Elastic sheet 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 including same, the elastic sheet comprising a (meth)acrylate-based copolymer, aluminum hydroxide, and inorganic nanotubes.

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]

[0003] Lithium secondary batteries are rechargeable and have an energy density per unit weight that is three times higher than that of conventional lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and nickel-zinc batteries, and they are capable of fast charging. Therefore, they are commercialized for use in laptops, cell phones, power tools, and electric bicycles, and active research and development is being conducted to further improve energy density.

[0004] Lithium secondary batteries currently on the market are lithium-ion batteries that use electrolytes containing flammable organic solvents. This poses safety concerns, as they can explode or cause fire in the event of collisions or penetration. Therefore, all-solid-state batteries, which use solid electrolytes instead of the electrolyte, are being proposed.

[0005]

[0006] One embodiment provides an elastic sheet for an all-solid-state battery that suppresses damage to a solid electrolyte during the manufacturing process of the all-solid-state battery or the charging and discharging process of the manufactured all-solid-state battery, while allowing components of an electrode assembly to have a uniform temperature.

[0007] Another embodiment provides an all-solid-state battery comprising the elastic sheet.

[0008]

[0009] One embodiment provides an elastic sheet for an all-solid-state battery, comprising a (meth)acrylate copolymer; aluminum hydroxide; and inorganic nanotubes.

[0010] Another embodiment provides an all-solid-state battery comprising the elastic sheet; and an electrode assembly, wherein the electrode assembly comprises a positive electrode; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and the elastic sheet is positioned on the outside of at least one of the positive electrode and the negative electrode.

[0011]

[0012] An elastic sheet according to one embodiment can improve the life characteristics and coulomb characteristics of an all-solid-state battery by preventing damage to a solid electrolyte during the manufacturing process of an all-solid-state battery or the charging and discharging process of a manufactured all-solid-state battery while allowing components of an electrode assembly to have a uniform temperature.

[0013]

[0014] Figures 1 and 2 are cross-sectional views schematically illustrating an all-solid-state battery according to one embodiment.

[0015]

[0016] 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.

[0017] Unless otherwise specified herein, when a part such as a layer, film, region, plate, etc. is said to be “on” another part, this includes not only cases where it is “directly on” the other part, but also cases where there is another part in between.

[0018] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B."

[0019] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0020] In this specification, (meth)acrylate is a concept that includes acrylate and methacrylate.

[0021] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can 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 the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with 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 size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0022] In this specification, “weight average molecular weight” is a value measured by gel permeation chromatography (GPC: gel permeation chromatography, PL GPC220, Agilent Technologies) and corrected with a third-order function using polystyrene.

[0023] In this specification, “thickness” may be measured by a photograph taken with an optical microscope, such as a scanning electron microscope, or by a thickness measuring device.

[0024]

[0025] (Elastic sheet)

[0026] One embodiment provides an elastic sheet for an all-solid-state battery, comprising a (meth)acrylate copolymer; aluminum hydroxide; and inorganic nanotubes.

[0027] An elastic sheet according to one embodiment can improve the life characteristics and coulomb characteristics of an all-solid-state battery by preventing damage to a solid electrolyte during the manufacturing process of an all-solid-state battery or the charging and discharging process of a manufactured all-solid-state battery while allowing components of an electrode assembly to have a uniform temperature.

[0028]

[0029] Hereinafter, an elastic sheet according to an embodiment is described in detail.

[0030]

[0031] (meth)acrylate copolymer

[0032] The above (meth)acrylate copolymer is a component forming the basic skeleton of an elastic sheet and is a polymer with excellent stress relaxation properties. Accordingly, an elastic sheet comprising the above (meth)acrylate copolymer can improve the lifespan characteristics of an all-solid-state battery by suppressing damage to the solid electrolyte during the manufacturing process of the all-solid-state battery or the charging / discharging process of the manufactured all-solid-state battery.

[0033]

[0034] The above (meth)acrylate copolymer may be a ternary copolymer including a first structural unit derived from a C1 to C20 linear alkyl (meth)acrylate, a second structural unit derived from a C1 to C20 cyclic alkyl (meth)acrylate, and a third structural unit derived from a C1 to C20 alkyl (meth)acrylate containing a hydroxyl group.

[0035]

[0036] With respect to the total amount of the (meth)acrylate copolymer, the first structural unit may be included in an amount of 30 to 70 wt%, or 40 to 60 wt%; the second structural unit may be included in an amount of 5 to 30 wt%, or 10 to 20 wt%; and the third structural unit may be included in an amount of 20 to 50 wt%, or 30 to 40 wt%.

[0037] In the above range, the stress relaxation properties and resilience of the (meth)acrylate copolymer can be excellently expressed.

[0038]

[0039] The above C1 to C20 linear alkyl (meth)acrylate may be 2-ethylhexyl (meth)acrylate, 2-ethylpentyl (meth)acrylate, 2-ethylheptyl (meth)acrylate, 2-ethylnonyl (meth)acrylate, 2-propylhexyl (meth)acrylate, 2-propyloctyl (meth)acrylate, or a combination thereof.

[0040] The above C1 to C20 cyclic alkyl (meth)acrylate may be isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, or a combination thereof.

[0041] The C1 to C20 alkyl (meth)acrylate containing the above hydroxyl group may be 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 (meth)acrylate copolymer may be a copolymer of 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0043]

[0044] The above (meth)acrylate copolymer may have a weight average molecular weight of 400,000 to 2,000,000 g / mol as measured by the GPC method, but is not limited thereto.

[0045]

[0046] aluminum hydroxide

[0047] The above aluminum hydroxide is a component with excellent thermal conductivity properties. Accordingly, the elastic sheet containing the above aluminum hydroxide can improve the Coulomb characteristics of an all-solid-state battery by ensuring that the components of the electrode assembly have a uniform temperature.

[0048]

[0049] Based on 100 parts by weight of the (meth)acrylate copolymer, the aluminum hydroxide may be included in an amount of 100 to 300 parts by weight, or 100 to 200 parts by weight.

[0050] In the above range, the life characteristics and Coulomb characteristics of the all-solid-state battery can be harmoniously improved.

[0051]

[0052] Inorganic nanotubes

[0053] The above-mentioned inorganic nanotubes, like the above-mentioned aluminum hydroxide, are components having excellent thermal conductivity properties.

[0054] In the case of spherical inorganic particles, large quantities are required to bridge different media. In contrast, inorganic nanotubes can bridge different media even in small quantities.

[0055] Accordingly, inorganic nanotubes may be advantageous in thermal conductivity compared to spherical inorganic particles. Furthermore, an elastic sheet containing the inorganic nanotubes may improve the Coulomb characteristics of an all-solid-state battery by ensuring that the components of the electrode assembly maintain a uniform temperature.

[0056]

[0057] The inorganic nanotubes may be boehmite nanotubes, alumina nanotubes, boron nitride nanotubes, or a combination thereof. For example, the inorganic nanotubes may be boehmite nanotubes.

