All-solid-state secondary battery

Abstract

An all-solid-state secondary battery is provided. The all-solid-state secondary battery includes a positive electrode layer, a negative electrode layer, and a solid-state electrolyte layer between the positive electrode layer and the negative electrode layer, in which the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side of the positive electrode current collector, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side of the negative electrode current collector, the first negative electrode active material layer includes a first negative electrode active material and a second negative electrode active material each capable of forming an alloy or a compound with lithium, and a fibrous carbon-based material, and a ratio (B / A) of an initial charge capacity (B) of the first negative electrode active material layer to an initial charge capacity (A) of the positive electrode active material layer is in a range of about 0.01 to about 0.75.

Description

[0001] This application claims the priority and benefit of Korean Patent Application No. 10-2023-0187569, filed with the Korean Intellectual Property Office on December 20, 2023, and Korean Patent Application No. 10-2024-0064133, filed with the Korean Intellectual Property Office on May 16, 2024, the entire contents of each of which are incorporated herein by reference. Technical Field

[0002] One or more embodiments of the present disclosure relate to a all-solid-state secondary battery. Background Art

[0003] Recently, with the rapid spread and popularization of electronic devices using batteries (such as mobile phones, laptop computers, and / or electric vehicles), the demand for batteries (e.g., secondary (rechargeable) batteries having a relatively high energy density and high capacity) has increased rapidly. For example, research and development for improving the performance of such secondary batteries (e.g., lithium secondary batteries) have been actively conducted or pursued. A lithium secondary battery is a battery including an electrolyte and a positive electrode and a negative electrode, each of the positive electrode and the negative electrode including an active material capable of intercalating and deintercalating lithium ions. When lithium ions are intercalated into / from the positive electrode and the negative electrode (e.g., when), the lithium secondary battery generates electric energy through oxidation and reduction reactions.

[0004] Recently, according to industrial demands, batteries having a relatively high energy density and high safety have been actively developed. For example, lithium batteries are used in one or more suitable applications including information devices, communication devices, vehicles, etc. Vehicles are related to the well-being of users, so their safety is important and crucial.

[0005] A short circuit in a lithium battery using a liquid electrolyte may increase the possibility of fire and / or explosion. An all-solid-state secondary battery using a solid electrolyte instead of a liquid electrolyte has been proposed. Compared with a liquid electrolyte, a solid electrolyte has a lower possibility of catching fire.

[0006] An all-solid-state secondary battery uses a solid electrolyte instead of a liquid electrolyte, and thus can reduce the possibility of fire and / or explosion. Therefore, an all-solid-state battery can provide improved and desired safety. Summary of the Invention

[0007] One or more aspects of embodiments of the present disclosure relate to an all-solid-state secondary battery in which a fibrous carbon-based material and a binder are included in a negative electrode active material layer having an initial charge capacity lower than that of a positive electrode active material layer, thereby improving cycle characteristics and suppressing or reducing volume changes during charging or discharging.

[0008] Other aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the presented embodiments of the disclosure.

[0009] According to one or more embodiments of the present disclosure, a all-solid-state secondary battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side (e.g., one side) of the positive electrode current collector, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side (e.g., one side) of the negative electrode current collector. The first negative electrode active material layer includes: 1) a) a first negative electrode active material (e.g., in the form of particles) and b) a second negative electrode active material (e.g., in the form of particles), both (i.e., the first negative electrode active material and the second negative electrode active material) capable of forming an alloy or a compound with lithium; and 2) a fibrous carbonaceous material. The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is in the range of about 0.01 to about 0.75. The initial charge capacity of the positive electrode active material layer is determined by charging from the first open-circuit voltage to the maximum charge voltage vs. Li / Li + to determine, and the initial charge capacity of the first negative electrode active material layer is determined by charging from the second open-circuit voltage to a voltage of about 0.01 V vs. Li / Li + to determine.

[0010] According to one or more embodiments of the present disclosure, a all-solid-state secondary battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side (e.g., one side) of the positive electrode current collector, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side (e.g., one side) of the negative electrode current collector. The first negative electrode active material layer includes: 1) a first negative electrode active material (e.g., in the form of particles) capable of forming an alloy or a compound with lithium; 2) a second negative electrode active material (e.g., in the form of particles); and 3) a fibrous carbonaceous material.

[0011] According to one or more embodiments of the present disclosure, a all-solid-state secondary battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side (e.g., one side or opposite two sides) of the positive electrode current collector. The positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material (e.g., in the form of particles), and the lithium-containing sulfide-based positive electrode active material includes a complex containing Li2S. The negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one surface (e.g., one surface) of the negative electrode current collector. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the present disclosure and, together with the description, are used to explain the principles of the present disclosure. Through the following description with reference to the accompanying drawings, the above and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent, in which: Figure 1 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 2 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 3 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 4 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 5 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 6 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 7 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 8 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 9 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 10 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; Figure 11 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure; and Figure 12 is a cross-sectional view of a all-solid-state secondary battery according to one or more embodiments of the present disclosure. Detailed Description

[0013] Reference will now be made in more detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein, throughout the present disclosure, like reference numerals refer to like elements and, for the sake of brevity, a repeated description thereof may not be provided. In this regard, the presented embodiments may have different forms and should not be construed as limited to the description set forth herein. Accordingly, the embodiments of the present disclosure are described only by referring to the accompanying drawings to explain aspects of the present disclosure. As used herein, the term "and / or" or "or" may include any combination and all combinations of one or more of the related listed items. When expressions such as "at least one of...", "one of...", and "selected from..." are placed before / after a list of elements, they modify the entire list of elements and not individual elements in the list. For example, "at least one of a, b, or c", "at least one selected from a, b, and c", "at least one selected from a to c", etc. may indicate only a, only b, only c, both a and b (e.g., a and b simultaneously), both a and c (e.g., a and c simultaneously), both b and c (e.g., b and c simultaneously), all of a, b, and c, or variations thereof. The " / " used herein may be interpreted as "and" or "or" depending on the circumstances.

[0014] Unless otherwise defined, all terms (including technical and scientific terms) used in the present disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure pertains. In one or more embodiments, it will also be understood that terms (such as those defined in a general dictionary) should be interpreted as having a meaning consistent with their meaning in the relevant art and the context of the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0015] Embodiments are described in the present disclosure with reference to cross-sectional views that are schematic illustrations of idealized embodiments. Thus, for example, variations in the shape of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. In one or more embodiments, the embodiments described in the present disclosure should not be construed as limited to the specific shaped regions shown in the present disclosure, but may include, for example, shape deviations caused by manufacturing. For example, regions shown or described as flat may generally be rough and / or may have non-linear features. Additionally, corners drawn as sharp corners may be rounded. In one or more embodiments, the regions shown in the drawings are schematic in nature and their shapes are not intended to show the actual shape of the regions and are not intended to limit the scope of the appended claims.

[0016] However, the present disclosure may be implemented in different forms and should not be construed as limited to one or more of the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements.

[0017] When describing an element "on" another element, it will be understood that the element may be disposed directly on the other element or another element may be interposed therebetween. In contrast, when describing an element "directly on" another element, no other element is interposed therebetween.

[0018] It will be understood that although the terms "first", "second", and "third" may be used herein to describe one or more suitable elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. In one or more embodiments, the first element, first component, first region, first layer, or first portion described may be referred to as the second element, second component, second region, second layer, or second portion without departing from the teachings of the present disclosure.

[0019] The terms used herein are only intended to describe particular embodiments and are not intended to limit the present disclosure. As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms (including "at least one"). "At least one" should not be construed as limited to the singular. As used herein, the term "and / or" or "or" may include any combination and all combinations of one or more of the associated listed items. When the terms "comprising", "including", and / or their variants are used in the detailed description, it indicates the presence of the stated features, regions, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or their groups. Further, when describing embodiments of the present disclosure, the use of "may" means "one or more embodiments of the present disclosure".

[0020] Spatial relative terms such as "under", "below", "lower", "above", and "upper" can be used herein to facilitate the description of the relationship of one element or feature to another element or feature. It will be understood that the spatial relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, when the device in the figures is flipped (e.g., when), an element or feature described as "under" or "below" other elements or features will then be "above" or "over" the other elements or features. In one or more embodiments, the exemplary term "under" can cover both orientations, above and below (e.g., covering both above and below simultaneously). The device can be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatial relative terms used herein can be interpreted accordingly.

[0021] As used herein, the term "group" refers to the groups of the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system from Group I to Group XVIII.

[0022] Unless otherwise defined herein, particle size / particle diameter can be the average particle size / particle diameter. For example, particle size / particle diameter can refer to the average particle size / particle diameter (D50), and the average particle size / particle diameter (D50) refers to the diameter / size of the particles with a cumulative volume of 50 vol% in the particle size distribution. The average particle size / particle diameter (D50) can be measured by methods well-suited to those skilled in the art (e.g., by using a particle size analyzer, such as the LA-950 laser particle size analyzer from HORIBA, transmission electron microscopy (TEM), or scanning electron microscopy (SEM)). In one or more embodiments, it can be measured by using a measuring device utilizing dynamic light scattering, performing data analysis to count the number of particles in each particle size range, and then the value of the average particle size / particle diameter (D50) can be easily obtained therefrom by calculation. In one or more embodiments, the average particle size / particle diameter (D50) can be measured by using the laser diffraction method. During measurement by laser diffraction, the particles to be measured can be dispersed in a dispersion medium and then introduced into a commercially available laser diffraction particle size measuring device (e.g., the MT3000 from Microtrac), ultrasonic waves at 28 kHz can be irradiated thereon with an output power of about 60 W, and then the average particle size / particle diameter (D50) based on the 50% particle size distribution can be calculated in the measuring device.

[0023] In the present disclosure, the term "particle size" or "grain size" refers to the average diameter / size when the particles are spherical (e.g., when), and refers to the average major axis length when the particles are non-spherical. "Average particle size / size" refers to, for example, the median particle size / size (D50). D50 refers to the particle size / grain size corresponding to 50% cumulative volume when calculating the particle size distribution measured by the laser diffraction method from particles with smaller grain sizes to particles with larger grain sizes.

[0024] When calculating the particle size distribution measured by the laser diffraction method from particles with smaller grain sizes to particles with larger grain sizes, D90 refers to the particle size / grain size corresponding to 90% cumulative volume.

[0025] When calculating the particle size distribution measured by the laser diffraction method from particles with smaller grain sizes to particles with larger grain sizes, D10 refers to the particle size / grain size corresponding to 10% cumulative volume.

[0026] As used herein, the term "metal" refers to all metals and metalloids (such as silicon and germanium) in the elemental state or ionic state.

[0027] As used herein, the term "alloy" refers to a mixture or composition of two or more metals.

[0028] As used herein, the term "electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0029] As used herein, the term "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0030] As used herein, the term "negative electrode active material" refers to a negative electrode material that can undergo lithiation and delithiation.

[0031] As used herein, the term "lithiation" and its variants refer to the process of adding lithium to the electrode active material.

[0032] As used herein, the term "delithiation" and its variants refer to the process of removing lithium from the electrode active material.

[0033] As used herein, the term "charging" and its variants refer to the process of providing electrochemical energy to the battery.

[0034] As used herein, the term "discharging" and its variants refer to the process of removing electrochemical energy from the battery.

[0035] As used herein, the terms "positive electrode" and "positive pole" refer to the electrode where electrochemical reduction and lithiation occur during discharge.

[0036] As used herein, the terms "negative electrode" and "cathode" refer to the electrode at which electrochemical oxidation and de-lithiation occur during discharge.

[0037] While example embodiments will be described herein, alternatives, modifications, variations, improvements, and substantial equivalents may occur to the applicant or other technicians in the art that are presently unforeseen or may be unforeseen. Accordingly, the appended claims, as filed and as may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0038] Hereinafter, a all-solid-state secondary battery according to one or more embodiments will be described in more detail.

[0039] All-solid-state secondary battery A all-solid-state secondary battery according to one or more embodiments may include a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer. The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side (e.g., one side or opposite two sides) of the positive electrode current collector, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side (e.g., one side) of the negative electrode current collector. The first negative electrode active material layer includes: 1) a) a first negative electrode active material (e.g., in particulate form) and b) a second negative electrode active material (e.g., in particulate form), both capable of forming an alloy or compound with lithium; and 2) a fibrous carbonaceous material. The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is in the range of about 0.01 to about 0.75. The initial charge capacity of the positive electrode active material layer is determined by charging from the first open circuit voltage (OCV) to the maximum charge voltage vs. Li / Li + and the initial charge capacity of the first negative electrode active material layer is determined by charging from the second OCV to about 0.01V vs. Li / Li + to determine.

[0040] The fibrous carbonaceous material may provide a conduction (e.g., electron conduction) path between the plurality of negative electrode active materials (e.g., a plurality of negative electrode active material particles), such that an increase in the internal resistance of the first negative electrode active material layer can be more easily suppressed or reduced. An increase in the internal resistance of the all-solid-state secondary battery can be suppressed or reduced.

