All-solid-state secondary battery and manufacturing method thereof

Abstract

The present invention provides an all-solid-state secondary battery and a manufacturing method thereof, the all-solid-state secondary battery having at least one structure including a unit cell and a frame surrounding the outer surface of the unit cell, wherein the unit cell includes at least one positive electrode current collector layer, at least one positive electrode mixture layer, at least one solid electrolyte layer, at least one negative electrode mixture layer, and at least one negative electrode current collector layer, and the positive electrode mixture layer, the solid electrolyte layer, the negative electrode mixture layer are stacked in the height direction, have the same area, and satisfy Condition 1: [Condition 1] (thickness of unit cell (excluding thickness of current collector layer) / 2) x 70% ≤ thickness of frame in direction perpendicular to height direction ≤ (thickness of unit cell (excluding thickness of current collector layer) / 2) x 130%. According to the present invention, cracks in the solid electrolyte layer and short-circuiting of the battery are controlled, thereby providing an all-solid-state secondary battery having excellent capacity and lifetime characteristics, and a manufacturing method thereof.

Description

All-solid-state secondary battery and method for manufacturing the same

[0001] The present invention relates to an all-solid-state secondary battery and a method for manufacturing the same. The present application claims the benefit of priority based on Korean Patent Application No. 2024-0155053 filed on November 5, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of the specification.

[0002] All-solid-state secondary batteries require high heat and pressure to lower resistance and improve contact between solid particles. However, applying high heat and pressure causes the solid electrolyte layer to become brittle; this leads to cracking in the electrolyte layer and a tendency for battery short circuits due to volume changes (expansion or contraction) during charging and discharging. In particular, the surface area of ​​the positive electrode composite layer is generally designed to be smaller than that of the solid electrolyte layer and the negative electrode composite layer; applying high heat and pressure to such a structure exacerbates the problems of cracking and battery short circuits.

[0003] The present invention aims to solve the above problems by controlling cracks in the solid electrolyte layer and short circuits in the battery, and to provide an all-solid-state secondary battery having excellent capacity and lifespan characteristics and a method for manufacturing the same.

[0004] One aspect of the present invention may relate to an all-solid-state secondary battery comprising at least one structure including a unit cell and a frame surrounding the outer surface of the unit cell, wherein the unit cell comprises at least one positive current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, and a negative current collector layer, and wherein the positive composite layer, the solid electrolyte layer, and the negative composite layer are stacked in the height direction, have equal areas, and satisfy the following condition 1:

[0005] [Condition 1]

[0006] (Unit cell thickness (excluding current collector layer thickness) / 2)×70% ≤ Thickness in the direction perpendicular to the height direction of the frame ≤ (Unit cell thickness (excluding current collector layer thickness) / 2)×130%.

[0007] In one embodiment, the unit cell may be characterized by sequentially including an anode current collector layer, an anode composite layer, a solid electrolyte layer, a cathode composite layer, and a cathode current collector layer along the height direction.

[0008] In one embodiment, the unit cell may be characterized by comprising, along the height direction, an anode current collector layer, a pair of anode composite layers disposed between the anode current collector layers, a pair of solid electrolyte layers disposed between the pair of anode composite layers, a pair of cathode composite layers disposed between the pair of solid electrolyte layers, and a pair of cathode current collector layers disposed between the pair of cathode composite layers.

[0009] In one embodiment, the unit cell may be characterized by comprising, along the height direction, a negative current collector layer, a pair of negative composite layers disposed between the negative current collector layers, a pair of solid electrolyte layers disposed between the pair of negative composite layers, a pair of positive composite layers disposed between the pair of solid electrolyte layers, and a pair of positive current collector layers disposed between the pair of positive composite layers.

[0010] In one embodiment, the all-solid-state secondary battery of the present invention may be characterized by including a buffer pad on at least one surface of the structure.

[0011] In one embodiment, the cushioning pad may be characterized by having an elastic modulus of 0.1 to 5 GPa.

[0012] In one embodiment, the thickness of the cushioning pad may be characterized as being 80% to 150% of the thickness in the direction perpendicular to the height direction of the frame.

[0013] In one embodiment, the thickness of the buffer pad may be 10 to 500 μm.

[0014] In one embodiment, the all-solid-state secondary battery of the present invention may be characterized by including a plurality of structures stacked in the height direction and each of the adjacent structures including a buffer pad.

[0015] In one embodiment, the all-solid-state secondary battery of the present invention may be characterized by further including a buffer pad on each of the outermost surfaces of a plurality of structures.

[0016] In one embodiment, the area of ​​the cushioning pad may be characterized as being equal to the area of ​​the structure.

[0017] In one embodiment, the frame may be characterized as being a flame-retardant inert member comprising a matrix and a filler; or an insulating layer comprising a polymer, or a composite of a polymer and an inorganic material.

[0018] In one embodiment, the cushioning pad may be characterized by including an elastic material.

[0019] In one embodiment, the elastic material may be characterized by comprising polyurethane, polyacrylate, fluorinated polymer, natural rubber, spandex, butyl rubber, fluoroelastomer, elastomer, ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone rubber, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), neoprene, acrylic, copolymers thereof, or combinations thereof.

[0020] In one embodiment, the solid electrolyte layer may be characterized by comprising a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte.

[0021] In another aspect, the present invention may relate to a method for manufacturing an all-solid-state secondary battery having at least one structure comprising a unit cell and a frame surrounding the outer surface of the unit cell, comprising the step (Step S1) of manufacturing a structure having a unit cell comprising at least one positive current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, and a negative current collector layer, and a frame surrounding the outer surface of the unit cell; and the step (Step S2) of applying isotropic pressure to the structure, wherein the positive composite layer, the solid electrolyte layer, and the negative composite layer are stacked in the height direction, have equal areas, and satisfy the following condition 1:

[0022] [Condition 1]

[0023] (Unit cell thickness (excluding current collector layer thickness) / 2)×70% ≤ Thickness in the direction perpendicular to the height direction of the frame ≤ (Unit cell thickness (excluding current collector layer thickness) / 2)×130%.

[0024] In one embodiment, the method for manufacturing an all-solid-state secondary battery of the present invention may further include the step (step S3) of introducing a buffer pad on at least one surface of the structure.

[0025] According to the present invention, cracks in the solid electrolyte layer and short circuits in the battery are controlled, thereby providing an all-solid-state secondary battery having excellent capacity and lifespan characteristics and a method for manufacturing the same.

[0026] FIGS. 1 to 6 are images of a cross-section of an all-solid-state secondary battery (case not shown) according to one embodiment of the present invention, viewed from the side.

[0027] FIG. 7 is an image showing a cross-section of an all-solid-state secondary battery (case not shown) according to one embodiment of the present invention, viewed from the top or bottom.

[0028] FIG. 8 illustrates a flowchart of a method for manufacturing an all-solid-state secondary battery according to one embodiment of the present invention.

[0029] FIG. 9 is a graph showing the results of evaluating capacity and Coulomb efficiency according to cycles for an all-solid-state secondary battery according to one embodiment of the present invention.

[0030] Terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor may appropriately define the concept of the terms to best describe his invention. Accordingly, the configurations of the embodiments described in this specification are merely one preferred embodiment of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application. In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0031] In this specification, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Thus, for example, a composition comprising compound A may include compounds other than A. However, the term “comprising” also encompasses, in a more restrictive sense as a specific embodiment thereof, “essentially / essentially composed of” and “composed of,” so, for example, a “composition comprising compound A” may also be (essentially / essentially) composed of compound A.

