9 An image showing the results of an optical microscope of a negative electrode coating containing the metal-carbon composite according to Example 1 of this disclosure;

[0022] Figure 10 An image showing the results of an optical microscope of the negative electrode coating containing the metal-carbon composite according to Comparative Example 1 of this disclosure;

[0023] Figure 11 An image showing the results of an optical microscope of the negative electrode coating containing the metal-carbon composite according to Comparative Example 2 of this disclosure;

[0024] Figure 12 To show an image of the optical microscope results of the negative electrode coating containing the metal-carbon composite according to Comparative Example 3 of this disclosure; and

[0025] Figure 13 Images illustrating the roughness analysis of a negative electrode coating containing the metal-carbon composite according to Example 1 of this disclosure. Detailed Implementation

[0026] To adequately understand the layout and effects of the subject matter of this disclosure, exemplary embodiments of the disclosure will be described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the embodiments described below, and that this disclosure can be implemented in various suitable forms and with various modifications. The embodiments provided herein are intended to make this disclosure thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0027] In this document, it will be understood that if (for example, when) a component is referred to as being on another component, then that component may be directly on the other component, or an intervening third component may be present. In the accompanying drawings, the thickness of the components may be enlarged for effective description of the technical content of this disclosure. The same reference numerals refer to the same elements throughout.

[0028] Some embodiments described herein will be explained with reference to cross-sectional and / or plan views that may serve as ideal example views of this disclosure. To effectively describe the technical content of this disclosure, the thickness of the film and regions may be enlarged in the drawings. Therefore, the regions presented as examples in the drawings have general characteristics, and the shapes of the illustrated regions can be used to illustrate a given or specific shape of the device region. Therefore, this should not be construed as limiting the scope of this disclosure. Although the terms “first,” “second,” “third,” etc., may be used to describe various components of the various embodiments herein, the component should not be limited by these terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein include their complementary embodiments.

[0029] The terminology used herein is not intended to limit this disclosure, but rather to describe implementation methods. As used herein, the singular form includes the plural form as well as the singular form, unless the context clearly indicates otherwise. In addition to the components mentioned, the meaning of “comprises” and / or “comprising” as used herein does not exclude the presence or addition of one or more other components.

[0030] As used herein, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0031] Unless otherwise specified herein, particle size may be the average particle size. In embodiments, particle size is defined as the average particle size (D). 50 The average particle size (D) indicates the diameter of particles that constitute approximately 50 vol% of the total volume in the particle size distribution. 50 The average particle size (D) can be measured by any suitable method commonly used in the art, for example, by a particle size analyzer, images from a transmission electron microscope (TEM), and / or images from a scanning electron microscope (SEM). In this embodiment, the average particle size (D) is... 50 The average particle size (D) can be measured using a dynamic light scattering measurement device, where data analysis is performed to count the number of particles in each particle size range, and then the average particle size can be calculated. 50 The average particle size (D) can be measured using laser scattering. In an embodiment, laser scattering can be used to measure the average particle size. In measurements using laser diffraction, for example, the target particles are dispersed in a dispersion medium, and a commercially available laser diffraction particle size measuring device (e.g., the MT 3000 available from Microtrac, Ltd.) is introduced, irradiated with ultrasonic waves at approximately 28 kHz at a power of 60 W. The average particle size (D) based on 50% of the particle size distribution in the measuring device can then be calculated. 50 ).

[0032] Unless otherwise specified, chemical names, technical terms, scientific terms, and terms as defined in common dictionaries should be interpreted as having meanings consistent with the context of the relevant field, and not as being interpreted in an ideal or overly formal sense. It will be understood that although the terms first, second, etc., may be used herein to describe certain elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Therefore, without departing from the teachings of this disclosure, a first element may be referred to as a second element. Similarly, a second element may be referred to as a first element.

[0033] As used herein, expressions such as “at least one of…”, “one of…”, “selected from…”, and “selected from…” modify the entire list of elements, but not individual elements of the list, if (e.g., when) before / after a list of elements. As utilized herein, expressions “at least one of A, B, and C” and “one of A, B, C, and combinations thereof” refer to individual components and combinations thereof (e.g., A; B; C; A and B; A and C; B and C; or A, B, and C). For example, “at least one of a to c”, “at least one of a, b, and c”, and “at least one of a, b, and / or c” can indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all a, b, and c, or variations thereof.

[0034] As used herein, alternative language such as “or” is not interpreted as exclusive; for example, “A or B” should be interpreted as including A, B, A+B, etc. Similarly, the term “and / or” includes any and all combinations of one or more related enumerated items. Depending on the context, the symbol “ / ” as used herein may be interpreted as “and” or “or”.

[0035] As used herein, it should be understood that terms such as “including,” “includes,” “having,” “has,” “have,” “comprises,” “comprise,” and / or “comprising” are intended to indicate the presence of the features, quantities, steps, actions, components, parts, ingredients, materials, or combinations thereof disclosed in the specification, and are not intended to exclude the possibility that one or more other features, quantities, steps, actions, components, parts, ingredients, materials, or combinations thereof may be present or added. The term “combination thereof” may include mixtures of components, laminates, composites, copolymers, alloys, blends, and reactants.

[0036] As used herein, unless the context clearly indicates otherwise, singular forms such as “a”, “an” and “the” are intended to include plural forms as well.

[0037] As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively.

[0038] The term “may” is to be understood as “one or more embodiments of this disclosure,” some of which include the described elements, and some of which do not include the elements and / or include alternative elements. Similarly, alternative language such as “or” refers to “one or more” or “some” embodiments of this disclosure, each including the corresponding enumerated items.

[0039] In this context, "consisting essentially of" means that any additional components will not significantly affect the chemical, physical, optical, or electrical properties of the target component.

[0040] Figure 1 A cross-sectional view of an all-solid-state battery 10 according to an embodiment of the present disclosure is shown.

[0041] refer to Figure 1 According to an embodiment, the all-solid-state battery 10 includes a positive electrode layer 100, a negative electrode layer 200 facing the positive electrode layer 100, and a solid electrolyte layer 300 between the positive electrode layer 100 and the negative electrode layer 200. However, the embodiment is not limited to this, and the all-solid-state battery 10 may further include additional functional layers, such as an adhesion enhancement layer, between the positive electrode layer 100 and the solid electrolyte layer 300 or between the negative electrode layer 200 and the solid electrolyte layer 300.

[0042] The positive electrode layer 100 of the embodiment includes a positive electrode current collector 110 and a positive electrode active material layer 120 on the positive electrode current collector 110. The positive electrode active material layer 120 may include a positive electrode active material, a solid electrolyte, a conductive material (e.g., an electrically conductive material), and a binder.

[0043] The positive electrode current collector 110 can provide a reference surface, on which the positive electrode active material layer 120 is provided. The positive electrode current collector 110 may include, for example, plates and / or foils containing indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) and / or alloys thereof.

[0044] And shown to Figure 1Due to differences, the positive electrode current collector 110 may not be provided in the embodiments of this disclosure. In the embodiments, a carbon layer with a thickness of about 0.1 μm to about 4 μm may be further provided between the positive electrode current collector 110 and the positive electrode active material layer 120 to increase the bonding strength between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0045] The positive electrode active material is a material capable of reversibly adsorbing and desorbing lithium ions (e.g., intercalation and deintercalation of lithium ions). The positive electrode active material may include, for example, lithium transition metal compounds (e.g., lithium transition metal oxides), such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide and / or lithium iron phosphate; nickel sulfides; copper sulfides; lithium sulfides; iron oxides; and / or vanadium oxides, but the implementation is not limited thereto. The positive electrode active material may be used alone or in a mixture of two or more types (or classes).