[0058]

[0059] The aspect ratio of the above-mentioned inorganic nanotubes may be 3 or more, 10 or more, 20 or more, or 30 or more. The upper limit of the aspect ratio of the above-mentioned inorganic nanotubes is not particularly limited, but may be 60 or less, 50 or less, or 40 or less.

[0060]

[0061] Based on 100 parts by weight of the (meth)acrylate copolymer, the inorganic nanotubes may be included in an amount of 0.01 to 1 part by weight, or 0.1 to 0.3 parts by weight.

[0062] In the above range, the life characteristics and Coulomb characteristics of the all-solid-state battery can be harmoniously improved.

[0063]

[0064] additives

[0065] The above elastic sheet may further include additives.

[0066] For example, the additive may be a crosslinking agent, an inorganic particle, a flame retardant, a pore former, or a combination thereof.

[0067]

[0068] crosslinking agent

[0069] The crosslinking agent forms a network-structured polymer through intermolecular and / or intramolecular chemical bonds in the (meth)acrylate copolymer. Accordingly, an elastic sheet further comprising the crosslinking agent can have improved resilience.

[0070]

[0071] The crosslinking agent may be a polyfunctional (meth)acrylate.

[0072] For example, the crosslinking agent may be 1,6-hexanediol di(meth)acrylate.

[0073]

[0074] Based on 100 parts by weight of the (meth)acrylate copolymer, the crosslinking agent may be included in an amount of 0.01 to 1 part by weight, 0.05 to 0.5 part by weight, or 0.1 to 0.3 part by weight.

[0075] In the above range, the mechanical properties of the elastic sheet can be improved.

[0076]

[0077] inorganic particles

[0078] An elastic sheet further including the above-described inorganic particles can have improved compressive strength.

[0079]

[0080] The above inorganic particles may be boehmite, alumina, or a combination thereof.

[0081] For example, the inorganic particles may be boehmite.

[0082]

[0083] The shape of the above-mentioned inorganic particles may be spherical, and in this case, D50 may be 100 to 500 nm.

[0084] For example, the inorganic particles may be boehmite.

[0085]

[0086] Based on 100 parts by weight of the above (meth)acrylate copolymer, the inorganic particles may be included in an amount of 30 to 70 parts by weight, or 40 to 60 parts by weight.

[0087] In the above range, the compressive strength of the elastic sheet can be improved.

[0088]

[0089] flame retardants

[0090] The above flame retardant is a substance used to reduce flammability or delay combustion. Accordingly, an elastic sheet further including the flame retardant can have improved flame retardancy.

[0091]

[0092] The above flame retardant may be a phosphorus-based flame retardant or a melamine-based flame retardant.

[0093] For example, the flame retardant may be aluminum diethylphosphinate, which is a type of phosphorus flame retardant.

[0094]

[0095] Based on 100 parts by weight of the (meth)acrylate copolymer, the flame retardant may be included in an amount of 1 to 30 parts by weight, or 5 to 20 parts by weight.

[0096] In the above range, the flame retardancy of the elastic sheet can be improved.

[0097]

[0098] Pore ​​former

[0099] The above-mentioned pore-forming agent can form pores within the elastic sheet. Accordingly, an elastic sheet further comprising the pore-forming agent can be in the form of a foam with pores formed within it. In contrast, an elastic sheet not comprising the pore-forming agent can be in the form of a dense layer without pores formed within it.

[0100] When the elastic sheet is in the form of a foam, its impact resistance and stress relaxation properties can be enhanced. Meanwhile, when the elastic sheet is in the form of a dense layer, its compressive strength and thermal conductivity can be improved. Accordingly, the use of the pore-forming agent can be determined depending on the desired properties.

[0101]

[0102] The pore former may be an inorganic pore former, an organic pore former, or a combination thereof.

[0103] In this specification, the term “hollow” means a shape that is hollow.

[0104] The above-mentioned inorganic pore-forming agent may be a glass microsphere. For example, the glass microsphere may be a glass bubble. The glass bubble may be a hollow particle made of glass.

[0105] The organic pore-forming agent may be a heat-expandable polymer microsphere. The heat-expandable polymer microsphere has a capsule shape having a hollow core and a shell, and a liquid having a boiling point lower than the softening temperature of the shell is encapsulated in the hollow core for foaming.

[0106] The liquid contained in the hollow space of the above heat-expandable polymer microspheres may be a hydrocarbon, for example, n-butane, isobutane, n-pentane, neopentane, isopentane, hexane, isohexane, heptane, octane, cyclopentane, cyclopentene, 1-pentene, 1-hexene, etc., and a hydrocarbon having a boiling point of less than 60°C at atmospheric pressure is preferable. For example, the liquid contained in the hollow space may be isobutane.

[0107] The shell of the above heat-expandable polymer microspheres may include an acrylic copolymer such as an acrylonitrile copolymer.

[0108] The above heat-expandable polymer microspheres are in the form of a general powder at room temperature, but when exposed to high temperatures, the liquid contained in the hollow portion of the heat-expandable polymer microspheres vaporizes, expanding the capsules and allowing them to be used as a foaming agent.

[0109] The above heat-expandable polymer microspheres generally expand at about 150 to 200°C and expand in volume by about 50 to 100 times their initial size.

[0110] For example, the above heat-expandable polymer microspheres can be expanded and the expanded polymer microspheres can be used.

[0111]

[0112] Based on 100 parts by weight of the (meth)acrylate copolymer, the glass microspheres may be included in an amount of 0.1 to 5 parts by weight, or 1 to 2 parts by weight; and the polymer microspheres may be included in an amount of 0.01 to 5 parts by weight, or 0.1 to 1.5 parts by weight.

[0113] In the above range, pores can be formed in an appropriate range inside the elastic sheet.

[0114]

[0115] D50 particle size of additive

[0116] The D50 particle size of the additives other than the above flame retardant may be from 300 nm to 20 μm, but is not limited thereto.

[0117]

[0118] Properties of elastic sheets

[0119] The above elastic sheet can exhibit excellent compressive strength, stress relaxation rate, recovery rate, and thermal conductivity.

[0120]

[0121] Compressive strength

[0122] Hereinafter, CFD (Compression Force Deflection) n% means the compressive strength measured according to ASTM D3574 at the point compressed to (100-n)% of the original thickness.

[0123] When the elastic sheet is in the form of foam, CFD 40% may be 0.5 to 3 MPa, or 2 to 2.5 MPa.

[0124] When the above elastic sheet is in the form of a dense layer, CFD 40% may be 0.5 to 4 MPa, or 2.5 to 3 MPa.

[0125]

[0126] An example of measuring CFD (Compression Force Deflection) n% is as follows.

[0127] An elastic sheet is manufactured into a specimen measuring 2 cm x 2 cm in length x width, and compression is performed at a compression ratio of 0.6 mm / min (10 μm / sec) using a compression tester with a spherical jig having a diameter of 10 mm.

