Cell structure and all-solid-state rechargeable battery

Abstract

The present invention relates to a battery structure of a bi-cell structure and an all-solid-state rechargeable battery comprising same, the battery structure including a positive electrode current collector, positive electrode active material layers positioned on both surfaces of the positive electrode current collector, solid electrolyte layers positioned on the positive electrode active material layers, and negative electrodes positioned on the solid electrolyte layers, wherein the positive electrode current collector includes a resin sheet and metal films positioned on both surfaces of the resin sheet.

Description

Battery structure and all-solid-state secondary battery

[0001] It relates to a battery structure and an all-solid-state secondary battery.

[0002] Lithium secondary batteries, which boast high energy density and portability, are primarily used as power sources for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, research is also actively 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] By minimizing the concentration of stress that occurs due to uneven thickness of each element within the battery structure, the performance and reliability of the all-solid-state secondary battery are improved, and in addition, the safety of the all-solid-state secondary battery is enhanced by effectively preventing short-circuiting of the battery in the event of problems such as penetration or collision.

[0005] In one embodiment, a battery structure having a bi-cell structure is provided, which includes a positive electrode current collector, a positive electrode active material layer positioned on both sides of the positive electrode current collector, a solid electrolyte layer positioned on the positive electrode active material layer, and a negative electrode positioned on the solid electrolyte layer, wherein the positive electrode current collector includes a resin sheet and a metal film positioned on both sides of the resin sheet.

[0006] In another embodiment, an all-solid-state secondary battery is provided in which two or more of the above battery structures are stacked.

[0007] According to one embodiment, a battery structure can improve the overall performance and reliability, including the lifespan characteristics, of an all-solid-state secondary battery by minimizing the concentration of stress due to repeated charge and discharge cycles. Furthermore, to resolve the stress concentration problem, it is possible to omit elastic sheets interposed between battery structures or at the outermost layer, thereby reducing the number of components and process steps within the battery and improving fire safety. Furthermore, the battery structure can effectively prevent short circuits when the battery is penetrated or impacted by a sharp object, thereby further enhancing the safety of the battery.

[0008] Figures 1 and 2 are cross-sectional views schematically showing a battery structure according to one embodiment.

[0009] Below, specific implementation examples are described in detail to facilitate their implementation by those skilled in the art. However, the present invention may be implemented in various different forms and is not limited to the implementation examples described herein.

[0010] 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.

[0011] Here, “combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0012] 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.

[0013] To clearly illustrate various layers and regions in the drawings, their thicknesses are enlarged, and similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" or "on" another element, this includes not only the case where it is "directly over" the other element, but also the case where there are other elements in between. Conversely, when an element is said to be "directly over" another element, it means that there are no other elements in between.

[0014] 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.

[0015] The average particle size can be measured by methods well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with transmission electron microscope images or scanning electron microscope images. Alternatively, the average particle size can be obtained by measuring using dynamic light scattering, performing data analysis, counting the number of particles for each particle size range, and calculating from the counted number. Unless otherwise defined, the average particle size is the diameter (D) of the particles in the particle size distribution that have a cumulative volume of 50% by volume. 50 ) can mean. In addition, unless otherwise defined, the average particle size is obtained by measuring the size (diameter or length of major axis) of about 20 particles randomly in a scanning electron microscope image to obtain a particle size distribution, and the diameter (D) of the particle having a cumulative volume of 50% by volume in the particle size distribution 50) may be taken as the average particle diameter.

[0016] Here, “or” is not interpreted in an exclusive sense, for example, “A or B” is interpreted to include A, B, A+B, etc.

[0017] “Metal” is interpreted as a concept that includes common metals, transition metals, and metalloids (semi-metals).

[0018] Battery structure

[0019] Fig. 1 is a cross-sectional view of a battery structure according to one embodiment. Referring to Fig. 1, the battery structure (100) has a bi-cell structure including a positive electrode current collector, a positive electrode active material layer (203) positioned on both sides of the positive electrode current collector, a solid electrolyte layer (300) positioned on the positive electrode active material layer, and a negative electrode (400) positioned on the solid electrolyte layer, and the positive electrode current collector is characterized by including a resin sheet (201) and a metal film (202) positioned on both sides of the resin sheet. The battery structure may be referred to as a bi-cell structure for an all-solid-state secondary battery.

[0020] All-solid-state secondary batteries experience thickness variations across different regions within a single bi-cell structure due to various factors, including thickness variations between the positive and negative electrodes, thickness variations during structural assembly, and compression variations across regions after the high-pressure press process. These variations can lead to uneven contact between cell structures or between elements within a cell structure during repeated expansion and contraction during charging and discharging, potentially leading to stress concentrations in specific regions. These areas of concentrated stress can lead to cracks and other damage, while areas lacking stress can develop voids, ultimately reducing the battery's lifespan. To address this issue, existing techniques have been proposed to alleviate stress concentration by interposing elastic sheets between or on the outermost layer of cell structures. However, inserting elastic sheets increases the number of components and process steps, leading to increased defects and higher production costs. Furthermore, if heat is generated due to penetration or impact in the all-solid-state secondary battery, the elastic sheets can impede heat dissipation, potentially causing fire and compromising battery safety.

