Elastic sheet for all-solid-state rechargeable batteries, and all-solid-state rechargeable batteries

Abstract

The present invention relates to: an elastic sheet for all-solid-state rechargeable batteries, comprising a curable resin and an insulation filler, and having dielectric breakdown strength of 7-15 KV / mm, tensile strength of 3-6 MPa, and elongation of 150% or higher; and all-solid-state rechargeable batteries.

Description

Elastic sheets for all-solid-state secondary batteries and all-solid-state secondary batteries

[0001] It relates to an elastic sheet for an all-solid-state secondary battery and an all-solid-state secondary battery.

[0002] Lithium secondary batteries, which boast high energy density and portability, are primarily used as power sources for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, active research is underway to utilize high-energy-density lithium secondary batteries as power sources for hybrid and electric vehicles, or as power storage devices.

[0003] Commercially available lithium secondary batteries use electrolytes containing flammable organic solvents, posing safety concerns that can lead to explosions or fires in the event of collisions, penetrations, or other problems. Therefore, semi-solid or all-solid-state batteries, which avoid the use of electrolytes, are being proposed. All-solid-state batteries are comprised entirely of solid materials, specifically those that utilize solid electrolytes. These all-solid-state batteries are safe, eliminating the risk of electrolyte leakage and explosion, and offer the advantage of being easy to manufacture in thin forms.

[0004] Provided is an elastic sheet with improved voltage characteristics and mechanical properties, which can prevent fire or explosion by preventing short circuits in batteries in abnormal situations such as penetration or collision, and an all-solid-state secondary battery using the elastic sheet.

[0005] In one embodiment, an elastic sheet for an all-solid-state secondary battery including a curable resin and an insulating filler is provided, wherein the elastic sheet has an insulation breakdown strength of 7 kV / mm to 15 kV / mm, a tensile strength of 3 MPa to 6 MPa, and an elongation of 150% or more.

[0006] In one embodiment, an all-solid-state secondary battery is provided, comprising two or more cell structures including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and the elastic sheet positioned between the cell structures and / or at the outermost surface of the cell structures.

[0007] An elastic sheet according to an embodiment has excellent voltage resistance characteristics and mechanical properties, and can effectively prevent short circuits of a battery in abnormal situations such as penetration or collision, thereby preventing fire and explosion.

[0008] Figures 1 and 2 are cross-sectional views schematically showing an all-solid-state secondary battery according to one embodiment.

[0009] Figure 3 is a graph showing the results of a penetration test on the all-solid-state secondary battery of Example 1, showing temperature changes and voltage changes over time after penetration.

[0010] Below, specific implementation examples are described in detail to facilitate their implementation by those skilled in the art. However, the present invention may be implemented in various different forms and is not limited to the implementation examples described herein.

[0011] 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.

[0012] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0013] 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.

[0014] To clearly illustrate various layers and regions in the drawings, their thicknesses are enlarged, and similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" or "on" another element, this includes not only the case where it is "directly over" the other element, but also the case where there are other elements in between. Conversely, when an element is said to be "directly over" another element, it means that there are no other elements in between.

[0015] “Layer” includes not only shapes formed on the entire surface when observed in a plan view, but also shapes formed on some surfaces.

[0016] The average particle size can be measured by methods well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with transmission electron microscope images or scanning electron microscope images. Alternatively, the average particle size can be obtained by measuring using dynamic light scattering, performing data analysis, counting the number of particles for each particle size range, and calculating from the counted number. Unless otherwise defined, the average particle size is the diameter (D) of the particles in the particle size distribution that have a cumulative volume of 50% by volume. 50 ) can mean. In addition, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of major axis) of about 20 particles randomly in a scanning electron microscope image to obtain a particle size distribution, and the diameter (D) of the particle having a cumulative volume of 50% by volume in the particle size distribution 50 ) may be taken as the average particle diameter.

[0017] “Or” is not interpreted as exclusive, for example, “A or B” is interpreted as including A, B, A+B, etc.

[0018] “Metal” is interpreted as a concept that includes common metals, transition metals, and metalloids (semi-metals).

[0019] elastic sheet

[0020] In one embodiment, an elastic sheet for an all-solid-state secondary battery including a curable resin and an insulating filler is provided, wherein the elastic sheet has an insulation breakdown strength of 7 kV / mm to 15 kV / mm, a tensile strength of 3 MPa to 6 MPa, and an elongation of 150% or more.

[0021] The elastic sheet ensures that pressure is evenly transmitted to the cell structure (or electrode assembly), thereby ensuring good contact between solid components, and also alleviates stress transmitted to the solid electrolyte, etc., and suppresses cracks in the solid electrolyte caused by stress accumulation due to changes in the thickness of the electrode during charging and discharging, thereby buffering changes in the volume of the battery. The elastic sheet may be positioned between the cell structures, or may be positioned on the outermost surface of the cell structures, or on the inner surface of the case.

[0022] All-solid-state secondary batteries utilize solid electrolytes instead of liquid ones, ensuring fire safety. However, if the solid electrolyte is destroyed by penetration or impact, causing the anode and cathode to come into contact and short-circuit, the temperature inside the battery may increase, potentially leading to a fire. Therefore, one embodiment proposes a technology that applies an insulating filler to an elastic sheet to improve insulation breakdown strength and elongation, and to provide appropriate tensile strength, thereby preventing short-circuiting and effectively preventing fire or explosion even if the solid electrolyte is destroyed by penetration or other causes. The elastic sheet according to the embodiment not only exhibits high thermal and electrical safety, but also has excellent mechanical properties such as voltage resistance, chemical resistance, dimensional stability, and elongation. Furthermore, it is economical due to its low material cost, and it does not contain graphite compounds, allowing for free thickness control. All-solid-state secondary batteries utilizing such elastic sheets ensure thermal, electrical, and physical safety, and have enhanced reliability, and can be used in a variety of fields, including electric vehicles, motorcycles, electric bicycles, drones, ships, trains, and aircraft.