[0046] The lithium transition metal compound is, for example, a compound selected from any of the following: Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2- b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b- c Mn b B c D α(0.90≤a≤1,0≤b≤0.5,0≤c≤0.05,0<α≤2)、Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1,0≤b≤0.5,0≤c≤0.05,0<α<2)、Li a Nor b E c G d O2(0.90≤a≤1,0≤b≤0.9,0≤c≤0.5,0.001≤d≤0.1)、Li a Nor b Co c Mn d G e O2(0.90≤a≤1,0≤b≤0.9,0≤c≤0.5,0≤d≤0.5,0.001≤e≤0.1)、Li a NiG b O2(0.9≤a≤1,0.001≤b≤0.1)、Li a CoG b O2(0.90≤a≤1,0.001≤b≤0.1)、Li a MnG b O2(0.90≤a≤1,0.001≤b≤0.1)、Li a Mn2G b O4(0.90≤a≤1,0.001≤b≤0.1) QO2、QS2、LiQS2、V2O5、LiV2O5、LiIO2、LiVO4、Li 3-f J2(PO4)3(0≤f≤2)、Li 3-fFe2(PO4)3(0 ≤ f ≤ 2) and LiFePO4. In this compound, capital "A" is nickel (Ni), cobalt (Co), manganese (Mn), or a combination thereof; capital "B" is aluminum (Al), nickel (Ni), cobalt (Co), manganese (Mn), chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), rare earth elements, or a combination thereof; capital "D" is oxygen (O), fluorine (F), sulfur (S), phosphorus (P), or a combination thereof; capital "E" is cobalt (Co), manganese (Mn), or a combination thereof; capital "F" is fluorine (F), sulfur (S), phosphorus (P), or a combination thereof; capital "G" is aluminum (Al), chromium (Cr), manganese (Mn), iron (Fe), magnesium (Mg), lanthanum (La), cerium (Ce), strontium (Sr), vanadium (V), or a combination thereof; capital "Q" is titanium (Ti), molybdenum (Mo), manganese (Mn), or a combination thereof; capital "I" is chromium (Cr), vanadium (V), iron (Fe), scandium (Sc), yttrium (Y), or a combination thereof; and capital "J" is vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), or a combination thereof.

[0047] The positive electrode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type (or similar) structure among examples of lithium transition metal oxides. For example, "layered rock salt type (or similar) structure" means such a structure in which oxygen atom layers and metal atom layers are regularly alternately arranged in the <111> direction of a cubic rock salt type (or similar) structure, and as a result, each atom layer forms a two-dimensional plane. "Cubic rock salt type (or similar) structure" means a sodium chloride (NaCl) type (or similar) crystal structure as a type (or similar), and for example, a structure in which the face-centered cubic (fcc) lattices formed by corresponding anions and cations are offset by 1 / 2 of the ridge of a unit lattice from each other. The lithium transition metal oxide having the layered rock salt type (or similar) structure may be a ternary lithium transition metal oxide, such as LiNi x Co y Al z O2 (NCA) or LiNi x Co y Mn z O2 (NCM) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). If (for example, when) the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt type (or similar) structure, then the all-solid-state battery 10 may have a greater energy density and improved thermal stability.

[0048] The compounds included in the positive electrode active material can be coated. The positive electrode active material can also be used as a mixture of the compounds and the coated compound. In embodiments, the coating added to the surface of the positive electrode active material may include, for example, oxides, hydroxides, hydroxyoxides, oxycarbonates, and / or basic carbonates of the following coating elements. The compound forming the coating may be amorphous and / or crystalline. The coating elements included in the coating may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating may include, for example, Li₂O-ZrO₂ (LZO). The coating can be formed using any suitable method that does not adversely affect the physical properties of the positive electrode active material. For example, spraying and / or dipping methods can be used to form the coating.

[0049] If (for example, when) the positive electrode active material includes nickel (Ni) (such as ternary lithium transition metal oxides (such as NCA and / or NCM)), the capacity density of the all-solid-state battery 10 increases, thus reducing metal dissolution of the positive electrode active material in the state of charge. Consequently, the all-solid-state battery 10 can have improved cycle characteristics in the state of charge. In this embodiment, "cycle characteristics" is a characteristic indicating the degree of degradation of the all-solid-state battery 10 due to charging / discharging, and in an all-solid-state battery 10 with high cycle characteristics, the degree of degradation caused by charging / discharging may be insignificant, while in an all-solid-state battery 10 with low cycle characteristics, the degree of degradation caused by charging / discharging may be significant.

[0050] The shape of the positive electrode active material may include, for example, particulate shapes, such as spheres and / or ellipsoids. There are no particular limitations on the particle size and content of the positive electrode active material.

[0051] Solid electrolytes may include sulfide-based solid electrolytes with excellent lithium-ion conductivity. Sulfide-based solid electrolytes may include, for example, at least one selected from the following: Li₂S-P₂S₅, Li₂S-P₂S₅-LiX (where X is a halogen element), 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, Li₂S-P₂S₅-Z. m S n (where m and n are positive numbers, and uppercase "Z" is selected from Ge, Zn, and / or Ga), Li2S-GeS2, Li2S-SiS2-Li p MO q(Where p and q are positive numbers, and "M" is selected from P, Si, Ge, B, Al, Ga, and / or In, for example, Li2S-SiS2-Li3PO4), Li 7- x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x (0≤x≤2).

[0052] Sulfide-based solid electrolytes may contain, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x A sulfide-germanium ore type compound containing at least one of (0≤x≤2). In embodiments, the sulfide solid electrolyte may be a sulfide-germanium ore type compound (sulfide-germanium ore type solid electrolyte) containing at least one of, for example, Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0053] In this embodiment, the sulfide-based solid electrolyte may contain Li 7-a M a PS 6-c X c A sulfide-germanium ore-type compound with the indices of (0≤a≤2, 0≤c≤2). In embodiments, X may be F, Br, Cl, or a combination thereof. M may be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0054] Australite-type solid electrolytes can have a density of about 1.5 g / cc to about 2.0 g / cc. Australite-type solid electrolytes, if (e.g., when) have a density of about 1.5 g / cc or greater, can result in all-solid-state batteries with reduced internal impedance (e.g., reduced internal resistance) and prevent defects in the solid electrolyte membrane, such as permeation and short circuits caused by lithium dendrite formation (or reduce the likelihood or incidence of such defects). The solid electrolyte can have an elastic modulus, for example, from about 15 GPa to about 35 GPa.

[0055] The solid electrolyte included in the positive electrode active material layer 120 may have a smaller average (median) particle size (D) than the solid electrolyte included in the solid electrolyte layer 300. 50 For example, the average (median) particle size (D) of the solid electrolyte included in the positive electrode active material layer 120. 50 The average (median) particle size (D) of the solid electrolyte included in the solid electrolyte layer 300 can be used. 50 The average (median) particle size is approximately 90% or less, approximately 80% or less, approximately 70% or less, approximately 60% or less, approximately 50% or less, approximately 40% or less, approximately 30% or less, or approximately 20% or less. In the embodiment, the average (median) particle size (D...) 50 The median diameter can be measured using a laser particle size analyzer.

[0056] The positive electrode active material layer 120 may include a conductive material (e.g., an electrically conductive material). The conductive material has electrical conductivity (e.g., electrical conductivity) without causing chemical changes (or substantially not causing undesirable chemical changes) in the all-solid-state battery 10, thus increasing the conductivity (e.g., electrical conductivity) of both the positive electrode active material and the solid electrolyte. The conductive material may include carbon-based materials. The conductive material may include, for example, at least one selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0057] The positive electrode active material layer 120 may further include an adhesive. The adhesive may bind the positive electrode active material, solid electrolyte, and conductive material contained in the positive electrode active material layer 120, and may include materials designed to improve adhesion strength with the positive electrode current collector 110. The adhesive may include, for example, polyvinylidene fluoride, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and / or polymethyl methacrylate.

