Elastic sheet for all-solid rechargeable battery and all-solid rechargeable battery

Abstract

The present application relates to an elastic sheet for an all-solid rechargeable battery and an all-solid rechargeable battery comprising same. The elastic sheet for an all-solid rechargeable battery has a thickness of 100-500 micrometers and a strain of 10% or less in a vacuum environment of 0.1 MPa. The all-solid rechargeable battery comprises: a plurality of unit cells stacked in one direction and each including a solid electrolyte layer; and elastic sheets for all-solid rechargeable batteries, positioned between the plurality of unit cells.

Description

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

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

[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 are an elastic sheet for an all-solid-state battery and an all-solid-state secondary battery, which alleviate stress transmitted to an all-solid-state unit cell and stress generated in the all-solid-state unit cell during repeated charge and discharge, thereby suppressing damage to the all-solid-state unit cell and improving charge and discharge efficiency and life characteristics of the all-solid-state secondary battery.

[0005] In addition, as the laminated all-solid-state unit cells are exposed to a vacuum environment during battery manufacturing, an elastic sheet for an all-solid-state battery and an all-solid-state secondary battery are provided that suppress the misalignment of the all-solid-state unit cells laminated in one direction even when the elastic sheet is deformed.

[0006] One aspect provides an elastic sheet for an all-solid-state secondary battery having a thickness of 100 ㎛ to 500 ㎛ and a strain of 10% or less in a vacuum environment of 0.1 MPa.

[0007] The thickness of the above-mentioned elastic sheet for the all-solid-state secondary battery may be 300 μm.

[0008] The above strain may include the strain of the width of the elastic sheet for the all-solid-state secondary battery.

[0009] The above elastic sheet for the all-solid-state secondary battery may include foam.

[0010] The above-mentioned elastic sheet for a solid-state secondary battery includes a polymer resin, and the polymer resin may include polyacrylate, polyurethane, silicone, fluorine-based polymer, polyether polyol, polyester polyol, polycarbonate polyol, copolymers thereof, or combinations thereof.

[0011] The polyacrylate may include a C1 to C20 alkyl acrylate, a hydroxy C1 to C20 alkyl acrylate, or a combination thereof.

[0012] The above elastic sheet for an all-solid-state secondary battery may further include hollow particles.

[0013] The above 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.

[0014] The hollow particles may be inorganic hollow particles, organic hollow particles, or a combination thereof, and the inorganic hollow particles may include glass, metal oxide, metal carbide, metal fluoride, or a combination thereof, and the organic hollow particles may include acrylic resin, vinyl chloride resin, urea resin, phenol resin, or a combination thereof.

[0015] The average particle diameter (D50) of the above hollow particles may be 2 µm to 100 µm.

[0016] The above-mentioned elastic sheet for an all-solid-state secondary battery further includes elastic particles, and the elastic particles may include alkyl acrylate, olefin, butadiene, isoprene, styrene, acrylonitrile, a copolymer thereof, or a combination thereof.

[0017] 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.

[0018] The average particle diameter (D50) of the above elastic particles may be 10 nm to 900 nm.

[0019] The above-mentioned elastic sheet for an all-solid-state secondary battery further comprises inorganic particles, and the inorganic particles may include 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 a combination thereof.

[0020] The above inorganic particles may be included in an amount of 0.001 to 50 parts by weight based on 100 parts by weight of the polymer resin.

[0021] The above-mentioned elastic sheet for a solid-state secondary battery further includes an additive, and the additive may include an initiator, a crosslinking agent, a coupling agent, a stabilizer, an inert gas, or a combination thereof.

[0022] In addition, one side provides an elastic sheet for an all-solid-state secondary battery having a thickness of 100 μm and a strain of 30% or less in a vacuum environment of 0.1 MPa.

[0023] In addition, one side provides an elastic sheet for an all-solid-state secondary battery having a thickness of 500 μm and a strain of 5% or less in a vacuum environment of 0.1 MPa.

[0024] In addition, one side provides an all-solid-state secondary battery including a plurality of unit cells including solid electrolyte layers laminated in one direction, and an elastic sheet for the all-solid-state secondary battery positioned between the plurality of unit cells.

[0025] The device may further include a case that houses the plurality of unit cells and the elastic sheet for the all-solid-state secondary battery inside a vacuum environment of 0.1 MPa.

[0026] According to one embodiment, an elastic sheet for an all-solid-state battery and an all-solid-state secondary battery are provided, which alleviate stress transmitted to an all-solid-state unit cell and stress generated in the all-solid-state unit cell during repeated charge and discharge cycles, thereby suppressing breakage of the all-solid-state unit cell and improving charge and discharge efficiency and life characteristics of the all-solid-state secondary battery.

[0027] In addition, since the elastic sheet placed between the all-solid unit cells stacked in one direction is deformed below a certain level even when exposed to a vacuum environment during battery manufacturing, misalignment of the all-solid unit cells can be suppressed.

[0028] Figure 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment.

[0029] Figure 2 is a cross-sectional view showing an all-solid-state secondary battery according to another embodiment.

[0030] Figure 3 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Examples 1, 2, 3, and Comparative Example 1.

[0031] Figure 4 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Example 4 and Comparative Example 2.

[0032] Figure 5 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Example 5 and Comparative Example 3.

[0033] Hereinafter, specific examples will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0034] 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.

[0035] Here, “combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0036] It should be understood that the terms "include," "comprising," or "having" herein 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.

[0037] To clearly represent multiple layers and regions in the drawings, the 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 is another element in between. Conversely, when an element is said to be "directly over" another element, it means that there is no other element in between.

[0038] Also, here, “layer” includes not only the shape formed on the entire surface when observed in a plan view, but also the shape formed on a portion of the surface.

[0039] 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 a transmission electron microscope image or a scanning electron microscope image. 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 can mean the diameter (D50) of particles in a particle size distribution that have a cumulative volume of 50% by volume. In addition, unless otherwise defined, the average particle size can be obtained by randomly measuring the sizes (diameters or major axis lengths) of about 20 particles in a scanning electron microscope image to obtain a particle size distribution, and taking the diameter (D50) of particles in the particle size distribution that have a cumulative volume of 50% by volume as the average particle size.