[0023] According to one embodiment, the dielectric breakdown strength of the elastic sheet is characterized by being 7 kV / mm or more. The dielectric breakdown strength refers to the value obtained by varying the thickness of the specimen at the minimum voltage required to cause dielectric breakdown. When the battery is subjected to a situation such as penetration, the elastic sheet stretches and the stretched portion becomes thinner. However, if the dielectric breakdown strength of the elastic sheet satisfies 7 kV / mm or more, the insulating property can be maintained even if the thickness is reduced, thereby preventing a short circuit of the battery and suppressing ignition.

[0024] The dielectric breakdown strength can be measured according to the ASTM D149 standard and can be measured by the same method as Evaluation Example 1 below. The dielectric breakdown strength of the elastic sheet can be, for example, 7 kV / mm to 20 kV / mm, 7 kV / mm to 18 kV / mm, 7 kV / mm to 16 kV / mm, or 7 kV / mm to 15 kV / mm. When the dielectric breakdown strength satisfies the above range, the elastic sheet can maintain its insulating properties even in situations such as penetration, thereby improving the fire safety of the battery.

[0025] The above elastic sheet is characterized by an elongation of 150% or more. The elongation refers to the rate at which a material stretches in a tensile test, and can be, for example, a value measured at a speed of 500 mm / min according to ASTM D3574 and can be measured using the same method as Evaluation Example 2 below. When the elongation is 150% or more, the elastic sheet can maintain its function as an insulating film by appropriately stretching without being easily torn or broken in situations such as penetration, thereby improving the fire safety of the battery. The elongation of the elastic sheet can be, for example, 150% to 250%, or 150% to 200%.

[0026] The tensile strength of the above elastic sheet is characterized by satisfying 3 MPa to 6 MPa. The tensile strength refers to the maximum stress that can withstand a pulling force, and can be measured at a speed of 500 mm / min according to the ASTM D3574 standard, for example, and can be a value measured in the same manner as Evaluation Example 3 below. If the tensile strength is less than 3 MPa, the elastic sheet may tear in situations such as penetration, and may not be able to function as an insulating film, and if the tensile strength exceeds 6 MPa, the elastic sheet may tend to break in situations such as penetration, and may not be able to function as an insulating film. The tensile strength of the elastic sheet according to one embodiment may be, for example, 3.2 MPa to 5.8 MPa.

[0027] An elastic sheet according to an embodiment has an elongation of 150% or more, a tensile strength of 3 MPa to 6 MPa, and an insulation breakdown strength of 7 kV / mm or more, so that when a problem such as a collision or penetration occurs, it can withstand pressure well while being appropriately stretched without being torn or broken, thereby preventing a short circuit of the battery, and thus effectively preventing ignition or explosion of the battery.

[0028] The thickness of the elastic sheet may be approximately 100 μm to 5 mm, for example, 100 μm to 4000 μm, 100 μm to 3000 μm, 100 μm to 2000 μm, 100 μm to 1500 μm, 100 μm to 1000 μm, or 100 μm to 800 μm. In one embodiment, the elastic sheet may be an elastic sheet that has a thin thickness but can implement sufficient resilience to implement a thin battery or to maximize the capacity of the battery, for example, may have a thickness of 100 μm to 800 μm, 200 μm to 800 μm, 300 μm to 800 μm, or 300 μm to 600 μm.

[0029] The elastic sheet may be in the form of a relatively soft, low-modulus pad, or in the form of a relatively hard foam, or in the form of various injection-molded products.

[0030] The above elastic sheet includes a curable resin and an insulating filler.

[0031] curable resin

[0032] Curable resin refers to a polymer that has the property of being cured by energy such as heat or ultraviolet rays. For example, curable resin may include urethane resin, acrylic resin, silicone resin, fluorine resin, styrene resin, vinyl acetate resin, rubber resin, copolymers thereof, or mixtures thereof.

[0033] The above urethane resin may be referred to as polyurethane and refers to a homopolymer or copolymer having a urethane group. The acrylic resin may be, for example, polyacrylate and refers to a homopolymer or copolymer having an acrylic group. The silicone resin refers to a homopolymer or copolymer containing silicon, and the fluorine-based resin refers to a homopolymer or copolymer containing fluorine. These polymers can exhibit appropriate elasticity, strength, and elongation, making them suitable for use as elastic sheets.

[0034] Urethane resins may be derived from polyether polyols. In addition to polyether polyols, polyester polyols may also be used for urethane resins. 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. Furthermore, 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.

[0035] According to one embodiment, a urethane resin may be characterized by being derived from a polyol having a weight average molecular weight of 4,000 g / mol or more. When a high molecular weight polyol having a molecular weight of 4,000 g / mol or more is used, it is advantageous for producing an elastic sheet having an elongation of 150% or more and a tensile strength of 3 MPa to 6 MPa according to one embodiment, thereby improving the fire safety of the elastic sheet. The weight average molecular weight of the polyol may be, for example, 4,000 g / mol to 10,000 g / mol, 5,000 g / mol to 10,000 g / mol, 5,500 g / mol to 8,000 g / mol, or 6,000 g / mol to 7,500 g / mol.

[0036] Acrylic resins may be, for example, derived from C1 to C20 alkyl acrylates, hydroxy C1 to C20 alkyl acrylates, or combinations thereof. Here, C1 to C20 refers 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, acrylate is a concept that includes acrylate and methacrylate.

[0037] The C1 to C20 alkyl acrylate can 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 combinations thereof.

[0038] The hydroxy C1 to C20 alkyl acrylate can 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.

