Solid electrolyte layer, all-solid-state battery containing the same, and method for manufacturing a solid electrolyte layer

Abstract

The present invention provides a solid electrolyte layer with excellent electrical properties and improved atmospheric stability, as well as an all-solid-state battery containing the same. [Solution] The present invention relates to a solid electrolyte layer, an all-solid-state battery containing the same, and a method for manufacturing a solid electrolyte layer, comprising a sulfide-based solid electrolyte, a binder, and an additive, wherein the additive contains metal acetylacetonate.

Description

[Technical Field]

[0001] This invention relates to a solid electrolyte layer, an all-solid-state battery containing the same, and a method for manufacturing a solid electrolyte layer. [Background technology]

[0002] Recently, there has been active development of batteries with high energy density and safety due to industrial demands. For example, lithium-ion batteries are being put into practical use not only in the fields of information-related equipment and communication equipment, but also in the automotive sector. In the automotive sector, safety is important because it is related to human safety.

[0003] Recently, all-solid-state batteries have been developed that use a solid electrolyte instead of a liquid electrolyte. Because all-solid-state batteries do not use flammable organic solvents, the possibility of fire or explosion in the event of a short circuit is significantly reduced. Therefore, such all-solid-state batteries offer a substantial improvement in safety compared to lithium-ion batteries that use liquid electrolytes. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2011-073963 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The problem that the present invention aims to solve is to provide a solid electrolyte layer having desired or improved electrical properties and improved atmospheric stability, and an all-solid-state battery containing the same.

[0006] Another problem that the present invention aims to solve is to provide a method for manufacturing a solid electrolyte layer having desired or improved electrical properties and improved atmospheric stability. [Means for solving the problem]

[0007] The solid electrolyte layer according to an embodiment of the present invention comprises a sulfide-based solid electrolyte, a binder, and an additive, the additive of which may include metal acetylacetonate.

[0008] An all-solid-state battery according to an embodiment of the present invention includes a solid electrolyte layer, a positive electrode, and a negative electrode, wherein the solid electrolyte layer can be positioned between the positive electrode and the negative electrode.

[0009] A method for producing a solid electrolyte layer according to an embodiment of the present invention comprises mixing a sulfide-based solid electrolyte, a binder, an additive, and a solvent to form a solid electrolyte slurry, coating the solid electrolyte slurry onto a substrate, and drying the coated solid electrolyte slurry, wherein the additive may include metal acetylacetonate. [Effects of the Invention]

[0010] The solid electrolyte layer according to the present invention can have excellent electrical properties and excellent atmospheric stability. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view of region M in Figure 1, illustrating the solid electrolyte layer 300 according to an embodiment of the present invention. [Figure 3] This is an enlarged cross-sectional view of region M in Figure 1, illustrating a comparative example of the solid electrolyte layer 300 of the present invention. [Figure 4] This is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in a solid electrolyte layer 300 according to a comparative example of the present invention. [Figure 5] This is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the solid electrolyte layer 300 according to an embodiment of the present invention. [Figure 6] This is a plan view of an all-solid-state battery according to an embodiment of the present invention. [Figure 7A] This is a cross-sectional view along the line A-A' in Figure 6. [Figure 7B] This is a cross-sectional view along the line B-B' in Figure 6. [Figure 8] This is a cross-sectional view along the line A-A' in Figure 6, illustrating an all-solid-state battery according to another embodiment of the present invention. [Figure 9] This graph shows the results of measuring the shear viscosity of the solid electrolyte slurry according to Example 1 of the present invention. [Figure 10] This graph shows the results of measuring the shear viscosity of a comparative example solid electrolyte slurry of the present invention. [Figure 11A] This graph shows the XPS analysis results for the solid electrolyte powder and solid electrolyte membrane of Example 1 and the Comparative Example. [Figure 11B] This graph shows the XPS analysis results for the solid electrolyte powder and solid electrolyte membrane of Example 1 and the Comparative Example. [Modes for carrying out the invention]

[0012] To fully understand the structure and effects of the present invention, preferred embodiments will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various forms and modified in many ways. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those with ordinary skill in the art of which the invention pertains.

[0013] In this specification, when a given component is referred to as being on another component, it means that it can be formed directly on the other component or that a third component may be interposed between them. Furthermore, in the drawings, the thickness of components is exaggerated for the sake of efficient illustration of the technical content. Parts indicated by the same reference number throughout the specification refer to the same component.

[0014] The embodiments described herein are explained with reference to cross-sectional and / or plan views, which are ideal illustrative diagrams of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the efficient explanation of the technical content. Therefore, the regions illustrated in the drawings have schematic attributes, and the shapes of the regions illustrated in the drawings are for illustrative purposes only of the specific shape of the region of the element and are not intended to limit the scope of the invention. In the various embodiments herein, terms such as first, second, third, etc., have been used to describe various components, but these components should not be limited by such terms. These terms are used merely to distinguish certain components from others. The embodiments described and illustrated herein also include complementary embodiments.

[0015] The terms used herein are for illustrative purposes only and are not intended to limit the invention. In this specification, singular forms include plural forms unless specifically mentioned in the text. The terms “comprises” and / or “comprising” as used in this specification do not preclude the presence or addition of one or more other components of the configuration of the secondary battery mentioned.

[0016] In this specification, “these combinations” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the constituents.

[0017] In this specification, each of the phrases such as “A or B,” “at least one of A and B,” “at least one of A or B,” “A, B, or C,” “at least one of A, B, and C,” and “at least one of A, B, or C” may include any one of the items listed together with the phrase in which it applies, or any possible combination thereof.

[0018] Unless otherwise defined herein, particle size may refer to average particle size. Furthermore, particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. Average particle size (D50) can be measured by methods widely known to those skilled in the art, such as using a particle size analyzer, or by using a transmission electron microscope or scanning electron microscope. Alternatively, it can be measured using a dynamic light-scattering device, and after data analysis to count the number of particles for each particle size range, the average particle size (D50) can be calculated. Alternatively, it can be measured using the laser diffraction method. When measuring using the laser diffraction method, more specifically, the particles to be measured are dispersed in a dispersion medium, then introduced into a commercially available laser diffraction particle size analyzer (for example, Microtrac MT 3000), and after irradiating with ultrasound at approximately 28 kHz at an output of 60 W, the average particle size (D50) based on the 50% standard of the particle size distribution in the analyzer can be calculated.

[0019] In one embodiment, the average particle size as used herein may mean the diameter measured by arbitrarily selecting about 100 particles from an electron microscope image. Alternatively, the average particle size as used herein may mean the diameter of a particle that can be measured with a particle size analyzer and whose cumulative volume in the particle size distribution is 50% by volume.

[0020] Where the terms “approximately” or “substantially” are used in relation to numerical values ​​in this specification, the numerical values ​​in question are intended to include a tolerance of ±10% of the stated values. If a range is specified, that range includes all values ​​within that range, such as in increments of 0.1%.