[0040] Here, “or” is not interpreted in an exclusive sense, for example, “A or B” is interpreted to include A, B, A+B, etc.

[0041] “Metal” is interpreted as a concept that includes common metals, transition metals, and metalloids (semi-metals).

[0042] All-solid-state secondary battery

[0043] Figure 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment.

[0044] Referring to FIG. 1, an all-solid-state secondary battery (1000) according to one embodiment includes a structure in which a plurality of unit cells (100) including a negative electrode (110) as an anode including a negative electrode current collector (111) and a negative electrode active material layer (112), a solid electrolyte layer (120), and a positive electrode (130) as a cathode including a positive electrode active material layer (132) and a positive electrode current collector (131) are stacked in one direction (for example, a vertical direction) to form a vacuum environment (VE), and are housed in a case (300). The all-solid-state secondary battery (1000) further includes an elastic sheet (200) on the outer side of at least one of the positive electrode (130) and the negative electrode (110). The elastic sheet (200) may be positioned on the outer side of the plurality of unit cells (100) and between the plurality of unit cells (100), but is not limited thereto. In FIG. 1, a laminate is illustrated in which two unit cells (100) including a cathode (110), a solid electrolyte layer (120), and an anode (130) are laminated, but the present invention is not limited thereto, and the laminate may include three or more unit cells (100). For example, the laminate may include 2 to 100 unit cells (100), 3 to 50 unit cells (100), or 4 to 20 unit cells (100).

[0045] An all-solid-state secondary battery (1000) is manufactured by pressurizing a plurality of unit cells (100) during the manufacturing process, and may include a structure in which charging and discharging are performed in a pressurized state. Here, the elastic sheet (200) may be expressed as a buffer layer or an elastic layer, and may serve to ensure that pressure is uniformly transmitted to the plurality of unit cells (100) to ensure good contact between solid components included in the plurality of unit cells (100), and may also serve to alleviate stress transmitted to a solid electrolyte layer, etc., and may serve to suppress cracks from occurring in the solid electrolyte layer due to stress accumulation according to changes in the thickness of the electrode during charging and discharging.

[0046] As shown in Fig. 1, the elastic sheet (200) can be positioned between a plurality of unit cells (100) and can also be positioned on the outermost surface of the plurality of unit cells (100). Considering that the thickness of the negative electrode changes significantly during charge and discharge due to lithium deposition or dendrite formation, the elastic sheet (200) can be positioned on the outer side of the negative electrode (110), for example, on the opposite side of the surface of the negative electrode (110) where the solid electrolyte layer (120) is in contact, thereby buffering problems due to thickness changes. In addition, the elastic sheet (200) can be positioned on the outer side of the positive electrode (130) and / or the negative electrode (110), thereby preventing the phenomenon of deterioration by reaction with lithium, and thus increasing the Coulombic efficiency of the all-solid-state secondary battery.

[0047] A plurality of unit cells (100) stacked in one direction included in an all-solid-state secondary battery can be positioned within an alignment tolerance (AT) even if an elastic sheet (200) is deformed according to vacuum pressure. For example, the alignment tolerance (AT) of the plurality of unit cells (100) can include a maximum range of alignment misalignment values ​​that can be allowed in the battery in a horizontal direction intersecting the vertical direction in which the plurality of unit cells (100) are stacked.

[0048] elastic sheet

[0049] In one embodiment, an elastic sheet for an all-solid-state secondary battery is provided, the elastic sheet having a thickness of 100 μm to 500 μm and a strain of 10% or less in a vacuum environment of 0.1 MPa. An elastic sheet satisfying these properties can effectively alleviate stress due to thickness change during charge and discharge of an all-solid-state secondary battery, improve coulombic efficiency and life characteristics, and suppress misalignment of all-solid-state unit cells stacked in one direction.

[0050] The thickness of the elastic sheet is 100 μm to 500 μm, and for example, the thickness of the elastic sheet may be 300 μm, 100 μm, or 500 μm. For example, the thickness of the elastic sheet may vary depending on the position between a plurality of unit cells laminated in one direction.

[0051] The strain of the above elastic sheet may include, but is not limited to, the strain of the width of the elastic sheet in a vacuum environment of 0.1 MPa.

[0052] The elastic sheet may have a strain of 10% or less in a vacuum environment of 0.1 MPa. Here, the strain may refer to the change in width of the elastic sheet measured after positioning the elastic sheet from an atmospheric pressure of 45 degrees Celsius to a vacuum environment of 0.1 MPa. For example, the strain of the elastic sheet may be a value calculated using the following calculation formula 1.

[0053] [Calculation Formula 1]

[0054] Strain of elastic sheet (%) = {|(width of elastic sheet at atmospheric pressure) - (width of elastic sheet in a vacuum environment of 0.1 MPa)| / (width of elastic sheet at atmospheric pressure)} × 100

[0055] For example, in a vacuum environment of 0.1 MPa, the strain of the elastic sheet may be 10% or less when the thickness of the elastic sheet is 300 μm, 30% or less when the thickness of the elastic sheet is 100 μm, or 5% or less when the thickness of the elastic sheet is 500 μm.

[0056] When the elastic sheet satisfies the strain range above, it can effectively alleviate stress changes due to charge and discharge while providing appropriate compressive strength to the all-solid-state secondary battery, thereby improving the coulombic efficiency and life characteristics of the all-solid-state secondary battery, while suppressing misalignment of the all-solid-state unit cells stacked in one direction.

[0057] The above elastic sheet includes a polymer resin. Here, the type of the polymer resin is not particularly limited as long as the elastic sheet can satisfy the above-described properties, but may include, for example, polyacrylate, polyurethane, silicone, fluorinated polymer, polyether polyol, polyester polyol, polycarbonate polyol, copolymers thereof, or combinations thereof.