[0021] In one embodiment, a resin-metal composite substrate in which a metal film is coated on both sides of a resin sheet is introduced instead of a conventional metal substrate as a positive electrode collector located at the center of a bi-cell structure. First, the stress concentration phenomenon during the charge and discharge process is minimized due to the elasticity of the positive electrode collector itself, thereby improving the life characteristics and reliability of the all-solid-state secondary battery. Second, the existing elastic sheet can be omitted, thereby reducing the number of parts and process steps. Third, the battery safety can be ensured by effectively preventing a short circuit in the event of a problem such as penetration. For example, even if the battery is penetrated by a sharp object, the metal film in the positive electrode collector according to one embodiment is very thin, so that the burr is small compared to the conventional metal substrate (10 to 50 ㎛ in thickness), and the elastic resin sheet blocks electrical conduction, which can drastically reduce the possibility of a short circuit due to contact between the positive and negative electrodes, thereby enhancing the safety of the all-solid-state secondary battery.

[0022] positive current collector

[0023] A cathode current collector according to one embodiment includes a resin sheet and a metal film positioned on both sides of the resin sheet.

[0024] resin sheet

[0025] The resin sheet can be applied without limitation as long as it is in the form of a sheet made of a polymer resin and has elasticity. The thickness of the resin sheet is not particularly limited, but may be approximately 1 ㎛ to 100 ㎛, for example, 1 ㎛ to 80 ㎛, 1 ㎛ to 60 ㎛, 3 ㎛ to 50 ㎛, 5 ㎛ to 30 ㎛, or 5 ㎛ to 20 ㎛. Generally, the thickness of the elastic sheet is about 200 ㎛ or more, but in the positive electrode current collector according to one embodiment, the resin sheet may have a thickness thinner than this, and even with a thin thickness, it can suppress stress concentration and also realize a thin film of the battery.

[0026] The resin sheet may include, for example, polyethylene, polypropylene, polyamide, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyacrylonitrile, poly(meth)acrylate, polymethyl(meth)acrylate, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl chloride, polyurethane, epoxy resin, nylon resin, acrylic resin, polystyrene, polyethylene oxide, polyvinyl alcohol, silicone resin, styrene-butadiene-rubber, acrylonitrile-butadiene-rubber, hydrogenated nitrile-butadiene-rubber, copolymers thereof, or mixtures thereof.

[0027] In addition to the polymer resin described above, the resin sheet may further include inorganic particles, elastic particles, an initiator, a crosslinking agent, a coupling agent, a stabilizer, etc.

[0028] metal film

[0029] The metal film is positioned on both sides of the resin sheet and substantially plays the role of current collector, and may be a portion in contact with the positive electrode active material layer. The thickness of the metal film is not particularly limited, but may be, for example, 10 nm to 2 ㎛, 10 nm to 1 ㎛, 10 nm to 900 nm, 10 nm to 600 nm, 50 nm to 500 nm, 50 nm to 200 nm, or 10 nm to 100 nm. Generally, the metal substrate used as the positive electrode current collector has a thickness of about 10 to 50 ㎛, but the thickness of the metal film of the positive electrode current collector according to one embodiment can be said to be much thinner than that, and accordingly, compared to the existing metal substrate, the burr is smaller in an abnormal situation such as penetration or impact, and the problem of a battery short circuit caused by this can be effectively suppressed.

[0030] The metal film may include, for example, Al, Cu, Fe, Ni, SUS, Ti, or a combination thereof.

[0031] The metal film can be coated on both sides of the resin sheet by various coating methods, for example, it can be coated by a deposition method, in which case it can be called a metal deposition film.

[0032] The overall thickness of the positive electrode current collector including the resin sheet and the metal film may be from 1.02 μm to 104 μm, for example from 1.1 μm to 100 μm, from 5 μm to 80 μm, from 5 μm to 50 μm, from 5 μm to 30 μm, or from 10 μm to 20 μm.

[0033] positive electrode active material layer

[0034] The cathode active material layer includes a cathode active material and a solid electrolyte, and for example, includes a cathode active material containing a transition metal composite oxide, and a sulfide-based solid electrolyte, and may optionally include a binder and / or a conductive material.

[0035] A compound capable of reversible intercalation and deintercalation of lithium (a lithiated intercalation compound) can be used as a cathode active material. Specifically, one or more of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used.

