Slurry for all-solid-state battery, positive electrode for all-solid-state battery, and all-solid-state battery

Abstract

The present invention relates to a slurry for an all-solid-state battery, and a positive electrode for an all-solid-state battery and an all-solid-state battery, manufactured using same. More specifically, the slurry for an all-solid-state battery includes a sulfide-based solid electrolyte, a binder, a non-aqueous solvent, and an additive, wherein the additive may include a cyclic phosphazene compound.

Description

Slurry for all-solid-state batteries, cathode for all-solid-state batteries, and all-solid-state batteries

[0001] The present invention relates to a slurry for an all-solid-state battery, a positive electrode for an all-solid-state battery, and an all-solid-state battery.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Recently, all-solid-state batteries have been proposed in which the liquid electrolyte of lithium-ion batteries is replaced with a solid electrolyte. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, such all-solid-state batteries can possess excellent safety.

[0004] The problem that the present invention aims to solve is to provide a slurry for an all-solid-state battery with excellent dispersibility and phase stability.

[0005] Another problem that the present invention aims to solve is to provide a positive electrode for an all-solid-state battery and an all-solid-state battery having excellent electrical performance and lifespan characteristics.

[0006] A slurry for an all-solid-state battery according to one embodiment of the present invention comprises a sulfide-based solid electrolyte, a binder, a non-aqueous solvent, and an additive, wherein the additive may include a cyclic phosphazene compound.

[0007] A positive electrode for an all-solid-state battery according to one embodiment of the present invention comprises a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a binder, and an additive, and the additive may comprise a cyclic phosphazene compound.

[0008] According to one embodiment of the present invention, an all-solid-state battery comprises: a positive electrode including a positive current collector and a positive active material layer; a negative electrode including a negative current collector; and a solid electrolyte layer between the positive electrode and the negative electrode; wherein at least one of the positive active material layer or the solid electrolyte layer comprises a sulfide-based solid electrolyte, a binder, and an additive, and the additive may comprise a cyclic phosphazene compound.

[0009] The slurry for an all-solid-state battery according to the present invention may have excellent dispersibility and phase stability. The anode or solid electrolyte layer prepared from the all-solid-state battery slurry may have excellent electrical characteristics and excellent lifespan characteristics.

[0010] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0011] FIG. 2 is a schematic diagram of a slurry for an all-solid-state battery according to an embodiment of the present invention.

[0012] FIG. 3 is a schematic diagram of a slurry for an all-solid-state battery according to a comparative example of the present invention.

[0013] FIG. 4 is a cross-sectional view of the enlarged region M of FIG. 1, intended to explain the positive active material layer according to an embodiment of the present invention.

[0014] FIG. 5 is a cross-sectional view of the enlarged region M of FIG. 1, intended to explain the positive active material layer according to a comparative example of the present invention.

[0015] FIG. 6 is a cross-sectional view of the N region of FIG. 1 enlarged to explain a solid electrolyte layer according to an embodiment of the present invention.

[0016] FIG. 7 is a cross-sectional view of the N region of FIG. 1 enlarged to illustrate a solid electrolyte layer according to a comparative example of the present invention.

[0017] FIG. 8 is a plan view of an all-solid-state battery according to embodiments of the present invention.

[0018] Figure 9a is a cross-sectional view along the line A-A' of Figure 8.

[0019] Figure 9b is a cross-sectional view along the line B-B' of Figure 8.

[0020] FIG. 10 is a cross-sectional view along line A-A' of FIG. 8, intended to illustrate an all-solid-state battery according to another embodiment of the present invention.

[0021] Figure 11 is a graph showing the measurement results of the viscosity of the all-solid-state battery slurry of Example 1 of the present invention.

[0022] Figure 12 is a graph showing the measurement results of the viscosity of the all-solid-state battery slurry of Example 2 of the present invention.

[0023] Figure 13 is a graph showing the measurement results of the viscosity of a slurry for an all-solid-state battery of the comparative example of the present invention.

[0024] Figure 14 is a graph showing the measurement results of the storage modulus and loss modulus of the all-solid-state battery slurry of Example 1 of the present invention.

[0025] Figure 15 is a graph showing the measurement results of the storage modulus and loss modulus of the all-solid-state battery slurry of Example 2 of the present invention.

[0026] Figure 16 is a graph showing the measurement results of the storage modulus and loss modulus of a slurry for an all-solid-state battery of the comparative example of the present invention.

[0027]

[0028] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0029] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0030] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0031] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0032] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0033] 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 in the corresponding phrase, or all possible combinations thereof.

[0034] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the 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. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer or by scanning electron microscope images. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0035] In one embodiment, the average particle size in this specification may refer to the diameter measured by randomly selecting about 100 particles from an electron microscope image. Alternatively, the average particle size in this specification may refer to the diameter of a particle that has a cumulative volume of 50% in the particle size distribution, which can be measured by a particle size analyzer.

[0036] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention.

[0037] Referring to FIG. 1, an all-solid-state battery according to one embodiment may include 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, not limited thereto, the all-solid-state battery may further include an additional functional layer, such as an adhesion-enhancing layer, 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).

[0038]

[0039] Slurry (SLL) for all-solid-state batteries

[0040] FIG. 2 is a schematic diagram of a slurry for an all-solid-state battery according to embodiments of the present invention. Referring to FIG. 2, the all-solid-state battery slurry (SSL) according to embodiments of the present invention may comprise a sulfide-based solid electrolyte (SSE), a binder (BND), a non-aqueous solvent (NAS), and an additive (ADT). The additive (ADT) may comprise a cyclic phosphazene compound.

[0041] In this specification, the term "all-solid-state battery slurry (SSL)" may mean a slurry containing a solid electrolyte. The all-solid-state battery slurry (SSL) may mean a solid electrolyte slurry for manufacturing a solid electrolyte layer (300) or a positive active material slurry for manufacturing a positive active material layer (120).