[0058] The above polyacrylate refers to a homopolymer or copolymer having an acrylic group, and the above polyurethane refers to a homopolymer or copolymer having a urethane group. The above silicone, also called a silicon resin, refers to a homopolymer or copolymer containing silicon, and the above fluorine-based polymer refers to a homopolymer or copolymer containing fluorine. These polymers can exhibit appropriate elasticity, modulus, and compressive strain, making them suitable for use as elastic sheets.

[0059] As the polymer resin, a polyether polyol for polyurethane can be used. The polyether polyol preferably has a functional group number of 2 to 4 and a number average molecular weight of 2,000 to 4,000.

[0060] In addition to the above polyether polyols, polyester polyols may be used. 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, 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-based 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. Those having 2 to 3 functional groups and a number average molecular weight of 500 or more and 1000 or less (or a hydroxyl value of 112 mgKOH / g or more and 224 mgKOH / g or less) are more preferable.

[0061] The polyacrylate may be derived from, for example, a C1 to C20 alkyl acrylate, a hydroxy C1 to C20 alkyl acrylate, or a combination thereof.

[0062] Here, C1 to C20 refer to the number of carbon atoms in the alkyl group, and may be, for example, C1 to C18, C1 to C15, C1 to C12, C1 to C10, C1 to C8, C1 to C5. Here, acrylate is a concept including acrylate and methacrylate.

[0063] The C1 to C20 alkyl acrylate may be, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylpentyl (meth)acrylate, 2-ethylheptyl (meth)acrylate, 2-ethylnonyl (meth)acrylate, 2-propylhexyl (meth)acrylate, and 2-propyloctyl (meth)acrylate, or a combination thereof.

[0064] The above hydroxy C1 to C20 alkyl acrylate may be, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, or a combination thereof.

[0065] For example, the acrylate 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 acrylate resin may exhibit appropriate adhesiveness and is advantageous in realizing excellent compressive strength, stress relaxation rate, and recovery rate.

[0066] The above acrylate resin may further include other repeating units derived from acrylic acid, an alkoxy group-containing acrylate, etc. In addition, the weight average molecular weight of the above acrylate resin may be from 400,000 to 2,000,000, but is not limited thereto.

[0067] The above elastic sheet may include foam. It may include a foam having the porosity of the elastic sheet.

[0068] The above elastic sheet may further include hollow particles in addition to the polymer resin.

[0069] The hollow particles described above are hollow 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.

[0070] 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.

[0071] 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.

[0072] The inorganic hollow particles may include, for example, glass, metal oxide, metal carbide, metal fluoride, or a combination 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 a combination thereof, and as an example, the inorganic hollow particles may be glass bubbles.

[0073] The organic hollow particles may include, for example, an acrylic resin, a vinyl chloride resin, a urea resin, a phenol resin, a rubber, or a combination thereof. In addition, 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.

[0074] The size (D50) of the hollow particles may be, for example, a micro size, and specifically, may be 2 ㎛ to 100 ㎛, 5 ㎛ to 90 ㎛, 10 ㎛ to 80 ㎛, or 20 ㎛ to 70 ㎛. Hollow particles having such a size are advantageous for making an elastic sheet in a foam form, and can lower the density while improving the compressive strength of the elastic sheet and improving the stress relaxation ability and resilience. Here, the size of the hollow particles may be expressed as an average particle diameter or a median particle diameter, and may mean the diameter (D50) of particles having a cumulative volume of 50% by volume in a particle size distribution as measured by a particle size analyzer.

[0075] The above elastic sheet may further include elastic particles in addition to the polymer resin. The elastic particles may be particles made of a polymer having elasticity, such as rubber. The elastic particles may increase the restoring force while maintaining the stress relaxation capacity of the polymer resin.

[0076] 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.

[0077] The elastic particles may comprise, for example, a polymer derived from natural rubber, alkyl acrylate, olefin, butadiene, isoprene, styrene, acrylonitrile, copolymers thereof, or a combination thereof. The elastic particles may have, for example, a glass transition temperature of -70°C to 0°C.

[0078] The above alkyl acrylate may 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 a combination thereof.

[0079] 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.

[0080] The elastic particles may, for example, have a core-shell structure, which is advantageous in exhibiting appropriate size and elasticity. The core and shell may each comprise, for example, polyalkyl acrylate. For example, the core may comprise polybutyl (meth)acrylate, and the shell may comprise polymethyl (meth)acrylate. In this case, the dispersion properties within the elastic sheet composition are excellent, and the compressive strength, stress relaxation strength, and resilience of the elastic sheet can be improved.

[0081] The elastic particles may be, for example, nano-sized. Specifically, the size (D50) of the elastic particles may be from 10 nm to 900 nm, for example from 10 nm to 700 nm, from 50 nm to 500 nm, or from 100 nm to 400 nm. Elastic particles satisfying such sizes have excellent dispersibility in the elastic sheet composition, and can increase the restoring force while maintaining the stress relaxation ability of the elastic sheet. Here, the size of the elastic particles may be expressed as an average particle diameter or a median particle diameter, and may mean the diameter (D50) of particles having a cumulative volume of 50% by volume in the particle size distribution as measured by a particle size analyzer.

[0082] The above elastic sheet may further include inorganic particles. In this case, the modulus and compressive strength of the elastic sheet can be improved while simultaneously improving the recovery rate.

[0083] The 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.

[0084] 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.

[0085] The average particle diameter of the above-mentioned inorganic particles may be 0.1 ㎛ to 2 ㎛, for example, 0.1 ㎛ to 1.5 ㎛, or 0.2 ㎛ to 1.0 ㎛. The above-mentioned average particle diameter is measured using a laser scattering particle size distribution meter, and may refer to the median particle diameter (D50) when 50% is accumulated from the small particle side in volume conversion.