[0041] The fibrous carbonaceous material may be used as a support / buffer between the plurality of negative electrode active material particles, such that a volume change of the first negative electrode active material layer caused by precipitation and / or dissolution of lithium during charging or discharging can be effectively alleviated. In one or more embodiments, a volume change of the all-solid-state secondary battery during charging or discharging can be reduced.

[0042] In one or more embodiments, a binder may be included to bond the negative electrode active material and the fibrous carbonaceous material, thereby more effectively suppressing or reducing the disconnection of the conduction path between the negative electrode active material and the fibrous carbonaceous material due to the volume change of the negative electrode active material during charging or discharging in the process of depositing and / or dissolving lithium. The non-uniformity of the electrode reaction of the all-solid-state secondary battery can also be suppressed or reduced.

[0043] The binder can also improve the adhesion between the first negative electrode active material layer and the solid electrolyte layer and / or between the first negative electrode active material layer and the negative electrode current collector. For example, the binder can improve the wettability between the first negative electrode active material layer and the solid electrolyte layer and / or between the first negative electrode active material layer and the negative electrode current collector. In one or more embodiments, the binder can more effectively reduce the increase in the interfacial resistance caused by the formation of pores, etc. between the first negative electrode active material layer and the solid electrolyte layer and / or between the first negative electrode active material layer and the negative electrode current collector. The cycle characteristics of the all-solid-state secondary battery can be improved.

[0044] When the first negative electrode active material layer does not include a binder (for example), the first negative electrode active material layer can be separated from the solid electrolyte layer and / or the negative electrode current collector, so the surface of the solid electrolyte layer and / or the surface of the negative electrode current collector will be exposed. For example, the exposed negative electrode current collector may cause a short circuit. The cycle characteristics of the all-solid-state secondary battery may deteriorate.

[0045] Referring to Figures 1 to 12 , the all-solid-state secondary battery 1 may include a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 may include a positive electrode current collector 11 and a positive electrode active material layer 12 on one side (for example, one side) of the positive electrode current collector 11. The negative electrode layer 20 may include a negative electrode current collector 21 and a first negative electrode active material layer 22 on one side (for example, one side) of the negative electrode current collector 21. The first negative electrode active material layer 22 may include: 1) a) a first negative electrode active material (for example, in the form of particles) and b) a second negative electrode active material (for example, in the form of particles), both of which are capable of forming an alloy or a compound with lithium; and 2) a fibrous carbonaceous material. The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer 12 may be in the range of about 0.01 to about 0.75. The initial charge capacity of the positive electrode active material layer 12 can be determined by charging from the first OCV to the maximum charging voltage vs. Li / Li + to determine. The initial charge capacity of the first negative electrode active material layer 22 can be determined by charging from the second OCV to a voltage of about 0.01 V vs. Li / Li + to determine.

[0046] Negative electrode layer Negative electrode layer: First negative electrode active material Reference Figures 1 to 12 , the negative electrode layer 20 may include a first negative electrode active material layer 22. The first negative electrode active material layer 22 may include a first negative electrode active material capable of forming an alloy or a compound with lithium.

[0047] The first negative electrode active material may be, for example, a negative electrode material capable of forming an alloy with lithium or a negative electrode material capable of forming a compound with lithium.

[0048] The first negative electrode active material layer 22 may include a first negative electrode active material, and the first negative electrode active material may have, for example, a particulate form. The size of the first negative electrode active material having a particulate form may be, for example, 2 micrometers (μm) or less, 1 μm or less, 500 nanometers (nm) or less, 300 nm or less, or 200 nm or less. In one or more embodiments, the size of the first negative electrode active material having a particulate form may be, for example, in the range of about 100 nm to about 2 μm, about 200 nm to about 2 μm, about 500 nm to about 2 μm, or about 500 nm to about 1.5 μm. In one or more embodiments, the size of the first negative electrode active material having a particulate form may be, for example, in the range of about 10 nm to about 2 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 300 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. The first negative electrode active material may have a size within such a range, and thus reversible insertion and / or deinsertion of lithium may be effectively performed during charging or discharging. The size of the first negative electrode active material may be, for example, the average particle diameter of the first negative electrode active material. The average particle diameter of the first negative electrode active material may be, for example, the median particle diameter (D50) measured by using a laser particle size distribution analyzer.

[0049] The aspect ratio of the first negative electrode active material may be, for example, 5 or less, 4 or less, 3 or less, or 2 or less. In one or more embodiments, the aspect ratio of the first negative electrode active material may be, for example, in the range of about 1 to about 5, about 1 to about 4, about 1 to about 3, or about 1 to about 2. The first negative electrode active material may have an aspect ratio within such a range, and thus may be more uniformly (e.g., substantially uniformly) distributed in the first negative electrode active material layer 22. In one or more embodiments, non-uniformity of volume change of the first negative electrode active material during charging or discharging may be suppressed or reduced. The aspect ratio of the first negative electrode active material may be measured, for example, by using a scanning electron microscope (SEM).

[0050] In one or more embodiments, the first negative electrode active material included in the first negative electrode active material layer 22 may include, for example, a first metal-based negative electrode active material.

[0051] The first metal-based negative electrode active material includes, for example, silicon (Si), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and / or a combination thereof (e.g., any suitable combination), but the embodiments of the present disclosure are not necessarily limited thereto. Any material (suitable material) can be used as long as the material can be used as the first metal-based negative electrode active material that can form an alloy or compound with lithium in the art. For example, nickel (Ni) cannot form an alloy with lithium, so nickel (Ni) cannot be the first metal-based negative electrode active material.

[0052] Negative electrode layer: fibrous carbon-based material In addition to the first negative electrode active material, the first negative electrode active material layer 22 may further include a fibrous carbon-based material.

[0053] In one or more embodiments, the first negative electrode active material layer 22 may include a mixture of a fibrous carbon-based material and a first negative electrode active material capable of forming an alloy or compound with lithium. For example, in one or more embodiments, the first negative electrode active material layer 22 may include a mixture of a fibrous carbon-based material and at least one first negative electrode active material selected from silicon (Si), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of 1) the fibrous carbon-based material and 2) silicon, etc. (e.g., the mixing ratio of the fibrous carbon-based material to silicon, etc.) may be, for example, a weight ratio in the range of about 99:1 to about 1:99, about 10:1 to about 1:10, about 1:1 to about 1:9, about 1:1 to about 1:8, about 1:1 to about 1:7, about 1:1 to about 1:6, about 1:1 to about 1:5, about 1:1 to about 1:4, or about 1:1 to about 1:3, but the embodiments of the present disclosure are not necessarily limited to such a range. The mixing ratio of the mixture can be selected according to the desired or required characteristics of the all-solid-state secondary battery 1. The fibrous carbon-based material and the first negative electrode active material may have such a composition, so that the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

[0054] In one or more embodiments, the first negative electrode active material layer 22 may include a mixture of first particles containing a metal (e.g., consisting of a metal) and second particles containing a fibrous carbonaceous material (e.g., consisting of a fibrous carbonaceous material). The metal may include, for example, silicon (Si), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and / or any suitable combination thereof. The content (e.g., amount) of the second particles may be in the range of about 1 wt% to about 99 wt%, about 1 wt% to about 70 wt%, about 10 wt% to about 70 wt%, about 11 wt% to about 60 wt%, or about 12 wt% to about 50 wt% relative to the total weight of the mixture of 100 wt%. The fibrous carbonaceous material may have a content (e.g., amount) within such a range, and thus, for example, may further improve the cycle characteristics of the all-solid-state secondary battery 1.

[0055] For example, the size of the first negative electrode active material capable of forming an alloy or compound with lithium may be smaller than the length of the fibrous carbonaceous material. The length of the fibrous carbonaceous material may be greater than the size of the first negative electrode active material, and thus the fibrous carbonaceous material may be used as a support and / or buffer between multiple first negative electrode active materials (e.g., between multiple first negative electrode active material particles). The fibrous carbonaceous material may be disposed between the multiple first negative electrode active materials to effectively relieve the stress caused by the volume change of the first negative electrode active material due to the precipitation and / or dissolution of lithium during charging or discharging. In one or more embodiments, the volume change of the first negative electrode active material layer 22 during charging or discharging may be more effectively suppressed or reduced. The ratio of the size of the first negative electrode active material to the length of the fibrous carbonaceous material may be, for example, in the range of about 1:10 to about 1:2,000, about 1:10 to about 1:1,000, about 1:10 to about 1:500, about 1:10 to about 1:200, about 1:10 to about 1:100, about 1:10 to about 1:50, or about 1:10 to about 1:20. The ratio of the size of the first negative electrode active material to the length of the fibrous carbonaceous material may be within such a range, and thus, for example, may further improve the cycle characteristics of the all-solid-state secondary battery 1.

[0056] The fibrous carbon-based material can be, for example, a conductive carbon-based material. The fibrous carbon-based material can have electrical conductivity (i.e., be an electronic conductor), and thus can provide a conduction path within the first negative electrode active material layer 22. The fibrous carbon-based material can more effectively reduce the internal resistance of the first negative electrode active material layer 22. In one or more embodiments, the cycle characteristics of the all-solid-state secondary battery 1 can be improved. Except for the fibrous carbon-based material, the first negative electrode active material layer 22 may not additionally include other carbon-based conductive materials. The first negative electrode active material layer 22 may not include (e.g., may exclude) other carbon-based conductive materials except for the fibrous carbon-based material, and thus the energy density of the first negative electrode active material layer 22 can be further improved.

[0057] In one or more embodiments, the aspect ratio of the fibrous carbon-based material can be, for example, 10 or greater, 20 or greater, 30 or greater, or 50 or greater. In one or more embodiments, the aspect ratio of the fibrous carbon-based material can be, for example, 2,000 or less, 1,000 or less, 500 or less, 200 or less, or 100 or less. In one or more embodiments, the aspect ratio of the fibrous carbon-based material can be, for example, in the range of about 10 to about 2,000, about 20 to about 2,000, about 30 to about 2,000, or about 50 to about 2,000. In one or more embodiments, the aspect ratio of the fibrous carbon-based material can be, for example, in the range of about 10 to about 2,000, about 10 to about 1,000, about 10 to about 500, about 10 to about 200, about 10 to about 100, about 10 to about 50, or about 10 to about 20. The aspect ratio of the fibrous carbon-based material can be, for example, the ratio of the length of the major axis (i.e., the length of the fibrous carbon-based material) of the fibrous carbon-based material to the length of the minor axis (i.e., the diameter of the fibrous carbon-based material) orthogonal to the major axis (e.g., perpendicular to the major axis). The "aspect ratio" used herein can refer to the average aspect ratio and can be determined from an SEM image. The fibrous carbon-based material can have an aspect ratio within such a range, and thus, due to the fibrous carbon-based material, the conduction path within the first negative electrode active material layer 22 can become longer (or the conduction path within the first negative electrode active material layer 22 can exist as longer). The fibrous carbon-based material can form a three-dimensional conductive network in the first negative electrode active material layer 22, thereby more effectively reducing the internal resistance of the first negative electrode active material layer 22. In one or more embodiments, the internal resistance of the all-solid-state secondary battery 1 can be reduced. For example, the high-rate characteristics of the all-solid-state secondary battery 1 can be improved.

[0058] The fibrous carbon-based material may include, for example, an amorphous fibrous carbon-based material, a crystalline fibrous carbon-based material, and / or a combination thereof (e.g., any suitable combination). In one or more embodiments, the fibrous carbon-based material may include an amorphous fibrous carbon-based material, and thus side reactions between lithium and the fibrous carbon-based material can be more effectively suppressed or reduced. The reversibility of the electrode reaction during charging or discharging of the all-solid-state secondary battery 1 can be improved, thereby improving the cycle characteristics of the all-solid-state secondary battery 1.

[0059] The diameter of the fibrous carbon-based material may be, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. In one or more embodiments, the diameter of the fibrous carbon-based material may be, for example, in the range of about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 10 nm. The fibrous carbon-based material may have a diameter within such a range so that the internal resistance of the first negative electrode active material layer 22 can be effectively reduced, and the fibrous carbon-based material can be easily dispersed in a solvent and / or a slurry during the preparation of the first negative electrode active material layer 22.

[0060] The length of the fibrous carbon-based material may be, for example, 1,000 μm or less, 100 μm or less, 50 μm or less, 10 μm or less, 5 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. In one or more embodiments, the length of the fibrous carbon-based material may be, for example, in the range of about 100 nm to about 1,000 μm, about 100 nm to about 500 μm, about 100 nm to about 100 μm, about 100 nm to about 50 μm, about 100 nm to about 10 μm, about 100 nm to about 5 μm, about 100 nm to about 2 μm, about 100 nm to about 1 μm, about 100 nm to about 500 nm, or about 100 nm to about 300 nm. In one or more embodiments, the length of the fibrous carbon-based material may be, for example, in the range of about 500 nm to about 1,000 μm, about 500 nm to about 500 μm, about 500 nm to about 100 μm, about 500 nm to about 50 μm, about 500 nm to about 10 μm, about 1 μm to about 10 μm, or about 2 μm to about 8 μm. When the length of the fibrous carbon-based material increases, the internal resistance of the electrode can be reduced.

