Negative electrode for all-solid-state battery and all-solid-state battery

Abstract

A negative electrode for an all-solid-state battery and an all-solid-state battery are disclosed. The negative electrode includes a negative electrode current collector, a first negative electrode coating layer on the negative electrode current collector and including a first metal and a first carbon, and a second negative electrode coating layer on the first negative electrode coating layer and including a second metal and a second carbon. [Delta] G1 represents the Gibbs free energy of the chemical reaction between the first metal and the molten lithium at 250 DEG C. [Delta] G2 represents the Gibbs free energy of the chemical reaction between the second metal and the molten lithium at 250 DEG C. [delta] G1 and [delta] G2 satisfy [delta] G1lt; [delta] G2. A ratio of a thickness of the second negative electrode coating layer to a thickness of the first negative electrode coating layer is from about 0.6 to about 1.4.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0138612, filed on October 11, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments of this disclosure relate to a negative electrode for an all-solid-state battery and an all-solid-state battery, and for example, to an all-solid-state battery including a lithium deposition layer. Background Technology

[0004] Recently, driven by industrial demands, high-energy-density and safe batteries have been actively developed. For example, lithium-ion batteries are being commercialized not only in information-related and communication devices but also in the automotive industry. In the automotive industry, safety is given particular emphasis because it is directly related to human life.

[0005] Recently, all-solid-state batteries have been recommended to use solid electrolytes instead of liquid electrolytes. Because all-solid-state batteries do not use flammable organic dispersion media, the possibility of fire or explosion is significantly reduced, even in the event of a short circuit. Consequently, all-solid-state batteries offer significantly increased safety compared to lithium-ion batteries that use liquid electrolytes. Summary of the Invention

[0006] Embodiments of this disclosure provide all-solid-state batteries with extended lifespan.

[0007] According to embodiments of this disclosure, the negative electrode for an all-solid-state battery may include: a negative electrode current collector; a first negative electrode coating on the negative electrode current collector, wherein the first negative electrode coating comprises a first metal and a first carbon; and a second negative electrode coating on the first negative electrode coating, wherein the second negative electrode coating comprises a second metal and a second carbon. ΔG1 may represent the Gibbs free energy of the chemical reaction between the first metal and molten lithium at 250°C. ΔG2 may represent the Gibbs free energy of the chemical reaction between the second metal and molten lithium at 250°C. ΔG1 and ΔG2 may satisfy the relationship ΔG1 < ΔG2. The ratio of the thickness of the second negative electrode coating to the thickness of the first negative electrode coating may be in the range of about 0.6 to about 1.4.

[0008] According to embodiments of this disclosure, an all-solid-state battery may include: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The negative electrode layer may include: a negative electrode current collector; a first negative electrode coating on the negative electrode current collector, wherein the first negative electrode coating includes a first metal and a first carbon; and a second negative electrode coating on the first negative electrode coating, wherein the second negative electrode coating includes a second metal and a second carbon. The ionic conductivity of the first negative electrode coating may be greater than the ionic conductivity of the second negative electrode coating. The electronic conductivity of the second negative electrode coating may be greater than the electronic conductivity of the first negative electrode coating. The thickness of the first negative electrode coating and the sum of the thicknesses of the second negative electrode coating may be in the range of about 5 μm to about 15 μm.

[0009] According to embodiments of this disclosure, an all-solid-state battery may include: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The negative electrode layer may include: a negative electrode current collector; a first negative electrode coating on the negative electrode current collector, wherein the first negative electrode coating includes a first metal and a first carbon; and a second negative electrode coating on the first negative electrode coating, wherein the second negative electrode coating includes a second metal and a second carbon. ΔG1 may represent the Gibbs free energy of the chemical reaction between the first metal and molten lithium at 250°C. ΔG2 may represent the Gibbs free energy of the chemical reaction between the second metal and molten lithium at 250°C. ΔG1 and ΔG2 may satisfy the relationship ΔG1 < ΔG2. The ratio of the thickness of the second negative electrode coating to the thickness of the first negative electrode coating may be in the range of about 0.6 to about 1.4. Attached Figure Description

[0010] The accompanying drawings, together with the description, illustrate embodiments of the subject matter of this disclosure, and the accompanying drawings, together with the description, serve to explain the principles of embodiments of the subject matter of this disclosure.

[0011] Figure 1 A plan view of an all-solid-state battery according to an embodiment of the present disclosure is shown.

[0012] Figure 2 A cross-sectional view of an all-solid-state battery according to an embodiment of the present disclosure is shown.

[0013] Figure 3 A cross-sectional view of an all-solid-state battery according to an embodiment of the present disclosure is shown.

[0014] Figure 4 A cross-sectional view of a negative electrode for an all-solid-state battery according to an embodiment of the present disclosure is shown.

[0015] Figure 5A and Figure 5B To show as Figure 4The graph depicts electronic conductivity and ionic conductivity as a function of distance.

[0016] Figure 6 A cross-sectional view of a negative electrode for an all-solid-state battery according to an embodiment of the present disclosure is shown. Detailed Implementation

[0017] To fully understand the layout and effects of the subject matter of this disclosure, some embodiments of this disclosure will be described with reference to the accompanying drawings. However, it should be noted that the subject matter of this disclosure is not limited to the exemplary embodiments described below and can be implemented in various suitable forms. Rather, exemplary embodiments are provided merely to disclose embodiments of this disclosure and to enable those skilled in the art to fully understand the scope of this disclosure.

[0018] In this description, it will be understood that if (e.g., when) an element is referred to as being on another element, then the element may be directly on the other element, or an intervening element may exist between them. In the accompanying drawings, the dimensions (e.g., thickness) of some components may be enlarged for effective explanation of the technical content. Throughout the specification, the same reference numerals refer to the same elements.

[0019] Some embodiments detailed in this description will be discussed with reference to cross-sectional and / or plan views, which serve as ideal or schematic example views of this disclosure. In the drawings, the dimensions (e.g., thickness) of layers and regions may be enlarged to effectively explain the technical content. Accordingly, the regions illustrated as examples in the drawings have general characteristics, and the shapes of the regions illustrated as examples in the drawings are examples of the disclosed shapes or specific shapes, but are not intended to limit the scope of this disclosure. It will be understood that although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. The exemplary embodiments explained and illustrated herein include their complementary embodiments.

[0020] Unless otherwise specifically stated in this description, singular expressions may include plural expressions. In implementations, unless otherwise specifically stated, the phrase "A or B" may indicate "A but not B", "B but not A", and "A and B". The terms "comprises" and / or "comprising" as used in this description do not exclude the presence or addition of one or more other components.