[0086] The above elastic sheet may further contain suitable additives in addition to the aforementioned components, for example, an initiator, a crosslinking agent, a coupling agent, a foaming agent, etc. In addition, in order to manufacture an elastic sheet in a foam form, the elastic sheet may further contain an inert gas such as nitrogen or argon in addition to or together with the foaming agent.

[0087] Each additive may be included in an appropriate amount according to the purpose, and for example, may be included in an amount of 0.001 to 20 parts by weight based on 100 parts by weight of the polymer resin, for example, may be included in an amount of 0.01 to 10 parts by weight, 0.1 to 5 parts by weight, or 1 to 3 parts by weight.

[0088] solid electrolyte layer

[0089] In an all-solid-state secondary battery according to one embodiment, the solid electrolyte layer (120) may include an inorganic solid electrolyte such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

[0090] For example, the solid electrolyte layer (120) may include a sulfide-based solid electrolyte having excellent ion conductivity. The sulfide-based solid electrolyte particles include, for example, Li2S-P2S5, Li2S-P2S5--LiX (wherein 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.

[0091] Such sulfide-based solid electrolytes 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. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0092] Methods for mixing sulfur-containing raw materials for producing sulfide-based solid electrolytes include mechanical milling or the solution method. Mechanical milling involves placing the starting materials in a ball mill reactor and vigorously stirring them to finely atomize and mix them. Using the solution method, the starting 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.

[0093] According to one embodiment, a sulfide-based solid electrolyte 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 durability 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.

[0094] For example, the sulfide-based solid electrolyte may include an argyrodite-type sulfide. The argyrodite-type sulfide may be, for example, Li a Mb P c S d A e (wherein a, b, c, d, and e are all 0 or more and 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I) and can be expressed by the chemical formula, and a specific example is Li 7-x PS 6-x A x (x is 0.2 or more and 1.8 or less, and A is F, Cl, Br, or I) can be expressed by the chemical formula. The above argyrodite-type sulfide is specifically Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0095] Sulfide-based solid electrolytes containing these argyrodite-type sulfides have an ionic conductivity of 10 that of typical liquid electrolytes 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 the same can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0096] An argyrodite-type sulfide-based solid electrolyte can be manufactured, 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 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.

[0097] The solid electrolyte layer (120) may include an oxide-based inorganic solid electrolyte. The oxide-based inorganic solid electrolyte may be, 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 yTiO3, 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= Ta, Te, Nb, Zn, or Zr; x is an integer from 1 to 10), or mixtures thereof.

[0098] The above solid electrolyte is in the form of particles, and the average particle diameter (D50) of the particles may be 5.0 ㎛ or less, for example, 0.1 ㎛ to 5.0 ㎛, 0.5 ㎛ to 5.0 ㎛, 0.5 ㎛ to 4.0 ㎛, 0.5 ㎛ to 3.0 ㎛, 0.5 ㎛ to 2.0 ㎛, or 0.5 ㎛ to 1.0 ㎛. The solid electrolyte may be small particles having a size of 0.1 ㎛ to 1.9 ㎛, large particles having a size of 2.0 ㎛ to 5.0 ㎛, or a mixture thereof. 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 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 therefrom.

[0099] Meanwhile, the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (120) may be larger than the average particle diameter (D50) of the solid electrolyte included in the positive electrode (130). In this case, the energy density of the all-solid-state secondary battery can be maximized while increasing the mobility of lithium ions, thereby improving the overall performance. For example, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (130) may be 0.1 ㎛ to 1.9 ㎛, or 0.1 ㎛ to 1.0 ㎛, and the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (120) may be 2.0 ㎛ to 5.0 ㎛, or 2.0 ㎛ to 4.0 ㎛, or 2.5 ㎛ to 3.5 ㎛. When this particle size range is satisfied, the energy density of the all-solid-state secondary battery can be maximized, while the transfer of lithium ions can be facilitated, thereby suppressing resistance and improving the overall performance of the all-solid-state secondary battery.

[0100] The solid electrolyte layer (120) may further include a binder in addition to the solid electrolyte. The binder may 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, 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, or a combination thereof.

[0101] The solid electrolyte layer (120) can be formed by adding a solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent of the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the solid electrolyte layer formation process is widely known in the art, a detailed description thereof will be omitted.

[0102] The solid electrolyte layer (120) may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0103] 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.

[0104] The above lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0105] In addition, the lithium salt may be an imide-based one, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0106] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0107] The above ionic liquid may be a compound including a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) one or more anions selected from 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-.

[0108] 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.

[0109] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0110] cathode

[0111] An anode for an all-solid-state secondary battery includes 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.

[0112] The above 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.

[0113] 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.

[0114] As the above lithium metal alloy, an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0115] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and the Si-based negative electrode active material may be silicon, a silicon-carbon composite, or SiO. x (0 < x < 2), Si-Q alloy (wherein Q is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn-based negative electrode active materials include Sn, SnO2, Sn-R alloy (wherein R is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), and at least one of these may be mixed with SiO2 for use. The above elements Q and R may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0116] For example, the negative active material may include silicon-carbon composite particles. The average particle diameter (D50) of the silicon-carbon composite particles may be, for example, 0.5 μm to 20 μm. The average particle diameter (D50) is measured by a particle size analyzer and refers to the diameter of particles having a cumulative volume of 50% by volume in a particle size distribution. With respect to 100 wt% of the silicon-carbon composite particles, silicon may be included in an amount of 10 wt% to 60 wt% and carbon may be included in an amount of 40 wt% to 90 wt%. The silicon-carbon composite particles may include, for example, a core including silicon particles and a carbon coating layer positioned on a surface of the core. The average particle diameter (D50) of the silicon particles in the core may be, for example, 10 nm to 1 μm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon is SiO x (0 <x<2)로 표시될 수 있다. 또한, 상기 탄소 코팅층의 두께는 약 5 nm 내지 100 nm일 수 있다.