[0128] For elastic sheet specimens, CFD n% is measured using a UTM (manufacturer: Shimadzu Scientific Korea Corp) according to ASTM D3574 at the point where the specimen is compressed to (100-n)% of the initial thickness after pressurization.

[0129]

[0130] Stress relaxation rate

[0131] When the elastic sheet is in the form of foam, the stress relaxation rate according to the following equation 1 may be 5 to 20%, 7 to 15%, or 7.5 to 8.5%.

[0132] When the above elastic sheet is in the form of a dense layer, the stress relaxation rate according to the following equation 1 may be 5 to 20%, 7 to 15%, or 5.5 to 6.5%.

[0133] [Formula 1]

[0134] Stress relaxation rate = 100*(Stress after 60 seconds when compressed to 40% of the original thickness) / (Initial stress when compressed to 40% of the original thickness)

[0135]

[0136] Examples of stress relaxation rate measurements are as follows.

[0137] An elastic sheet is manufactured into a specimen measuring 2 cm x 2 cm in length x width, and compression is performed at a compression ratio of 0.6 mm / min (10 μm / sec) using a compression tester with a spherical jig having a diameter of 10 mm.

[0138] The initial stress is measured at the point where the elastic sheet specimen is compressed to 40% of its initial thickness by applying pressure. In addition, the stress is measured for the elastic sheet specimen 60 seconds after the point where the elastic sheet specimen is compressed to 40% of its initial thickness. Here, the stress at each point is measured using a TA (Texture analyzer, manufacturer: stable micro systems).

[0139] The stress relaxation rate is obtained by substituting the stress measurement values ​​at each point in time into Equation 1 above.

[0140]

[0141] Recovery rate

[0142] When the elastic sheet is in the form of foam, the recovery rate according to the following formula 2 may be 60 to 95%, 65 to 90%, or 75 to 80%.

[0143] When the elastic sheet is in the form of a dense layer, the recovery rate according to the following equation 2 may be 60 to 98%, 70 to 95%, or 85 to 90%.

[0144] [Formula 2]

[0145] Recovery rate = 100*(Stress when restored to 60% of the original thickness after compression to 40% of the original thickness) / (Initial stress when restored to 60% of the original thickness after compression)

[0146]

[0147] Examples of measuring the recovery rate are as follows.

[0148] An elastic sheet is manufactured into a specimen measuring 2 cm x 2 cm in length x width, and compression is performed at a compression ratio of 0.6 mm / min (10 μm / sec) using a compression tester with a spherical jig having a diameter of 10 mm.

[0149] The elastic sheet specimen is compressed to 60% of its original thickness, and the initial stress is measured at that point. In addition, the stress is measured at that point when the elastic sheet specimen, compressed to 40% of its original thickness, is restored to 60% of its original thickness. Here, the stress at each point is measured using a TA (Texture analyzer, manufacturer: stable micro systems).

[0150] The stress measurement values ​​at each point in time are substituted into Equation 2 to obtain the recovery rate.

[0151]

[0152] thermal conductivity

[0153] When the elastic sheet is in the form of foam, the vertical thermal conductivity of the elastic sheet may be 0.3 to 2 W / Mk, or 0.3 to 1 W / Mk; and the horizontal thermal conductivity of the elastic sheet may be 1.5 to 5 W / mK, or 2 to 4 W / Mk.

[0154] When the elastic sheet is in the form of a dense layer, the vertical thermal conductivity of the elastic sheet may be 0.5 to 2 W / mK, or 0.8 to 1.5 W / mK; and the horizontal thermal conductivity of the elastic sheet may be 3 to 15 W / mK, or 6 to 9 W / mK.

[0155]

[0156] Examples of thermal conductivity measurements are as follows.

[0157] The elastic sheet is manufactured into a specimen with a size of 2 cm x 2 cm in length x width, and the thermal conductivity in the horizontal direction is measured using TPS2200 (manufacturer: Hot Disk) according to ISO22007-2, and the thermal conductivity in the vertical direction is measured using TIM-1300 (manufacturer: Analysis Tech) according to ASTM5470.

[0158]

[0159] Thickness of elastic sheet

[0160] The thickness of the above elastic sheet may be 100 ㎛ to 800 ㎛, 100 ㎛ to 600 ㎛, or 120 ㎛ to 200 ㎛. Within this thickness range, the elastic sheet can sufficiently alleviate stress due to pressure and stress due to thickness change during charging and discharging, and can exhibit excellent restoring force.

[0161] The thickness of the above elastic sheet can be measured using a thickness measuring device.

[0162]

[0163] Structure of elastic sheet

[0164] The above elastic sheet may have a single-layer or multi-layer structure, and in the case of a multi-layer structure, each layer may be made of the same material or different materials, and may be designed to have different moduli for each sheet.

[0165] The above elastic sheet may further include a protective film or coating layer on one side.

[0166]

[0167] Method for manufacturing elastic sheets

[0168] The above elastic sheet can be manufactured by a series of processes including polymerizing a monomer mixture constituting the (meth)acrylate copolymer in the presence of an initiator to produce a (meth)acrylate copolymer; mixing the (meth)acrylate copolymer with aluminum hydroxide and inorganic nanotubes, and optionally adding the additive, to produce an elastic sheet composition; coating the elastic sheet composition on a release film and irradiating it with light or heat; and then peeling off the elastic sheet formed on the release film.

[0169]

[0170] (all-solid-state battery)

[0171] In another embodiment, an all-solid-state battery is provided, comprising the elastic sheet; and an electrode assembly, wherein the electrode assembly includes a positive electrode; a negative electrode; and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and the elastic sheet is positioned on the outside of at least one of the positive electrode and the negative electrode.

[0172] 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.

[0173]

[0174] Hereinafter, an all-solid-state battery according to an embodiment is described in detail.

[0175]

[0176] The above all-solid-state battery may also be expressed as an all-solid-state secondary battery or an all-solid-state lithium secondary battery.

[0177] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one 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 active material 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. 1 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.

[0178] An all-solid-state battery according to one embodiment can be manufactured by sequentially stacking a positive electrode, a solid electrolyte, and a negative electrode to prepare a laminate, and then pressurizing the laminate.

[0179] The pressurization may be performed at a temperature of, for example, 25°C to 90°C, and at a pressure of 550 MPa or less, or 500 MPa or less, for example, 400 MPa to 500 MPa. The pressurization may be, for example, an isostatic press, a roll press, or a plate press.

[0180] The above-mentioned all-solid-state battery may be a unit battery 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 battery is repeated.

[0181] The shape of the above-mentioned all-solid-state 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 battery can be applied to medium- to large-sized batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be applied to energy storage systems (ESS) that require a large amount of power storage, and can also be applied to electric bicycles or power tools, etc.

[0182]

[0183] positive electrode active material

[0184] A compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) can be used as a cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0185] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, or a combination thereof.

[0186] As an example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 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); Li a NiG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); Li a FePO4(0.90≤a≤1.8).