[0036] The above composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel-based oxide, lithium cobalt-based oxide, lithium manganese-based oxide, lithium iron phosphate-based compound, cobalt-free nickel-manganese-based oxide, lithium-rich layered oxide, or a combination thereof.

[0037] For example, the cathode active material may be a high-nickel cathode active material in which the nickel content is 80 mol% or more based on 100 mol% of metals excluding lithium in a lithium transition metal composite oxide. The nickel content in the high-nickel cathode active material may be 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more, and 99 mol% or less based on 100 mol% of metals excluding lithium. The high-nickel cathode active material can realize high capacity and thus can be applied to high-capacity, high-density lithium secondary batteries.

[0038] As a more specific example, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Mn 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤0.5, 0 < α < 2);Li a Ni 1-b-c Mn b X c O 2-α D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 < α < 2);Li a Ni b Co c L 1 d G eO2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.1);; Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4(0.90 ≤ a ≤1.8, 0.001 ≤ b ≤ 0.1); Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); Li a FePO4(0.90 ≤ a ≤ 1.8)

[0039] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; Z is Cr, V, Fe, Sc, Y, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0040] The cathode active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 11, a lithium cobalt-based oxide represented by the following chemical formula 12, a lithium iron phosphate-based compound represented by the following chemical formula 13, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 14, or a combination thereof.

[0041] [Chemical Formula 11]

[0042] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0043] 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.

[0044] 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.

[0045] [Chemical Formula 12]

[0046] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0047] In the above chemical formula 12, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0048] [Chemical Formula 13]

[0049] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0050] 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.

[0051] [Chemical Formula 14]

[0052] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0053] 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.

[0054] The average particle diameter (D) of the above positive electrode active material 50 ) may be 1 ㎛ to 25 ㎛, for example, 3 ㎛ to 25 ㎛, 1 ㎛ to 20 ㎛, 1 ㎛ to 18 ㎛, 3 ㎛ to 15 ㎛, or 5 ㎛ to 15 ㎛. For example, the positive electrode active material may have an average particle diameter (D 50 ) with small particles of 1 ㎛ to 9 ㎛ and an average particle diameter (D 50 ) may include particles having a particle size range of 10 ㎛ to 25 ㎛. The positive electrode active material having such a particle size range can be harmoniously mixed with other components in the positive electrode active material layer and can realize high capacity and high energy density. Here, the average particle size is obtained by selecting 20 or so random particles from a scanning electron microscope image of the positive electrode active material, measuring their particle sizes (diameter, or major axis, or major axis length), and then obtaining a particle size distribution, and in the particle size distribution, the diameter (D) of the particles having a cumulative volume of 50% by volume 50 ) may be taken as the average particle diameter.

[0055] 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.

[0056] 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.

[0057] The positive electrode active material may be included in an amount of 55 wt% to 99.5 wt% based on 100 wt% of the positive electrode active material layer, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0058] solid electrolyte

[0059] In a battery structure according to one embodiment, the positive electrode active material layer includes a solid electrolyte, and may include, for example, a sulfide-based solid electrolyte, and specifically, an argyrodite-type sulfide-based solid electrolyte. Details regarding the solid electrolyte will be described in detail later in the section on the solid electrolyte layer.

[0060] For 100 wt% of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%.

[0061] In the positive electrode active material layer, the positive electrode active material may be comprised in an amount of 65 to 99 wt% and the solid electrolyte in an amount of 1 to 35 wt%, based on 100 wt% of the total of the positive electrode active material and the solid electrolyte, for example, the positive electrode active material may be comprised in an amount of 80 to 90 wt% and the solid electrolyte in an amount of 10 to 20 wt%. When the solid electrolyte is comprised in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state secondary battery can be improved without reducing the capacity.

[0062] Meanwhile, the average particle diameter (D) of the sulfide-based solid electrolyte in the positive electrode active material layer 50 ) is the average particle diameter (D) of the sulfide-based solid electrolyte in the solid electrolyte layer described later. 50 ) may be smaller than the average particle diameter (D) of the sulfide-based solid electrolyte in the positive electrode active material layer. 50 ) may be 0.1 ㎛ to 1.9 ㎛, or 0.5 ㎛ to 1.5 ㎛, and the average particle diameter (D) of the sulfide-based solid electrolyte in the solid electrolyte layer 50 ) may be 2 ㎛ to 5 ㎛, or 2.5 ㎛ to 4 ㎛. When the average particle diameter of the sulfide-based solid electrolyte in each layer is designed in this way, the ion conduction performance of the all-solid-state secondary battery can be further improved while increasing the density of the positive electrode. Here, the average particle diameter (D 50 ) is a particle size distribution obtained by measuring the size (diameter or length of major axis) of about 20 particles in a scanning electron microscope image, for example, and the size of the particle with a cumulative volume of 50% (D 50 ) may have been calculated.