[0021] Figure 1 is a cross-sectional view of an all-solid-state battery according to an embodiment of the present invention.

[0022] Referring to Figure 1, the unit cell CEL of the all-solid-state battery according to the present invention includes a positive electrode layer 100, a negative electrode layer 200 facing the positive electrode layer 100, and a solid electrolyte layer 300 disposed between the positive electrode layer 100 and the negative electrode layer 200. However, the all-solid-state battery 10 may further include additional functional layers, such as adhesion-enhancing layers, disposed 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.

[0023] Positive electrode layer 100 The positive electrode layer 100 according to one embodiment of the present invention may include a positive electrode current collector 110 and a positive electrode active material layer 120 disposed on the positive electrode current collector 110.

[0024] The positive electrode current collector 110 can provide a reference surface on which the positive electrode active material layer 120 is placed. The positive electrode current collector 110 may include a plate or foil containing, for example, at least one of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0025] In other embodiments of the present invention, the positive electrode current collector 110 can be omitted. Although not shown, a carbon layer with a thickness of 0.1 μm to 4 μm may be further arranged between the positive electrode current collector 110 and the positive electrode active material layer 120 to enhance the bonding force between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0026] Positive electrode active material layer 120 The positive electrode active material layer 120 according to one embodiment of the present invention may include a positive electrode active material and a solid electrolyte.

[0027] The cathode active material of the cathode active material layer 120 can include a material that can reversibly absorb (absorb) and desorb (desorb) lithium ions. The cathode active material can include a plurality of particles. The cathode active material can include at least one of, for example, 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 manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. The cathode active materials can each be alone or a mixture of two or more kinds.

[0028] The lithium transition metal oxide is, for example, Li a , c , c , b , 1-b-c , c , a , b , 2-α , b , 2-b , 2-c , 1-b-c , α , 1-b-c , b , α , a , c , 4-c 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 Mnb 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 GeO2(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 Mn2GbO4(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-fA compound that is represented by or contains one of the following: Fe2(PO4)3 (0≦f≦2) or LiFePO4. In such a compound, capital letter "A" is at least one of Ni, Co, Mn, or a combination thereof, or contains one; capital letter "B" is at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, or contains one; capital letter "D" is at least one of O, F, S, P, or a combination thereof, or contains one; capital letter "E" is at least one of Co, Mn, or a combination thereof, or contains one; capital letter "F" is F, S, P, or a combination thereof. At least one of these, or including it, where uppercase "G" is at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, or including it; uppercase "Q" is at least one of Ti, Mo, Mn, or a combination thereof, or including it; uppercase "I" is at least one of Cr, V, Fe, Sc, Y, or a combination thereof, or including it; uppercase "J" is at least one of V, Cr, Mn, Co, Ni, Cu, or a combination thereof, or may include it.

[0029] The positive electrode active material may include, for example, lithium salts of transition metal oxides having a layered rock salt type structure among the lithium transition metal oxides mentioned above. "Layered rock salt type structure" refers to, for example, a cubic rock salt type structure. <111> This structure consists of alternating, regular arrangements of oxygen and metal atomic layers in a directional pattern, where each atomic layer forms a two-dimensional plane. The "cubic rock salt type structure" is a type of crystalline structure, specifically a sodium chloride type (NaCl type) structure, where the face-centered cubic lattices (fcc) formed by the cations and anions are offset from each other by approximately half the ridge length of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure include, for example, LiNi x Co y Alz O2(NCA) or LiNi x Co y Mn z It can be or contain a ternary lithium transition metal oxide such as O2(NCM) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). When the positive electrode active material contains a ternary lithium transition metal oxide having a layered rock salt structure, the energy density of the unit cell CCEL can be increased and the thermal stability can be improved.

[0030] The above-mentioned compound contained in the positive electrode active material can be covered by a coating layer (not shown). The positive electrode active material can also be contained as a mixture of the above-mentioned compound and a compound with a coating layer added. On the other hand, the coating layer added to the surface of the positive electrode active material can contain, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compound forming such a coating layer is amorphous or crystalline. The coating elements contained in the coating layer can include at least one of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating layer can contain, for example, Li2O-ZrO2 (LZO), etc. The coating layer formation method is determined within a range that does not adversely affect the physical properties of the positive electrode active material. The coating layer formation method is, for example, spray coating, dipping method, etc.

[0031] When the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, it is possible to increase the capacity density of the unit cell CEL and reduce the metal elution of the positive electrode active material in the charged state. As a result, the cycle characteristics of the unit cell CEL in the charged state are improved. On the other hand, the "cycle characteristics" may be a characteristic indicating the degree to which the unit cell CEL deteriorates due to charge / discharge of the unit cell CEL. For example, a unit cell CEL with high cycle characteristics has a small degree of deterioration of the unit cell CEL due to charge / discharge, and a unit cell CEL with low cycle characteristics may have a large degree of deterioration of the unit cell CEL due to charge / discharge.

[0032] The positive electrode active material may have particle shapes such as spheres or ellipsoids. The particle size and content of the positive electrode active material are not particularly limited.

[0033] 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 having desired or improved lithium ion conductivity characteristics. Examples of sulfide-based solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiX (where X is or contains 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, and Li2S-P2S5-Z. m S n (m and n are positive numbers, uppercase "Z" is at least one of Ge, Zn, or Ga, or contains one of them), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, the uppercase letter "M" is at least one of P, Si, Ge, B, Al, or Gain, or contains one of these), Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), or Li 7-x PS 6-x I x It can contain at least one element within the range (0 ≤ x ≤ 2).

[0034] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), or Li 7-x PS6-x I x An argyrodite-type compound that contains at least one within (0 ≦ x ≦ 2), or may contain this. In particular, the sulfide-based solid electrolyte is an argyrodite-type compound that contains at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I, or may contain this.

[0035] Or, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c An argyrodite-type compound that contains (0 ≦ a ≦ 2, 0 ≦ c ≦ 2), or may contain this. Here, X is at least one of F, Br, Cl, I, or a combination thereof, or may contain this. M is 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 at least one of a combination thereof, or may contain this. The sulfide-based solid electrolyte is, for example, Li 7-x PS 6-x Cl x (0 ≦ x ≦ 2), Li 7-x PS 6-x Br x (0 ≦ x ≦ 2), Li 7-x PS 6-x I x (0 ≦ x ≦ 2), Li 7-y M1 y PS6-z M2 z (0≦y≦2, 0≦z≦2), or at least one of these combinations, including M1 being at least one element from groups 3 through 15 of the periodic table, and M2 being at least one element from group 17 of the periodic table.

[0036] The density of the algyrodite-type solid electrolyte may be in the range of 1.5 g / cc to 2.0 g / cc. Having a density of 1.5 g / cc or higher for the algyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, preventing or inhibiting defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the solid electrolyte may be, for example, in the range of 15 GPa to 35 GPa.