[0187] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0188] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less, based on 100 mol% of metals excluding lithium in the lithium transition metal composite oxide. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0189] The cathode active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 11, a lithium cobalt-based oxide represented by the following chemical formula 12, a lithium iron phosphate-based compound represented by the following chemical formula 13, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 14, or a combination thereof.

[0190] [Chemical Formula 11]

[0191] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0192] In the above chemical formula 11, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0193] In the above chemical formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0194] [Chemical Formula 12]

[0195] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0196] In the above chemical formula 12, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0197] [Chemical Formula 13]

[0198] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0199] In the above chemical formula 13, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0200] [Chemical Formula 14]

[0201] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0202] In the above chemical formula 14, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0203] The average particle diameter (D50) 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 diameter (D50) of 1 μm to 9 μm and large particles having an average particle diameter (D50) of 10 μm to 25 μm. A positive electrode active material having such a particle diameter range can be harmoniously mixed with other components within a positive electrode active material layer and can realize high capacity and high energy density. Here, the average particle diameter may be obtained by selecting 20 or so random particles from a scanning electron microscope image of the positive electrode active material, measuring their particle diameters (diameter, major axis, or major axis length), obtaining a particle size distribution, and then taking the diameter (D50) of particles having a cumulative volume of 50% by volume from the particle size distribution as the average particle diameter.

[0204] 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 particle. In addition, the above-mentioned positive electrode active material may be spherical or nearly spherical in shape, or may be polyhedral or irregular in shape.

[0205] Meanwhile, the positive electrode active material may include a buffer layer on the particle surface. The buffer layer may be expressed as a coating layer, a protective layer, etc., and may play a role in lowering the interfacial resistance between the positive electrode active material and the sulfide-based solid electrolyte particles. For example, the buffer layer may include a lithium-metal-oxide, wherein the metal may 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. The lithium-metal-oxide is excellent in lowering the interfacial resistance between the positive electrode active material and the solid electrolyte particles while improving the performance of the positive electrode active material by facilitating the movement of lithium ions and electron conduction.

[0206]

[0207] anode

[0208] A positive electrode for an all-solid-state battery includes a current collector and a positive electrode active material layer positioned on the current collector, wherein the positive electrode active material layer includes a positive electrode active material and may optionally include a solid electrolyte, a binder, and / or a conductive material.

[0209] For example, the anode may further include an additive that can act as a sacrificial anode.

[0210] The content of the positive electrode active material may be 90 wt% to 99.5 wt% with respect to 100 wt% of the positive electrode active material layer, and the contents of the binder and conductive material may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0211] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector. Representative examples of the binder include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0212] 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 nanotube; 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 mixtures thereof.

[0213] The positive electrode active material layer may optionally further include a solid electrolyte. The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof, and a detailed description thereof will be provided later in the section on the solid electrolyte layer.

[0214] With respect to 100 wt% 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%.

[0215] In the positive electrode active material layer, the positive electrode active material may be comprised in an amount of 65 to 99 wt% and the solid electrolyte in an amount of 1 to 35 wt%, based on 100 wt% of the total of the positive electrode active material and the solid electrolyte, for example, the positive electrode active material may be comprised in an amount of 80 to 90 wt% and the solid electrolyte in an amount of 10 to 20 wt%. When the solid electrolyte is comprised in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state secondary battery can be improved without reducing the capacity.

[0216] Al may be used as the above current collector, but is not limited thereto.

[0217]

[0218] Negative active material

[0219] The negative electrode active material includes 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.

[0220] 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.

[0221] As the above lithium metal alloy, an alloy of lithium and a metal 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.

[0222] 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 may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein Q is selected from alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements (excluding Si), Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0223] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0224] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0225] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0226]

[0227] cathode

[0228] An anode for an all-solid-state battery may include, for example, a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0229] For example, the negative electrode active material layer may include 90 to 99 wt% of the negative electrode active material, 0.5 to 5 wt% of the binder, and 0 to 5 wt% of the conductive material.

[0230] 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 be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0231] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0232] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0233] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0234] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0235] 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. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, 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.

[0236] 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.

[0237]

[0238] precipitation cathode

[0239] Meanwhile, as an example, the above-mentioned all-solid-state battery negative electrode may be a precipitation-type negative electrode. The precipitation-type negative electrode refers to a negative electrode that does not have a negative electrode active material when the battery is assembled, but in which lithium metal or the like is precipitated when the battery is charged, and this acts as a negative electrode active material.

[0240] Fig. 2 is a schematic cross-sectional view of an all-solid-state battery including a precipitation-type negative electrode. Referring to Fig. 2, the precipitation-type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) positioned on the current collector. An all-solid-state battery including such a precipitation-type negative electrode (400') starts initial charging in a state in which no negative electrode active material is present, and upon charging, high-density lithium metal or the like is precipitated between the current collector (401) and the negative electrode coating layer (405) to form a lithium metal layer (404), which may function as a negative electrode active material. Accordingly, in an all-solid-state battery that has been charged at least once, the precipitation-type negative electrode (400') may include a current collector (401), a lithium metal layer (404) positioned on the current collector, and a negative electrode coating layer (405) positioned on the metal layer. The above lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and may be referred to as a metal layer or a negative electrode active material layer.

[0241] The above cathode coating layer (405) may include a metal and / or carbon material that acts as a catalyst.

[0242] The metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one kind of these or may be composed of several kinds of alloys. The average particle diameter (D50) of the metal may be about 4 μm or less, and may be, for example, 10 nm to 4 μm, 10 nm to 2 μm, or 10 nm to 1 μm.

[0243] The carbon material may be, for example, crystalline carbon, non-graphitic carbon, or a combination thereof. The crystalline carbon may be, for example, at least one selected from natural graphite, artificial graphite, mesophase carbon microbeads, and combinations thereof. The non-graphitic carbon may be at least one selected from carbon black, activated carbon, acetylene black, Denka black, Ketjen black, furnace black, graphene, and combinations thereof.

[0244] When the above-described negative electrode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 1:2, 1:10 to 2:1, 5:1 to 1:1, or 4:1 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-described negative electrode coating layer (405) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0245] The above cathode coating layer (405) may further include a binder, and the binder may be, for example, a conductive binder. In addition, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0246] The thickness of the negative electrode coating layer (405) may be, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. In addition, the thickness of the negative electrode coating layer (405) may be 50% or less, 20% or less, or 5% or less of the thickness of the positive electrode active material layer. If the thickness of the negative electrode coating layer (405) is too thin, it may be collapsed by the lithium metal layer (404), and if the thickness is too thick, the density of the all-solid-state battery may decrease and the internal resistance may increase.

[0247] The above-described precipitated negative electrode (400') may further include, for example, a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one type thereof or may be composed of multiple types of alloys. The thin film may further flatten the precipitated form of the lithium metal layer (404) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 800 nm, or 100 nm to 500 nm.

[0248] The lithium metal layer (404) may include lithium metal or a lithium alloy. 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, or a Li-Si alloy.