[0063] bookbinder

[0064] The binder helps the positive electrode active material particles adhere well to each other and also helps the positive electrode active material adhere well to the current collector. Representative examples of binders include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0065] Challenge

[0066] Conductive materials are used to impart conductivity to electrodes, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of conductive materials include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0067] The content of the binder and the conductive agent may be 0.5 wt% to 5 wt%, respectively, with respect to 100 wt% of the positive electrode active material layer.

[0068] The cathode active material layer may optionally further include a solid electrolyte. The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof, and specific descriptions thereof will be provided later in the section on the solid electrolyte layer.

[0069] For 100 wt% of the positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%.

[0070] In the positive electrode active material layer, the positive electrode active material may be comprised in an amount of 65 to 99 wt% and the solid electrolyte in an amount of 1 to 35 wt%, based on 100 wt% of the total of the positive electrode active material and the solid electrolyte, for example, the positive electrode active material may be comprised in an amount of 80 to 90 wt% and the solid electrolyte in an amount of 10 to 20 wt%. When the solid electrolyte is comprised in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state secondary battery can be improved without reducing the capacity.

[0071] solid electrolyte layer

[0072] The solid electrolyte layer comprises a solid electrolyte. The solid electrolyte may be a type of inorganic solid electrolyte, and may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a combination thereof. According to one embodiment, the solid electrolyte layer may comprise a sulfide-based solid electrolyte.

[0073] Sulfide-based solid electrolyte

[0074] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5--LiX (where X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z. m S n(m, n are integers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or a combination thereof.

[0075] A sulfide-based solid electrolyte can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or 50:50 to 80:20, and optionally heat-treating them. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. The ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0076] Methods for mixing sulfur-containing raw materials for producing sulfide-based solid electrolytes include mechanical milling or the solution method. Mechanical milling involves placing raw materials in a ball mill reactor and vigorously stirring them to finely atomize and mix them. Using the solution method, the raw materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can solidify the crystals of the solid electrolyte and improve ionic conductivity. For example, a sulfide-based solid electrolyte can be produced by mixing sulfur-containing raw materials and heat-treating them twice or more, resulting in a sulfide-based solid electrolyte with high ionic conductivity and robustness.

[0077] According to one embodiment, sulfide-based solid electrolyte particles can be manufactured through, for example, a first heat treatment in which sulfur-containing raw materials are mixed and calcined at 120°C to 350°C, and a second heat treatment in which the first heat treatment result is mixed and calcined at 350°C to 800°C. The first heat treatment and the second heat treatment can each be performed in an inert gas or nitrogen atmosphere. The first heat treatment can be performed for 1 to 10 hours, and the second heat treatment can be performed for 5 to 20 hours. The first heat treatment can have the effect of milling small raw materials, and the second heat treatment can synthesize the final solid electrolyte. Through two or more such heat treatments, a high-performance sulfide-based solid electrolyte with high ionic conductivity and robustness can be obtained, and such a solid electrolyte can be said to be suitable for mass production. The temperature of the first heat treatment may be, for example, 150°C to 330°C, or 200°C to 300°C, and the temperature of the second heat treatment may be, for example, 380°C to 700°C, or 400°C to 600°C.

[0078] For example, the sulfide-based solid electrolyte particles may include argyrodite-type sulfides. The argyrodite-type sulfide-based solid electrolyte particles may have an ionic conductivity of 10, which is the ionic conductivity of a typical liquid electrolyte at room temperature. -4 10 inland -2 It has a high ionic conductivity approaching the S / cm range, can form a close bond between a positive electrode active material and a solid electrolyte without causing a decrease in ionic conductivity, and can further form a close interface between an electrode layer and a solid electrolyte layer. An all-solid-state secondary battery including the same can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0079] The argyrodite-type sulfide-based solid electrolyte particles may include, for example, a compound represented by the chemical formula 21 below.

[0080] [Chemical Formula 21]

[0081] (Li a M 1 b M 2 c )(P d M 3 e )(S f M 4 g )X h

[0082] In the above chemical formula 21, 4≤a≤8, and M 1 is Mg, Cu, Ag, or a combination thereof, and 0≤b<0.5, and M 2 is Na, K, or a combination thereof, 0≤c<0.5, and M 3 is Sn, Zn, Si, Sb, Ge, or a combination thereof, and 0 <d<4, 0≤e<1 이고, M 4 is O, SO n , or a combination thereof, and 1.5≤n≤5, 3≤f≤12, 0≤g<2, and X is F, Cl, Br, I, or a combination thereof, and 0≤h≤2.

