Elastic sheet for for all solid-state battery and all solid-state battery including same

Abstract

The present invention relates to an elastic sheet for an all solid-state battery and an all solid-state battery comprising same, wherein the elastic sheet comprises a binder and a spherical polymer having a sphericity of 0.6 to 0.95. Accordingly, the elastic sheet for an all solid-state battery can apply uniform pressure to an electrode laminate, and can provide safety in the event of an external impact, and thus can provide an all solid-state battery exhibiting excellent charge and discharge characteristics and safety. In addition, provided is an all solid-state battery comprising: a positive electrode; a negative electrode; a solid electrolyte layer positioned between the positive electrode and the negative electrode; and an elastic sheet positioned to the outside of at least one of the positive electrode and the negative electrode.

Description

Elastic sheet for all-solid-state battery and all-solid-state battery comprising the same

[0001] The present invention relates to an elastic sheet for an all-solid-state battery and an all-solid-state battery including the same.

[0002] Recently, rapid developments have been made in electronic devices that use batteries, such as cell phones, laptop computers, and electric vehicles.

[0003] Development of all-solid-state batteries using lithium metal as the cathode is underway. All-solid-state batteries are composed entirely of solid materials, specifically those using solid electrolytes. Because the electrolyte is solid, all-solid-state batteries are structurally robust, reducing the risk of fire or explosion due to leakage from external impacts. Furthermore, they can be shaped into a variety of battery shapes.

[0004] One embodiment provides an elastic sheet for an all-solid-state battery that can apply uniform pressure to an electrode laminate while providing safety against external impact.

[0005] Another embodiment provides an all-solid-state battery comprising the elastic sheet.

[0006] One embodiment provides an elastic sheet for an all-solid-state battery comprising a spherical polymer having a sphericity of 0.6 to 0.95; and a binder.

[0007] Another embodiment provides an all-solid-state battery comprising a positive electrode, a negative electrode, a solid electrolyte layer positioned between the positive electrode and the negative electrode, and an elastic sheet positioned on the outside of at least one of the positive electrode and the negative electrode.

[0008] An elastic sheet for an all-solid-state battery according to an embodiment can apply uniform pressure to an electrode laminate and provide safety in the event of an external impact, thereby providing an all-solid-state battery exhibiting excellent charge / discharge characteristics and safety.

[0009] Figure 1 is a schematic diagram schematically showing an all-solid-state battery according to one embodiment.

[0010] Figure 2 is a schematic cross-sectional view schematically showing an all-solid-state battery according to another embodiment.

[0011] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0012] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0013] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0014] It should be understood that terms such as "include," "comprise," or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0015] Throughout this specification, when it is said that a part "includes" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0016] In addition, the terms "about", "substantially", etc. used throughout this specification are used in the sense of numerical values ​​or near numerical values ​​when manufacturing and material tolerances inherent to the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0017] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0018] Unless otherwise specified herein, when a part such as a layer, film, region, or plate is said to be “on top of” another part, this includes not only cases where it is “directly on top of” the other part, but also cases where there are other parts in between.

[0019] In the present invention, "particle size" or "particle diameter" may be an average particle diameter. In addition, the average particle diameter may be defined as the average particle diameter (D50) based on 50% of the cumulative volume in a particle diameter distribution curve. The particle diameter may be measured by a method widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope, a scanning electron microscope, or a field emission scanning electron microscope (FE-SEM). Alternatively, the average particle diameter (D50) may be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from this. Alternatively, the average particle diameter (D50) may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed 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 ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle diameter (D50) based on 50% of the particle diameter distribution in the measuring device can be calculated.

[0020] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0021] One embodiment provides an elastic sheet for an all-solid-state battery. This elastic sheet may be expressed as a buffer layer or an elastic layer. The elastic sheet ensures that pressure is uniformly transmitted to the electrode stack of a negative electrode, a solid electrolyte, and a positive electrode, thereby improving contact between the solid components and also alleviating stress transmitted to the solid electrolyte, etc. In addition, the elastic sheet serves to cushion changes in the thickness of the electrode during charging and discharging.

[0022] An elastic sheet for an all-solid-state battery according to one embodiment comprises a spherical polymer having a sphericity of 0.6 to 0.95; and a binder.

[0023] In one embodiment, the spherical polymer refers to a polymer having a spherical shape, and may be, for example, a particle having a spherical shape. In one embodiment, the spherical polymer may be a particle having a sphericity of 0.6 to 0.95. In one embodiment, the sphericity may be 0.67 to 0.95, or may be 0.83 to 0.95. In addition, the sphericity may be 0.83 to 0.91.

[0024] In one embodiment, the sphericity can be determined by measuring the polymer particle with an SEM and calculating the ratio of the lengths of two axes from the SEM. Here, the two axes refer to two axes that pass through the center of the polymer particle and intersect at a substantially 90 degree angle.

[0025] For example, since the polymer according to one embodiment has a spherical shape, it may be substantially circular, but since the degree of sphericity is at most 0.95, it may be elliptical.

[0026] Since the polymer according to one embodiment has a spherical shape, it is defined only by the length of the major axis and the minor axis, which are the horizontal and vertical lengths, and the length corresponding to the thickness is not defined.

[0027] Since the elastic sheet includes a polymer having a spherical shape, it can have cushioning properties. When stress is applied to the elastic sheet in the thickness direction, the elastic sheet can absorb the stress well, preventing the stress from being transmitted to the electrode assembly. Therefore, safety can be improved. In addition, the elastic sheet formed of a polymer having a spherical shape has a relatively isotropic elastic modulus and other properties compared to other shapes, and can uniformly apply pressure to the electrode assembly.

