Cathode for All solid secondary battery, All solid secondary battery comprising cathode and preparation method fo All solid battery

Abstract

A positive electrode for an all-solid-state secondary battery is provided, comprising a positive current collector and a positive active material layer containing a solid electrolyte on the positive current collector, wherein the positive current collector comprises a first surface adjacent to the positive active material layer and a second surface opposing the first surface, and the maximum surface roughness value (Ry) of the second surface of the positive current collector is 1.5 μm or more; an all-solid-state secondary battery including the same; and a method for manufacturing an all-solid-state secondary battery are provided.

Description

Technology Field

[0001] The invention relates to a positive electrode for an all-solid-state secondary battery, an all-solid-state secondary battery including the positive electrode, and a method for manufacturing an all-solid-state secondary battery. Background Technology

[0002] Recently, there has been active development of batteries that provide increased energy density and safety. Lithium batteries are used in information devices, communication devices, and automobiles. Safety is critical for automobiles because they are related to human life. Lithium batteries containing liquid electrolytes include flammable organic solvents. Lithium batteries containing liquid electrolytes have a high risk of overheating and fire in the event of a short circuit. Solid electrolytes have a reduced risk of overheating and fire in the event of a short circuit compared to liquid electrolytes. Lithium batteries containing solid electrolytes can provide enhanced safety compared to lithium batteries containing liquid electrolytes. The problem to be solved

[0003] One aspect is to provide a positive electrode for an all-solid-state secondary battery having reduced porosity by uniformly applying pressure.

[0004] One aspect is to provide an all-solid-state secondary battery having reduced internal resistance and improved charge / discharge characteristics by having a positive electrode having reduced porosity.

[0005] One aspect is to provide a method for manufacturing an all-solid-state secondary battery that enables uniform pressure application to the positive electrode. means of solving the problem

[0006] Depending on one aspect

[0007] It comprises a positive current collector and a positive active material layer containing a solid electrolyte on the positive current collector, and

[0008] The above positive current collector includes a first surface adjacent to the positive active material layer and a second surface opposing the first surface,

[0009] Maximum roughness (R) of the second surface of the above positive current collector y2A cathode for an all-solid-state secondary battery is provided, having a highest surface roughness value of 1.5 μm or more.

[0010] Depending on the other aspect

[0011] The above solid electrolyte layer includes an anode solid electrolyte layer disposed adjacent to the anode and a cathode solid electrolyte layer disposed adjacent to the cathode, and

[0012] An all-solid-state secondary battery is provided in which the porosity of the positive electrode solid electrolyte layer is lower than the porosity of the negative electrode solid electrolyte layer.

[0013] According to another aspect,

[0014] A step of preparing an anode-solid electrolyte laminate by applying a first pressurization to the anode and the solid electrolyte layer together with a first pressurization auxiliary layer; and

[0015] A method for manufacturing an all-solid-state secondary battery is provided, comprising the step of preparing an all-solid-state secondary battery by applying a second pressurization to the anode-solid electrolyte laminate and the cathode-solid electrolyte laminate together with a second pressurization auxiliary layer.

[0016] According to another aspect,

[0017] A method for manufacturing an anode is provided, comprising the step of pressurizing the anode together with a pressurizing auxiliary layer. Effects of the invention

[0018] According to one aspect, it is possible to provide a new all-solid-state secondary battery anode having a reduced porosity by uniformly pressurizing.

[0019] According to one aspect, it is possible to provide an all-solid-state secondary battery having reduced internal resistance and improved charge / discharge characteristics by providing a positive electrode having reduced porosity.

[0020] According to one aspect, a method for manufacturing an all-solid-state secondary battery is provided that enables uniform pressure application of the positive electrode. Brief explanation of the drawing

[0021] FIG. 1 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to one embodiment. FIG. 2 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to the prior art. FIG. 3 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to one embodiment. FIG. 4 is a schematic cross-sectional view of an all-solid-state secondary battery (100) according to one embodiment. FIG. 5a is a schematic cross-sectional view of a positive electrode used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5b is a schematic cross-sectional view of a solid electrolyte layer / protection layer laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5c is a schematic cross-sectional view of a first pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5d is a schematic cross-sectional view of a positive-solid electrolyte laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6a is a schematic cross-sectional view of a negative electrode used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6b is a schematic cross-sectional view of a solid electrolyte layer / protection layer laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6c is a schematic cross-sectional view of a first pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6d is a schematic cross-sectional view of a negative electrode-solid electrolyte laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 7a is a schematic cross-sectional view of a second pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 7b is a schematic cross-sectional view of an all-solid-state secondary battery manufactured by a manufacturing method according to one embodiment. FIG. 8 is a surface profile of the second surface of the positive current collector of the all-solid-state secondary battery prepared in Example 1 and Comparative Example 1. Figure 9 is a scanning electron microscope image of a cross-section of the positive electrode of the all-solid-state secondary battery prepared in Example 4. Figure 10 is a scanning electron microscope image of a cross-section of the positive electrode of the all-solid-state secondary battery prepared in Comparative Example 1. Specific details for implementing the invention

[0022] Various embodiments are illustrated in the accompanying drawings. However, the present creative concept may be embodied in many different forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided to ensure that the present disclosure is thorough and complete and will sufficiently convey the scope of the present creative concept to those skilled in the art. Identical reference numerals denote identical components.

[0023] When it is stated that one component is "on top" of another component, it can be understood that it may be directly on top of the other component or that another component may be interposed between them. In contrast, when it is stated that a component is "directly on top" of another component, no component is interposed between them.

[0024] Terms such as "first," "second," "third," etc., may be used in this specification to describe various components, components, regions, layers, and / or zones, but these components, components, regions, layers, and / or zones should not be limited by these terms. These terms are used solely to distinguish one component, component, region, layer, or zone from another. Accordingly, the first component, component, region, layer, or zone described below may be referred to as the second component, component, region, layer, or zone without departing from the teachings of this specification.

[0025] The terms used herein are intended to describe specific embodiments only and are not intended to limit the creative idea. The singular form used herein is intended to include the plural form including "at least one" unless the content clearly indicates otherwise. "At least one" should not be interpreted as limiting to the singular. As used herein, the term "and / or" includes any combination of one or more of the listed items. The terms "comprising" and / or "comprising" as used in the detailed description specify the presence of the specified features, regions, integers, steps, actions, components, and / or components, and do not exclude the presence or addition of one or more other features, regions, integers, steps, actions, components, components, and / or groups thereof.

[0026] Spatially relative terms such as "bottom," "lower," "subordinate," "top," "upper," and "upper" may be used herein to facilitate the description of the relationship of one component or feature to another component or feature. Spatially relative terms are to be understood as intended to include different orientations of the device during use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings is inverted, a component described as "bottom" or "lower" of another component or feature will be oriented to the "top" of that other component or feature. Thus, the exemplary term "bottom" may encompass both the upper and lower directions. The device may be positioned in different directions (it may be rotated 90 degrees or rotated in other directions), and spatially relative terms used herein may be interpreted accordingly.

[0027] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Furthermore, it will also be understood that terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning within the context of the relevant technology and the content of this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0028] Exemplary embodiments are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments. As such, variations from the depicted shapes should be expected as a result of, for example, manufacturing techniques and / or tolerances. Accordingly, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as depicted herein, but should include variations in shapes resulting from, for example, manufacturing. For example, a region depicted or described as flat may typically have rough and / or non-linear features. Furthermore, an angle depicted as sharp may be rounded. Accordingly, the regions depicted in the drawings are essentially schematic, and the shapes are not intended to depict the exact shape of the region and are not intended to limit the scope of the claims.

[0029] "Group" refers to a group of elements in the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system of groups 1-18.

[0030] In this specification, “particle diameter” refers to the average diameter when the particle is spherical and the average major axis length when the particle is non-spherical. The particle diameter can be measured using a particle size analyzer (PSA). “Particle diameter” is, for example, the average particle diameter. The “average particle diameter” is, for example, D50, the median particle diameter.

[0031] D50 is the particle size corresponding to 50% of the cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0032] D90 is the particle size corresponding to the 90% cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0033] D10 is the particle size corresponding to the 10% cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0034] In the present disclosure, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0035] In this disclosure, "alloy" means a mixture of two or more metals.

[0036] In the present disclosure, "electrode active material" refers to an electrode material capable of undergoing lithiation and delithiation.

[0037] In the present disclosure, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0038] In the present disclosure, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0039] In the present disclosure, "lithiation" and "to lithiate" refer to the process of adding lithium to an electrode active material.

[0040] In the present disclosure, "delithiation" and "to delithiate" refer to the process of removing lithium from an electrode active material.

[0041] In this disclosure, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0042] In this disclosure, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

[0043] In this disclosure, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0044] In this disclosure, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0045] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or cannot be anticipated may arise to the applicant or those skilled in the art. Accordingly, the appended claims, which may be filed and modified, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0046] A positive electrode for an all-solid-state secondary battery according to exemplary embodiments, an all-solid-state secondary battery including the same, and a method for manufacturing an all-solid-state secondary battery will be described in more detail below.

[0047] [anode]

[0048] A positive electrode for an all-solid-state secondary battery according to one embodiment comprises a positive electrode current collector and a positive electrode active material layer containing a solid electrolyte on the positive electrode current collector. The positive electrode current collector comprises a first surface adjacent to the positive electrode active material layer and a second surface opposing the first surface. The maximum roughness (R) of the second surface of the positive electrode current collector. y2 The highest surface roughness value is 1.5 μm or more.

[0049] By placing a flexible pressure-assisting layer on the positive current collector during pressurization for the manufacture of a positive electrode for an all-solid-state secondary battery, pressure can be uniformly transmitted along the surface contour of the positive electrode active material layer. For example, more pressure can be dispersed and transmitted to the solid electrolyte between the positive electrode active material particles constituting the positive electrode active material layer. Pressure sintering of the solid electrolyte placed between the positive electrode active material particles is promoted, reducing the voids between the particles and decreasing the porosity of the positive electrode active material layer. Consequently, the internal resistance of the all-solid-state secondary battery containing such a positive electrode can be reduced, and cycle characteristics can be improved. Furthermore, by placing a flexible pressure-assisting layer on the positive current collector during pressurization for the manufacture of a positive electrode for an all-solid-state secondary battery, pressure is uniformly transmitted to the positive current collector along the surface contour of the positive electrode active material layer. As a result, the surface contour of the positive electrode active material layer is transferred to a first surface adjacent to the positive electrode active material layer and a second surface facing the first surface, and the maximum roughness (R) of the second surface y ) increases to 1.5 μm or more. Maximum roughness (R y2 ) is the difference between the highest peak and the lowest valley in the surface profile measured for the second plane. In contrast, when a high-strength substrate is placed during the pressurization for manufacturing a cathode for a conventional all-solid-state secondary battery, pressure is preferentially transferred to the cathode active material particles and partially transferred to the solid electrolyte between the cathode active material particles. As a result, the pressurized sintering of the solid electrolyte placed between the cathode active materials is poor, which increases the voids between the cathode active material particles, thereby increasing the porosity of the cathode active material layer and increasing the internal resistance of the all-solid-state secondary battery containing such a cathode, and the cycle characteristics may deteriorate.

[0050] (Bipolar collector)

[0051] FIG. 1 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to one embodiment. In FIG. 1, the spherical particles of the positive electrode active material layer (12) are positive electrode active material particles, and a solid electrolyte is disposed between the positive electrode active material particles.

[0052] Referring to FIG. 1, a positive electrode (10) for an all-solid-state secondary battery comprises a positive electrode current collector (11) and a positive electrode active material layer (12) containing a solid electrolyte on the positive electrode current collector (11). The positive electrode current collector (11) includes a first surface (S11a) adjacent to the positive electrode active material layer (12) and a second surface (S11b) opposite to the first surface (S11a).

[0053] Maximum roughness (R) of the second surface (S11b) of the positive current collector y ) may be, for example, 1.5 μm or more, 2 μm or more, 2.5 μm or more, 3 μm or more, or 3.5 μm or more. The maximum roughness (R) of the second surface (S11b) of the positive current collector y ) may be, for example, 10 μm or less, 9 μm or less, 8 μm or less, or 7 μm or less. The maximum roughness (R) of the second surface (S11b) of the positive current collector y The highest surface roughness value) can be, for example, 1.5 μm to 10 μm, 2 μm to 9 μm, 2.5 μm to 8 μm, 3 μm to 7 μm, or 3.5 μm to 7 μm. The maximum roughness (R) of the second surface (S11b) of the anode current collector is y By having such a range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved. The maximum roughness (R) of the second surface (S11b) of the positive current collector y) can be measured, for example, using an optical microscope, a scanning electron microscope, etc. For example, the second surface (S11b) of the positive current collector can be observed with an optical microscope to derive a roughness profile of the surface of the positive current collector, and the maximum roughness can be measured from this. Alternatively, the maximum roughness of the second surface (S11b) of the positive current collector can be measured by measuring the surface profile with a scanning microscope on the cross-section of the positive electrode (10).