[0021] In this description, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0022] Unless otherwise specifically defined in this description, particle size may refer to the average particle size. In embodiments, particle size indicates the average particle size (D) of particles having a cumulative volume of 50 vol% in the particle size distribution. 50 Average particle size (D) 50 The particle size can be measured by any suitable method commonly used in the art, such as by a particle size analyzer, transmission electron microscopy (TEM) images, and / or scanning electron microscopy (SEM) images. In an embodiment, data analysis can be performed using a dynamic light scattering measurement device to count the number of particles for each particle size range, and from this, the average particle size (D) can be calculated. 50 In contrast, laser irradiation methods can be used to measure average particle size (D). 50 In the laser scattering method, target particles are dispersed in a dispersion solvent and introduced into a laser scattering particle measuring device (e.g., MT3000, commercially available from Microtrac, Inc.). The particles are then irradiated with ultrasound at 28 kHz at a power of 60 W. The average particle size (D) is then calculated in the measuring device using a 50 vol% standard of particle size distribution. 50 ).

[0023] Figure 1 A plan view of an all-solid-state battery according to an embodiment of the present disclosure is shown. Figure 2 For along Figure 1 A cross-sectional view taken from line A-A'.

[0024] refer to Figure 1 and Figure 2 The all-solid-state battery 10 according to embodiments of the present disclosure may include a positive electrode layer 100, a negative electrode layer 200 opposite to 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 present disclosure is not limited thereto, 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 and / or an adhesion enhancement layer between the negative electrode layer 200 and the solid electrolyte layer 300.

[0025] The positive electrode layer 100 according to embodiments of the present disclosure may include 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.

[0026] The positive electrode current collector 110 may provide a reference surface on which the positive electrode active material layer 120 is provided. The positive electrode current collector 110 may include plates and / or foils comprising, for example, indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) and / or alloys thereof (e.g., stainless steel).

[0027] and Figure 2 As shown in the previous embodiment, the positive electrode current collector 110 may not be provided in this embodiment. In an embodiment, to increase the adhesion between the positive electrode current collector 110 and the positive electrode active material layer 120, a carbon layer having 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.

[0028] The positive electrode active material layer 120 may include a material capable of reversibly absorbing and desorbing lithium ions. The positive electrode active material may include multiple particles. For example, the positive electrode active material may include lithium transition metal oxides (e.g., 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 this disclosure is not limited thereto. The positive electrode active material may be used alone or in a mixture of two or more substances.

[0029] Lithium transition metal oxides can be, for example, compounds represented by one of the following: Li a A 1-b B b D2 (where 0.90≤a≤1 and 0≤b≤0.5), Li a E 1-b B b O 2-c D c (where 0.90≤a≤1, 0≤b≤0.5, and 0≤c≤0.05), LiE 2-b B b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05), Li a Ni 1-b-c Co b B c D α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2), Li a Ni 1-b-c Co b B cO 2-α F' α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2), Li a Ni 1-b-c Mn b B c D α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α≤2), Li a Ni 1-b-c Mn b B c O 2-α F' α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2), Li a Ni b E c G d O2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, and 0.001≤d≤0.1), Li a Ni b Co c Mn d G e O2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0.001≤e≤0.1), Li a NiG b O2 (where 0.9 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1), Li a CoG b O2 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1), Li a MnG b O2 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1), Li a Mn2G b O4 (where 0.90≤a≤1 and 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3 (where 0≤f≤2), Li 3-fFe2(PO4)3 (where 0 ≤ f ≤ 2) and LiFePO4. In the above compounds, "A" can be Ni, Co, Mn, or a combination thereof, "B" can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof, "D" can be O, F, S, P, or a combination thereof, "E" can be Co, Mn, or a combination thereof, "F'" can be F, S, P, or a combination thereof, "G" can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, "Q" can be Ti, Mo, Mn, or a combination thereof, "I" can be Cr, V, Fe, Sc, Y, or a combination thereof, and "J" can be V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0030] The positive electrode active material can include, for example, a lithium salt of a transition metal oxide having a layered rock salt-type structure among the lithium transition metal oxides discussed above. The term "layered rock salt-type structure" can refer to a structure in which oxygen atom layers and metal atom layers alternate and are regularly arranged in the <111> direction of a cubic rock salt-type structure (e.g., the structure of cubic rock salts), where each atom layer forms a two-dimensional plane. The term "cubic rock salt-type structure" can refer to the sodium chloride (NaCl)-type structure (e.g., the structure of sodium chloride (NaCl) classes) as a type (or kind) of crystal structure, and for example, has a structure provided by staggering the face-centered cubic lattices (FCC) formed by cations and anions by 1 / 2 of the edge (ridge) of the unit lattice. The lithium transition metal oxide having a layered rock salt-type structure can be a ternary lithium transition metal oxide, such as LiNi x Co y Al z O2 (NCA) and / or LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). If (e.g., when) the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt-type structure, then the all-solid-state battery 10 can have an increased energy density and improved thermal stability.

[0031] The compounds included in the positive electrode active material (e.g., a portion of the compound's surface) may be covered by a coating. The positive electrode active material can be used as a mixture of the compound and the compound with the coating applied to its surface. The coating applied to the surface of the positive electrode active material may include oxides, hydroxides, hydroxyoxides, oxycarbonates, and / or bicarbonates of coating elements, such as those discussed below. The compounds constituting the coating may be amorphous and / or crystalline. Coating elements included in the coating may include 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 method for forming the coating may be selected from any suitable method that will not adversely affect the physical properties of the positive electrode active material. The method for forming the coating may include, for example, spraying and / or dipping.

[0032] If, for example, nickel (Ni) is included as the positive electrode active material in a ternary lithium transition metal oxide (such as NCA and / or NCM), the capacity density of the all-solid-state battery 10 can be increased to reduce metal dissolution from the positive electrode active material under charge conditions. Therefore, the all-solid-state battery 10 can improve its cycle characteristics under charge conditions. The term "cycle characteristics" can refer to a characteristic that indicates the degree of degradation of the all-solid-state battery 10 due to charging and discharging. For example, an all-solid-state battery 10 with high cycle characteristics may degrade less due to charging and discharging, while an all-solid-state battery 10 with low cycle characteristics may degrade more due to charging and discharging.

[0033] The positive electrode active material may have a particle shape, for example, spherical (e.g., substantially spherical) or elliptical (e.g., substantially elliptical). There are no limitations on the particle size and amount of the positive electrode active material.

[0034] The solid electrolyte of the positive electrode active material layer 120 may have a particulate shape. The solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte may include a sulfide-based solid electrolyte with excellent lithium-ion conductivity. The sulfide-based solid electrolyte 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 integers, and "Z" is selected from Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each positive integers, and "M" is selected from P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2).