[0061] The fibrous carbon-based material may include, for example, fibrous carbon nanostructures. The fibrous carbon nanostructures may include, for example, carbon nanofibers (CNF), carbon nanotubes (CNT), carbon nanobelts, and / or a combination thereof (e.g., any suitable combination).

[0062] The CNT may include, for example, a carbon nanotube primary structure, a carbon nanotube secondary structure formed by aggregating a plurality of carbon nanotube primary structures / particles, and / or a combination thereof (e.g., any suitable combination).

[0063] The carbon nanotube primary structure may be one (e.g., exactly one) carbon nanotube unit. The carbon nanotube unit may have a graphite sheet in the form of a cylinder with a nanoscale diameter and may have an sp 2 bond structure. Depending on the angle and structure of the graphite sheet bending, it may exhibit the characteristics of a conductor or a semiconductor. Depending on the number of bonds constituting the wall, the carbon nanotube unit may be classified as a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (DWCNT), or a multi-walled carbon nanotube (MWCNT). That is, carbon nanotubes can be classified into three main types or categories: single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT), and multi-walled carbon nanotubes (MWCNT). When the wall thickness of the carbon nanotube unit decreases, the resistance can be reduced.

[0064] The carbon nanotube primary structure may include, for example, SWCNT, DWCNT, MWCNT, and / or a combination thereof (e.g., any suitable combination). The diameter of the carbon nanotube primary structure may be, for example, 1 nm or greater, or 2 nm or greater. The diameter of the carbon nanotube primary structure may be, for example, 20 nm or less, or 10 nm or less. In one or more embodiments, the diameter of the carbon nanotube primary structure may be, for example, in the range of about 1 nm to about 20 nm, about 1 nm to about 15 nm, or about 1 nm to about 10 nm. The length of the carbon nanotube primary structure may be, for example, 100 nm or greater, or 200 nm or greater. The length of the carbon nanotube primary structure may be, for example, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. In one or more embodiments, the length of the carbon nanotube primary structure may be, for example, in the range of about 100 nm to about 2 μm, about 100 nm to about 1 μm, about 100 nm to about 500 nm, about 100 nm to about 400 nm, about 100 nm to about 300 nm, or about 200 nm to about 300 nm. The diameter and length of the carbon nanotube primary structure can be measured from SEM images or transmission electron microscope (TEM) images. In one or more embodiments, the diameter and / or length of the carbon nanotube primary structure can be measured by laser diffraction.

[0065] The secondary structure of carbon nanotubes can be a structure formed by clustering all or part of the primary structure of carbon nanotubes to form a bundle-type (or similar) or rope-type (or similar) nanostructure. The secondary structure of carbon nanotubes can include, for example, bundle-type (or similar) CNTs, rope-type (or similar) CNTs, and / or combinations thereof (e.g., any suitable combination). The diameter of the secondary structure of carbon nanotubes can be, for example, 2 nm or greater, or 3 nm or greater. The diameter of the secondary structure of carbon nanotubes can be, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. In one or more embodiments, the diameter of the secondary structure of carbon nanotubes can be, for example, in the range of about 2 nm to about 50 nm, about 2 nm to about 30 nm, or about 2 nm to about 20 nm. The length of the secondary structure of carbon nanotubes can be, for example, 500 nm or greater, 700 nm or greater, 1 μm or greater, or 10 μm or greater. The length of the secondary structure of carbon nanotubes can be, for example, 1,000 μm or less, 500 μm or less, or 100 μm or less. In one or more embodiments, the length of the secondary structure of carbon nanotubes can be in the range of, for example, about 500 nm to 1,000 μm, about 500 nm to about 500 μm, about 500 nm to about 200 μm, about 500 nm to about 100 μm, about 500 nm to about 50 μm, about 500 nm to about 10 μm, about 1 μm to about 10 μm, or about 2 μm to about 8 μm. The diameter and length of the secondary structure of carbon nanotubes can be measured from SEM images or by optical microscopy. In one or more embodiments, the diameter and / or length of the secondary structure of carbon nanotubes can be measured by laser diffraction.

[0066] The secondary structure of carbon nanotubes can be dispersed in, for example, a solvent or the like to be converted into the primary structure of carbon nanotubes, and then can be used to prepare the first negative electrode active material layer 22.

[0067] Negative electrode layer: Second negative electrode active material Reference Figures 1 to 12 , the negative electrode layer 20 can include the first negative electrode active material layer 22. The first negative electrode active material layer 22 can include the second negative electrode active material.

[0068] The second negative electrode active material can be, for example, a negative electrode material capable of forming an alloy with lithium or a negative electrode material capable of forming a compound with lithium. The second negative electrode active material can be different from the first negative electrode active material. For example, the size of the second negative electrode active material can be smaller than the size of the first negative electrode active material. In one or more embodiments, the size of the second negative electrode active material can be, for example, 80% or less, 60% or less, 40% or less, 20% or less, or 10% or less of the size of the first negative electrode active material.

[0069] The first negative electrode active material layer 22 may include a second negative electrode active material, and the second negative electrode active material may have, for example, a particulate form (e.g., in the form of particles). The size of the second negative electrode active material having a particulate form may be, for example, less than 1 μm, 500 nm or less, 300 nm or less, or 100 nm or less. In one or more embodiments, the size of the second negative electrode active material having a particulate form may be, for example, in the range of about 10 nm to about 1 μm, about 10 nm to about 900 nm, about 10 nm to about 700 nm, about 10 nm to about 500 nm, about 10 nm to about 300 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. The second negative electrode active material may have a size within such a range, and thus lithium can be more effectively reversibly intercalated and / or deintercalated during charging or discharging. The size of the second negative electrode active material may be, for example, the average particle diameter of the second negative electrode active material. The average particle diameter of the second negative electrode active material may be, for example, the median particle diameter (D50) measured by using a laser particle size distribution analyzer.

[0070] The aspect ratio of the second negative electrode active material may be, for example, 5 or less, 4 or less, 3 or less, or 2 or less. In one or more embodiments, the aspect ratio of the second negative electrode active material may be, for example, in the range of about 1 to about 5, about 1 to about 4, about 1 to about 3, or about 1 to about 2. The second negative electrode active material may have an aspect ratio within such a range, and thus can be more uniformly (e.g., substantially uniformly) distributed in the first negative electrode active material layer 22. In one or more embodiments, the non-uniformity of the volume change of the second negative electrode active material during charging or discharging can be suppressed or reduced. The aspect ratio of the second negative electrode active material may be measured, for example, by using SEM.

[0071] In one or more embodiments, the second negative electrode active material included in the first negative electrode active material layer 22 may include, for example, a carbon-based negative electrode active material, a second metal-based negative electrode active material different from the first negative electrode active material, and / or a combination thereof (e.g., any suitable combination).

[0072] The carbon-based negative electrode active material may include, for example, amorphous carbon, crystalline carbon, porous carbon, and / or a combination thereof (e.g., any suitable combination).

[0073] In one or more embodiments, the carbon-based negative electrode active material may be, for example, amorphous carbon. Examples of amorphous carbon may include carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, etc., but the embodiments of the present disclosure are not necessarily limited thereto. Any material may be used as long as the material can be classified as amorphous carbon in the art. Amorphous carbon may be carbon that does not have crystallinity or has very low crystallinity, and may be different from crystalline carbon or graphite-based carbon.

[0074] In one or more embodiments, the carbonaceous negative electrode active material may be, for example, porous carbon. The pore volume of the porous carbon may be, for example, in the range of about 0.1 cc / g to about 10.0 cc / g, about 0.5 cc / g to about 5 cc / g, or about 0.1 cc / g to about 1 cc / g. The average pore diameter of the porous carbon may be, for example, in the range of about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 10 nm. The BET (Brunauer-Emmett-Teller) specific surface area of the porous carbon may be, for example, in the range of about 100 m 2 / g to about 3,000 m 2 / g.

[0075] The second metallic negative electrode active material may include at least one selected from gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but embodiments of the present disclosure are not necessarily limited thereto. Any material may be used as long as the material can be used as a metallic negative electrode active material or a metalloid negative electrode active material that forms an alloy or a compound with lithium in the art. For example, nickel (Ni) cannot form an alloy with lithium, so nickel (Ni) cannot be a metallic negative electrode active material.

[0076] The first negative electrode active material layer 22 may include one type (or species) of the second negative electrode active material among such second negative electrode active materials and / or a mixture of a plurality of different second negative electrode active materials (for example, any suitable one). For example, in one or more embodiments, the first negative electrode active material layer 22 may include only amorphous carbon, or may include at least one selected from gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In one or more embodiments, the first negative electrode active material layer 22 may include a mixture of amorphous carbon and at least one selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). For example, the mixing ratio of the mixture of amorphous carbon and gold or the like may be, for example, a weight ratio in the range of about 99:1 to about 1:99, about 10:1 to about 1:2, about 5:1 to about 1:1, or about 4:1 to about 2:1, but embodiments of the present disclosure are not necessarily limited to such a range. The mixing ratio may be selected according to the desired or required characteristics of the all-solid-state secondary battery 1. The second negative electrode active material may have such a composition, so that the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

[0077] In one or more embodiments, the second negative electrode active material included in the first negative electrode active material layer 22 may include, for example, a mixture of first particles containing amorphous carbon (e.g., consisting of amorphous carbon) and second particles containing a second metal-based negative electrode active material (e.g., consisting of a second metal-based negative electrode active material). Non-limiting examples of the second metal-based negative electrode active material may include gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), and the like. The content (e.g., amount) of the second particles may be in the range of about 1 wt% to about 99 wt%, about 1 wt% to about 60 wt%, about 8 wt% to about 60 wt%, about 10 wt% to about 50 wt%, about 15 wt% to about 40 wt%, or about 20 wt% to about 30 wt% relative to the total weight of the mixture of 100 wt%. The second particles may have a content (e.g., amount) within such a range, and thus, for example, the cycle characteristics of the all-solid-state secondary battery 1 may be further improved.

[0078] In one or more embodiments, the first negative electrode active material layer 22 may include a second negative electrode active material, and the second negative electrode active material may include, for example, a composite negative electrode active material. The composite negative electrode active material may include, for example, a carbon-based support and a second metal-based negative electrode active material supported on the carbon-based support. The composite negative electrode active material may have a structure such that localization of the second metal-based negative electrode active material in the first negative electrode active material layer 22 can be prevented or reduced, and its substantially uniform distribution can be obtained. In one or more embodiments, the cycle characteristics of the all-solid-state secondary battery 1 including such a first negative electrode active material layer 22 may be further improved.

[0079] The second metal-based negative electrode active material supported on the carbon-based support may include, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, and / or a combination thereof (e.g., any suitable combination). Non-limiting examples of the metal may include gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), tellurium (Te), zinc (Zn), and the like. Non-limiting examples of the metal oxide may include gold oxide (Au), platinum oxide (Pt), palladium oxide (Pd), silver oxide (Ag), aluminum oxide (Al), bismuth oxide (Bi), tin oxide (Sn), tellurium oxide (Te), zinc oxide (Zn), and the like. The metal oxide may include, for example, Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Pd x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), Agx O y (where 0 < x ≤ 2 and 0 < y ≤ 1), Al x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Bi x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Sn x O y , (where 0 < x ≤ 1 and 0 < y ≤ 2), Te x O y (where 0 < x ≤ 1 and 0 < y ≤ 3), Zn x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), and / or their (e.g., any suitable) combination. In one or more embodiments, the composite of metal and metal oxide can include, for example, Au and Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3) composite, Pt and Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2) composite, Pd and Pd x O y (where 0 < x ≤ 1 and 0 < y ≤ 1) composite, Ag and Ag x O y (where 0 < x ≤ 2 and 0 < y ≤ 1) composite, Al and Al x O y (where 0 < x ≤ 2 and 0 < y ≤ 3) composite, Bi and Bi x O y (where 0 < x ≤ 2 and 0 < y ≤ 3) composite, Sn and Sn x O y , (where 0 < x ≤ 1 and 0 < y ≤ 2) composite, Te and Te x O y (where 0 < x ≤ 1 and 0 < y ≤ 3) composite, Zn and Zn x O y (where 0 < x ≤ 1 and 0 < y ≤ 1) composite, and / or their (e.g., any suitable) combination.

[0080] The carbonaceous support can include, for example, amorphous carbon. Examples of amorphous carbon can include carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, activated carbon, etc., but the embodiments of the present disclosure are not necessarily limited thereto. Any material can be used as long as the material can be classified as amorphous carbon in the art. Amorphous carbon can be carbon that does not have crystallinity or has very low crystallinity and can be different from crystalline carbon or graphite-like carbon.