[0028] In one implementation example, when the sphericity is outside of 0.6 to 0.95, it is difficult to apply pressure uniformly and isotropy is reduced, which is not suitable.

[0029] In one embodiment, the particle size of the spherical polymer may be 0.1 μm to 10 μm, 0.1 μm to 8 μm, or 0.5 μm to 6 μm. When the sphericity of the spherical polymer satisfies the above range and the particle size falls within the above range, a more uniform pressurizing effect can be obtained.

[0030] In one embodiment, the polymer constituting the spherical polymer may be polyethylene, a polyacrylic polymer, polyurethane, or a combination thereof. The polyacrylic polymer may be polyacrylic acrylate, polyacrylic methacrylate, or a combination thereof.

[0031] These polymers have a cushioning function, which can have the advantage of relieving stress applied to the battery. This advantage can be achieved only when the polymer is spherical. If the polymer is not spherical, for example, linear, and particularly if the degree of sphericity is outside of 0.6 to 0.95, the structural anisotropy of the polymer particles makes it impossible to achieve a cushioning effect.

[0032] In one embodiment, the content of the spherical polymer relative to 100 wt% of the entire elastic sheet may be 10 wt% to 70 wt%, 20 wt% to 60 wt%, or 30 wt% to 50 wt%. When the content of the spherical polymer is within the above range, it can be more uniformly dispersed and included within the elastic sheet and can be better mixed with the binder.

[0033] In one embodiment, the binder serves to cohesively bind the spherical polymers together, and is an elastic material that can perform this role, and its type is not particularly limited.

[0034] For example, the binder may include polyurethane, fluorinated polymer, acrylate resin, natural rubber, spandex, isobutylene isoprene rubber (IIR), ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), chloroprene, elastomer, rubber epichlorohydrin, nylon, terpene, isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), halogenated butyl rubber, neoprene, or copolymers thereof.

[0035] The above polyurethane refers to a homopolymer or copolymer having a urethane group. The above silicone may also be called silicone rubber or silicone resin and refers to a homopolymer or copolymer containing silicon, and the above fluorine-based polymer refers to a homopolymer or copolymer containing fluorine.

[0036] In addition, the binder may be a polyether polyol, and the polyether polyol may have a functional group number of 2 to 4 and a number average molecular weight of 2000 or more and 4000 or less.

[0037] Polyester polyols may also be used as the above binder. Examples of polyester polyols include those obtained by condensation of low-molecular-weight polyols such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, diglycerin, sorbitol, and sucrose with succinic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, succinic anhydride, maleic anhydride, and phthalic anhydride. In addition, examples of polyester polyols include polyols that are ring-opening condensates of caprolactone and methyl valerolactone, which are classified as lactone esters. Examples of polycarbonate polyols include those obtained by dealcoholization reaction of polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol with dialkyl carbonate, dialkylene carbonate, and diphenyl carbonate. As polyester polyols, those having 2 to 3 functional groups and a number average molecular weight of 500 or more and 1000 or less (or a hydroxyl value of 112 mgKOH / g or more and 224 mgKOH / g or less) are more preferable.

[0038] The above acrylate resin may be derived from, for example, a C1 to C20 alkyl (meth)acrylate, a hydroxy C1 to C20 alkyl (meth)acrylate, or a combination thereof.

[0039] Here, C1 to C20 refer to the number of carbon atoms in the alkyl group, and may be, for example, C1 to C18, C1 to C15, C1 to C12, C1 to C10, C1 to C8, C1 to C5. Here, (meth)acrylate refers to acrylate or methacrylate.

[0040] The C1 to C20 alkyl (meth)acrylate may be, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylpentyl (meth)acrylate, 2-ethylheptyl (meth)acrylate, 2-ethylnonyl (meth)acrylate, 2-propylhexyl (meth)acrylate, and 2-propyloctyl (meth)acrylate, or a combination thereof.

[0041] The above hydroxy C1 to C20 alkyl (meth)acrylate may be, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, or a combination thereof.

[0042] For example, the acrylate resin may be derived from a C1 to C20 alkyl (meth)acrylate and a hydroxy C1 to C20 alkyl (meth)acrylate, and at this time, the mixing ratio of the C1 to C20 alkyl (meth)acrylate and the hydroxy C1 to C20 alkyl (meth)acrylate may be a weight ratio of 20:80 to 90:10, for example, a weight ratio of 30:70 to 90:10, 40:60 to 90:10, 50:50 to 90:10, 60:40 to 80:20. In this case, the acrylate resin may exhibit appropriate adhesiveness and is advantageous in realizing excellent compressive strength, stress relaxation rate, and recovery rate.

[0043] The above acrylate resin may further include other repeating units derived from acrylic acid, an alkoxy group-containing acrylate, etc. In addition, the weight average molecular weight of the above acrylate resin may be from 400,000 to 2,000,000, but is not limited thereto.

[0044] The content of the binder relative to 100 wt% of the entire elastic sheet may be 30 wt% to 90 wt%, 40 wt% to 80 wt%, or 50 wt% to 70 wt%. When the content of the binder is within the above range, it may have the advantage of being able to be uniformly dispersed and mixed with the spherical polymer particles while simultaneously providing uniform stress relaxation and pressurization.

[0045] An elastic sheet according to one embodiment may further include suitable additives in addition to the aforementioned components. For example, the additives may be cross-linking agents (e.g., silica, polyisocyanate compounds), tackifiers (e.g., terpenes, phenols, etc.), etc.

[0046] Each additive may be included in an appropriate amount according to the intended purpose, and there is no need to limit it.