[0035] Sulfide solid electrolytes may include, for example, those selected from Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x A sulfide-germanium ore type compound (sulfide-germanium ore type solid electrolyte) comprising at least one of the following (where 0 ≤ x ≤ 2). For example, a sulfide solid electrolyte may be a sulfide-germanium ore type compound comprising at least one of Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0036] In other embodiments, the sulfide-based solid electrolyte may include Li 7-a M a PS 6-c X cA sulfide-germanium ore type compound (where 0 ≤ a ≤ 2 and 0 ≤ c ≤ 2). In the above chemical formula, X can be F, Br, Cl, or a combination thereof. M may be sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), 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 combinations thereof.

[0037] The sulfide-germanium ore type solid electrolyte can have a density of about 1.5 g / cc to about 2.0 g / cc. Because the sulfide-germanium ore type solid electrolyte has a density equal to or greater than about 1.5 g / cc, it is possible to reduce the internal impedance (e.g., resistance) of the all-solid-state battery and prevent (or reduce the likelihood, occurrence, or extent) short circuits and penetrations of the solid electrolyte layer caused by lithium dendrite formation. The solid electrolyte can have an elastic modulus, for example, from about 15 GPa to about 35 GPa.

[0038] The solid electrolyte in the positive electrode active material layer 120 may have an average particle size smaller than the average particle size of the first and second electrolytes in the solid electrolyte layer 300, which will be discussed further below. For example, the average particle size of the solid electrolyte in the positive electrode active material layer 120 may be approximately equal to or less than approximately 90%, approximately 80%, approximately 70%, approximately 60%, approximately 50%, approximately 40%, approximately 30%, or approximately 20% of the average particle size of the solid electrolyte included in the solid electrolyte layer 300. The average particle size may be the median diameter measured using a laser-type particle size distribution analyzer.

[0039] The positive electrode active material layer 120 may include a conductive material (e.g., an electrically conductive material). The conductive material may be conductive without causing chemical changes (e.g., undesirable chemical changes) in the all-solid-state battery 10, thereby increasing the conductivity (e.g., electronic conductivity) of the positive electrode active material and the solid electrolyte. The conductive material may include carbon-based materials. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers (CNFs), and carbon nanotubes.

[0040] The positive electrode active material layer 120 may further include an adhesive. The adhesive can bond the positive electrode active material, solid electrolyte, and conductive material in the positive electrode active material layer 120 to each other. The adhesive may include materials that improve the adhesion between the positive electrode active material layer 120 and the positive electrode current collector 110. The adhesive may include, for example, polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polyethylene, and / or polymethyl methacrylate.

[0041] Based on a total of 100 parts by weight of the positive electrode active material, solid electrolyte, conductive material, and binder, the positive electrode active material may be included in the positive electrode active material layer 120 in an amount of about 84 parts by weight to about 92 parts by weight. Based on a total of 100 parts by weight of the positive electrode active material, solid electrolyte, conductive material, and binder, the binder may be included in the positive electrode active material layer 120 in an amount of about 0.5 parts by weight to about 1.5 parts by weight.

[0042] Based on 100 parts by weight of solid electrolyte, conductive material can be included in the positive electrode active material layer 120 in an amount of about 1 part by weight to about 50 parts by weight. If, for example, the conductive material is included in an amount less than about 1 part by weight relative to 100 parts by weight of solid electrolyte, the proportion of conductive material may be excessively reduced, thereby reducing the conductivity of the positive electrode active material layer 120. If, for example, the conductive material is included in an amount greater than about 50 parts by weight relative to 100 parts by weight of solid electrolyte, the proportion of conductive material may be excessively increased, resulting in incomplete formation of the coating covering the surface of the solid electrolyte.

[0043] In addition to the positive electrode active material, solid electrolyte, conductive material and binder, the positive electrode active material layer 120 may further include additives such as fillers, coating agents, dispersants and / or ionic conductive agents.

[0044] The negative electrode layer 200 may include a negative electrode current collector 210, a negative electrode coating 220 on the negative electrode current collector 210, and a lithium deposition layer 230, which will be described later.

[0045] The negative electrode current collector 210 may provide a reference surface on which the negative electrode coating 220 is applied. The negative electrode current collector 210 may comprise a material that does not react with lithium (e.g., a material that does not form alloys or compounds with lithium). For example, the negative electrode current collector 210 may comprise at least one material selected from copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector 210 may range from about 1 μm to about 20 μm (e.g., about 5 μm to about 15 μm or about 7 μm to about 10 μm).

[0046] The negative electrode current collector 210 may be formed from one of the metals mentioned above, an alloy of two or more of the metals mentioned above, or a coating material. The negative electrode current collector 210 may have, for example, a plate or foil shape. In some embodiments, the negative electrode current collector 210 may not be provided.

[0047] In an embodiment, a carbon layer may be further included to increase the adhesion between the negative electrode coating 220 and the solid electrolyte layer 300.

[0048] A solid electrolyte layer 300 may be provided between the positive electrode layer 100 and the negative electrode layer 200. The solid electrolyte layer 300 may include 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 the material of the solid electrolyte included in the positive electrode active material layer 120. Solvents (such as isobutyryl isobutyrate) may be used when forming the solid electrolyte layer 300.

[0049] The solid electrolyte layer 300 may include a first solid electrolyte layer 310 and a second solid electrolyte layer 320. The first solid electrolyte layer 310 may be adjacent to the positive electrode layer 100, and the second solid electrolyte layer 320 may be adjacent to the negative electrode layer 200.

[0050] refer to Figure 2 The first solid electrolyte layer 310 may include a first solid electrolyte. The first solid electrolyte may have a spherical or ellipsoidal (e.g., substantially spherical or substantially ellipsoidal) particle shape. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be amorphous, crystalline, or a mixture of amorphous and crystalline states. The solid electrolyte may include at least sulfur (S), phosphorus (P), and lithium (Li) among the constituent elements included in the aforementioned sulfide-based solid electrolytes. For example, the solid electrolyte may be a material comprising Li₂S-P₂S₅. If, for example, Li₂S-P₂S₅ is used as the sulfide-based solid electrolyte material of the solid electrolyte, the molar ratio of Li₂S to P₂S₅ may be in the range of about 50:50 to about 90:10.

[0051] For example, the first solid electrolyte may include: including, for example, those selected from Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7- x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I xThe first solid electrolyte may include at least one of the following: silver-germanium sulfide compounds selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0052] In other embodiments, the first solid electrolyte may include: Li 7-a M a PS 6-c X c These are sulfide-germanium ore-type compounds. In the above chemical formulas, X can be Cl, Br, or a combination thereof. M can be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. Subscripts a and c can each be real numbers greater than or equal to 0 and less than or equal to 2.

[0053] The sulfide-germanium ore type solid electrolyte can have a density of about 1.5 g / cc to about 2.0 g / cc. Since the sulfide-germanium ore type solid electrolyte has a density equal to or greater than about 1.5 g / cc, it is possible to reduce the internal impedance (e.g., resistance) of the all-solid-state battery and prevent (or reduce the likelihood, occurrence, or extent) short circuits and penetrations of the solid electrolyte layer caused by lithium dendrite formation. The first solid electrolyte can have a modulus, for example, from about 15 GPa to about 35 GPa.