[0081] In one or more embodiments, the composite negative electrode active material may have, for example, a particulate form (e.g., in the form of particles). The particle size of the composite negative electrode active material having a particulate form may be, for example, in the range of about 10 nm to about 2 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. The composite negative electrode active material may have a particle size within such a range, and thus the reversible insertion and / or extraction of lithium during charge / discharge can be made easier. The second metal-based negative electrode active material supported on the carbon-based support may have, for example, a particulate form (e.g., in the form of particles). The particle size of the second metal-based negative electrode active material may be, for example, in the range of about 1 nm to about 200 nm, about 1 nm to about 150 nm, about 5 nm to about 100 nm, or about 10 nm to about 50 nm. The carbon-based support may have, for example, a particulate form (e.g., in the form of particles). The particle size of the carbon-based support may be, for example, in the range of about 10 nm to about 2 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. The carbon-based support may have a particle size within such a range, and thus can be arranged more uniformly (e.g., substantially uniformly) in the first negative electrode active material layer 22. In one or more embodiments, the carbon-based support may include, for example, nanoparticles having a particle size of 500 nm or less. The particle size of the composite negative electrode active material, the particle size of the second metal-based negative electrode active material, and the particle size of the carbon-based support may each be, for example, an average particle size. The average particle size may be, for example, a median particle size (D50) measured by using a laser type (or kind) particle size distribution analyzer. In one or more embodiments, the average particle size may be automatically determined from an electron microscope image by using software, or may be manually determined based on manual calculation.

[0082] Negative electrode layer: Binder In one or more embodiments, the first negative electrode active material layer 22 may include a binder. The binder may be, for example, a polymer binder. The binder included in the first negative electrode active material layer 22 may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile (PAN), polymethyl methacrylate, etc., but the embodiments of the present disclosure are not necessarily limited thereto. Any material may be used as long as the material can be used as a binder in the art. The binder may be provided as a single binder or a plurality of different binders. In one or more embodiments, the binder may include, for example, a fluorine-based binder.

[0083] The first negative electrode active material layer 22 may include a binder and thus may be stabilized on the negative electrode current collector 21. In one or more embodiments, even though the volume and / or relative position of the first negative electrode active material layer 22 changes during the charge / discharge process, cracks in the first negative electrode active material layer 22 may still be suppressed or reduced. For example, when the first negative electrode active material layer 22 does not include a binder, the first negative electrode active material layer 22 may easily separate from the negative electrode current collector 21. At a portion of the negative electrode current collector 21 that is exposed due to the separation of the first negative electrode active material layer 22 from the negative electrode current collector 21, the negative electrode current collector 21 may come into contact with the solid electrolyte layer 30, which may increase the likelihood of a short circuit occurring. In one or more embodiments, the first negative electrode active material layer 22 may be formed, for example, by applying a slurry in which materials constituting the first negative electrode active material layer 22 are dispersed onto the negative electrode current collector 21 and drying the slurry. The first negative electrode active material layer 22 may include a binder such that the negative electrode active material and the fibrous carbonaceous material may be stably dispersed in the slurry. For example, when the slurry is applied to the negative electrode current collector 21 by screen printing, clogging of the screen (e.g., clogging caused by aggregation of the negative electrode active material) may be suppressed or reduced.

[0084] With respect to 100 parts by weight of the mixture of the first negative electrode active material and the second negative electrode active material, the content (e.g., amount) of the binder may be in the range of about 0.1 part by weight to about 20 parts by weight, about 0.1 part by weight to about 15 parts by weight, about 1 part by weight to about 10 parts by weight, or about 5 parts by weight to about 10 parts by weight. The content (e.g., amount) of the binder may be in such a range, and thus the cycle characteristics of the all-solid-state secondary battery 1 may be further improved.

[0085] Negative electrode layer: Other additives In one or more embodiments, the first negative electrode active material layer 22 may further include one or more additives used in the all-solid-state secondary battery 1 according to the related art, such as fillers, coating agents, dispersants, and conductive aids.

[0086] Negative electrode layer: The first negative electrode active material layer The initial charge capacity (B) of the first negative electrode active material layer 22 may be, for example, 75% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the initial charge capacity (A) of the positive electrode active material layer 12.

[0087] In one or more embodiments, the ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer 12 can be, for example, in the range of about 0.01 to about 0.75, about 0.01 to about 0.7, about 0.01 to about 0.6, about 0.01 to about 0.5, about 0.01 to about 0.4, about 0.01 to about 0.3, about 0.01 to about 0.2, or about 0.01 to about 0.1. In one or more embodiments, the ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer 12 can be, for example, in the range of about 0.05 to about 0.75, about 0.1 to about 0.7, about 0.1 to about 0.6, about 0.2 to about 0.6, about 0.2 to about 0.5, or about 0.2 to about 0.45. The initial charge capacity of the positive electrode active material layer 12 can be determined by charging from the first OCV to the maximum charge voltage vs. Li / Li + to determine. The initial charge capacity of the first negative electrode active material layer 22 can be determined by charging from the second OCV to a voltage of about 0.01 V vs. Li / Li + to determine. The maximum charge voltage can be determined according to the type (species) of the positive electrode active material. The maximum charge voltage can be, for example, a voltage of about 1.5 V, about 2.0 V, about 2.5 V, about 3.0 V, about 3.5 V, about 4.0 V, about 4.2 V, or about 4.3 V. For example, in one or more embodiments, the maximum charge voltage of Li2S or a Li2S composite can be determined to be between about 2.5 V and about 3.0 V vs. Li / Li + . For example, in one or more embodiments, the maximum charge voltage of a lithium transition metal oxide can be determined to be between about 3.0 V and about 4.5 V vs. Li / Li + .

[0088] The initial charge capacity (mAh) of the positive electrode active material layer 12 can be obtained by multiplying the specific charge capacity (mAh / g) of the positive electrode active material by the mass (g) of the positive electrode active material in the positive electrode active material layer 12. When using one or more suitable types (kinds) of positive electrode active materials, for example, the value of the specific charge capacity × mass of each positive electrode active material can be calculated, and the sum of these values can be the initial charge capacity of the positive electrode active material layer 12. The initial charge capacity of the first negative electrode active material layer 22 can also be calculated in substantially the same manner. The initial charge capacity of the first negative electrode active material layer 22 can be obtained by multiplying the specific charge capacity (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the first negative electrode active material layer 22. When using one or more suitable types (kinds) of negative electrode active materials, for example, the value of the specific charge capacity × mass of each negative electrode active material can be calculated, and the sum of these values can be the initial charge capacity of the first negative electrode active material layer 22. The specific charge capacity of each of the positive electrode active material and the negative electrode active material can be measured by using a solid-state half-cell with lithium metal as the counter electrode. The initial charge capacity of each of the positive electrode active material layer 12 and the first negative electrode active material layer 22 can be directly measured by using a all-solid-state half-cell at a constant current density (for example, about 0.1 mA / cm 2 ) The measurement of the positive electrode can be performed at an operating voltage from the first OCV until the maximum charge voltage, for example, about 3.0 V (vs. Li / Li + ). The measurement of the negative electrode can be performed at an operating voltage from the second OCV until a voltage of about 0.01 V of the negative electrode (for example, lithium metal). For example, in one or more embodiments, the all-solid-state half-cell including the positive electrode active material layer 12 can be charged from the first OCV to a voltage of about 3.0 V at a constant current of 0.1 mA / cm 2 . The all-solid-state half-cell including the first negative electrode active material layer 22 can be charged from the second OCV to a voltage of about 0.01 V at a constant current of 0.1 mA / cm 2 . The current density during the constant current charging can be, for example, about 0.2 mA / cm 2 or about 0.5 mA / cm 2 . In one or more embodiments, the all-solid-state half-cell including the positive electrode active material layer 12 can be charged, for example, from the first OCV to a voltage of about 2.5 V, about 3.0 V, about 3.5 V, about 4.0 V, or 4.5 V. The maximum charge voltage of the positive electrode active material layer can be determined by the maximum voltage of a battery that satisfies the safety conditions of JIS C 8712:2015 of the Japanese Standards Association.

[0089] When the initial charge capacity of the first negative electrode active material layer 22 is excessively (or significantly) low, for example, the first negative electrode active material layer 22 may become very thin. Therefore, during repeated charge / discharge processes, lithium dendrites formed between the first negative electrode active material layer 22 and the negative electrode current collector 21 may cause the first negative electrode active material layer 22 to collapse, which may make it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the charge capacity of the first negative electrode active material layer 22 is excessively (or significantly) increased, for example, the energy density of the all-solid-state secondary battery 1 may decrease, and the internal resistance of the all-solid-state secondary battery 1 caused by the first negative electrode active material layer 22 may increase, which may make it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1.

[0090] The thickness of the first negative electrode active material layer 22 may be, 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. In one or more embodiments, the thickness of the first negative electrode active material layer 22 may be, for example, in the range of about 1% to about 50%, about 1% to about 40%, about 1% to about 30%, about 1% to about 20%, or about 1% to about 10% of the thickness of the positive electrode active material layer 12. In one or more embodiments, the thickness of the first negative electrode active material layer 22 may be, for example, in the range of about 1 μm to about 50 μm, about 2 μm to about 40 μm, about 3 μm to about 30 μm, about 4 μm to about 20 μm, or about 5 μm to about 20 μm. In one or more embodiments, the thickness of the first negative electrode active material layer 22 may be, for example, in the range of about 5 μm to about 50 μm, about 10 μm to about 50 μm, about 15 μm to about 50 μm, about 20 μm to about 50 μm, or about 25 μm to about 50 μm. When the first negative electrode active material layer 22 is too thin (or significantly thin), for example, lithium dendrites formed between the first negative electrode active material layer 22 and the negative electrode current collector 21 may cause the first negative electrode active material layer 22 to collapse, which may make it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the thickness of the first negative electrode active material layer 22 is excessively (or significantly) increased, the energy density of the all-solid-state secondary battery 1 may decrease, and the internal resistance of the all-solid-state secondary battery 1 caused by the first negative electrode active material layer 22 may increase, which may make it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the thickness of the first negative electrode active material layer 22 decreases, for example, the initial charge capacity of the first negative electrode active material layer 22 may also decrease.

[0091] Negative electrode layer: Second negative electrode active material layer Refer to Figure 3, in one or more embodiments, the all-solid-state secondary battery 1 may further include: a second negative electrode active material layer 24 disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 after charging. In one or more embodiments, the second negative electrode active material layer 24 may be disposed between the negative electrode current collector 21 and the solid electrolyte layer 30. The second negative electrode active material layer 24 may be a metal layer containing lithium or a lithium alloy. The metal layer may include lithium or a lithium alloy. In one or more embodiments, the second negative electrode active material layer 24 may be a metal layer containing lithium and thus may be used as, for example, a lithium reservoir. Examples of the lithium alloy may include 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 the embodiments of the present disclosure are not limited thereto. Any material may be used as long as the material can be used as a lithium alloy in the art. The second negative electrode active material layer 24 may include one such alloy or lithium (e.g., consist of one such alloy or lithium), or may include one or more suitable types (kinds) of alloys (e.g., consist of one or more suitable types (kinds) of alloys). In one or more embodiments, the second negative electrode active material layer 24 may be, for example, a plating layer. For example, during the charging process of the all-solid-state secondary battery 1, the second negative electrode active material layer 24 may precipitate between the first negative electrode active material layer 22 and the negative electrode current collector 21.

[0092] The thickness of the second negative electrode active material layer 24 is not limited, but may be, for example, in the range of about 1 μm to about 200 μm, about 1 μm to about 150 μm, about 1 μm to about 100 μm, about 1 μm to about 50 μm, about 1 μm to about 30 μm, about 1 μm to about 22 μm, or about 1 μm to about 10 μm. When (e.g., if) the second negative electrode active material layer 24 is too thin (or significantly thin), it is difficult for the second negative electrode active material layer 24 to be used as a lithium reservoir. When (e.g., if) the second negative electrode active material layer 24 is too thick (or significantly thick), the mass and volume of the all-solid-state secondary battery 1 may increase, and the cycle characteristics of the all-solid-state secondary battery 1 may be actually deteriorated.

[0093] For example, in one or more embodiments, the thickness of the second negative electrode active material layer 24 may be less than the thickness of the first negative electrode active material layer 22. The thickness of the second negative electrode active material layer 24 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 first negative electrode active material layer 22. In one or more embodiments, the thickness of the second negative electrode active material layer 24 may be, for example, in the range of about 1% to about 70%, about 1% to about 60%, about 1% to about 50%, about 1% to about 40%, or about 1% to about 30% of the thickness of the first negative electrode active material layer 22. The thickness of the second negative electrode active material layer 24 may be less than the thickness of the first negative electrode active material layer 22, and thus volume change during charging or discharging of the all-solid-state secondary battery 1 can be suppressed or reduced. In one or more embodiments, deterioration caused by volume change of the all-solid-state secondary battery 1 can be suppressed or reduced.