[0249] The thickness of the lithium metal layer (404) may be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer (404) is too thin, it may be difficult to perform the role of a lithium storage, and if it is too thick, the battery volume may increase and performance may deteriorate.

[0250] When such a precipitation-type cathode is applied, the cathode coating layer (405) can play a role in protecting the lithium metal layer (404) and suppressing the precipitation growth of lithium deadlight. Accordingly, short-circuiting and capacity reduction of the all-solid-state battery can be suppressed, and the life characteristics can be improved.

[0251]

[0252] solid electrolyte layer

[0253] The solid electrolyte layer contains a solid electrolyte.

[0254] The above solid electrolyte may be a type of inorganic solid electrolyte, and may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof.

[0255] Sulfide-based solid electrolyte

[0256] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5--LiX (where 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, n are integers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or a combination thereof.

[0257] A sulfide-based solid electrolyte can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or 50:50 to 80:20, and optionally heat-treating them. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. The ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0258] Methods for mixing sulfur-containing raw materials for producing sulfide-based solid electrolytes include mechanical milling or the solution method. Mechanical milling involves placing raw materials in a ball mill reactor and vigorously stirring them to finely atomize and mix them. Using the solution method, the 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 produced by mixing sulfur-containing raw materials and heat-treating them twice or more, resulting in a sulfide-based solid electrolyte with high ionic conductivity and robustness.

[0259] According to one embodiment, sulfide-based solid electrolyte particles can be manufactured through, for example, a first heat treatment in which sulfur-containing raw materials are mixed and calcined at 120°C to 350°C, and a second heat treatment in which the first heat treatment result is mixed and calcined at 350°C to 800°C. The first heat treatment and the second heat treatment can each be performed in an inert gas or nitrogen atmosphere. The first heat treatment can be performed for 1 to 10 hours, and the second heat treatment can be performed for 5 to 20 hours. The first heat treatment can have the effect of milling small raw materials, and the second heat treatment can synthesize the final solid electrolyte. Through two or more such heat treatments, a high-performance sulfide-based solid electrolyte with high ionic conductivity and robustness can be obtained, and such a solid electrolyte can be said to be suitable for mass production. The temperature of the first heat treatment may be, for example, 150°C to 330°C, or 200°C to 300°C, and the temperature of the second heat treatment may be, for example, 380°C to 700°C, or 400°C to 600°C.

[0260] For example, the sulfide-based solid electrolyte particles may include argyrodite-type sulfides. The argyrodite-type sulfide-based solid electrolyte particles may have an ionic conductivity of 10, which is the ionic conductivity of a typical liquid electrolyte at room temperature. -4 10 inland -2 It has a high ionic conductivity approaching the S / cm range, can form a close bond between a positive electrode active material and a solid electrolyte without causing a decrease in ionic conductivity, and further can form a close interface between an electrode layer and a solid electrolyte layer. An all-solid-state secondary battery including this can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0261] The argyrodite-type sulfide-based solid electrolyte particles may include, for example, a compound represented by the chemical formula 21 below.

[0262] [Chemical Formula 21]

[0263] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0264] In the above chemical formula 21, 4≤a≤8, and M 1 is Mg, Cu, Ag, or a combination thereof, and 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, and 1.5≤n≤5, 3≤f≤12, 0≤g<2, and X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0265] For example, in chemical formula 21, a halide element (X) may be included as an essential element, in which case 0 <h≤2로 표시될 수 있다. 일 예로 화학식 21에 M 1 Elements may be required, in which case 0 <b<0.5로 표시될 수 있다. 화학식 21에서 M 3 can be understood as an element substituted in place of P and 0 <e<1일 수 있다. 화학식 21에서 M 4 is substituted in the S position, for example, 0 <g<2일 수 있으며 S의 비율인 f는 예를 들어 3≤f≤7일 수 있다. M 4 Go SO n If SO n It can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, and can be, for example, SO4.

[0266] For example, in chemical formula 21, a+b+c+h=7, d+e=1, and f+g+h=6.

[0267] As a specific example, argyrodite-type sulfide-based solid electrolyte particles include Li3PS4 and Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , 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 Cu0.06 )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.

[0268] An argyrodite-type sulfide-based solid electrolyte can be manufactured, for example, by mixing lithium sulfide and phosphorus sulfide, and optionally, lithium halide. After mixing these, a heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps. Here, manufacturing an argyrodite-type sulfide-based solid electrolyte may include, for example, a first heat treatment of mixing raw materials and calcining at 120°C to 350°C, and a second heat treatment of mixing the resultant of the first heat treatment again and calcining at 350°C to 800°C.

[0269] The average particle size (D50) of the sulfide-based solid electrolyte particles may be, for example, 0.1 ㎛ to 5.0 ㎛ or 0.1 ㎛ to 3.0 ㎛, and may be small particles of 0.1 ㎛ to 1.9 ㎛ or large particles of 2.0 ㎛ to 5.0 ㎛. The sulfide-based solid electrolyte particles may be a mixture of small particles having an average particle size of 0.1 ㎛ to 1.9 ㎛ and large particles having an average particle size of 2.0 ㎛ to 5.0 ㎛. The average particle size of the sulfide-based solid electrolyte particles may be measured from an electron microscope image, and for example, a particle size distribution may be obtained by measuring the size (diameter or major axis length) of about 20 particles in a scanning electron microscope image, and D50 may be calculated from this.

[0270]

[0271] Oxide-based solid electrolyte

[0272] Oxide-based solid electrolytes include, 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 y O3(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 Siy 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 mixtures thereof.

[0273]

[0274] Halide-based solid electrolyte

[0275] The solid electrolyte layer may further include, for example, a halide-based solid electrolyte. The halide-based solid electrolyte contains a halogen element as a main component, and may mean that the ratio of the halide element to all elements constituting the solid electrolyte is 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. For example, the halide-based solid electrolyte may not contain a sulfur element.

[0276] The halide-based solid electrolyte may contain lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may be Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof. The halogen element may be F, Cl, Br, I, or a combination thereof, and may be Cl, Br, or a combination thereof. The halide-based solid electrolyte may contain, for example, Li aM1X6 (M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof, X is F, Cl, Br, I, or a combination thereof, and 2≤a≤3) can be represented. The halide-based solid electrolyte may be, for example, Li2ZrCl6, Li 2.7 Y 0.7 Zr 0.3 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 In 0.5 Zr 0.5 Cl6, Li2In 0.5 Zr 0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6 Cl6, or combinations thereof, but is not limited thereto.

[0277]

[0278] bookbinder

[0279] The solid electrolyte layer may further include a binder. Binders include, for example, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluoroelastomer, natural rubber, polydimethylsiloxane, polyethylene oxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polyamideimide, polyimide, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane resin, and the like. copolymers, or combinations thereof.

[0280] The binder may be included in an amount of 0.1 wt% to 3 wt% based on 100 wt% of the solid electrolyte layer, for example, 0.5 wt% to 2 wt%, or 0.5 wt% to 1.5 wt%. When the binder is included in the above range, the components within the solid electrolyte layer can be well combined without lowering the ionic conductivity of the solid electrolyte, thereby improving the durability and reliability of the battery.