[0032] In connection with this, terms such as “comprising” or “having,” as described in this specification, are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0033] In the present specification, when any member, layer, film, etc. is described as being located “on” another arbitrary member, layer, film, etc., this includes not only cases where such member, layer, film, etc. is in contact with another member, layer, film, etc., but also cases where another member, layer, film, etc. exists between two members, layers, films, etc.

[0034] In this specification, “identical” area, length, width, thickness, and / or shape includes all cases having “substantially identical” area, length, width, thickness, and / or shape, except where the area, length, width, thickness, and / or shape are intentionally made different from one another. “Identical” area, length, width, and / or thickness includes a range in which the unintended difference in the area, length, width, and / or thickness of the objects being compared is, for example, less than 1%, less than 0.5%, or less than 0.1%.

[0035] The drawings attached to this specification illustrate an embodiment of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the content of the invention; therefore, the present invention should not be interpreted as being limited only to the matters described in the drawings.

[0036] In the drawings, thicknesses have been enlarged or reduced to clearly represent various layers and regions. Throughout the specification, similar parts are given the same reference numerals. In this specification and drawings, components having substantially the same functional configuration are referred to by the same reference numerals, and redundant descriptions are omitted.

[0037] The first aspect of the present invention relates to an all-solid-state secondary battery. The all-solid-state secondary battery of the present invention will be described below using FIGS. 1 to 7, but is not limited thereto.

[0038] The all-solid-state secondary battery of the present invention is an all-solid-state secondary battery having at least one structure (1), for example, a unit cell (10) and a frame (20) covering the outer surface of the unit cell (10), wherein the unit cell (10) may each include at least one positive current collector layer (101), a positive composite layer (102), a solid electrolyte layer (103), a negative composite layer (104), and a negative current collector layer (105), and the positive composite layer (102), the solid electrolyte layer (103), and the negative composite layer (104) may be stacked in the height direction and may have the same area as each other and satisfy the following condition 1:

[0039] [Condition 1]

[0040] (Unit cell thickness (excluding current collector layer thickness) / 2)×70% ≤ Thickness in the direction perpendicular to the height direction of the frame ≤ (Unit cell thickness (excluding current collector layer thickness) / 2)×130%.

[0041] In this specification, the 'height direction' may be, for example, the same direction as the Y-axis direction of FIGS. 1 to 6, and may also be, for example, the same direction as the thickness direction of each layer.

[0042] In this specification, the frame (20) may have a square structure that surrounds the outer surface of the unit cell (10), for example, as shown in FIG. 7. At this time, although not shown in FIG. 7, a portion of the current collector layer (101 or 105) may be located in the frame (20) area, and the frame (20) may be positioned so as not to overlap with the portion of the current collector layer or tab. In this case, for example, the cross-section of the current collector layer (101 or 105) cut in the X-axis direction (horizontal direction) in FIG. 1 to 6 may have a square structure with a portion cut off. However, even in this case, the cross-section of the positive electrode composite layer (102), solid electrolyte layer (103), or negative electrode composite layer (104) cut in the X-axis direction may have a square structure. Alternatively, in another example, the frame (20) may have a square structure that surrounds the outer surface of the unit cell (10), but may be arranged to surround only the outer surface of the positive composite layer, solid electrolyte layer, and negative composite layer, excluding the current collector layer. In some cases, multiple frames (20) may be introduced per unit cell (10). The positive tab and negative tab, or the positive non-positive part and the negative non-positive part, may each protrude in the same direction as, for example, as shown in FIGS. 1 to 6, or in other examples, may protrude in different directions (for example, if the positive tab (or positive non-positive part) protrudes in the X-axis direction, the negative tab (or negative non-positive part) protrudes in the Y-axis direction).

[0043] The present invention can provide an all-solid-state secondary battery having excellent capacity and lifespan characteristics by including a frame that completely surrounds the outer surface of a unit cell, even though the areas of the positive electrode composite layer, the solid electrolyte layer, and the negative electrode composite layer are the same, while satisfying the above conditions, and preventing the occurrence of dendrites on the outer surface of the unit cell and controlling short circuits.

[0044] In the above condition 1, “unit cell thickness (except for the thickness of the current collector layer) (e.g., T in FIG. 1 or T1+T2 in FIG. 2 and FIG. 3)” may mean the sum of the thicknesses of each of the positive composite layer (102), solid electrolyte layer (103), and negative composite layer (104) included in the unit cell (10).

[0045] In the above condition 1, the “thickness (TF) in the direction perpendicular to the height direction of the frame” may refer to the thickness of each frame (20) region protruding from the unit cell (10) in the first direction and the second direction, respectively, when viewing the all-solid-state secondary battery from the top or bottom, as shown in FIG. 7. However, FIG. 7 does not show the protrusion of the negative electrode current collector (negative electrode non-part or negative electrode tab) or the protrusion of the positive electrode current collector (positive electrode non-part or positive electrode tab), and in some cases, the protrusion of the negative electrode current collector or the protrusion of the positive electrode current collector may penetrate a part of the frame. In this case, the “thickness (TF) in the direction perpendicular to the height direction of the frame” may be measured for the region where the protrusion does not exist.

[0046] In this specification, “unit cell thickness,” “unit cell area,” “thickness in a direction perpendicular to the height direction of the frame,” “frame height,” “frame area,” “area of ​​the structure,” “thickness of the cushioning pad,” or “area of ​​the cushioning pad,” etc., may refer to values ​​in a state where no pressure is applied, values ​​after an isotropic pressurization step, or values ​​in the final finished product as described below.

[0047] In particular, the present invention has confirmed that when the areas of the positive electrode composite layer, the solid electrolyte layer, and the negative electrode composite layer are equal to each other, cracking of the solid electrolyte layer and short circuits in the battery are controlled by controlling the thickness (TF) in a direction perpendicular to the height direction of the frame to satisfy Condition 1, thereby enabling the provision of an all-solid-state secondary battery having excellent capacity and lifespan characteristics. Although no specific reason has been revealed, it is expected that controlling the thickness (TF) in a direction perpendicular to the height direction of the frame as in Condition 1 prevents dendrite growth from occurring at the negative electrode edge (e.g., between the negative electrode composite layer and the negative electrode current collector layer) or the positive electrode (e.g., the positive electrode composite layer or the positive electrode current collector layer) from being pushed toward the frame, thus allowing for the control of short circuits or active material loss. Furthermore, in the case of stacking multiple unit cells (and structures including the same), it is expected that uniform pressure can be applied to the unit cells when driving pressure is applied, as each unit cell (and structures including the same) is stacked flatly.

[0048] In order to further enhance the above effect, the “thickness (TF) in the direction perpendicular to the height direction of the frame” may be 75% or more, 80% or more, 85% or more, 90% or more, 92% or more, 94% or more, 96% or more, or 98% or more with respect to (unit cell thickness (excluding the thickness of the current collector layer) / 2), or 125% or less, 120% or less, 115% or less, 110% or less, 108% or less, 106% or less, 104% or less, or 102% or less, and most preferably 100%.

[0049] In the present invention, the “frame height (HF)” may be the same as, for example, the unit cell thickness or the unit cell thickness excluding the thickness of the current collector layer (e.g., T in FIG. 1 or T1+T2 in FIG. 2 and FIG. 3). Even within a single structure (1), for example, there may exist both an area where the “frame height (HF)” is the unit cell thickness and an area where the “frame height (HF)” is the unit cell thickness excluding the thickness of the current collector layer.

[0050] The above unit cell (10) may be, for example, a monocell or a bicell.

[0051] Specifically, for example, the unit cell (10) of the present invention may be a monocell as shown in FIG. 1. The unit cell (10) may be characterized by sequentially including, for example, a positive current collector layer (101), a positive composite layer (102), a solid electrolyte layer (103), a negative composite layer (104), and a negative current collector layer (105) along the height direction.