[0037] The solid electrolyte in the positive electrode active material layer 120 may have a smaller average particle size than the average particle size of the first and second solid electrolytes in the solid electrolyte layer 300, which will be described later. For example, the average particle size of the solid electrolyte in the positive electrode active material layer 120 may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte in the solid electrolyte layer 300. On the other hand, the average particle size may be the median diameter measured using a laser particle size analyzer.

[0038] The positive electrode active material layer 120 may contain a conductive material. The conductive material may enhance the conductivity of the positive electrode active material and solid electrolyte without causing undesirable chemical changes in the unit cell CEL. The conductive material may contain carbon-based materials. The conductive material may contain at least one of the following: graphite, carbon black, acetylene black, carbon nanofibers, or carbon nanotubes.

[0039] The positive electrode active material layer 120 may further contain a binder. The binder can bond the positive electrode active material, solid electrolyte, and conductive material together within the positive electrode active material layer 120. The binder may contain a substance to improve the bonding force between the positive electrode active material layer 120 and the positive electrode current collector 110. The binder may include at least one of the following: polyvinylidene fluoride, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate.

[0040] When the total weight of the positive electrode active material, solid electrolyte, conductive material, and binder is 100 parts by weight, the positive electrode active material layer 120 may contain positive electrode active material in the range of 85 parts by weight or more and 92 parts by weight or less. When the total weight of the positive electrode active material, solid electrolyte, conductive material, and binder is 100 parts by weight, the positive electrode active material layer 120 may contain binder in the range of 0.5 parts by weight or more and 1.5 parts by weight or less.

[0041] When based on 100 parts by weight of the solid electrolyte, the positive electrode active material layer 120 may contain conductive material in the range of 1 part by weight to 50 parts by weight. If the conductive material is included in the positive electrode active material layer 120 in an amount of less than 1 part by weight when based on 100 parts by weight of the solid electrolyte, the proportion of conductive material will decrease, which may reduce the electrical conductivity of the positive electrode active material layer 120. If the conductive material is included in the positive electrode active material layer 120 in an amount exceeding 50 parts by weight when based on 100 parts by weight of the solid electrolyte, the proportion of conductive material will be excessively high, which may prevent the coating layer covering the surface of the solid electrolyte from being properly formed.

[0042] In addition to the positive electrode active material, solid electrolyte, conductive material, and binder described above, the positive electrode active material layer 120 may further contain additives such as fillers, coating agents, dispersants, and ion conductivity enhancers.

[0043] Negative electrode layer 200 The negative electrode layer 200 may include a negative electrode current collector 210 and a coating layer 220 on the negative electrode current collector 210. The negative electrode current collector 210 can provide a reference surface on which the coating layer 220 is placed. The negative electrode current collector 210 may include a material that does not react with lithium, i.e., does not form any alloys or compounds with lithium. For example, the negative electrode current collector 210 may include at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or alloys thereof. The thickness of the negative electrode current collector 210 may be in the range of 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0044] The negative electrode current collector 210 may be composed of one of the above-mentioned metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector 210 may have, for example, a plate shape or a foil shape. On the other hand, in one embodiment, the negative electrode current collector 210 may be omitted.

[0045] Coating layer 220 The coating layer 220 can allow lithium metal to grow between the unit cell CEL and the negative electrode current collector 210 during charging. The coating layer 220 acts as a protective layer for the lithium metal and can also reduce or suppress the deposition and growth of lithium dendrites.

[0046] The coating layer 220 may contain metals and carbon. For example, the coating layer 220 may contain at least one metal such as gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer 220 may contain at least one carbon such as carbon black, acetylene black, furnace black, Ketzen black, and graphene. In one embodiment, the coating layer 220 may contain a mixture of carbon black and silver (Ag).

[0047] The coating layer 220 may further contain other additives in addition to metal and carbon. The coating layer 220 may further contain at least one additive such as a binder, filler, coating agent, dispersant, and ion conductivity enhancer.

[0048] The coating layer 220 may be less thick than the positive electrode active material layer 120. The thickness of the coating layer 220 may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 120. The thickness of the coating layer 220 may be, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the coating layer 220 is excessively thin, such as less than about 1 μm, lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210 will cause the coating layer 220 to break down, degrading the cycle characteristics of the all-solid-state battery. If the thickness of the coating layer 220 is excessively increased, such as greater than about 100 μm, the energy density of the all-solid-state battery will decrease, the internal resistance of the all-solid-state battery due to the coating layer 220 will increase, and the cycle characteristics of the cell will deteriorate. On the other hand, although not shown in the diagram, a carbon layer may be further included between the coating layer 220 and the solid electrolyte layer 300 to improve adhesion.

[0049] solid electrolyte layer 300 The solid electrolyte layer 300 can be provided between the positive electrode layer 100 and the negative electrode layer 200.

[0050] FIG. 2 is for explaining the solid electrolyte layer 300 according to an embodiment of the present invention, and is an enlarged cross-sectional view of the M region in FIG. 1. Referring to FIG. 2, the solid electrolyte layer according to an embodiment of the present invention can include a sulfide-based solid electrolyte SSE, a binder BND, and an additive ADT.

[0051] The solid electrolyte SSE in the solid electrolyte layer 300 can be the same as or different from any one of the substances contained in the solid electrolyte in the positive electrode active material layer 120 described above. The solid electrolyte SSE can have a particle shape such as a sphere or an ellipsoid. The solid electrolyte SSE can include a sulfide-based solid electrolyte. The solid electrolyte SSE can be amorphous, crystalline, or a mixed state thereof. Also, the solid electrolyte SSE can contain at least one of sulfur (S), phosphorus (P), and lithium (Li) as at least a constituent element, for example, among the sulfide-based solid electrolyte materials described above. For example, the solid electrolyte SSE can be a material containing Li2S-P2S5 or can contain this. When using a sulfide-based solid electrolyte material forming the solid electrolyte SSE and containing Li2S-P2S5, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5 = 50:50 to 90:10.

[0052] In one embodiment, the solid electrolyte SSE is Li 7-x PS 6-x Cl x (0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (0 ≤ x ≤ 2), or Li 7-x PS 6-x I xThe solid electrolyte SSE may contain, or be an argyrodite-type compound containing at least one of the following: (0 ≤ x ≤ 2).

[0053] In another embodiment, the solid electrolyte SSE is Li 7-a-c M a PS 6-c X c This may include argyrodite-type compounds containing , where X is at least one of Cl, Br, or a combination thereof, or may include these. M is at least one of Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, or may include these. Each of a and c may be a real number between 0 and 2. Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), Li 7-x PS 6-x I x (0≦x≦2), Li 7-y M1 y PS 6-z M2 z (0≦y≦2, 0≦z≦2), or at least one combination thereof, where M1 is at least one element from groups 3 through 15 of the periodic table, or includes such element, and M2 is at least one element from group 17 of the periodic table, or includes such element.