[0094] In one or more embodiments, in the all-solid-state secondary battery 1, for example, before assembling the all-solid-state secondary battery 1, the second negative electrode active material layer 24 may be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22. When (for example, when) the second negative electrode active material layer 24 is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all-solid-state secondary battery 1, the second negative electrode active material layer 24 may be a metal layer containing lithium, and thus can be used as a lithium reservoir. For example, in some embodiments, a lithium foil may be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all-solid-state secondary battery 1.

[0095] When, for example, the second negative electrode active material layer 24 is deposited by charging the all-solid-state secondary battery 1 after assembly, the all-solid-state secondary battery 1 may not include (e.g., may exclude) the second negative electrode active material layer 24 during the assembly of the all-solid-state secondary battery 1, and thus the energy density of the all-solid-state secondary battery 1 can be increased. During the charging of the all-solid-state secondary battery 1, the first negative electrode active material layer 22 can be charged beyond its charging capacity. For example, the first negative electrode active material layer 22 can be overcharged. At the start of charging, lithium can be intercalated into the first negative electrode active material layer 22. The negative electrode active material included in the first negative electrode active material layer 22 can form an alloy or a compound with the lithium ions that move / migrate from the positive electrode layer 10. When, for example, charging is carried out beyond the capacity of the first negative electrode active material layer 22, lithium can be deposited, for example, on the rear side of the first negative electrode active material layer 22 (e.g., between the negative electrode current collector 21 and the first negative electrode active material layer 22), and the metal layer corresponding to the second negative electrode active material layer 24 can be formed by the deposited lithium. The second negative electrode active material layer 24 can be a metal layer mainly composed of lithium (e.g., metallic lithium) (e.g., consisting of lithium (e.g., metallic lithium)). For example, such a result is obtained because the negative electrode active material included in the first negative electrode active material layer 22 includes a material that forms an alloy or a compound with lithium. During discharging, the lithium in the first negative electrode active material layer 22 and the second negative electrode active material layer 24 (e.g., the lithium in the metal layer) can be ionized to move toward the positive electrode layer 10. In one or more embodiments, in the all-solid-state secondary battery 1, lithium can be used as the negative electrode active material. In one or more embodiments, the first negative electrode active material layer 22 can cover the second negative electrode active material layer 24, thereby serving as a protective layer for the second negative electrode active material layer 24 (e.g., the metal layer) and, for example, simultaneously suppressing or reducing the growth of lithium dendrite deposition. In one or more embodiments, the short circuit and capacity reduction of the all-solid-state secondary battery 1 can be suppressed or reduced, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In one or more embodiments, when, for example, the second negative electrode active material layer 24 is provided by charging the all-solid-state secondary battery 1 after assembly, the negative electrode layer 20 (e.g., the negative electrode current collector 21, the first negative electrode active material layer 22, and the region between the negative electrode current collector 21 and the first negative electrode active material layer 22) can be a Li-free region that does not include lithium (Li) in the initial state of the all-solid-state secondary battery 1 or in the state after its full discharge.

[0096] Negative electrode layer: Negative electrode current collector The negative electrode current collector 21 may include a material that does not react with lithium (e.g., consisting of a material that does not react with lithium), e.g., a material that does not form both an alloy and a compound with lithium (e.g., does not form an alloy and a compound with lithium simultaneously). Examples of materials constituting the negative electrode current collector 21 may include copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but the embodiments of the present disclosure are not necessarily limited thereto. Any material may be used as long as it can be used as a negative electrode current collector in the art. The negative electrode current collector 21 may include one type (or kind) of the above metals, an alloy of two or more types (kinds) of the above metals, or a coating material (e.g., consisting of them). The negative electrode current collector 21 may be in the form of, for example, a plate or a foil.

[0097] Referring Figure 2 , in one or more embodiments, the all-solid-state secondary battery 1 may further include a thin film 23 on one side (or one surface) (e.g., one side (or one surface)) of the negative electrode current collector 21. The thin film 23 includes an element capable of forming an alloy with lithium. The thin film 23 may be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22. The thin film 23 may include, for example, an element capable of forming an alloy with lithium. Examples of elements capable of forming an alloy with lithium may include gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but the embodiments of the present disclosure are not necessarily limited thereto. Any material may be used as long as it can form an alloy with lithium in the art. The thin film 23 may include one such metal or an alloy of one or more suitable types (kinds) of such metals (e.g., consisting of one such metal or an alloy of one or more suitable types (kinds) of such metals). The thin film 23 may be disposed on one side (or one surface) (e.g., one side (or one surface)) of the negative electrode current collector 21 such that, for example, the precipitation form of the second negative electrode active material layer 24 precipitated between the thin film 23 and the first negative electrode active material layer 22 can be further flattened, and the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

[0098] The thickness of the thin film 23 may be, for example, in the range of about 1 nm to about 800 nm, about 10 nm to about 700 nm, about 50 nm to about 600 nm, or about 100 nm to about 500 nm. When the thickness of the thin film 23 is less than 1 nm, it may be difficult for the thin film 23 to function. When the film 23 is too thick (or significantly thick), the thin film 23 itself may adsorb lithium, so the amount of lithium precipitation in the negative electrode layer 20 may be reduced, resulting in a decrease in the energy density of the all-solid-state secondary battery 1 and deterioration of the cycle characteristics of the all-solid-state secondary battery 1. The thin film 23 may be disposed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, electroplating, etc., but the embodiments of the present disclosure are not necessarily limited to such methods. Any method capable of forming the thin film 23 in the art may be used.

[0099] In one or more embodiments, the negative electrode current collector 21 may include, for example, a base film and a metal layer disposed on one side (or one surface) of the base film (e.g., one side (or one surface) or two opposite sides (or two opposite surfaces)). 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), PE, polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), and / or a (e.g., any suitable) combination thereof. The polymer may be an insulating polymer. In one or more embodiments, the base film may include an insulating thermoplastic polymer, so that, when (e.g., in the event of) a short circuit occurs, the base film may soften or liquefy to interrupt the operation of the battery, thereby suppressing or reducing a rapid 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. In one or more embodiments, the negative electrode current collector 21 may additionally include a metal sheet and / or a lead tab. The base film, metal layer, metal sheet, and lead tab of the negative electrode current collector 21 may be further referred to the positive electrode current collector 11 described later. The negative electrode current collector 21 may have such a structure, so that the weight of the negative electrode layer 20 can be reduced, thereby improving the energy density of the negative electrode layer 20 and the all-solid-state secondary battery 1.

[0100] Negative electrode layer: First inert member Refer to Figure 4 and Figure 5 and Figures 8 to 12 , in one or more embodiments, the all-solid-state secondary battery 1 may further include a first inert member 40 (40a and / or 40b) disposed on at least one of the other side of the negative electrode current collector 21 (i.e., the side facing away from the negative electrode active material layer 22) and the other surface of the positive electrode current collector 11 (i.e., the side facing away from the positive electrode active material layer 12).

[0101] In one or more embodiments, the first inert member 40 (40a and / or 40b) may not include (e.g., may exclude) an electrode active material. The first inert member 40 (40a and / or 40b) may be, for example, an insulating member.

[0102] In one or more embodiments, the first inert member 40 (40a and / or 40b) may additionally include a conductive material (e.g., an electronic conductor) to have conductivity. In one or more embodiments, the first inert member 40 (40a and / or 40b) may additionally include a flame retardant material, so that it may be, for example, a flame retardant inert member.

[0103] In one or more embodiments, the first inert member 40 (40a and / or 40b) may be, for example, an elastic member. The first inert member 40 (40a and / or 40b) may be, for example, a porous elastic member. In one or more embodiments, the first inert member 40 (40a and / or 40b) may be an elastic member having at least one of porosity, conductivity, and flame retardancy.

[0104] The first inert member 40 (40a and / or 40b) may impart a buffering function to the all-solid-state secondary battery 1. The first inert member 40 (40a and / or 40b) may provide, for example, stress relaxation and restoring force. The first inert member 40 (40a and / or 40b) may effectively accommodate the volume change of the all-solid-state secondary battery 1 and may apply a certain pressure to the all-solid-state secondary battery 1.

[0105] For example, in one or more embodiments, the first inert member 40 (40a and / or 40b) may have an elastic modulus lower than that of the negative electrode current collector 21. The first inert member 40 (40a and / or 40b) may have an elastic modulus lower than that of the negative electrode current collector 21, and thus may more effectively accommodate the volume change of the negative electrode layer 20 during charging / discharging of the all-solid-state secondary battery 1. The first inert member 40 may effectively relieve the internal stress caused by the volume change of the all-solid-state secondary battery 1 during charging / discharging, thereby improving the cycle characteristics of the all-solid-state secondary battery 1.

[0106] In one or more embodiments, the first inert member 40 (40a and / or 40b) may be disposed, for example, on the negative electrode layer 20 of the all-solid-state secondary battery 1. When (for example, when) the volume change of the negative electrode layer 20 is relatively larger than that of the positive electrode layer 10 and the solid electrolyte layer 30 during charging or discharging of the all-solid-state secondary battery 1, the first inert member 40 (40a and / or 40b) may be disposed adjacent to the negative electrode layer 20 so as to more effectively accommodate the volume change of the negative electrode layer 20. In one or more embodiments, the first inert member 40 (40a and / or 40b) may apply a certain pressure to the negative electrode layer 20 to cause, for example, substantially uniform precipitation of lithium metal in the negative electrode layer 20. In one or more embodiments, defects generated in the all-solid-state secondary battery 1 due to non-substantially uniform precipitation of lithium metal may be more effectively prevented or reduced.

[0107] In one or more embodiments, the first inert member 40 (40a and / or 40b) may be disposed, for example, on the positive electrode layer 10 of the all-solid-state secondary battery 1. The first inert member 40 (40a and / or 40b) may be disposed adjacent to the positive electrode layer 10 so as to more effectively accommodate the volume change of the all-solid-state secondary battery 1. In one or more embodiments, the first inert member 40 (40a and / or 40b) may apply a certain pressure to the all-solid-state secondary battery 1 to cause, for example, substantially uniform precipitation of lithium metal in the negative electrode layer 20. In one or more embodiments, defects generated in the all-solid-state secondary battery 1 due to non-substantially uniform precipitation of lithium metal can be more effectively prevented or reduced.

[0108] In one or more embodiments, the first inert member 40 (40a and / or 40b) may include a polymeric material, a rubber material, and / or a combination thereof (e.g., any suitable combination). The first inert member 40 (40a or 40b) may include a polymeric material, a rubber material, or a combination thereof, and thus may have stress relaxation and resilience. The polymeric material may include, for example, polyurethane polymers, polyacrylate polymers, polystyrene polymers, polyester polymers, polyamide polymers, polyolefin polymers, and / or any suitable combination thereof. In some embodiments, the polymeric material may be, for example, a polymeric resin. In some embodiments, the polymeric material may be, for example, an adhesive resin. The rubber material may include, for example, natural rubber (NR), butadiene rubber (BR), nitrile rubber, silicone rubber, isoprene rubber (IR), styrene-butadiene rubber (SBR), isoprene-butadiene rubber, styrene-isoprene-butadiene rubber, acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber, halogenated butyl rubber, chloroprene rubber (CR), halogenated isoprene rubber, halogenated isobutene copolymer, chloroprene rubber, butyl rubber (IIR), halogenated isobutene-p-methylstyrene rubber, and / or any suitable combination thereof. The polyurethane polymers may include, for example, polyester polyurethanes, polyether polyurethanes, and / or any suitable combination thereof. The polyacrylate polymers may include, for example, polyacrylates, polymethyl acrylates, polymethacrylates, polymethyl methacrylates, and / or any suitable combination thereof. The polystyrene polymers may include, for example, styrene-ethylene-butene (SEB) copolymers, styrene-butadiene-styrene (SBS) copolymers, hydrogenated products of SBS (styrene-ethylene-butene-styrene (SEBS) copolymers), styrene-isoprene-styrene (SIS) copolymers, hydrogenated products of SIS (styrene-ethylene-propylene-styrene (SEPS) copolymers), styrene-isobutene-styrene (SIBS) copolymers, styrene-butadiene-styrene-butadiene (SBSB) copolymers, styrene-butadiene-styrene-butadiene-styrene (SBSBS) copolymers, polystyrene (PS), acrylonitrile-styrene (AS) copolymers, acrylonitrile-butadiene-styrene (ABS) copolymers, and / or any suitable combination thereof. The polyester polymers may include, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and / or any suitable combination thereof. The polyamide polymers may include, for example, polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, and / or any suitable combination thereof.Polyolefin polymers can include, for example, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, propylene-1-hexene copolymer, propylene-4-methyl-1-pentene copolymer, propylene-1-butene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-pentene copolymer, ethylene-1-butene copolymer, 1-butene-1-hexene copolymer, 1-butene-4-methyl-pentene copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl methacrylate copolymer, ethylene-butyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, propylene-methacrylate copolymer, propylene-methyl methacrylate copolymer, propylene-ethyl methacrylate copolymer, propylene-butyl methacrylate copolymer, propylene-methyl acrylate copolymer, propylene-ethyl acrylate copolymer, propylene-butyl acrylate copolymer, ethylene-vinyl acetate copolymer (EVA), polyolefins of propylene-vinyl acetate copolymer, and / or their (e.g., any suitable) combination.