[0083] For example, in chemical formula 21, a halide element (X) may be included as an essential element, in which case 0 <h≤2로 표시될 수 있다. 일 예로 화학식 21에 M 1 Elements may be required, in which case 0 <b<0.5로 표시될 수 있다. 화학식 21에서 M 3 can be understood as an element substituted in place of P and 0 <e<1일 수 있다. 화학식 21에서 M 4 is substituted in the S position, for example, 0 <g<2일 수 있으며 S의 비율인 f는 예를 들어 3≤f≤7일 수 있다. M 4 Go SO n If SO n It can be, for example, S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, or SO5, and can be, for example, SO4.

[0084] For example, in chemical formula 21, a+b+c+h=7, d+e=1, and f+g+h=6.

[0085] As a specific example, argyrodite-type sulfide-based solid electrolyte particles include Li3PS4 and Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or combinations thereof, but are not limited thereto.

[0086] An argyrodite-type sulfide-based solid electrolyte can be manufactured by mixing raw materials such as lithium sulfide, phosphorus sulfide, and optionally lithium halide. After mixing these, a heat treatment may be performed. The heat treatment may be performed at a temperature in the range of 400°C to 600°C, for example, 450°C to 500°C, or 460°C to 490°C, and for 5 to 30 hours, 10 to 24 hours, or 15 to 20 hours. When heat treating under the above conditions, ionic conductivity can be maximized. The heat treatment may include, for example, two or more heat treatment steps. Here, manufacturing an argyrodite-type sulfide-based solid electrolyte may include, for example, a first heat treatment of mixing raw materials and calcining at 120°C to 350°C, and a second heat treatment of mixing the first heat treatment resultant again and calcining at 350°C to 800°C.

[0087] Average particle diameter (D) of sulfide-based solid electrolyte particles 50 ) may be, for example, 0.1 ㎛ to 5.0 ㎛ or 0.1 ㎛ to 3.0 ㎛, may be small particles of 0.1 ㎛ to 1.9 ㎛, or may be large particles of 2.0 ㎛ to 5.0 ㎛. The sulfide-based solid electrolyte particles may be a mixture of small particles having an average particle diameter of 0.1 ㎛ to 1.9 ㎛ and large particles having an average particle diameter of 2.0 ㎛ to 5.0 ㎛. The average particle diameter of the sulfide-based solid electrolyte particles may be measured by an electron microscope image, and for example, a particle size distribution is obtained by measuring the size (diameter or major axis length) of about 20 particles in a scanning electron microscope image, where D 50 It may have been calculated.

[0088] Oxide-based solid electrolyte

[0089] Oxide-based solid electrolytes include, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Alx Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or mixtures thereof.

[0090] Halide-based solid electrolyte

[0091] The solid electrolyte layer may further include, for example, a halide-based solid electrolyte. The halide-based solid electrolyte contains a halogen element as a main component, and may mean that the ratio of the halide element to all elements constituting the solid electrolyte is 50 mol% or more, 70 mol% or more, 90 mol% or more, or 100 mol%. For example, the halide-based solid electrolyte may not contain a sulfur element.

[0092] The halide-based solid electrolyte may contain lithium element, a metal element other than lithium, and a halogen element. The metal element other than lithium may be Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof. The halogen element may be F, Cl, Br, I, or a combination thereof, and may be Cl, Br, or a combination thereof. The halide-based solid electrolyte may contain, for example, Li a M1X6 (M is Al, As, B, Bi, Ca, Cd, Co, Cr, Fe, Ga, Hf, In, Mg, Mn, Ni, Sb, Sc, Sn, Ta, Ti, Y, Zn, Zr, or a combination thereof, X is F, Cl, Br, I, or a combination thereof, and 2≤a≤3) can be represented. The halide-based solid electrolyte may be, for example, Li2ZrCl6, Li 2.7 Y 0.7 Zr 0.3 Cl6, Li 2.5 Y 0.5 Zr 0.5 Cl6, Li 2.5 In 0.5 Zr 0.5 Cl6, Li2In 0.5 Zr 0.5 Cl6, Li3YBr6, Li3YCl6, Li3YBr2Cl4, Li3YbCl6, Li 2.6 Hf 0.4 Yb 0.6Cl6, or combinations thereof, but is not limited thereto.

[0093] bookbinder

[0094] The solid electrolyte layer may further include a binder. Binders include, for example, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluoroelastomer, natural rubber, polydimethylsiloxane, polyethylene oxide, polyvinylpyrrolidone, polyvinylpyridine, chlorosulfonated polyethylene, polyvinyl alcohol, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, polyamideimide, polyimide, poly(meth)acrylate, polyacrylonitrile, polystyrene, polyurethane, and the like. copolymers, or combinations thereof.

[0095] The binder may be included in an amount of 0.1 wt% to 3 wt% based on 100 wt% of the solid electrolyte layer, for example, 0.5 wt% to 2 wt%, or 0.5 wt% to 1.5 wt%. When the binder is included in the above range, the components within the solid electrolyte layer can be well combined without lowering the ionic conductivity of the solid electrolyte, thereby improving the durability and reliability of the battery.