[0054] The density of the algyrodite-type solid electrolyte may be in the range of 1.5 g / cc to 2.0 g / cc. Having a density of 1.5 g / cc or higher for the algyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, preventing or preventing defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the solid electrolyte SSE is, for example, in the range of 15 GPa to 35 GPa.

[0055] The binder BND of the solid electrolyte layer 300 can bind the solid electrolyte SSE particles together. The binder BND can improve the bonding strength between the solid electrolyte layer 300 and the positive electrode 100 or between the solid electrolyte layer 300 and the negative electrode 200, thereby improving the mechanical strength and stability of the solid electrolyte layer 300.

[0056] The binder BND may include at least one of the following: an acrylic binder, a fluorine binder, a rubber binder, or a combination thereof. The binder BND may include at least one of the following: acrylic rubber, acrylonitrile rubber, polyacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polymethyl acrylate, polyacrylic acid, polyvinylidene fluoride, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate. In one embodiment, the binder BND may include an acrylic binder.

[0057] The additive ADT in the solid electrolyte layer 300 can improve the dispersibility of the solid electrolyte SSE and binder BND. Therefore, the additive ADT can improve the electrical properties of the solid electrolyte layer 300.

[0058] The additive ADT may include, for example, a metal acetylacetonate. The central metal of the metal acetylacetonate is not particularly limited as long as it is a metal that can form a complex compound with the acetylacetonate ligand. For example, the central metal of the metal acetylacetonate may include at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), manganese (Mn), zirconium (Zr), tin (Sn), gallium (Ga), zinc (Zn), chromium (Cr), or a combination thereof. In one embodiment, the central metal of the metal acetylacetonate may be an aluminum cation (Al 3+ ) or may include this.

[0059] When the central metal of a metal-acetylacetonate is a divalent cation, two acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and consequently, the metal-acetylacetonate can have a four-coordinate plane square structure.

[0060] When the central metal of a metal-acetylacetonate is a trivalent cation, three acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and consequently, the metal-acetylacetonate can have a hexa-coordinate octahedron structure.

[0061] When the central metal of a metal-acetylacetonate is a tetravalent cation, four acetylacetonates can participate in the coordination bond. Each acetylacetonate ligand forms two coordination bonds through two oxygen atoms, and as a result, the metal-acetylacetonate can have an octahedron with an eight-coordinate biscape (bisphenoid geometry), or a distorted square arrangement, etc.

[0062] Examples of metal-acetylacetonates include, but are not limited to, aluminum(III) acetylacetonate, copper(II) acetylacetonate, manganese(II) acetylacetonate, and manganese(III) acetylacetonate.

[0063] The additive ADT can interact with sulfide-based solid electrolytes (SSE). For example, forces such as Lewis acid-base interactions, ion-ion interactions, or ion-dipole interactions can act between the additive ADT and the sulfide-based solid electrolyte SSE.

[0064] For example, the metal ions of metal acetylacetonate act as Lewis acids, and the sulfur ions (S) of sulfide-based solid electrolytes SSEs 2- ) may act as a Lewis base, and a Lewis acid-base interaction may occur between the additive ADT and the sulfide-based solid electrolyte SSE. Alternatively, the sulfur anion (S) of the sulfide-based solid electrolyte SSE may act as a Lewis base. 2- ) or lithium cation (Li + An ion-ion interaction may occur between the metal ions of the metal acetylacetonate and the metal ions of the metal acetylacetonate. Alternatively, since all metal ions of metal acetylacetonate and acetylacetone ligands are polar, the sulfur anion (S) of the sulfide-based solid electrolyte SSE may interact with the metal ions of the metal acetylacetonate. 2- ) or lithium cation (Li + ) can also exchange ionic dipole interactions.

[0065] The additive ADT can interact with the binder BND. For example, forces such as Lewis acid-base interactions, ion-dipole interactions, and van der Waals forces can act between the additive ADT and the binder BND.

[0066] For example, the metal ions of metal acetylacetonate may act as Lewis acids, and the functional groups contained in the binder BND (e.g., carbonyl groups (C=O), hydroxyl groups (-OH), epoxy groups (-O-), etc.) may act as Lewis bases, resulting in Lewis acid-base interactions between the additive ADT and the binder BND. Alternatively, van der Waals forces may exist between the acetylacetone ligand of the metal acetylacetonate and the nonpolar portion of the binder (e.g., the fluorocarbon chain of PVDF).

[0067] The additive ADT interacts with at least one of the sulfide-based solid electrolytes (SSE) and binders (BND) to reduce or prevent aggregation of the SSE and BND. Suppression of aggregation between the SSE and BND improves the phase stability of the solid electrolyte slurry and enhances the ionic conductivity of the solid electrolyte layer.

[0068] In a solid electrolyte slurry, the solid electrolyte SSE and binder BND will aggregate due to electrostatic attraction, van der Waals forces, and interactions with the solvent. When the solid electrolyte SSE and binder BND aggregate, they cannot be uniformly dispersed in the solvent and can form clusters. These aggregated clusters reduce the contact area with the solvent, decreasing the particle dispersibility within the slurry. The aggregated clusters also make the viscosity and rheological properties of the slurry non-uniform, reducing its flowability and decreasing the phase stability of the slurry.

[0069] As described above, the additive ADT according to embodiments of the present invention can interact with at least one of the sulfide-based solid electrolyte SSE and the binder BND. The additive ADT can be located on the surface of the sulfide-based solid electrolyte SSE to reduce or inhibit aggregation of the binder BND and the solid electrolyte. Alternatively, the additive ADT can be located around the binder BND to reduce or inhibit aggregation of the binder BND and the solid electrolyte. Again, the additive ADT according to embodiments of the present invention can interact with at least one of the sulfide-based solid electrolyte SSE and the binder BND to reduce or inhibit aggregation of the binder BND and the solid electrolyte SSE. Consequently, the additive BND can improve the dispersibility and phase stability of the solid electrolyte slurry, thereby improving the electrical properties of the solid electrolyte layer produced.

[0070] Figure 3 illustrates a solid electrolyte layer 300 according to a comparative example of the present invention and is an enlarged cross-sectional view of region M in Figure 1. Figure 4 is a schematic diagram showing the distribution shape of the solid electrolyte SSE and binder BND in the solid electrolyte layer 300 according to a comparative example of the present invention.

[0071] Referring to Figures 3 and 4, in the comparative example solid electrolyte layer 300, the solid electrolyte SSE and binder BND exist in an aggregated clump state. When the solid electrolyte SSE and binder BND aggregate and the binder BND covers the surface of the solid electrolyte SSE or between the solid electrolyte SSE particles, the lithium ion migration pathway is blocked, and the ionic conductivity of the solid electrolyte layer 300 decreases.