[0052] Additionally, specifically, for example, the unit cell (10) of the present invention may be a bicell as shown in FIG. 2 or FIG. 3. The unit cell (10) may be characterized by comprising, for example as in FIG. 2, a positive current collector layer (101), a pair of positive composite layers (102) disposed between the positive current collector layer (101), a pair of solid electrolyte layers (103) disposed between the pair of positive composite layers (102), a pair of negative composite layers (104) disposed between the pair of solid electrolyte layers (103), and a pair of negative current collector layers (105) disposed between the pair of negative composite layers (104) along the height direction. The above unit cell may also be characterized by including, for example as in FIG. 3, a negative current collector layer (105), a pair of negative composite layers (104) disposed between the negative current collector layer (105), a pair of solid electrolyte layers (103) disposed between the pair of negative composite layers (104), a pair of positive composite layers (102) disposed between the pair of solid electrolyte layers (103), and a pair of positive current collector layers (101) disposed between the pair of positive composite layers (102).

[0053] The all-solid-state secondary battery of the present invention may also be characterized by including a buffer pad (30) on at least one surface of the structure (1), for example. By controlling the characteristics of the buffer pad in conjunction with the aforementioned characteristics as follows, the all-solid-state secondary battery of the present invention can sufficiently absorb the volume change of the electrode due to charging and discharging, and accordingly, the lifespan or capacity characteristics of the battery can be further improved.

[0054] The above cushioning pad (30) may be characterized, for example, having an elastic modulus of 0.1 to 5 GPa. In other examples, the above cushioning pad (30) may have an elastic modulus of 0.2 GPa or more, 0.3 GPa or more, 0.4 GPa or more, 0.5 GPa or more, 0.6 GPa or more, 0.7 GPa or more, 0.8 GPa or more, 0.9 GPa or more, 1 GPa or more, 1.1 GPa or more, 1.2 GPa or more, 1.3 GPa or more, 1.4 GPa or more, 1.5 GPa or more, 1.6 GPa or more, 1.7 GPa or more, 1.8 GPa or more, or 1.9 GPa or more, or 4.5 GPa or less, 4 GPa or less, 3.5 GPa or less, 3 GPa or less, or 2.5 GPa or less. The above elastic modulus may be measured, for example, by a Universal Testing Machine (UTM), but is not limited thereto, and may be measured by a known method.

[0055] The thickness of the buffer pad (30) may be characterized as being, for example, 80% to 150% of the thickness (TF) in the direction perpendicular to the height direction of the frame. In another example, the thickness of the buffer pad (30) may be 85% or more, 90% or more, 95% or more, 100% or more, 105% or more, or 110% or more, or 145% or less, 140% or less, 135% or less, 130% or less, 125% or less, 120% or less, or 115% or less of the thickness (TF) in the direction perpendicular to the height direction of the frame. By controlling the thickness of the buffer pad (30) to the above ratio with respect to the thickness (TF) in the direction perpendicular to the height direction of the frame, it may be possible to provide an all-solid-state secondary battery having superior capacity characteristics and lifespan characteristics.

[0056] In this specification, thickness may be average thickness, maximum thickness and / or minimum thickness and may be measured according to known methods.

[0057] The above-mentioned cushioning pad (30) may be characterized by having a thickness of, for example, 10 to 500 μm. In other examples, the above-mentioned cushioning pad (30) may have a thickness of 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, 150 μm or more, 160 μm or more, 170 μm or more, 180 μm or more, or 190 μm or more, or 450 μm or less, 400 μm or less, 350 μm or less, 300 μm or less, or 250 μm or less.

[0058] The all-solid-state secondary battery of the present invention may include a plurality of structures (1) stacked in the height direction, for example, as shown in FIGS. 4 to 6. FIG. 4 is an example of an all-solid-state secondary battery including a plurality of monocells as unit cells (10), and FIGS. 5 and 6 are examples of an all-solid-state secondary battery including a plurality of bicells as unit cells (10).

[0059] The all-solid-state secondary battery of the present invention may be characterized by including a buffer pad (30) between each of the adjacent structures (1), for example. By doing so, it is possible to provide an all-solid-state secondary battery with improved battery life or capacity characteristics by absorbing the volume change of the battery due to charging and discharging.

[0060] The all-solid-state secondary battery of the present invention may also be characterized by further including a buffer pad (30) on each of the outermost surfaces of a plurality of structures (1), for example. Accordingly, it is possible to control volume change according to driving pressure and offset damage to the battery, thereby providing an all-solid-state secondary battery with superior lifespan or capacity characteristics.

[0061] The area of ​​the buffer pad (30) may be characterized as being equal to, for example, the area of ​​the structure (1). The area of ​​the structure (1) may, for example, mean the sum of the area of ​​the unit cell (A1) and the area of ​​the frame (A2). In this specification, the area of ​​the unit cell (A1) may be equal to the area of ​​the retaining portion of the current collector layer, the area of ​​the composite layer, and the area of ​​the solid electrolyte layer, respectively. In this specification, the area of ​​the frame (A2) may, for example, mean the area of ​​the square structure of FIG. 7 (light blue area). However, depending on the case, the area of ​​the buffer pad (30) may be adjusted, for example, the area of ​​the buffer pad (30) may be equal to or greater than the area of ​​the unit cell (A1). For example, the area of ​​the buffer pad (30) may be equal to the sum of the retaining portion and the non-retaining portion of the current collector layer.

[0062] The above frame may be characterized as, for example, a flame-retardant inert member comprising a matrix and a filler; or an insulating layer comprising a polymer, or a composite of a polymer and an inorganic material, but is not limited thereto, and known materials that can prevent cracks in the layers constituting the unit cell and / or all-solid-state secondary battery, etc., which may occur during the pressurization process, while not hindering the purpose of the present invention may be combined and used in appropriate amounts.

[0063] The above frame may be a flame-retardant inert member comprising, for example, a matrix and a filler. The matrix may comprise, for example, a substrate and a reinforcing material. The substrate may comprise, for example, a first fibrous material. The first fibrous material may comprise, for example, an insulating material, one or more selected from pulp fibers, insulating polymer fibers, and ion-conducting polymer fibers. The reinforcing material may comprise, for example, a second fibrous material. The second fibrous material may be, for example, a flame-retardant material, such as glass fibers, metal oxide fibers, ceramic fibers, etc. The filler may be disposed, for example, inside the matrix, on the surface of the matrix, or both inside and on the surface. The filler may be, for example, an inorganic material. The filler may be, for example, a moisture getter. The above filler can effectively suppress ignition of the all-solid-state secondary battery by releasing adsorbed moisture when the temperature of the all-solid-state secondary battery increases excessively due to thermal runaway caused by the charging and discharging process of the all-solid-state secondary battery or external impact. That is, the filler may be, for example, a flame retardant. The above filler may be, for example, a metal hydroxide having moisture adsorption properties, such as Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, TI(OH)3, Zr(OH)4, Al(OH)3, or a combination thereof. The above flame-retardant inert member may further include, for example, a binder. The above binder may be, for example, a curable polymer that hardens by heat and / or pressure. The above binder may be, for example, a fluorine-based binder such as polyvinylidene fluoride, or an acrylic-based binder such as polyacrylate. The flame-retardant inert member may additionally include other materials in addition to the aforementioned substrate, reinforcing material, filler, and / or binder.The flame-retardant inert member may further include one or more selected from, for example, paper, insulating polymers, ion-conducting polymers, insulating inorganic materials, oxide-based solid electrolytes, and sulfide-based solid electrolytes. The flame-retardant inert member may not include, for example, an electrode active material. The flame-retardant inert member may be a member made of a material other than the electrode active material, which is a material used in the relevant technical field.