[0054] Maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) may be, for example, 1.0 μm or more, 1.5 μm or more, 2 μm or more, 2.5 μm or more, or 3 μm or more. The maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) may be, for example, 10 μm or less, 9 μm or less, 8 μm or less, or 7 μm or less. The maximum roughness (R) of the first surface (S11a) of the anode current collector y1 ) may be, for example, 1.0 μm to 10 μm, 1.5 μm to 9 μm, 2 μm to 8 μm, 2.5 μm to 7 μm, or 3 μm to 7 μm. The maximum roughness (R) of the first surface (S11a) of the anode current collector y1 By having this range, the porosity of the positive active material layer (12) can be reduced more effectively. The maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) can be measured, for example, using an optical microscope, a scanning electron microscope, etc. For example, the maximum roughness of the first surface (S11a) of the positive current collector can be measured by measuring the surface profile of the cross-section of the positive electrode (10) with a scanning electron microscope. Alternatively, the positive active material layer (12) can be removed from the positive electrode (10), and the first surface (S11a) of the positive current collector can be observed with an optical microscope to derive the roughness profile of the surface of the positive current collector, from which the maximum roughness of the first surface (S11a) of the positive current collector can be measured. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0055] Maximum roughness (R) of the second surface (S11b) of the positive current collector y2 ) may be, for example, 15% or more, 20% or more, or 25% or more of the anode current collector thickness (T11). The maximum roughness (R) of the second surface (S11b) of the anode current collector y2 ) may be, for example, 60% or less, 55% or less, or 50% or less of the anode current collector thickness (T11). The maximum roughness (R) of the second surface (S11b) of the anode current collector y2 ) may be, for example, 15 to 60%, 20 to 55%, or 25 to 50% of the anode current collector thickness (T11). The maximum roughness (R) of the second surface (S11b) of the anode current collector y2 By having such a range, the porosity of the positive active material layer (12) can be reduced more effectively. The positive current collector thickness (T11) may be the average thickness of the positive current collector. The average thickness of the positive current collector may be the average value of the vertical distance between the first surface and the second surface at 10 selected points on the entire positive current collector. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved.

[0056] Maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) may be, for example, 5% or more, 10% or more, or 15% or more of the anode current collector thickness (T11). The maximum roughness (R) of the first surface (S11a) of the anode current collector y1 ) may be, for example, 70% or less, 65% or less, or 60% or less of the anode current collector thickness (T11). The maximum roughness (R) of the first surface (S11a) of the anode current collector y1 ) may be, for example, 5 to 70%, 10 to 65%, or 15 to 60% of the anode current collector thickness (T11). The maximum roughness (R) of the first surface (S11a) of the anode current collector y1By having such a range, the porosity of the positive active material layer (12) can be reduced more effectively. The positive current collector thickness (T11) may be the average thickness of the positive current collector. The average thickness of the positive current collector may be the average value of the vertical distance between the first surface and the second surface at 10 selected points on the entire positive current collector. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved.

[0057] Maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) is the maximum roughness (R) of the second surface (S11b) of the positive current collector y2 It can be larger than ). Maximum roughness (R) of the first surface (S11a) of the anode current collector y ) and the maximum roughness (R) of the second surface (S11b) of the positive current collector y Ratio of ) y1 / R y2 ) may be, for example, 1.01 or greater, 1.05 or greater, or 1.10 or greater. The maximum roughness (R) of the first surface (S11a) of the positive current collector y ) and the maximum roughness (R) of the second surface (S11b) of the positive current collector y Ratio of ) y1 / R y2 ) may be, for example, 2 or less, 1.5 or less, or 1.3 or less. The maximum roughness (R) of the first surface (S11a) of the positive current collector y ) and the maximum roughness (R) of the second surface (S11b) of the positive current collector y Ratio of ) y1 / R y2 ) can be, for example, 1.01 to 2, 1.05 to 1.5, or 1.10 to 1.3. The maximum roughness (R) of the first surface (S11a) of the anode current collector y ) and the maximum roughness (R) of the second surface (S11b) of the positive current collector y Ratio of ) y1 / R y2By having such a range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0058] The thickness (T11) of the positive current collector is, for example, 2 μm to 100 μm, 4 μm to 50 μm, 5 μm to 30 μm, or 5 μm to 20 μm. By having the positive current collector (11) have a thickness within this range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved. The positive current collector (11) may include, for example, aluminum (Al), indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), germanium (Ge), lithium (Li), or an alloy thereof.

[0059] The first surface (S11a) and the second surface (S11b) of the positive current collector may each include an uneven surface, for example, including a convex and a concave portion. By including the first surface (S11a) and the second surface (S11b) of the positive current collector, for example, an uneven surface, including a convex and a concave portion, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0060] The positive active material layer (12) may, for example, have a first positive active material layer depression (CC12). The first surface (S11a) of the positive current collector may have a first positive current collector protrusion (CV11a) that protrudes in the direction of the positive active material layer (12) corresponding to the first positive active material layer depression (CC12). The second surface (S11b) of the positive current collector may have a first positive current collector depression (CC11b) that is depressed in the direction of the positive active material layer (12) corresponding to the first positive current collector protrusion (CV11a).

[0061] In the thickness direction (i.e., z-direction) of the positive current collector, at least a portion of the area (AA11a) occupied by the first positive current collector protrusion (CV11a) of the first surface (S11a) of the positive current collector may overlap with at least a portion of the area (AA11b) occupied by the first positive current collector recess (CC11b) of the second surface (S11b) of the positive current collector. By overlapping at least a portion of the area (AA11a) occupied by the first positive current collector protrusion (CV11a) of the first surface (S11a) of the positive current collector with at least a portion of the area (AA11b) occupied by the first positive current collector recess (CC11b) of the second surface (S11b) of the positive current collector, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved. The area (AA11a) occupied by the first positive current collector protrusion (CV11a) on the first surface (S11a) of the positive current collector is, for example, the area occupied by the first positive current collector protrusion (CV11a) in the plan view of the positive current collector. The area (AA11b) occupied by the first positive current collector recess (CC11b) on the second surface (S11b) of the positive current collector is, for example, the area occupied by the first positive current collector recess (CC11b) in the plan view of the positive current collector.

[0062] The cross-sectional shape of the first positive current collector recess (CC11b) on the second surface (S11b) of the positive current collector may correspond, for example, to the cross-sectional shape of the first positive current collector protrusion (CV11a) on the first surface (S11a) of the positive current collector. The cross-sectional shape of the first positive current collector recess (CC11b) on the second surface (S11b) of the positive current collector may, for example, have a shape that is a transfer of the first positive current collector protrusion (CV11a) on the first surface (S11a) of the positive current collector. The cross-sectional shape of the first positive current collector recess (CC11b) on the second surface (S11b) of the positive current collector may, for example, have a shape similar to or identical to the cross-sectional shape of the first positive current collector protrusion (CV11a) on the first surface (S11a) of the positive current collector. By having the cross-sectional shape of the first positive current collector recess (CC11b) of the second surface (S11b) of the positive current collector correspond to the cross-sectional shape of the first positive current collector protrusion (CV11a) of the first surface (S11a) of the positive current collector, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0063] The radius of curvature (RCC11b) of the cross-section of the first positive current collector recess (recess) on the second surface (S11b) of the positive current collector may be larger than the radius of curvature (RCV11a) of the cross-section of the first positive current collector protrusion (recess) on the first surface (S11a) of the positive current collector. The ratio (RCC11b / RCV11a) of the radius of curvature (RCC11b) of the cross-section of the first positive current collector recess (recess) on the second surface (S11b) of the positive current collector and the radius of curvature (RCV11a) of the cross-section of the first positive current collector protrusion (recess) on the first surface (S11a) of the positive current collector may be, for example, greater than 1.0, 1.1 or more, 1.5 or more, or 2 or more. The ratio (RCC11b / RCV11a) of the radius of curvature of the first positive current collector recessed section cross-section of the second positive current collector surface (S11b) and the radius of curvature of the first positive current collector protruding section cross-section of the first positive current collector surface (S11a) may be, for example, 100 or less, 50 or less, 20 or less, or 10 or less. The ratio (RCC11b / RCV11a) of the radius of curvature of the first positive current collector recessed section cross-section of the second positive current collector surface (S11b) and the radius of curvature of the first positive current collector protruding section cross-section of the first positive current collector surface (S11a) may be, for example, greater than 1.0 to 100, 1.1 to 50, 1.5 to 20, or 2 to 10. By having the ratio (RCC11b / RCV11a) of the radius of curvature of the first positive current collector recessed section cross-section of the second positive current collector surface (S11b) and the radius of curvature of the first positive current collector protruding section cross-section of the first positive current collector surface (S11a) have such a range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0064] The radius of curvature (RCC11b) of the cross-section of the first positive current collector recess on the second surface (S11b) of the positive current collector may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 50 μm or less, or 10 μm or less. The radius of curvature (RCC11b) of the cross-section of the first positive current collector recess on the second surface (S11b) of the positive current collector may be, for example, 1 to 1000 μm, 1 to 500 μm, 1 to 100 μm, 1 to 50 μm or less, or 1 to 10 μm. By having the radius of curvature (RCC11b) of the cross-section of the first positive current collector recess on the second surface (S11b) of the positive current collector within this range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0065] The radius of curvature (RCV11a) of the cross-section of the first positive current collector protrusion on the first surface (S11a) of the positive current collector may be, for example, 900 μm or less, 500 μm or less, 100 μm or less, 50 μm or less, or 10 μm or less. The radius of curvature (RCV11a) of the cross-section of the first positive current collector protrusion on the first surface (S11a) of the positive current collector may be, for example, 1 to 900 μm, 1 to 500 μm, 1 to 100 μm, 1 to 50 μm or less, or 1 to 10 μm. By having the radius of curvature (RCV11a) of the cross-section of the first positive current collector protrusion on the first surface (S11a) of the positive current collector within this range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0066] The positive active material layer (12) may, for example, have a first positive active material layer protrusion (CV12). The first surface (S11a) of the positive current collector may have a second positive current collector recess (CC11a) that protrudes in the direction of the positive active material layer (12) corresponding to the first positive active material layer protrusion (CV12). The second surface (S11b) of the positive current collector may have a second positive current collector protrusion (CV11b) that recesses in the direction of the positive active material layer (12) corresponding to the second positive current collector recess (CC11a).

[0067] In the thickness direction (i.e., z-direction) of the positive current collector, at least a portion of the area (AB11a) occupied by the second positive current collector recess (CC11a) of the first surface (S11a) of the positive current collector may overlap with at least a portion of the area (AB11b) occupied by the second positive current collector protrusion (CC11a) of the second surface (S11b) of the positive current collector. By overlapping at least a portion of the area (AB11a) occupied by the second positive current collector recess (CC11a) of the first surface (S11a) of the positive current collector with at least a portion of the area (AB11b) occupied by the second positive current collector protrusion (CV11b) of the second surface (S11b) of the positive current collector, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved. The area (AB11a) occupied by the second positive current collector recess (CC11a) of the first surface (S11a) of the positive current collector is, for example, the area occupied by the second positive current collector recess (CC11a) in the plan view of the positive current collector. The area (AB11b) occupied by the second positive current collector protrusion (CV11b) of the second surface (S11b) of the positive current collector is, for example, the area occupied by the second positive current collector protrusion (CV11b) in the plan view of the positive current collector.