[0072] Figure 5 is a schematic diagram showing the distribution shape of solid electrolyte SSE and binder BND in a solid electrolyte layer 300 according to an embodiment of the present invention. Referring to Figures 2 and 5, in the solid electrolyte layer 300 according to the embodiment, the solid electrolyte SSE and binder BND can exist in a uniformly dispersed form without substantially agglomerating. If the distribution of binder BND around the solid electrolyte SSE is reduced, the interparticle contact area of ​​the solid electrolyte SSE can be increased, thereby improving lithium ion conductivity.

[0073] Since the solid electrolyte slurry and the solid electrolyte layer 300 contain a sulfide-based solid electrolyte SSE that is highly reactive with water (H2O) and carbon dioxide (CO2), they have relatively low atmospheric stability, and the additive ADT can improve the atmospheric stability of the solid electrolyte slurry and the solid electrolyte layer 300.

[0074] When a chemically stable metal acetylacetonate is located around a sulfide-based solid electrolyte (SSE), contact between the SSE and moisture in the air can be limited. Alternatively, the metal acetylacetonate can adsorb water molecules on the surface of the SSE, or its ligand structure can suppress the reaction with moisture, thereby mitigating the moisture reaction of the SSE. Consequently, the metal acetylacetonate can suppress the reaction of the SSE with moisture in the atmosphere, thereby improving the atmospheric stability of the solid electrolyte slurry and the solid electrolyte layer 300.

[0075] The additive ADT protects sulfide-based solid electrolytes (SSEs) from atmospheric moisture through Lewis acid-base interactions, etc., while having little effect on the chemical structure of the sulfide-based solid electrolytes (SSEs). In other words, the additive ADT can improve the atmospheric stability of sulfide-based solid electrolytes (SSEs) without deforming them.

[0076] The additive ADT in the manufactured solid electrolyte layer 300 can be identified by FT-IR spectroscopy (Fourier-Transform Infrared Spectroscopy), TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry), or GC-MS (Gas Chromatography-Mass Spectrometry).

[0077] In one embodiment, a sample taken from the positive electrode active material layer 120 was analyzed by FT-IR to identify a peak characteristic of acetylacetonate ligand (e.g., 1600-1500 cm⁻¹). -1Additive ADT can be detected by confirming the C=O extensional vibration of the region. In another embodiment, the presence of metallic acetylacetonate can be directly or indirectly confirmed by individually detecting metal ions and acetylacetonate ligands from the cathode surface through TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis.

[0078] The content of the additive ADT in the solid electrolyte layer 300 may be in the range of 0.1 to 1.5 parts by weight per 100 parts by weight of the solid electrolyte layer 300. For example, the content of the additive ADT may be 0.1 to 1.2 parts by weight, or 0.1 to 1.0 part by weight.

[0079] If the content of additive ADT in the solid electrolyte layer 300 is too small, for example, less than about 0.1 parts by weight, it will be difficult to improve the dispersibility and atmospheric stability of the solid electrolyte layer 300. If the content of additive ADT in the solid electrolyte layer 300 is too large, for example, greater than about 1.5 parts by weight, the content of solid electrolyte SSE will be relatively reduced, and the ionic conductivity of the solid electrolyte layer 300 will actually decrease. When the content of additive ADT satisfies the range described above, the solid electrolyte layer 300 can have improved atmospheric stability along with improved ionic conductivity.

[0080] The weight ratio of additive ADT to binder BND in the solid electrolyte layer 300 may be in the range of 1:0.01 to 1:0.5. For example, the weight ratio of additive ADT to binder BND may be 1:0.02 to 1:0.3 or 1:0.03 to 1:0.2. If the weight ratio of additive ADT to binder BND satisfies the range described above, the solid electrolyte layer 300 can have the desired or improved ionic conductivity and the desired or improved durability.

[0081] The sulfide-based solid electrolyte SSE in the solid electrolyte layer 300 may be in the range of 90 parts by weight or more per 100 parts by weight of the solid electrolyte layer 300. For example, the content of sulfide-based solid electrolyte SSE may be 90 to 99 parts by weight, 90 to 98 parts by weight, or 90 to 97 parts by weight.

[0082] The solid electrolyte layer 300 may further contain fillers, coating agents, dispersants, ion conductivity enhancers, etc., in addition to the solid electrolyte SSE, binder BND, and additive ADT described above. In one embodiment, the solid electrolyte layer 300 may further contain a dispersant. The dispersant can further improve the dispersibility of the solid electrolyte slurry and reduce the interfacial tension between the solid electrolyte and the solvent, thereby improving the stability of the slurry.

[0083] Method for manufacturing a solid electrolyte layer A method for producing a solid electrolyte layer according to an embodiment of the present invention may include mixing a sulfide-based solid electrolyte, a binder, an additive, and a solvent to form a solid electrolyte slurry, coating the solid electrolyte slurry onto a substrate, and drying the coated solid electrolyte slurry.

[0084] Sulfide-based solid electrolytes, binders, and additives can be mixed under a solvent to form a solid electrolyte slurry. The solvent is a nonpolar organic solvent or a weakly polar organic solvent that has low reactivity with the sulfide-based solid electrolyte, or may include such solvents. For example, the solvent may include at least one of xylene, benzene, toluene, pentane, hexane, cyclic hexane, octyl acetate, nonyl acetate, isobutyl isobutyrate (IBIB), or a combination thereof. In one embodiment, the solvent may include octyl acetate.

[0085] In the aforementioned hybrid method, any method that can be used by an ordinary engineer is possible, and it is not limited to any specific method.

[0086] As an example, the mixing can be carried out using a mixer or kneader. In one embodiment of the present invention, the mixing can be carried out using a PD mixer (Planetary Disperser mixer), a Planetary mixer, a Paddle mixer, a Ribbon mixer, a Dual shaft mixer mixer, a High-speed impeller mixer, or a Propeller mixer.

[0087] The sulfide-based solid electrolyte, binder, and additive may each be the same as those described above.

[0088] For example, sulfide-based solid electrolytes include Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), or Li 7-x PS 6-x I x The solid electrolyte may contain an argyrodite-type compound containing at least one element in (0 ≤ x ≤ 2). The sulfide-based solid electrolyte may be an argyrodite-type compound containing at least one element from Li6PS5Cl, Li6PS5Br, or Li6PS5I, or may contain such a compound.

[0089] In another embodiment, the sulfide-based solid electrolyte is Li 7-a-c M a PS 6-c X cThis may include argyrodite-type compounds containing the following: where X is at least one of F, Cl, Br, or a combination thereof, or may include these; M is at least one of Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, or may include these; each of a and c may be a real number between 0 and 2.

[0090] The additive may include, for example, a metal acetylacetonate, the central metal of which may include at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zinc (Zn), chromium (Cr), or a combination thereof.