[0058] The positive electrode active material layer 120 may include about 85 to about 92 parts by weight of positive electrode active material relative to 100 parts by weight of positive electrode active material, solid electrolyte, conductive material, and binder. The positive electrode active material layer 120 may include about 0.5 to about 1.5 parts by weight of adhesive relative to 100 parts by weight of positive electrode active material, solid electrolyte, conductive material, and binder.

[0059] The positive electrode active material layer 120 may include a conductive material in an amount of about 1 to about 50 parts by weight relative to 100 parts by weight of the solid electrolyte. If, for example, the conductive material is included in the positive electrode active material layer 120 in an amount of less than about 1 part by weight relative to 100 parts by weight of the solid electrolyte, the proportion of conductive material decreases, and therefore the positive electrode active material layer 120 may have reduced conductivity. If, for example, the conductive material is included in the positive electrode active material layer 120 in an amount of more than 50 parts by weight relative to 100 parts by weight of the solid electrolyte, the proportion of conductive material is too high, and therefore a coating covering the surface of the solid electrolyte may not be properly formed.

[0060] In addition to the positive electrode active material, solid electrolyte, conductive material and binder mentioned above, the positive electrode active material layer 120 may further include additives such as fillers, coating agents, dispersants and ion conductors.

[0061] The solid electrolyte layer 300 is located between the positive electrode layer 100 and the negative electrode layer 200, and includes a sulfide-based solid electrolyte with excellent lithium-ion conductivity. The solid electrolyte included in the solid electrolyte layer 300 may be the same as or different from any material that may be included in the solid electrolyte contained in the aforementioned positive electrode active material layer 120.

[0062] The solid electrolyte layer 300 of the embodiment may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte can be prepared by melting-quenching and / or mechanically grinding initial raw materials (e.g., Li₂S, P₂S₅). In the embodiment, the resulting product may subsequently be heat-treated. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In the embodiment, the solid electrolyte may include at least sulfur (S), phosphorus (P), and lithium (Li) as component elements in the aforementioned sulfide-based solid electrolyte material. For example, the solid electrolyte may be a material containing Li₂S-P₂S₅. If, for example, a material containing Li₂S-P₂S₅ is used as the sulfide-based solid electrolyte material forming the solid electrolyte, the molar ratio of Li₂S to P₂S₅ (Li₂S:P₂S₅) is, for example, in the range of about 50:50 to about 90:10.

[0063] Sulfide-based solid electrolytes may contain, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I x A sulfide-germanium ore-type compound containing at least one of the following (0≤x≤2). In embodiments, the sulfide solid electrolyte may be a sulfide-germanium ore-type compound containing at least one of, for example, Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0064] In this embodiment, the sulfide-based solid electrolyte may contain Li 7-a M a PS 6-c X c A sulfogermanium-type compound with the properties (0≤a≤2, (0≤c≤2)). In embodiments, X may be F, Br, Cl, or a combination thereof. M may be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0065] Australite-type solid electrolytes can have densities ranging from about 1.5 g / cc to about 2.0 g / cc. Australite-type solid electrolytes, if (e.g., when) have a density of about 1.5 g / cc or greater, can enable all-solid-state batteries to have reduced internal impedance (e.g., reduced internal resistance) and prevent defects in the solid electrolyte film, such as permeation and short circuits caused by lithium dendrite formation (or reduce the likelihood or occurrence of such defects). The solid electrolyte has an elastic modulus, for example, from about 15 GPa to about 35 GPa.

[0066] The solid electrolyte layer 300 may further include a binder. The binder included in the solid electrolyte layer 300 may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and / or polyethylene, but the embodiments are not limited thereto. The binder of the solid electrolyte layer 300 may be the same as or different from the binder included in the positive electrode active material layer 120 or the binder included in the negative electrode coating 220.

[0067] Reference Figure 2 The negative electrode layer 200 is described in more detail.

[0068] In an embodiment, a carbon layer designed to improve adhesion between the negative electrode coating 220 and the solid electrolyte layer 300 may be further included.

[0069] negative electrode layer

[0070] Figure 2 A cross-sectional view of the negative electrode layer 200 according to an embodiment of the present disclosure is shown.

[0071] refer to Figure 2 The negative electrode layer 200 includes a negative electrode current collector 210 and a negative electrode coating 220 on the negative electrode current collector 210.

[0072] The negative electrode current collector 210 may provide a reference surface on which the negative electrode coating 220 is provided. For example, the negative electrode current collector 210 may comprise a material that does not react with lithium (e.g., does not form an alloy or compound with lithium). Materials constituting the negative electrode current collector 210 may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and / or nickel (Ni), but are not necessarily limited thereto, and any suitable material commonly used in the art as an electrode current collector may be used. The negative electrode current collector may have a thickness of about 1 μm to about 20 μm (e.g., about 5 μm to about 15 μm, or for example, about 7 μm to about 10 μm).

[0073] The negative electrode current collector 210 may be composed of one of the aforementioned metals, or may comprise an alloy of two or more metals. The negative electrode current collector 210 may be in the form of, for example, a plate and / or foil. In some embodiments, the negative electrode current collector 210 may not be provided.

[0074] If, for example, the all-solid-state battery 10 is charged, the negative electrode coating 220 allows lithium metal to grow between the negative electrode coating 220 and the negative electrode current collector 210. In an embodiment, if, for example, the all-solid-state battery 10 is charged, the negative electrode coating 220 may form an alloy with the lithium therein and / or allow lithium metal to grow therein. The negative electrode coating 220 can serve as a protective layer for the lithium metal and also inhibits or reduces the deposition and growth of lithium dendrites.

[0075] The negative electrode coating 220 may have a smaller thickness than the positive electrode active material layer 120. The thickness of the negative electrode coating 220 may be, for example, about 50% or less, about 40% or less, about 30% or less, about 20% or less, about 10% or less, or about 5% or less of the thickness of the positive electrode active material layer 120. The negative electrode coating 220 may have a thickness of, for example, about 1 μm to about 20 μm, about 5 μm to about 20 μm, about 5 μm to about 10 μm, or about 5 μm to about 7 μm. Figure 4 The negative electrode coating 220 can have a thickness of approximately 10 μm (TK3). Figure 4 If, for example, the negative electrode coating 220 is too thin, lithium dendrites between the negative electrode coating 220 and the negative electrode current collector 210 will damage the negative electrode coating 220, and this can lead to degraded cycle characteristics of the all-solid-state battery 10. If, for example, the negative electrode coating 220 is too thick, the all-solid-state battery 10 will have reduced energy density and greater internal impedance (e.g., greater internal resistance) due to the negative electrode coating 220, and this can also lead to degraded cycle characteristics of the all-solid-state battery 10.

[0076] In an embodiment, a carbon layer designed to improve adhesion between the negative electrode coating 220 and the solid electrolyte layer 300 may be further included.

[0077] Reference Figures 3-5 The negative electrode coating 220 is described in more detail.

[0078] negative electrode coating

[0079] Figures 3-5 A view showing the negative electrode coating 220. Figure 3 An enlarged view of region M of the negative electrode coating 220 is shown. Figure 4 For along Figure 2 A cross-sectional view of region N of the negative electrode coating 220 taken from line B-B'. Figure 5 To show Figure 2 Plan view of region N of the negative electrode coating 220.

[0080] refer to Figure 3 The negative electrode coating 220 may include a metal-carbon composite CPL. The metal-carbon composite CPL may include metal MET, carbon-based material CBM, and sulfur (S).