[0054] The first solid electrolyte layer 310 may further include an adhesive. The adhesive included in the first solid electrolyte layer 310 may include, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and / or polyethylene, but this disclosure is not limited thereto. The adhesive of the first solid electrolyte layer 310 may be the same as or different from the adhesive of the positive electrode active material layer 120 or the adhesive of the negative electrode coating 220.

[0055] The second solid electrolyte layer 320 may include a second solid electrolyte. The second solid electrolyte may have a spherical or elliptical (e.g., substantially spherical or substantially elliptical) particle shape.

[0056] The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same as or similar to that of the first solid electrolyte. In one embodiment, the second solid electrolyte may have a composition substantially the same as that of the first solid electrolyte. In another embodiment, the second solid electrolyte may have a composition similar to that of the first solid electrolyte.

[0057] The second solid electrolyte can be in direct contact with the negative electrode coating 220. Therefore, the second solid electrolyte can suppress or reduce the formation of lithium dendrites between the negative electrode coating 220 and the negative electrode current collector 210. The second solid electrolyte can effectively suppress or reduce side reactions of the negative electrode layer 200. Therefore, the all-solid-state battery 10 according to this disclosure can improve the performance of the battery cell.

[0058] The first solid electrolyte layer 310 may have a first thickness TK1, and the second solid electrolyte layer 320 may have a second thickness TK2. The first thickness TK1 and the second thickness TK2 may be the same as or different from each other. In an embodiment, the first thickness TK1 may be greater than the second thickness TK2. For example, the first thickness TK1 may be about 1.1 to about 5 times the second thickness TK2.

[0059] Return to reference Figure 1 and Figure 2 The positive electrode layer 100 and the first solid electrolyte layer 310 can constitute a positive electrode mixed layer CSH. The negative electrode layer 200 and the second solid electrolyte layer 320 can constitute a negative electrode mixed layer ASH. The positive electrode mixed layer CSH can be located on the negative electrode mixed layer ASH.

[0060] The negative electrode hybrid layer ASH and the positive electrode hybrid layer CSH can have different areas. For example, the area of ​​the negative electrode hybrid layer ASH can be larger than the area of ​​the positive electrode hybrid layer CSH. The positive electrode hybrid layer CSH can completely overlap with the negative electrode hybrid layer ASH.

[0061] In embodiments of this disclosure, the first solid electrolyte layer 310 may have an area substantially the same as that of the positive electrode layer 100. The second solid electrolyte layer 320 may have an area substantially the same as that of the negative electrode layer 200.

[0062] For example, the positive electrode hybrid layer CSH may have a first width WI1 in the first direction D1. The negative electrode hybrid layer ASH may have a second width WI2 in the first direction D1. The first width WI1 may be smaller than the second width WI2. The positive electrode hybrid layer CSH may have a third width WI3 in the second direction D2. The negative electrode hybrid layer ASH may have a fourth width WI4 in the second direction D2. The third width WI3 may be smaller than the fourth width WI4.

[0063] The all-solid-state battery 10 according to this embodiment can be prepared by forming a negative electrode mixed layer ASH on a first carrier film, forming a positive electrode mixed layer CSH on a second carrier film, and then laminating the negative electrode mixed layer ASH and the positive electrode mixed layer CSH.

[0064] Figure 3 For along Figure 1The cross-sectional view taken along line A-A' shows an all-solid-state battery according to an embodiment of the present disclosure. In the following embodiments, the references to the above will not be repeated here. Figure 1 and Figure 2 The technical features discussed will be described in detail, and their differences will be discussed in more detail.

[0065] refer to Figure 3 The all-solid-state battery 10 may include a spacer GSK. The spacer GSK may be provided around (e.g., surrounding) the positive electrode hybrid layer CSH. The difference in area between the negative electrode hybrid layer ASH and the positive electrode hybrid layer CSH may cause a step difference to be created on the side surface of the all-solid-state battery 10, and the spacer GSK may fill the step difference. The spacer GSK may be around (e.g., surrounding) the four side surfaces of the positive electrode hybrid layer CSH. For example, the thickness of the spacer GSK may be substantially the same as the thickness of the positive electrode hybrid layer CSH.

[0066] The top surface of the second solid electrolyte layer 320 may include a first region in contact with the first solid electrolyte layer 310 and a second region in contact with the gasket GSK. The second region may be a peripheral region of the top surface of the second solid electrolyte layer 320. The second region may surround the first region.

[0067] Figure 4 A cross-sectional view of a negative electrode for an all-solid-state battery according to an embodiment of the present disclosure is shown. Figure 5A and Figure 5B To show as Figure 4 The graph depicts electronic conductivity and ionic conductivity as a function of distance. Figure 6 A cross-sectional view of a negative electrode for an all-solid-state battery according to an embodiment of the present disclosure is shown. Reference will be made to... Figure 4 , Figure 5A , Figure 5B and Figure 6 The negative electrode coating 220 will be discussed in more detail.

[0068] If (for example, when) the all-solid-state battery 10 is charged, lithium metal can grow between the negative electrode coating 220 and the negative electrode current collector 210. The negative electrode coating 220 can serve as a protective layer for the lithium metal and simultaneously (e.g., concurrently) suppress or reduce the precipitation and growth of lithium dendrites.

[0069] The negative electrode coating 220 may include a first negative electrode coating 221 and a second negative electrode coating 222 on the first negative electrode coating 221. The negative electrode layer 200 may include a negative electrode current collector 210, a first negative electrode coating 221 on the negative electrode current collector 210, and a second negative electrode coating 222 on the first negative electrode coating 221. The first negative electrode coating 221 may be located between the negative electrode current collector 210 and the second negative electrode coating 222. The first negative electrode coating 221 and the second negative electrode coating 222 may include materials different from each other (e.g., the first negative electrode coating 221 may include a material different from the material of the second negative electrode coating 222).

[0070] The first negative electrode coating 221 may include a first metal and a first carbon. The first metal may be a lithiophilic element. A lithiophilic element may refer to a metal that exhibits a high affinity for (e.g., for) lithium. For example, the first metal may include at least one lithiophilic element selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), magnesium (Mg), and indium (In). The first negative electrode coating 221 may include a metal oxide containing the first metal.

[0071] The first metal may have a lithium diffusion coefficient that is smaller than that of the second metal, which will be discussed further below. The lithium diffusion coefficient of the first metal may be approximately 10. -14 cm 2 / s ~ approximately 10 -8 cm 2 The range is within / s, but this disclosure is not limited thereto. Since the first negative electrode coating 221 includes a lithium-philic element, the first negative electrode coating 221 may have a lithium-ion conductivity greater than that of the second negative electrode coating 222.