[0039] For example, the acrylic resin may be derived from C1 to C20 alkyl acrylate and hydroxy C1 to C20 alkyl acrylate, and at this time, the mixing ratio of the C1 to C20 alkyl acrylate and the hydroxy C1 to C20 alkyl 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 acrylic resin may exhibit appropriate adhesiveness and is advantageous in realizing excellent compressive strength, stress relaxation rate, and recovery rate.

[0040] Acrylic resins may further include other repeating units derived from acrylic acid, alkoxy-containing acrylates, etc. In addition, the weight average molecular weight of the acrylic resin may be, but is not limited to, 400,000 to 2,000,000.

[0041] Insulating filler

[0042] An elastic sheet according to one embodiment is characterized by including an insulating filler. The insulating filler itself has insulating properties and may be an inorganic insulating filler or an organic insulating filler, and may be an inorganic insulating filler, for example. By adding an insulating filler to the elastic sheet, the elastic sheet has insulating properties and can improve the dielectric breakdown strength and elongation of the elastic sheet, thereby effectively preventing a battery from being short-circuited due to physical force.

[0043] The insulating filler may include, for example, boron nitride (BN), silicon dioxide (SiO2), alumina (AlO3), zinc oxide (ZnO), aluminum hydroxide (Al(OH)3), zirconia (ZrO2), barium oxide (BaO), magnesium oxide (MgO2), aluminum nitride (AlN), strontium oxide (SrO), or combinations thereof.

[0044] The insulating filler may be in the form of particles or fibers. If the insulating filler is in the form of particles, its average particle diameter (D 50 ) may be 10 nm to 25 ㎛, for example, 20 nm to 20 ㎛, 50 nm to 10 ㎛, or 100 nm to 5 ㎛. When the insulating filler has an appropriate particle size, it can be evenly distributed in the elastic sheet and can improve the elongation and dielectric breakdown strength of the elastic sheet. Here, the particle size of the insulating filler is measured through a particle size analyzer, and is the diameter (D) of the particle having a cumulative volume of 50% by volume in the particle size distribution. 50 ) can mean.

[0045] The insulating filler may be included in an amount of 5 to 30 parts by weight based on 100 parts by weight of the curable resin, for example, 5 to 25 parts by weight, or 6 to 20 parts by weight. Alternatively, the insulating filler may be included in an amount of 5 to 30% by weight based on 100% by weight of the elastic sheet, for example, 5 to 20% by weight, 6 to 18% by weight, or 6 to 15% by weight. When the insulating filler is included in the above content range, the elastic sheet can exhibit excellent elongation, tensile strength, and dielectric breakdown strength.

[0046] elastic particles

[0047] In addition to the curable resin and insulating particles, the elastic sheet may optionally further include elastic particles. The elastic particles may be particles made of an elastic polymer such as rubber. The elastic particles can increase the restoring force while maintaining the stress relaxation capacity of the polymer resin.

[0048] The elastic particles may be included in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the polymer resin, for example, 0.5 to 4 parts by weight, or 1 to 3 parts by weight. When the elastic particles are included in this content range, the compressive strength, stress relaxation strength, and resilience can be maximized without lowering the density and adhesiveness of the polymer resin.

[0049] The elastic particles may comprise, for example, a polymer derived from natural rubber, an alkyl acrylate, an olefin, a butadiene, an isoprene, a styrene, an acrylonitrile, a copolymer thereof, or a combination thereof. The elastic particles may have, for example, a glass transition temperature of -70°C to 0°C.

[0050] The alkyl acrylate can be a C1 to C20 alkyl acrylate, 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 combinations thereof.

[0051] The elastic particles may include, for example, polyalkyl acrylate, ethylene-propylene-diene rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, styrene-isoprene rubber, acrylonitrile-butadiene rubber, or combinations thereof.

[0052] The elastic particles may, for example, have a core-shell structure, which is advantageous in exhibiting an appropriate size and elasticity. The core and shell may each comprise, for example, a polyalkyl acrylate. For example, the core may comprise polybutyl (meth)acrylate, and the shell may comprise polymethyl (meth)acrylate. In this case, the dispersibility is excellent, and the compressive strength, stress relaxation capacity, and resilience of the elastic sheet can be improved.

[0053] Elastic particles can be, for example, nano-sized. Specifically, the size of the elastic particles (D 50 ) may be 10 nm to 900 nm, for example, 10 nm to 700 nm, 50 nm to 500 nm, or 100 nm to 400 nm. Elastic particles satisfying these sizes have excellent dispersibility in the elastic sheet and can increase the restoring force while maintaining the stress relaxation ability of the elastic sheet. Here, the size of the elastic particles can be expressed as an average particle diameter or a median particle diameter, and is the diameter (D) of particles having a cumulative volume of 50 vol% in the particle size distribution as measured by a particle size analyzer. 50 ) can mean.

[0054] inorganic particles

[0055] The elastic sheet may further contain inorganic particles, in which case the modulus and compressive strength of the elastic sheet can be improved while simultaneously improving the recovery rate.

[0056] Inorganic particles may include, for example, alumina, titania, boehmite, barium sulfate, calcium carbonate, calcium phosphate, amorphous silica, mesoporous silica, fumed silica, crystalline glass particles, kaolin, talc, silica-alumina composite oxide particles, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, mica, magnesium oxide, or combinations thereof.

[0057] The inorganic particles may be included, for example, in an amount of 0.001 to 50 parts by weight, for example, 0.01 to 45 parts by weight, or 0.1 to 40 parts by weight, based on 100 parts by weight of the polymer resin. In this case, the compressive strength, stress relaxation rate, and recovery rate of the elastic sheet can be improved without deteriorating the properties of the polymer resin.