[0042] Sulfide-based solid electrolytes (SSE) are, for example, 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 (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0043] Sulfide-based solid electrolytes (SSE) are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0044] Alternatively, sulfide-based solid electrolytes (SSE) are Li 7-a-c M1 a PS 6-c M2 c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, M2 may be F, Br, Cl, or a combination thereof. M1 may be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0045] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte (SSE) may be, for example, 15 GPa to 35 GPa.

[0046] The non-aqueous solvent (NAS) may be a non-polar organic solvent or a weakly polar organic solvent that has low reactivity with the sulfide-based solid electrolyte (SSE). The non-aqueous solvent (NAS) may include, for example, at least one of xylene, benzene, toluene, pentane, hexane, octyl acetate, nonyl acetate, isobutyl isobutyrate (IBIB), diisopropylbenzene (DIPB), or a combination thereof. Diisopropylbenzene (DIPB) may be, for example, 1,2-diisopropylbenzene (1,2-DIPB), 1,3-diisopropylbenzene (1,3-DIPB), or 1,4-diisopropylbenzene (1,4-DIPB).

[0047] The binder (BND) can bind solid electrolyte particles (SSE) together or bind solid electrolyte particles (SSE) and positive electrode active material particles. The binder (BND) can improve the binding force between the solid electrolyte layer (300) and the positive electrode active material layer (120), or between the positive electrode active material layer (120) and the positive electrode current collector (110).

[0048] The binder (BND) included in the slurry (SSL) for all-solid-state batteries is not particularly limited as long as it can be dissolved in the solvent described above, and may include, for example, fluorine-based binders, rubber-based binders, acrylic-based binders, etc. The binder (BND) may include, for example, polyvinylidenefluoride (PVdF), polyvinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or at least one combination thereof.

[0049] The additive (ADT) may include a cyclic phosphazene compound. The additive (ADT) may include a cyclic phosphazene compound represented, for example, by the following Chemical Formula 1 or Chemical Formula 2.

[0050] [Chemical Formula 1]

[0051]

[0052] [Chemical Formula 2]

[0053]

[0054] X1 to X in the above Chemical Formula 1 and above Chemical Formula 2 14The elements may be the same or different from each other and may each independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen element, or a halogen-containing group. A halogen-containing group may refer to a hydrocarbon group substituted with a halogen element. For example, a halogen-containing group may be an alkyl group having 1 to 5 carbon atoms substituted with a halogen element.

[0055] For example, the additive (ADT) may include at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof.

[0056] The additive (ADT) can interact with the sulfide-based solid electrolyte (SSE) to hinder the aggregation of the binder (BND) and the solid electrolyte (SSE) and improve the dispersibility and phase stability of the all-solid-state battery slurry (SSL). Forces such as electrostatic attraction, van der Waals forces, and weak hydrogen bonding may act between the additive (ADT) and the sulfide-based solid electrolyte (SSE).

[0057] In the additive (ADT) according to the embodiments of the present invention, phosphorus (P) and nitrogen (N) may exist in a resonance form. Since phosphorus (P) has a lower electronegativity compared to nitrogen (N) and halogen elements, phosphorus (P) may carry a positive charge within the additive (ADT). Nitrogen, which has a relatively higher electronegativity, may carry a negative charge. An electrostatic attraction may act between the positively charged phosphorus (P) and the anions within the sulfide-based solid electrolyte (SSE). Specifically, the sulfur anions (S) of the sulfide-based solid electrolyte 2- ), thiophosphate anion (PS 4-x O x 3- Electrostatic attraction may occur between partial positive charges of phosphorus (P) and halogen anions (e.g., Cl, Br, I), where X is an integer from 0 to 3.

[0058] Or a weak van der Waals attraction acts between the phosphazene ring of the additive (ADT) and the surface of the sulfide-based solid electrolyte (SSE), or the nitrogen (N) element of the additive (ADT) interacts with the lithium cations (Li) of the sulfide-based solid electrolyte + It can form weak coordination bonds with ).

[0059] Due to the interaction described above, the additive (ADT) can be positioned on the surface of the sulfide-based solid electrolyte (SSE) to prevent the aggregation of the binder (BND) and the solid electrolyte (SSE). By doing so, the additive (BND) can improve the dispersibility and phase stability of the slurry (SLL) for the all-solid-state battery, and thereby improve the electrical properties of the anode (100) or solid electrolyte layer (300) produced.

[0060] FIG. 3 is a schematic diagram of a slurry for an all-solid-state battery according to a comparative example of the present invention. Referring to FIG. 3, in the all-solid-state battery slurry (SLL) according to the comparative example, the solid electrolyte (SSE) and the binder (BND) may exist in an aggregated cluster state. When the solid electrolyte (SSE) and the binder (BND) aggregate, the dispersibility of the slurry (SLL) is reduced and the imbalance in the particle size distribution increases, which may reduce the phase stability of the slurry.

[0061] When manufacturing a positive active material layer (120) using a slurry with low dispersibility and phase stability, aggregation and sedimentation of particles within the slurry may occur, causing a large variation in the thickness of the positive active material layer (120) and making the composition non-uniform. If the composition of the positive active material layer (120) is non-uniform, non-uniformity in ion conductivity and mechanical strength within the positive active material layer (120) may result, which may lead to a decrease in the electrical characteristics and lifespan of the positive electrode (100).

[0062] Likewise, when manufacturing a solid electrolyte layer (300) using a slurry with low dispersibility and phase stability, aggregation and sedimentation of particles within the slurry may occur, causing a large variation in the thickness of the solid electrolyte layer (300) and an uneven composition. This may lead to a decrease in the ion conductivity and lifespan of the solid electrolyte layer (300).

[0063] Referring again to FIG. 2, in the all-solid-state battery slurry (SLL) according to the embodiment, the additive (ADT) is located on the surface of the sulfide-based electrolyte (SSE) to delay the adsorption phenomenon between the sulfide-based solid electrolyte (SSE) and the binder (BND), suppress aggregation, and improve the dispersibility and phase stability of the slurry.