[0117] For example, the silicon-carbon composite particle may include a core including silicon particles and crystalline carbon, and a carbon coating layer located on the surface of the core and including amorphous carbon. For example, in the silicon-carbon composite particle, the amorphous carbon may not be present in the core but may be present only in the carbon coating layer. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof, and the amorphous carbon may be formed from coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or a polymer resin (phenol resin, furan resin, polyimide resin, etc.). At this time, the content of the crystalline carbon may be 10 wt% to 70 wt%, and the content of the amorphous carbon may be 20 wt% to 40 wt% with respect to 100 wt% of the silicon-carbon composite particle.

[0118] In the above silicon-carbon composite particle, the core may include a void in the central portion. The radius of the void may be 30% to 50% of the radius of the silicon-carbon composite particle.

[0119] The silicon-carbon composite particles described above can effectively suppress problems such as volume expansion, structural collapse, or particle crushing due to charge and discharge, thereby preventing the phenomenon of conductive path disconnection, realizing high capacity and high efficiency, and are advantageous for use under high voltage or fast charging conditions.

[0120] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material. When the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material are used in combination, the mixing ratio can be 1:99 to 90:10 by weight.

[0121] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0122] In one embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. In addition, when the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0123] 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 an insoluble binder, a water-soluble binder, or a combination thereof.

[0124] The above-mentioned non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0125] The water-soluble binder may be a rubber-based binder or a polymer resin binder. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0126] When a water-soluble binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity as a type of thickener 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. The amount of the thickener used may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0127] The above conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, any material that does not cause a chemical change and is electronically conductive can be used. Examples of conductive materials that can be used 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 including copper, nickel, aluminum, silver, etc. and in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0128] The negative electrode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0129] 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.

[0130] FIG. 2 is a cross-sectional view showing an all-solid-state secondary battery according to another embodiment including a precipitated negative electrode.

[0131] Referring to FIG. 2, a precipitated negative electrode (140) of a plurality of unit cells (101) stacked in one direction may include a negative electrode current collector (141) and a negative electrode coating layer (142) positioned on the current collector. An all-solid-state secondary battery having such a precipitated negative electrode (140) starts initial charging in a state in which no negative electrode active material is present, and when charging, a high-density lithium metal is precipitated or deposited between the negative electrode current collector (141) and the negative electrode coating layer (142), or on the negative electrode coating layer (142), to form a lithium metal layer (143), which can serve 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 (140) may include, for example, a negative electrode current collector (141), a lithium metal layer (143) positioned on the negative electrode current collector (141), and a negative electrode coating layer (142) positioned on the lithium metal layer (143). The lithium metal layer (143) may refer to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may include a metal layer, a lithium layer, a lithium deposition layer, or a negative electrode active material layer.

[0132] The above-mentioned cathode coating layer (142) may be referred to as a lithium electrodeposition induction layer or a cathode catalyst layer, and may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0133] 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 type 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 (D50) thereof may be about 4 μm or less, and may be, for example, 10 nm to 4 μm.

[0134] 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.

[0135] When the above-described negative electrode coating layer (142) 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 (142) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0136] The above-described cathode coating layer (142) 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. For example, the above-described cathode coating layer (142) may include a composite in which a lithium-philic metal is supported on amorphous carbon.

[0137] The above cathode coating layer (142) may further include a binder, and the binder may be, for example, a conductive binder. In addition, the above cathode coating layer (142) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0138] The thickness of the cathode coating layer (142) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0139] The above-described precipitated negative electrode (140) may further include, for example, a thin film between the current collector, which is the surface of 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 precipitation form of the lithium metal layer (143) 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.

[0140] The lithium metal layer (143) 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.

[0141] The thickness of the lithium metal layer (143) 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 (143) 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.

[0142] When such a precipitation-type cathode is applied, the cathode coating layer (142) can play a role in protecting the lithium metal layer (143) 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.

[0143] anode

[0144] In one embodiment, the 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 a solid electrolyte, and may optionally include a binder and / or a conductive material.

[0145] positive electrode active material

[0146] The above-mentioned positive electrode active material can be applied without limitation as long as it is generally used in all-solid-state secondary batteries. For example, the above-mentioned positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0147] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0148] 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);

[0149] Li a E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0150] Li a E 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0151] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0152] Li a Ni 1-b-c Co b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0153] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0154] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0155] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0156] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0157] Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0158] Li a Ni b Co c Mrd G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0159] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0160] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0161] Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0162] Li a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0163] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0164] QO2; QS2; LiQS2;

[0165] V2O5; LiV2O5;

[0166] LiZO2;

[0167] LiNiVO4;

[0168] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0169] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0170] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0171] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0172] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate (LFP).

[0173] The positive electrode 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.

[0174] [Chemical Formula 11]

[0175] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0176] 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.

[0177] 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.

[0178] [Chemical Formula 12]

[0179] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0180] 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.

[0181] [Chemical Formula 13]

[0182] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0183] 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.

[0184] [Chemical Formula 14]

[0185] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0186] 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.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] The positive electrode active material may be included in an amount of 55 wt% to 99 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%.

[0191] solid electrolyte

[0192] The solid electrolyte included in the positive electrode active material layer may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof, and may be, for example, an argyrodite-type sulfide-based solid electrolyte. Since the solid electrolyte is as described above, a detailed description thereof will be omitted.

[0193] With respect to 100 wt% of the above 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%.

[0194] In addition, in the positive electrode active material layer, 65 wt% to 99 wt% of the positive electrode active material and 1 wt% to 35 wt% of the solid electrolyte may be included based on the total weight of the positive electrode active material and the solid electrolyte, for example, 80 wt% to 90 wt% of the positive electrode active material and 10 wt% to 20 wt% of the solid electrolyte may be included. When the solid electrolyte is included in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0195] bookbinder

[0196] 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, and representative examples thereof 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, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0197] The content of the binder in the positive electrode active material layer may be approximately 0.1 wt% to 5 wt% with respect to 100 wt% of the positive electrode active material layer.