[0058] The average particle size of the inorganic particles may be 0.1 ㎛ to 5 ㎛, for example, 0.1 ㎛ to 2.5 ㎛, or 0.2 ㎛ to 2 ㎛. The average particle size is measured using a laser scattering particle size distribution meter, and is the median particle size (D) when 50% is accumulated from the small particle side in volume conversion. 50 ) may mean.

[0059] hollow particles

[0060] The elastic sheet may further include hollow particles. Hollow particles are particles with an internal void, and may be expressed as hollow spheres or hollow beads, and may be hollow nanoparticles or hollow microparticles. When the elastic sheet includes hollow particles, the sheet can increase compressive strength while maintaining an appropriate density and can exhibit a foam shape.

[0061] The hollow particles may be included in an amount of 1 to 8 parts by weight based on 100 parts by weight of the polymer resin, for example, 1 to 7 parts by weight, or 2 to 6 parts by weight. When the hollow particles are included in this content range, it is advantageous for producing an elastic sheet in a foam form, and the compressive strength, stress relaxation ability, and resilience of the elastic sheet can be improved.

[0062] The hollow particles may be inorganic hollow particles, organic hollow particles, or a combination thereof. That is, the hollow particles may be composed of an inorganic material or an organic material such as a polymer.

[0063] The inorganic hollow particles may include, for example, glass, metal oxides, metal carbides, metal fluorides, or combinations thereof. Specifically, the inorganic hollow particles may be formed of glass, silicon oxide, nickel oxide, barium oxide, platinum oxide, zinc oxide, aluminum oxide, zirconium oxide, iron oxide, titanium oxide, calcium carbonate, magnesium fluoride, or combinations thereof, and as an example, the inorganic hollow particles may be glass bubbles.

[0064] The organic hollow particles may include, for example, an acrylic resin, a vinyl chloride resin, a urea resin, a phenolic resin, a rubber, or a combination thereof. Furthermore, the organic hollow particles may be expandable or non-expandable, and the expandable organic hollow particles may be, for example, expandable at 120°C to 150°C.

[0065] Size of hollow particles (D 50 ) may be, for example, a micro size, and specifically, may be 1 ㎛ to 100 ㎛, 5 ㎛ to 80 ㎛, 10 ㎛ to 60 ㎛, or 20 ㎛ to 50 ㎛. Hollow particles having such a size are advantageous for making an elastic sheet in a foam form, and can lower the density and improve stress relaxation and resilience while improving the compressive strength of the elastic sheet. Here, the size of the hollow particles can be expressed as an average particle diameter or a median particle diameter, and is the diameter (D) of particles having a cumulative volume of 50% by volume in a particle size distribution, as measured by a particle size analyzer. 50 ) can mean.

[0066] Other additives

[0067] In addition to the components described above, the elastic sheet may further include appropriate additives, such as an initiator, a crosslinking agent, a coupling agent, a stabilizer, etc. Each additive may be included in an appropriate amount according to the purpose, for example, it may be included in an amount of 0.001 to 1 part by weight, for example, 0.01 to 0.8 parts by weight, based on 100 parts by weight of the polymer resin.

[0068] Additionally, the elastic sheet may further comprise 0.1 to 10 parts by weight of a pigment, 0.1 to 10 parts by weight of an antioxidant, 0.1 to 10 parts by weight of a lubricant, 0.1 to 10 parts by weight of an antistatic agent, or a combination thereof, per 100 parts by weight of the polymer resin.

[0069] All-solid-state secondary battery

[0070] In one embodiment, an all-solid-state secondary battery is provided, comprising two or more cell structures including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and elastic sheets positioned between the cell structures and / or at the outermost surface of the cell structures. At least one of the elastic sheets in the battery may be the elastic sheet described above.

[0071] Fig. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to Fig. 1, an all-solid-state secondary battery (100) is a structure in which a cell structure in which a negative electrode (400) including a negative electrode current 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 current collector (201) are laminated is housed in a battery case. Although Fig. 1 illustrates an assembly in which two cell structures including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200) are laminated, three or more cell structures may be laminated, for example, 2 to 200, 3 to 100, 4 to 50, etc. may be laminated.

[0072] The all-solid-state secondary battery (100) may include an elastic sheet (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). That is, the elastic sheet (500) may be positioned between the cell structures and / or at the outermost surface of the cell structures. According to one embodiment, at least one of the elastic sheets (500) in the battery may be the aforementioned elastic sheet. In this case, the all-solid-state secondary battery may not only resolve the problem of stress concentration due to volume change by the elastic sheet, but also effectively suppress short-circuiting when problems such as penetration occur, thereby improving thermal and electrical safety.

[0073] anode

[0074] In one embodiment, the device comprises a current collector and a positive electrode active material layer positioned on the current collector, wherein the positive electrode active material layer comprises a positive electrode active material and optionally may comprise a solid electrolyte, a binder, and / or a conductive material.

[0075] positive electrode active material

[0076] 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.

[0077] 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, lithium-rich layered oxide, or a combination thereof.

[0078] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more based on 100 mol% of metals excluding lithium in a lithium transition metal composite oxide. The nickel content in the high-nickel cathode active material may be 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. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0079] As a more specific 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 Ni 1-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 eO2(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)

[0080] 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; Q is Ti, Mo, Mn, or a combination thereof; Z is Cr, V, Fe, Sc, Y, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0081] 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.

[0082] [Chemical Formula 11]

[0083] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0084] 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.

[0085] 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.

[0086] [Chemical Formula 12]

[0087] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0088] 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 3is 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.

[0089] [Chemical Formula 13]

[0090] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0091] 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.

[0092] [Chemical Formula 14]

[0093] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0094] 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.