[0064] The positive active material layer (120) manufactured using the slurry (SLL) according to the embodiments of the present invention may have a small thickness variation and a uniform composition. As a result, the positive electrode (10) may have excellent electrical characteristics and lifespan characteristics. Similarly, the solid electrolyte layer (300) manufactured using the slurry (SLL) according to the embodiments of the present invention may have a small thickness variation, a uniform composition, and excellent ion conductivity.

[0065] In the slurry (SLL) for an all-solid-state battery according to the embodiments of the present invention, the content of the additive (ADT) may be 0.1 to 5.0 parts by weight per 100 parts by weight of the total solid content. If the content of the additive (ADT) is excessive, the additive (ADT) acts as a resistor, which may actually degrade the electrical characteristics of the anode (100) or the solid electrolyte layer (300). If the content of the additive (ADT) is too small, the dispersibility and phase stability of the slurry may not be sufficiently improved.

[0066] In this specification, the solid content of the slurry may refer to all components excluding the solvent. When the slurry (SSL) for an all-solid-state battery is used as a solid electrolyte slurry for manufacturing a solid electrolyte layer (300), the solid content of the slurry may include a sulfide-based solid electrolyte (SSE), a binder (BND), and an additive (ADT). When the slurry (SSL) for an all-solid-state battery is used as a positive active material slurry for manufacturing a positive active material layer (120), the solid content of the slurry may further include a positive active material and a conductive material in addition to the sulfide-based solid electrolyte (SSE), the binder (BND), and the additive (ADT). The solid content in the slurry (SSL) for an all-solid-state battery is not particularly limited and may, for example, be 40 to 80 parts by weight per 100 parts by weight of the total slurry.

[0067] When a slurry (SSL) for an all-solid-state battery is used as a positive active material slurry for manufacturing a positive active material layer (120), the content of the additive (ADT) in the slurry may be 0.1% to 5.0%, 0.1% to 1.0%, or 0.1% to 0.5% based on the total weight of the solid content of the all-solid-state battery slurry.

[0068] When the all-solid-state battery slurry (SSL) is used as a solid electrolyte slurry for manufacturing a solid electrolyte layer (300), the content of the additive (ADT) in the slurry may be 0.1% to 5.0% by weight based on the total weight of the solid content of the all-solid-state battery slurry.

[0069]

[0070] positive electrode (100)

[0071] The positive layer (100) may include a positive current collector (110) and a positive active material layer (120) disposed on the positive current collector (110).

[0072] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising 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.

[0073] Meanwhile, unlike as illustrated in FIG. 1, the positive current collector (110) may be omitted in one embodiment of the present invention. Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0074] FIG. 4 is a cross-sectional view of the enlarged region M of FIG. 1, intended to illustrate a positive active material layer (120) according to embodiments. Referring to FIG. 4, the positive active material layer (120) may include a positive active material (CAM), a sulfide-based solid electrolyte (SSE1), and a binder (BND1). The positive active material layer (120) may further include an additive (ADT1). The additive (ADT1) may include a cyclic phosphazene compound. The positive active material layer (120) according to embodiments of the present invention may be manufactured using the all-solid-state battery slurry (SLL) described above.

[0075] The cathode active material (CAM) may include a material capable of reversibly absorbing and desorbing lithium ions. The cathode active material (CAM) may include, 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, and lithium iron phosphate, as well as nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each cathode active material may be a single material or a mixture of two or more materials.

[0076] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Ni 1-b-c Mn b B c Dα (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, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fIt is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0077] The positive active material (CAM) may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl type) structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mnz O2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질(121)이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0078] The aforementioned compound contained in the positive electrode active material (CAM) may be covered by a coating layer (not shown). The positive electrode active material (CAM) may also be used as a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The method for forming the coating layer is, for example, spray coating or immersion.

[0079] When the positive electrode active material (CAM) contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery is increased, and the metal leaching of the positive electrode active material (120) in the charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery in the charged state are improved. Meanwhile, “cycle characteristics” is a characteristic that indicates the degree of degradation of the all-solid-state battery due to charging and discharging; an all-solid-state battery with high cycle characteristics has a small degree of degradation due to charging and discharging, while an all-solid-state battery with low cycle characteristics may have a large degree of degradation due to charging and discharging.

[0080] The shape of the positive active material (CAM) may include particle shapes such as spheres or ellipsoids. The particle size and content of the positive active material (CAM) are not particularly limited. For example, the content of the positive active material (CAM) may be 80 parts by weight or more and 92 parts by weight or less based on 100 parts by weight of the positive active material layer (120).

[0081] The positive active material layer (120) may include a solid electrolyte. The solid electrolyte in the positive active material layer (120) may include a sulfide-based solid electrolyte (SSE1) with excellent lithium ion conductivity. The sulfide-based solid electrolyte (SSE1) may be the same as or different from the sulfide-based solid electrolyte (SSE) included in the all-solid-state battery slurry (SLL) described above. Alternatively, the sulfide-based solid electrolyte (SSE1) in the positive active material layer (120) may be the same as the solid electrolyte (SSE2) included in the solid electrolyte layer (300) described later.

[0082] For example, sulfide-based solid electrolytes (SSE1) are Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0083] Alternatively, the sulfide-based solid electrolyte (SSE1) is Li 7-a-c M1 a PS 6-c M2 cIt may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, M2 may be F, Br, Cl, or a combination thereof. M1 may be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0084] The sulfide-based solid electrolyte (SSE1) included in the positive electrode active material layer (120) may have a smaller average particle size (D50) compared to the sulfide-based solid electrolyte (SSE2) included in the solid electrolyte layer (300). For example, the average particle size (D50) of the sulfide-based solid electrolyte (SSE1) included 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 (D50) of the sulfide-based solid electrolyte (SSE2) included in the solid electrolyte layer (300). Meanwhile, the average particle size (D50) may be the median diameter measured using a laser particle size distribution meter.