[0081] For example, the metal-carbon composite CPL may include at least one metal MET selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), magnesium (Mg), germanium (Ge), copper (Cu), indium (In), nickel (Ni), bismuth (Bi), tin (Sn), and zinc (Zn). The metal MET can improve the conductivity of the negative electrode layer 200. For example, the metal MET can form an alloy with lithium and form a lithium deposition layer on the underside of the negative electrode coating 220.

[0082] The metal MET can be nanoparticles. For example, the metal MET can have a particle size of about 5 nm to about 80 nm. For example, the particle size can indicate the diameter measured by randomly selecting about 30 metal METs on an electron micrograph of a metal-carbon composite CPL. The metal MET can have a crystal size of about 30 nm to about 60 nm or about 50 nm to about 60 nm. For example, the crystal size can be analyzed using X-ray diffraction (XRD). If, for example, the particle size and crystal size of the metal MET meet the above ranges, the current density in the negative electrode coating 220 can be uniform (or substantially uniform), and the all-solid-state battery including the negative electrode coating can have a longer lifetime.

[0083] Relative to the total weight of the metal-carbon composite CPL, the metal-carbon composite CPL may contain about 3 wt% to about 40 wt%, about 5 wt% to about 40 wt%, about 10 wt% to about 40 wt%, about 12 wt% to about 40 wt%, about 12 wt% to about 20 wt%, or about 12 wt% to about 15 wt% of metal MET. If, for example, the content of metal MET meets the above ranges, then if, for example, the all-solid-state battery is charged, lithium ions released from the positive electrode active material move toward the negative electrode layer 200, so that a lithium deposition layer can be substantially formed between the negative electrode current collector 210 and the negative electrode coating 220.

[0084] Carbon-based materials (CBMs) can be amorphous carbon, crystalline carbon, or mixtures thereof. For example, carbon-based CBMs in metal-carbon composites (CPLs) may include π-π bonds (pi-pi bonds).

[0085] Amorphous carbon may include, for example, carbon black, acetylene black, superconducting acetylene black, furnace black, Ketjen black, activated carbon, or combinations thereof. Carbon black may include, for example, Super P (Timcal).

[0086] Amorphous carbon can be a single particle or an aggregate in the form of secondary particles in which primary particles are assembled (e.g., aggregated). If (e.g., when) amorphous carbon is a single particle, it can be an amorphous carbon particle with an average particle size of about 100 nm or smaller (e.g., about 10 nm to about 100 nm).

[0087] In an embodiment, if (for example, when) amorphous carbon is an aggregate, the primary particles may have a particle size of about 20 nm to about 100 nm, and the secondary particles may have a particle size of about 1 μm to about 20 μm.

[0088] For example, primary particles may have a particle size of about 20 nm or larger, about 30 nm or larger, about 40 nm or larger, about 50 nm or larger, about 60 nm or larger, about 70 nm or larger, about 80 nm or larger, or about 90 nm or larger and about 100 nm or smaller, about 90 nm or smaller, about 80 nm or smaller, about 70 nm or smaller, about 60 nm or smaller, about 50 nm or smaller, about 40 nm or smaller, or about 30 nm or smaller.

[0089] For example, secondary particles may have a particle size of about 1 μm or larger, about 3 μm or larger, about 5 μm or larger, about 7 μm or larger, about 10 μm or larger, or about 15 μm or larger and about 20 μm or smaller, about 15 μm or smaller, about 10 μm or smaller, about 7 μm or smaller, about 5 μm or smaller, or about 3 μm or smaller.

[0090] For example, primary particles may be in the shape of a sphere, an ellipse, a plate, or a combination thereof. In another example, primary particles may be in the shape of a sphere, an ellipse, or a combination thereof.

[0091] Crystalline carbon may include, for example, natural graphite, artificial graphite, carbon nanotubes, graphene, or combinations thereof. Crystalline carbon may be amorphous, plate-like, sheet-like, spherical, and / or fibrous.

[0092] In some embodiments, the metal-carbon composite CPL may include a composite of carbon black and silver (Ag).

[0093] Relative to the total weight of the metal-carbon composite CPL, the metal-carbon composite CPL may contain about 60 wt% to about 97 wt%, about 60 wt% to about 95 wt%, about 60 wt% to about 90 wt%, about 60 wt% to about 88 wt%, about 80 wt% to about 88 wt%, or about 85 wt% to about 88 wt% of carbon-based material CBM. If (e.g., when) the content of carbon-based material CBM meets the above ranges, then if (e.g., when) the all-solid-state battery is charged, a lithium deposition layer can be substantially formed between the negative electrode current collector 210 and the negative electrode coating 220.

[0094] In a metal-carbon composite (CPL), the metal (MET) and carbonaceous material (CBM) are chemically bonded via sulfur (S). For example, the metal MET and carbonaceous material CBM in a CPL are not simply physically mixed or assembled, but rather chemically bonded. The chemical bond between the metal MET and the carbonaceous material CBM can be a sulfur (S) bond. For example, a sulfur (S) bond can include a covalent bond between the carbonaceous material CBM and sulfur (S) and a covalent bond between sulfur (S) and the metal MET. For example, a metal-carbon composite (CPL) can include a covalent bond between the carbonaceous material CBM and sulfur (S) as well as a covalent bond between sulfur (S) and the metal MET.

[0095] Chemical bonds via sulfur (S) can be obtained by using sulfur as a raw material in the process for preparing metal-carbon composites (CPLs).

[0096] The bond strength formed by the chemical bonds of sulfur (S) between the metal MET and the carbonaceous material CBM in the metal-carbon composite CPL is greater than that of a physical bond, and can effectively prevent the metal MET and the carbonaceous material CBM from separating (e.g., when) preparing the negative electrode coating 220 (or can reduce the likelihood, extent, or occurrence of separation between the metal MET and the carbonaceous material CBM). In embodiments, the metal MET can be uniformly (or substantially uniformly) dispersed in the metal-carbon composite CPL by the sulfur (S) uniformly (or substantially uniformly) distributed in the carbonaceous material CBM.

[0097] For example, chemical bonds through sulfur (S) can be determined in spectra obtained by X-ray photoelectron spectroscopy (XPS) analysis of metal-carbon complex CPL.

[0098] For example, if (for instance, when) the metal MET is silver (Ag), then in the S2p spectrum obtained by XPS analysis, there may be a peak in the binding energy range of approximately 160 eV to approximately 162 eV. The peak may correspond to an Ag-S bond.

[0099] The content of sulfur (S) can be analyzed using negative ion chromatography. For example, the content of sulfur (S) can be determined from sulfur ions (such as SO42-) analyzed by negative ion chromatography. 2- The content of ) is obtained. The sulfide ions in this article refer to sulfate ions (such as SO42-) 2- Sulfate ions exist in the form of ions. For example, sulfate ions (SO42-) can be detected by ion chromatography by burning a sample (i.e., a metal-carbon complex CPL) and collecting the gas in a trapping solution, or by oxidizing a sample (i.e., a metal-carbon complex CPL) with an oxidant. 2- Based on the detection of sulfate ions (SO4). 2-The concentration of sulfate ions (SO42-) can be used to determine the sulfur content in the sample (i.e., the metal-carbon composite CPL). Specifically, the concentration of sulfate ions (SO42-) can be measured from the chromatogram. 2- The peak area of ​​the sample (i.e., the metal-carbon composite CPL) can be used to calculate the sulfate concentration. A calibration curve can be created using standard solutions, and the sulfate concentration of the sample (i.e., the metal-carbon composite CPL) can be calculated by matching the peak area of ​​the sample to the calibration curve. The sulfur (S) concentration in the sample (i.e., the metal-carbon composite CPL) can then be determined by multiplying the sulfate concentration by the molar mass ratio of sulfur (32.07) to sulfate (96.06). For example, the sulfate ion (SO4) concentration measured by negative ion chromatography of the metal-carbon composite CPL is... 2- The content of sulfate ions (SO42-) can range from approximately 1,000 ppm to approximately 10,000 ppm. For example, in the metal-carbon composite CPL, the sulfate ion content (SO42-) measured by anion analysis is... 2- The content of sulfur (S) can be from 1,000 ppm to 8,000 ppm, 2,000 ppm to 7,000 ppm, or 3,000 ppm to 6,000 ppm. Correspondingly, the content of sulfur (S) in the metal-carbon composite CPL can be from about 334 ppm to 3,334 ppm, from about 334 ppm to about 2,671 ppm, from about 668 ppm to about 2,337 ppm, or from about 1,002 ppm to about 2,003 ppm. The content of sulfur (S) can be defined as the weight of sulfur (S) relative to the total weight of the metal-carbon composite CPL.