[0096] Other ingredients

[0097] The solid electrolyte layer may optionally further comprise an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0098] 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.

[0099] The lithium salt may be applied without limitation on type, and may include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiSCN, LiN(CN)2, lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, or a combination thereof.

[0100] For example, the lithium salt may be an imide-based lithium salt such as LiTFSI, LiFSI, LiBETI, or a combination thereof. The imide-based lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0101] Ionic liquids are salts or molten salts that are composed only of ions and are liquid at room temperature, with a melting point below room temperature.

[0102] The ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, trizolium, and mixtures thereof, and b) BF4. - , PF6 - , AsF6 - , SbF6- , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - It may be a compound containing one or more anions selected from among.

[0103] 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.

[0104] In the solid electrolyte layer, the weight ratio of the solid electrolyte to the ionic liquid may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0105] cathode

[0106] The negative electrode may include a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive material.

[0107] In a bi-cell type battery structure according to one embodiment, as shown in FIG. 1, the negative electrode active material layer may be in contact with the solid electrolyte layer, and the negative electrode may be a single-sided negative electrode in which the negative electrode active material layer is formed only on one side of the negative electrode current collector.

[0108] The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0109] 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.

[0110] As the above lithium metal alloy, an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0111] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material is silicon, a silicon-carbon composite, SiOx(0 <x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소(Si를 제외함), 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합에서 선택됨), 또는 이들의 조합일 수 있다. 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn계 합금 또는 이들의 조합일 수 있다.

[0112] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0113] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0114] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in a mixture with a carbon-based negative electrode active material.

[0115] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% based on the total weight of the negative active material layer. For example, the negative active material layer may include 90 wt% to 99 wt% of the negative active material, 0.5 wt% to 5 wt% of the binder, and 0 wt% to 5 wt% of the conductive material.

[0116] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0117] Examples of the non-aqueous binder include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0118] The above-mentioned aqueous binder may be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluoroelastomer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0119] When using an aqueous binder as the above-mentioned negative electrode binder, a cellulose-based compound capable of imparting viscosity may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li.

[0120] The above dry binder is a polymeric material capable of being fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0121] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0122] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0123] precipitation cathode

[0124] As another example, in a battery structure according to one embodiment, the negative electrode may be a precipitation-type negative electrode. A 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.

[0125] Fig. 2 is a cross-sectional view of a bi-cell type battery structure including a precipitated negative electrode. Referring to Fig. 2, the precipitated negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) positioned on the current collector. An all-solid-state secondary battery including such a precipitated negative electrode (400') starts initial charging in a state in which no negative electrode active material is present, and during charging, a high-density lithium metal is precipitated or deposited between the current collector (401) and the negative electrode coating layer (405) or on the negative electrode coating layer (405) to form a lithium metal layer (404), which may function as a negative electrode active material. Accordingly, in an all-solid-state secondary battery that has been charged more than once, a precipitation-type negative electrode (400') may include, for example, a current collector (401), a lithium metal layer (404) positioned on the current collector, and a negative electrode coating layer (405) positioned on the lithium metal layer. The lithium metal layer (404) refers to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may be referred to as a metal layer, a lithium layer, a lithium deposition layer, or a negative electrode active material layer.

[0126] The cathode coating layer (405) may be referred to as a lithium electrodeposition induction layer or a cathode catalyst layer, and may include a lithium-philic metal, a carbon material, or a combination thereof.

[0127] The lithium-loving metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one of these or of an alloy of several types. When the metal is present in particle form, its average particle diameter (D 50 ) may be less than about 4 μm, for example, 10 nm to 4 μm.

[0128] 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.

[0129] When the cathode coating layer (405) includes both a lithium-philic metal and a carbon material, the mixing ratio of the lithium-philic 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.

[0130] The cathode coating layer (405) may include, for example, the lithium-philic metal and amorphous carbon, in which case the precipitation of lithium metal can be effectively promoted.

[0131] In one embodiment, the negative electrode coating layer (405) may include a compound in which a lithium-philic metal is supported on a carbon material. The supported compound is distinguished from a simple mixture of a lithium-philic metal and a carbon material. When the negative electrode coating layer includes a supported compound, the lithium metal layer (404) can be formed more uniformly, and the reversibility of lithium precipitation and dissociation can be improved, thereby improving the life characteristics of the all-solid-state secondary battery.

[0132] In one embodiment, the carbon material and the lithium-philic metal may be chemically bonded via sulfur. That is, the carbon material and the lithium-philic metal may not be simply physically mixed, but may be chemically bonded to each other. In this case, the bonding strength between the carbon material and the lithium-philic metal is excellent, and the problem of the carbon material and the lithium-philic metal separating from each other during the mixing process can be effectively prevented. In addition, the phenomenon of the lithium-philic metal agglomerating is prevented, so that it can be uniformly dispersed within the negative electrode coating layer, thereby uniformly distributing the current within the negative electrode and inducing uniform deposition of the lithium metal.