[0281]

[0282] Other ingredients

[0283] The solid electrolyte layer may optionally further comprise an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0284] 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.

[0285] The lithium salt may be applied without limitation on type, and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or a combination thereof.

[0286] For example, the lithium salt may be an imide-based lithium salt such as LiTFSI, LiFSI, LiBETI, or a combination thereof. The imide-based lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0287] Ionic liquids are salts or molten salts that are composed only of ions and are liquid at room temperature, with a melting point below room temperature.

[0288] The ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, trizolium, 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.

[0289] 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.

[0290] In the solid electrolyte layer, the weight ratio of the solid electrolyte to 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.

[0291]

[0292] A lithium secondary battery according to one embodiment of the present invention can be applied to automobiles, mobile phones, and / or various types of electrical devices, but the present invention is not limited thereto.

[0293]

[0294] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0295]

[0296] Manufacturing example: Manufacturing of acrylate copolymer

[0297] 100 parts by weight of a monomer mixture containing 2-ethylhexyl acrylate (2-EHA, manufacturer: LG Chemical), isobornyl acrylate (IBOA, manufacturer: Osaka organic chemical), and 4-hydroxybutyl acrylate (4-HBA, manufacturer: Osaka Organic Chemical) in a weight ratio of 50:15:35, and 0.35 parts by weight of 1,2-diphenyl-2,2-dimethoxyethanone (trade name: igacure651, manufacturer: Ciba) as an initiator was added, and the dissolved oxygen in the reactor was exchanged with nitrogen gas, and then the UV intensity was 10 mw / cm 2 The monomer mixture was partially polymerized by irradiating it with ultraviolet rays for several minutes using a lamp to produce an acrylate copolymer (Mw=1,300,000 g / mol, Mw / Mn=1.7).

[0298]

[0299] (elastic sheet in foam form)

[0300] Example 1

[0301] (1) Manufacturing of elastic sheets

[0302] Based on 100 parts by weight of the acrylate copolymer of the above manufacturing example, 0.1 part by weight of 1,6-hexanediol diacrylate as a crosslinking agent, 200 parts by weight of aluminum hydroxide, 0.1 part by weight of boehmite nanotubes (Bohemite, aspect ratio: 40, manufacturer: Aramis) as inorganic nanotubes, 10 parts by weight of aluminum diethylphosphinate (ADP, OMP-900; manufacturer: Universal Chemtech) as a flame retardant, 0.5 part by weight of acrylonitrile microspheres (trade name: Expancel 920DET40 d25, D50: 40 ㎛, manufacturer: Nouryon) as heat-expanded polymer microspheres, and 1.5 parts by weight of glass bubbles (trade name: K-1, manufacturer: 3M) as glass microspheres were mixed to manufacture an elastic sheet composition.

[0303] The above elastic sheet composition is applied on a polyethylene terephthalate (PET) film, which is a release film, and exposed to 2000 mJ / cm of ultraviolet light. 2 By examining the amount of light, an elastic sheet was manufactured by bonding it to a release film. Thereafter, the release film was removed to obtain an elastic sheet.

[0304] (2) Manufacturing of the anode

[0305] 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.

[0306] 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.

[0307] (3) Manufacturing of solid electrolyte layer

[0308] An acrylic binder (SX-A334, Zeon) was dissolved in an isobutyl isobutyrate (IBIB) solvent. An argyrodite-type solid electrolyte, Li6PS5Cl (D50=3㎛), was added to the binder solution, which was stirred in a sinky mixer to adjust the viscosity to an appropriate level. 2 mm zirconia balls were added and stirred again in the sinky mixer to prepare a slurry. In the prepared slurry, the content of the solid electrolyte was 98.5 wt%, and the content of the binder was 1.5 wt%.

[0309] The above slurry was applied using a bar coater onto a polyethylene terephthalate (PET) film, which is a release film, and dried at room temperature (25°C). Then, the release film was removed to obtain a solid electrolyte layer.

[0310] (4) Manufacturing of cathode

[0311] 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.

[0312] 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.

[0313] (5) Manufacturing of all-solid-state batteries

[0314] 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.

[0315] 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.

[0316] In a pressurized state, the thickness of the positive electrode active material layer was about 100 μm, the thickness of the negative electrode coating 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.

[0317]

[0318] Example 2

[0319] An elastic sheet and an all-solid-state battery are manufactured in the same manner as Example 1, except that 100 parts by weight of aluminum hydroxide is used based on 100 parts by weight of the acrylate copolymer of the above manufacturing example.

[0320]

[0321] Example 3

[0322] An elastic sheet and an all-solid-state battery are manufactured in the same manner as Example 1, except that 100 parts by weight of aluminum hydroxide is used based on 100 parts by weight of the acrylate copolymer of the above manufacturing example and that the flame retardant is not used.

[0323]

[0324] Comparative Example 1

[0325] An elastic sheet and an all-solid-state battery are manufactured in the same manner as Example 1, except that 100 parts by weight of aluminum hydroxide is used based on 100 parts by weight of the acrylate copolymer of the above manufacturing example; and the inorganic nanotubes and the flame retardant are not used.

[0326]

[0327] Comparative Example 2

[0328] An elastic sheet and an all-solid-state battery are manufactured in the same manner as in Example 1, except that the aluminum hydroxide, the inorganic nanotubes, and the flame retardant are not used.

[0329]

[0330] Evaluation Example 1: Evaluation of mechanical properties of elastic sheets

[0331] The elastic sheets of Examples 1 to 3 and Comparative Examples 1 and 2 were manufactured into specimens measuring 2 cm x 2 cm in length x width, and compressed at a compression rate of 0.6 mm / min (10 μm / sec) using a compression tester with a spherical jig having a diameter of 10 mm, and the compressive strength, stress relaxation rate, and recovery rate were evaluated as follows. The evaluation results are shown in Table 1 below.

[0332] (1) Compressive strength

[0333] For the above elastic sheet specimen, CFD 40% was measured using a UTM (manufacturer: Shimadzu Scientific Korea Corp) according to ASTM D3574 at the time of compression to 60% of the initial thickness after pressurization.

[0334] (2) Stress relaxation rate

[0335] The initial stress was measured when the elastic sheet specimen was compressed to 40% of its initial thickness. In addition, the stress was measured for the elastic sheet specimen 60 seconds after the elastic sheet specimen was compressed to 40% of its initial thickness. Here, the stress at each point in time was measured using a TA (Texture analyzer, manufacturer: stable micro systems).

[0336] The stress relaxation rate was calculated according to Equation 1 below.

[0337] [Formula 1]

[0338] Stress relaxation rate = 100*(Stress after 60 seconds when compressed to 40% of the original thickness) / (Initial stress when compressed to 40% of the original thickness)

[0339] (3) Recovery rate

[0340] The elastic sheet specimen was compressed to 60% of its original thickness, and the initial stress was measured at that point. In addition, the stress was measured at that point when the elastic sheet specimen, compressed to 40% of its original thickness, was restored to 60% of its original thickness. Here, the stress at each point was measured using a TA (Texture analyzer, manufacturer: stable micro systems).