[0064] The above frame may be an insulating layer comprising a polymer, or a composite of a polymer and an inorganic material, in other examples. The polymer may include, for example, a fluorinated polymer, a cellulose-3 polymer, an epoxy resin, or a combination thereof. Examples of the fluorinated polymer may be a homopolymer of vinylidene fluoride monomers, or a copolymer of vinylidene fluoride monomers and one or more fluorine-containing monomers selected from tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, fluorovinyl, and perfluoroalkyl vinyl ethers. Specifically, the vinylidene monomer may be a vinylidene fluoride homopolymer, a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-chlorotrifluoroethylene copolymer, etc. Examples of the above-mentioned cellulose-based polymers may include one or more selected from cellulose, methyl cellulose, ethyl cellulose, butyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate. There are no restrictions on the form of the above-mentioned cellulose-based polymer, but it may be, for example, in the form of nanofibers. The above-mentioned epoxy resin may be one or more selected from cresol novolak epoxy resin, bisphenol A type epoxy resin, bisphenol A type novolak epoxy resin, phenol novolak epoxy resin, tetrafunctional epoxy resin, biphenyl type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, urethane modified epoxy resin, and combinations thereof, but is not limited thereto. The above-mentioned inorganic material may include, for example, metal oxides, metal hydroxides, or combinations thereof. Examples of the above-mentioned inorganic material may include Al2O3, Al(OH)3, etc., but are not limited thereto, and any inorganic material usable in the field of all-solid-state secondary batteries may be used.

[0065] The above frame may have a single-layer structure or a multi-layer structure, for example. A frame having a multi-layer structure may have a two-layer structure, a three-layer structure, a four-layer structure, or a five-layer structure, for example. Each of the above layers may have a different composition.

[0066] The above frame may be used in various forms, such as, for example, film, tape, sheet, polymer resin, or gasket, but is not limited thereto and may be used in any known form used in the industry.

[0067] The above cushioning pad may include, for example, an elastic material.

[0068] The above elastic material may include, but is not limited to, polyurethane, polyacrylate, fluorinated polymer, natural rubber, spandex, butyl rubber (or halogenated butyl rubber), fluoroelastomer, elastomer, ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone rubber, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), neoprene (or chloroprene), acrylic, copolymers thereof, or combinations thereof, and may be used without limitation as long as it is an elastic material that does not impede the purpose of the present invention.

[0069] The above-mentioned cushioning pad may be in the shape of a sheet or a plate, or have a rectangular shape when viewed from a planar perspective. The thickness direction of the above-mentioned cushioning pad may coincide with the stacking direction of the unit cell.

[0070] The above cushioning pad may be, for example, a porous polymer foam, a porous polymer sponge, or rubber, but is not limited thereto. Any material having elasticity and resilience that is used in the industry, as long as it does not impede the purpose of the present invention, may be used without limitation.

[0071] The above positive current collector layer is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and may include, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or a surface treated with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel.

[0072] The above-mentioned anode composite layer may be, for example, an anode active material layer. The above-mentioned anode active material layer may include, for example, an anode active material, a conductive material, a binder, and / or a solid electrolyte, and may additionally include additives in some cases.

[0073] The above-mentioned positive electrode active material may include, for example, one or more selected from the group consisting of lithium transition metal oxides, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, and vanadium oxide. The lithium transition metal oxide may be lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide (lithium manganate), or lithium iron phosphate, or a combination thereof. The positive electrode active material is not limited thereto and may be any material used as a positive electrode active material in the relevant technical field. Each positive electrode active material may be used individually or in a mixture of two or more types.

[0074] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (wherein 0.90≤a≤1, and 0≤b≤0.5); Li a Ni 1-b-c Co b B c O 2-αF2(wherein 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0 <α<2); Li a Ni 1-b-c Mn b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0≤α≤2); Li a Ni 1-b-c Co b B c D α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a E 1-b B b O 2-c D c (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B b O 4-c D c (In the above formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a CoG b O2(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G b O4(wherein the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-cMn b B c O 2-α F2(wherein 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2(wherein 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2(wherein the above equation, 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0 ≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2(wherein 0.90≤a≤1, 0.001≤b≤0.1); QO2;QS2;LiQS2;V2O5;LiV2O5;LiIO2;LiNiVO4;Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f)Fe2(PO4)3(0≤f≤2); it may be a compound represented by any one of the chemical formulas of LiFePO4. In such a compound, A is Ni, Co, Mn, or a combination thereof; B 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; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J may be V, Cr, Mn, Co, Ni, Cu, or a combination thereof. As a positive electrode active material, a compound having a coating layer added to the surface of such a compound may be used, or a mixture of the compound described above and the compound having a coating layer added may be used. A coating layer added to the surface of such compounds may contain, for example, a lithium ion conductive oxide. The lithium ion conductive oxide is, for example, LiNbO3,Li4Ti5O 12 Examples include Li3PO4, but are not limited thereto. The compounds forming this coating layer may be amorphous or crystalline. Methods for forming the coating layer may include, for example, spray coating or immersion methods, but can be selected without limitation as long as they do not adversely affect the physical properties of the cathode active material.

[0075] When the above-mentioned cathode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), it may be possible to increase the capacity density of the all-solid-state secondary battery and reduce the metal leaching of the cathode active material in the charged state. Accordingly, the cycle characteristics of the all-solid-state secondary battery in the charged state may be improved.

[0076] The shape of the above-mentioned positive electrode active material may be a particle shape, for example, a sphere, an elliptical sphere, etc. The particle size of the positive electrode active material is not particularly limited and must be within a range applicable to the positive electrode active material of a conventional all-solid-state secondary battery. The content of the positive electrode active material is also not particularly limited and must be within a range applicable to the positive electrode of a conventional all-solid-state secondary battery.

[0077] The above conductive material is not particularly limited as long as it possesses conductivity without causing chemical changes in the battery; specifically, graphite, carbon-based materials, metal powder or metal fiber, needle-shaped or branched conductive whiskers, conductive metal oxides, conductive polymers, and any one of these or a mixture thereof may be used. More specifically, graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, or silver; needle-shaped or branched conductive whiskers such as zinc oxide whiskers, calcium carbonate whiskers, titanium dioxide whiskers, silicon oxide whiskers, silicon carbide whiskers, aluminum borate whiskers, magnesium borate whiskers, potassium titanate whiskers, silicon nitride whiskers, silicon carbide whiskers, and alumina whiskers; Examples include conductive metal oxides such as titanium oxide, or conductive polymers such as polyphenylene derivatives, and any one or more of these may be used.

[0078] The above-mentioned anode binder is any one selected from the group consisting of N,N-bis[3-(triethoxysilyl)propyl]urea, polyethylene oxide (PEO), poly(vinylidene fluoride) (PVDF), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP), or a mixture of two or more of these; N,N-bis[3-(triethoxysilyl)propyl]urea, polyethylene oxide (PEO), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP); conjugated diene rubber latex such as acrylonitrile-based styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), methyl butadiene methacrylate rubber (MBR), and butadiene rubber (BR); carboxymethylcellulose (CMC). It may be any one selected from the group consisting of starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, etc., or a mixture of two or more of these.

[0079] The solid electrolyte included in the anode composite layer may be, for example, the same or different from the solid electrolyte included in the solid electrolyte layer and / or the cathode active material layer described later. The solid electrolyte included in the anode composite layer may, for example, have a smaller average particle size compared to the solid electrolyte included in the solid electrolyte layer described later. For example, the average particle size of the solid electrolyte included in the anode composite layer may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte included in the solid electrolyte layer.