[0133] When carbon materials and a lithiophilic metal are chemically bonded via sulfur, peaks related to the bonding of the lithiophilic metal and sulfur can be identified in the X-ray photoelectron spectroscopy (XPS) spectrum. For example, when the lithiophilic metal contains Ag, a peak can be identified in the S2p spectrum obtained by XPS analysis in the range of 160 eV to 162 eV, which is the Ag-S bond energy.

[0134] The cathode coating layer (405) may further include a binder, which may be, for example, a conductive binder. In addition, the cathode coating layer (405) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0135] The thickness of the cathode coating layer (405) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0136] The precipitation-type negative electrode (400') may further include, for example, a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one type thereof or may be composed of multiple types of alloys. The thin film may further planarize the precipitation pattern of the lithium metal layer (404) and further improve the characteristics of the all-solid-state secondary battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0137] The lithium metal layer (404) may include lithium metal or a lithium alloy. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy.

[0138] The thickness of the lithium metal layer (404) may be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer (404) is too thin, it may be difficult to perform the role of a lithium storage, and if it is too thick, the battery volume may increase and performance may deteriorate.

[0139] When such a precipitation-type cathode is applied, the cathode coating layer (405) can play a role in protecting the lithium metal layer (404) and suppressing the precipitation growth of lithium deadlight. Accordingly, short-circuiting and capacity reduction of the all-solid-state battery can be suppressed, and the life characteristics can be improved.

[0140] All-solid-state secondary battery

[0141] In one embodiment, an all-solid-state secondary battery is provided in which two or more of the above-described battery structures are stacked. The number of stacked battery structures is not particularly limited, and may be, for example, 2 to 100, 3 to 80, or 5 to 50. In all-solid-state secondary batteries, elastic sheets are generally interposed between or at the outermost surface of the battery structures, but when a battery structure according to one embodiment is used, the elastic sheets can be omitted. However, in one embodiment, it is also possible to interpose elastic sheets as needed. That is, the all-solid-state secondary battery according to one embodiment may further include elastic sheets between and / or at the outermost surface of the above-described battery structures.

[0142] The elastic sheet basically includes a polymer resin containing a urethane resin, an acrylic resin, a silicone resin, a fluorine resin, a polyolefin resin, a styrene resin, a vinyl acetate resin, a rubber resin, a copolymer thereof, or a mixture thereof, and may optionally further include elastic particles, inorganic particles, hollow particles, a flame retardant, an initiator crosslinking agent, a coupling agent, a foaming agent, etc.

[0143] The thickness of the elastic sheet can be approximately 100 μm to 5 mm, for example 100 μm to 4000 μm, 100 μm to 3000 μm, 100 μm to 2000 μm, 100 μm to 1500 μm, 100 μm to 1000 μm, or 100 μm to 800 μm.

[0144] The elastic sheet may be in the form of a relatively soft, low-modulus pad, or in the form of a relatively hard foam, or in the form of various injection-molded products.

[0145] The shape of the 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 all-solid-state secondary battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields that require a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0146] The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0147] Example

[0148] A resin-metal composite cathode current collector was prepared in which aluminum was deposited on both sides of a polyethylene terephthalate resin sheet having a thickness of approximately 10 ㎛ to form an aluminum metal film having a thickness of approximately 200 nm.

[0149] LiNi coated with Li2O-ZrO2 0.8 Co 0.15 Mn 0.05 A cathode composition was prepared by mixing 85 wt% of an O2 cathode active material, 13.5 wt% of a lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of a polyvinylidene fluoride binder, and 0.5 wt% of a carbon nanotube conductive material. The cathode composition was coated on both sides of a prepared cathode current collector, and dried and rolled to form a cathode active material layer.

[0150] An argyrodite-type solid electrolyte Li6PS5Cl(D) was added to a binder solution in which an acrylic binder (SX-A334, Zeon) was dissolved in an isobutyryl isobutyrate (IBIB) solvent. 50=3㎛) was added and stirred to prepare a solid electrolyte slurry. The slurry contains 98.5 wt% of solid electrolyte and 1.5 wt% of binder. The prepared solid electrolyte slurry was coated on the positive electrode active material layer and dried to form a solid electrolyte layer.

[0151] Primary entry (D 50 ) carbon black with an average particle diameter (D) of about 30 nm 50 ) was prepared by mixing silver (Ag) having a diameter of approximately 60 nm in a weight ratio of 3:1, and 0.25 g of the above complex was added to 2 g of an NMP solution containing 7 wt% of polyvinylidene fluoride binder and mixed to prepare a negative electrode coating layer composition. This was applied to a nickel foil current collector using a bar coater and vacuum-dried to prepare a deposition-type negative electrode in which a negative electrode coating layer was formed on the current collector.