[0109] In one or more embodiments, the first inert member 40 (40a and / or 40b) can include, for example, porous foam, porous sponge, and / or their (e.g., any suitable) combination. The first inert member 40 (40a and / or 40b) can include, for example, a porous foam sheet, a porous sponge sheet, and / or their (e.g., any suitable) combination. The first inert member 40 (40a and / or 40b) can be in such a form that it can provide both porosity and a buffering function simultaneously. The porous foam can include, for example, closed cells, open cells, and / or their (e.g., any suitable) combination. The porous sponge can include, for example, closed cells, open cells, and / or their (e.g., any suitable) combination. The closed cell can be, for example, a closed pore and can refer to an orifice or pore that is not in communication with the surrounding atmosphere. The open cell can be an open pore and can refer to an orifice or pore that is in communication with the surrounding atmosphere. The first inert member 40 (40a or 40b) can include, for example, closed-cell porous foam, open-cell porous foam, closed-cell porous sponge, open-cell porous sponge, and / or their (e.g., any suitable) combination. The porous foam can, for example (e.g., simultaneously), include both closed and open cells. The porous sponge can, for example (e.g., simultaneously), include both closed and open cells.

[0110] In one or more embodiments, the first inert member 40 (40a and / or 40b) may include, for example, a conductive material (e.g., an electronic conductor). Non-limiting examples of the conductive material may include graphite, CB, AB, KB, Denkablack, carbon fiber, CNT, graphene, metal fiber, metal powder, and the like. With respect to 100 parts by weight of the first inert member 40 (40a and / or 40b), the content (e.g., amount) of the conductive material included in the first inert member 40 (40a and / or 40b) may be, for example, in the range of about 1 part by weight to about 40 parts by weight, about 1 part by weight to about 30 parts by weight, about 1 part by weight to about 20 parts by weight, about 1 part by weight to about 15 parts by weight, about 5 parts by weight to about 40 parts by weight, about 5 parts by weight to about 30 parts by weight, or about 5 parts by weight to about 35 parts by weight. The first inert member 40 may have conductivity and thus can be used as the negative electrode current collector 21.

[0111] In one or more embodiments, the first inert member 40 (40a and / or 40b) may include, for example, a matrix and a filler. In one or more embodiments, the matrix may include, for example, a base material and a reinforcing material. In some embodiments, the matrix may include, for example, a fibrous base material and a fibrous reinforcing material. The matrix may include a fibrous base material to have elasticity. The fibrous base material may include, for example, at least one selected from pulp fibers, insulating polymer fibers, and ion-conductive polymer fibers. The matrix may include a reinforcing material and thus can improve the strength of the matrix. The fibrous reinforcing material may include, for example, glass fiber, metal oxide fiber, and / or ceramic fiber. In some embodiments, the fibrous reinforcing material may be, for example, a flame retardant material. In one or more embodiments, the filler may include, for example, a moisture absorbent and / or a flame retardant. The filler may include, for example, a metal hydroxide having moisture adsorption properties. The metal hydroxide included in the filler may be, for example, Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, TI(OH)3, Zr(OH)4, Al(OH)3, and / or their (e.g., any suitable) combination.

[0112] In one or more embodiments, the first inert member 40 (40a and / or 40b) may be, for example, thicker than the first negative electrode active material layer 22. The first inert member 40 (40a and / or 40b) may be thicker than the first negative electrode active material layer 22, and thus may more effectively accommodate the volume change of the negative electrode layer 20 during charging or discharging. The thickness of the first negative electrode active material layer 22 may be 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the first inert member 40 (40a and / or 40b). In one or more embodiments, the thickness of the first negative electrode active material layer 22 may be, for example, in the range of about 1% to about 50%, about 1% to about 40%, about 1% to about 30%, about 1% to about 20%, or about 1% to about 10% of the thickness of the first inert member 40 (40a and / or 40b). In one or more embodiments, the thickness of the first inert member 40 (40a and / or 40b) may be, for example, in the range of about 10 μm to about 300 μm, about 20 μm to about 300 μm, about 50 μm to about 300 μm, or about 100 μm to about 200 μm. When the first inert member 40 (40a and / or 40b) is too thin (or significantly thin), it may be difficult to provide the desired effect, and when the first inert member 40 (40a and / or 40b) is too thick (or significantly thick), the energy density of the all-solid-state secondary battery 1 may decrease. The form of the first inert member 40 (40a and / or 40b) is not limited and may be selected according to the form of the all-solid-state secondary battery 1. The first inert member 40 (40a and / or 40b) may be in the form of, for example, a sheet, a rod, or a washer. For example, in some embodiments, the first inert member 40 (40a and / or 40b) may not be provided.

[0113] Positive electrode layer Positive electrode layer: Positive electrode active material Refer to Figures 1 to 12 , the positive electrode active material layer 12 may include, for example, a positive electrode active material.

[0114] The positive electrode active material included in the positive electrode active material layer 12 may be a positive electrode active material that can reversibly intercalate and deintercalate lithium ions. The positive electrode active material may include, for example, oxide-based positive electrode active materials (e.g., in the form of particles), sulfide-based positive electrode active materials (e.g., in the form of particles), and / or any suitable combination thereof.

[0115] Oxide-based cathode active materials may include, for example, lithium transition metal oxides, lithium-free metal oxides, and / or combinations thereof (e.g., any suitable combination). Lithium transition metal oxides may include, for example, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, lithium iron phosphate, and / or combinations thereof (e.g., any suitable combination). Lithium-free metal oxides may include, for example, iron oxide, vanadium oxide, and / or combinations thereof (e.g., any suitable combination).

[0116] Sulfide-based cathode active materials may include, for example, nickel sulfide, copper sulfide, Li2S, Li2S-containing complexes, and / or combinations thereof (e.g., any suitable combination).

[0117] In one or more embodiments, the oxide-based cathode active material may include, for example, at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and / or combinations thereof (e.g., any suitable combination). The lithium-containing oxide-based cathode active material may include, for example, a compound represented by at least one of the following formulas: Li a A 1-b B' b D2 (where 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.0); LiE 2-b B' b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Lia Ni 1-b-c Mn b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni b E c G d O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1, and 0.001 ≤ b ≤ 0.1); LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3 (where 0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2); and LiFePO4.

[0118] In the formula representing the above compound, A can be nickel (Ni), cobalt (Co), manganese (Mn) and / or a combination thereof (e.g., any suitable combination), B' can be Al, Ni, Co, Mn, chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), rare earth elements and / or a combination thereof (e.g., any suitable combination), D can be oxygen (O), fluorine (F), sulfur (S), phosphorus (P) and / or a combination thereof (e.g., any suitable combination), E can be Co, Mn and / or a combination thereof (e.g., any suitable combination), F' can be F, S, P and / or a combination thereof (e.g., any suitable combination), G can be Al, Cr, Mn, Fe, Mg, lanthanum (La), cerium (Ce), Sr, V and / or a combination thereof (e.g., any suitable combination), Q can be Ti, Mo, Mn and / or a combination thereof (e.g., any suitable combination), I' can be Cr, V, Fe, scandium (Sc), yttrium (Y) and / or a combination thereof (e.g., any suitable combination), and J can be V, Cr, Mn, Co, Ni, Cu and / or a combination thereof (e.g., any suitable combination). In one or more embodiments, a compound in which a coating is added to the surface of the above compound can also be used, and / or a mixture of two or more of the above compounds (e.g., any suitable combination) and a compound in which a coating is added thereto can also be used. The coating added to the surface of the above compound can include, for example, a coated element compound: an oxide or hydroxide of the coated element, a hydroxyoxide of the coated element, a carbonate oxide of the coated element, and / or a hydroxycarbonate of the coated element. The compound constituting the coating can be amorphous or crystalline. The coated elements included in the coating can include Mg, Al, Co, potassium (K), sodium (Na), calcium (Ca), silicon (Si), Ti, V, Sn, germanium (Ge), gallium (Ga), boron (B), arsenic (As), zirconium (Zr) and / or a mixture thereof (e.g., any suitable combination). The method of forming the coating can be selected within a method that does not adversely affect the physical properties of the positive electrode active material. For example, the coating method can include spraying, dipping, etc. Those skilled in the art can well understand these coating methods, and thus a detailed description thereof will not be provided.

[0119] In one or more embodiments, the oxide-based positive electrode active material can include, for example, one or more selected from among lithium transition metal oxides represented by Formula 1 to Formula 8: Formula 1 Li a Ni x Co y M z O 2-b A b In Formula 1, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.8 ≤ x < 1, 0 ≤ y ≤ 0.3, 0 < z ≤ 0.3, x + y + z = 1, M can be 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 (e.g., any suitable combination), and A can be F, S, Cl, Br or a combination thereof (e.g., any suitable combination). Formula 2 LiNi x Co y Mn z O2 Formula 3 LiNi x Co y Al z O2 In Formulas 2 and 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1. Formula 4 LiNi x Co y Mn z Al w O2 In Formula 4, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, 0 < w ≤ 0.2, and x + y + z + w = 1. Formula 5 Li a Co x M y O 2-b A b In Formula 5, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, x + y = 1, M can be 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 (e.g., any suitable combination), and A can be F, S, Cl, Br or a combination thereof (e.g., any suitable combination). Formula 6 Li a Ni x Mn y M' z O 2-b A b In Formula 6, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, x + y + z = 1, M' can be 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 (e.g., any suitable combination), and A can be F, S, Cl, Br or a combination thereof (e.g., any suitable combination). Formula 7 Li a M1 x M2 y PO 4-b X b In Formula 7, 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, 0 ≤ b ≤ 2, M1 can be chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof (e.g., any suitable combination), M2 can be 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 (e.g., any suitable combination). X can be O, F, S, P or a combination thereof (e.g., any suitable combination), and Formula 8 Li a M3 z PO4 In Formula 8, 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1, and M3 can be chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof (e.g., any suitable combination).

[0120] In one or more embodiments, the oxide-based positive electrode active material can be covered with a coating. As the coating, any coating can be used as long as the coating is suitable as a coating for the positive electrode active material of the all-solid-state secondary battery. In one or more embodiments, the coating can include, for example, Li2O-ZrO2 (LZO).

[0121] The size of the oxide-based positive electrode active material can be, for example, in the range of about 0.1 μm to about 30 μm, about 0.5 μm to about 20 μm, or about 1 μm to about 15 μm. The oxide-based positive electrode active material can include, for example, single crystal particles or polycrystalline particles.

[0122] The sulfide-based positive electrode active material can include, for example, a complex containing Li2S. The complex containing Li2S can include, for example, a complex of Li2S and a conductive material, a complex of Li2S, a solid electrolyte, and a conductive material, a complex of Li2S and a solid electrolyte, a complex of Li2S and a lithium salt, a complex of Li2S, a lithium salt, and a conductive material, a complex of Li2S and a metal carbide, a complex of Li2S, a metal carbide, and a conductive material, a complex of Li2S and a metal nitride, a complex of Li2S, a metal nitride, and a conductive material, and / or their (e.g., any suitable) combination. The complex containing Li2S can be different from a simple mixture of Li2S, a conductive material, a solid electrolyte, a lithium salt, a metal carbide, and / or a metal nitride. A simple mixture of Li2S, a conductive material, a solid electrolyte, a lithium salt, a metal carbide, and / or a metal nitride may provide a high interfacial resistance because it may not be able to maintain a dense interface between Li2S and these other components, and thus may deteriorate the life characteristics of the all-solid-state secondary battery.

[0123] The complex containing Li2S can include Li2S. Li2S can have a high theoretical capacity and thus can provide a secondary battery with a high energy density. However, in order to overcome disadvantages such as low ionic conductivity and / or electron conductivity, Li2S can form a complex with a lithium salt, a metal halide, a conductive material, etc. The content (e.g., amount) of Li2S in the complex containing Li2S can be, for example, in the range of about 10 wt% to about 80 wt%, about 20 wt% to about 80 wt%, about 30 wt% to about 80 wt%, or about 40 wt% to about 80 wt% with respect to the total weight of 100 wt% of the complex containing Li2S. When the content (e.g., amount) of Li2S in the complex containing Li2S is excessively (or significantly) increased, it may not be easy to improve the ionic conductivity and / or electron conductivity of the complex containing Li2S. When the content (e.g., amount) of Li2S in the complex containing Li2S is too low (or significantly low), the energy density of the all-solid-state secondary battery may decrease.