[0091] The binder BND may include, for example, at least one of acrylic rubber, acrylonitrile rubber, polyacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polymethyl acrylate, polyacrylic acid, polyvinylidene fluoride, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate.

[0092] The solid electrolyte layer 300 may further contain a coating agent, a dispersant, an ion conductivity enhancer, etc. In one embodiment, the solid electrolyte layer 300 may further contain a dispersant.

[0093] In the manufactured solid electrolyte slurry, the additive can interact with at least one of the sulfide-based solid electrolytes and binders to reduce or inhibit aggregation between the binder and the solid electrolyte. Consequently, the additive can improve the dispersibility and phase stability of the solid electrolyte slurry. The additive can also prevent degradation of the sulfide-based solid electrolyte by limiting contact between the sulfide-based solid electrolyte and moisture in the air and the solvent.

[0094] On the other hand, additives can generally not affect the chemical structure of sulfide-based solid electrolytes. Again, additives can prevent or avoid degradation of sulfide-based solid electrolytes without altering their structure.

[0095] The prepared solid electrolyte slurry can be coated onto a substrate and dried to form a solid electrolyte layer.

[0096] The material used as the base material is not particularly limited and may include, for example, at least one of a porous polymer matrix, a release film, foil, aluminum, and SUS.

[0097] Coating can be carried out using general methods. For example, coating can be performed using a bar coater, blade coater, etc. Any method capable of applying slurry is acceptable for coating, and is not limited to the examples given.

[0098] The drying process can be carried out in a dryer. For example, the dryer may include, but is not limited to, a convection oven, a vacuum oven, etc.

[0099] In the embodiments described later, detailed explanations of technical features that overlap with those previously explained with reference to Figures 1 to 5 will be omitted, and the differences will be explained in detail.

[0100] Figure 6 is a plan view of an all-solid-state battery according to an embodiment of the present invention. Figure 7A is a cross-sectional view taken along the line A-A' in Figure 6. Figure 7B is a cross-sectional view taken along the line B-B' in Figure 6.

[0101] Referring to Figures 6, 7A, and 7B, 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.

[0102] The first solid electrolyte layer 310 may contain the first solid electrolyte. The second solid electrolyte layer 320 may contain the second solid electrolyte. Each of the first and second solid electrolytes may be the same as the sulfide-based solid electrolyte SSE described above with reference to Figure 2. For example, each of the first and second solid electrolytes may have a particle shape such as a sphere or an ellipsoid. The first and second solid electrolytes may be amorphous, crystalline, or a mixture thereof.

[0103] Each of the first solid electrolyte layer 310 and the second solid electrolyte layer 320 may further contain a binder. The binders contained in the first and second solid electrolyte layers 310 and 320 may be at least one of the following, or a combination thereof: acrylic rubber, acrylonitrile rubber, polyacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polymethyl acrylate, polyacrylic acid, polyvinylidene fluoride, styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, or a combination thereof.

[0104] Each of the first solid electrolyte layer 310 and the second solid electrolyte layer 320 may further contain additives. These additives may include, for example, metal acetylacetonates. The central metal of the metal acetylacetonate is not particularly limited, as long as it is a metal capable of forming a complex with an acetylacetonate ligand. For example, the central metal of the metal acetylacetonate may include at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), zinc (Zn), chromium (Cr), or a combination thereof.

[0105] The second solid electrolyte can come into direct contact with the coating layer 220. Therefore, the second solid electrolyte can reduce or suppress lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210. The second solid electrolyte can effectively reduce or suppress negative electrode side reactions. Therefore, the cell performance of the all-solid-state battery according to the present invention can be improved.

[0106] 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 or different. In one embodiment, the first thickness TK1 may be greater than the second thickness TK2. For example, the first thickness TK1 may be 1.1 to 5 times the second thickness TK2.

[0107] Referring again to Figures 6, 7A, and 7B, the positive electrode layer 100 and the first solid electrolyte layer 310 can constitute the positive electrode composite layer CSH. The negative electrode layer 200 and the second solid electrolyte layer 320 can constitute the negative electrode composite layer ASH. The positive electrode composite layer CSH can be laminated on the negative electrode composite layer ASH.

[0108] The areas of the negative electrode composite layer ASH and the positive electrode composite layer CSH may be different from each other. Specifically, the area of ​​the negative electrode composite layer ASH may be larger than the area of ​​the positive electrode composite layer CSH. The positive electrode composite layer CSH can be completely covered within the negative electrode composite layer ASH.

[0109] In one embodiment of the present invention, the first solid electrolyte layer 310 may have substantially the same area as the positive electrode layer 100. The second solid electrolyte layer 320 may have substantially the same area as the negative electrode layer 200.

[0110] Specifically, the positive electrode composite layer CSH may have a first width WI1 in the first direction D1. The negative electrode composite 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 composite layer CSH may have a third width WI3 in the second direction D2. The negative electrode composite 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.

[0111] The unit cell CEL according to this embodiment can be manufactured by forming a negative electrode composite layer ASH on a first carrier film, forming a positive electrode composite layer CSH on a second carrier film, and then laminating the negative electrode composite layer ASH and the positive electrode composite layer CSH.

[0112] The unit cell CEL according to this embodiment may further include a gasket GSK. The gasket GSK may be provided so as to surround the positive electrode composite layer CSH. The gasket GSK can fill the step on the side surface of the unit cell CEL caused by the area difference between the negative electrode composite layer ASH and the positive electrode composite layer CSH. The gasket GSK may surround all four sides of the positive electrode composite layer CSH. As an example, the thickness of the gasket GSK may be substantially the same as or less than the thickness of the positive electrode composite layer CSH. In one embodiment, the positive electrode current collector 110 may be provided at a higher position than the gasket GSK.

[0113] The positive electrode current collector 110 may include a positive electrode tab CTB. The positive electrode tab CTB may be a protruding region of the positive electrode current collector 110. In one embodiment, the positive electrode tab CTB may protrude in a second direction D2.

[0114] The negative electrode current collector 210 may include a negative electrode tab ATB. The negative electrode tab ATB may be a protruding region of the negative electrode current collector 210. In one embodiment, the negative electrode tab ATB may protrude in the direction opposite to the second direction D2.

[0115] Figure 8 illustrates an all-solid-state battery according to another embodiment of the present invention and is a cross-sectional view along the line A-A' in Figure 6. Referring to Figure 8, the negative electrode layer 200 of the unit cell CEL may further include a lithium metal layer 400 between the negative electrode current collector 210 and the coating layer 220. The thickness of the lithium metal layer 400 can be further increased when the unit cell CEL is charged. The coating layer 220 performs a protective role for the lithium metal layer 400 and at the same time can reduce or suppress the growth of lithium dendrites from the lithium metal layer 400.