[0100] If, for example, the sulfur (S) content meets the above-mentioned range, then metallic MET can be uniformly (or substantially uniformly) dispersed on the carbonaceous material CBM. In an embodiment, if, for example, the sulfur (S) content meets the above-mentioned range, then the aggregation of the carbonaceous material CBM, the side reactions with metallic MET, and the aggregation of metallic MET can be prevented (or reduced), and a negative electrode coating 220 with a uniform (or substantially uniform) thickness can be provided on the negative electrode current collector 210. Accordingly, if, for example, the all-solid-state battery is charged, then lithium is uniformly (or substantially uniformly) deposited between the negative electrode current collector 210 and the negative electrode coating 220, thereby forming a lithium deposition layer with a uniform (or substantially uniform) thickness and increasing the lifetime of the all-solid-state battery.

[0101] In addition to the metal-carbon composite CPL, the negative electrode coating 220 may further include other additives. The negative electrode coating 220 may further include at least one additive selected from, for example, binders BND, fillers, coating agents, dispersants, and ion-conducting aids.

[0102] For example, as an adhesive BND, water-based adhesives, organic adhesives (i.e., non-water-based adhesives), or combinations thereof can be used. Examples of adhesives that can be used 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, or combinations thereof.

[0103] For example, water-based adhesives may include styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), or combinations thereof. If (for example, when) a water-based adhesive is used, water may be used as a solvent.

[0104] For example, organic binders (i.e., non-aqueous binders) may include polytetrafluoroethylene, polyvinylidene fluoride, etc. If (for example, when) an organic binder (i.e., a non-aqueous binder) is used, N-methylpyrrolidone (NMP) and the like may be used as solvents.

[0105] Metal-carbon composite CPLs can exhibit compressive conductivity of approximately 20 S / cm or greater. For example, metal-carbon composite CPLs can have compressive conductivity ranging from approximately 20 S / cm to approximately 30 S / cm. Compressive conductivity can refer to the conductivity of the powder based on its compressed density, obtained using a conductivity meter (e.g., MCP-PD51, Mitsubishi Chemical). For example, a specific amount of metal-carbon composite CPL can be loaded into a holder, and pressure can be applied to form granules. The mass of the granules can be approximately 2 g. The distance between the electrodes can be approximately 3 mm, the radius of the electrodes can be approximately 0.7 mm, and the radius of the granules can be approximately 10 mm. For each pressure, the resistivity (R) of the granules can be calculated using a four-point probe method. Using the resistance value obtained above, along with correction factors considering the shape and thickness of the granules, the resistivity and conductivity can be calculated.

[0106] Resistivity calculation formula: ρ=G×R, G=3.575×t

[0107] (ρ: resistivity, R: resistance, G: shape correction factor, t: particle thickness)

[0108] σ=1 / ρ

[0109] (σ: conductivity, ρ: resistivity)

[0110] refer to Figures 4-5 The negative electrode coating 220 may include a first region R1 and a second region R2. The second region R2 may indicate the remaining regions other than the first region R1.

[0111] The first region R1 may include a first protrusion PJP1. The first protrusion PJP1 may be formed on a surface of the negative electrode coating 220. The aforementioned surface may be a surface in which the negative electrode coating 220 and the solid electrolyte layer 300 are in contact with each other (e.g., in physical contact). Accordingly, the solid electrolyte layer 300 may include a recessed portion in contact with (e.g., in physical contact) the first protrusion PJP1.

[0112] The first protrusion PJP1 may be a protrusion arising from the aforementioned surface of the negative electrode coating 220. The first region R1 may be defined as a region extending from a surface spaced approximately 0.01 μm apart from the second region R2 in the third direction D3 to a surface that contacts (e.g., physically contacts) the highest point of the first protrusion PJP1 in the third direction D3. The surface that contacts the highest point of the first protrusion PJP1 in the third direction D3 may be parallel to the surface spaced approximately 0.01 μm apart from the second region R2 in the third direction D3.

[0113] The plane of the first protrusion PJP1 may have, for example, a circular shape, an elliptical shape, or an irregular shape. The cross-section of the first protrusion PJP1 may have, for example, a semi-circular shape, a semi-elliptical shape, or an irregular shape. However, the implementation is not limited to the described examples.

[0114] The first diameter DMT1 of the first protrusion PJP1 can be defined as the length of the first protrusion PJP1 in the first direction D1. The length of the first protrusion PJP1 in the first direction D1 is the maximum distance from one point of the first protrusion PJP1 to another point of the first protrusion PJP1, and one point and the other point of the first protrusion PJP1 can be points where the first protrusion PJP1 and the second region R2 are spaced apart by about 0.01 μm in the third direction D3, making surface contact (e.g., physical contact). For example, the diameter DMT1 of the first protrusion PJP1 can be obtained by analyzing the surface of the negative electrode coating 220 defined by the first direction D1 and the second direction D2 using an optical microscope. In an embodiment, the diameter DMT1 of the first protrusion PJP1 can be obtained by analyzing an electron micrograph of the negative electrode coating 220.

[0115] For example, the first diameter DMT1 of the first protrusion PJP1 may be about 20 μm or less. For example, the diameter DMT1 of the first protrusion PJP1 may be about 0 μm to about 20 μm, about 1 μm to about 20 μm, or about 5 μm to about 15 μm.

[0116] The height HGT of the first protrusion PJP1 can be defined as the shortest distance from a surface spaced approximately 0.01 μm apart from the second region R2 in the third direction D3 to a surface that makes contact (e.g., physical contact) with the highest point of the first protrusion PJP1 in the third direction D3. For example, the height HGT of the first protrusion PJP1 can be obtained by analyzing an electron micrograph of the negative electrode coating 220.

[0117] For example, the height HGT of the first protrusion PJP1 can be about 4 μm or less. For example, the height HGT of the first protrusion PJP1 can be about 0 μm to about 4 μm, about 1 μm to about 3 μm, or about 1 μm to about 2 μm.

[0118] If (for example, when) the first diameter DMT1 and height HGT of the first protrusion PJP1 meet the above range, a negative electrode coating 220 with a uniform (or substantially uniform) thickness can be provided on the negative electrode current collector 210, and the all-solid-state battery can have a longer lifespan.

[0119] per unit area of ​​a surface (e.g., per 100 μm) 2 The number of the first protrusions PJP1 of the surface can be about 2 or less. For example, per unit area of ​​a surface (e.g., per 100 μm) 2 The number of first protrusions PJP1 can be about 0 to about 2, or greater than about 0 and about 2 or less. In embodiments, a surface may not substantially include the first protrusions PJP1. For example, per unit area of ​​a surface (e.g., per 100 μm) 2 The number of first protrusions PJP1 can indicate the number of first protrusions PJP1 observed in a randomly selected region (10 μm × 10 μm) on the surface (100 μm × 100 μm) of the negative electrode coating 220. If (e.g., when) the number of first protrusions PJP1 per unit area of ​​a surface (e.g., per 100 μm) 2 When the number of the first protrusions PJP1 meets the above range, a negative electrode coating 220 with a uniform (or substantially uniform) thickness can be provided on the negative electrode current collector 210, and the all-solid-state battery can have a longer lifespan.