[0124] In addition to Li2S, the composite of Li2S and a conductive material may further include a conductive material. The conductive material may include, for example, carbonaceous materials. As carbonaceous materials, for example, any material may be used as long as the material may be a material including carbon atoms and may be used as a conductive material (e.g., an electronic conductor) in the art. The carbonaceous material may be, for example, a crystalline carbonaceous material, an amorphous carbonaceous material, or a combination thereof (e.g., any suitable combination). The carbonaceous material may be, for example, a sintered material of a carbon precursor. In one or more embodiments, the carbonaceous material may include, for example, carbon nanostructures. The carbon nanostructures may include, for example, one-dimensional carbon nanostructures, two-dimensional carbon nanostructures, three-dimensional carbon nanostructures, and / or a combination thereof (e.g., any suitable combination). The carbon nanostructures may include, for example, CNT, CNF, carbon nanotapes, carbon nanorods, graphene, graphene oxide (GO), reduced graphene oxide (rGO), graphene balls (GB), and / or a combination thereof (e.g., any suitable combination). In one or more embodiments, the carbonaceous material may be, for example, a porous carbonaceous material or a non-porous carbonaceous material. The porous carbonaceous material may include, for example, periodic and regular two-dimensional pores or three-dimensional pores. The porous carbonaceous material may include, for example: CB, such as KB, AB, Denka black, thermal black, and / or channel black; graphite; activated carbon; and / or a combination thereof (e.g., any suitable combination). The form of the carbonaceous material may be, for example, a particulate form (e.g., in particulate form), a sheet form (e.g., in sheet form), a fibrous form (e.g., in fibrous form), etc., but the embodiments of the present disclosure are not limited thereto. Any material may be used as long as the material may be used as a carbonaceous material in the art. The method for preparing the composite of Li2S and the carbonaceous material may be a dry method, a wet method, or a combination thereof (e.g., any suitable combination), but the embodiments of the present disclosure are not limited thereto. The method for preparing the composite of Li2S and the carbonaceous material may include, for example, grinding, heat treatment, deposition, etc., but the embodiments of the present disclosure are not necessarily limited thereto. Any method may be used as long as the method may be used.

[0125] In addition to Li2S, the composite of Li2S, a solid electrolyte, and a conductive material may further include a conductive material and a solid electrolyte. The conductive material may include, for example, carbon-based materials. The carbon-based materials may be defined as the above-mentioned carbon-based materials used in the composite of Li2S and the conductive material. The solid electrolyte may be, for example, an amorphous solid electrolyte, and any material may be used as long as it can be used as an ion-conductive material in the art. In one or more embodiments, the solid electrolyte may be, for example, an inorganic solid electrolyte. In one or more embodiments, the solid electrolyte may be, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, and / or their (e.g., any suitable) combination. In one or more embodiments, the solid electrolyte may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and / or their (e.g., any suitable) combination. The sulfide-based solid electrolyte may include, for example, Li, S, and P, and may optionally further include a halogen element. The sulfide-based solid electrolyte may be selected from the sulfide-based solid electrolytes used in the solid electrolyte layer. For example, the sulfide-based solid electrolyte may have an ionic conductivity of 1×10 -5 S / cm or greater at room temperature. The sulfide-based solid electrolyte may include, for example, those selected from Li3PO4-Li2SO4, 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 (where both m and n are positive numbers, and Z may be one selected from Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where both p and q are positive numbers, and M may be one selected from P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2), and Li 7-x PS 6-x I xAt least one of (where 0 ≤ x ≤ 2). The oxide-based solid electrolyte may include, for example, Li, O, and transition metal elements, and may optionally further include other elements. For example, the oxide-based solid electrolyte may be a solid electrolyte having an ionic conductivity of 1×10 -5 S / cm or greater at room temperature. The oxide-based solid electrolyte may be selected from oxide-based solid electrolytes used in the solid electrolyte layer. In one or more embodiments, the solid electrolyte may include, for example, a mixture of a sulfide-based solid electrolyte and a lithium salt. For example, in one or more embodiments, the solid electrolyte may include a mixture of Li3PO4-Li2SO4 and a binary lithium salt and / or a mixture of Li3PO4-Li2SO4 and a ternary lithium salt.

[0126] In addition to Li2S, the composite of Li2S and the solid electrolyte may further include the solid electrolyte. The solid electrolyte may be defined as the above solid electrolyte used in the composite of Li2S, the conductive material, and the solid electrolyte.

[0127] The composite of Li2S, a lithium salt, and a conductive material may include Li2S, a lithium salt, and a conductive material. The conductive material may include, for example, carbonaceous materials. The carbonaceous materials may be defined for the composite of the above Li2S and the conductive material. The lithium salt may include, for example, lithium salt compounds. The lithium salt compounds may not include (e.g., may exclude) sulfur (S) atoms, for example. The lithium salt compounds may be, for example, binary compounds or ternary compounds. In one or more embodiments, the lithium salt compounds may be, for example, binary compounds containing lithium and one type (or species) of element selected from Group XIII to Group XVII of the periodic table. The binary compounds may include, for example, at least one selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3. In one or more embodiments, the lithium salt compounds may be, for example, ternary compounds containing lithium and two types (species) of elements selected from Group XIII to Group XVII of the periodic table. The ternary compounds may include, for example, at least one selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. In some embodiments, the lithium salt compounds may include at least one lithium halide compound selected from LiF, LiCl, LiBr, and LiI. The composite of Li2S, a lithium salt, and a conductive material may be, for example, a composite of Li2S, a lithium halide, and a carbonaceous material. The composite of Li2S, a lithium salt, and a carbonaceous material may include a lithium halide, and thus may provide further improved ionic conductivity. The composite of Li2S, a lithium salt, and a carbonaceous material may be different from a simple mixture of Li2S, a lithium salt, and a carbonaceous material. A simple mixture of Li2S, a lithium salt, and a carbonaceous material may provide a high interfacial resistance because it may not be able to maintain a dense interface between Li2S, a lithium salt, and a carbonaceous material, and thus may deteriorate the life characteristics of the all-solid-state secondary battery.

[0128] The composite of Li2S and a lithium salt may include Li2S and a lithium salt. The lithium salt may be defined as the above lithium salt for the composite of Li2S, a lithium salt, and a conductive material.

[0129] In addition to Li2S, the composite of Li2S and a metal carbide may further include a metal carbide. The metal carbide may be, for example, a two-dimensional metal carbide. The two-dimensional metal carbide may be, for example, Mxene. The two-dimensional metal carbide may be, for example, composed of M n+1 C n T xIt is represented that, where M can be a transition metal, T can be a terminal group, T can be O, OH, and / or F, n = 1, 2, or 3, and x is the number of terminal groups. The two-dimensional metal carbide can be, for example, Ti2CT x , (Ti 0.5 , Nb 0.5 )2CT x , Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5 )3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x or a combination thereof (e.g., any suitable combination). The surface of the two-dimensional metal carbide can be terminated with O, OH, and / or F, and the total number of O, OH, and / or F at the surface is the number of terminal groups.

[0130] The composite of Li2S, metal carbide, and conductive material can include Li2S, metal carbide, and conductive material. The conductive material can include, for example, carbonaceous materials. The carbonaceous materials can be defined as the above-mentioned carbonaceous materials used in the composite of Li2S and conductive material. The metal carbide can be defined as the above-mentioned metal carbide used in the composite of Li2S and metal carbide.

[0131] The composite of Li2S and metal nitride can include Li2S and metal nitride. The metal nitride can be, for example, a two-dimensional metal nitride. The two-dimensional metal nitride can be represented, for example, by M n+1 N n T x where M can be a transition metal, T can be a terminal group, T can be O, OH, and / or F, n = 1, 2, or 3, and x is the number of terminal groups. The surface of the two-dimensional metal nitride can be terminated with O, OH, and / or F, and the total number of O, OH, and / or F at the surface is the number of terminal groups.

[0132] The composite of Li2S, metal nitride, and conductive material can include Li2S, metal nitride, and conductive material. The conductive material can include, for example, carbonaceous materials. The carbonaceous materials can be defined as the above-mentioned carbonaceous materials used in the composite of Li2S and conductive material. The metal nitride can be defined as the above-mentioned metal nitride used in the composite of Li2S and metal nitride.

[0133] In one or more embodiments, the Li2S-containing composite can include, for example, Li2S and a lithium salt (Li a X1 b, wherein X1 can be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2, and / or their (e.g., any suitable) combination, 1 ≤ a ≤ 5, and 1 ≤ b ≤ 5), complex of Li2S, lithium salt (Li a X1 b ), and complex of conductive material (C), complex of Li2S and metal halide (M c X2 d , wherein M can be at least one metal selected from Group II to Group XV of the periodic table, X2 can be I, Br, Cl, F, and / or their (e.g., any suitable) combination, 1 ≤ c ≤ 5, and 1 ≤ d ≤ 5), complex of Li2S, metal halide (M c X2 d ), and complex of conductive material (C), complex of Li2S, lithium salt (Li a X1 b ), and metal halide (M c X2 d ), complex of Li2S, lithium salt (Li a X1 b ), metal halide (M c X2 d ), and conductive material (C), and / or their (e.g., any suitable) combination. The complex containing Li2S can be different from the simple mixture of Li2S, lithium salt, metal halide, and conductive material. The simple mixture of Li2S, metal halide, lithium salt, and conductive material may provide a high interfacial resistance because it may not be able to maintain a dense interface between Li2S and these other components, and thus may deteriorate the life characteristics of the all-solid-state secondary battery.

[0134] The complex of Li2S and lithium salt (Li a X1 b ) can be represented, for example, by Li2S-Li a X1 b , wherein 1 ≤ a ≤ 5, 1 ≤ b ≤ 5, and X1 can be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2, or their (e.g., any suitable) combination.

[0135] The complex of Li2S, lithium salt (Lia X1 b The composite of (), and conductive material (C) can be represented by, for example, Li2S-Li a X1 b -C, where 1 ≤ a ≤ 5, 1 ≤ b ≤ 5, and X1 can be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2, and / or their (e.g., any suitable) combination. The conductive material can be, for example, a carbonaceous material.

[0136] The composite of Li2S and metal halide (M c X2 d ), can be represented by, for example, Li2S-M c X2 d where 1 ≤ c ≤ 5, 1 ≤ d ≤ 5, M can be at least one metal selected from Groups II to XV of the periodic table. And X2 can be I, Br, Cl, F, or their (e.g., any suitable) combination. The conductive material can be, for example, a carbonaceous material.

[0137] The composite of Li2S, metal halide (M c X2 d ), and conductive material (C) can be represented by, for example, Li2S-M c X2 d -C, where 1 ≤ c ≤ 5, 1 ≤ d ≤ 5, M can be at least one metal selected from Groups II to XV of the periodic table. And X2 can be I, Br, Cl, F, or their (e.g., any suitable) combination. The conductive material can be, for example, a carbonaceous material.

[0138] The composite of Li2S, lithium salt (Li a X1 b ), and metal halide (M c X2 d ), can be represented by Li2S-Li a X1 b -M c X2 dIt is represented that, where 1 ≤ a ≤ 5, 1 ≤ b ≤ 5, 1 ≤ c ≤ 5, 1 ≤ d ≤ 5, X1 can be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2 or their (e.g., any suitable) combination, M can be at least one metal selected from Group II to Group XV of the periodic table, and X2 can be I, Br, Cl, F or their (e.g., any suitable) combination. The conductive material can be, for example, a carbon-based material.

[0139] Li2S, a lithium salt (Li a X1 b ), a metal halide (M c X2 d ) and a conductive material (C) complex can be represented by Li2S-Li a X1 b -M c X2 d -C, where 1 ≤ a ≤ 5, 1 ≤ b ≤ 5, 1 ≤ c ≤ 5, 1 ≤ d ≤ 5, X1 can be I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2 or their (e.g., any suitable) combination, M can be at least one metal selected from Group II to Group XV of the periodic table, and X2 can be I, Br, Cl, F or their (e.g., any suitable) combination. The conductive material can be, for example, a carbon-based material.

[0140] In the aforementioned Li2S-containing complex, for example, 1 ≤ a ≤ 4, 1 ≤ b ≤ 4, 1 ≤ c ≤ 4, 1 ≤ d ≤ 4, 1 ≤ a ≤ 3, 1 ≤ b ≤ 3, 1 ≤ c ≤ 3, 1 ≤ d ≤ 3, 1 ≤ a ≤ 2, 1 ≤ b ≤ 2, 1 ≤ c ≤ 2, or 1 ≤ d ≤ 2.

[0141] In one or more embodiments, the Li2S-containing complex can include a metal halide, and the metal halide can include at least one metal selected from Al, Mg, Ti, Sn, As, Sb, Nb, Sc, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn and Se. The metal halide can include such a metal so as to further improve the cycle characteristics of the all-solid-state secondary battery including the Li2S-containing complex.