[0072] ΔG1 can represent the Gibbs free energy between molten lithium and the first metal of the first negative electrode coating 221. The Gibbs free energy ΔG1 between the first metal and molten lithium can be defined by the Gibbs free energy expressed by Equation 1.

[0073] Equation 1

[0074] ΔG1=ΔH1 523.15K -TΔS1 523.15K

[0075] For example, ΔG1 can be defined as the Gibbs free energy of the chemical reaction between the first metal and molten lithium at 250°C.

[0076] For example, ΔG1 ≤ 0 kJ / mol. Another example is -1,500 kJ / mol < ΔG1 ≤ 0 kJ / mol. If ΔG1 falls within the above range, an alloying reaction (Li-first metal alloy) can occur between lithium and the first metal. Therefore, if the all-solid-state battery 10 is charged, the first metal can induce lithium deposition. For example, the charge-discharge temperature of the all-solid-state battery 10 can be in the range of about 25°C to about 90°C.

[0077] The first carbon may include at least one selected from carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, and graphene. In an embodiment, the first negative electrode coating 221 may include a mixture of carbon black and silver (Ag).

[0078] In addition to the first metal and the first carbon, the first negative electrode coating 221 may further include additives. The first negative electrode coating 221 may include at least one additive selected from, for example, binders, fillers, coating agents, dispersants and ionic conductive agents.

[0079] The second negative electrode coating 222 may include a second metal and a second carbon. The second metal may be a conductive element (e.g., an electrically conductive element). For example, the second metal may include at least one conductive element selected from beryllium (Be), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), and osmium (Os). The second negative electrode coating 222 may include a metal oxide containing the second metal.

[0080] The second metal can have an electronic conductivity greater than that of the first metal. At a temperature of approximately 20°C, the electronic conductivity of the second metal can be approximately 1 × 10⁻⁶. 6 S / m ~ approximately 1×10 8 S / m, but this disclosure is not limited thereto. Therefore, the second negative electrode coating 222 can facilitate electron transport. Since the second negative electrode coating 222 includes a conductive element (e.g., an electrically conductive element), the second negative electrode coating 222 can have an electronic conductivity greater than that of the first negative electrode coating 221.

[0081] ΔG2 can represent the Gibbs free energy between molten lithium and the second metal of the second negative electrode coating 222. The Gibbs free energy ΔG2 between the second metal and molten lithium can be defined by the Gibbs free energy expressed by Equation 2.

[0082] Equation 2

[0083] ΔG2=ΔH2 523.15K–TΔS2 523.15K

[0084] For example, ΔG2 can be defined as the Gibbs free energy of the chemical reaction between the second metal and molten lithium at 250°C.

[0085] The second metal can be a lithium-phobic element. ΔG2 can be greater than ΔG1. For example, ΔG2 > 0 kJ / mol. Another example is 0 kJ / mol < ΔG2 < 1,000 kJ / mol. If (for example, when) ΔG2 falls within the above range, an alloying reaction may not occur between lithium and the second metal.

[0086] The second carbon may include at least one selected from carbon black, carbon nanotubes, acetylene black, furnace black, Ketjen black, and graphene. In an embodiment, the second negative electrode coating 222 may include a mixture of carbon black and nickel (Ni).

[0087] In addition to the second metal and the second carbon, the second negative electrode coating 222 may further include additives. The second negative electrode coating 222 may include at least one additive selected from, for example, binders, fillers, coating agents, dispersants, and ionic conductive agents.

[0088] For example, the amount of the first metal may be less than the amount of the second metal. For example, the amount of the first metal may be about 3 wt% to about 50 wt% relative to the total weight of the first negative electrode coating 221. For example, the amount of the second metal may be about 5 wt% to about 90 wt% relative to the total weight of the second negative electrode coating 222.

[0089] The first negative electrode coating 221 may have a thickness TH3 of about 3 μm to about 8 μm. The second negative electrode coating 222 may have a thickness TH4 of about 3 μm to about 8 μm. The sum of the thickness TH3 of the first negative electrode coating 221 and the thickness TH4 of the second negative electrode coating 222 may be in the range of about 5 μm to about 20 μm. For example, the sum of the thickness TH3 of the first negative electrode coating 221 and the thickness TH4 of the second negative electrode coating 222 may be in the range of about 5 μm to about 15 μm. The ratio of the thickness TH4 of the second negative electrode coating 222 to the thickness TH3 of the first negative electrode coating 221 may be in the range of about 0.6 to about 1.4. For example, the thickness TH3 of the first negative electrode coating 221 may be substantially the same as the thickness TH4 of the second negative electrode coating 222.

[0090] If, for example, each of the thicknesses TH3 of the first negative electrode coating 221 and TH4 of the second negative electrode coating 222 falls within the ranges above, the all-solid-state battery 10 may have an increased lifetime. If, for example, each of the thicknesses TH3 of the first negative electrode coating 221 and TH4 of the second negative electrode coating 222 is less than the lower limit of the ranges above, no lithium can be uniformly deposited, and dendrites can form in the negative electrode layer 200. If, for example, each of the thicknesses TH3 of the first negative electrode coating 221 and TH4 of the second negative electrode coating 222 is greater than the upper limit of the ranges above, the all-solid-state battery 10 may have a reduced energy density.

[0091] The first negative electrode coating 221 and the second negative electrode coating 222 may not be mixed with each other and can be distinguished by scanning electron microscopy (SEM). The capacity ratio of the negative electrode layer 200 to the capacity of the positive electrode layer 100 may be in the range of about 0.1 to about 0.5. This may be because the all-solid-state battery 10 according to this disclosure does not include a negative electrode active material, and the negative electrode layer 200 includes the first negative electrode coating 221 and the second negative electrode coating 222.

[0092] refer to Figure 5A and Figure 5B Since the first negative electrode coating 221 includes a lithiophilic element, and since the second negative electrode coating 222 includes a conductive element (e.g., an electrically conductive element), the difference in lithium-ion conductivity between the first negative electrode coating 221 and the second negative electrode coating 222 can be reduced. For example, as discussed below, the lithium-ion conductivity of Embodiment 1 of this disclosure can remain constant as a first ion conductivity L1 within a distance X. In contrast, as discussed below, the lithium-ion conductivity of Comparative Example 2 can vary as a function of distance X within a range between a second ion conductivity L2 and a third ion conductivity L3. The lithium-ion conductivity of Comparative Example 2 can increase towards the negative electrode coating 220.