[0047] In one embodiment, the thickness of the elastic sheet may be 50 μm to 800 μm, for example, 50 μm to 600 μm, 50 μm to 500 μm, or 150 μm to 500 μm. When the thickness of the elastic sheet is within the above range, the stress due to pressing and the stress due to thickness change during charging and discharging can be sufficiently alleviated, and excellent restoring force can be exhibited.

[0048] <Method for manufacturing elastic sheets>

[0049] A composition for an elastic sheet is prepared by mixing a spherical polymer and a binder in a solvent. The solvent may be toluene, benzene, or a combination thereof.

[0050] The above composition for elastic sheets is applied to a substrate and photopolymerized (or photocured) or thermally polymerized (or thermally cured) to produce an elastic sheet. A polyethylene terephthalate (PET) film can be used as the substrate.

[0051] The above photopolymerization (or photocuring) is carried out with ultraviolet rays at 1000 mJ / cm 2 M to 3000 mJ / cm2 It can be carried out by examining the amount of light. In addition, the thermal polymerization (or thermal curing) can be carried out by heat treatment at 70°C to 120°C.

[0052] [All-solid-state battery]

[0053] Another embodiment provides an all-solid-state battery comprising the elastic sheet. The all-solid-state battery comprises a positive electrode, a negative electrode, a solid electrolyte layer positioned between the positive electrode and the negative electrode, and the elastic sheet positioned on the outer side of at least one of the positive electrode and the negative electrode.

[0054] The above elastic sheet may be positioned on the outermost layer surface of the electrode assembly, or in a structure in which two or more electrode assemblies are laminated, it may be positioned on the outermost layer and / or inside the assembly. Considering that the thickness of the negative electrode in particular changes significantly during charge and discharge due to reasons such as dendrite formation, the elastic sheet may be positioned on the outer side of the negative electrode, i.e., on the opposite side of the surface of the negative electrode where the solid electrolyte layer is in contact, so as to buffer problems caused by thickness changes. In addition, by positioning the elastic sheet on the outer side of the positive electrode and / or the negative electrode, the phenomenon of deterioration due to reaction with lithium may be prevented, thereby increasing the Coulombic efficiency of the battery.

[0055] <Cathode>

[0056] The above cathode includes a current collector and a cathode layer positioned on one surface of the current collector.

[0057] The above negative electrode layer may be a negative electrode active material layer or a negative electrode coating layer. Alternatively, the above negative electrode layer may be a lithium metal layer.

[0058] In one embodiment, the negative electrode coating layer refers to a layer that helps lithium ions released from the positive electrode active material during charge / discharge of an all-solid-state battery to move toward the negative electrode and be deposited on the surface of the current collector. That is, a lithium-containing layer, for example, a lithium deposition layer, is formed between the current collector and the negative electrode coating layer due to the deposition of lithium ions, and the lithium deposition layer functions as a negative electrode active material. Such a negative electrode is generally referred to as a deposition-type negative electrode. The metal and amorphous carbon included in the negative electrode coating layer do not function as a negative electrode active material that directly participates in a charge / discharge reaction. Such a deposition-type negative electrode does not include a negative electrode active material when assembling a battery, but refers to a negative electrode in which the lithium-containing layer functions as a negative electrode active material.

[0059] That is, a lithium-containing layer can be formed between the current collector and the negative electrode coating layer.

[0060] The cathode coating layer may include a metal, a carbon-based material, or a combination thereof that acts as a catalyst. For example, the cathode coating layer may include a metal supported on a carbon-based material, or a mixture of a metal and a carbon-based material. In one embodiment, the cathode coating layer may include a metal and a carbon-based material.

[0061] The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, or may be amorphous carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, carbon nanotubes, graphene, or a combination thereof. The crystalline carbon may be in the form of amorphous, plate-like, flake-like, spherical, or fibrous particles. The amorphous carbon may be, for example, carbon black, acetylene black, Denka black, Ketjen black, furnace black, activated carbon, graphene, or a combination thereof. An example of the carbon black is Super P (Timcal). The amorphous carbon is not limited thereto, and any material classified as amorphous carbon in the relevant field may be used.

[0062] In one embodiment, the carbonaceous material may be a single particle, or may be an assembly having a secondary particle form in which primary particles are assembled. When the carbonaceous material is a single particle, the size of the carbonaceous material may be a nano-size with an average particle diameter of 100 nm or less, for example, 10 nm to 100 nm.

[0063] Additionally, when the carbon-based material is an assembly, the particle size of the primary particles may be 20 nm to 100 nm, and the particle size of the secondary particles may be 1 μm to 20 μm.

[0064] In one embodiment, the particle size of the primary particles may be 20 nm to 100 nm, 20 nm to 90 nm, 20 nm to 80 nm, or 30 nm to 70 nm.

[0065] In one embodiment, the particle size of the secondary particles may be 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 μm.

[0066] The shape of the primary particles may be spherical, elliptical, plate-shaped, or a combination thereof, and in one embodiment, the shape of the primary particles may be spherical, elliptical, or a combination thereof.

[0067] The above metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof. As the cathode coating layer includes the above metal, the electrical conductivity of the cathode can be further improved.

[0068] The metal may be a nanoparticle, and the size of the metal nanoparticle may be, for example, an average size of 5 nm to 800 nm, 5 nm to 700 nm, 5 nm to 500 nm, or 5 nm to 300 nm, but is not limited thereto, and any nanometer-sized particle may be appropriately used. When the metal nanoparticle having such a nanosize is used, the battery characteristics (e.g., life characteristics) of the all-solid-state battery can be improved. When the metal particle size increases to the micrometer level, the uniformity of the metal particles in the negative electrode coating layer decreases, so that the current density in a specific region increases and the cycle life characteristics may deteriorate, which is not appropriate.