[0198] Challenge

[0199] The above-described positive electrode active material layer may further include a conductive material. The conductive material is used to provide conductivity to the electrode, and any material that does not cause a chemical change and is electronically conductive in the battery to be formed may be used. Examples of conductive materials that may be used include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0200] The content of the conductive material in the positive electrode active material layer may be 0 wt% to 3 wt%, 0.01 wt% to 2 wt%, or 0.1 wt% to 1 wt% with respect to 100 wt% of the positive electrode active material layer.

[0201] Aluminum foil may be used as the positive electrode current collector, but is not limited thereto.

[0202] The above-mentioned all-solid-state secondary battery may be a unit battery 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 these structures are repeated.

[0203] 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 requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0204] Experimental examples and comparative examples of the present invention are described below. The following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0205] Experimental Example 1

[0206] 1. Manufacturing of elastic sheets

[0207] 4-Hydroxybutyl acrylate (4-HBA, Osaka Organic Chemical Co.), 2-ethylhexyl acrylate (2-EHA, LG Chemical Co.), and isobornyl acrylate (IBOA, Osaka organic chemical) were mixed in a weight ratio of 25:65:10, 0.01 part by weight of a photoinitiator (Icacure 651) 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 was partially polymerized by irradiating it with ultraviolet rays for several minutes using a lamp to produce an acrylate polymer resin.

[0208] An organic nanoparticle is prepared as an elastic particle by an emulsion polymerization method, which is a core-shell particle composed of 70 wt% of a polybutylacrylate core and 30 wt% of a polymethylmethacrylate shell, and has an average particle diameter of 200 nm.

[0209] 100 parts by weight of the prepared acrylate polymer resin, 2 parts by weight of the elastic particles, and 0.01 part by weight of an initiator (Irgacure651) were mixed in a reactor. 0.3 parts by weight of the initiator (Irgacure651), 0.1 parts by weight of hexanediol diacrylate as a crosslinking agent, and hollow particles (glass bubbles; 3M) were added to the viscous liquid. TM An elastic sheet composition having adhesiveness was prepared by mixing 4 parts by weight of K1 (median particle size 65 ㎛) and 0.1 part by weight of fumed silica (AEROSIL 200).

[0210] The above elastic sheet composition is applied between polyethylene terephthalate (PET) films, which are release films, and exposed to ultraviolet light at 2000 mJ / cm 2 By investigating the amount of light, an elastic sheet bonded onto a PET film was manufactured. The thickness of the elastic sheet (Sheet A) according to the manufactured experimental example 1 is 300㎛, and the strain is 2%, which is less than 10% in a vacuum environment of 0.1MPa.

[0211] 2. Manufacturing of the anode

[0212] LiNi coated with Li2O-ZrO2 0.8 Co 0.15 Mn 0.05 A positive electrode composition was prepared by mixing 85 wt% of an O2 positive electrode 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 positive electrode composition was coated on a positive electrode current collector using a bar coater, and dried and rolled to prepare a positive electrode.

[0213] 3. Manufacturing of solid electrolyte layer

[0214] A slurry was prepared by adding an argyrodite-type solid electrolyte Li6PS5Cl (D50=3㎛) to a binder solution prepared by dissolving an acrylic binder (SX-A334, Zeon) in an isobutyl isobutyrate (IBIB) solvent and stirring the solution. The slurry contained 98.5 wt% of the solid electrolyte and 1.5 wt% of the 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.

[0215] 4. Manufacturing of the cathode

[0216] An Ag / C composite was prepared by mixing carbon black having a primary particle size (D50) of approximately 30 nm and silver (Ag) having an average particle size (D50) of approximately 60 nm in a weight ratio of 3:1, and 0.25 g of the composite 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, thereby preparing a deposition-type negative electrode in which a negative electrode coating layer was formed on the current collector.

[0217] 5. Manufacturing of all-solid-state batteries

[0218] A plurality of unit cells stacked in one direction are manufactured by stacking in the order of negative electrode / solid electrolyte / positive electrode / solid electrolyte / negative electrode. The unit cells are placed inside a case including an aluminum case laminate film, etc., and a vacuum environment of 0.1 MPa is formed inside the case and then pressurized to manufacture an all-solid-state secondary battery unit cell. The aluminum case is unpacked and the stacked cells are stacked in the order of elastic sheet / negative electrode / solid electrolyte / positive electrode / solid electrolyte / negative electrode / elastic sheet / negative electrode / solid electrolyte / negative electrode / elastic sheet. Afterwards, a vacuum environment of 0.1 MPa is formed inside the aluminum laminate film to house the stacked cells, thereby manufacturing an all-solid-state secondary battery.

[0219] The thickness of the elastic sheet (Sheet A) according to Experimental Example 1 is 300㎛, and the strain of the elastic sheet in a vacuum environment of 0.1MPa inside the case is 2%, which is less than 10%.

[0220] Experimental Example 2

[0221] An elastic sheet and an all-solid-state secondary battery according to Experimental Example 2 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Sheet B) according to Experimental Example 2 is 300 μm, and the strain of the elastic sheet in a vacuum environment of 0.1 MPa inside the case is 3%, which is less than 10%. Experimental Example 2 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0222] Experimental Example 3

[0223] An elastic sheet and an all-solid-state secondary battery according to Experimental Example 3 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Sheet C) according to Experimental Example 3 is 300 μm, and the strain of the elastic sheet is 10%, which is less than 10%, when the inside of the case is in a vacuum environment of 0.1 MPa. Experimental Example 3 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0224] Comparative Example 1

[0225] An elastic sheet and an all-solid-state secondary battery according to Comparative Example 1 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Comparative Example 1) according to Comparative Example 1 is 300 μm, and the strain of the elastic sheet is 16%, which is more than 10%, in a vacuum environment of 0.1 MPa inside the case. Comparative Example 1 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0226] Experimental Results 1

[0227] Figure 3 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Examples 1, 2, 3, and Comparative Example 1.

[0228] Referring to FIG. 3, in each of the all-solid-state secondary batteries according to Experimental Example 1 (Sheet A), Experimental Example 2 (Sheet B), Experimental Example 3 (Sheet C) and Comparative Example 1, it was confirmed whether a plurality of unit cells stacked in one direction in a vacuum environment of 0.1 MPa were positioned within the alignment tolerance.