[0080] The above-mentioned anode composite layer may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids. Known materials generally used in electrodes of all-solid-state secondary batteries may be used as the fillers, coating agents, dispersants, ion conductivity aids, etc. that the anode composite layer may include.

[0081] The above solid electrolyte layer may be characterized by including, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte.

[0082] The above sulfide-based solid electrolyte is, for example, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li2S-SiS2-P2S5-LiI,Li2S-P2S5,Li2S-P2S5-LiX (X is a halogen element), Li2S-B2S3,Li2S-P2S5-Z m S n (m, n are positive numbers), Z is one of Ge, Zn, or Ga, L i2 S-GeS2,Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) and Li 7-x PS 6-x I xIt may be one or more selected from (0≤x≤2). Sulfide-based solid electrolytes can be manufactured by processing starting materials, such as Li2S or P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In the present invention, the sulfide-based solid electrolyte may, for example, include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the above-mentioned sulfide-based solid electrolyte materials.

[0083] The above sulfide-based solid electrolyte is, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0084] The density of the above-mentioned azyrodite-type solid electrolyte may be, for example, 1.5 to 2.0 g / cc. Since the above-mentioned azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte by Li can be effectively suppressed.

[0085] The elastic modulus of the above sulfide-based solid electrolyte may be, for example, 15 to 35 GPa.

[0086] The above oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, LLTO-based compounds, Li6La2CaTa2O 12 ,Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 ,Li3BO 2.5 N 0.5 ,Li9SiAlO8,LAGP-based compounds, LATP-based compounds, Li1 +x Ti 2-x Al x Si y (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where, 0≤x≤1, 0≤y≤1), LiTi x Zr 2-x It may include one or more selected from (PO4)3 (wherein, 0≤x≤1, 0≤y≤1), LISICON-based compounds, LIPON-based compounds, perovskite-based compounds, Nasicon-based compounds and LLZO-based compounds.

[0087] The above-mentioned polymer-based solid electrolyte is a composite of a lithium salt and a polymer resin, that is, a polymer electrolyte material formed by adding a polymer resin to a solvated lithium salt, approximately 1 x 10⁻⁶ -7 S / cm or more, preferably about 1x10 -5 It can exhibit ionic conductivity greater than S / cm.

[0088] Non-limiting examples of the above polymer resins include polyether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociators, etc., and may include one or more of these. In addition, the above polymer electrolyte may be a branched copolymer, comb-like polymer, and cross-linked polymer resin, etc., in which an amorphous polymer such as PMMA, polycarbonate, polysiloxane (PDMS), and / or phosphazene is copolymerized as a comonomer to a polyethylene oxide (PEO) main chain, and may include one or more of these.

[0089] The aforementioned lithium salt is an ionizable lithium salt, Li + X - It can be expressed as. The anion of such lithium salts is not particularly limited, but F - ,Cl - ,Br - ,I - ,NO3 - ,N(CN)2 - ,BF4 - ,ClO4 - ,PF6 - ,(CF3)2PF4 - ,(CF3)3PF3 - ,(CF3)4PF2 - ,(CF3)5PF - ,(CF3)6P - ,CF3SO3 - ,CF3CF2SO3 - ,(CF3SO2)2N - ,(FSO2)2N - ,CF3CF2(CF3)2CO - ,(CF3SO2)2CH - ,(SF5)3C -,(CF3SO2)3C - ,CF3(CF2)7SO3 - ,CF3CO2 - ,CH3CO2 - ,SCN - ,(CF3CF2SO2)2N - Examples of the back can be given.

[0090] The above cathode composite layer may be, for example, a cathode active material layer or a non-cathode coating layer.

[0091] The above-mentioned cathode active material layer may include, for example, a cathode active material, a conductive material, a binder, and / or a solid electrolyte, and may additionally include additives in some cases.

[0092] The above-mentioned negative electrode active material may include, for example, lithium metal, lithium alloy, lithium metal composite oxide, lithium-containing titanium composite oxide (LTO), silicon, silicon alloy, and combinations thereof. Here, the lithium alloy may be an alloy composed of lithium and at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Al, and Sn. The lithium metal composite oxide may be an oxide (MeOx) of any one metal (Me) selected from the group consisting of lithium, Si, Sn, Zn, Mg, Cd, Ce, Ni, and Fe, and in one example, Li x Fe2O3(0 <x≤1) 또는 Li x WO2(0 <x≤1)일 수 있다. 음극활물질은 또한 예를 들어 Sn x Me 1-x Me y O z(Me:Mn,Fe,Pb,Ge;Me': Al, B, P, Si, Group 1, 2, and 3 elements of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 등의 금속 복합 산화물; SnO, SnO2,PbO,PbO2,Pb2O3,Pb3O4,Sb2O3,Sb2O4,Sb2O5,GeO,GeO2,Bi2O3,Bi2O4및 Bi2O5등의 산화물 등을 포함할 수 있고, 결정질 탄소, 비정질 탄소 또는 탄소 복합체와 같은 탄소계 음극활물질이 단독으로 또는 2종 이상이 포함될 수 있다.

[0093] Examples of the above conductive materials include nickel powder, cobalt oxide, titanium oxide, carbon, etc. As for carbon, any one or more selected from the group consisting of Ketjen black, acetylene black, furnace black, graphite, carbon fiber, and fullerene may be cited.

[0094] The above-mentioned cathode binder is, for example, any one selected from the group consisting of N,N-bis[3-(triethoxysilyl)propyl]urea, polyethylene oxide (PEO), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP), conjugated diene rubber latex such as styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), methyl butadiene methacrylate rubber (MBR), and butadiene rubber (BR), carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, and various copolymers, or a mixture of two or more of these. It is possible.

[0095] The solid electrolyte included in the negative electrode active material layer may be the same as or different from the solid electrolyte included in the aforementioned positive electrode active material layer and / or solid electrolyte layer.

[0096] In this specification, the term "non-cathode coating layer" refers to a coating layer formed between a negative electrode current collector and a solid electrolyte layer in an all-solid-state secondary battery in which lithium is adsorbed in the non-cathode coating layer during charging and, after the charging capacity of the non-cathode coating layer is exceeded, lithium is precipitated between the negative electrode current collector and the non-cathode coating layer to form a metal layer, and during discharge, lithium in the non-cathode coating layer and the lithium metal layer is ionized and moves toward the positive electrode. The composition and operating mechanism may differ from the aforementioned negative electrode active material layer. The non-cathode coating layer can cover the lithium metal layer during the charging process and / or immediately after battery manufacturing to serve as a protective layer for the lithium metal layer and can suppress the precipitation growth of lithium dendrites. Through this, short circuits and capacity degradation of the all-solid-state secondary battery can be suppressed and performance, etc., improved.

[0097] The above-mentioned anode coating layer may include, for example, amorphous carbon. The amorphous carbon included in the above-mentioned anode coating layer may be, for example, one or more types selected independently from the group consisting of carbon black, acetylene black, furnace black, Ketjen black, and graphene, but is not limited thereto, and any amorphous carbon that can be used in an anode all-solid-state secondary battery may be used without limitation.

[0098] The above-mentioned non-cathode coating layer may further include, for example, a lithium-affinity element that forms an alloy or compound with lithium. The lithium-affinity element may be, for example, one or more metals, metalloids, or combinations thereof selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn).

[0099] The particle size of the above lithium-affinity element may be, for example, within a range of 10 to 1000 nm. The above particle size may refer to a maximum particle size, a minimum particle size, or an average particle size. In other examples, the particle size of the above lithium-affinity element may be 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more, or 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, or 100 nm or less.