[0069] In one embodiment, when the cathode coating layer includes a mixture of a metal and a carbon-based material, the content of the metal may be 1 wt% to 40 wt%, 3 wt% to 30 wt%, 4 wt% to 25 wt%, 5 wt% to 20 wt%, or 5 wt% to 15 wt%, based on 100 wt% of the total mixture.

[0070] Additionally, the carbonaceous material may be present in an amount of 60 wt% to 99 wt%, 70 wt% to 97 wt%, 75 wt% to 96 wt%, 80 wt% to 95 wt%, or 85 wt% to 95 wt% based on 100 wt% of the total mixture.

[0071] The above cathode coating layer may further include a binder. The binder may be a non-aqueous binder.

[0072] The non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, polyacrylate, or combinations thereof.

[0073] The binder may be present in an amount of 1 wt% to 15 wt% relative to 100 wt% of the total cathode coating layer. For example, the binder may be present in an amount of 1 wt% to 14 wt%, 1 wt% to 12 wt%, 1 wt% to 10 wt%, 2 wt% to 8 wt%, or 2 wt% to 7 wt% relative to 100 wt% of the total cathode coating layer.

[0074] When the above binder is included in the negative electrode coating layer of the all-solid-state battery in the above content range, the electrical resistance and adhesive strength can be improved, thereby improving the characteristics (battery capacity and output characteristics) of the all-solid-state battery.

[0075] The above cathode coating layer may further include a solid electrolyte, and the solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

[0076] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n(m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga In), Li a M b P c S d A e (a, b, c, d and e are each integers greater than or equal to 0 and less than or equal to 12, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I). The sulfide-based solid electrolyte may be, for example, Li 7-x PS 6-x F x (0≤x≤2), 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 (0≤x≤2) can be. Also, specifically, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0077] In one embodiment, the sulfide-based solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte. The argyrodite-type sulfide-based solid electrolyte may be, for example, Li a M b P c S d A e(a, b, c, d, and e are all 0 or greater and 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I).

[0078] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li6PS5I, Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or combinations thereof, but are not limited thereto.

[0079] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0080] Methods for mixing sulfur-containing raw materials for manufacturing sulfide-based solid electrolytes include mechanical milling and solution methods. Mechanical milling involves placing the starting raw materials in a reactor and vigorously stirring them with a ball mill, thereby finely agitating the starting raw materials and mixing them. Using the solution method, the starting raw materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can solidify the crystals of the solid electrolyte and improve ionic conductivity. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them twice or more, in which case a sulfide-based solid electrolyte with high ionic conductivity and robustness can be manufactured.

[0081] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0082] The above oxide-based solid electrolyte is, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti yO3(PLZT)(0 x<1, 0≤y<1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr, x is an integer from 1 to 10), or a mixture thereof.

[0083] The above solid polymer electrolytes include, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonyl imide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, Li3PO4·Li2S·SiS2, Li2S·GeS2·Ga2S3, Li2O.11Al2O3, Na2O.11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(0≤x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q 는 Al 또는Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12 (0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0084] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). As X, for example, F, Cl, Br, and I may be mentioned. In particular, in the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. In addition, as the M, for example, a metal element such as Sc, Y, B, Al, Ga, or In may be mentioned.

[0085] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0086] The above-described cathode coating layer may further include additives such as fillers, dispersants, and ionic conductive agents. In addition, known materials generally used in all-solid-state batteries may be used as fillers, dispersants, and ionic conductive agents that can be included in the cathode coating layer.

[0087] The thickness of the cathode coating layer may be, for example, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 100 µm, or 1 µm to 50 µm, but is not limited thereto.

[0088] The current collector may be, for example, 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, and may be in the form of a foil or sheet. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0089] The current collector may be formed of the metal as a substrate and may further include a thin film formed on the substrate. The thin film may include an element capable of forming an alloy with lithium, and may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or a combination thereof, but is not limited thereto, and any element capable of forming an alloy with lithium in the art may be used. When the current collector further includes a thin film, when the lithium-containing layer is formed by precipitation during charging, a more planarized lithium-containing layer may be formed, thereby further improving the cycle life of the all-solid-state battery.

[0090] The thickness of the above thin film may be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thin film thickness is within the above range, the cycle life characteristics can be further improved.

[0091] According to one embodiment, the negative electrode may further include a lithium-containing layer formed during initial charging after battery manufacturing, between the current collector and the negative electrode coating layer. The thickness of the lithium-containing layer may be 1 µm to 1000 µm, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 150 µm, 1 µm to 100 µm, or 1 µm to 50 µm. When the thickness of the lithium-containing layer is within the above range, the lithium storage function may be appropriately performed, and there may be an advantage of further improving the lifespan.

[0092] The lithium-containing layer can be formed when lithium ions are released from the positive electrode active material during charging after the battery is manufactured, pass through the solid electrolyte, and move toward the negative electrode, resulting in lithium being precipitated and deposited on the current collector.

[0093] The above charging process may be a chemical reaction process performed once to three times at 0.05C to 1C at about 25°C to 50°C. When lithium is precipitated and deposited to form a lithium-containing layer, the lithium contained in the lithium-containing layer is ionized and moves toward the positive electrode during discharge, so that the lithium can be used as an anode active material.