[0085] The binder (BND1) may include a material for bonding the positive active material (CAM), sulfide-based solid electrolyte (SSE1), and conductive material contained in the positive active material layer (120), and for improving the bonding strength with the positive current collector (110). The type of binder (BND1) is not particularly limited and may include, for example, polyvinylidenefluoride (PVdF), vinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or at least one combination thereof.

[0086] The content of the binder (BND1) in the positive active material layer (120) may be 0.5 parts by weight or more and 5 parts by weight or less based on 100 parts by weight of the positive active material layer (120).

[0087] The positive active material layer (120) may further include an additive (ADT1). The additive (ADT1) of the positive active material layer (120) may be the same as or different from the additive (ADT) included in the all-solid-state battery slurry (SLL) described above.

[0088] The additive (ADT1) may include a cyclic phosphazene compound. The additive (ADT1) may include a cyclic phosphazene compound represented, for example, by the following Chemical Formula 1 or Chemical Formula 2.

[0089] [Chemical Formula 1]

[0090]

[0091] [Chemical Formula 2]

[0092]

[0093] X1 to X in the above Chemical Formula 1 and above Chemical Formula 2 14 The elements may be the same or different from each other, and each may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen element, or a halogen-containing group.

[0094] For example, the additive (ADT1) may include at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof.

[0095] The additive (ADT1) can delay the adsorption phenomenon of the sulfide-based solid electrolyte (SSE1) and the binder (BND1) within the positive active material slurry and prevent aggregation, thereby improving the dispersibility and phase stability of the positive active material slurry. The positive active material layer (120) prepared with a slurry having excellent dispersibility and phase stability can have excellent electrical characteristics and excellent lifespan characteristics.

[0096] FIG. 5 is a cross-sectional view of the enlarged region M of FIG. 1, intended to explain a positive active material layer (120) according to a comparative example of the present invention. Referring to FIG. 5, when the positive active material layer (120) does not contain additives, the solid electrolyte (SSE1) and the binder (BND1) within the positive active material layer (120) may exist in an aggregated lump state.

[0097] If the solid electrolyte (SSE1) and the binder (BND1) aggregate and the electrically insulating binder (BND1) is widely distributed around the solid electrolyte (SSE1), contact between the solid electrolyte particles (SSE1) or between the solid electrolyte (SSE1) and the positive electrode active material (CAM) may be obstructed. If contact between the solid electrolyte particles (SSE1) or between the solid electrolyte (SSE1) and the positive electrode active material (CAM) is obstructed, the movement path of lithium ions and the conduction path of electrons are blocked, which may reduce the ion conductivity and electron conductivity of the positive electrode (100).

[0098] The positive active material layer (120) according to the comparative example may have an uneven internal composition because aggregation of internal particles has occurred. If the composition of the positive active material layer (120) is uneven, uneven ion conductivity and mechanical strength within the positive active material layer (120) may result, which may lead to a decrease in the electrical characteristics and lifespan of the positive (100).

[0099] Referring again to FIG. 4, in the positive electrode active material layer (120) according to embodiments of the present invention, the solid electrolyte (SSE1) and the binder (BND1) can exist in an evenly dispersed form without aggregation. If the distribution of the binder (BND1) around the solid electrolyte (SSE1) is reduced, the contact area between the solid electrolyte (SSE1) and the positive electrode active material (CAM) increases, thereby improving lithium ion conductivity. Additionally, factors hindering electron flow are reduced, thereby improving the electron conduction path and enhancing electron conductivity.

[0100] Since the active material layer (120) according to the embodiments of the present invention has a uniform composition, the movement paths of ions and electrons are uniform and local overvoltage is almost non-existent, so it can exhibit excellent electrical characteristics and excellent lifespan characteristics.

[0101] According to embodiments of the present invention, the content of the additive (ADT1) in the active material layer (120) may be 0.1% to 5.0%, 0.1% to 1.0%, or 0.1% to 0.5% with respect to 100% by weight of the positive active material layer (120).

[0102] The additive (ADT1) in the positive active material layer (120) can be identified through FT-IR spectroscopy (Fourier-Transform Infrared Spectroscopy), TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis, or GC-MS (Gas Chromatography-Mass Spectrometry).

[0103] In one embodiment, a sample taken from the positive active material layer (120) is analyzed by FT-IR to obtain a characteristic peak of cyclic phosphazene (e.g., 1200–1300 cm⁻¹). -1 P=N coupled stretching vibration of the region and 800–1000 cm -1 The presence and content of additives can be confirmed by verifying the P=N coupling stretching vibration in the region. In another example, PN can be verified through TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis. + (m / z = 45), P=N + (m / z = 61), N₃P₃ + The presence and content of phosphazene can be confirmed by verifying characteristic ion signals such as (m / z = 213, 215).

[0104] The positive active material layer (120) may further include a conductive material (not shown). The conductive material may have conductivity without causing chemical changes in the all-solid-state battery, thereby increasing the conductivity of the positive active material (CAM) and the solid electrolyte (SSE1).

[0105] 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, and carbon nanotubes.

[0106] Based on 100 parts by weight of solid electrolyte, the positive active material layer (120) may contain 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material decreases, and the electrical conductivity of the positive active material layer (120) may decrease. If the conductive material is included in the positive active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material is excessively high, and a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0107] The positive active material layer (120) may further include, for example, a filler, a coating agent, a dispersant, and an ion-conducting aid in addition to the positive active material (CAM), a sulfide-based solid electrolyte (SSE1), a binder (BND1), an additive (ADT1), and a conductive material described above.

[0108]

[0109] cathode layer (200)

[0110] Referring to FIG. 1, the cathode layer (200) may include a cathode current collector (210) and a coating layer (220) disposed on the cathode current collector (210).