[0095] The average particle diameter (D) of the above positive electrode active material 50 ) may be 1 ㎛ to 25 ㎛, for example, 3 ㎛ to 25 ㎛, 1 ㎛ to 20 ㎛, 1 ㎛ to 18 ㎛, 3 ㎛ to 15 ㎛, or 5 ㎛ to 15 ㎛. For example, the positive electrode active material may have an average particle diameter (D 50 ) with small particles of 1 ㎛ to 9 ㎛ and an average particle diameter (D 50 ) may include particles having a particle size range of 10 ㎛ to 25 ㎛. The positive electrode active material having such a particle size range can be harmoniously mixed with other components in the positive electrode active material layer and can realize high capacity and high energy density. Here, the average particle size is obtained by selecting 20 or so random particles from a scanning electron microscope image of the positive electrode active material, measuring their particle sizes (diameter, or major axis, or major axis length), and then obtaining a particle size distribution, and in the particle size distribution, the diameter (D) of the particles having a cumulative volume of 50% by volume 50 ) may be taken as the average particle diameter.

[0096] 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.

[0097] 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.

[0098] The positive electrode active material may be included in an amount of 55 wt% to 99.5 wt% based on 100 wt% of the positive electrode active material layer, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0099] bookbinder

[0100] The binder helps the positive electrode active material particles adhere well to each other and also helps the positive electrode active material adhere well to the current collector. Representative examples of binders 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.

[0101] Challenge

[0102] Conductive materials are used to impart conductivity to electrodes, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0103] The content of the binder and the conductive agent may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0104] The cathode 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 specific descriptions thereof will be provided later in the section on the solid electrolyte layer.

[0105] For 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%.

[0106] 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.

[0107] Al may be used as the above current collector, but is not limited thereto.

[0108] cathode

[0109] An anode for an all-solid-state secondary battery may include 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 and / or a conductive material.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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. The Si-based negative electrode active material is silicon, a silicon-carbon composite, SiOx(0 <x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소(Si를 제외함), 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합에서 선택됨), 또는 이들의 조합일 수 있다. 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn계 합금 또는 이들의 조합일 수 있다.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% based on the total weight of the negative active material layer. For example, the negative active material layer may include 90 wt% to 99 wt% of the negative active material, 0.5 wt% to 5 wt% of the binder, and 0 wt% to 5 wt% of the conductive material.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] precipitation cathode

[0126] As another example, the negative electrode for an all-solid-state secondary battery may be a precipitation-type negative electrode. The precipitation-type negative electrode may refer to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which lithium metal or the like is precipitated or deposited on the negative electrode when the battery is charged, and this acts as a negative electrode active material.

[0127] Fig. 2 is a schematic cross-sectional view of an all-solid-state secondary 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 secondary 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 during charging, high-density lithium metal is precipitated or deposited between the current collector (401) and the negative electrode coating layer (405) or on 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 secondary battery that has been charged more than once, the precipitation-type negative electrode (400) may include, for example, 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 lithium metal layer (404) refers to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may be referred to as a metal layer, a lithium layer, a lithium deposition layer, or a negative electrode active material layer.

[0128] The above cathode coating layer (405) may be referred to as a lithium electrodeposition induction layer or a cathode catalyst layer, and may include a metal, a carbon material, or a combination thereof.

[0129] The metal may be a lithium-philic metal, and may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one of these or may be composed of several types of alloys. When the metal is present in the form of particles, the average particle diameter (D 50 ) may be less than about 4 μm, for example, 10 nm to 4 μm.

[0130] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0131] 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 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state secondary 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.

[0132] The above-described cathode coating layer (405) may include, for example, the above-described lithium-philic metal and amorphous carbon, in which case the precipitation of the lithium metal may be effectively promoted. As a specific example, the cathode coating layer (405) may include a composite in which a lithium-philic metal is supported on amorphous carbon.

[0133] 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.

[0134] The thickness of the cathode coating layer (405) may be, for example, 100 nm to 20 ㎛, or 500 nm to 10 ㎛, or 1 ㎛ to 5 ㎛.

[0135] 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 secondary 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 500 nm.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] solid electrolyte layer

[0140] The solid electrolyte layer comprises a solid electrolyte. The 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. According to one embodiment, the solid electrolyte layer may comprise a sulfide-based solid electrolyte.

[0141] Sulfide-based solid electrolyte

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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 can further form a close interface between an electrode layer and a solid electrolyte layer. An all-solid-state secondary battery including the same can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0147] The argyrodite-type sulfide-based solid electrolyte particles may include, for example, a compound represented by the chemical formula 21 below.

[0148] [Chemical Formula 21]

[0149] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0150] 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 , 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.

[0151] 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.

[0152] For example, in chemical formula 21, a+b+c+h=7, d+e=1, and f+g+h=6.

[0153] 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.

[0154] An argyrodite-type sulfide-based solid electrolyte can be prepared, for example, by mixing lithium sulfide and phosphorus sulfide, optionally a lithium halide. After mixing these, a heat treatment may be performed. The heat treatment may be performed at a temperature in the range of 400°C to 600°C, for example, 450°C to 500°C, or 460°C to 490°C, and for 5 to 30 hours, 10 to 24 hours, or 15 to 20 hours. When heat treating under the above conditions, ionic conductivity can be maximized. 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 first heat treatment resultant again and calcining at 350°C to 800°C.

[0155] Average particle diameter (D) of sulfide-based solid electrolyte particles 50) may be, for example, 0.1 ㎛ to 5.0 ㎛ or 0.1 ㎛ to 3.0 ㎛, may be small particles of 0.1 ㎛ to 1.9 ㎛, or may be 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 diameter of 0.1 ㎛ to 1.9 ㎛ and large particles having an average particle diameter of 2.0 ㎛ to 5.0 ㎛. The average particle diameter of the sulfide-based solid electrolyte particles may be measured by an electron microscope image, and for example, a particle size distribution is obtained by measuring the size (diameter or major axis length) of about 20 particles in a scanning electron microscope image, where D 50 It may have been calculated.