[0094] In one embodiment, since the lithium-containing layer is positioned between the current collector and the negative electrode coating layer, the negative electrode coating layer can serve as a protective layer for the lithium-containing layer, thereby inhibiting the precipitation and growth of lithium dendrites. This can suppress short-circuiting and capacity degradation of the all-solid-state battery, and consequently improve the cycle life of the all-solid-state battery.

[0095] The above negative electrode active material layer includes a negative electrode active material, may include a binder, and may further include a conductive material.

[0096] The above negative active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0097] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0098] As the above lithium metal alloy, an alloy of lithium and one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0099] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and the Si-based negative electrode active material may be silicon, a silicon-carbon composite, or SiO. x (0 <x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소, 또는 이들의 조합에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소, 또는 이들의 조합에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 또는 이들의 조합일 수 있다.

[0100] The silicon-carbon composite may include, for example, silicon particles and an amorphous carbon coating layer formed on the surface of the silicon particles. For example, the Si-C composite may include secondary particles in which silicon primary particles are assembled and an amorphous carbon coating layer positioned on the surface of the secondary particles. Amorphous carbon may also be positioned between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. In addition, the Si-C composite may include a core in which silicon particles are dispersed within an amorphous carbon matrix and an amorphous carbon coating layer coating the surface of the core.

[0101] The above silicon primary particles may be nano silicon particles. The particle size of the nano silicon particles may be 10 nm to 1,000 nm, and according to another embodiment, 20 nm to 900 nm, 20 nm to 800 nm, 20 nm to 500 nm, 20 nm to 300 nm, or 20 nm to 150 nm. When the average particle size of the silicon particles is within the above range, excessive volume expansion during charge and discharge can be suppressed, and disconnection of the conductive path due to particle fragmentation during charge and discharge can be prevented. The particle size of the silicon secondary particles need not be particularly limited.

[0102] When the Si-C composite includes silicon particles and an amorphous carbon coating layer, the content of the silicon particles may be 30 wt% to 70 wt%, or 40 wt% to 65 wt%, based on 100 wt% of the total silicon-carbon composite. In addition, the content of the amorphous carbon coating layer may be 30 wt% to 70 wt%, or 35 wt% to 60 wt%, based on 100 wt% of the total silicon-carbon composite.

[0103] The above Si-C composite may further include crystalline carbon. When the Si-C composite further includes crystalline carbon, it may include an assembly in which silicon particles and crystalline carbon are assembled, and an amorphous carbon coating layer positioned on the surface of the assembly.

[0104] When the Si-C composite further includes crystalline carbon, the content of the silicon nanoparticles may be 20 wt% to 70 wt%, or 25 wt% to 65 wt%, based on 100 wt% of the total Si-C composite. The content of the amorphous carbon may be 25 wt% to 70 wt%, or 25 wt% to 60 wt%, based on 100 wt% of the total Si-C composite, and the content of the crystalline carbon may be 1 wt% to 20 wt%, or 5 wt% to 15 wt%.

[0105] There is no need to specifically limit the particle size of the Si-C composite as long as it is appropriately controlled.

[0106] The thickness of the amorphous carbon coating layer can be appropriately controlled, but may be, for example, 5 nm to 100 nm thick.

[0107] The average particle diameter (D50) of the above silicon particles may be 10 nm to 20 μm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, and at this time, the atomic content ratio of Si:O in the silicon particles, which indicates the degree of oxidation, may be 99:1 to 33:67. The silicon particles may be SiO x It can be a particle, in which case SiO x In the range of x, it can be greater than 0 and less than 2. Here, the average particle diameter (D50) is measured by a particle size analyzer using laser diffraction and means the diameter of particles having a cumulative volume of 50% by volume in the particle size distribution.

[0108] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material can be 1:99 to 90:10 by weight.

[0109] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0110] In one embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. In addition, when the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0111] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may include a non-aqueous binder, an aqueous binder, or a combination thereof.

[0112] The non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0113] The above-mentioned aqueous binder may be styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluoroelastomer, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, or a combination thereof.

[0114] A cellulose-based compound may be used as the negative electrode binder. Furthermore, the cellulose-based compound and the aqueous binder may be used together. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, an alkali metal salt thereof, or a combination thereof. Na, K, or Li may be used as the alkali metal. The cellulose-based compound may function as a binder and as a thickener that increases viscosity. Accordingly, the content of the cellulose-based compound is not specifically limited, but may be, for example, 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0115] The above binders are not limited to these, and any binder used in the relevant technical field may be used, and their content can also be appropriately adjusted.

[0116] The above conductive material is used to impart conductivity to the electrode. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0117] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0118] Bipolar

[0119] According to one embodiment, a positive electrode of an all-solid-state battery includes a positive electrode current collector and a positive electrode active material layer positioned on one surface of the positive electrode current collector.

[0120] The above-described positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may use at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B 1 b O 2-c D 1 c (0.90≤a ≤1.8, 0 ≤b≤0.5, 0≤c≤0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤ c≤05); Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mnb B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor 1-b-c Mn b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); The a Nor b E c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); The a Nor b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); The a NiG b O2( 0.90≤a≤1.8, 0.001≤b≤0.1); The a CoG b O2(0.90≤a≤1.8, 0.001≤b≤ 0.1); The a MnG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); The a Mn2G b O4(0.90≤a≤1.8, 0.001≤b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; The (3-f) J2(PO4)3(0 ≤f≤2); The (3-f)Fe2(PO4)3(0≤f≤2); or LiFePO4.

[0121] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D 1 is O, F, S, P, or a combination thereof, and E is Co, Mn, or a combination thereof; F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I 1 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0122] According to one implementation example, LiNi is used as the positive electrode active material. x Co y Al z O2(NCA), LiNi x Co y Mn z O2(NCM)(but, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1) 등의 삼성분계 리튬 전이 금속 산화물을 들 수 있다.