[0229] The all-solid-state secondary batteries according to Experimental Example 1 (Sheet A), Experimental Example 2 (Sheet B), and Experimental Example 3 (Sheet C) have an elastic sheet thickness of 300 ㎛ and satisfy the numerical limitation that the strain of the elastic sheet is 10% or less in a vacuum environment of 0.1 MPa, so that multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa are positioned within the alignment tolerance.

[0230] In contrast, the all-solid-state secondary battery according to Comparative Example 1 has an elastic sheet thickness of 300 ㎛ and a strain of the elastic sheet of 16%, which is more than 10% in a vacuum environment of 0.1 MPa, so that the alignment misalignment of the multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa occurred due to the deformation of the elastic sheet placed therebetween, thereby exceeding the alignment tolerance.

[0231] According to Experimental Results 1, in order to suppress the breakage of the all-solid-state unit cell and improve the charge / discharge efficiency and life characteristics of the all-solid-state secondary battery by alleviating the stress transmitted to the all-solid-state unit cell and the stress generated in the all-solid-state unit cell during repeated charge / discharge, and at the same time suppress the misalignment of the all-solid-state unit cells stacked in one direction, the numerical limit configuration in which the thickness of the elastic sheet is 300㎛ and the strain of the elastic sheet is 10% or less in a vacuum environment of 0.1 MPa was confirmed to have a critical significance in that the upper limit can be confirmed to be the critical value through Experimental Example 1 (Sheet A), Experimental Example 2 (Sheet B), Experimental Example 3 (Sheet C), and Comparative Example 1 with reference to FIG. 3.

[0232] For example, when the strain of the elastic sheet is less than 1% in a vacuum environment of 0.1 MPa, the stress relaxation effect on multiple unit cells due to deformation of the elastic sheet may be reduced.

[0233] Example 4

[0234] An elastic sheet and an all-solid-state secondary battery according to Experimental Example 4 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Sheet D) according to Experimental Example 4 is 100 μm, and the strain of the elastic sheet is 30%, which is less than 30%, when the inside of the case is in a vacuum environment of 0.1 MPa. Experimental Example 4 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0235] Comparative Example 2

[0236] An elastic sheet and an all-solid-state secondary battery according to Comparative Example 2 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Comparative Example 2) according to Comparative Example 2 is 100 μm, and the strain of the elastic sheet is 50%, which is more than 30%, in a vacuum environment of 0.1 MPa inside the case. Comparative Example 2 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0237] Experimental Results 2

[0238] Figure 4 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Example 4 and Comparative Example 2.

[0239] Referring to Fig. 4, in each of the all-solid-state secondary batteries according to Experimental Example 4 (Sheet D) and Comparative Example 2, it was confirmed whether a plurality of unit cells stacked in one direction in a vacuum environment of 0.1 MPa were positioned within the alignment tolerance.

[0240] The all-solid-state secondary battery according to Experimental Example 4 (Sheet D) has an elastic sheet thickness of 100 ㎛ and satisfies the numerical limitation that the strain of the elastic sheet is 30% or less in a vacuum environment of 0.1 MPa, so that multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa are positioned within the alignment tolerance.

[0241] In contrast, the all-solid-state secondary battery according to Comparative Example 2 has an elastic sheet thickness of 100 ㎛ and a strain of the elastic sheet of 50%, which is more than 30% in a vacuum environment of 0.1 MPa, so that the alignment misalignment of the multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa occurred due to the deformation of the elastic sheet placed therebetween, thereby exceeding the alignment tolerance.

[0242] According to Experimental Results 2, in order to suppress the breakage of the all-solid-state unit cell and improve the charge / discharge efficiency and life characteristics of the all-solid-state secondary battery by alleviating the stress transmitted to the all-solid-state unit cell and the stress generated in the all-solid-state unit cell during repeated charge / discharge, and at the same time suppress the misalignment of the all-solid-state unit cells stacked in one direction, the numerically limited configuration in which the thickness of the elastic sheet is 100 ㎛ and the strain of the elastic sheet is 30% or less in a vacuum environment of 0.1 MPa was confirmed to have a critical significance in that the upper limit can be confirmed to be the critical value through Experimental Example 4 (Sheet D) and Comparative Example 2 with reference to FIG. 4.

[0243] Example 5

[0244] An elastic sheet and an all-solid-state secondary battery according to Experimental Example 5 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Sheet E) according to Experimental Example 5 is 500 μm, and the strain of the elastic sheet is 5%, which is less than 5%, when the inside of the case is in a vacuum environment of 0.1 MPa. Experimental Example 5 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0245] Comparative Example 3

[0246] An elastic sheet and an all-solid-state secondary battery according to Comparative Example 3 were manufactured using substantially the same method as Experimental Example 1. The thickness of the elastic sheet (Comparative Example 3) according to Comparative Example 3 is 500 μm, and the strain of the elastic sheet in a vacuum environment of 0.1 MPa inside the case is 10%, which is more than 5%. Comparative Example 3 can manufacture an elastic sheet by increasing the porosity of the elastic sheet compared to Experimental Example 1, but is not limited thereto.

[0247] Experimental Results 3

[0248] Figure 5 is a table showing the results of an experiment that confirmed the alignment misalignment results of Experimental Example 5 and Comparative Example 3.

[0249] Referring to Fig. 5, in each of the all-solid-state secondary batteries according to Experimental Example 5 (Sheet E) and Comparative Example 3, it was confirmed whether a plurality of unit cells stacked in one direction in a vacuum environment of 0.1 MPa were positioned within the alignment tolerance.

[0250] The all-solid-state secondary battery according to Experimental Example 5 (Sheet E) has an elastic sheet thickness of 500 ㎛ and satisfies the numerical limitation that the strain of the elastic sheet is 5% or less in a vacuum environment of 0.1 MPa, so that multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa are positioned within the alignment tolerance.