[0120] One surface of the negative electrode coating 220 may have a root mean square roughness (Sq) of about 0.6 μm or less. For example, one surface of the negative electrode coating 220 may have a root mean square roughness (Sq) of about 0 μm to about 0.6 μm or about 0.01 μm to about 0.6 μm. For example, the root mean square roughness (Sq) of one surface of the negative electrode coating 220 can be measured using a laser microscope. The root mean square roughness (Sq) of one surface of the negative electrode coating 220 may indicate the average root mean square roughness (Sq) observed in nine randomly selected regions (10 μm × 10 μm) on the surface (100 μm × 100 μm) of the negative electrode coating 220.

[0121] One surface of the negative electrode coating 220 may have a maximum height roughness (Sz) of about 4 μm or less. For example, one surface of the negative electrode coating 220 may have a maximum height roughness (Sz) of about 0 μm to about 4 μm or about 0.01 μm to about 4 μm. For example, the maximum height roughness (Sz) of one surface of the negative electrode coating 220 can be measured using a laser microscope. The maximum height roughness (Sz) of one surface of the negative electrode coating 220 may indicate the average of the maximum height roughness (Sz) observed in nine randomly selected regions (10 μm × 10 μm) on the surface (100 μm × 100 μm) of the negative electrode coating 220.

[0122] If, for example, the root mean square roughness (Sq) and maximum height roughness (Sz) of one surface of the negative electrode coating 220 meet the above ranges, a negative electrode coating 220 with a uniform (or substantially uniform) thickness can be provided on the negative electrode current collector 210, and the all-solid-state battery can have a longer lifespan.

[0123] Figure 6 A plan view of region N of the negative electrode coating containing the metal-carbon composite according to the comparative example of the present disclosure. Sulfate ions (SO42-) in the metal-carbon composite of the comparative example of the present disclosure. 2- The content of the metal can be less than about 1,000 ppm or greater than about 10,000 ppm. Accordingly, the metal can be unevenly dispersed on the carbonaceous material. This can lead to the aggregation of the carbonaceous material, side reactions with the metal, and the aggregation of the metal itself. Consequently, the thickness of the negative electrode coating can be uneven.

[0124] refer to Figure 6According to the comparative examples of this disclosure, the negative electrode coating may include a second raised portion PJP2 on one of its surfaces. One surface may be a surface in which the negative electrode coating and the solid electrolyte layer are in contact with each other (e.g., physical contact). For example, the second diameter DMT2 of the second raised portion PJP2 may vary. The second raised portion PJP2 may include at least one of a first (2-1) raised portion with a diameter of about 20 μm or less, a second (2-2) raised portion with a diameter of about 30 μm to about 70 μm, and a second (2-3) raised portion with a diameter of about 100 μm or greater. The height of the second raised portion PJP2 may vary. For example, the height per unit area of ​​a surface (e.g., per 100 μm) may vary. 2 The number of the (2-1)th protrusion of a surface can be greater than two. For example, the number of protrusions per unit area of ​​a surface (e.g., per 100 μm) can be greater than two. 2 The number of protrusions in the (2-2)th region of a surface can be greater than 0. For example, the number of protrusions per unit area of ​​a surface (e.g., per 100 μm) can be greater than 0. 2 The number of the (2-3)th protrusions can be greater than 0. Accordingly, if (for example, when) an all-solid-state battery is charged, lithium can be deposited unevenly, and the all-solid-state battery can have a short lifespan.

[0125] The metal-carbon composite CPL according to embodiments of this disclosure can be prepared by the following method.

[0126] A first carbonaceous compound and a sulfur feedstock can be mixed. The process can be dry mixing or wet mixing. If (for example, when) a dry mixing process is performed, a sulfur feedstock that is solid at room temperature can be used. If (for example, when) a wet mixing process is performed, a sulfur feedstock that is liquid at room temperature can be used.

[0127] The first carbon-containing compound may include amorphous carbon and / or crystalline carbon.

[0128] The sulfur feedstock may include a second carbon-containing compound and a functional group. The functional group may include sulfur (S). In the sulfur feedstock, the functional group may be chemically bonded to the second carbon-containing compound. The sulfur feedstock may include thiols, sulfides, thiophenes, sulfonic acids, sulfones, sulfoxides, or combinations thereof. For example, the sulfur feedstock may be a thiols.

[0129] For example, thiols may be thioglycolic acid, 1-dodecylthiol, 6-mercapto-1-hexanol, 11-mercapto-1-mercapto-1-undecylol, 2-naphthylthiol, 1,4-benzenedimethylthiol, 4-mercaptobenzoic acid, 1,3-benzenedithiol, or combinations thereof.

[0130] For example, sulfide compounds can be polyphenylene sulfide, carbon disulfide, metal sulfides, or combinations thereof. In metal sulfides, the metal can be Ag, Na, Zn, Fe, or combinations thereof.

[0131] For example, thiophene compounds may be thiophene (C4H4S), 2-methylthiophene, thianaphthalene, 4,6-dimethyldibenzothiophene, or combinations thereof.

[0132] For example, sulfonic acid can be p-toluenesulfonic acid, sodium dodecylbenzenesulfonate, taurine, or a combination thereof.

[0133] For example, sulfone can be dimethyl sulfone, 4,4'-dichlorodiphenyl sulfone, or a combination thereof.

[0134] For example, sulfoxide can be dimethyl sulfoxide, methyl phenyl sulfoxide, or a combination thereof.

[0135] The first carbon-containing compound and the sulfur feedstock may be present in a weight ratio of about 4:1 to about 999:1. For example, the first carbon-containing compound and the sulfur feedstock may be present in a weight ratio of about 4:1 to about 900:1, about 5:1 to about 100:1, or about 5:1 to about 20:1.

[0136] The mixture can be heat-treated. The heat treatment process can be carried out at a temperature of about 70°C to about 110°C. Accordingly, the surface of the first carbon-containing compound can be coated with a sulfur raw material. For example, the first and second carbon-containing compounds can form π-π bonds. The first and second carbon-containing compounds can be used to construct the aforementioned metal-carbon composite carbon material by a process that will be further described elsewhere herein.

[0137] Supported products can be prepared by mixing heat-treated products, metal compounds, reducing agents, and solvents. For example, a loading process can be performed by adding metal compounds and reducing agents to the heat-treated products and solvents. Solvents may include water, ethanol, glycerol, benzene, xylene, or combinations thereof. Reducing agents may include NaBH4, ascorbic acid, trisodium citrate, ethylene glycol, or combinations thereof.

[0138] The metal compound may include metal nitrides, metal sulfates, metal perchlorates, or combinations thereof. The metal may include at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), magnesium (Mg), germanium (Ge), copper (Cu), indium (In), nickel (Ni), bismuth (Bi), tin (Sn), and zinc (Zn). For example, if (e.g., when) the metal is silver (Ag), the metal compound may be AgNO3, Ag2SO4, AgClO4, or combinations thereof.

[0139] The weight ratio of the heat-treated product to the metal compound can be adjusted according to the appropriate or desired content of the metal in the aforementioned metal-carbon composite. The metal compound can be added to achieve metal content in the metal-carbon composite of about 3 wt% to about 40 wt%, about 5 wt% to about 40 wt%, about 10 wt% to about 40 wt%, about 12 wt% to about 40 wt%, about 12 wt% to about 20 wt%, or about 12 wt% to about 15 wt%.

[0140] The amount of reducing agent added can be a suitable or appropriate amount for the reduction reaction of the metal compound, and there are no particular limitations. For example, the amount of reducing agent added relative to the total weight of the metal compound can be from about 10 wt% to about 300 wt%.