[0116] The lithium metal layer 400 may be lithium or a lithium alloy, or may contain both. Since the lithium metal layer 400 is a lithium-containing metal layer, it can act, for example, as a lithium reservoir. The lithium alloy may be, but is not limited to, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., or include them, and any lithium alloy used in the art may be used. The lithium metal layer 400 may be made of one of these alloys or lithium, but can be made of various types of alloys. The lithium metal layer 400 may be, for example, a plated layer. The lithium metal layer 400 may be deposited between the coating layer 220 and the negative electrode current collector 210 during the charging process of a unit cell CEL, for example.

[0117] In another embodiment of the present invention, the lithium metal layer 400 within the negative electrode 200 can be provided between the negative electrode current collector 210 and the coating layer 220, for example, before the assembly of the unit cell CEL. When the lithium metal layer 400 is placed between the negative electrode current collector 210 and the coating layer 220 before the assembly of the all-solid-state battery, the lithium metal layer 400 can act as a lithium reservoir, since it is or may contain lithium. For example, a lithium foil may be placed between the negative electrode current collector 210 and the coating layer 220 before the assembly of the unit cell CEL.

[0118] If the lithium metal layer 400 is deposited by charging after the assembly of the unit cell CEL, the energy density of the unit cell CEL will increase because the unit cell CEL does not contain the lithium metal layer during assembly. When the unit cell CEL is charged, the charging will exceed the charging capacity of the coating layer 220. That is, the coating layer 220 will be overcharged. In the initial stages of charging, lithium can be absorbed by the coating layer 220. If the charging exceeds the capacity of the coating layer 220, lithium will be deposited, for example, between the negative electrode coating layer 220 and the negative electrode current collector 210. The deposited lithium will form the metal layer 400.

[0119] The lithium metal layer 400 is mainly composed of lithium (i.e., metallic lithium), or may contain lithium. During discharge, the lithium in the lithium metal layer 400 can be ionized and moved to the positive electrode 100. In other words, lithium can be used as the negative electrode active material in the unit cell CEL. Furthermore, since the coating layer 220 covers the lithium metal layer 400, the coating layer 220 protects the lithium metal layer 400 while simultaneously reducing or suppressing the deposition and growth of lithium dendrites. Therefore, the coating layer 220 can reduce or suppress short circuits and capacity degradation in the unit cell CEL, thereby improving the cycle characteristics of the unit cell CEL.

[0120] If a lithium metal layer 400 is formed by charging after the assembly of the unit cell CEL, the negative electrode 200, i.e., the negative electrode current collector 210 and the coating layer 220 and the region between them, may be a lithium (Li)-free region in the initial state of the unit cell CEL or after complete discharge.

[0121] The lithium metal layer 400 may have a fifth width WI5 in the first direction D1. The fifth width WI5 may be the same as or larger than the first width WI1. The fifth width WI5 may be the same as or smaller than the second width WI2. For example, the fifth width WI5 may be larger than the first width WI1 and smaller than the second width WI2.

[0122] The negative electrode 200 may further include a thin film provided between the negative electrode current collector 210 and the coating layer 220. The thin film is provided on one surface of the negative electrode current collector 210 and can form an alloy with lithium.

[0123] The thin film may contain, for example, an element that can form an alloy with lithium. Elements that can form alloys with lithium include, for example, at least one of gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but are not necessarily limited to these; any element that can form an alloy with lithium in the relevant art is acceptable. The thin film may be composed of one of these metals, or of an alloy of various types of metals, or may contain a combination of these metals.

[0124] By placing the thin film on one surface of the negative electrode current collector 210, the deposition morphology of the lithium metal layer deposited between the thin film and the coating layer 220 can be further flattened, thereby further improving the cycle characteristics of the all-solid-state battery.

[0125] The thickness of the thin film may be, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is less than 1 nm, the function of the thin film may not be easily achieved. If the thickness of the thin film is too thick, for example, greater than 800 nm, the thin film itself may absorb lithium, reducing the amount of lithium deposited on the negative electrode 200, lowering the energy density of the all-solid-state battery, and thus degrading the cycle characteristics of the all-solid-state battery. The thin film can be formed on the negative electrode current collector 210 by, for example, vacuum deposition, sputtering, or plating, but is not limited to these methods; any method capable of forming a thin film in the relevant art is possible.

[0126] The present invention will be described in more detail below through embodiments. However, these embodiments are for illustrative purposes only, and the scope of the present invention is not limited to these embodiments.

[0127] Example 1 (Solid electrolyte slurry manufacturing) Algyrodite-based solid electrolyte (Li6PS5Cl) powder was prepared as a sulfide-based solid electrolyte. A butyl acrylate polymer was prepared as a binder, and polyethylene glycol (PEG) as a dispersant. Aluminum acetylacetonate was prepared as an additive. The solid electrolyte powder, binder, dispersant, and additive were mixed in an octyl acetate solvent to produce a solid electrolyte slurry (the weight ratio of the solid electrolyte, binder, dispersant, and additive was 93.8:5:0.6:0.6).

[0128] (Solid electrolyte layer manufacturing) The manufactured solid electrolyte slurry was applied to a release polytetrafluoroethylene film and dried at 60°C for 2 hours to produce a solid electrolyte membrane.

[0129] Example 2 The solid electrolyte slurry was prepared in the same manner as in Example 1, except that the solid electrolyte, binder, dispersant, and additives were mixed in a weight ratio of 94:5:0.6:0.4.

[0130] Example 3 The solid electrolyte slurry was prepared in the same manner as in Example 1, except that the solid electrolyte, binder, dispersant, and additives were mixed in a weight ratio of 94.2:5:0.6:0.2.

[0131] Example 4 The solid electrolyte slurry was prepared in the same manner as in Example 1, except that the solid electrolyte, binder, dispersant, and additives were mixed in a weight ratio of 93.4:5:0.6:1.

[0132] Example 5 The solid electrolyte slurry was prepared in the same manner as in Example 1, except that the solid electrolyte, binder, dispersant, and additives were mixed in a weight ratio of 93.1:5:0.6:1.3.

[0133] Comparative Example The solid electrolyte slurry was prepared using the same method as in Example 1, except that no additives were added and the solid electrolyte, binder, and dispersant were mixed in a weight ratio of 94.4:5:0.6.

[0134] Evaluation Example 1: Evaluation of Solid Electrolyte Slurry Phase Stability The shear viscosity of the solid electrolyte slurries prepared according to the examples and comparative examples was measured using an Anton Paar Rheometer. After adding 10 ml of the solid electrolyte slurry to the apparatus, the shear viscosity was measured.

[0135] Phase stability was evaluated by measuring the shear viscosity (viscosity at a shear rate of 10¹ / s) of the solid electrolyte slurries of the examples and comparative examples immediately after preparation and at room temperature (20°C) after being left undisturbed for 1 day. The results are shown in Figures 9 and 10, and Table 1 below. The viscosity increase rate was calculated using Equation 1 below. [Formula 1] Viscosity increase rate (%) = [(Shear viscosity after 1 day of standing without stirring - Shear viscosity immediately after manufacturing) / Shear viscosity immediately after manufacturing] x 100

[0136] [Table 1]

[0137] Referring to Figures 9 and 10, and Table 1, it can be confirmed that the solid electrolyte slurry according to the embodiment shows a significantly smaller viscosity change rate after standing without stirring compared to the solid electrolyte slurry according to the comparative example.