[0341] The recovery rate was calculated according to Equation 2 below.

[0342] [Formula 2]

[0343] Recovery rate = 100*(Stress when restored to 60% of the original thickness after compression to 40% of the original thickness) / (Initial stress when restored to 60% of the original thickness after compression)

[0344]

[0345] Evaluation Example 2: Evaluation of thermal properties of elastic sheets

[0346] The elastic sheets of Examples 1 to 3 and Comparative Examples 1 and 2 were manufactured into specimens measuring 2 cm x 2 cm in length x width, and the thermal conductivity and flame retardancy grades were evaluated as follows. The evaluation results are shown in Table 1 below.

[0347] (1) Thermal conductivity

[0348] For elastic sheet specimens, the thermal conductivity in the horizontal direction was measured using TPS2200 (manufacturer: Hot Disk) according to ISO22007-2, and the thermal conductivity in the vertical direction was measured using TIM-1300 (manufacturer: Analysis Tech) according to ASTM5470.

[0349] (2) Flame retardant grade

[0350] For the elastic sheet specimens, a combustion test was conducted in accordance with the VTM test described in the UL standard (UL94 “Method for Combustion Test of Plastic Materials for Components of Equipment”).

[0351]

[0352] Evaluation Example 3: Evaluation of Electrochemical Characteristics of All-Solid-State Batteries

[0353] For the all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1 and 2, the coulombic efficiency and lifespan were evaluated using the following methods. The evaluation results are shown in Table 1 below.

[0354] (1) Coulomb efficiency

[0355] For the all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1 and 2, initial charging and discharging was performed by charging to an upper limit voltage of 4.25 V at a constant current of 0.1 C at 45°C and then discharging to an end voltage of 2.5 V at 0.1 C.

[0356] [Formula 3]

[0357] Coulomb efficiency = 100 * (initial discharge capacity / initial charge capacity)

[0358] (2) Lifespan

[0359] After the above Coulomb efficiency measurement, charging at 0.33C and discharging at 0.33C in a voltage range of 2.5 V to 4.25 V at 45°C were repeated more than 300 times, and the number of cycles at which the discharge capacity retention rate for the initial discharge dropped to 80% was evaluated.

[0360]

[0361] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Elastic sheet composition (parts by weight) Acrylate copolymer 100 100 100 100 100 Crosslinking agent 0.10.10.10.10.1 Aluminum hydroxide 200 100 100 100 - Inorganic nanotube 0.10.10.1 - Flame retardant 10 10 - Polymer microsphere 0.5 0.5 0.5 0.5 0.5 Glass microsphere 1.5 1.5 1.5 1.5 1.5 Inorganic particle ----- Properties of elastic sheet Compressive strength @ CFD 40% (MPa) 2.4 2.2 2.12 11.8 Stress relaxation rate (%) 7.5 8.3 8.2 8.2 10.3 Recovery rate (%) 79 76 76 76 73 Heat Conductivity (W / mK) Horizontal 3.6132.1322.9351.450.795 Vertical 0.6150.3770.4050.2090.122 UL94VTM-0VTM-0VTM-0VTM-0NG Electrochemical Characteristics of All-Solid-State Battery Coulombic Efficiency (%) 9392939289 Lifespan (cycles) 300300300130270

[0362]

[0363] (elastic sheet in the form of a dense layer)

[0364] Example 4

[0365] (1) Manufacturing of elastic sheets

[0366] Based on 100 parts by weight of the acrylate copolymer of the above manufacturing example, 0.1 parts by weight of 1,6-hexanediol diacrylate as a crosslinking agent, 200 parts by weight of aluminum hydroxide, 0.1 parts by weight of boehmite nanotubes (Bohemite, aspect ratio: 40, manufacturer: Aramis) as inorganic nanotubes, 10 parts by weight of aluminum diethylphosphinate (ADP, OMP-900; manufacturer: Universal Chemtech) as a flame retardant, and 50 parts by weight of spherical boehmite (D50: 300 nm) as inorganic particles were mixed to manufacture an elastic sheet composition.

[0367] The above elastic sheet composition is applied on a polyethylene terephthalate (PET) film, which is a release film, and exposed to 2000 mJ / cm of ultraviolet light. 2By examining the amount of light, an elastic sheet was manufactured by bonding it to a release film. Thereafter, the release film was removed to obtain an elastic sheet.

[0368] (2) Manufacturing of all-solid-state batteries

[0369] An all-solid-state battery is manufactured in the same manner as in Example 1, except that the above elastic sheet is used.

[0370]

[0371] Example 5

[0372] An elastic sheet and an all-solid-state battery are manufactured in the same manner as in Example 4, except that the above-mentioned inorganic particles are not used.

[0373]

[0374] Example 6

[0375] An elastic sheet and an all-solid-state battery are manufactured in the same manner as in Example 4, except that the flame retardant and the inorganic particles are not used.

[0376]

[0377] Example 7

[0378] An elastic sheet and an all-solid-state battery are manufactured in the same manner as Example 4, except that 0.2 parts by weight of the above-mentioned inorganic nanotubes are used and the above-mentioned flame retardant and the above-mentioned inorganic particles are not used.

[0379]

[0380] Comparative Example 3

[0381] An elastic sheet and an all-solid-state battery are manufactured in the same manner as in Example 4, except that the inorganic nanotubes, flame retardant, and inorganic particles are not used.

[0382]

[0383] Comparative Example 4

[0384] An elastic sheet and an all-solid-state battery are manufactured in the same manner as in Example 4, except that the aluminum hydroxide, the inorganic nanotubes, the flame retardant, and the inorganic particles are not used.

[0385]

[0386] Evaluation Example 4: Evaluation of mechanical properties of elastic sheets

[0387] For the elastic sheets of Examples 4 to 7 and Comparative Examples 3 and 4, the compressive strength, stress relaxation rate, and recovery rate were evaluated in the same manner as in Evaluation Example 1. The evaluation results are shown in Table 2 below.

[0388]

[0389] Evaluation Example 5: Evaluation of thermal properties of elastic sheets

[0390] For the elastic sheets of Examples 4 to 7 and Comparative Examples 3 and 4, thermal conductivity and flame retardancy grades were evaluated in the same manner as in Evaluation Example 2. The evaluation results are shown in Table 2 below.

[0391]

[0392] Evaluation Example 6: Evaluation of Electrochemical Characteristics of All-Solid-State Batteries

[0393] For the all-solid-state batteries of Examples 4 to 7 and Comparative Examples 3 and 4, the coulombic efficiency and lifespan were evaluated using the same method as in Evaluation Example 3. The evaluation results are shown in Table 2 below.