[0068] The cross-sectional shape of the second positive current collector protrusion (CV11b) on the second surface (S11b) of the positive current collector may correspond, for example, to the cross-sectional shape of the second positive current collector recess (CCV11a) on the first surface (S11a) of the positive current collector. The cross-sectional shape of the second positive current collector protrusion (CVC11b) on the second surface (S11b) of the positive current collector may have a shape that is, for example, a transferred shape of the second positive current collector recess (CC11a) on the first surface (S11a) of the positive current collector. The cross-sectional shape of the second positive current collector protrusion (CV11b) on the second surface (S11b) of the positive current collector may have a shape similar to or identical to the cross-sectional shape of the second positive current collector recess (CC11a) on the first surface (S11a) of the positive current collector. By having the cross-sectional shape of the second positive current collector protrusion (CV11b) of the second surface (S11b) of the positive current collector correspond to the cross-sectional shape of the second positive current collector depression (CC11a) of the first surface (S11a) of the positive current collector, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0069] The radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector may be larger than the radius of curvature (RCC11a) of the cross-section of the second positive current collector recess on the first surface (S11a) of the positive current collector. The ratio (RCV11b / RCC11a) of the radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector and the radius of curvature (RCC11a) of the cross-section of the second positive current collector recess on the first surface (S11a) of the positive current collector may be, for example, greater than 1.0, 1.1 or more, 1.5 or more, or 2 or more. The ratio (RCV11b / RCC11a) of the radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector and the radius of curvature (RCC11a) of the cross-section of the second positive current collector recess on the first surface (S11a) of the positive current collector may be, for example, 100 or less, 50 or less, 20 or less, or 10 or less. The ratio (RCV11b / RCC11a) of the radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector and the radius of curvature (RCC11a) of the cross-section of the second positive current collector recess on the first surface (S11a) of the positive current collector may be, for example, greater than 1.0 to 100, 1.1 to 50, 1.5 to 20, or 2 to 10. By having the ratio (RCV11b / RCC11a) of the radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector and the radius of curvature (RCC11a) of the cross-section of the second positive current collector depression on the first surface (S11a) of the positive current collector, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive (10) can be reduced and the cycle characteristics can be improved.

[0070] The radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector may be, for example, 1000 μm or less, 500 μm or less, 100 μm or less, 50 μm or less, or 10 μm or less. The radius of curvature (RCVC11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector may be, for example, 1 to 1000 μm, 1 to 500 μm, 1 to 100 μm, 1 to 50 μm or less, or 1 to 10 μm. By having the radius of curvature (RCV11b) of the cross-section of the second positive current collector protrusion on the second surface (S11b) of the positive current collector within this range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0071] The radius of curvature (RCC11a) of the cross-section of the second positive current collector recess of the first surface (S11a) of the positive current collector may be, for example, 900 μm or less, 500 μm or less, 100 μm or less, 50 μm or less, or 10 μm or less. The radius of curvature (RCCV11a) of the cross-section of the second positive current collector recess of the first surface (S11a) of the positive current collector may be, for example, 1 to 900 μm, 1 to 500 μm, 1 to 100 μm, 1 to 50 μm or less, or 1 to 10 μm. By having the radius of curvature (RCC11a) of the cross-section of the second positive current collector recess of the first surface (S11a) of the positive current collector within this range, the porosity of the positive active material layer (12) can be reduced more effectively. The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) can be reduced and the cycle characteristics can be improved.

[0072] A conductive coating layer may be absent on the positive current collector. The positive current collector may not include a conductive coating layer disposed on the first surface and the second surface. The conductive coating layer may be a coating layer comprising, for example, a carbon-based material.

[0073] The positive current collector (11) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The base film may be, for example, an insulator. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon a short circuit, thereby blocking battery operation and suppressing a sudden increase in current. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or an alloy thereof. The metal layer can act as an electrochemical fuse and be cut off upon overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal layer. The metal layer can be plated or deposited on the base film. As the thickness of the metal layer decreases, the limit current and / or maximum current of the positive current collector (11) decreases, thereby improving the stability of the lithium battery during a short circuit. A lead tab may be added to the metal layer for external connection. The lead tab may be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or metal layer melt, allowing the metal layer to be electrically connected to the lead tab. To make the weld between the metal layer and the lead tab more robust, a metal chip may be added between the metal layer and the lead tab.The metal chip may be a thin sheet of the same material as the metal of the metal layer. The metal chip may be, for example, a metal foil, a metal mesh, etc. The metal chip may be, for example, an aluminum foil, a copper foil, a SUS foil, etc. A lead tab may be welded to a metal chip / metal layer laminate or a metal chip / metal layer / base film laminate by placing the metal chip on the metal layer and then welding it to the lead tab. During welding, the base film, the metal layer, and / or the metal chip may melt, and the metal layer or the metal layer / metal chip laminate may be electrically connected to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal layer. The thickness of the base film may be, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. By having the base film have a thickness within this range, the weight of the electrode assembly (40, 40a, 40b) can be reduced more effectively. The melting point of the base film may be, for example, 100 to 300 °C, 100 to 250 °C or lower, or 100 to 200 °C. Since the base film has a melting point within this range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. Surface treatments, such as corona treatment, may be performed on the base film to improve the adhesion between the base film and the metal layer. The thickness of the metal layer may be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. Since the metal layer has a thickness within this range, the stability of the electrode assembly (40, 40a, 40b) can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. Since the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be performed more easily.By having the positive current collector (11) have this structure, the weight of the positive electrode is reduced, and consequently, the energy density of the positive electrode and the all-solid-state secondary battery (100) can be improved.

[0074] FIG. 2 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to the prior art. In FIG. 2, the spherical particles of the positive electrode active material layer (12) are positive electrode active material particles, and a solid electrolyte is disposed between the positive electrode active material particles.

[0075] Referring to FIG. 2, a positive electrode (10) for an all-solid-state secondary battery comprises a positive electrode current collector (11) and a positive electrode active material layer (12) containing a solid electrolyte on the positive electrode current collector (11). The positive electrode current collector (11) comprises a first surface (S11a) adjacent to the positive electrode active material layer (12) and a second surface (S11b) opposing the first surface (S11a). The maximum roughness (R) of the second surface (S11b) of the positive electrode current collector y2 ) is, for example, less than 1.5 μm. When manufacturing a positive electrode (10) for an all-solid-state secondary battery according to the prior art, the surface contour of the positive electrode active material layer (12) is not transferred to the second surface (S11b) of the positive electrode current collector when pressed by a hard roller, so the maximum roughness (R) of the second surface (S11b) is y2 ) is reduced. In addition, as the surface contour of the positive active material layer (12) is not sufficiently transferred to the first surface (S11a) of the positive current collector, the maximum roughness (R) of the first surface (S11a) is reduced. y1 ) also decreases. The maximum roughness (R) of the first surface (S11a) of the positive current collector y1 ) is, for example, less than 1.0 μm. The maximum roughness (R) of this second surface (S11b) of the positive current collector (11) y2 ) and the maximum roughness (R) of the first surface (S11a) y1 It may be difficult to reduce the porosity of the positive active material layer (12) by having such a positive electrode (10). The internal resistance of the all-solid-state secondary battery (100) including such a positive electrode (10) may increase and the cycle characteristics may deteriorate.

[0076] (Cathode active material layer)

[0077] FIG. 3 is a schematic cross-sectional view of a positive electrode for an all-solid-state secondary battery according to one embodiment.

[0078] Referring to FIGS. 1 and FIGS. 3, the positive electrode (10) for an all-solid-state secondary battery includes a positive electrode current collector (11) and a positive electrode active material layer (12).

[0079] The positive active material layer (12) may have, for example, reduced porosity.

[0080] The porosity is the ratio of the area occupied by pores to the total area excluding the area of ​​the positive active material in the scanning electron microscope image of the cross-section of the anode (10). The porosity can be measured, for example, from the scanning electron microscope image of the cross-section of the positive active material layer (12). The anode (10) includes a positive current collector and a positive active material, and the porosity of the positive active material layer may be, for example, 14% or less, 10% or less, 8% or less, or 5% or less. By having a porosity within this range, the internal resistance of the positive active material layer (12) can be further reduced and the ion conductivity of the positive active material layer (12) can be improved. The energy density and cycle characteristics of the all-solid-state secondary battery (100) including such an anode (10) can be improved.

[0081] (Cathode active material)

[0082] The positive active material layer (12) includes a positive active material.

[0083] The cathode active material is a cathode active material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may be, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, or vanadium oxide, but is not necessarily limited to these; any material used as a cathode active material in the relevant technical field is acceptable. Each cathode active material may be a single material or a mixture of two or more materials.

[0084] Lithium transition metal oxides are, for example, Li a A 1-b B' b D2(wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); 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 equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (In the above equation, 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 O 2-α F' α(In the above equation, 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 equation, 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 O 2-α' F' α (In the above equation, 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 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(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); 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 is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of such a compound may also be used, and a mixture of the compound described above and a compound having a coating layer added may also be used. The coating layer applied to the surface of such a compound comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compound forming this coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0085] The cathode active material may include, for example, a lithium transition metal oxide represented by the following chemical formulas 1 to 8:

[0086] <Chemical Formula 1>

[0087] Li a Ni x Co y M z O 2-b A b

[0088] In the above chemical formula 1,

[0089] 1.0≤a≤1.2, 0≤b≤0.2, 0.8≤x<1, 0≤y≤0.3, 0 <z≤0.3, 및 x+y+z=1이고,

[0090] M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof,

[0091] A is F, S, Cl, Br, or a combination thereof, and

[0092] <Chemical Formula 2>

[0093] LiNi x Co y Mn z O2

[0094] In the above chemical formula 2,

[0095] 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2 및 x+y+z=1이며,

[0096] <Chemical Formula 3>

[0097] LiNi x Co y Al z O2

[0098] In the above chemical formula 3,

[0099] 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2 및 x+y+z=1이며,

[0100] <Chemical Formula 4>

[0101] LiNi x Co y Mn z Al w O2

[0102] In the above chemical formula 4,

[0103] 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2, 0<w≤0.2, 및 x+y+z+w=1이며,

[0104] <Chemical Formula 5>

[0105] Li a Co x M y O 2-b A b

[0106] In the above chemical formula 5,

[0107] 1.0≤a≤1.2, 0≤b≤0.2, 0.9≤x≤1, 0≤y≤0.1, and x+y=1, and

[0108] M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof,

[0109] A is F, S, Cl, Br, or a combination thereof, and

[0110] <Chemical Formula 6>

[0111] Li a Ni x Mn y M' z O 2-b A b

[0112] In the above chemical formula 6,

[0113] 1.0≤a≤1.2, 0≤b≤0.2, 0 <x≤0.3, 0.5≤y<1, 0<z≤0.3, 및 x+y+z=1이고,

[0114] M' is cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and

[0115] A is F, S, Cl, Br, or a combination thereof, and

[0116] <Chemical Formula 7>

[0117] Li a M1 x M2 y PO 4-b X b

[0118] In the above chemical formula 7, 0.90≤a≤1.1, 0≤x≤0.9, 0≤y≤0.5, 0.9 <x+y<1.1, 0≤b≤2 이며,

[0119] M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof, and

[0120] M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y), or a combination thereof, and X is O, F, S, P, or a combination thereof.

[0121] <Chemical Formula 8>

[0122] Li a M3 z PO4

[0123] In the above chemical formula 8, 0.90≤a≤1.1 and 0.9≤z≤1.1, and

[0124] M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

[0125] The oxide-based cathode active material may be covered by a coating layer. The coating layer may be any material known as a coating layer for the cathode active material of an all-solid-state secondary battery. For example, the coating layer is Li2O-ZrO2(LZO), etc.

[0126] The size of the oxide-based cathode active material may be, for example, 0.1 to 30 μm, 0.5 to 20 μm, or 1 to 15 μm. The oxide-based cathode active material may be, for example, single-crystal particles or polycrystalline particles.

[0127] The shape of the positive active material is, for example, a particle shape such as a sphere, an elliptical sphere, etc. The particle size of the positive active material is not particularly limited and is within a range applicable to the positive active material of a conventional all-solid-state secondary battery. The content of the positive active material of the positive (10) is also not particularly limited and is within a range applicable to the positive (10) of a conventional all-solid-state secondary battery. The content of the positive active material included in the positive active material layer (12) may be 80 to 99 weight%, 80 to 95 weight%, or 80 to 90 weight% of the total weight of the positive active material layer (12).

[0128] (Solid electrolyte)

[0129] The positive electrode active material layer (12) may further include, for example, a solid electrolyte. The solid electrolyte may be, for example, a sulfide-based solid electrolyte. The solid electrolyte included in the positive electrode (10) may be the same as or different from the solid electrolyte included in the solid electrolyte layer (30). For details regarding the solid electrolyte, refer to the solid electrolyte layer (30).