[0111] The negative electrode current collector (210) may provide a reference surface on which the negative electrode active material layer (220) is disposed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. The material constituting the negative electrode current collector (210) may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these, and any material used as an electrode current collector is possible. The thickness of the negative electrode current collector (210) may be 1 to 20 μm, for example 5 to 15 μm, for example 7 to 10 μm.

[0112] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) is, for example, in the form of a plate or foil. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0113] 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) may provide a reference surface on which the coating layer (220) is placed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, 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 an alloy thereof. The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0114] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0115] The coating layer (220) can allow lithium metal to grow between the unit cell and the negative current collector (210) during charging. The coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0116] The coating layer (220) may include metal and carbon. For example, the coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the coating layer (220) may include a mixture of carbon black and silver (Ag).

[0117] The coating layer (220) may further include other additives in addition to metal and carbon. The coating layer (220) may further include at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion-conducting aids.

[0118] The coating layer (220) may have a smaller thickness compared to the positive 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 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, lithium dendrites formed between the coating layer (220) and the negative current collector (210) may collapse the coating layer (220), thereby degrading the cycle characteristics of the all-solid-state battery. If the thickness of the coating layer (220) is excessively increased, the energy density of the all-solid-state battery decreases, and the internal resistance of the all-solid-state battery due to the coating layer (220) increases, thereby degrading the cycle characteristics of the cell. Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the coating layer (220) and the solid electrolyte layer (300).

[0119]

[0120] solid electrolyte layer (300)

[0121] A solid electrolyte layer (300) may be provided between the anode layer (100) and the cathode layer (200). FIG. 6 is a cross-sectional view of the N region of FIG. 1, enlarged to illustrate a solid electrolyte layer (300) according to embodiments of the present invention. Referring to FIG. 6, the solid electrolyte layer (300) according to embodiments of the present invention may include a sulfide-based solid electrolyte (SSE2) and a binder (BND2).

[0122] The sulfide-based solid electrolyte (SSE2) in the solid electrolyte layer (300) may be the same as the solid electrolyte (SSE) included in the aforementioned all-solid-state battery slurry (SLL). For example, the sulfide-based solid electrolyte (SSE2) is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x(0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0123] Alternatively, the sulfide-based solid electrolyte (SSE2) is Li 7-a-c M1 a PS 6-c M2 c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, M2 may be F, Br, Cl, or a combination thereof. M1 may be scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0124] The content of the sulfide-based solid electrolyte (SSE2) in the solid electrolyte layer (300) may be 90 parts by weight or more per 100 parts by weight of the solid electrolyte layer.

[0125] The binder (BND2) may be the same as or different from the binder (BND) included in the all-solid-state battery slurry (SLL) described above. For example, the binder (BND2) may include at least one of polyvinylidenefluoride (PVdF), vinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or a combination thereof, but is not limited thereto.

[0126] The solid electrolyte layer (300) may further include an additive (ADT2). The additive (ADT2) may include a cyclic phosphazene compound. The additive (ADT2) may include, for example, a cyclic phosphazene compound represented by the following chemical formula 1 or chemical formula 2.

[0127] [Chemical Formula 1]

[0128]

[0129] [Chemical Formula 2]

[0130]

[0131] X1 to X in the above Chemical Formula 1 and above Chemical Formula 2 14The elements may be the same or different from each other, and each may independently be hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen element, or a halogen-containing group.

[0132] For example, the additive (ADT2) may include at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof.

[0133] The additive (ADT2) can delay the adsorption phenomenon of the sulfide-based solid electrolyte (SSE2) and the binder (BND2) within the solid electrolyte slurry and prevent aggregation, thereby improving the dispersibility and phase stability of the solid electrolyte slurry. A solid electrolyte layer (300) prepared with a slurry having excellent dispersibility and phase stability can have excellent electrical properties and excellent lifespan characteristics.

[0134] FIG. 7 is a cross-sectional view of the N region of FIG. 1 enlarged to illustrate a solid electrolyte layer (300) according to a comparative example of the present invention. Referring to FIG. 7, when the solid electrolyte layer (300) does not contain additives, the solid electrolyte (SSE2) and the binder (BND2) within the solid electrolyte layer (300) may exist in an aggregated lump state.

[0135] When the solid electrolyte (SSE2) and the binder (BND2) aggregate and the binder (BND2) covers the surface of the solid electrolyte (SSE2) or the spaces between the particles of the solid electrolyte (SSE2), the movement path of lithium ions is blocked, and the ion conductivity of the solid electrolyte layer (300) may be reduced.

[0136] The solid electrolyte layer (300) according to the comparative example may have an uneven internal composition because aggregation of internal particles has occurred. If the composition of the solid electrolyte layer (300) is uneven, unevenness in ion conductivity and mechanical strength within the solid electrolyte layer (300) may result, which may lead to a decrease in the electrical properties and lifespan of the solid electrolyte layer (300).

[0137] Referring again to FIG. 6, in the solid electrolyte layer (300) according to embodiments of the present invention, the solid electrolyte (SSE2) and the binder (BND2) can exist in an evenly dispersed form without aggregation. When the distribution of the binder (BND2) around the solid electrolyte (SSE2) is reduced, the contact area between the solid electrolyte (SSE2) particles increases, and the lithium ion conductivity can be improved.

[0138] The solid electrolyte layer (300) according to the embodiments of the present invention has a uniform composition, so the ion movement path is uniform and there is almost no increase in local resistance, so it can exhibit excellent electrical characteristics and excellent lifespan characteristics.

[0139] According to embodiments of the present invention, the content of the additive (ADT2) in the solid electrolyte layer (300) may be 0.1% to 5.0% by weight with respect to 100% by weight of the solid electrolyte layer (300).

[0140] The additive (ADT2) in the solid electrolyte layer (300) can be identified through FT-IR spectroscopy (Fourier-Transform Infrared Spectroscopy), TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry) analysis, or GC-MS (Gas Chromatography-Mass Spectrometry).