[0093] In this embodiment, the lithium-ion conductivity of Embodiment 1 can vary as a function of distance X within a range between a minimum ionic conductivity L1a and a maximum ionic conductivity L1b. In this embodiment, the first negative electrode coating 221 can have a maximum ionic conductivity L1b, and the second negative electrode coating 222 can have a minimum ionic conductivity L1a. The lithium-ion conductivity can change abruptly at the interface between the first negative electrode coating 221 and the second negative electrode coating 222.

[0094] The difference in electronic conductivity between the first negative electrode coating 221 and the second negative electrode coating 222 can be reduced. For example, the electronic conductivity of Embodiment 1 of this disclosure can remain constant as a first electronic conductivity E1 within a distance X. In contrast, the electronic conductivity of Comparative Example 2 can vary as a function of distance X within a range between a second electronic conductivity E2 and a third electronic conductivity E3. The electronic conductivity of Comparative Example 2 can increase in the direction away from the negative electrode coating 220.

[0095] In this embodiment, as discussed below, the lithium-ion conductivity of Embodiment 1 can vary as a function of distance X within a range between a minimum electronic conductivity E1a and a maximum electronic conductivity E1b. In this embodiment, the first negative electrode coating 221 may have a minimum electronic conductivity E1a, and the second negative electrode coating 222 may have a maximum electronic conductivity E1b. The electronic conductivity may change abruptly at the interface between the first negative electrode coating 221 and the second negative electrode coating 222.

[0096] refer to Figure 6 The negative electrode layer 200 may further include a lithium deposition layer 230. The lithium deposition layer 230 may be located between the negative electrode current collector 210 and the first negative electrode coating 221. The lithium deposition layer 230 may include lithium deposited if (e.g., when) the all-solid-state battery 10 is charged. If (e.g., when) the all-solid-state battery 10 is charged, the lithium deposition layer 230 may be thinly formed on the negative electrode current collector 210.

[0097] For example, a first negative electrode coating 221 and a second negative electrode coating 222 may be sequentially formed on the negative electrode current collector 210. The first negative electrode coating 221 may be formed by coating the negative electrode current collector 210 with a first coating paste comprising the first metal and the first carbon discussed above. For example, the first negative electrode coating 221 may be formed by coating the negative electrode current collector 210 with a first coating paste rod comprising the first metal and the first carbon discussed above.

[0098] The second negative electrode coating 222 can be formed by coating the first negative electrode coating 221 with a second coating paste comprising the second metal and the second carbon discussed above. In an embodiment, the second coating paste may not be mixed with the first negative electrode coating 221. For example, the second negative electrode coating 222 can be formed by coating the first negative electrode coating 221 with a rod of the second coating paste comprising the second metal and the second carbon discussed above.

[0099] According to embodiments of this disclosure, a first negative electrode coating 221 and a second negative electrode coating 222 may be sequentially formed on the negative electrode current collector 210. Since the first negative electrode coating 221 comprises a lithiophilic element, and since the second negative electrode coating 222 comprises a conductive element (e.g., an electrically conductive element), the difference in lithium-ion conductivity and electronic conductivity along the thickness direction (or third direction D3) of the negative electrode layer 200 can be reduced. Therefore, lithium can be uniformly (e.g., substantially uniformly) deposited between the negative electrode current collector 210 and the first negative electrode coating 221, resulting in improved lifetime characteristics of the all-solid-state battery 10.

[0100] The present disclosure will now be discussed in more detail by way of embodiments. However, these embodiments are provided as examples to illustrate the subject matter of the disclosure, and the scope of the disclosure is not limited to these embodiments.

[0101] Implementation Method 1

[0102] A first negative electrode coating 221 and a second negative electrode coating 222 are provided on the negative electrode current collector 210 to form a negative electrode layer 200. The first negative electrode coating 221 comprises silver (Ag) as a first metal, and the amount of silver (Ag) is 15 wt% relative to the total weight of the first negative electrode coating 221. The thickness of the first negative electrode coating 221 is 5 μm. The second negative electrode coating 222 comprises iron (Fe) as a second metal, and the amount of iron is 32 wt% relative to the total weight of the second negative electrode coating 222. The thickness of the second negative electrode coating 222 is 5 μm. ΔG1 represents the Gibbs free energy between silver (Ag) as the first metal and molten lithium, and ΔG2 represents the Gibbs free energy between iron (Fe) as the second metal and molten lithium. In this embodiment, ΔG < ΔG2.

[0103] The negative electrode layer 200 was prepared using the following method.

[0104] A 10 μm thick nickel film was prepared as the negative electrode current collector 210. To form the first negative electrode coating 221, first metal particles, first carbon (carbon black), polyvinylidene fluoride (PVDF) binder (commercially available S5130 from Solvay Co.), and N-methylpyrrolidone (NMP) solvent were mixed to prepare a first coating slurry. The first coating slurry was applied to the nickel film using a doctor blade coater, and the nickel film coated with the first coating slurry was dried in a convection oven at 80°C for 10 minutes to form a stack of the negative electrode current collector 210 and the first negative electrode coating 221. The amount of first carbon was 10 wt% and the amount of PVDF was 8 wt% relative to the total weight of the first negative electrode coating 221.

[0105] To form the second negative electrode coating 222, second metal particles, second carbon (carbon black), polyvinylidene fluoride (PVDF, S5130) binder, and N-methylpyrrolidone (NMP) solvent are mixed to prepare a second coating slurry. The second coating slurry is applied onto the first negative electrode coating 221 using a doctor blade coater, and the mixture is then dried in a convection oven at 80°C for 10 minutes to form a stack of the negative electrode current collector 210, the first negative electrode coating 221, and the second negative electrode coating 222. Through the above process, a negative electrode layer 200 is prepared in which the negative electrode current collector 210, the first negative electrode coating 221, and the second negative electrode coating 222 are sequentially stacked.

[0106] Implementation Method 2

[0107] The negative electrode layer 200 is prepared according to a method substantially the same as that in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) as a first metal in an amount of 5 wt% relative to the total weight of the first negative electrode coating 221, and the thickness of the first negative electrode coating 221 is 7 μm; the second negative electrode coating 222 includes iron (Fe) as a second metal in an amount of 55 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 5 μm.

[0108] Implementation Method 3

[0109] The negative electrode layer 200 is prepared according to a method substantially the same as that in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) as a first metal in an amount of 25 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 5 μm, and the second negative electrode coating 222 includes copper (Cu) as a second metal in an amount of 64 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 6 μm.

[0110] Implementation Method 4

[0111] The negative electrode layer 200 is prepared according to a method substantially the same as that in Embodiment 1, except that the first negative electrode coating 221 includes zinc (Zn) as a first metal in an amount of 40 wt% relative to the total weight of the first negative electrode coating 221, and the thickness of the first negative electrode coating 221 is 7 μm; the second negative electrode coating 222 includes iron (Fe) as a second metal in an amount of 62 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 6 μm.