[0130] The solid electrolyte included in the positive electrode active material layer (12) may have a smaller D50 average particle size compared to the solid electrolyte included in the solid electrolyte layer (30). For example, the D50 average particle size of the solid electrolyte included in the positive electrode active material layer (12) 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 D50 average particle size of the solid electrolyte included in the solid electrolyte layer (30). The D50 average particle size is, for example, the median particle diameter (D50). The median particle diameter (D50) is the particle size corresponding to 50% of the cumulative volume calculated from the side of the particle having a small particle size in the particle size distribution measured, for example, by laser diffraction. The solid electrolyte content included in the positive electrode active material layer (12) may be, for example, 1 wt% to 40 wt%, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer (12).

[0131] (Challenge)

[0132] The positive electrode active material layer (12) may further include a conductive material. The conductive material may be, for example, a carbon-based conductive material, a metal-based conductive material, or a combination thereof. The carbon-based conductive material may be, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or a combination thereof, but is not limited to these, and any material used as a carbon-based conductive material in the relevant technical field is possible. The metal-based conductive material may be metal powder, metal fiber, or a combination thereof, but is not limited to these, and any material used as a metal-based conductive material in the relevant technical field is possible. The content of the conductive material included in the positive electrode active material layer (12) may be, for example, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer (12).

[0133] (bookbinder)

[0134] The positive active material layer (12) may further include a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these and any binder used in the relevant technical field may be used. The binder content included in the positive active material layer (12) may be, for example, 1 wt% to 10 wt% of the total weight of the positive active material layer (12). The binder may be omitted.

[0135] (Other additives)

[0136] The positive active material layer (12) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, binder, and conductive material described above.

[0137] The filler, coating agent, dispersant, ion-conducting auxiliary agent, etc. that the positive electrode active material layer (12) may include can be any known material generally used in the electrodes of all-solid-state secondary batteries.

[0138] [All-solid-state secondary battery]

[0139] A solid-state secondary battery according to one embodiment comprises the anode described above; a cathode; and a solid electrolyte layer between the anode and the cathode.

[0140] An all-solid-state secondary battery can provide reduced internal resistance and improved cycle characteristics by having a positive electrode having reduced porosity.

[0141] FIG. 4 is a schematic cross-sectional view of an all-solid-state secondary battery (100) according to one embodiment.

[0142] A solid-state secondary battery (100) comprises a positive electrode (10); a negative electrode (20); and a solid electrolyte layer (30). The positive electrode (10) comprises a positive current collector (11) and a positive active material layer (12). The negative electrode (20) comprises a negative current collector (21) and a negative active material (22).

[0143] (anode)

[0144] Refer to the anode described above.

[0145] (cathode)

[0146] Referring to FIG. 4, the cathode (20) includes a cathode current collector (11) and a cathode active material layer (22).

[0147] (Cathode active material layer)

[0148] The ratio (B / A) of the initial charge capacity (B) of the negative active material layer (22) and the initial charge capacity (A) of the positive active material layer (12) may be, for example, 0.001 to 0.45, 0.005 to 0.4, 0.01 to 0.3, 0.01 to 0.2, or 0.01 to 0.1. The initial charge capacity of the positive active material layer (12) is the first open circuit voltage (1 st From open circuit voltage) Li / Li + The initial charging capacity of the negative electrode active material layer (22) is determined by charging up to the maximum charging voltage. nd From open circuit voltage) Li / Li + It is determined by charging up to 0.01 V. The maximum charging voltage is determined by the type of cathode active material. The maximum charging voltage can be, for example, 1.5 V, 2.0 V, 2.5 V, 3.0 V, 3.5 V, 4.0 V, 4.2 V, or 4.3 V. For example, the maximum charging voltage of Li2S or Li2S composites is Li / Li + For this, it can be determined to be between 2.5 and 3.0 V. For example, the maximum charging voltage of a lithium transition metal oxide is Li / Li+ It can be determined between 3.0 and 4.5 V.

[0149] The initial charge capacity (mAh) of the positive active material layer (12) is obtained by multiplying the charge specific capacity (mAh / g) of the positive active material by the mass (g) of the positive active material in the positive active material layer (12). When multiple types of positive active materials are used, the charge specific capacity × mass value is calculated for each positive active material, and the sum of these values ​​is the initial charge capacity of the positive active material layer (12). The initial charge capacity of the negative active material layer (22) is calculated in the same way. The initial charge capacity of the negative active material layer (22) is obtained by multiplying the charge specific capacity (mAh / g) of the negative active material by the mass of the negative active material in the negative active material layer (22). When multiple types of negative active materials are used, the charge specific capacity × mass value is calculated for each negative active material, and the sum of these values ​​is the initial charge capacity of the negative active material layer (22). The charge capacity density of each of the positive active material and the negative active material can be measured using an all-solid-state half-cell using lithium metal as the counter electrode. The initial charge capacity of each of the positive active material layer (12) and the negative active material layer (22) is at a constant current density, e.g., 0.1 mA / cm² 2 This can be directly measured using an all-solid-state half-cell. For the anode, the measurement is taken from the first open-circuit voltage (OCV) to the maximum charging voltage, e.g., 3.0 V (vs. Li / Li). + It can be performed for an operating voltage up to ). For the cathode, the measurement can be performed for an operating voltage from the second open circuit voltage (OCV) down to 0.01 V for the cathode, e.g., lithium metal. For example, an all-solid-state half-electrode having a positive electrode active material layer 0.1 mA / cm² from the first open circuit voltage up to 3.0 V. 2It can be charged with a constant current. The all-solid-state half-paper having the first negative electrode active material layer can be charged at 0.1 mA / cm² from the second open circuit voltage up to 0.01 V. 2 It can be charged with a constant current. The current density during constant current charging is, for example, 0.2 mA / cm² 2 , or 0.5 mA / cm 2 It may be. An all-solid-state half battery having a positive active material layer may be charged, for example, from a first open-circuit voltage to 2.5 V, 2.0 V, 3.5 V, 4.0 V, or 4.5 V. The maximum charging voltage of the positive active material layer may be determined by the maximum voltage of the battery satisfying safety conditions according to JISC8712:2015 of the Japanese Standards Association.

[0150] If the initial charge capacity of the negative electrode active material layer (22) is excessively small, the thickness of the negative electrode active material layer (22) becomes very thin, and thus, during repeated charge and discharge processes, lithium dendrites formed between the negative electrode active material layer (22) and the negative electrode current collector (21) may collapse the negative electrode active material layer (22), making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (100). If the charge capacity of the negative electrode active material layer (22) increases excessively, the energy density of the all-solid-state secondary battery (100) decreases, and the internal resistance of the all-solid-state secondary battery (100) caused by the negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (100).

[0151] The thickness of the negative electrode active material layer (22) is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the positive electrode active material layer (12). The thickness of the negative electrode active material layer (22) is, for example, 1 to 50%, 1 to 40%, 1 to 30%, 1 to 20%, or 1 to 10% of the thickness of the positive electrode active material layer (12). The thickness of the negative electrode active material layer (22) is, for example, 1 to 50 μm, 2 to 40 μm, 3 to 30 μm, 4 to 20 μm, or 5 μm to 20 μm. If the thickness of the negative electrode active material layer (22) is excessively thin, lithium dendrites formed between the negative electrode active material layer (22) and the negative electrode current collector (21) may cause the negative electrode active material layer (22) to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (100). If the thickness of the negative electrode active material layer (22) is excessively increased, the energy density of the all-solid-state secondary battery (100) decreases, and the internal resistance of the all-solid-state secondary battery (100) caused by the negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (100). If the thickness of the negative electrode active material layer (22) decreases, for example, the initial charge capacity of the negative electrode active material layer (22) also decreases.

[0152] (Lithium metal layer)

[0153] Although not shown in the drawing, the all-solid-state secondary battery (100) may further include a lithium metal layer disposed between, for example, a negative electrode current collector (21) and a negative electrode active material layer (22) after charging. The lithium metal layer is a metal layer containing lithium or a lithium alloy. Therefore, since the lithium metal layer is a metal layer containing lithium, it acts as, for example, a lithium reservoir. The lithium alloy is, 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 to these, and any alloy used as a lithium alloy in the relevant technical field is possible. The lithium metal layer may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The lithium metal layer is, for example, a plated layer. The lithium metal layer is, for example, deposited between the negative electrode active material layer (22) and the negative electrode current collector (21) during the charging process of the all-solid-state secondary battery (100).

[0154] The thickness of the lithium metal layer is not particularly limited, but, for example, 1 to 200 μm, 1 to 150 μm, 1 to 100 μm, 1 to 50 μm, 1 to 30 μm, 1 to 22 μm, or 1 μm to 10 μm. If the thickness of the lithium metal layer is excessively thin, it is difficult for the lithium metal layer to perform the role of a lithium reservoir. If the thickness of the lithium metal layer is excessively thick, the mass and volume of the all-solid-state secondary battery (100) increase, and there is a possibility that the cycle characteristics of the all-solid-state secondary battery (100) may deteriorate.

[0155] The thickness of the lithium metal layer may be smaller than, for example, the thickness of the negative electrode active material layer (22). The thickness of the lithium metal layer may be, for example, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less of the thickness of the negative electrode active material layer (22). The thickness of the lithium metal layer may be, for example, 1 to 70%, 1 to 60%, 1 to 50%, 1 to 40%, or 1 to 30% of the thickness of the negative electrode active material layer (22). As the thickness of the lithium metal layer becomes smaller than the thickness of the negative electrode active material layer (22), volume change during charging and discharging of the all-solid-state secondary battery can be suppressed. Consequently, degradation due to volume change of the all-solid-state secondary battery can be suppressed.

[0156] Alternatively, in the all-solid-state secondary battery (100), a lithium metal layer may be placed between the negative electrode current collector (21) and the negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (100), for example. When a lithium metal layer is placed between the negative electrode current collector (21) and the negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (100), the lithium metal layer acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between the negative electrode current collector (21) and the negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (100).

[0157] When a lithium metal layer is precipitated by charging after assembly of the all-solid-state secondary battery (100), the energy density of the all-solid-state secondary battery (100) increases because the lithium metal layer is not included during assembly of the all-solid-state secondary battery (100). When charging the all-solid-state secondary battery (100), the charging capacity of the negative electrode active material layer (22) is exceeded. That is, the negative electrode active material layer (22) is overcharged. At the beginning of charging, lithium is absorbed in the negative electrode active material layer (22). The negative electrode active material contained in the negative electrode active material layer (22) forms an alloy or compound with lithium ions that have moved from the positive electrode (10). When charging exceeds the capacity of the negative electrode active material layer (22), lithium is precipitated, for example, on the back surface of the negative electrode active material layer (22), that is, between the negative electrode current collector (21) and the negative electrode active material layer (22), and a metal layer corresponding to the lithium metal layer is formed by the precipitated lithium. The lithium metal layer is a metal layer composed mainly of lithium (i.e., metallic lithium). This result is obtained, for example, by the negative active material included in the negative active material layer (22) containing a material that forms an alloy or compound with lithium. During discharge, the lithium in the negative active material layer (22) and the lithium metal layer, i.e., the metal layer, is ionized and moves toward the positive electrode (10). Therefore, it is possible to use lithium as the negative active material in the all-solid-state secondary battery (100). In addition, since the negative active material layer (22) covers the lithium metal layer, it acts as a protective layer for the lithium metal layer, i.e., the metal layer, while simultaneously suppressing the precipitation growth of lithium dendrites. Therefore, it suppresses short circuits and capacity degradation of the all-solid-state secondary battery (100), and consequently improves the cycle characteristics of the all-solid-state secondary battery (100). Additionally, when a lithium metal layer is disposed by charging after assembly of the all-solid-state secondary battery (100), the negative electrode (20), that is, the negative electrode current collector (21) and the negative electrode active material layer (22) and the region between them are Li-free regions that do not contain lithium (Li) in the initial state or after complete discharge of the all-solid-state secondary battery (100).

[0158] (Cathode active material)

[0159] The negative electrode active material layer (22) includes a negative electrode active material.

[0160] The negative electrode active material may have a particle form, for example. The particle size of the negative electrode active material is, for example, less than 1 μm, 500 nm or less, 300 nm or less, or 100 nm or less. The particle size of the negative electrode active material is, for example, 10 nm to less than 1 μm, 10 nm to 900 nm, 10 to 700 nm, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm. By having a particle size within this range, the negative electrode active material can more easily perform reversible absorption and / or desorption of lithium during charging and discharging. The particle size of the negative electrode active material is, for example, the average particle size of the negative electrode active material. The average particle size of the cathode active material may be, for example, the median diameter (D50) measured using a laser particle size distribution meter. Alternatively, the particle size of the cathode active material may be measured, for example, using a scanning electron microscope.