[0123] Of course, it is also possible to use a compound having a coating layer on the surface of the compound, or it is also possible to use a mixture of the compound and a compound having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, and a hydroxycarbonate of the coating element. The compounds forming these coating layers may be 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 forming process may use any coating method as long as it can coat the compound with these elements in a method that does not adversely affect the properties of the positive electrode active material (for example, spray coating, dipping, etc.), and since this is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0124] In addition, as the above coating layer, any known coating layer for the positive electrode active material of an all-solid-state battery can be applied. For example, it can be a buffer layer that plays a role in lowering the interfacial resistance between the positive electrode active material and the solid electrolyte. For example, the buffer layer can include a lithium-metal-oxide, wherein the metal can be one or more elements selected from the group consisting of Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr. A specific example of the buffer layer can be Li2O-ZrO2 (LZO).

[0125] Furthermore, when the cathode active material is a ternary compound containing nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved and metal dissolution from the cathode active material can be further reduced in a charged state. Consequently, the all-solid-state battery can exhibit improved long-term reliability and cycle performance in a charged state.

[0126] The average particle size of the positive electrode active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. For example, the positive electrode active material may include small particles having an average particle size (D50) of 1 μm to 9 μm and large particles having an average particle size (D50) of 10 μm to 25 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within a positive electrode active material layer and can realize high capacity and high energy density.

[0127] The above-mentioned positive electrode active material may be in the form of a secondary particle formed by agglomeration of a plurality of primary particles, or may be in the form of a single crystal. In addition, the above-mentioned positive electrode active material may be in the form of a spherical or nearly spherical shape, or may be polyhedral or irregular.

[0128] In addition, the content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and may be within a range applicable to the positive electrode layer of a conventional all-solid-state secondary battery. For example, with respect to the total 100 wt% of the positive electrode active material layer, the positive electrode active material may be included in an amount of 55 wt% to 99.5 wt%, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0129] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0130] The above binder may include, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0131] The above binder may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on 100 wt% of the total positive electrode active material layer. Within the above content range, the binder can sufficiently exhibit adhesive ability without deteriorating battery performance.

[0132] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0133] The conductive material may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on 100 wt% of the total weight of the positive electrode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0134] The above-described positive electrode active material layer may additionally include a solid electrolyte. The solid electrolyte included in the positive electrode active material layer may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte. The solid electrolyte included in the positive electrode may be the same as or different from the solid electrolyte included in the positive electrode.

[0135] With respect to the total weight of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. In addition, with respect to the total weight of the positive electrode active material and the solid electrolyte in the positive electrode active material layer, 65 wt% to 99 wt% of the positive electrode active material and 1 wt% to 35 wt% of the solid electrolyte may be included, for example, 80 wt% to 90 wt% of the positive electrode active material and 10 wt% to 20 wt% of the solid electrolyte may be included. When the solid electrolyte is included in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0136] The above anode current collector may include, for example, 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, and may be in the form of a foil or sheet.

[0137] Solid electrolyte layer

[0138] The above solid electrolyte layer includes a solid electrolyte. The solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

[0139] In one embodiment, the inorganic solid electrolyte, such as a sulfide-based solid electrolyte, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte, is as described above.

[0140] The above solid electrolyte is in the form of particles, and the average particle diameter (D50) may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.5 μm to 1.0 μm.

[0141] The above solid electrolyte layer may further include a binder. At this time, the binder may be styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, but is not limited thereto, and any binder used in the relevant technical field may be used. The acrylate polymer may be butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0142] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent for the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the solid electrolyte layer formation process is widely known in the art, a detailed description thereof will be omitted herein.

[0143] The solid electrolyte layer may further comprise an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0144] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt may improve ion conductivity by enhancing the lithium ion mobility of the solid electrolyte layer.

[0145] The above lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0146] In addition, the lithium salt may be an imide-based one, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0147] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0148] The above ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) BF4. - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0149] The ionic liquid may be at least one selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0150] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0151] The above-mentioned all-solid-state secondary battery may be a unit cell having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit cell is repeated.

[0152] The shape of the above-mentioned all-solid-state secondary battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. In addition, the above-mentioned all-solid-state secondary battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0153] FIG. 1 is a cross-sectional view of an all-solid-state battery according to an embodiment. Referring to FIG. 1, the all-solid-state battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative electrode collector (401) and a negative electrode coating layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode collector (201) are laminated is housed in a case such as a pouch. The all-solid-state battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). Although FIG. 2 illustrates one electrode assembly including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies.

[0154] Fig. 2 schematically illustrates an all-solid-state battery according to another embodiment. The all-solid-state battery (100) illustrated in Fig. 2 includes a positive electrode (200) including a positive electrode current collector (201) and a positive electrode active material layer (203), a negative electrode (400) including a current collector (401), a negative electrode coating layer (403), and a solid electrolyte (300) positioned between the positive electrode (200) and the negative electrode (400), and includes a battery case (500) in which these are housed, and further includes a lithium precipitation layer (405') between the current collector (401) and the negative electrode coating layer (403). When the all-solid-state battery is charged, the lithium precipitation layer can be formed by lithium ions being released from the positive electrode active material and deposited on the current collector (401').

[0155] An all-solid-state battery according to one embodiment can be manufactured by a step of preparing a laminate by positioning a cathode, an anode, and a solid electrolyte layer between the cathode and the anode, and pressing the laminate.