[0112] Implementation Method 5

[0113] The negative electrode layer 200 is prepared according to a method substantially the same as that in Embodiment 1, except that the first negative electrode coating 221 includes zinc oxide (ZnO) as a metal oxide containing a first metal, having an amount of 30 wt% relative to the total weight of the first negative electrode coating 221, and the thickness of the first negative electrode coating 221 is 6 μm; the second negative electrode coating 222 includes iron (Fe) as a second metal, having an amount of 70 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 4 μm.

[0114] Implementation Method 6

[0115] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) as a first metal in an amount of 44 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 8 μm, and the second negative electrode coating 222 includes nickel (Ni) as a second metal in an amount of 53 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 5 μm.

[0116] Implementation Method 7

[0117] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes zinc (Zn) as a first metal in an amount of 49 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 5 μm, and the second negative electrode coating 222 includes iron (Fe) as a second metal in an amount of 77 wt% relative to the total weight of the second negative electrode coating 222, the thickness of the second negative electrode coating 222 is 3 μm.

[0118] Comparative Example 1

[0119] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that neither the first negative electrode coating 221 nor the second negative electrode coating 222 is formed.

[0120] Comparative Example 2

[0121] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) having an amount of 25 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 10 μm, and the second negative electrode coating 222 is not formed.

[0122] Comparative Example 3

[0123] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 does not include the first metal, the thickness of the first negative electrode coating 221 is 15 μm, the amount of iron (Fe) in the second negative electrode coating 222 is 50 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 15 μm.

[0124] Comparative Example 4

[0125] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) having an amount of 10 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 10 μm, the amount of iron (Fe) in the second negative electrode coating 222 is 32 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 20 μm.

[0126] Comparative Example 5

[0127] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) in an amount of 10 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 18 μm, the amount of iron (Fe) in the second negative electrode coating 222 is 50 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 5.4 μm.

[0128] Comparative Example 6

[0129] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes zinc (Zn) as a first metal having an amount of 40 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 7 μm, the amount of iron (Fe) in the second negative electrode coating 222 is 62 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 15 μm.

[0130] Comparative Example 7

[0131] The negative electrode layer 200 is prepared according to essentially the same method as in Embodiment 1, except that the first negative electrode coating 221 includes silver (Ag) having an amount of 15 wt% relative to the total weight of the first negative electrode coating 221, the thickness of the first negative electrode coating 221 is 3 μm, the amount of iron (Fe) in the second negative electrode coating 222 is 32 wt% relative to the total weight of the second negative electrode coating 222, and the thickness of the second negative electrode coating 222 is 12 μm.

[0132] Table 1 shows a comparison between the negative electrode layers according to the embodiments and comparative examples.

[0133] Table 1

[0134]

[0135] Preparation example: All-solid-state battery

[0136] Positive electrode active material

[0137] Preparation of LiNi 0.8 Co 0.15 Mn 0.05 O2(NCM) powder is used as the active material for the positive electrode.

[0138] Positive electrode layer

[0139] As discussed above, the preparation of LiNi 0.8 Co 0.15 Mn 0.05 O2 (NCM) powder was used as the positive electrode active material. A crystalline silver-germanium sulfide type solid electrolyte (Li6PS5Cl) was prepared as the solid electrolyte. Polytetrafluoroethylene (PTFE, commercially available from DuPont Inc.) was used. TM A binder was used as the binder. Carbon nanofibers (CNFs) were prepared as conductive materials. The positive electrode active material, solid electrolyte, conductive material, and binder were mixed in a weight ratio of 84.2:11.5:2.9:1.4, and the mixture was formed into a positive electrode sheet. The positive electrode sheet was pressed onto a positive electrode current collector formed from a carbon-coated aluminum foil with a thickness of 18 μm to prepare a positive electrode layer. The positive electrode active material layer included in the positive electrode layer had a thickness of approximately 100 μm.

[0140] negative electrode layer

[0141] The aforementioned negative electrode is prepared as the negative electrode layer.

[0142] solid electrolyte layer

[0143] A solid electrolyte solution was prepared by adding the silver sulfide germanite-type solid electrolyte Li6PS5Cl to an isobutyryl isobutyrate binder solution containing acrylate polymers (solid content: 50 wt%, mixing ratio of solid electrolyte to binder: 98.7:1.3).

[0144] A solid electrolyte solution was coated onto a release polytetrafluoroethylene membrane and dried at 60°C for 2 hours to prepare a solid electrolyte layer with a thickness of 100 μm.

[0145] Fabrication of all-solid-state batteries

[0146] The negative electrode layer, solid electrolyte layer, and positive electrode layer were stacked sequentially. The prepared stack was then subjected to plate pressing at 25°C and 100 MPa for 10 minutes to prepare an all-solid-state battery.

[0147] Experimental Example 1: Lifespan of All-Solid-State Batteries

[0148] Lifetime assessments were performed on all-solid-state batteries prepared using the negative electrode layers of Embodiments 1 to 7 and Comparative Examples 1 to 7. For initial charge / discharge, the all-solid-state batteries were initially charged at 25°C under constant current and constant voltage (approximately 4.2V, cutoff approximately 0.01C) at 0.05C, and after a 10-minute rest, discharged to 2.5V at a constant current of 0.05C, thereby obtaining the initial discharge capacity. Lifetime assessments were performed by repeating 100 charge-discharge cycles at a constant current of 0.33C. For example, lifetime assessments were repeatedly performed as follows: the all-solid-state battery was charged at a constant current of 0.33C until the voltage reached 4.25V, charged at a constant voltage (CV) of 4.25V until the current reached 0.1C, and then discharged at a current of 0.33C until the voltage reached 2.5V. Lifetime (charge-discharge efficiency) was calculated according to Equation 3. Based on the calculation results, the lifetime characteristics were assessed as A, B, and C. The lifetime assessment results are listed in Table 2.

[0149] Equation 3

[0150] Lifetime = (Discharge capacity at 100th discharge / Initial discharge capacity) × 100%

[0151] A: Lifespan equal to or greater than 85%

[0152] B: Lifespan equal to or greater than 75% and less than 85%

[0153] C: Lifespan less than 75%

[0154] Table 2

[0155]

[0156]

[0157] Referring to Table 2, the lifespan characteristics of the all-solid-state batteries according to Embodiments 1 to 7 are superior to those of the all-solid-state batteries according to Comparative Examples 1 to 7. Therefore, it can be determined that the lifespan of the all-solid-state battery can be extended depending on the thickness of the first negative electrode coating 221 and the thickness of the second negative electrode coating 222.

[0158] For example, if the negative electrode coating 220 is omitted, or if the first negative electrode coating 221 is formed alone without forming the second negative electrode coating 222, the all-solid-state battery exhibits reduced lifetime characteristics compared to the all-solid-state batteries according to Embodiments 1 to 7.