[0394]

[0395] Example 4 Example 5 Example 6 Example 7 Comparative Example 3 Comparative Example 4 Elastic sheet composition (parts by weight) Acrylate copolymer 100 100 100 100 100 100 Crosslinking agent 0.10.10.10.10.10.1 Aluminum hydroxide 200 200 200 200 200 - Inorganic nanotube 0.10.10.10.2 - Flame retardant 10 10 ---- Polymer microspheres ---- Glass microspheres ---- Inorganic particles 50 ---- Properties of elastic sheet Compressive strength @ CFD 40% (MPa) 2.9 2.7 2.6 2.6 2.6 2.0 Stress relaxation rate (%) 5.8 5.8 6.3 6.3 6.5 6.8 Recovery rate (%) 89 88 85 85 7 57 3 Heat Conductivity (W / mK) Horizontal 8.16.26.5 29.15 22.15 0.622 Vertical 1.02 0.81 80.84 81.35 0.40 10.122 Flame retardant rating UL94 VTM-0 VTM-0 VTM-0 VTM-0 VTM-0 NG Electrochemical characteristics of all-solid-state batteries Coulombic efficiency (%) 9 4 9 4 9 3 9 2 9 1 9 Lifespan (cycle count) 300 300 300 300 9 5 8 5

[0396]

[0397] (synthesis)

[0398] In summary of Tables 1 and 2 above, when the shape of the elastic sheet is the same, it can be seen that the elastic sheet (Example) essentially including a (meth)acrylate copolymer; aluminum hydroxide; and inorganic nanotubes exhibits superior compressive strength, stress relaxation rate, recovery rate, thermal conductivity, and flame retardancy compared to the elastic sheet (Comparative Example) from which at least one of the (meth)acrylate copolymer; aluminum hydroxide; and inorganic nanotubes is excluded.

[0399] Furthermore, it can be seen that the elastic sheet of the embodiment having the above-described characteristics improves the life characteristics and Coulomb characteristics of an all-solid-state battery.

[0400] Meanwhile, when the elastic sheet is in the form of a foam, its resilience can be improved, and when the elastic sheet is in the form of a dense layer, its compressive strength and thermal conductivity can be improved. Accordingly, the use of the pore-forming agent can be determined depending on the desired properties.

[0401]

[0402] 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.

[0403]

[0404] [Explanation of symbols]

[0405] 100: All-solid-state battery 200: Cathode

[0406] 201: Cathode current collector 203: Cathode active material layer

[0407] 300: solid electrolyte layer 400: cathode

[0408] 401: Negative current collector 403: Negative active material layer

[0409] 400': Precipitation type cathode 404: Lithium metal layer

[0410] 405: Cathode coating layer 500: Elastic layer

Claims

1. (Meth)acrylate copolymer; aluminum hydroxide; and Containing inorganic nanotubes, Elastic sheet for all-solid-state batteries.

2. In paragraph 1, Based on 100 parts by weight of the above (meth)acrylate copolymer, The above aluminum hydroxide is contained in an amount of 100 to 300 parts by weight, The above inorganic nanotubes are included in an amount of 0.01 to 1 part by weight, Elastic sheet for all-solid-state batteries.

3. In paragraph 1, (Meth)acrylate copolymers are A first structural unit derived from a C1 to C20 linear alkyl (meth)acrylate, A second structural unit derived from a C1 to C20 cyclic alkyl (meth)acrylate, and A third structural unit derived from a C1 to C20 alkyl (meth)acrylate containing a hydroxyl group, Elastic sheet for all-solid-state batteries.

4. In paragraph 3, The above (meth)acrylate copolymer is a copolymer of 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Elastic sheet for all-solid-state batteries.

5. In paragraph 1, The above inorganic nanotubes are, Boehmite nanotubes, alumina nanotubes, boron nitride nanotubes, or a combination thereof, Elastic sheet for all-solid-state batteries.

6. In paragraph 1, The aspect ratio of the above-mentioned inorganic nanotube is 3 or more, Elastic sheet for all-solid-state batteries.

7. In paragraph 1, The above elastic sheet further comprises an additive, The above additives are crosslinking agents, inorganic particles, flame retardants, pore formers, or combinations thereof. Elastic sheet for all-solid-state batteries.

8. In paragraph 7, The above crosslinking agent is a multifunctional (meth)acrylate, Elastic sheet for all-solid-state batteries.

9. In paragraph 7, The above inorganic particles are boehmite, alumina, or a combination thereof. Elastic sheet for all-solid-state batteries.

10. In paragraph 7, The above pore former is an inorganic pore former, an organic pore former, or a combination thereof. Elastic sheet for all-solid-state batteries.

11. In paragraph 1, The D50 particle size of the additives excluding the above flame retardant is 300 nm to 20 μm. Elastic sheet for all-solid-state batteries.

12. In paragraph 1, The above elastic sheet is in the form of foam or dense layer, Elastic sheet for all-solid-state batteries.

13. In paragraph 12, The above elastic sheet is in the form of foam, The CFD 40% compressive strength, measured in accordance with ASTM D3574 at the point compressed to 60% of the original thickness, is 0.5 to 3 MPa, The stress relaxation rate according to the following formula 1 is 5 to 20%, The recovery rate according to the following formula 2 is 60 to 95%, The vertical thermal conductivity of the above elastic sheet is 0.3 to 2 W / mK, The horizontal thermal conductivity of the above elastic sheet is 1.5 to 5 W / mK, Elastic sheets for all-solid-state batteries: [Formula 1] Stress relaxation rate = 100*(Stress after 60 seconds when compressed to 40% of the original thickness) / (Initial stress when compressed to 40% of the original thickness) [Formula 2] Recovery rate = 100*(Stress when restored to 60% of the original thickness after compression to 40% of the original thickness) / (Initial stress when restored to 60% of the original thickness after compression) 14. In paragraph 12, The above elastic sheet is in the form of a dense layer, The CFD 40% compressive strength, measured in accordance with ASTM D3574 at the point compressed to 60% of the original thickness, is 0.5 to 4 MPa, The stress relaxation rate according to the following formula 1 is 5 to 20%, The recovery rate according to the following formula 2 is 60 to 98%. The vertical thermal conductivity of the above elastic sheet is 0.5 to 2 W / mK, The horizontal thermal conductivity of the above elastic sheet is 3 to 15 W / mK, Elastic sheets for all-solid-state batteries: [Formula 1] Stress relaxation rate = 100*(Stress after 60 seconds when compressed to 40% of the original thickness) / (Initial stress when compressed to 40% of the original thickness) [Formula 2] Recovery rate = 100*(Stress when restored to 60% of the original thickness after compression to 40% of the original thickness) / (Initial stress when restored to 60% of the original thickness after compression) 15. An elastic sheet according to any one of claims 1 to 14; and an electrode assembly, The electrode assembly comprises an anode; a cathode; and a solid electrolyte layer positioned between the anode and the cathode, An all-solid-state battery, wherein the elastic sheet is positioned on the outer side of at least one of the positive electrode and the negative electrode.

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