[0161] The aspect ratio of the negative electrode active material is, for example, 5 or less, 4 or less, 3 or less, or 2 or less. The aspect ratio of the negative electrode active material is, for example, 1 to 5, 1 to 4, 1 to 3, or 1 to 2. By having an aspect ratio within this range, the negative electrode active material can be distributed more uniformly within the negative electrode active material layer (22). Non-uniformity of volume change during charging and discharging of the negative electrode active material can be suppressed. The aspect ratio of the negative electrode active material can be measured, for example, by a scanning electron microscope. By having an aspect ratio within this range, the high-rate characteristics of the all-solid-state secondary battery containing the negative electrode active material can be further improved.

[0162] The cathode active material includes a metal-based cathode active material, a carbon-based cathode active material, or a combination thereof.

[0163] Metal-based negative electrode active materials may include, for example, a metal capable of forming an alloy with lithium or a metal capable of forming a compound with lithium. Metal-based negative electrode active materials may include, for example, zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. For example, nickel (Ni) does not form an alloy with lithium and therefore is not included in the metal-based negative electrode active materials of this specification.

[0164] Carbon-based cathode active materials include, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof. The carbon-based cathode active material is, for example, amorphous carbon. Amorphous carbon may include, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, or a combination thereof. Amorphous carbon is carbon that does not possess crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon. The degree of grystalllinity of the carbon-based cathode active material is, for example, the intensity of the peak attributed to crystalline carbon in the XRD spectrum of the carbon-based material (I crystalline ) and the intensity of the peak attributed to amorphous carbon (I amorphousIt can be calculated from the percentage of ). If the above percentage value is low, it is carbon with low crystallinity. The carbon-based cathode active material may be, for example, porous carbon. The pore volume contained in the porous carbon is, for example, 0.1 cc / g to 10.0 cc / g, 0.5 cc / g to 5 cc / g, or 0.1 cc / g to 1 cc / g. The average pore diameter contained in the porous carbon is, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. The BET specific surface area of ​​the porous carbon is, for example, 100 m² 2 / g to 3000 m 2 / g. The average pore size and BET specific surface area of ​​porous carbon can be measured, for example, by the nitrogen gas adsorption method.

[0165] The negative electrode active material layer (22) may include a type of second negative electrode active material among these negative electrode active materials, or may include a mixture of multiple different negative electrode active materials. The negative electrode active material layer (22) may include, for example, only amorphous carbon. Alternatively, the negative electrode active material layer (22) may include zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. Alternatively, the negative electrode active material layer (22) comprises a mixture of amorphous carbon and zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. The mixing ratio of the mixture of a carbon-based negative electrode active material, such as amorphous carbon, and a metal-based negative electrode active material, such as zinc, may be, for example, 99:1 to 1:99, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight. By having the negative electrode active material with such a composition, the high-rate characteristics of the all-solid-state secondary battery (100) can be further improved.

[0166] The negative electrode active material layer (22) comprises a negative electrode active material, and the negative electrode active material may comprise a mixture of a first particle made of, for example, amorphous carbon and a second particle made of a metal-based negative electrode active material. The metal-based negative electrode active material comprises, for example, gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The content of the second particle is 1 to 60 weight%, 8 to 60 weight%, 10 to 50 weight%, 15 to 40 weight%, or 20 to 30 weight% based on the total weight of the mixture of the first particle and the second particle. By having the second particle in this range, the cycle characteristics of the all-solid-state secondary battery (100) can be further improved.

[0167] (bookbinder)

[0168] The negative electrode active material layer (22) may further include a binder.

[0169] The binder is, for example, a polymer binder. The polymer binder included in the negative electrode active material layer (22) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any binder used in the relevant technical field is possible. The binder may be composed of a single binder or a plurality of different binders. The polymer binder may include, for example, a fluorine-based binder.

[0170] The negative active material layer (22) is stabilized on the negative current collector (21) by further including a binder. Additionally, cracking of the negative active material layer (22) is suppressed despite changes in volume and / or relative position of the negative active material layer (22) during the charging and discharging process. For example, if the negative active material layer (22) does not include a binder, it is possible for the negative active material layer (22) to be easily separated from the negative current collector (21). As the negative active material layer (22) is separated from the negative current collector (21), the possibility of a short circuit occurring increases as the negative current collector (21) comes into contact with the solid electrolyte layer (30) in the exposed portion of the negative current collector (21). The negative active material layer (22) is manufactured, for example, by applying a slurry in which the material constituting the negative active material layer (22) is dispersed onto the negative current collector (21) and drying it. By including a binder in the negative electrode active material layer (22), stable dispersion of the negative electrode active material and the fibrous carbon-based material in the slurry is possible. For example, when the slurry is applied onto the negative electrode current collector (21) by a screen printing method, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the negative electrode active material).

[0171] The binder content may be 0.1 to 20 parts by weight, 0.1 to 15 parts by weight, 1 to 10 parts by weight, or 5 to 10 parts by weight per 100 parts by weight of the negative electrode active material. By having a binder content within this range, the high-rate characteristics of the all-solid-state secondary battery (100) can be further improved.

[0172] (Other additives)

[0173] The negative electrode active material layer (22) may further include additives used in the all-solid-state secondary battery (100), such as fillers, coating agents, dispersants, ion-conducting aids, etc.

[0174] (Cathode current collector)

[0175] The negative electrode current collector (21) is composed of a material that does not react with, for example, lithium, that is, does not form any alloys or compounds. The material constituting the negative electrode current collector (21) may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector (21) may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector (21) is, for example, in the form of a plate or foil.

[0176] Although not shown in the drawing, the all-solid-state secondary battery (100) may further include a thin film containing an element capable of forming an alloy with lithium on one surface of the negative electrode current collector (21). The thin film is disposed between the negative electrode current collector (21) and the negative electrode active material layer (22). The thin film contains, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium is, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not necessarily limited to these, and any element capable of forming an alloy with lithium in the relevant technical field is possible. The thin film is composed of one of these metals or is composed of an alloy of various types of metals. By placing the thin film on one side of the negative electrode current collector (21), the deposition pattern of the lithium metal layer (23) deposited between, for example, the thin film and the negative electrode active material layer (22) is further flattened, and the cycle characteristics of the all-solid-state secondary battery (100) can be further improved. The thickness of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is less than 1 nm, it may be difficult to perform the function of the thin film. If the thickness of the thin film is excessively thick, the thin film itself absorbs lithium, and the amount of lithium deposited at the negative electrode decreases, which lowers the energy density of the all-solid-state battery and may lower the cycle characteristics of the all-solid-state secondary battery (100). The thin film can be placed on the negative current collector (21) by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods, and any method capable of forming a thin film in the relevant technical field is possible.

[0177] Although not shown in the drawing, the negative current collector (21) may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon the occurrence of a short circuit, thereby blocking battery operation and suppressing a sudden increase in current. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative current collector (21) may additionally include a metal piece and / or a lead tab. For more specific details regarding the base film, metal layer, metal chip, and lead tab of the negative electrode current collector (21), refer to the positive electrode current collector (11) described above. By having this structure, the negative electrode current collector (21) can reduce the weight of the negative electrode and, consequently, improve the energy density of the negative electrode and the lithium battery.

[0178] (Solid electrolyte layer)

[0179] Referring to FIG. 4, the all-solid-state secondary battery (100) includes a solid electrolyte layer (30).

[0180] The solid electrolyte layer (30) may have, for example, a single-layer structure or a multi-layer structure. The solid electrolyte layer (30) may have, for example, a 2 to 100-layer, 2 to 10, or 2 to 4-layer structure.

[0181] The solid electrolyte layer (30) includes a first solid electrolyte layer (30a) disposed adjacent to the positive electrode and a second solid electrolyte layer (30b) disposed adjacent to the negative electrode. The first solid electrolyte layer and the second solid electrolyte layer may be distinguished by one or more physical properties such as composition, density, and porosity. Alternatively, the first solid electrolyte layer (30a) and the second solid electrolyte layer (30b) may not be distinguished by one or more physical properties such as composition, density, and porosity, but may be manufactured separately and stacked during the manufacturing process of the all-solid-state secondary battery (100) to form the solid electrolyte layer.

[0182] The porosity (P1) of the first solid electrolyte layer can be distinguished from, for example, the porosity (P2) of the second solid electrolyte layer. The porosity (P1) of the first solid electrolyte layer may be lower than, for example, the porosity (P2) of the second solid electrolyte layer. The ratio (P1 / P2) of the porosity (P1) of the first solid electrolyte layer and the porosity (P2) of the second solid electrolyte layer may be less than 1, 0.99 or less, 0.95 or less, or 0.9 or less. For example, the first solid electrolyte layer may be prepared by pressurizing it to a higher pressure than the second solid electrolyte layer.

[0183] Alternatively, the porosity (P1) of the first solid electrolyte layer may be higher than, for example, the porosity (P2) of the second solid electrolyte layer. The ratio (P1 / P2) of the porosity (P1) of the first solid electrolyte layer and the porosity (P2) of the second solid electrolyte layer may be greater than 1, greater than 1.01, greater than 1.05, or greater than 1.1. For example, the first solid electrolyte layer may be prepared by pressurizing it to a lower pressure than the second solid electrolyte layer.

[0184] The porosity (P1) of the first solid electrolyte layer and the porosity (P2) of the second solid electrolyte layer are each the ratio of the area of ​​the pores to the total area of ​​the solid electrolyte layer measured from a scanning electron microscope image of the cross-section of the secondary battery.

[0185] (Solid electrolyte)

[0186] The solid electrolyte layer (30) contains a solid electrolyte.

[0187] Solid electrolytes may include, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0188] Solid electrolytes are, for example, sulfide-based solid electrolytes. Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, 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 positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, 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, 0(x(2) is one or more selected from. Sulfide-based solid electrolytes are 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. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the mixed molar ratio of Li2S and P2S5 is, for example, Li2S : P2S5 = 20 : 80 to 90 : 10, 25 : 75 to 90 : 10, 30 : The range is approximately 70 to 70:30, 40:60 to 60:40.

[0189] Sulfide-based solid electrolytes may include, for example, an argyrodite-type solid electrolyte represented by the following chemical formula A:

[0190] <Chemical Formula A>

[0191] Li + 12-n-x A n+ X 2- 6-x Y - x

[0192] In the above formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; X is S, Se, or Te; Y is Cl, Br, I, F, CN, OCN, SCN, or N3; and 1(n(5) and 0(x(2). Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-xPS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x It may be an argyrodite-type compound containing one or more selected from 0≤x≤2. The sulfide-based solid electrolyte may be an argyrodite-type compound containing, for example, one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0193] The density of the argyrodite-type solid electrolyte may be 1.5 to 2.0 g / cc. Since the argyrodite-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 layer by Li can be effectively suppressed.

[0194] Oxide-based solid electrolytes are, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, 0≤x≤10), or a combination thereof. Oxide-based solid electrolytes are produced, for example, by sintering.

[0195] Oxide-based solid electrolytes are, for example, Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M-doped LLZO, M=Ga, W, Nb, Ta, or Al, 0 <a<2, 0≤x≤10) 중에서 선택된 가넷계(Garnet-type) 고체전해질이다.

[0196] The polymer solid electrolyte may, for example, comprise a mixture of a lithium salt and a polymer, or comprise a polymer having ion-conducting functional groups. The polymer solid electrolyte may, for example, be a polymer electrolyte that is in a solid state at 25 °C and 1 atm. The polymer solid electrolyte may, for example, not contain a liquid.The polymeric solid electrolyte comprises a polymer, wherein the polymer is, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN). Polyaniline, Polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, Sulfonated poly(ether ether ketone) (SPEEK), Sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), Sulfonated poly(aryl ether ketone) (SPAEK), Poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), Poly(styrene sulfonate) (PSS), Lithium 9,10-Diphenylanthracene-2-sulfonate (lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi. +It may be ) or a combination thereof, but is not limited thereto, and any that are used in polymer electrolytes in the relevant technical field are permitted. Any lithium salt that can be used as a lithium salt in the relevant technical field is permitted. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 The polymer may be SO2)(x and y are each 1 to 20), LiCl, LiI, or a mixture thereof. The polymer included in the polymer solid electrolyte may be, for example, a compound containing 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight-average molecular weight of the polymer included in the polymer solid electrolyte may be, for example, 1,000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0197] Gel electrolytes are, for example, polymeric gel electrolytes. Gel electrolytes can have a gel state without, for example, containing polymers.