[0141] In the embodiments described below, detailed descriptions of technical features that overlap with those previously described with reference to FIGS. 1 to 7 are omitted, and differences are described in detail.

[0142] FIG. 8 is a plan view of an all-solid-state battery according to embodiments of the present invention. FIG. 9a is a cross-sectional view along line A-A' of FIG. 8. FIG. 9b is a cross-sectional view along line B-B' of FIG. 8.

[0143] Referring to FIGS. 8, 9a, and 9b, 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 anode layer (100), and the second solid electrolyte layer (320) may be adjacent to the cathode layer (200).

[0144] The first solid electrolyte layer (310) may include the first solid electrolyte. The second solid electrolyte layer (320) may include the second solid electrolyte. Each of the first and second solid electrolytes may be the same as the sulfide-based solid electrolyte (SSE2) described above with reference to FIG. 6. For example, each of the first and second solid electrolytes may have a particle shape such as a sphere or an ellipsoid.

[0145] Each of the first solid electrolyte layer (310) and the second solid electrolyte layer (320) may further include a binder. The binder included in the first and second solid electrolyte layers (310, 320) may include, for example, at least one of polyvinylidenefluoride (PVdF), vinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or a combination thereof. there is.

[0146] Each of the first solid electrolyte layer (310) and the second solid electrolyte layer (320) may further include an additive. The additive may be the same as the additive (ADT2) described above with reference to FIG. 6. The additive may include, for example, at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof.

[0147] The second solid electrolyte can come into direct contact with the coating layer (220). By doing so, the second solid electrolyte can suppress lithium dendrites formed between the coating layer (220) and the negative electrode current collector (210). The second solid electrolyte can effectively suppress negative electrode side reactions. This can improve the cell performance of the all-solid-state battery according to the present invention.

[0148] 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 from each other. 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).

[0149] Referring again to FIGS. 8, 9a, and 9b, the anode layer (100) and the first solid electrolyte layer (310) can form an anode composite layer (CSH). The cathode layer (200) and the second solid electrolyte layer (320) can form a cathode composite layer (ASH). An anode composite layer (CSH) can be laminated on the cathode composite layer (ASH).

[0150] The area of ​​the cathode composite layer (ASH) and the area of ​​the anode composite layer (CSH) may differ from each other. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than the area of ​​the anode composite layer (CSH). The anode composite layer (CSH) may completely overlap within the cathode composite layer (ASH).

[0151] In one embodiment of the present invention, the first solid electrolyte layer (310) may have substantially the same area as the anode layer (100). The second solid electrolyte layer (320) may have substantially the same area as the cathode layer (200).

[0152] Specifically, the positive electrode composite layer (CSH) may have a first width (WI1) in a first direction (D1). The negative electrode composite layer (ASH) may have a second width (WI2) in a 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 a second direction (D2). The negative electrode composite layer (ASH) may have a fourth width (WI4) in a second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0153] A unit cell (CEL) according to the present embodiment can be manufactured by forming a negative composite layer (ASH) on a first carrier film, forming an anode composite layer (CSH) on a second carrier film, and then laminating the negative composite layer (ASH) and the anode composite layer (CSH).

[0154] The unit cell (CEL) according to the present embodiment may further include a gasket (GSK). The gasket (GSK) may be provided to surround the positive composite layer (CSH). The gasket (GSK) may fill the step difference on the side of the unit cell (CEL) caused by the difference in area between the negative composite layer (ASH) and the positive composite layer (CSH). The gasket (GSK) may surround the four sides of the positive composite layer (CSH). For example, the thickness of the gasket (GSK) may be substantially the same as or smaller than the thickness of the positive composite layer (CSH). In one embodiment, the positive current collector (110) may be provided at a position higher than the gasket (GSK).

[0155] The positive current collector (110) may include a positive tab (CTB). The positive tab (CTB) may be a protruding area of ​​the positive current collector (110). In one embodiment, the positive tab (CTB) may protrude in a second direction (D2).

[0156] The negative current collector (210) may include a negative tab (ATB). The negative tab (ATB) may be a protruding area of ​​the negative current collector (210). In one embodiment, the negative tab (ATB) may protrude in the opposite direction of the second direction (D2).

[0157]

[0158] FIG. 10 is a cross-sectional view along line A-A' of FIG. 8, illustrating an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 10, the negative electrode layer (200) of a unit cell (CEL) may further include a lithium metal layer (400) between a negative electrode current collector (210) and a coating layer (220). The thickness of the lithium metal layer (400) may increase further during charging of the unit cell (CEL). The coating layer (220) serves as a protective layer for the lithium metal layer (400) and, at the same time, can suppress the growth of lithium dendrites from the lithium metal layer (400).

[0159] The lithium metal layer (400) may include lithium or a lithium alloy. Since the lithium metal layer (400) is a metal layer containing lithium, it may function as, for example, a lithium reservoir. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, but is not limited to these; any alloy used as a lithium alloy in the relevant technical field may be possible. The lithium metal layer (400) may be composed of one of these alloys or lithium, or may be composed 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 current collector (210) during the charging process of the unit cell (CEL), for example.

[0160] In another embodiment of the present invention, a lithium metal layer (400) within the negative electrode (200) may be provided, for example, between the negative electrode current collector (210) and the coating layer (220) 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) acts as a lithium reservoir because it is a metal layer containing 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).

[0161] When a lithium metal layer (400) is deposited by charging after the assembly of the unit cell (CEL), the energy density of the unit cell (CEL) can be increased because the lithium metal layer is not included during the assembly of the unit cell (CEL). When charging the unit cell (CEL), it can be charged beyond the charging capacity of the coating layer (220). That is, the coating layer (220) is overcharged. Lithium can be absorbed in the coating layer (220) at the beginning of charging. When charging beyond the capacity of the coating layer (220), lithium can be deposited, for example, between the negative electrode coating layer (220) and the negative electrode current collector (210). A metal layer (400) can be formed by the deposited lithium.