[0156] The pressurizing process can be performed at a temperature ranging from 25°C to 90°C. In addition, the pressurizing process can be performed by pressurizing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, 1 MPa to 500 MPa. The pressurizing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressurizing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing.

[0157] Hereinafter, examples and comparative examples of the present invention will be described. The following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0158] (Example 1)

[0159] (1) Manufacturing of elastic sheets

[0160] A composition for an elastic sheet was prepared by mixing 50 wt% of a polyethylene spherical polymer (average particle diameter (D50): 4 ㎛) having a sphericity of 0.9 and 50 wt% of a polyether polyol binder in a toluene solvent.

[0161] The obtained composition was applied to a polyethylene terephthalate (PET) film, which is a release film, and exposed to ultraviolet light at 2000 mJ / cm 2 By investigating the amount of light, an elastic sheet bonded onto a PET film was manufactured.

[0162] (2) Manufacturing of cathode

[0163] Carbon black having a primary particle diameter (D50) of about 30 nm and silver (Ag) having an average particle diameter (D50) of about 60 nm are mixed in a weight ratio of 3:1, and 0.25 g of this mixture is added to 2 g of an N-methyl pyrrolidone solution containing 7 wt% of a polyvinylidene fluoride binder, and mixed to prepare a negative electrode active material layer composition.

[0164] The above negative electrode active material layer composition was applied to a nickel foil current collector using a bar coater and vacuum dried to manufacture a negative electrode.

[0165] (2) Manufacturing of the anode

[0166] LiNi 0.8 Co 0.15 Mn 0.05 A cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.5 wt% of lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of polyvinylidene fluoride binder, and 0.5 wt% of carbon nanotube conductive material in an N-methyl pyrrolidone solvent.

[0167] The manufactured positive electrode composition was coated on an aluminum positive electrode current collector using a bar coater, dried, and rolled to manufacture a positive electrode.

[0168] (3) Manufacturing of solid electrolyte layer

[0169] An isobutyl isobutylate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer, was added to an argyrodite-type solid electrolyte Li6PS5Cl and mixed. At this time, the mixing ratio of the solid electrolyte and the binder was set to a weight ratio of 98.7:1.3.

[0170] The above mixing process was performed using a sinky mixer. 2 mm zirconia balls were added to the resulting mixture and stirred again using the sinky mixer to produce a slurry. The slurry was cast onto a polytetrafluoroethylene film and dried at room temperature to produce a solid electrolyte layer with a thickness of 100 μm.

[0171] (4) Manufacturing of all-solid-state batteries

[0172] After sequentially stacking the manufactured positive electrode, solid electrolyte layer, and negative electrode, the manufactured elastic sheet was stacked on the negative electrode. Subsequently, the negative electrode, solid electrolyte layer, and positive electrode were sequentially stacked to manufacture an assembly in the order of positive electrode / solid electrolyte / negative electrode / elastic sheet / negative electrode / solid electrolyte / positive electrode.

[0173] The above assembly was placed in a laminate film and pressurized at 80°C with a force of 500 MPa to manufacture an all-solid-state battery.

[0174] In a pressurized state, the thickness of the positive active material layer was about 100 μm, the thickness of the negative active material layer was about 7 μm, the thickness of the solid electrolyte layer was about 60 μm, and the thickness of the elastic sheet was about 120 μm.

[0175] (Example 2)

[0176] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a polyethylene spherical polymer (average particle diameter (D50): 4 μm) having a sphericity of 0.67 and 50 wt% of a polyether polyol in a toluene solvent.

[0177] (Example 3)

[0178] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a polyethylene spherical polymer (average particle diameter (D50): 4 μm) having a sphericity of 0.83 and 50 wt% of a polyether polyol in a toluene solvent.

[0179] (Comparative Example 1)

[0180] A composition for an elastic sheet was prepared by mixing a polyether-based polyol binder in a toluene solvent.

[0181] The obtained composition was applied to a polyethylene terephthalate (PET) film, which is a release film, and exposed to ultraviolet light at 2000 mJ / cm 2By investigating the amount of light, an elastic sheet bonded onto a PET film was manufactured.

[0182] (Comparative Example 2)

[0183] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a polyethylene spherical polymer (average particle diameter (D50): 4 μm) having a sphericity of 0.99 and 50 wt% of a polyether polyol in a toluene solvent.

[0184] (Comparative Example 3)

[0185] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a polypropylene spherical polymer (average particle diameter (D50): 4 μm) with a sphericity of 0.5 and 50 wt% of a polyether polyol in a toluene solvent.

[0186] (Comparative Example 4)

[0187] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a fibrous polymer (length: 0.5 μm, diameter: 0.1 μm) of a polyethylene polymer and 50 wt% of a polyether-based polyol binder in a toluene solvent.

[0188] (Comparative Example 5)

[0189] An all-solid-state battery was manufactured in the same manner as in Example 1, except that a composition for an elastic sheet was manufactured by mixing 50 wt% of a polyacrylic rod-shaped polymer having a length ratio of 3:1 (longitudinal / short axis) on one side and a length of 100 nm and 50 wt% of a polyether polyol binder in a toluene solvent.

[0190] Experimental Example 1: Compressive Strength Evaluation

[0191] The compressive strength was measured for the elastic sheets of Examples 1 to 3 and Comparative Examples 1 to 5.

[0192] The above compressive strength measurement was performed using a compression tester with a spherical jig with a diameter of 10 mm, at a compression ratio of 0.6 mm / min (10 μm / sec), to measure the compressive strength when the elastic sheet was compressed to 50% of its original thickness. The results are shown in Table 1 below as CFD 50%.