[0198] The polymer gel electrolyte may, for example, comprise a liquid electrolyte and a polymer, or comprise an organic solvent and a polymer having ion-conducting functional groups. The polymer gel electrolyte may, for example, be a polymer electrolyte in a gel state at 25 °C and 1 atm. The polymer gel electrolyte may, for example, have a gel state without containing a liquid. The liquid electrolyte used in the polymer gel electrolyte may, for example, be an ionic liquid, a mixture of a lithium salt and an organic solvent; a mixture of a lithium salt and an organic solvent; a mixture of an ionic liquid and an organic solvent; or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer used in the polymer gel electrolyte may be selected from the polymers used in solid polymer electrolytes. The organic solvent may be selected from the organic solvents used in liquid electrolytes. Organic solvents are, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof. The lithium salt may be selected from lithium salts used in polymer solid electrolytes. Ionic liquids refer to salts or room-temperature molten salts that have a melting point below room temperature, are composed solely of ions, and exist in a liquid state at room temperature. Ionic liquids are, for example, a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, 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 include one or more compounds selected from those containing one or more anions selected from among. The polymer solid electrolyte may form a polymer gel electrolyte by impregnating it into a liquid electrolyte in a secondary battery, for example. The polymer gel electrolyte may further include inorganic particles. The polymer included in the polymer gel electrolyte may be a compound containing, for example, 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight-average molecular weight of the polymer included in the polymer gel electrolyte may be, for example, 500 Dalton or more, 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0199] (bookbinder)

[0200] The solid electrolyte layer (30) may further include a binder. The binder included in the solid electrolyte layer (30) is, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these and any binder used in the relevant technical field is possible. The binder of the solid electrolyte layer (30) may be selected from the binders used in the positive electrode active material layer (12) and the negative electrode active material layer (22). The binder may be omitted. The binder content of the solid electrolyte layer (30) is, for example, 0.1 to 10 wt% with respect to the total weight of the solid electrolyte layer (30).

[0201] [Method for manufacturing all-solid-state secondary batteries]

[0202] A method for manufacturing an all-solid-state secondary battery according to another embodiment comprises the steps of: preparing an anode-solid electrolyte layer laminate by first pressing the anode and the solid electrolyte layer together with a first pressurizing auxiliary layer; and preparing an all-solid-state secondary battery by second pressing the anode-solid electrolyte layer laminate and the cathode-solid electrolyte layer laminate together with a second pressurizing auxiliary layer. By pressing the anode together with the first pressurizing auxiliary layer, an anode including an anode active material layer having reduced porosity and improved ion conductivity can be manufactured. By pressing the anode, the solid electrolyte layer, and the cathode together with the second pressurizing auxiliary layer, an all-solid-state secondary battery providing reduced porosity, reduced internal resistance, and improved cycle characteristics can be manufactured.

[0203] FIG. 5a is a schematic cross-sectional view of a positive electrode used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5b is a schematic cross-sectional view of a solid electrolyte layer / protection layer laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5c is a schematic cross-sectional view of a first pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 5d is a schematic cross-sectional view of a positive electrode-solid electrolyte laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment.

[0204] First, an anode (10) and a solid electrolyte layer are first pressurized together with a first pressurizing auxiliary layer to prepare an anode-solid electrolyte layer laminate.

[0205] Referring to FIG. 5a, a positive electrode (10) is prepared. A positive electrode active material slurry is prepared by mixing a positive electrode active material, a solid electrolyte, a binder, a conductive material, and a solvent. The positive electrode is prepared by coating and drying the positive electrode active material slurry on one side of a positive electrode current collector (11). Alternatively, a positive electrode (10) may be prepared by casting a positive electrode active material composition onto a separate support and then peeling off the film obtained from this support and laminating it onto a positive electrode current collector (11).

[0206] Referring to FIG. 5b, a solid electrolyte layer (30, 30a) / protective layer (40) laminate is prepared. A solid electrolyte slurry is prepared by mixing a solid electrolyte, a binder, and a solvent. The solid electrolyte slurry is coated and dried on one side of a substrate to prepare a solid electrolyte layer (30, 30b). Alternatively, a solid electrolyte composition may be cast onto a separate support and then peeled off from the support to obtain a film-shaped solid electrolyte layer (30, 30a). For pressurization, the solid electrolyte layer (30, 30a) is placed on the protective layer (40) to prepare a solid electrolyte layer (30, 30a) / protective layer (40) laminate. The protective layer (40) is a metal sheet having a thickness of, for example, 1 mm or more. The metal sheet is, for example, an aluminum sheet or a stainless steel sheet. The protective layer (40) can prevent cracks, etc., in the solid electrolyte layer (30, 30a) when pressurized.

[0207] Referring to FIG. 5c, a stack of a positive electrode (30) and a solid electrolyte layer (30, 30a) / protective layer (40) is pressurized using a first pressurizing auxiliary layer (50, 50a). A stack of a solid electrolyte layer (30, 30a) / protective layer (40) is placed on the positive electrode active material layer (12) of the positive electrode (10), and a first pressurizing auxiliary layer (50a, 50aa, 50ab) is placed on each of the two sides thereof. The positive electrode (10) comprises a positive electrode current collector (11) and a positive electrode active material layer (12) on one side of the positive electrode current collector (11), and the first pressurizing auxiliary layer (50a, 50aa) is placed on the other side of the positive electrode current collector (11). A solid electrolyte layer (30, 30a) / protection layer (40) laminate comprises a protection layer (40) and a solid electrolyte layer (30, 30a) on one side of the protection layer (40), and a first pressurizing auxiliary layer (50a, 50ab) is disposed on the other side of the protection layer (40). By first pressurizing, a first pressurizing auxiliary layer (50aa) / anode current collector (11) / anode active material layer (12) / solid electrolyte layer (30a) / protection layer (40) / first pressurizing auxiliary layer (50ab) laminate is prepared. The first pressurizing can be performed, for example, by a roller (60, 60a, 60b).

[0208] Referring to FIG. 5d, after the first pressurization, the protective layer (40) and the first pressurization auxiliary layer (50aa, 50ab) are removed to prepare an anode-solid electrolyte laminate with an anode current collector (11) / anode active material layer (12) / solid electrolyte layer (30a) structure.

[0209] FIG. 6a is a schematic cross-sectional view of a negative electrode used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6b is a schematic cross-sectional view of a solid electrolyte layer / protection layer laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6c is a schematic cross-sectional view of a first pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 6d is a schematic cross-sectional view of a negative electrode-solid electrolyte laminate used in a method for manufacturing an all-solid-state secondary battery according to one embodiment.

[0210] Next, the cathode (20) and the solid electrolyte layer (30, 30b) are first pressed together with the first pressurizing auxiliary layer (50a, 50aa, 50ab) to prepare a cathode-solid electrolyte laminate.

[0211] Referring to FIG. 6a, a cathode (20) is prepared. A cathode active material slurry is prepared by mixing a cathode active material, a binder, and a solvent. The cathode active material slurry is coated and dried on one side of a cathode current collector (21) to prepare the cathode (20). Alternatively, a cathode active material composition may be cast onto a separate support, and then a film obtained by peeling off from this support is laminated onto the cathode current collector (21) to prepare the cathode (20).

[0212] Referring to FIG. 6b, a solid electrolyte layer (30, 30b) / protection layer (40) laminate is prepared. A solid electrolyte layer (30, 30b) / protection layer (40) laminate is prepared in the same way as in an anode-solid electrolyte laminate. Referring to FIG. 6c, a cathode (20) and a solid electrolyte layer (30, 30b) / protection layer (40) laminate are pressurized using a first pressurizing auxiliary layer (50a, 50aa, 50ab). A solid electrolyte layer (30, 30b) / protection layer (40) laminate is placed on the cathode active material layer (22) of the cathode (20), and a first pressurizing auxiliary layer (50a, 50aa, 50ab) is placed on each of the two sides thereof. The cathode (20) comprises a cathode current collector (21) and a cathode active material layer (22) on one side of the cathode current collector (21), and a first pressurizing auxiliary layer (50a, 50aa) is disposed on the other side of the cathode current collector (21). The solid electrolyte layer (30, 30b) / protection layer (40) laminate comprises a protection layer (40) and a solid electrolyte layer (30, 30b) on one side of the protection layer (40), and a first pressurizing auxiliary layer (50a, 50ab) is disposed on the other side of the protection layer (40). By first pressurization, a first pressurizing auxiliary layer (50aa) / cathode current collector (21) / cathode active material layer (22) / solid electrolyte layer (30b) / protection layer (40) / first pressurizing auxiliary layer (50ab) laminate is prepared. The first pressurization can be performed, for example, by rollers (60, 60a, 60b).

[0213] Referring to FIG. 6d, after the first pressurization, the protective layer (40) and the first pressurization auxiliary layer (50aa, 50ab) are removed to prepare a cathode-solid electrolyte laminate with a structure of a cathode current collector (21) / cathode active material layer (22) / solid electrolyte layer (30b).

[0214] FIG. 7a is a schematic cross-sectional view of a second pressurization process used in a method for manufacturing an all-solid-state secondary battery according to one embodiment. FIG. 7b is a schematic cross-sectional view of an all-solid-state secondary battery manufactured by a method according to one embodiment.

[0215] Next, the positive-solid electrolyte layer laminate and the negative-solid electrolyte layer laminate are pressurized a second time together with the second pressurizing auxiliary layer (50b, 50ba, 50bb) to prepare an all-solid secondary battery (100).

[0216] Referring to FIG. 7a, the positive-solid electrolyte layer laminate and the negative-solid electrolyte layer laminate are pressurized using a second pressurizing auxiliary layer (50ba, 50bb). The negative-solid electrolyte layer laminate is placed on the solid electrolyte layer (30a) of the positive-solid electrolyte layer laminate, and the second pressurizing auxiliary layer (50b, 50ba, 50bb) is placed on both sides thereof. The positive-solid electrolyte layer laminate comprises a positive current collector (11), a positive active material layer (12) on one side of the positive current collector (11), and a solid electrolyte layer (30, 30a) on the positive active material layer (12), and the second pressurizing auxiliary layer (50ba) is placed on the other side of the positive current collector (11). A cathode-solid electrolyte layer laminate comprises a cathode current collector (21), a cathode active material layer (22) on one side of the cathode current collector (21), and a solid electrolyte layer (30, 30b) on the cathode active material layer (22), and a second pressurizing auxiliary layer (50bb) is disposed on the other side of the cathode current collector (21). By the second pressurization, a laminate of the second pressurizing auxiliary layer (50ba) / anode current collector (11) / anode active material layer (12) / solid electrolyte layer (30a) / solid electrolyte layer (30b) / cathode active material layer (22) / cathode current collector (21) / second pressurizing auxiliary layer (50bb) is prepared. The second pressurization can be performed, for example, by a roller (60, 60a, 60b).

[0217] Referring to FIG. 7b, after the second pressurization, the second pressurization auxiliary layer (50ba, 50bb) is removed to manufacture an all-solid-state secondary battery (100) having the structure of a positive current collector (11) / positive active material layer (12) / solid electrolyte layer (30a) / solid electrolyte layer (30b) / negative active material layer (22) / negative current collector (21).

[0218] The first pressurizing auxiliary layer (50a) and the second pressurizing auxiliary layer (50b) may include, for example, a polymer, a metal, wood, or a combination thereof.

[0219] The polymer may include, for example, polyimide (PI), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), polyvinyl chloride (PVC), polyvinyl alcohol, polyacrylate, polyethylene, polypropylene, polystyrene, polyacisobutylene, polyvinyl chloride, vinyl acetate resin, polytetrafluoroethylene, polyacrylonitrile, polymethyl ketacylate, Tetron, nylon, bakelite, urea resin, polysiloxane, or a combination thereof. The metal may include, for example, metals belonging to groups 2 through 16 of the periodic table. The metal may include, for example, aluminum, copper, SUS, zinc, tin, lead, magnesium, titanium, nickel, or a combination thereof. The pressurizing layer may be, for example, a polymer film. The pressurizing layer may be, for example, a multilayer film comprising a polymer layer and a metal layer. The pressurized auxiliary layer may have, for example, a polymer layer structure, a polymer layer / metal layer structure, a polymer layer / metal layer / polymer layer structure, etc.