[0156] Oxide-based solid electrolyte

[0157] 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 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 mixtures thereof.

[0158] Halide-based solid electrolyte

[0159] 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.

[0160] 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.

[0161] bookbinder

[0162] 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, and the like. copolymers, or combinations thereof.

[0163] 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.

[0164] Other ingredients

[0165] The solid electrolyte layer may optionally further comprise an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0166] 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.

[0167] 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.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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 negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a laminated battery in which the structure of the unit cell is repeated.

[0174] 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-sized 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 that require large amounts of power storage, and for example, it can be used in motorcycles, electric bicycles, drones, ships, trains, aircraft, or power tools. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0175] Hereinafter, examples and comparative examples of the present invention are described. The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0176] Example 1

[0177] 1. Manufacturing of elastic sheets

[0178] 78.36 parts by weight of polyol (VORANOL™ CP6001) having a weight average molecular weight of 6000 g / mol, 7.64 parts by weight of isocyanate (BASF, Lupranate M11s), 0.025 parts by weight of 1,4-butanediol as a crosslinking agent, 0.125 parts by weight of dibutyltin dilaurate as a metal catalyst, 3.5 parts by weight of glass bubbles (S60), 0.35 parts by weight of thermally expandable microspheres (FN-100MD), and 10 parts by weight of boron nitride as an insulating filler were mixed in a stirrer for 1 hour. This was coated on a PET film and heated to 150°C to produce a urethane-based elastic sheet having a thickness of approximately 300 μm.

[0179] 2. Manufacturing of all-solid-state secondary batteries

[0180] LiNi coated with Li2O-ZrO2 0.8 Co 0.15 Mn0.05 A cathode composition was prepared by mixing 85 wt% of an O2 cathode active material, 13.5 wt% of a lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of a polyvinylidene fluoride binder, and 0.5 wt% of a carbon nanotube conductive material. The prepared cathode composition was coated on an aluminum cathode current collector, dried, and rolled to prepare a cathode.

[0181] Primary entry (D 50 ) carbon black with an average particle diameter (D) of about 30 nm 50 ) was prepared by mixing silver (Ag) having a diameter of approximately 60 nm in a weight ratio of 3:1, and 0.25 g of the above complex was added to 2 g of an NMP solution containing 7 wt% of polyvinylidene fluoride binder and mixed to prepare a negative electrode coating layer composition. This was applied to a nickel foil current collector using a bar coater and vacuum-dried to prepare a deposition-type negative electrode in which a negative electrode coating layer was formed on the current collector.

[0182] An argyrodite-type solid electrolyte Li6PS5Cl(D) was added to a binder solution in which an acrylic binder (SX-A334, Zeon) was dissolved in an isobutyryl isobutyrate (IBIB) solvent. 50 =3㎛) was added and stirred to prepare a slurry. The slurry contains 98.5 wt% of solid electrolyte and 1.5 wt% of binder. The slurry was applied onto a release PET film using a bar coater and dried at room temperature to prepare a solid electrolyte layer.

[0183] Bi-cell type cell structures were manufactured by stacking cathode / solid electrolyte / anode / solid electrolyte / cathode in that order. An elastic sheet manufactured between two cell structures and on the outermost surface of the cell structures was interposed. The laminated structure was placed in an aluminum pouch laminate film and subjected to warm isostatic pressing (WIP) at 80°C and 500 MPa for 30 minutes to manufacture an all-solid-state secondary battery.

[0184] Example 2

[0185] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 1, except that instead of using glass bubbles and thermally expandable microspheres, nitrogen was injected at a rate of 200 cc / min and stirred for 5 minutes to manufacture an elastic sheet.

[0186] Comparative Example 1

[0187] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 1, except that a polyol having a weight average molecular weight of 3400 g / mol (SANNIX FA-103) was used instead of the 6000 g / mol polyol.

[0188] Comparative Example 2

[0189] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 2, except that a polyol having a weight average molecular weight of 3400 g / mol (SANNIX FA-103) was used instead of the 6000 g / mol polyol.

[0190] Comparative Example 3

[0191] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 1, except that the content of each component was changed as shown in Table 1 below and no insulating filler was used.

[0192] Comparative Example 4

[0193] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 2, except that the content of each component was changed as shown in Table 1 below and no insulating filler was used.

[0194] The components and contents of the elastic sheets of each example and comparative example are shown in Table 1 below.

[0195] (Wt%)Example 1Example 2Comparative Example 1Comparative Example 2Comparative Example 3Comparative Example 4Polyol(M W:6000)78.3681.83--87.3690.87Polyol(MW:3400)--78.3581.83--Isocyanate7.648.027.648.028.648.981,4-butandiol0.0250.0250.0250.0250.0250.0250.025Dibutyltin dilaurate0.1250.1250.1250.1250.1250.125Glass bubble3.5-3.5-3.5-Thermal expansion microsphere0.35-0.35-0.35-Nitrogen (200cc / min)-О-О-ОInsulating filler10101010--

[0196] Example 3

[0197] 1. Manufacturing of elastic sheets

[0198] 42.93 parts by weight of 2-ethylhexyl acrylate, 21.46 parts by weight of isobornyl acrylate, and 21.46 parts by weight of 4-hydrobutyl acrylate were mixed, and 0.025 parts by weight of 1,6-hexanediol diacrylate as a crosslinking agent, 0.125 parts by weight of an initiator (Igacure 651), 0.5 parts by weight of polymer microspheres (820DET40), and 3.5 parts by weight of glass bubbles (K-1), and 10 parts by weight of boron nitride as an insulating filler were mixed in a stirrer for 1 hour. This was applied on a PET film and irradiated at 10 mW / cm 2 An acrylic elastic sheet with a thickness of about 300 ㎛ was manufactured by irradiating it with ultraviolet rays for about 3 minutes using a century-old UV lamp.