[0251] In contrast, the all-solid-state secondary battery according to Comparative Example 3 has an elastic sheet thickness of 500 ㎛, and since the strain of the elastic sheet in a vacuum environment of 0.1 MPa is 10%, which is more than 5%, the alignment misalignment of the multiple unit cells stacked in one direction in a vacuum environment of 0.1 MPa occurred due to the deformation of the elastic sheet placed therebetween, and thus the alignment tolerance was exceeded.

[0252] According to Experimental Results 3, in order to suppress the breakage of the all-solid-state unit cell and improve the charge / discharge efficiency and life characteristics of the all-solid-state secondary battery by alleviating the stress transmitted to the all-solid-state unit cell and the stress generated in the all-solid-state unit cell during repeated charge / discharge, and at the same time suppress the misalignment of the all-solid-state unit cells stacked in one direction, the numerical limit configuration in which the thickness of the elastic sheet is 500㎛ and the strain of the elastic sheet is 5% or less in a vacuum environment of 0.1 MPa was confirmed to have a critical significance in that the upper limit can be confirmed to be the critical value through Experimental Example 5 (Sheet E) and Comparative Example 3 with reference to FIG. 5.

[0253] According to the above-described Experimental Results 1, 2, and 3, in order to suppress the breakage of the all-solid-state unit cell and improve the charge-discharge efficiency and lifespan characteristics of the all-solid-state secondary battery by alleviating the stress transmitted to the all-solid-state unit cell and the stress generated in the all-solid-state unit cell during repeated charge and discharge, and at the same time suppress the misalignment of the all-solid-state unit cells stacked in one direction, it was confirmed that the numerically limited configuration in which the thickness of the elastic sheet is 100 ㎛ to 500 ㎛ and the strain of the elastic sheet is 10% or less in a vacuum environment of 0.1 MPa has a critical significance in that the upper limit is the critical value through Experimental Examples 1 (Sheet A), 2 (Sheet B), 3 (Sheet C), 4 (Sheet D), 5 (Sheet E), and Comparative Examples 1, 2, and 3.

[0254] 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.

[0255] [Explanation of symbols]

[0256] 100: Unit cell 130: Anode

[0257] 131: Cathode current collector 132: Cathode active material layer

[0258] 120: Solid electrolyte layer 110: Cathode

[0259] 111: Negative current collector 112: Negative active material layer

[0260] 140: Precipitation type cathode 143: Lithium metal layer

[0261] 142: Cathode coating layer 200: Elastic layer

Claims

1. An elastic sheet for an all-solid-state secondary battery having a thickness of 100 ㎛ to 500 ㎛ and a strain of 10% or less in a vacuum environment of 0.1 MPa.

2. In paragraph 1, The above-mentioned all-solid-state secondary battery elastic sheet has a thickness of 300 μm.

3. In paragraph 1, The above strain includes the strain of the width of the elastic sheet for an all-solid-state secondary battery.

4. In paragraph 1, The above-mentioned elastic sheet for an all-solid-state secondary battery is an elastic sheet for an all-solid-state secondary battery containing foam.

5. In paragraph 1, The above-mentioned elastic sheet for an all-solid-state secondary battery contains a polymer resin, The above polymer resin is an elastic sheet for an all-solid-state secondary battery including polyacrylate, polyurethane, silicone, fluorine-based polymer, polyether polyol, polyester polyol, polycarbonate polyol, copolymers thereof, or a combination thereof.

6. In paragraph 5, The above polyacrylate is an elastic sheet for an all-solid-state secondary battery comprising a C1 to C20 alkyl acrylate, a hydroxy C1 to C20 alkyl acrylate, or a combination thereof.

7. In paragraph 5, The above all-solid-state secondary battery elastic sheet further comprises hollow particles.

8. In paragraph 7, An elastic sheet for an all-solid-state battery, wherein the hollow particles are contained in an amount of 1 to 8 parts by weight based on 100 parts by weight of the polymer resin.

9. In paragraph 7, The above hollow particles are inorganic hollow particles, organic hollow particles, or a combination thereof, The above inorganic hollow particles include glass, metal oxide, metal carbide, metal fluoride, or a combination thereof, The above organic hollow particles are elastic sheets for all-solid-state batteries comprising acrylic resin, vinyl chloride resin, urea resin, phenol resin, or a combination thereof.

10. In paragraph 7, An elastic sheet for an all-solid-state battery, wherein the average particle diameter (D50) of the hollow particles is 2 ㎛ to 100 ㎛.

11. In paragraph 5, The above-mentioned elastic sheet for an all-solid-state secondary battery further contains elastic particles, The above elastic particles are an elastic sheet for an all-solid-state secondary battery comprising alkyl acrylate, olefin, butadiene, isoprene, styrene, acrylonitrile, copolymers thereof, or a combination thereof.

12. In Article 11, 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 polymer resin.

13. In Article 11, An elastic sheet for an all-solid-state secondary battery, wherein the average particle diameter (D50) of the elastic particles is 10 nm to 900 nm.

14. In paragraph 5, 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 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 a combination thereof.

15. In paragraph 14, 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 polymer resin.

16. In paragraph 5, 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, an inert gas, or a combination thereof.

17. An elastic sheet for an all-solid-state secondary battery having a thickness of 100 μm and a strain of 30% or less in a vacuum environment of 0.1 MPa.

18. An elastic sheet for an all-solid-state secondary battery having a thickness of 500 μm and a strain of 5% or less in a vacuum environment of 0.1 MPa.

19. A plurality of unit cells including solid electrolyte layers laminated in one direction; and An elastic sheet for an all-solid-state secondary battery according to any one of claims 1 to 18, positioned between the plurality of unit cells An all-solid-state secondary battery comprising:

20. In paragraph 19, An all-solid-state secondary battery further comprising a case that houses the plurality of unit cells and the elastic sheet for the all-solid-state secondary battery inside in a vacuum environment of 0.1 MPa.

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