[0141] Metal-carbon composites can be prepared by heat treatment of the loaded product. Accordingly, organic matter, solvents, etc., can be removed, and the aforementioned metal-carbon composites can be prepared.

[0142] The heat treatment process can be performed at approximately 100°C to approximately 500°C. For example, the heat treatment process can be performed at approximately 150°C to approximately 500°C, approximately 200°C to approximately 450°C, or approximately 200°C to approximately 400°C. The heat treatment can be performed in a nitrogen atmosphere, an argon atmosphere, or an atmosphere containing a combination thereof. The heat treatment can last for approximately 2 to approximately 20 hours.

[0143] The embodiments of this disclosure will be described in more detail below through examples. However, the examples are merely illustrative of embodiments of this disclosure, and the scope of this disclosure is not limited to the following examples.

[0144] Example 1

[0145] A metal-carbon complex containing silver (Ag) and carbon-based materials, chemically bonded together by sulfur (S), was prepared. Sulfate ions (SO42-) were measured by negative ion chromatography. 2- The content of ) was 3,445 ppm. The metal-carbon complex was prepared as follows.

[0146] Carbon black and 2-naphthyl mercaptan powder were mixed. The mixture was heat-treated at a temperature of 70°C to 110°C. The heat-treated product, AgNO3, NaBH4 reducing agent, and water were mixed to prepare a supported product. The supported product was heat-treated in a nitrogen atmosphere at a temperature of 100°C to 500°C to prepare a metal-carbon composite.

[0147] Example 2

[0148] The metal-carbon complex was prepared in essentially the same manner as in Example 1, except that the sulfate ion (SO4) was used instead of the carbon ion. 2- The content of ) was 4,708 ppm.

[0149] Example 3

[0150] The metal-carbon complex was prepared in essentially the same manner as in Example 1, except that the sulfate ion (SO4) was used instead of the carbon ion. 2- The content of ) was 5,851 ppm.

[0151] Comparative Example 1

[0152] The metal-carbon complex was prepared in essentially the same manner as in Example 1, except that the sulfate ion (SO4) was used instead of the carbon ion. 2- The content of ) was 843 ppm.

[0153] Comparative Example 2

[0154] The metal-carbon complex was prepared in essentially the same manner as in Example 1, except that the sulfate ion (SO4) was used instead of the carbon ion. 2- The content of ) was 10,272 ppm.

[0155] Comparative Example 3

[0156] The metal-carbon complex was prepared in essentially the same manner as in Example 1, except that the sulfate ion (SO4) was used instead of the carbon ion. 2- The content of ) was 22,543 ppm.

[0157] Preparation of negative electrode layer

[0158] A slurry was prepared by mixing a metal-carbon composite, styrene-butadiene rubber, and sodium carboxymethyl cellulose in an aqueous solvent at a weight ratio of 100:6:3.

[0159] The prepared slurry was coated onto a 10 μm thick stainless steel foil current collector and then vacuum dried at 80 °C. The negative electrode coating has a thickness of 10 μm.

[0160] Preparation of solid electrolyte layer

[0161] A sulforaphane-germanium ore type solid electrolyte Li6PS5Cl was mixed with an isobutyl isobutyrate binder solution (solid content: 50 wt%) containing an acrylate polymer containing butyl acrylate; and the mixture was blended. The mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight.

[0162] The mixing process was performed using a Thinky mixer. 2 mm zirconia balls were added to the resulting mixture, and the mixture was stirred again using the Thinky mixer to prepare a slurry. The slurry was cast into a peeled polytetrafluoroethylene membrane and dried at room temperature to prepare a 100 μm thick solid electrolyte layer.

[0163] Preparation of positive electrode layer

[0164] Preparation of positive electrode active material (LiNi) coated with LZO (Li-doped zinc oxide) 0.9 Mn 0.05 Co 0.05 A mixture of O2), sulfosilver germanite-type solid electrolyte Li6PS5Cl, conductive material (carbon nanofibers), and binder (polytetrafluoroethylene) in a weight ratio of 85:15:3:1.5.

[0165] The prepared mixture was coated onto a 10 μm thick aluminum foil current collector and then vacuum dried at 45 °C to prepare the positive electrode layer. The positive electrode active material layer had a thickness of 160 μm.

[0166] Fabrication of all-solid-state batteries

[0167] A negative electrode layer, a solid electrolyte layer, and a positive electrode layer are stacked sequentially, and a pressure of 4 Nm is applied to prepare an all-solid-state battery.

[0168] Evaluation Example 1: Analysis of Metal-Carbon Complexes

[0169] The components and compositions of the metal-carbon complexes of Examples 1-3 and Comparative Examples 1-3 were analyzed. Sulfate ions (SO4) 2- The content of silver (Ag) was analyzed using ion chromatography. The crystal size of silver (Ag) was analyzed using XRD. The content of silver (Ag) was analyzed using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The results are shown in... Figures 7-8 And in Table 1. Figures 7-8 Multiple images of the metal-carbon composite of Example 1, obtained by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), are shown.

[0170] Table 1

[0171]

[0172]

[0173] refer to Figures 7-8 As shown in Table 1, carbon (C), silver (Ag), and sulfur (S) were detected in the metal-carbon composites of Examples 1 to 3. Furthermore, it was determined that the metal-carbon composites of Examples 1 to 3 exhibit excellent compressive conductivity.

[0174] Evaluation Example 2: Surface Analysis of Negative Electrode Coating (1)

[0175] The surface of the negative electrode coating containing the metal-carbon composites according to Examples 1-3 and Comparative Examples 1-3 was analyzed. Surface analysis was performed using an optical microscope. Surface analysis was performed by magnifying the surface of the negative electrode coating 500x and measuring the diameter of the observed protrusions. The results are shown in... Figures 9-12 middle.

[0176] The coating properties of each negative electrode coating prepared using the metal-carbon composite were evaluated based on the diameter of the protrusions, and the results are shown in Table 2. If (e.g., when) only protrusions with a diameter of 20 μm or less are included, the coating properties are evaluated as good. If (e.g., when) protrusions with a diameter of 30 μm to 70 μm are included, the coating properties are evaluated as poor. If (e.g., when) protrusions with a diameter of 100 μm or greater are included, the coating properties are evaluated as worst.

[0177] Table 2

[0178] Metal-carbon complex Coating characteristics Example 1 good Example 2 good Example 3 good Comparative Example 1 Difference Comparative Example 2 worst Comparative Example 3 worst

[0179] refer to Figure 9 On one surface of the negative electrode coating containing the metal-carbon composite according to Example 1, raised portions (PJPs) with a diameter of approximately 10 μm were observed. Per 100 μm of a surface... 2 It includes a raised portion.

[0180] refer to Figure 10 A raised portion (PJP) with a diameter of about 60 μm was observed on a surface containing a negative electrode coating of the metal-carbon composite according to Comparative Example 1.

[0181] refer to Figures 11-12 On one side of the negative electrode coating containing the metal-carbon composite according to Comparative Example 2 and Comparative Example 3, a protrusion (PJP) with a diameter of about 100 μm or larger was observed.

[0182] It was determined that, compared with the negative electrode coating containing the metal-carbon composite according to Comparative Examples 1 to 3, the negative electrode coating containing the metal-carbon composite according to Examples 1 to 3 has a negative electrode coating with uniform thickness and excellent coating characteristics.