[0100] The above-mentioned non-cathode coating layer may also further include, for example, a binder. The binder for the above-mentioned non-cathode coating layer may be selected from the binders mentioned as being included in the aforementioned anode composite layer, cathode active material layer, and solid electrolyte layer, etc., or any known binder may be used without limitation without being limited thereto.

[0101] When an all-solid-state secondary battery includes a negative electrode coating layer, the all-solid-state secondary battery may further include a thin film containing an element capable of forming an alloy with lithium, for example. The thin film may be included between the negative electrode current collector and the negative electrode coating layer. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not limited thereto; any element capable of forming an alloy with lithium in the relevant technical field may be used. The thin film may be composed of one of the above examples or may be composed of various types of alloys. As the all-solid-state secondary battery of the present invention further includes such a thin film, the cycle characteristics of the all-solid-state secondary battery may be further improved.

[0102] The thickness of the thin film may be, for example, 1 to 800 nm, 10 to 700 nm, 50 to 600 nm, or 100 to 500 nm. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc., but is not limited thereto, and any method capable of forming a thin film in the relevant technical field is possible.

[0103] When including the above-mentioned anode coating layer, the all-solid-state secondary battery may further include, for example, a metal comprising lithium or a lithium alloy and / or a metal layer thereof between the negative electrode current collector and the anode coating layer, on the side of the anode coating layer opposite to the solid electrolyte layer, and / or within the anode coating layer. The lithium alloy may be, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but is not limited thereto; any alloy used as a lithium alloy in the relevant technical field is acceptable. The metal or metal layer included between the negative electrode current collector and the anode coating layer and / or within the anode coating layer may be composed of one of these alloys or lithium, or may be composed of various types of alloys.

[0104] The thickness of the metal layer containing the lithium or lithium alloy may be, for example, within the range of 1 to 1000 μm, 1 to 500 μm, 1 to 200 μm, 1 to 150 μm, 1 to 100 μm, or 1 to 50 μm. It is necessary to control the thickness as above so that the metal layer can perform its role as a lithium reservoir effectively and improve cycle characteristics.

[0105] The above metal layer may be formed, for example, by precipitation between the negative electrode current collector and the non-negative electrode coating layer, or on the side of the non-negative electrode coating layer opposite to the solid electrolyte layer, through charging after assembly of the all-solid-state secondary battery. When the metal layer is formed by charging after assembly of the all-solid-state secondary battery, the region between the negative electrode current collector and the non-negative electrode coating layer, or on the side of the non-negative electrode coating layer opposite to the solid electrolyte layer, may, for example, be a lithium-free region that does not contain lithium in the initial state or after discharge of the all-solid-state secondary battery. In another example, the above metal layer may be placed between the non-negative electrode coating layer and the negative electrode current collector during battery manufacturing, where lithium in the non-negative electrode coating layer and the lithium metal layer is ionized and moves toward the positive electrode during discharge, and is formed by lithium being precipitated again between the negative electrode current collector and the non-negative electrode coating layer after the charging capacity of the non-negative electrode coating layer is exceeded during charging.

[0106] Examples of additives that may be included in the above-mentioned cathode composite layer include fillers, coating agents, dispersants, and ion conductivity aids. Known materials generally used in electrodes of all-solid-state secondary batteries may be used as fillers, coating agents, dispersants, and ion conductivity aids that may be included in the cathode composite layer.

[0107] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and may include, for example, stainless steel, copper, nickel, titanium, calcined carbon, or stainless steel surface treated with carbon, nickel, titanium, silver, etc.

[0108] The above all-solid-state secondary battery may be, for example, a cylindrical secondary battery, a prismatic secondary battery, and / or a pouch-type secondary battery.

[0109] For example, when the secondary battery of the present invention is a cylindrical secondary battery, the all-solid-state secondary battery may include a battery can containing at least one structure and / or buffer pad, etc., and a cap assembly that seals the open end of the battery can. For each of the cylindrical battery can and the cap assembly, known provisions may be applied in the same manner as long as they do not impede the purpose of the present invention. The cap assembly may be electrically connected to the structure, for example, through an electrode tab (e.g., a positive tab) extending from the structure. Alternatively, it may be implemented as a tab-less structure. The tab-less structure may be, for example, a structure in which the positive current collector layer and the negative current collector layer included in the structure each include a non-circulating portion, and each of the non-circulating portions is electrically connected to an electrode terminal.

[0110] For example, if the secondary battery of the present invention is a prismatic secondary battery, the all-solid-state secondary battery may further include a prismatic case that accommodates at least one structure and / or buffer pad, and a base plate mounted on the top of the prismatic case. For each of the base plate and the prismatic case, known provisions may be applied in the same manner as long as they do not impede the purpose of the present invention. The base plate may, for example, have an electrode terminal protruding from the center that is connected to an electrode tab (e.g., a negative electrode tab) of the structure, but is not limited thereto. Alternatively, it may be implemented as a tab-less structure depending on the case. The tab-less structure may, for example, be a structure in which the positive current collector layer and the negative current collector layer included in the structure each include a non-circulating portion, and each of the non-circulating portions is electrically connected to an electrode terminal.

[0111] For example, if the arch battery of the present invention is a pouch-type secondary battery, the all-solid-state secondary battery may further include a pouch-type case that accommodates at least one structure and / or a buffer pad, etc. The pouch-type case may be manufactured by molding a pouch film laminate. In this case, the pouch film laminate may include a substrate layer, a gas barrier layer, and a sealant layer. In the pouch film laminate, the substrate layer, the gas barrier layer, and the sealant layer may be sequentially laminated.

[0112] The above substrate layer is formed, for example, on the outermost layer of a pouch film laminate to protect the secondary battery from friction and collision with the outside, and is made of a polymer to electrically insulate the structure from the outside.

[0113] The above substrate layer may be composed of one or more materials selected from the group consisting of, for example, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. Preferably, the substrate layer may be composed of polyethylene terephthalate (PET), nylon, or a combination thereof having wear resistance and heat resistance.

[0114] The above substrate layer may have a single-film structure composed of, for example, any one material. In another example, the above substrate layer may have a composite-film structure formed by two or more materials forming separate layers.

[0115] The thickness of the substrate layer may be, for example, 5 μm to 50 μm, specifically 7 μm to 40 μm, more specifically 25 μm to 38 μm. When the thickness of the substrate layer satisfies the above range, the external insulation is excellent, and the overall thickness of the pouch is not thick, so the energy density relative to the volume of the secondary battery may be excellent.

[0116] The above gas barrier layer may be laminated between the substrate layer and the sealant layer to secure the mechanical strength of the pouch, block the entry and exit of gases or moisture from outside the secondary battery, and prevent electrolyte leakage from inside the pouch-type case.

[0117] The above gas barrier layer can be formed of, for example, a metal, and specifically, can be formed of an aluminum alloy thin film. When a gas barrier layer is formed using an aluminum alloy thin film, it is possible to secure mechanical strength above a certain level, while also ensuring light weight, complementary electrochemical properties due to the structure, and heat dissipation. The above aluminum alloy thin film may include one or more metal elements other than aluminum (Al), selected from the group consisting of, for example, iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), silicon (Si), and zinc (Zn).

[0118] The thickness of the gas barrier layer may be, for example, 40 μm to 100 μm, specifically 50 μm to 90 μm, more specifically 55 μm to 85 μm. When the thickness of the gas barrier layer satisfies the above range, the moldability and gas barrier performance may be excellent during cup molding.

[0119] The above sealant layer may be intended to completely seal the interior of a pouch-type case by mutually thermally bonding at the sealing portion when, for example, a pouch-type case accommodating a structure on the inside is sealed. To this end, the sealant layer may be formed of a material having excellent thermal bonding strength.