[0220] The thickness of the first pressurized auxiliary layer (T50a) and / or the second pressurized auxiliary layer (T50b) may be greater than, for example, the thickness of the positive current collector (T11). The ratio of the thickness of the first pressurized auxiliary layer (T50a) and / or the second pressurized auxiliary layer (T50b) to the thickness of the positive current collector (T11) (T50a / T11 and / or T50b / T11) may each be, for example, greater than 1, 0.1 or more, 0.5 or more, or 2 or more. The ratio of the thickness of the first pressurized auxiliary layer (T50a) and / or the second pressurized auxiliary layer (T50b) to the thickness of the positive current collector (T11) (T50a / T11 and / or T50b / T11) may each be, for example, greater than 1 to 100, 0.1 to 50, 0.5 to 20, or 2 to 10. As the thickness of the first pressurized auxiliary layer (T50a) and / or the second pressurized auxiliary layer (T50b) is larger than the thickness of the positive current collector (T11), the porosity of the positive active material layer can be reduced and the internal resistance of the positive active material layer can be reduced.

[0221] The thickness of the first pressurizing auxiliary layer (T50a) and / or the second pressurizing auxiliary layer (T50b) may be, for example, 1 mm or less, 900 μm or less, 500 μm or less, or 300 μm or less. The thickness of the first pressurizing auxiliary layer (T50a) and / or the second pressurizing auxiliary layer (T50b) may be, for example, 20 μm to 1 mm, 20 μm to 900 μm, 20 μm to 500 μm, 20 μm to 300 μm, or 20 μm to 100 μm. By having the first and second pressurizing auxiliary layers have thicknesses within these ranges, more uniform pressure can be delivered to the anode layer. As uniform pressure is delivered to the anode layer, the internal resistance of the anode layer can be further reduced and the porosity of the anode layer can be further reduced. The cycle characteristics of the all-solid-state secondary battery can be improved.

[0222] The first and second pressurizations can be performed by a roll press, a plate press, a warm isostatic press (WIP), a cold isostatic press (CIP), or a hot isostatic press (HIP), respectively. A roll press or a plate press may be used for ease of mass production. A warm isostatic press (WIP), a cold isostatic press (CIP), or a hot isostatic press (HIP) may be used to obtain a lower porosity.

[0223] The first pressure (PR1) may be greater than the second pressure (PR2). The ratio (PR1 / PR2) of the first pressure (PR1) and the second pressure (PR2) may be 2 or more, 5 or more, 10 or more, or 20 or more. The ratio (PR1 / PR2) of the first pressure (PR1) and the second pressure (PR2) may be 2 to 100, 5 to 100, 10 to 100, or 20 to 100. As the ratio (PR1 / PR2) of the first pressure (PR1) and the second pressure (PR2) has this range, uniform pressure is delivered to the anode layer, thereby further reducing the internal resistance of the anode layer and further reducing the porosity of the anode layer. The cycle characteristics of the all-solid-state secondary battery may be improved.

[0224] The present invention is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0225] (Manufacturing of all-solid-state secondary batteries)

[0226] Example 1

[0227] (Preparation of pre-anode-solid electrolyte laminate)

[0228] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Mn0.05 O2 (NCM) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. As a solid electrolyte, Li6PS5Cl, an argyrodite-type crystal (average particle size (D50) = 0.5 μm, crystalline), was prepared. As a binder, a polytetrafluoroethylene (PTFE) binder was prepared. As a conductive agent, carbon nanotubes (CNT) were prepared. A slurry was prepared by mixing these materials with an octyl acetate solvent in a weight ratio of cathode active material: solid electrolyte: conductive agent: binder = 85:10:3:2. The slurry was coated onto one side of an aluminum foil cathode current collector with a thickness of 10 μm, and then a preliminary cathode was prepared by drying at atmospheric pressure at 70°C for 2 hours and then vacuum drying at 70°C for 7 hours.

[0229] A mixture was prepared by adding 1 part by weight of styrene-butadiene rubber (SBR) binder to 100 parts by weight of a crystalline Li6PS5Cl solid electrolyte with an average particle size (D50) of 3 μm. A slurry was prepared by stirring while adding octyl acetate to the prepared mixture. The prepared slurry was applied onto a release film using a blade coater and dried in air at a temperature of 40°C to obtain a laminate. The obtained laminate was vacuum dried at 40°C for 12 hours to prepare a solid electrolyte layer. A preliminary solid electrolyte layer was prepared by placing the solid electrolyte layer on one side of an aluminum sheet and removing the release film.

[0230] A preliminary solid electrolyte layer was placed on the preliminary anode, and a polyimide (PI) film pressurizing layer with a thickness of 20 μm was placed on the upper and lower surfaces of the preliminary anode, respectively, and a roll press was performed at a pressure of 3 t / cm.

[0231] After roll pressing, the aluminum sheet and the pressure auxiliary layer were removed to prepare a preliminary anode-solid electrolyte laminate.

[0232] (Preparation of pre-cathode-solid electrolyte laminate)

[0233] A nickel (Ni) foil with a thickness of 10 μm was prepared as a negative electrode current collector. As a negative electrode active material, a mixture of carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle diameter of about 60 nm in a 3:1 weight ratio was prepared. 4 g of the prepared mixture was placed in a container, and 4 g of an NMP solution containing 7 wt% of PVDF binder (Kureha # 9300) was added to prepare a mixed solution. Subsequently, a slurry was prepared by stirring the mixed solution while adding NMP little by little to this mixed solution. The prepared slurry was applied onto the carbon layer of the prepared negative electrode current collector using a bar coater, dried at atmospheric pressure in air at 70 °C for 2 hours, and then vacuum dried at 70 °C for 7 hours to prepare a preliminary negative electrode.

[0234] A preliminary solid electrolyte layer was prepared in the same manner as in the fabrication of the preliminary anode-solid electrolyte laminate.

[0235] A preliminary solid electrolyte layer was placed on the preliminary cathode, and a polyimide (PI) film pressurizing layer with a thickness of 20 μm was placed on the upper and lower surfaces of the same, respectively, and a roll press was performed at a pressure of 2.5 t / cm.

[0236] After roll pressing, the aluminum sheet and the pressure auxiliary layer were removed to prepare a preliminary cathode-solid electrolyte laminate.

[0237] (All-solid-state secondary battery manufacturing)

[0238] A pre-negative-solid electrolyte laminate was placed such that the solid electrolyte layer of a pre-negative-solid electrolyte laminate faced the solid electrolyte layer of a pre-negative-solid electrolyte laminate, and a polyimide (PI) film pressure-assist layer with a thickness of 20 μm was placed on the upper and lower surfaces of the pre-negative-solid electrolyte laminate, respectively, and a roll press was performed at a pressure of 0.1 t / cm to manufacture an all-solid-state secondary battery. After the roll press, the pressure-assist layer was removed.

[0239] Examples 2 to 5

[0240] An all-solid-state secondary battery was manufactured using the same method as in Example 1, except that the thickness of the pressurized auxiliary layer was changed. Refer to Table 1 for the pressurized auxiliary layer.

[0241] Example 6

[0242] (Preliminary anode manufacturing)

[0243] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Mn 0.05 O2 (NCM) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. As a solid electrolyte, Li6PS5Cl, an argyrodite-type crystal (average particle size (D50) = 0.5 μm, crystalline), was prepared. As a binder, a polytetrafluoroethylene (PTFE) binder was prepared. As a conductive agent, carbon nanotubes (CNT) were prepared. A slurry was prepared by mixing these materials with an octyl acetate solvent in a weight ratio of cathode active material: solid electrolyte: conductive agent: binder = 85:10:3:2. This slurry was coated onto one side of an aluminum foil cathode current collector with a thickness of 10 μm, and then a preliminary cathode was prepared by drying at atmospheric pressure at 70°C for 2 hours and then vacuum drying at 70°C for 7 hours.

[0244] (Preparation of preliminary solid electrolyte layer)

[0245] A mixture was prepared by adding 1 part by weight of styrene-butadiene rubber (SBR) binder to 100 parts by weight of a crystalline Li6PS5Cl solid electrolyte with an average particle size (D50) of 3 μm. A slurry was prepared by stirring while adding octyl acetate to the prepared mixture. The prepared slurry was applied onto a release film using a blade coater and dried in air at a temperature of 40°C to obtain a laminate. The obtained laminate was vacuum dried at 40°C for 12 hours to prepare a pre-solid electrolyte layer. In the all-solid-state battery manufacturing step, the pre-solid electrolyte layer was placed on the pre-negative electrode laminate, and then the release film was removed.

[0246] (Preparation of pre-cathode)

[0247] A nickel (Ni) foil with a thickness of 10 μm was prepared as a negative electrode current collector. As a negative electrode active material, a mixture of carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle diameter of about 60 nm in a 3:1 weight ratio was prepared. 4 g of the prepared mixture was placed in a container, and 4 g of an NMP solution containing 7 wt% of PVDF binder (Kureha # 9300) was added to prepare a mixed solution. Subsequently, a slurry was prepared by stirring the mixed solution while adding NMP little by little to this mixed solution. The prepared slurry was applied onto the carbon layer of the prepared negative electrode current collector using a bar coater, dried at atmospheric pressure in air at 70 °C for 2 hours, and then vacuum dried at 70 °C for 7 hours to prepare a preliminary negative electrode.

[0248] (All-solid-state secondary battery manufacturing)

[0249] A preliminary electrode assembly was prepared by stacking a preliminary cathode, a preliminary solid electrolyte layer, and a preliminary anode in this order. In the preliminary electrode assembly, the cathode active material layer of the cathode and the anode active material layer of the anode were arranged to contact the solid electrolyte layer, respectively. The preliminary electrode assembly was placed inside a pouch and vacuum laminated to prepare a sealed preliminary electrode assembly. A polyimide (PI) film pressure auxiliary layer with a thickness of 50 μm was placed on the upper and lower surfaces of the sealed preliminary electrode assembly, respectively. The pouch had a multilayer structure in which PET (polyethylene terephthalate) layers and aluminum layers were alternately laminated.

[0250] A pre-electrode assembly with a pressurized auxiliary layer was immersed in a pressurized medium and subjected to a Warm Isostatic Press (WIP) at 85 ℃ and 500 MPa to manufacture an all-solid-state secondary battery.

[0251] The pressurizing auxiliary layer was removed after the warm hydrostatic press.

[0252] Examples 7 to 10

[0253] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that the thickness or material of the pressurized auxiliary layer was changed. Refer to Table 1 for the pressurized auxiliary layer.

[0254] Comparative Example 1

[0255] An all-solid-state secondary battery was manufactured using the same method as in Example 1, except that the pressurized auxiliary layer was omitted.

[0256] Comparative Example 2

[0257] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the pressurized auxiliary layer was changed to an aluminum sheet with a thickness of 1 mm.

[0258] Comparative Example 3

[0259] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that the pressurized auxiliary layer was omitted and a carbon coating layer was added on one side of the positive current collector.

[0260] The carbon coating layer was prepared by coating a coating composition containing 1.6 wt% carbon nanotubes, 1.6 wt% PVDF-HFP copolymer, and octyl acetate solvent onto one side of an aluminum foil anode current collector, drying at atmospheric pressure in air at 70°C for 1 hour, and then vacuum drying at 70°C for 7 hours. The thickness of the coating layer was 35 μm.

[0261] Comparative Example 4

[0262] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the pressurized auxiliary layer was omitted.

[0263] Evaluation Example 1: Evaluation of surface roughness of anode current collector

[0264] The surface roughness of the first surface adjacent to the positive active material layer of the all-solid-state secondary battery prepared in Examples 1 to 10 and Comparative Examples 1 to 3 and the second surface opposite thereto was measured, and the measurement results are shown in Table 1.

[0265] The surface roughness of the second plane was measured using an optical microscope. After measuring the surface of the second plane with an optical microscope, a surface profile for the second plane was derived from the measured image, and from this, the maximum roughness (R) of the second plane y2 ) was measured. FIG. 8 is a surface profile of the second surface of the positive current collector of the all-solid-state secondary battery prepared in Example 1 and Comparative Example 1. In FIG. 8, the maximum roughness (R) y2 ) is the maximum value of the reduced thickness (i.e., depth). In Fig. 8, the y-axis is the depth of depression from the reference point. The x-axis is the distance from the reference point.