[0193] Experimental Example 2: Stress Relaxation Rate Evaluation

[0194] The stress relaxation rate was evaluated for the elastic sheets of Examples 1 to 3 and Comparative Examples 1 to 5. The results are shown in Table 1 below. The stress relaxation rate was obtained by measuring the initial stress by first pressing the elastic sheet under a pressure condition of 2.5 kgf, then immediately compressing it a second time to 40 ㎛, and then maintaining it for 60 seconds after the second compression, and measuring the stress according to Equation 2.

[0195] [Formula 2]

[0196] Stress relaxation rate (%) = (Stress after 60 seconds of 40㎛ compression) / (Initial stress at 40㎛ compression) X 100

[0197] Experimental Example 3: Evaluation of Recovery Rate

[0198] The recovery rate was evaluated for the elastic sheets of Examples 1 to 3 and Comparative Examples 1 to 5.

[0199] The above recovery rate was obtained by first pressurizing the elastic sheet under a pressure condition of 2.5 kgf, then immediately compressing it a second time to 40 ㎛, maintaining it for 60 seconds, and calculating the initial stress at the time of the first pressurization and the stress upon returning to the starting point of the second compression (initial point), according to the above equation 3.

[0200] [Formula 3]

[0201] Recovery rate (%) = (Stress when restored to the initial point after 40㎛ compression) / (Initial stress when 40㎛ compressed) X 100

[0202] Experimental Example 4) Life Evaluation

[0203] The all-solid-state batteries manufactured according to the above Examples 1 to 3 and Comparative Examples 1 to 5 were placed in a test module and fixed with a force of 5000 gf, and then charged at a constant current of 0.1 C at 45°C to an upper limit voltage of 4.25 V, and then discharged at 0.1 C to an end voltage of 2.5 V to perform initial charge and discharge.

[0204] The battery, which had undergone initial charge and discharge, was subjected to 300 cycles of charge and discharge at 0.33 C in a voltage range of 2.5 V to 4.25 V at 45°C, and the number of cycles at which the ratio of discharge capacity to initial discharge capacity fell below 90% was defined as the lifespan. The results are shown in Table 1 below.

[0205] CFD 50% (MPa) Stress relaxation rate (%) Recovery rate (%) Life (Cycle) Example 11.515% 81% > 250 Example 21.315% 78% > 250 Example 31.517% 80% > 300 Comparative example 10.83% 70% < 100 Comparative example 20.913% 71% < 250 Comparative example 30.812% 72% < 250 Comparative example 40.79% 69% < 200 Comparative example 50.58% 64% < 200

[0206] As shown in Table 1 above, it can be seen that the elastic sheets of Examples 1 to 3 using spherical polymers having a sphericity of 0.67 to 0.95 exhibit excellent compressive strength, stress relaxation rate, recovery rate, and lifespan characteristics.

[0207] On the other hand, in the case of Comparative Example 1, which did not use a spherical polymer, it was found that the material properties were very deteriorated, with a compressive strength of 0.8 MPa, a stress relaxation rate of 3%, a recovery rate of 70%, and a lifespan of less than 100 cycles.

[0208] In addition, it can be seen that the elastic sheets of Comparative Examples 2 and 3 using spherical polymers with a sphericity outside the range of 0.67 to 0.95 exhibit rather low stress relaxation rates and life characteristics, and very low compressive strengths of 0.8 MPa and 0.7 MPa, respectively.

[0209] It can be seen that the elastic sheets of Comparative Examples 4 and 5 using fibrous polymers or rod-shaped polymers exhibited rather low recovery rates of 69% and 64% and lifespan characteristics of less than 200 cycles, and very low compressive strengths of 0.7 MPa and 0.5 MPa and very low stress relaxation rates of 9% and 8%, respectively.

[0210] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. A spherical polymer having a sphericity of 0.6 to 0.95; and bookbinder An elastic sheet for an all-solid-state battery comprising:

2. In paragraph 1, An elastic sheet for an all-solid-state battery having a sphericity of 0.67 to 0.

95.

3. In paragraph 1, The above-mentioned spherical polymer is an elastic sheet for an all-solid-state battery, which is polyethylene, polyacrylic polymer, polyurethane or a combination thereof.

4. In paragraph 1, An elastic sheet for an all-solid-state battery, wherein the content of the above-mentioned spherical polymer is 10% to 70% by weight based on 100% by weight of the entire elastic sheet.

5. In paragraph 1, An elastic sheet for an all-solid-state battery, wherein the content of the above-mentioned spherical polymer is 20% to 60% by weight based on 100% by weight of the entire elastic sheet.

6. In paragraph 1, An elastic sheet for an all-solid-state battery, wherein the particle size of the above-mentioned spherical polymer is 0.1 μm to 10 μm.

7. In paragraph 1, The above binder is an elastic sheet for an all-solid-state battery, which is selected from the group consisting of polyurethane, fluorinated polymer, acrylate resin, natural rubber, spandex, isobutylene isoprene rubber (IIR), ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), chloroprene, elastomer, rubber epichlorohydrin, nylon, terpene, isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), halogenated butyl rubber, neoprene, or a copolymer thereof.

8. In paragraph 1, The above binder is an elastic sheet for an all-solid-state battery, which is a polyether-based polyol or a polyester-based polyol.

9. In paragraph 1, An elastic sheet for an all-solid-state battery, wherein the thickness of the elastic sheet is 50 μm to 800 μm.

10. Bipolar; cathode; A solid electrolyte layer positioned between the anode and the cathode; and An elastic sheet according to any one of claims 1 to 9, positioned on the outer side of at least one of the positive and negative electrodes. An all-solid-state battery comprising:

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