[0120] The sealant layer may be formed from a material having insulating, corrosion-resistant, and sealing properties. Since the sealant layer must completely seal the inside of the pouch-type case to block material transfer between the inside and the outside, it may be formed from a material having high sealing properties (e.g., excellent thermal bonding strength). The sealant layer may be formed from a polymer material, for example. For example, the sealant layer may include polypropylene, but is not limited thereto.

[0121] The sealant layer may be composed of one or more materials selected from the group consisting of, for example, polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber, and preferably may be composed of a polyolefin resin such as polypropylene (PP) and / or polyethylene (PE). In this case, the polypropylene may be composed of cast polypropylene (CPP), acid-modified polypropylene (PPA), polypropylene-ethylene copolymer, and / or polypropylene-butylene-ethylene terpolymer.

[0122] The thickness of the sealant layer may be, for example, 30 μm to 130 μm, specifically 50 μm to 120 μm, and more specifically 70 μm to 100 μm. When the thickness of the sealant layer satisfies the above range, it has the effect of ensuring the sealing strength of the sealing portion while also ensuring the moldability of the pouch film laminate.

[0123] The pouch film laminate can be drawn and stretched by means of a punch or the like for the manufacture of a pouch-type case. As a result, the pouch-type case may include a cup portion and a receiving portion. The receiving portion is a place for housing a structure and may refer to a receiving space formed in the shape of a pocket inside the cup portion as the cup portion is formed.

[0124] The above pouch-type case can be sealed while housing a structure such that, for example, a part of the electrode lead, i.e., the terminal portion, is exposed. For example, the electrode lead can be connected to the electrode tab or the electrode-free portion of the structure.

[0125] A second aspect of the present invention may be a method for manufacturing an all-solid-state secondary battery having at least one structure (1) comprising a unit cell and a frame surrounding the outer surface of the unit cell.

[0126] The details regarding the first aspect of the present invention may be applied in the same way to the details regarding the second aspect unless specifically described otherwise.

[0127] The method for manufacturing an all-solid-state secondary battery of the present invention may include, for example, a step (step S1) of manufacturing a structure having a unit cell (10) comprising at least one each of a positive current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, and a negative current collector layer, and a frame (20) covering the outer surface of the unit cell.

[0128] In one example, the above S1 step may include a step of manufacturing a unit cell (10) by sequentially stacking an anode current collector layer, an anode composite layer, a solid electrolyte layer, a cathode composite layer, and a cathode current collector layer along the height direction (S11 step); and a step of forming a frame (20) to surround the outer surface of the unit cell (S12 step).

[0129] In another example, the above step S11 may be replaced with a step of manufacturing a unit cell by sequentially stacking a negative current collector layer, a negative composite layer, a solid electrolyte layer, an anode composite layer, an anode current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, and a negative current collector layer along the height direction (step S11'), or a step of manufacturing a unit cell by sequentially stacking a positive current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, a negative current collector layer, a negative composite layer, a solid electrolyte layer, a positive composite layer, and a positive current collector layer along the height direction (step S11'').

[0130] In the final manufactured unit cell of the steps S11, S11', and S11'' above, the stacking order of each layer, etc., may be performed in various ways as needed. Step S11 may, in one example, include, but is not limited to, the step of forming a first assembly in which a negative composite layer is formed on a negative current collector and then a solid electrolyte layer is formed on the negative composite layer, the step of forming a second assembly in which an anode composite layer is formed on an anode current collector, and the step of stacking the first assembly and the second assembly such that the solid electrolyte layer of the first assembly and the anode composite layer of the second assembly are in contact. Step S11' may, in one example, include the step of forming a first assembly in which a cathode composite layer is formed on a cathode current collector layer and then a solid electrolyte layer is formed on the cathode composite layer; the step of forming a second assembly in which an anode composite layer is formed on each side of an anode current collector; and the step of sequentially stacking the first assembly, the second assembly, and the third assembly so that the solid electrolyte layer of the first assembly and the anode composite layer of the second assembly are in contact, but is not limited thereto. Step S11'' may, in one example, include the step of forming a first assembly in which an anode composite layer is formed on an anode current collector layer and then a solid electrolyte layer is formed on the anode composite layer; the step of forming a second assembly in which a cathode composite layer is formed on each side of a cathode current collector; and the step of sequentially stacking the first assembly, the second assembly, and the third assembly so that the solid electrolyte layer of the first assembly and the cathode composite layer of the second assembly are in contact, but is not limited thereto.

[0131] Step S12 above may be performed, for example, by placing the frame to wrap the outer surface of the unit cell and then curing it by applying heat, when the frame is in the form of a film. Step S12 above may also be performed, for example, by applying the polymer resin inside the aforementioned cylindrical, prismatic, and / or pouch-type case, inserting the structure, vacuum sealing, and curing it by applying heat, when the frame is formed by a polymer resin, for example. However, Step S12 is not limited to the above, and methods known in the art may be applied without limitation as long as they do not impede the purpose of the present invention.

[0132] The above steps S11 (or S11', or S11'') and S12 may be performed, for example, simultaneously or at different times. For example, step S12 may be performed after step S11 (or step S11' or step S11'') is performed, or in some cases, step S12 may be performed while step S11 (or step S11' or step S11'') is being performed.

[0133] The method for manufacturing an all-solid-state secondary battery according to the present invention may include, for example, a step (step S2) of isostatically pressurizing the structure (1). The isostatic pressurization may be, for example, Warm Isostatic Pressure (WIP), or may be performed using a known isostatic pressurization method performed during the manufacturing process of an all-solid-state secondary battery. For example, since the structure must be protected from an isostatic pressurization medium such as water or gas during isostatic pressurization, the method may be performed by sealing it in a disposable pouch or the like before pressurizing, and then removing the disposable pouch after isostatic pressurization, but is not limited thereto.

[0134] The method for manufacturing an all-solid-state secondary battery of the present invention may further include, for example, a step (step S3) of introducing a buffer pad on at least one surface of the structure (1). The step S3 may be performed, for example, after step S2.

[0135] The method for manufacturing an all-solid-state secondary battery of the present invention may further include, for example, the step of stacking a plurality of the above-mentioned structures (1) in the height direction, in which case a buffer pad (30) may be introduced between each of the adjacent structures (1), and a buffer pad (30) may also be introduced on each of the outermost surfaces of the plurality of structures (1).

[0136] In addition, known methods used in the manufacture of all-solid-state secondary batteries may be used without limitation, provided that they do not impede the purpose of the present invention.

[0137] In the following, the present invention is described in detail with reference to examples to specifically explain the disclosure of the present invention as described above and the intended functions and effects of the present invention. However, the examples may be modified in various different forms, and the scope of this specification is not to be interpreted as being limited only to these examples. It is emphasized that the examples are provided to represent the present invention and to explain it more specifically to those skilled in the art.

[0138] Example 1.

[0139] Manufacturing of unit cells

[0140] (Cathode layer)

[0141] 6 g of carbon black (average particle size 41 nm), 2 g of silver (Ag) nanoparticles (average particle size 60 nm), 9.33 g of PVdF solution (solid content 6%), and 7.19 g of NMP solution were placed in a Thinky mixer container and mixed 12 times for 3 minutes at 2000 rpm. Subsequently, 5 g of NMP solution was added, and mixing was performed 5 times for 3 minutes at 2000 rpm to prepare a cathode-free coating layer slurry. Next, the slurry was coated onto a 10 µm thick SUS foil using a bar coater, dried in air at 80°C for 20 minutes, and then vacuum dried at 100°C for 12 hours. Through this process, a cathode layer with a cathode-free coating layer formed on the SUS foil was obtained.