[0138] Evaluation Example 2: Evaluation of Ionic Conductivity of Solid Electrolyte Membranes The ionic conductivity of solid electrolyte membranes in the examples and comparative examples was measured. The impedance of the solid electrolyte membrane was measured using a potentiostat (AUTOLAB PGSTAT30 (Metrohm Autolab Co. Ltd.)), and the ionic conductivity at 25°C was determined from the Nyquist plot. The results are shown in Table 2 below.

[0139] [Table 2]

[0140] Referring to Table 2, it can be confirmed that the solid electrolyte membranes according to Examples 1 to 5 have equivalent or even superior ionic conductivity compared to the solid electrolyte membranes according to the comparative examples.

[0141] Evaluation Example 3: Solid Electrolyte Evaluation XPS (X-ray Photoelectron Spectroscopy) analysis was performed on the sulfide-based solid electrolyte (Li6PS5Cl) powder used in the examples and comparative examples, the solid electrolyte membrane of Example 1, and the solid electrolyte membrane of the comparative example, and the results are shown in Figure 11.

[0142] Referring to Figure 11, it can be confirmed that the solid electrolyte contained in the solid electrolyte membrane of Example 1 exhibits even less structural change compared to the solid electrolyte contained in the solid electrolyte membrane of the comparative example.

[0143] The solid electrolyte layer according to this disclosure may have desired or improved electrical properties and desired or improved atmospheric stability.

[0144] Although embodiments of the present invention have been described above with reference to the attached drawings, the present invention may be implemented in other specific forms without changing its technical concept or essential features. Therefore, the embodiments described above should be understood to be illustrative in all respects and not limiting. [Explanation of Symbols]

[0145] 100 Positive electrode layer 110 Positive electrode current collector 120 Cathode active material layer 200 Negative electrode layer 210 Negative electrode current collector 220 Coating layer 300 solid electrolyte layer 310 First solid electrolyte layer 320 Second solid electrolyte layer ADT additive BND Binder SSE solid electrolyte

Claims

1. It comprises a sulfide-based solid electrolyte, a binder, and additives. The aforementioned additive includes metal acetylacetonate. Solid electrolyte layer.

2. The central metal of the metal-acetylacetonate includes at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), manganese (Mn), zirconium (Zr), tin (Sn), zinc (Zn), chromium (Cr), or a combination thereof. The solid electrolyte layer according to claim 1.

3. At least one attractive force acts between the additive and the sulfide-based solid electrolyte, or between the additive and the binder. The solid electrolyte layer according to claim 1.

4. The content of the additive is in the range of 0.1 to 1.5 parts by weight per 100 parts by weight of the solid electrolyte layer. The solid electrolyte layer according to claim 1.

5. The weight ratio of the binder to the additive is in the range of 1:0.01 to 1:0.

5. The solid electrolyte layer according to claim 1.

6. The content of the sulfide-based solid electrolyte is in the range of 90 to 99 parts by weight per 100 parts by weight of the solid electrolyte layer. The solid electrolyte layer according to claim 1.

7. The sulfide-based solid electrolyte is Li 7-x PS 6-x Cl x (0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (0 ≤ x ≤ 2), Li 7-x PS 6-x I x (0 ≤ x ≤ 2), Li 7-y M1 y PS 6-z M2 z (0 ≤ x ≤ 2, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 2), or includes at least one of these combinations The aforementioned M1 includes one or more elements selected from groups 3 to 15 of the periodic table. The aforementioned M2 includes one or more elements selected from Group 17 of the periodic table. The solid electrolyte layer according to claim 1.

8. The binder includes at least one of the following: an acrylic binder, a fluorine-based binder, a rubber-based binder, or a combination thereof. The solid electrolyte layer according to claim 1.

9. The binder comprises at least one of acrylic rubber, acrylonitrile rubber, polyacrylonitrile, polymethyl methacrylate, polymethyl acrylate, polymethyl acrylate, and polyacrylic acid, or a combination thereof. The solid electrolyte layer according to claim 1.

10. Further containing a dispersant, The solid electrolyte layer according to claim 1.

11. The solid electrolyte layer, positive electrode, and negative electrode described in claim 1 are included, The solid electrolyte layer is disposed between the positive electrode and the negative electrode. All-solid-state battery.

12. The positive electrode comprises a positive electrode active material and a sulfide-based solid electrolyte. The all-solid-state battery according to claim 11.

13. The negative electrode includes a negative electrode current collector and a coating layer on the negative electrode current collector. The coating layer comprises a carbon-based material and a metal. The all-solid-state battery according to claim 11.

14. The carbon-based material includes at least one of the following: carbon black (CB), acetylene black (AB), furnace black (FB), Ketzen black (KB), graphene, or a combination thereof. The aforementioned metal includes at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof. The all-solid-state battery according to claim 13.

15. The negative electrode further includes a lithium metal layer between the negative electrode current collector and the coating layer. The all-solid-state battery according to claim 13.

16. The process involves mixing a sulfide-based solid electrolyte, a binder, additives, and a solvent to form a solid electrolyte slurry. Coating the aforementioned solid electrolyte slurry onto a substrate, This includes drying the coated solid electrolyte slurry, The aforementioned additive includes metal acetylacetonate. A method for manufacturing a solid electrolyte layer.

17. The central metal of the metal-acetylacetonate includes at least one of aluminum (Al), boron (B), iron (Fe), copper (Cu), nickel (Ni), gallium (Ga), manganese (Mn), zirconium (Zr), tin (Sn), zinc (Zn), chromium (Cr), or a combination thereof. A method for producing a solid electrolyte layer according to claim 16.

18. The solvent comprises at least one of xylene, benzene, toluene, pentane, hexane, cyclic hexane, octyl acetate, nonyl acetate, isobutyl isobutyrate (IBIB), or a combination thereof. A method for producing a solid electrolyte layer according to claim 16.

19. The aforementioned sulfide-based solid electrolyte is Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), Li 7-x PS 6-x I x (0≦x≦2), Li 7-y M1 y PS 6-z M2 z (0 ≤ x ≤ 2, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 2), or including at least one combination thereof, The aforementioned M1 includes one or more elements selected from groups 3 to 15 of the periodic table. The aforementioned M2 includes one or more elements selected from Group 17 of the periodic table. A method for producing a solid electrolyte layer according to claim 16.

20. The weight ratio of the additive to the binder in the solid electrolyte slurry is in the range of 1:0.01 to 1:0.

5. A method for producing a solid electrolyte layer according to claim 16.

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