[0183] Evaluation Example 3: Surface Analysis of Negative Electrode Coating (2)

[0184] The surface roughness of the negative electrode coatings containing the metal-carbon composites according to Example 1, Comparative Example 1, and Comparative Example 2 was analyzed. The surface roughness of the negative electrode coatings was measured using an Olympus laser microscope OLS4100 (LEXT OLS 4100) according to ISO-25178-2:2012. The surfaces of the negative electrode coatings containing the metal-carbon composites according to Example 1 and Comparative Examples 1 and 2 were magnified 20 times. Nine random regions (10 μm × 10 μm) on the 100 μm × 100 μm surface of each negative electrode coating 220 were selected (see...). Figure 13 The average root mean square roughness (Sq) and the average maximum height roughness (Sz) observed in the above-mentioned areas are shown in Table 3.

[0185] Table 3

[0186] Metal-carbon complex Sq(μm) Sz(μm) Example 1 0.53 3.87 Comparative Example 1 0.75 4.53 Comparative Example 2 1.10 5.76

[0187] It was determined that, compared with the negative electrode coating containing the metal-carbon composite according to Comparative Example 1 and Comparative Example 2, the negative electrode coating containing the metal-carbon composite according to Example 1 has a lower root mean square roughness (Sq) and a lower maximum height roughness (Sz).

[0188] Evaluation Example 4: Lifetime Analysis of All-Solid-State Batteries

[0189] The lifespan of all-solid-state batteries containing the metal-carbon composites according to Examples 1-3 and Comparative Examples 1-3 was evaluated. Lifespan evaluation was performed by placing the all-solid-state batteries in a 60°C thermostat. The batteries were charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.05C for 20 hours until the battery voltage reached 2.5V (first cycle). Subsequently, the batteries were charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V, and then discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V (second cycle). Thereafter, the batteries were charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. Subsequently, the batteries were discharged at a constant current of 0.5C for 2 hours until the battery voltage reached 2.5V (third cycle). Thereafter, the batteries were charged at a constant current of 0.1C for 10 hours until the battery voltage reached 4.25V. The battery was then discharged at a constant current of 1C for 1 hour until the battery voltage reached 2.5V (fourth cycle). Afterward, the battery was charged at a constant current of 0.33C for 3 hours until the battery voltage reached 4.25V. Then, the battery was discharged at a constant current of 0.33C for 3 hours until the battery voltage reached 2.5V (fifth cycle). This cycle was repeated a total of 50 times to assess capacity retention based on the number of cycles.

[0190] Capacity retention (%) = (Discharge capacity after each cycle / Discharge capacity in the first cycle) × 100

[0191] If, for example, the capacity retention rate (%) after 50 cycles is 98% or higher, the lifetime characteristics are assessed as good. If, for example, the capacity retention rate (%) after 50 cycles is less than 98%, the lifetime characteristics are assessed as poor. The results are shown in Table 4.

[0192] Table 4

[0193] Lifetime characteristics Example 1 good Example 2 good Example 3 good Comparative Example 1 Difference Comparative Example 2 Difference Comparative Example 3 Difference

[0194] The all-solid-state battery containing the metal-carbon composite according to Examples 1 to 3 has better lifespan characteristics than the all-solid-state battery containing the metal-carbon composite according to Comparative Examples 1 to 3.

[0195] The negative electrode coating according to embodiments of this disclosure may have a uniform (or substantially uniform) thickness.

[0196] All-solid-state batteries according to embodiments of this disclosure can have excellent lifespan characteristics.

[0197] Terms such as “substantially,” “about,” and “approximately” are used as relative terms rather than terms of degree and are intended to describe the inherent deviation of a measured or calculated value that would be recognized by a person skilled in the art. They may include the stated value and an acceptable range of deviation determined by a person skilled in the art, taking into account the limitations and errors associated with the measurement of that quantity. For example, “about” may refer to one or more standard deviations, or ±30%, ±20%, ±10%, or ±5% of the stated value.

[0198] The numerical ranges disclosed herein include and are intended to include all subranges with the same numerical precision. For example, the range “1.0 to 10.0” is intended to include all subranges (such as, for example, 2.4 to 7.6) that are equal to or greater than 1.0 and equal to or less than 10.0. Therefore, the applicant reserves the right to amend this specification (including the claims) to expressly describe any subranges included within the ranges expressly described herein.

[0199] Although embodiments of the present disclosure have been described above with reference to the accompanying drawings, the present disclosure may be applied in other specific forms without altering the technical concept or essential characteristics thereof. Therefore, it should be understood that the above embodiments are presented as examples in all respects and are not restrictive.

Claims

1. A negative electrode coating for all-solid-state batteries, comprising: Metal-carbon composites, in which the metal and carbon materials are chemically bonded through sulfur. The sulfate ion content, measured by negative ion chromatography, ranged from 1,000 ppm to 10,000 ppm. The root mean square roughness of one surface of the negative electrode coating is 0.6 μm or less.

2. The negative electrode coating for an all-solid-state battery as claimed in claim 1, wherein the metal-carbon composite comprises covalent bonds between the carbon-based material and the sulfur, and covalent bonds between the sulfur and the metal.

3. The negative electrode coating for an all-solid-state battery as claimed in claim 1, wherein the metal-carbon composite contains 3 wt% to 40 wt% metal relative to the total weight of the metal-carbon composite.

4. The negative electrode coating for an all-solid-state battery as claimed in claim 1, wherein the metal comprises at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, magnesium, germanium, copper, indium, nickel, bismuth, tin, and zinc.

5. The negative electrode coating for all-solid-state batteries as claimed in claim 1, wherein the metal has a crystal size of 30 nm to 60 nm.

6. The negative electrode coating for all-solid-state batteries as described in claim 1, wherein the carbon material is amorphous carbon, crystalline carbon, or a mixture thereof.

7. The negative electrode coating for all-solid-state batteries as described in claim 1, further comprising a binder. The adhesive is a water-based adhesive, a non-water-based adhesive, or a combination thereof.

8. The negative electrode coating for all-solid-state batteries as claimed in claim 1, wherein the maximum height roughness of one surface is 4 μm or less.

9. The negative electrode coating for an all-solid-state battery as claimed in claim 1, wherein the negative electrode coating has a thickness of 1 μm to 20 μm.

10. The negative electrode coating for an all-solid-state battery as claimed in claim 1, wherein the metal-carbon composite has a compressive conductivity of 20 S / cm or greater.

11. A negative electrode coating for an all-solid-state battery, comprising a metal-carbon composite, wherein the metal and carbon-based materials are chemically bonded via sulfur. The sulfate ion content, measured by negative ion chromatography, ranged from 1,000 ppm to 10,000 ppm. One surface of the negative electrode coating includes a protrusion with a diameter of 20 μm or less, and Every 100 μm of the surface 2 The number of protrusions is greater than 0 and is 2 or less.

12. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the metal-carbon composite comprises covalent bonds between the carbon-based material and the sulfur, and covalent bonds between the sulfur and the metal.

13. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the metal-carbon composite contains 3 wt% to 40 wt% metal relative to the total weight of the metal-carbon composite.

14. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the metal has a crystal size of 30 nm to 60 nm.

15. The negative electrode coating for an all-solid-state battery as described in claim 11, further comprising a binder. The adhesive is a water-based adhesive, a non-water-based adhesive, or a combination thereof.

16. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the raised portion has a height of 4 μm or less.

17. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the negative electrode coating has a thickness of 1 μm to 20 μm.

18. The negative electrode coating for an all-solid-state battery as claimed in claim 11, wherein the metal-carbon composite has a compressive conductivity of 20 S / cm or greater.

19. An all-solid-state battery, comprising: Positive electrode; negative electrode; as well as A solid electrolyte layer is located between the positive electrode and the negative electrode. The negative electrode layer comprises a negative electrode current collector and a negative electrode coating as described in any one of claims 1 to 18. And one of the surfaces is in contact with the solid electrolyte layer.

20. The all-solid-state battery as described in claim 19, The solid electrolyte layer includes a recessed portion that contacts the protruding portion.

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