[0162] The lithium metal layer (400) can be composed mainly of lithium (i.e., metallic lithium). During discharge, the lithium in the lithium metal layer (400) can be ionized and move to the positive electrode (100). In other words, lithium can be used as a negative electrode active material in the unit cell (CEL). In addition, since the coating layer (220) covers the lithium metal layer (400), the coating layer (220) can protect the lithium metal layer (400) and simultaneously suppress the precipitation growth of lithium dendrites. Therefore, the coating layer (220) can suppress short circuits and capacity degradation of the unit cell (CEL) and improve the cycle characteristics of the unit cell (CEL).

[0163] When a lithium metal layer (400) is formed by charging after assembly of a unit cell (CEL), the negative electrode (200), that is, the negative electrode current collector (210) and the coating layer (220) and the region between them may be a Li-free region that does not contain lithium (Li) in the initial state or after complete discharge of the unit cell (CEL).

[0164] The lithium metal layer (400) may have a fifth width (WI5) in the first direction (D1). The fifth width (WI5) may be equal to or greater than the first width (WI1). The fifth width (WI5) may be equal to or smaller than the second width (WI2). For example, the fifth width (WI5) may be greater than the first width (WI1) and smaller than the second width (WI2).

[0165]

[0166] The embodiments of the present invention will be described in more detail below. However, the following embodiments are provided merely to aid in understanding the present invention and do not limit the scope of the present invention.

[0167]

[0168] Example 1

[0169] (Preparation of cathode active material slurry)

[0170] LiNi as the positive active material 0.8 Co 0.1 Al 0.1 O2(NCA) powder was prepared, and a azirodite-based solid electrolyte (Li6PS5Cl) powder was prepared as the sulfide-based solid electrolyte. Vinylidene fluoride / hexafluoropropylene copolymer (PVdF / HFP) was prepared as the binder, and carbon nanofibers (CNF) were prepared as the conductive material. Hexachlorophosphazene was prepared as the additive.

[0171] A cathode active material slurry was prepared by mixing these materials in an octyl acetate solvent in a weight ratio of cathode active material : solid electrolyte : additive : conductive material : binder = 84.8 : 13 : 0.2 : 1 : 1.

[0172] (Anode manufacturing)

[0173] The above positive active material slurry was coated onto an aluminum positive current collector and dried at 130°C for at least 10 minutes to produce a positive electrode.

[0174] (Preparation of solid electrolyte layer)

[0175] A solid electrolyte slurry was prepared by adding an azirodite-based solid electrolyte (Li6PS5Cl) and a polyvinylidene fluoride (PVdF) binder solution to an octyl acetate solvent (the mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight). The prepared solid electrolyte slurry was coated onto a release polytetrafluoroethylene film and dried at 60°C for at least 2 hours to prepare a solid electrolyte layer.

[0176] (Symmetric Coin Cell Manufacturing)

[0177] A symmetric coin cell was manufactured by applying the above-prepared anode equally as the working electrode and the counter electrode, and placing the above-prepared solid electrolyte layer between the two electrodes.

[0178]

[0179] Example 2

[0180] A positive electrode, a solid electrolyte layer, and a symmetric coil cell were prepared in the same manner as in Example 1, except that the positive electrode active material : solid electrolyte : additive : conductive material : binder were mixed in a weight ratio of 84.6 : 13 : 0.4 : 1 : 1 when preparing the positive electrode active material slurry.

[0181]

[0182] Comparative example

[0183] A positive electrode, a solid electrolyte layer, and a symmetric coil cell were prepared in the same manner as in Example 1, except that no additives were added when preparing the positive electrode active material slurry, and the positive electrode active material : solid electrolyte : conductive material : binder were mixed in a weight ratio of 85 : 13 : 1 : 1.

[0184]

[0185] Evaluation Example 1: Evaluation of phase stability of cathode active material slurry

[0186] The rheological properties of the cathode active material slurries prepared according to the examples and comparative examples were measured.

[0187] (1) Measurement of viscosity

[0188] 10 ml of the cathode active material slurry prepared according to the examples and comparative examples was fed into an Anton Paar rheometer to measure the shear viscosity.

[0189] The shear viscosity (viscosity at a shear rate of 10 (1 / s)) of the cathode active material slurries of the examples and comparative examples at room temperature (20°C) was measured immediately after preparation of the slurry and after being left undisturbed for 1 day, respectively, and the results are shown in FIGS. 11 to 13 and Table 1. The viscosity increase rate in Table 1 was calculated according to the following Equation 1.

[0190] <Equation 1>

[0191] Viscosity Increase Rate (%) = [(Shear Viscosity after 1 Day of Unstirred Standing - Shear Viscosity Immediately After Manufacturing) / Shear Viscosity Immediately After Manufacturing] X 100

[0192] Classification Additive Content (wt%) Slurry Viscosity (mPa·s) Viscosity Increase Rate (%) Immediately After Preparation Unstirred 1 Day Example 10.22,278 2,216 -2.72 Example 20.42,184 2,261 3.53 Comparative Example 0.1,956 8,346 326.69

[0193] Referring to FIGS. 11 to 13 and Table 1, it can be seen that the rate of change in viscosity after unstirred storage of the cathode active material slurry according to the embodiments is significantly smaller compared to the cathode active material slurry according to the comparative example. (2) Measurement of storage modulus and loss modulus

[0194] 10 ml of the cathode active material slurry prepared according to the examples and comparative examples was fed into an Anton Paar rheometer to measure the storage modulus (G') and the loss modulus (G"). The storage modulus (G') and the loss modulus (G") were measured immediately after the preparation of the cathode active material slurry and after being left undisturbed for 1 day, respectively, and the results are shown in Figures 14 to 16 below.

[0195] Referring to FIGS. 14 to 16, it can be seen that the positive active material slurry according to the embodiments has a smaller rate of change in storage modulus (G') and loss modulus (G”) immediately after preparation and after unstirred storage compared to the positive active material slurry according to the comparative example. This may mean that the positive active material slurry according to the embodiments has excellent phase stability.