[0199] Other than that, an all-solid-state secondary battery was manufactured in substantially the same manner as Example 1.

[0200] Examples 4 to 7 and Comparative Examples 5 to 9

[0201] An elastic sheet and an all-solid-state secondary battery were manufactured in substantially the same manner as in Example 3, except that the components and contents of the elastic sheet were modified as shown in Table 2 below.

[0202] (% by weight) Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 2-Ethylhexyl acrylate 4 2.93 2 2.46 4 0.43 2 0.7 1 2 6.96 4 7.93 8.7 9 37.93 2 2.96 1 8.17 Isobonyl acrylate 2 1.46 4 4.93 2 0.2 1 4 1 4 3 5.94 2 3.96 6 5.8 9 18.96 4 5.93 1 8.17 4-hydroxybutyl acrylate21.4622.4620.2120.7126.9623.9613.1818.9622.9654.51Crosslinking agent0.0250.0250.0250.0250.0250.0250.0250.0250.0250.0250.0250.025Initiator0.125 ... Filler 10615136-82045

[0203] Evaluation Example 1: Insulation Breakdown Strength

[0204] The elastic sheets manufactured in the examples and comparative examples were placed between heavy cylindrical electrodes that carried current, with a specimen thickness of 300 μm as a standard according to ASTM D149. After applying the initial voltage, the voltage was increased at a constant rate of 0.5 kV / sec, and the voltage at the breakdown point was measured. The breakdown strength was then divided by the specimen thickness to determine the dielectric breakdown strength. The results are shown in Tables 3 and 4.

[0205] Evaluation Example 2: Elongation

[0206] The elongation of the elastic sheets manufactured in the examples and comparative examples was measured at a speed of 500 mm / min according to ASTM D3574, and the results are shown in Tables 3 and 4. Elongation refers to the extent to which a specimen stretches in a tensile test.

[0207] Evaluation Example 3: Tensile strength

[0208] The tensile strength of the elastic sheets manufactured in the examples and comparative examples was measured at a speed of 500 mm / min according to the ASTM D3574 standard, and the results are shown in Tables 3 and 4.

[0209] Evaluation Example 4: Penetration Test

[0210] A penetration test was performed on elastic sheets having a thickness of 300 ㎛ manufactured in the examples and comparative examples at a penetration speed of 0.1 mm / s and a pin thickness of 1 mmΦ to be penetrated, and the results are shown in Tables 3 and 4.

[0211] ClassificationExample 1Example 2Example 3Example 4Example 5Example 6Example 7Insulation Breakdown Strength (kV / mm)11.812.110.27.315.714.47.5Elongation (%)(500mm / min)165.4170.3194.4178.2166.7152.1198.8Tensile Strength (MPa)4.64.34.33.84.75.83.2Penetration Test (Thickness: 300um)PassPassPassPassPassPassPass

[0212] ClassificationComparative Example 1Comparative Example 2Comparative Example 3Comparative Example 4Comparative Example 5Comparative Example 6Comparative Example 7Comparative Example 8Comparative Example 9Insulation Breakdown Strength (kV / mm)10.411.24.75.14.48.116.76.45.8Elongation (%)(500mm / min)129.6132.4205.7223.9250.7150.4150.7178.2138.1Tensile Strength (MPa)2.42.22.72.52.37.86.23.82.7Penetration Test (Thickness: 300um)IgnitionIgnitionIgnitionIgnitionIgnitionIgnitionIgnitionIgnition

[0213] Referring to Tables 3 and 4, it can be confirmed that the examples satisfy an insulation breakdown strength of 7 kV / mm or more, a tensile strength of 3 to 6 MPa, an elongation of 150% or more, and pass the penetration test without ignition upon penetration. In addition, it was confirmed that the insulation was maintained up to about 90 ㎛, which is 30% of the initial thickness of 300 ㎛, when the elastic sheet was stretched during the penetration test.

[0214] In Comparative Examples 1 and 2, which applied low molecular weight polyol among urethane-based elastic sheets, the tensile strength was less than 3 MPa and the elongation was less than 150%. In these cases, it was confirmed that the elastic sheet was torn upon penetration and could not function as an insulating film. In Comparative Examples 3 and 4, which did not apply insulating filler among urethane-based elastic sheets, the tensile strength was less than 3 MPa and the dielectric breakdown strength was low at less than 7 kV / mm. Accordingly, it was confirmed that the insulation was not maintained upon penetration and ignition occurred.

[0215] Among the acrylic elastic sheets, Comparative Example 5 had a tensile strength of less than 3 MPa and an insulation breakdown strength of less than 7 kV / mm, and therefore, when penetrated, the insulation was not maintained, resulting in ignition. Comparative Examples 6 and 7 had a tensile strength exceeding 6 MPa and an elongation of 150% or more, but in these cases, the elastic sheet was broken when penetrated, confirming that it could not function as an insulating film. Comparative Example 8 had a insulation breakdown strength of less than 7 kV / mm, and thus, when penetrated, the insulation was not sufficiently maintained, resulting in ignition. Comparative Example 9 had a tensile strength of less than 3 MPa, an elongation of less than 150%, and an insulation breakdown strength of less than 7 kV / mm, and the elastic sheet was torn when penetrated, failing to function as an insulating film.

[0216] Finally, it was confirmed that the tensile strength of the elastic sheet should be in the range of 3 MPa to 6 MPa, the elongation should be 150% or more, and the insulation breakdown strength should be 7 kV / mm or more to prevent ignition by penetration.