[0266] As shown in Fig. 8, the surface roughness of the positive current collector of the all-solid-state secondary battery prepared in Example 1 was shown to be increased compared to the surface roughness of the positive current collector of the all-solid-state secondary battery prepared in Comparative Example 1.

[0267] The surface roughness of the first plane was measured from scanning electron microscope images of the cross-section of the all-solid-state secondary battery.

[0268] Figure 9 is a scanning electron microscope image of a cross-section of the positive electrode of the all-solid-state secondary battery prepared in Example 4.

[0269] As shown in Fig. 9, it was confirmed that the positive current collector of the all-solid-state secondary battery manufactured in Example 4 has an uneven surface formed on the first surface and the second surface, respectively, including a depression and a protrusion.

[0270] Figure 10 is a scanning electron microscope image of a cross-section of the positive electrode of the all-solid-state secondary battery prepared in Comparative Example 1.

[0271] As shown in FIG. 10, it was confirmed that the positive current collector of the all-solid-state secondary battery manufactured in Example 4 did not have an uneven surface including a depression and a protrusion formed on the second surface.

[0272] In Table 1, RP stands for Roll Press and WIP for Hot Hydrostatic Press. The PET film is a laminated film in which PET layers with a thickness of 60 μm and aluminum metal layers with a thickness of 30 μm are alternately laminated.

[0273] pressurized auxiliary layer pressurization method Second surface maximum roughness (R y2 ) [㎛] 1st surface maximum roughness (R y1 ) [㎛] Example 1 20 µm thick PI film RP 3.5 3.1 Example 2 40 µm thick PI film RP 4.2 5.1 Example 3 50 µm thick PI film RP 5.7 6.9 Example 4 100 µm thick PI film RP 5.1 4.5 Example 5 200 µm thick PI film RP 4.1 3.5 Example 6 50 µm thick PI film WIP 4.0 4.7 Example 7 100 µm thick PI film WIP 4.6 5.4 Example 8 500 µm thick PI film WIP 3.8 3.2 Example 9 600 µm thick PET film WIP 4.0 4.2 Example 10 900 µm thick PET film WIP 4.4 5.1 Comparative Example 1 - RP 1.3 0.2 Comparative Example 2 1 mm thick Al sheet WIP 1.4 0.3 Comparative Example 3 - RP 1.3 3.2

[0274] As shown in Table 1, the anode current collectors of Examples 1 to 10 used a pressurizing auxiliary layer, so that the maximum roughness of the second surface was 1.5 μm or more and the maximum roughness of the first surface was 1.0 μm or more.

[0275] Evaluation Example 2: Evaluation of Porosity of Anode Active Material Layer

[0276] The porosity was measured by measuring the area of ​​pores in the total area of ​​the positive active material layer from scanning electron microscope images of the cross-sections of the all-solid-state secondary batteries of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4. The porosity was calculated from the following Equation 1.

[0277] <Mathematical Formula 1>

[0278] Porosity = [Pore Area / Anode Active Material Layer Area] × 100

[0279] The measurement results are shown in Table 2 below.

[0280] pressurized auxiliary layer pressurization method Porosity [%] Example 1 20 µm thick PI film RP 11 Comparative Example 1 - RP 17 Comparative Example 2 1 mm thick Al sheet WIP 4.3 Comparative Example 4 - WIP 9.2

[0281] As shown in Table 2, Example 1 and Comparative Example 2, which were pressurized using a pressurizing auxiliary layer, each had a reduced porosity compared to Comparative Example 1 and Comparative Example 4, which did not have a pressurizing auxiliary layer.

[0282] In addition, it was confirmed that as the porosity decreased, the ionic conductivity of the positive active material layer of Example 1 increased compared to the ionic conductivity of the positive active material layer of Comparative Example 1.

[0283] Evaluation Example 3: Measurement of Charge / Discharge Characteristics (I)

[0284] The charge and discharge characteristics of the all-solid-state secondary batteries prepared in Examples 1 to 10 and Comparative Examples 1 to 3 were measured under pressure using a pressing jig. The pressing jig consists of a pair of pressing plates. An all-solid-state secondary battery was placed between a pair of pressing plates, and the all-solid-state secondary battery was pressed by reducing the gap between the pressing plates.

[0285] For the all-solid-state secondary batteries prepared in Examples 1 to 10 and Comparative Examples 1 to 3, constant current charging was performed at 45°C at a constant current of 0.1 C until the voltage reached 4.5 V (vs. Li), and then cut-off was performed at a current rate of 0.02 C while maintaining 4.5 V in constant voltage mode. Subsequently, discharge was performed at a constant current rate of 0.1 C until the voltage reached 2.5 V (vs. Li) during discharge. (First cycle)

[0286] The lithium battery, having undergone the first cycle, was charged at a constant current rate of 0.33 C at 25°C until the voltage reached 4.5 V (vs. Li), and then cut off at a current rate of 0.02 C while maintaining 4.5 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 0.33 C until the voltage reached 2.5 V (vs. Li) during discharge. (Second Cycle)

[0287] The lithium battery, having undergone the second cycle, was charged at a constant current rate of 1.0 C at 25°C until the voltage reached 4.5 V (vs. Li), and then cut off at a current rate of 0.02 C while maintaining 4.5 V in constant voltage mode. Subsequently, it was discharged at a constant current rate of 1.0 C until the voltage reached 2.5 V (vs. Li) during discharge. (Third cycle)

[0288] The results of the charge / discharge characteristic measurements are shown in Table 3 below.

[0289] The charge / discharge efficiency was calculated from the following mathematical formula 1.

[0290] <Mathematical Formula 2>

[0291] Charge / Discharge Efficiency (%) = [Third Cycle Discharge Capacity / Third Cycle Charge Capacity] × 100

[0292] pressurized auxiliary layer pressurization method 0.1C Discharge Capacity [mAh / g] Charge / Discharge Efficiency [%] Example 1 20 µm thick PI film RP 211 83.0 Example 2 40 µm thick PI film RP 207 83.0 Example 3 50 µm thick PI film RP 214 83.1 Example 4 100 µm thick PI film RP 209 82.5 Example 5 200 µm thick PI film RP 203 81.8 Example 6 50 µm thick PI film WIP 202 81.9 Example 7 100 µm thick PI film WIP 203 82.0 Example 8 500 µm thick PI film WIP 201 81.8 Example 9 600 µm thick PET film WIP 200 82.0 Example 10 900 µm thick PET film WIP 206 82.1 Comparative Example 1 - RP 187 79.4 Comparative Example 2 1 mm thick Al sheet WIP 191 80.4 Comparative Example 3 - RP 181 80.6

[0293] As shown in Table 3, the all-solid-state secondary batteries of Examples 1 to 10 showed improved discharge capacity and charge / discharge efficiency compared to the all-solid-state secondary batteries of Comparative Examples 1 to 3.

[0294] Although an exemplary embodiment has been described above, it is not limited thereto. It is possible to implement the invention with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the invention. Explanation of the symbols

[0295] 10 anodes 11 positive current collector 12 positive electrode active material layer 20 cathodes 21 Cathode current collector 22 Cathode active material layer 30 solid electrolyte layer 30a First solid electrolyte layer 0b Second solid electrolyte layer 40 protective layer 50 pressurized auxiliary layer 50a, 50aa, 50ab first pressurized auxiliary layer 50b, 50ba, 50bb second pressurized auxiliary layer 60, 60a, 60b rollers 100 All-solid-state secondary batteries

Claims

Claim 1 It comprises a positive current collector and a positive active material layer containing a solid electrolyte on the positive current collector, wherein the positive current collector comprises a first surface adjacent to the positive active material layer and a second surface opposing the first surface, and the maximum roughness (R) of the second surface of the positive current collector. y2 A cathode for an all-solid-state secondary battery having a highest surface roughness value of 1.5 μm or more. Claim 2 In claim 1, the maximum roughness (R) of the first surface of the positive current collector y1 Anode having a ) of 1.0 μm or more. Claim 3 An anode according to claim 1, wherein the maximum roughness of the second surface of the anode current collector is 15% or more of the thickness of the anode current collector. Claim 4 An anode according to claim 1, wherein the maximum roughness of the first surface of the anode current collector is 5% or more of the thickness of the anode current collector. Claim 5 In claim 1, the maximum roughness (R) of the first surface of the positive current collector y1 ) is the maximum roughness (R) of the second surface y2 Larger than ) positive electrode. Claim 6 The anode according to claim 1, wherein the thickness of the anode current collector is 2 to 100 μm. Claim 7 The anode according to claim 1, wherein the first surface and the second surface of the anode current collector each comprise an uneven surface including a convex and a concave portion. Claim 8 In the first aspect, the positive active material layer has a first positive active material layer depression, the first surface of the positive current collector has a first positive current collector protrusion that protrudes in the direction of the positive active material layer corresponding to the first positive active material layer depression, and the second surface of the positive current collector has a first positive current collector depression that is depressed in the direction of the positive active material layer corresponding to the first positive current collector protrusion. Claim 9 In claim 8, the anode is such that the radius of curvature of the cross-section of the first anode current collector's recess is larger than the radius of curvature of the cross-section of the first anode current collector's protruding portion. Claim 10 In claim 8, the anode having a radius of curvature of the cross-section of the first anode current collector depression of 1000 μm or less. Claim 11 A positive electrode, wherein the positive electrode active material layer has a first positive electrode active material layer protrusion, the first surface of the positive electrode current collector has a second positive electrode current collector recess that is recessed in the opposite direction of the positive electrode active material layer corresponding to the first positive electrode active material layer protrusion, and the second surface of the positive electrode current collector has a second positive electrode current collector protrusion that is protruded in the opposite direction of the positive electrode active material layer corresponding to the second positive electrode current collector recess. Claim 12 In claim 11, the anode is such that the radius of curvature of the cross-section of the second anode current collector protrusion is larger than the radius of curvature of the cross-section of the second anode current collector depression. Claim 13 In claim 11, the anode having a radius of curvature of the cross-section of the second anode current collector protrusion of 1000 μm or less. Claim 14 An all-solid-state secondary battery comprising: an anode according to any one of claims 1 to 13; a cathode; and a solid electrolyte layer between the anode and the cathode. Claim 15 A solid-state secondary battery according to claim 14, wherein the solid electrolyte layer comprises a first solid electrolyte layer disposed adjacent to the anode and a second solid electrolyte layer disposed adjacent to the cathode, wherein the porosity of the first solid electrolyte layer is lower than the porosity of the second solid electrolyte layer. Claim 16 A method for manufacturing an all-solid-state secondary battery, comprising: a step of preparing an anode-solid electrolyte layer laminate by applying a first pressurization to an anode and a solid electrolyte layer together with a first pressurization auxiliary layer; and a step of preparing an all-solid-state secondary battery by applying a second pressurization to the anode-solid electrolyte layer laminate and the cathode-solid electrolyte layer laminate together with a second pressurization auxiliary layer. Claim 17 A method for manufacturing an all-solid-state secondary battery according to claim 16, wherein the first pressurizing auxiliary layer and the second pressurizing auxiliary layer independently comprise a polymer, a metal, wood, or a combination thereof, wherein the polymer comprises polyimide (PI), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polystyrene (PS), polycarbonate (PC), polyvinyl chloride (PVC), polyvinyl alcohol, polyacrylate, polyethylene, polypropylene, polystyrene, polyacisobutylene, polyvinyl chloride, vinyl acetate resin, polytetrafluoroethylene, polyacrylonitrile, polyketacrylate methyl tetron, nylon, bakelite, urea resin, polysiloxane, or a combination thereof, and the metal comprises a metal belonging to groups 2 to 16 of the periodic table. Claim 18 A method for manufacturing an all-solid-state secondary battery according to claim 16, wherein the thickness of the first pressurizing auxiliary layer and the second pressurizing auxiliary layer is greater than the thickness of the positive current collector, and the thickness of the first pressurizing auxiliary layer and the second pressurizing auxiliary layer is 1 mm or less. Claim 19 A method for manufacturing an all-solid-state secondary battery according to claim 16, wherein the first and second pressurizations are performed independently of each other by a roll press, a plate press, a warm isostatic press (WIP), a cold isostatic press (CIP), or a hot isostatic press (HIP). Claim 20 A method for manufacturing an all-solid-state secondary battery according to claim 16, wherein the pressure of the first pressurization is greater than the pressure of the second pressurization, and the pressure of the first pressurization is 10 times or more the pressure of the second pressurization.

Images