[0152] A bi-cell type battery structure was fabricated by laminating a cathode on a solid electrolyte layer such that the cathode coating layer is in contact with the solid electrolyte layer. This was placed in an aluminum pouch laminate film and subjected to warm isostatic pressing (WIP) at 80°C and 500 MPa for 30 minutes to fabricate the final battery structure. Five of the fabricated battery structures were laminated to fabricate an all-solid-state secondary battery.

[0153] 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.

[0154] Description of the symbol

[0155] 100: Battery structure

[0156] 200: Anode 201: Resin sheet

[0157] 202: Metal film 203: Positive electrode active material layer

[0158] 300: Solid electrolyte layer

[0159] 400: Cathode 401: Cathode current collector

[0160] 403: Negative active material layer

[0161] 400': Precipitation type cathode 404: Lithium metal layer

[0162] 405: Cathode coating layer

Claims

1. Bipolar collector, A layer of positive electrode active material located on both sides of the positive electrode collector, A solid electrolyte layer positioned on the positive electrode active material layer, and A battery structure having a bi-cell structure including a cathode positioned on the solid electrolyte layer, A battery structure in which the positive electrode collector includes a resin sheet and a metal film positioned on both sides of the resin sheet.

2. In paragraph 1, The thickness of the resin sheet of the above positive electrode collector is 1 ㎛ to 100 ㎛, A battery structure wherein the thickness of the metal film of the positive electrode collector is 10 nm to 2 ㎛.

3. In paragraph 2, The thickness of the resin sheet of the above positive electrode collector is 5 ㎛ to 30 ㎛, A battery structure wherein the thickness of the metal film of the positive electrode collector is 10 nm to 900 nm.

4. In paragraph 1, A battery structure wherein the thickness of the positive electrode current collector is 1.02 ㎛ to 104 ㎛.

5. In paragraph 1, A battery structure including the resin sheet of the above cathode current collector is selected from the group consisting of polyethylene, polypropylene, polyamide, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyacrylonitrile, poly(meth)acrylate, polymethyl(meth)acrylate, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl chloride, polyurethane, epoxy resin, nylon resin, acrylic resin, polystyrene, polyethylene oxide, polyvinyl alcohol, silicone resin, styrene-butadiene rubber, acrylonitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, copolymers thereof, or mixtures thereof.

6. In paragraph 1, A battery structure in which the metal film of the above cathode current collector includes Al, Cu, Fe, Ni, SUS, Ti, or a combination thereof.

7. In paragraph 1, The above positive electrode active material layer includes a positive electrode active material containing a lithium transition metal composite oxide, and a sulfide-based solid electrolyte, The above solid electrolyte layer is a battery structure including a sulfide-based solid electrolyte.

8. In paragraph 7, A battery structure in which the sulfide-based solid electrolyte in the positive electrode active material layer and the sulfide-based solid electrolyte in the solid electrolyte layer each include argyrodite-type sulfide.

9. In paragraph 7, The average particle size (D) of the sulfide-based solid electrolyte in the above cathode active material layer 50 ) is the average particle diameter (D) of the sulfide-based solid electrolyte in the solid electrolyte layer. 50 ) is a battery structure smaller than the battery.

10. In Article 9, The average particle size (D) of the sulfide-based solid electrolyte in the above cathode active material layer 50 ) is 0.1 ㎛ to 1.9 ㎛, The average particle size (D) of the sulfide-based solid electrolyte in the above solid electrolyte layer 50 ) is a battery structure having a size of 2 ㎛ to 5 ㎛.

11. In paragraph 1, The above negative electrode is a battery structure including a negative electrode current collector, and a negative electrode coating layer positioned on the negative electrode current collector and containing a lithium-philic metal, a carbon material, or a combination thereof.

12. In Article 11, In the above cathode coating layer, the lithium-philic metal includes Al, Ag, Au, Bi, Cu, Ge, In, Mg, Ni, Pd, Pt, Si, Sn, Zn, or a combination thereof, The above carbon material is an amorphous carbon material, which is a battery structure.

13. In Article 11, A battery structure further comprising a lithium metal layer formed by charging between the negative electrode current collector and the negative electrode coating layer.

14. An all-solid-state secondary battery having two or more battery structures according to any one of claims 1 to 13 laminated.

15. In paragraph 14, An all-solid-state secondary battery further comprising an elastic sheet positioned between the battery structures and / or at the outermost portion of the battery structures.

16. In Article 15, An all-solid-state secondary battery wherein the thickness of the elastic sheet is 100 ㎛ to 5 mm.

Images