[0196]

[0197] Evaluation Example 2: Evaluation of Electrical Characteristics of the Anode

[0198] The ionic conductivity and electrical conductivity of the anode were evaluated using the symmetric coin cell prepared according to the examples and comparative examples in the following manner.

[0199] Electrochemical Impedance Spectroscopy (EIS) was performed on the symmetric coin cell. The EIS was conducted at an amplitude of approximately 10 mV, a frequency of 10 mHz to 1 MHz, in an air atmosphere at 45°C. The anode plate was a mixed conductor capable of the simultaneous transport of electrons and ions, allowing for the design of a corresponding equivalent circuit. A Nyquist plot was obtained through impedance analysis, and the ionic and electronic conductivity of the anode were isolated from it. The results are shown in Table 2 below.

[0200]

[0201] Classification Additive Content (wt%) Electronic Conductivity (mS / cm) Ionic Conductivity (mS / cm) Example 10.20.3980.048 Example 20.40.3510.039 Comparative Example 00.3230.032

[0202] Referring to Table 2, it can be seen that the anode according to the embodiment has superior ionic conductivity and electronic conductivity compared to the anode according to the comparative example. 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 as illustrative in all respects and not restrictive.

Claims

1. A sulfide-based solid electrolyte, a binder, a non-aqueous solvent, and an additive, wherein The above additive comprises a cyclic phosphazene compound, Slurry for all-solid-state batteries.

2. In Paragraph 1, The above additive comprises a cyclic phosphazene compound represented by the following Chemical Formula 1 or the following Chemical Formula 2, Slurry for all-solid-state batteries: [Chemical Formula 1] [Chemical Formula 2] X1 to X in the above Chemical Formula 1 and above Chemical Formula 2 14 The elements are the same or different from each other and are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen element, or a halogen-containing group.

3. In Paragraph 1, The above additive comprises at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof. Slurry for all-solid-state batteries.

4. In Paragraph 1, The content of the above additive is 0.1 to 5.0 parts by weight per 100 parts by weight of the solid content of the all-solid-state battery slurry, Slurry for all-solid-state batteries.

5. In Paragraph 1, An attractive force acts between the above sulfide-based solid electrolyte and the above additive, Slurry for all-solid-state batteries.

6. In Paragraph 1, The above 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-a-c M1 a PS 6-c M2 c (0≤a≤2, 0≤c≤2) or at least one of a combination thereof, comprising The above M2 is F, Br, Cl, I, or a combination thereof, and the above M1 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 a combination thereof, Slurry for all-solid-state batteries.

7. In Paragraph 1, The above-mentioned non-aqueous solvent comprises at least one of xylene, benzene, toluene, pentane, hexane, octyl acetate, nonyl acetate, isobutyl 2-methylpropanoate (IBIB), diisopropylbenzene (DIPB), or a combination thereof. Slurry for all-solid-state batteries.

8. In Paragraph 1, The binder comprises at least one of polyvinylidenefluoride (PVdF), vinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or a combination thereof. Slurry for all-solid-state batteries.

9. A positive current collector, and a positive active material layer on the positive current collector, wherein The above positive active material layer comprises a positive active material, a sulfide-based solid electrolyte, a binder, and an additive, and The above additive comprises a cyclic phosphazene compound, Cathode for all-solid-state batteries.

10. In Paragraph 9, The above additive comprises at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof. Cathode for all-solid-state batteries.

11. In Paragraph 9, The content of the above additive is 0.1 to 5.0 parts by weight per 100 parts by weight of the above positive active material layer, Cathode for all-solid-state batteries.

12. In Paragraph 9, The above 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-a-c M1 a PS 6-c M2 c (0≤a≤2, 0≤c≤2), or at least one of a combination thereof, comprising The above M2 is F, Br, Cl, I, or a combination thereof, and the above M1 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 a combination thereof, Cathode for all-solid-state batteries.

13. In Paragraph 9, The above positive active material layer further comprises a conductive material, Cathode for all-solid-state batteries.

14. A positive electrode comprising a positive current collector and a positive active material layer; A cathode comprising a cathode current collector; and A solid electrolyte layer between the anode and the cathode; comprising, At least one of the above positive active material layer or the above solid electrolyte layer comprises a sulfide-based solid electrolyte, a binder, and an additive, and The above additive comprises a cyclic phosphazene compound, All-solid-state battery.

15. In Paragraph 14, The above solid electrolyte layer comprises the sulfide-based solid electrolyte, the binder, and the additive, and The above additive comprises a cyclic phosphazene compound represented by the following Chemical Formula 1 or the following Chemical Formula 2, All-solid-state battery: [Chemical Formula 1] [Chemical Formula 2] X1 to X in the above Chemical Formula 1 and above Chemical Formula 2 14 The elements are the same or different from each other and are each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, a halogen element, or a halogen-containing group.

16. In Paragraph 15, The above additive comprises at least one of hexafluorophosphazene, hexachlorophosphazene, hexabromophosphazene, or a combination thereof. All-solid-state battery.

17. In Paragraph 15, The content of the additive in the solid electrolyte layer is 0.1 to 5.0 parts by weight per 100 parts by weight of the solid electrolyte layer, All-solid-state battery.

18. In Paragraph 14, The above 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-a-c M1 a PS 6-c M2 c (0≤a≤2, 0≤c≤2), or at least one of a combination thereof, comprising The above M2 is F, Br, Cl, I, or a combination thereof, and the above M1 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 a combination thereof, All-solid-state battery.

19. In Paragraph 14, The binder comprises at least one of polyvinylidenefluoride (PVdF), vinylidene fluoride / hexafluoropropylene copolymer (PVdF-HFP), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polymethyl acrylate (PMA), polyethyl acrylate (PEA), polybutyl acrylate, polyacrylic acid (PAA), or a combination thereof. All-solid-state battery.

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