[0159] Referring to Embodiments 1 to 7 and Comparative Examples 4 to 7, it can be observed that if (for example, when) the thickness of each of the first negative electrode coating 221 and the second negative electrode coating 222 falls within the range of 3 μm to 8 μm, the lifespan of the all-solid-state battery can be extended. It can be determined that if (for example, when) the ratio of the thickness of the second negative electrode coating 222 to the thickness of the first negative electrode coating 221 falls within the range of 0.6 to 1.4, the lifespan characteristics of the all-solid-state battery can be improved.

[0160] According to embodiments of the present disclosure, a first negative electrode coating and a second negative electrode coating may be sequentially formed (e.g., on) a negative electrode current collector. Since the first negative electrode coating comprises a lithiophilic element, and since the second negative electrode coating comprises a conductive element (e.g., an electrically conductive element), it is possible to reduce the difference in lithium-ion conductivity and electronic conductivity along the thickness direction of the negative electrode layers. Therefore, lithium can be uniformly (e.g., substantially uniformly) deposited between the negative electrode current collector and the first negative electrode coating, resulting in improved lifetime characteristics of the all-solid-state battery. All-solid-state batteries according to embodiments of the present disclosure can exhibit superior lifetime characteristics.

[0161] Although some embodiments of this disclosure have been discussed with reference to the accompanying drawings, it will be understood that various suitable changes in form and detail may be made therein without departing from the spirit and scope of this disclosure. Therefore, it will be understood that the above embodiments are merely illustrative and not restrictive in any way.

Claims

1. A negative electrode for an all-solid-state battery, the negative electrode comprising: Negative electrode current collector; A first negative electrode coating is applied to the negative electrode current collector, wherein the first negative electrode coating comprises a first metal and a first carbon. as well as A second negative electrode coating is applied over the first negative electrode coating, wherein the second negative electrode coating comprises a second metal and a second carbon. Where ΔG1 represents the Gibbs free energy of the chemical reaction between the first metal and molten lithium at 250°C. Where ΔG2 represents the Gibbs free energy of the chemical reaction between the second metal and molten lithium at 250°C. Where ΔG1 < ΔG2, and The ratio of the thickness of the second negative electrode coating to the thickness of the first negative electrode coating is in the range of 0.6 to 1.

4.

2. The negative electrode according to claim 1, wherein: ΔG1≤0kJ / mol, and ΔG2>0kJ / mol.

3. The negative electrode according to claim 1, wherein: -1,500 kJ / mol < ΔG1 ≤ 0 kJ / mol, and 0 kJ / mol < ΔG2 < 1,000 kJ / mol.

4. The negative electrode according to claim 1, wherein: The thickness of the first negative electrode coating is in the range of 3 μm to 8 μm, and The thickness of the second negative electrode coating is in the range of 3 μm to 8 μm.

5. The negative electrode according to claim 1, wherein the sum of the thickness of the first negative electrode coating and the thickness of the second negative electrode coating is in the range of 5 μm to 15 μm.

6. The negative electrode according to claim 1, wherein, At a temperature of 20°C, the electronic conductivity of the second metal is 1×10⁻⁶. 6 S / m~1×10 8 S / m.

7. The negative electrode according to claim 1, wherein the lithium diffusion coefficient of the first metal is less than the lithium diffusion coefficient of the second metal. The lithium diffusion coefficient of the first metal is 10. -14 cm 2 / s~10 -8 cm 2 Within the range of / s.

8. The negative electrode according to claim 1, wherein the first metal comprises at least one lithiophilic element selected from gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, magnesium and indium.

9. The negative electrode according to claim 1, wherein the second metal comprises at least one conductive element selected from beryllium, boron, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, technetium, ruthenium, hafnium, tantalum, tungsten, rhenium, and osmium.

10. The negative electrode according to claim 1, wherein: The amount of the first metal relative to the total weight of the first negative electrode coating is 3 wt% to 50 wt%. The amount of the second metal relative to the total weight of the second negative electrode coating is 5 wt% to 90 wt%, and The amount of the first metal is less than the amount of the second metal.

11. The negative electrode according to claim 1, further comprising a lithium deposition layer between the negative electrode current collector and the first negative electrode coating.

12. The negative electrode according to claim 1, wherein: The first carbon comprises at least one selected from carbon black, carbon nanotubes, acetylene black, Ketjen black, and graphene, and The second carbon includes at least one selected from carbon black, carbon nanotubes, acetylene black, Ketjen black, and graphene.

13. The negative electrode according to claim 1, wherein: The ionic conductivity of the first negative electrode coating is the same as or greater than that of the second negative electrode coating. The electronic conductivity of the second negative electrode coating is the same as or greater than that of the first negative electrode coating.

14. The negative electrode according to claim 1, wherein the electronic conductivity of the second metal is greater than that of the first metal.

15. An all-solid-state battery, comprising: Positive electrode layer; Negative electrode layer; and A solid electrolyte layer is located between the positive electrode layer and the negative electrode layer. The negative electrode layer includes: Negative electrode current collector; A first negative electrode coating is applied to the negative electrode current collector, wherein the first negative electrode coating comprises a first metal and a first carbon; and A second negative electrode coating is applied over the first negative electrode coating, wherein the second negative electrode coating comprises a second metal and a second carbon. The ionic conductivity of the first negative electrode coating is greater than that of the second negative electrode coating, and The electronic conductivity of the second negative electrode coating is greater than that of the first negative electrode coating, and The sum of the thickness of the first negative electrode coating and the thickness of the second negative electrode coating is in the range of 5 μm to 15 μm.

16. The all-solid-state battery according to claim 15, wherein: ΔG1 represents the Gibbs free energy of the chemical reaction between the first metal and molten lithium at 250°C. ΔG2 represents the Gibbs free energy of the chemical reaction between the second metal and molten lithium at 250°C. ΔG1≤0kJ / mol, and ΔG2>0kJ / mol.

17. The all-solid-state battery according to claim 15, wherein: -1,500 kJ / mol < ΔG1 ≤ 0 kJ / mol, and 0 kJ / mol < ΔG2 < 1,000 kJ / mol.

18. The all-solid-state battery according to claim 15, wherein: The amount of the first metal relative to the total weight of the first negative electrode coating is 3 wt% to 50 wt%. The amount of the second metal relative to the total weight of the second negative electrode coating is 5 wt% to 90 wt%, and The amount of the first metal is less than the amount of the second metal.

19. The all-solid-state battery according to claim 15, wherein the ratio of the capacity of the negative electrode layer to the capacity of the positive electrode layer is in the range of 0.1 to 0.

5.

20. An all-solid-state battery, comprising: Positive electrode layer; Negative electrode layer; and A solid electrolyte layer is located between the positive electrode layer and the negative electrode layer. The negative electrode layer thereon is a negative electrode according to any one of claims 1 to 14.

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