[0217] Evaluation Example 5: Battery Penetration Evaluation

[0218] A penetration test was performed on the all-solid-state secondary battery manufactured in Example 1 at a maximum voltage charge state with a penetration speed of 0.1 mm / s, a pin thickness of 1 mmΦ, and a depth of 2 mm, and the results are shown in Fig. 3.

[0219] In Fig. 3, the part indicated by the left dotted square is the first penetration, where a short circuit occurs, but the voltage is recovered and the temperature does not rise. The dotted square in the middle is the second penetration, where a short circuit similarly occurs, but the voltage is recovered and the temperature does not rise significantly and then goes down again. At this time, the maximum temperature is confirmed to be 39.2°C. Accordingly, it can be seen that the all-solid-state secondary battery of Example 1 effectively demonstrated the insulating performance of the elastic sheet in the penetration test, and no overheating or ignition occurred.

[0220] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

[0221] [Explanation of symbols]

[0222] 100: All-solid-state secondary battery 200: Cathode

[0223] 201: Cathode current collector 203: Cathode active material layer

[0224] 300: Solid electrolyte layer 400: Cathode

[0225] 401: Negative current collector 403: Negative active material layer

[0226] 404: Lithium metal layer 405: Cathode coating layer

[0227] 500: Elastic sheet

Claims

1. An elastic sheet for an all-solid-state secondary battery comprising a curable resin and an insulating filler, An elastic sheet for an all-solid-state secondary battery, wherein the elastic sheet has an insulation breakdown strength of 7 kV / mm or more, an elongation of 150% or more, and a tensile strength of 3 MPa to 6 MPa.

2. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the insulation breakdown strength of the elastic sheet is 7 kV / mm to 16 kV / mm.

3. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the elastic sheet has an elongation of 150% to 200%.

4. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the thickness of the elastic sheet is 100 ㎛ to 5 mm.

5. In paragraph 4, An elastic sheet for an all-solid-state secondary battery, wherein the thickness of the elastic sheet is 100 ㎛ to 800 ㎛.

6. In paragraph 1, The above elastic sheet is an elastic sheet for an all-solid-state secondary battery in the form of a foam rubber, a sheet, a foam sheet, an injection molded product, or a foam injection molded product.

7. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the curable resin comprises a urethane resin, an acrylic resin, a silicone resin, a fluorine-based resin, a styrene-based resin, a vinyl acetate-based resin, a rubber resin, a copolymer thereof, or a mixture thereof.

8. In paragraph 1, The above curable resin includes a urethane resin, An elastic sheet for an all-solid-state secondary battery, wherein the above urethane resin is derived from a polyol having a weight average molecular weight of 4,000 g / mol or more.

9. In paragraph 8, An elastic sheet for an all-solid-state secondary battery, wherein the above urethane resin is derived from a polyol having a weight average molecular weight of 5,000 g / mol to 10,000 g / mol.

10. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the insulating filler comprises boron nitride (BN), silicon dioxide (SiO2), alumina (AlO3), zinc oxide (ZnO), aluminum hydroxide (Al(OH)3), zirconia (ZrO2), barium oxide (BaO), magnesium oxide (MgO2), aluminum nitride (AlN), strontium oxide (SrO), or a combination thereof.

11. In paragraph 1, The above insulating filler is in particle form and has an average particle diameter (D 50 ) is an elastic sheet for an all-solid-state secondary battery having a thickness of 10 nm to 25 μm.

12. In paragraph 1, An elastic sheet for an all-solid-state secondary battery, wherein the insulating filler is contained in an amount of 5 to 30 parts by weight based on 100 parts by weight of the curable resin.

13. In paragraph 1, The above-mentioned elastic sheet for an all-solid-state secondary battery further contains elastic particles, An elastic sheet for an all-solid-state secondary battery, wherein the elastic particles are derived from alkyl acrylate, olefin, butadiene, isoprene, styrene, acrylonitrile, copolymers thereof, or a combination thereof.

14. In paragraph 13, The average particle diameter (D) of the above elastic particles 50 ) is an elastic sheet for an all-solid-state secondary battery having a thickness of 10 nm to 900 nm.

15. In paragraph 14, An elastic sheet for an all-solid-state secondary battery, wherein the elastic particles are contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the curable resin.

16. In paragraph 1, The above elastic sheet for an all-solid-state secondary battery further contains inorganic particles, An elastic sheet for an all-solid-state secondary battery, wherein the inorganic particles include titania, boehmite, barium sulfate, calcium carbonate, calcium phosphate, amorphous silica, mesoporous silica, fumed silica, crystalline glass particles, kaolin, talc, silica-alumina composite oxide particles, calcium fluoride, lithium fluoride, zeolite, molybdenum sulfide, mica, or a combination thereof.

17. In Article 16, An elastic sheet for an all-solid-state secondary battery, wherein the inorganic particles are contained in an amount of 0.001 to 50 parts by weight based on 100 parts by weight of the curable resin.

18. In paragraph 1, The above elastic sheet for an all-solid-state secondary battery further contains an additive, An elastic sheet for an all-solid-state secondary battery, wherein the additive comprises an initiator, a crosslinking agent, a coupling agent, a stabilizer, or a combination thereof.

19. In Article 18, An elastic sheet for an all-solid-state secondary battery, wherein the additive is contained in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the curable resin.

20. Comprising two or more cell structures including an anode, a cathode, and a solid electrolyte layer positioned between the anode and the cathode, An all-solid-state secondary battery comprising an elastic sheet according to any one of claims 1 to 19 positioned between the cell structures and / or at the outermost surface of the cell structures.

21. In Article 20, The above all-solid-state secondary battery is an all-solid-state secondary battery applicable to electric vehicles, motorcycles, electric bicycles, drones, ships, trains, or aircraft.

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