[0142] (Bipolar layer)

[0143] LiNi as the positive active material 0.8 Co 0.15 Mn 0.05 O2 (NCM), Li6PS5Cl, an Argyrodite-type crystal, as the solid electrolyte, polytetrafluoroethylene (Teflon binder, DuPont) as the binder, and carbon nanofiber (CNF) as the conductive material were prepared. Then, these materials were mixed in a weight ratio of positive active material : solid electrolyte : conductive material : binder = 83.8 : 14.8 : 0.2 : 1.2, and the mixture was formed into a large sheet to produce a positive composite layer. Subsequently, this positive composite layer was pressed onto both sides of a 10㎛ thick aluminum foil positive current collector to produce a positive layer.

[0144] (Solid electrolyte layer)

[0145] The solid electrolyte layer used contained Li6PS5Cl solid electrolyte.

[0146] (Unit cell)

[0147] A cathode layer, a solid electrolyte layer, an anode layer, a solid electrolyte layer, and a cathode layer were sequentially stacked, and a frame was placed around the cathode layer, solid electrolyte layer, anode layer, solid electrolyte layer, and cathode layer to surround them. A flame-retardant inert material was used as the frame and introduced in the form of a film; two frames were introduced per unit cell to surround the cathode-free coating layer, the solid electrolyte layer, and the anode composite layer. The thickness of the frame in the direction perpendicular to the height direction was 180 μm. The areas of the anode composite layer, the solid electrolyte layer, and the cathode composite layer were the same.

[0148] The prepared unit cell was sealed in a pouch under vacuum and then subjected to isotropic pressurization at 85°C and 500 MPa for 30 minutes. In the unit cell manufactured after isotropic pressurization, the thickness of each non-cathode coating layer was 10 μm, the thickness of each anode composite layer was 120 μm, and the thickness of each solid electrolyte layer was 50 μm.

[0149] Manufacturing of all-solid-state secondary batteries

[0150] Six all-solid-state unit cells were prepared by removing the pouch after isotropic pressurization treatment. While stacking each of the above all-solid-state unit cells, a buffer pad with an elastic modulus of 2 GPa and a thickness of 200 μm was introduced between each adjacent all-solid-state unit cell. Then, the stacked structure was placed in a pouch and vacuum sealed to manufacture an all-solid-state secondary battery. A portion of the positive electrode current collector and the negative electrode current collector were protruded outside the sealed battery and used as positive layer terminals and negative layer terminals.

[0151] Evaluation example.

[0152] The all-solid-state secondary battery of the example was operated under the following charge-discharge conditions at an operating voltage range of 4.25V-3.0V and an operating temperature of 60℃ to evaluate the capacity characteristics and Coulomb efficiency according to the cycle, and the results are shown in Fig. 9.

[0153] Charging conditions: 0.33C, 4.25V CC / CV, 0.1C cut-off

[0154] Discharge conditions: 0.33C, 3.0V, CC

Claims

1. An all-solid-state secondary battery having at least one structure comprising a unit cell and a frame surrounding the outer surface of the unit cell, The above unit cell comprises at least one each of an anode current collector layer, an anode composite layer, a solid electrolyte layer, a cathode composite layer, and a cathode current collector layer, and The above anode composite layer, solid electrolyte layer, and cathode composite layer are stacked in the height direction and have the same area as each other, and All-solid-state secondary battery characterized by satisfying the following condition 1: [Condition 1] (Unit cell thickness (excluding current collector layer thickness) / 2)×70% ≤ Thickness in the direction perpendicular to the height direction of the frame ≤ (Unit cell thickness (excluding current collector layer thickness) / 2)×130%.

2. In Paragraph 1, The above unit cell, along the height direction, A solid-state secondary battery characterized by sequentially including a positive current collector layer, a positive composite layer, a solid electrolyte layer, a negative composite layer, and a negative current collector layer.

3. In Paragraph 1, The above unit cell, along the height direction, positive current collector layer, A pair of positive composite layers arranged with the above positive current collector layer in between, A pair of solid electrolyte layers positioned between the above pair of anode composite layers, A pair of cathode composite layers disposed between the above pair of solid electrolyte layers, and A solid-state secondary battery characterized by including a pair of negative current collector layers arranged between the above pair of negative composite layers.

4. In Paragraph 1, The above unit cell, along the height direction, cathode current collector layer, A pair of cathode composite layers arranged with the above-mentioned cathode current collector layer in between, A pair of solid electrolyte layers positioned between the above pair of cathode composite layers, A pair of anode composite layers disposed between the above pair of solid electrolyte layers, and A solid-state secondary battery characterized by including a pair of positive current collector layers arranged between the pair of positive composite layers mentioned above.

5. In Paragraph 1, A solid-state secondary battery characterized by including a buffer pad on at least one surface of the above-mentioned structure.

6. In Paragraph 5, The above-described buffer pad is characterized by having an elastic modulus of 0.1 to 5 GPa, in an all-solid-state secondary battery.

7. In Paragraph 5, An all-solid-state secondary battery characterized in that the thickness of the above-mentioned buffer pad is 80% to 150% of the thickness in the direction perpendicular to the height direction of the frame.

8. In Paragraph 5, All-solid-state secondary battery characterized by the thickness of the buffer pad being 10 to 500 μm.

9. In Paragraph 1, It includes a plurality of structures stacked in the height direction, and A solid-state secondary battery characterized by including buffer pads between each of adjacent structures.

10. In Paragraph 9, A solid-state secondary battery characterized by further including a buffer pad on each of the outermost surfaces of a plurality of structures.

11. In Paragraph 5, A solid-state secondary battery characterized in that the area of ​​the above-mentioned buffer pad is the same as the area of ​​the structure.

12. In Paragraph 1, The above frame is a flame-retardant inert member comprising a matrix and a filler; or high All-solid-state secondary battery characterized by having an insulating layer comprising a molecule, or a composite of a polymer and an inorganic material.

13. In Paragraph 5, The above-described buffer pad is characterized by including an elastic material, in a solid-state secondary battery.

14. In Paragraph 13, The above elastic material is characterized by comprising polyurethane, polyacrylate, fluorinated polymer, natural rubber, spandex, butyl rubber, fluoroelastomer, elastomer, ethylene-propylene rubber (EPR), styrene-butadiene rubber (SBR), isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone rubber, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), neoprene, acrylic, copolymers thereof, or combinations thereof, in an all-solid-state secondary battery.

15. In Paragraph 1, A solid-state secondary battery characterized in that the above-mentioned solid electrolyte layer comprises a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte.

16. A method for manufacturing an all-solid-state secondary battery comprising at least one structure including a unit cell and a frame surrounding the outer surface of the unit cell, wherein A step of manufacturing a structure having a unit cell comprising at least one each of an anode current collector layer, an anode composite layer, a solid electrolyte layer, a cathode composite layer, and a cathode current collector layer, and a frame surrounding the outer surface of the unit cell (step S1); and The method includes the step of applying isotropic pressure to the above structure (step S2), and The above anode composite layer, solid electrolyte layer, and cathode composite layer are stacked in the height direction and have the same area as each other, and A method for manufacturing an all-solid-state secondary battery characterized by satisfying the following condition 1: [Condition 1] (Unit cell thickness (excluding current collector layer thickness) / 2)×70% ≤ Thickness in the direction perpendicular to the height direction of the frame ≤ (Unit cell thickness (excluding current collector layer thickness) / 2)×130%.

17. In Paragraph 16, A method for manufacturing an all-solid-state secondary battery, characterized by further including the step (step S3) of introducing a buffer pad on at least one surface of the above-mentioned structure.

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