[0142] In one or more embodiments, the Li2S-containing composite may include a metal halide, and for example, the metal halide may include AlF3, AlCl3, AlBr3, AlI3, MgF2, MgCl2, MgBr2, MgI2, TiF4, TiCl4, TiBr4, TiI4, SnF4, SnCl4, SnBr4, SnI4, AsF4, AsCl4, AsBr4, AsI4, SbF4, SbCl4, SbBr4, SbI4, and / or combinations thereof (e.g., any suitable combination). The Li2S-containing composite may include such a metal halide so as to further improve the cycle characteristics of the all-solid-state secondary battery including the Li2S-containing composite.

[0143] In one or more embodiments, the Li2S-containing composite may include, for example, a solid solution of Li2S and a lithium salt, a solid solution of Li2S and a metal halide, a solid solution of Li2S, a lithium salt, and a metal halide, and / or combinations thereof (e.g., any suitable combination). For example, the composite of Li2S and a lithium salt (Li a X1 b ), and / or the composite of Li2S, a lithium salt (Li a X1 b ), and a conductive material (C) may include a solid solution of Li2S and a lithium salt. For example, the composite of Li2S and a metal halide (M c X2 d ), and / or the composite of Li2S, a metal halide (M c X2 d ), and a conductive material (C) may include a solid solution of Li2S and a metal halide. For example, the composite of Li2S, a lithium salt (Li a X1 b ), and a metal halide (M c X2 d ), and / or the composite of Li2S, a lithium salt (Li a X1 b ), a metal halide (M c X2 d ), and a conductive material (C) may contain a solid solution of Li2S, a lithium salt, and a metal halide.

[0144] In one or more embodiments, the Li2S-containing composite may include a solid solution of Li2S and a lithium salt, a solid solution of Li2S and a metal halide, a solid solution of Li2S, a lithium salt, and a metal halide, or a combination thereof (e.g., any suitable combination), so that the ionic conductivity of the Li2S-containing composite can be increased. For example, a solid solution of Li2S and a lithium salt, a solid solution of Li2S and a metal halide, a solid solution of Li2S, a lithium salt, and a metal halide, or a combination thereof may include lithium ions, metal ions, and / or halogen ions disposed inside the Li2S microcrystals. Thus, compared with the ionic conductivity of Li2S, the ionic conductivity of the solid solution of Li2S, a lithium salt, and a metal halide can be improved. As a result, the ionic conductivity of the Li2S-containing composite can be improved, and the internal resistance of the Li2S-containing composite can be reduced. The lithium sulfide-based positive electrode active material may include such a Li2S-containing composite, thereby further improving the cycle characteristics of the all-solid-state secondary battery including the lithium sulfide-based positive electrode active material. For example, the high-rate characteristics of the all-solid-state secondary battery including such a lithium sulfide-based positive electrode active material can be further improved.

[0145] Composites of Li2S, a lithium salt, and a conductive material, composites of Li2S, a metal halide, and a conductive material, and composites of Li2S, a lithium salt, a metal halide, and a conductive material may include a conductive material. The conductive material may include, for example, carbon-based materials, metal-based materials, and / or a combination thereof (e.g., any suitable combination).

[0146] In one or more embodiments, the carbon-based materials may include, for example, fibrous carbon-based materials. The metal-based materials may include, for example, fibrous metal-based materials.

[0147] The composite of Li2S, a metal halide, and a conductive material may include fibrous carbon-based materials and / or fibrous metal-based materials, thereby further improving the electronic conductivity of the composite of Li2S, a metal halide, and a conductive material. The composite of Li2S, a metal halide, and a conductive material may include fibrous carbon-based materials and / or fibrous metal-based materials, so that electron conduction can be more easily carried out from the surface to the inside of the composite of Li2S, a metal halide, and a conductive material. The internal resistance of the positive electrode active material layer including the composite of Li2S, a metal halide, and a conductive material can be reduced, and the cycle characteristics of the all-solid-state secondary battery including the positive electrode active material layer can be further improved.

[0148] The aspect ratio of the fibrous carbonaceous material and / or the fibrous metallic material can be, for example, 2 or greater, 3 or greater, 4 or greater, 5 or greater, 10 or greater, 20 or greater, or 30 or greater. In one or more embodiments, the aspect ratio of the fibrous carbonaceous material and / or the fibrous metallic material can be, for example, in the range of about 2 to about 30, about 3 to about 30, about 4 to about 30, about 5 to about 30, about 10 to about 30, or about 20 to about 30. In one or more embodiments, the aspect ratio of the fibrous carbonaceous material and / or the fibrous metallic material can be in the range of, for example, about 2 to about 30, about 2 to about 20, about 2 to about 10, about 2 to about 8, about 2 to about 5, or about 2 to about 4. The fibrous carbonaceous material and / or the fibrous metallic material can have an aspect ratio within such a range so that the overall electronic conductivity of the composite of Li2S, the lithium salt, and the conductive material can be improved, and the imbalance in the local electronic conductivity in the composite of Li2S, the lithium salt, and the conductive material can be further alleviated.

[0149] The fibrous carbonaceous material can include, for example, carbon nanostructures. The carbon nanostructures can include, for example, CNF, CNT, carbon nanobelts, carbon nanorods, and / or their (e.g., any suitable) combination. The fibrous metallic material can include, for example, metal nanostructures. The metal nanostructures can include, for example, metal nanofibers (MNF), metal nanotubes (MNT), metal nanobelts, metal nanorods, and / or their (e.g., any suitable) combination.

[0150] The carbon nanostructures can include, for example, primary carbon nanostructures including single carbon nanostructures (e.g., consisting of a single carbon nanostructure), secondary carbon nanostructures in which multiple carbon nanostructures aggregate, and / or their (e.g., any suitable) combination.

[0151] The diameter of the primary carbon nanostructures can be, for example, in the range of about 1 nm to about 200 nm, about 1 nm to about 150 nm, about 1 nm to about 100 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 20 nm. The length of the primary carbon nanostructures can be, for example, in the range of 10 nm to about 2 μm, about 10 nm to about 1.5 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 400 nm, about 10 nm to about 300 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. The diameter and length of the primary carbon nanostructures can be measured from SEM images or TEM images. In one or more embodiments, the diameter and / or length of the primary carbon nanostructures can be measured by laser diffraction.

[0152] The secondary carbon nanostructure can be a structure formed, for example, by completely or partially clustering primary carbon nanostructures to form a nanostructure of a bundle type (or similar) or a rope type (or similar). The secondary carbon nanostructure can include, for example, a bundle type (or similar) carbon nanostructure, a rope type (or similar) carbon nanostructure, and / or a combination thereof (for example, any suitable combination). The diameter of the secondary carbon nanostructure can be, for example, in the range of about 2 nm to about 200 nm, about 3 nm to about 150 nm, about 5 nm to about 100 nm, about 5 nm to about 50 nm, about 5 nm to about 30 nm, or about 5 nm to about 20 nm. The length of the secondary carbon nanotube structure can be, for example, in the range of about 20 nm to about 2 μm, about 30 nm to about 1.5 μm, about 50 nm to about 1 μm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm to about 200 nm, or about 50 nm to 100 nm. The diameter and length of the secondary carbon nanostructure can be measured from SEM images or by optical microscopy. In one or more embodiments, the diameter and / or length of the secondary carbon nanostructure can be measured by laser diffraction. The secondary carbon nanostructure can be dispersed in, for example, a solvent or the like to be converted into a primary carbon nanostructure, which can then be used to prepare a composite of Li2S, metal halide, and a conductive material.

[0153] According to one or more embodiments, the particle size of the sulfide-based positive electrode active material (e.g., the particle size of the Li2S-containing composite) can be, for example, 10 μm or less, 8 μm or less, 5 μm or less, 4 μm or less, 2 μm or less, 1.5 μm or less, or 1 μm or less. In one or more embodiments, the particle size of the Li2S-containing composite can be, for example, in the range of about 1 μm to about 10 μm, about 2 μm to about 10 μm, about 2 μm to about 8 μm, or about 3 μm to about 8 μm. In one or more embodiments, the particle size of the Li2S-containing composite can be, for example, in the range of about 0.1 μm to about 10 μm, about 0.1 μm to about 8 μm, about 0.1 μm to about 5 μm, about 0.1 μm to about 4 μm, about 0.1 μm to about 2 μm, about 0.1 μm to about 1.5 μm, or about 0.1 μm to about 1 μm. The particles of the Li2S-containing composite can have a size within such a range, which can suppress or reduce the volume change of the sulfide-based positive electrode active material during charging or discharging, and can more effectively suppress or reduce the deterioration of the sulfide-based positive electrode active material during charging or discharging. When (e.g., when) the particle size of the Li2S-containing composite excessively (or significantly) increases (e.g., the size exceeds the above range), the volume change of the Li2S-containing composite during charging or discharging may increase, which may accelerate the deterioration of the sulfide-based positive electrode active material. As a result, the cycle characteristics of the all-solid-state secondary battery including such a sulfide-based positive electrode active material may deteriorate. The particle diameter of the Li2S-containing composite can be measured by using, for example, laser diffraction, scanning electron microscopy, etc. The size of the Li2S-containing composite can be, for example, the arithmetic average of the particle diameters of a plurality of particles measured from an SEM image by using software.

[0154] According to one or more embodiments, the size of the Li2S particles included in the Li2S-containing composite can be, for example, 2 μm or less, 1.5 μm or less, or 1 μm or less. In one or more embodiments, the size of the Li2S particles can be, for example, in the range of about 0.1 μm to about 2 μm, about 0.1 μm to about 1.5 μm, or about 0.1 μm to about 1 μm. The Li2S particles can have a size within such a range, so that the volume change of the Li2S-containing composite during charging or discharging can be suppressed or reduced, thereby suppressing or reducing the deterioration of the sulfide-based positive electrode active material including the Li2S-containing composite during charging or discharging. When (e.g., when) the size of the Li2S particles excessively (or significantly) increases (e.g., the size exceeds the above range), the volume change of the Li2S-containing composite during charging or discharging may increase, which may accelerate the deterioration of the sulfide-based positive electrode active material including the Li2S-containing composite. As a result, the cycle characteristics of the secondary battery including such a sulfide-based positive electrode active material may deteriorate.

[0155] In one or more embodiments, the ionic conductivity of the Li2S-containing composite at a temperature of about 25 °C and a pressure of about 1 atm can be, for example, 1×10 -5 S / cm or greater, 2×10 -5 S / cm or greater, 4×10 -5 S / cm or greater, 6×10 -5 S / cm or greater, 8×10 -5 S / cm or greater, or 1×10 -4 S / cm or greater. The ionic conductivity can be measured by using, for example, electrochemical impedance spectroscopy, direct current (DC) polarization methods, etc. The Li2S-containing composite can have an ionic conductivity within such a range, and thus the internal resistance of the positive electrode active material layer including the Li2S-containing composite can be further reduced. The cycle characteristics of the all-solid-state secondary battery including the positive electrode active material layer can be improved.

[0156] In one or more embodiments, the Li2S-containing composite can have, for example, 1×10 -5 S / cm or greater, 2×10 -5 S / cm or greater, 4×10 -5 S / cm or greater, 6×10 -5 S / cm or greater, 8×10 -5 S / cm or greater, or 1×10 -4 S / cm or greater of electronic conductivity at a temperature of about 25 °C and a pressure of about 1 atm. The electronic conductivity can be measured by using, for example, electrochemical impedance spectroscopy, DC polarization methods, etc. The Li2S-containing composite can have an electronic conductivity within such a range, and thus the internal resistance of the positive electrode active material layer including the Li2S-containing composite can be further reduced. The cycle characteristics of the all-solid-state secondary battery including the positive electrode active material layer can be improved. For example, relative to 100 parts by weight of the composite of Li2S, lithium salt, metal halide, and conductive material, the content (or amount) of Li2S can be about 40 parts by weight to about 80 parts by weight, the content (or amount) of the combination of lithium salt and metal halide can be about 1 part by weight to about 40 parts by weight, and the content (or amount) of the conductive material can be about 1 part by weight to about 20 parts by weight. The conductive material can be, for example, a carbon-based material. In the combination of lithium salt and metal halide, the molar ratio of lithium salt to metal halide can be, for example, in the range of about 3:1 to about 1:3, about 2:1 to about 1:2, or about 1.5:1 to about 1:1.5.

[0157] Relative to 100 parts by weight of the composite of Li2S, lithium salt, metal halide, and conductive material, the content (e.g., amount) of Li2S included in the composite of Li2S, lithium salt, metal halide, and conductive material can be in the range of, for example, about 10 parts by weight to about 80 parts by weight, about 20 parts by weight to about 70 parts by weight, about 30 parts by weight to about 60 parts by weight, or about 40 parts by weight to about 60 parts by weight. The conductive material can be, for example, a carbonaceous material.

[0158] The content (e.g., amount) of the lithium salt and metal halide included in the composite of Li2S, lithium salt, metal halide, and conductive material (e.g., the content (e.g., amount) of the combination of the lithium salt and metal halide) can be in the range of about 10 parts by weight to about 40 parts by weight, about 15 parts by weight to about 40 parts by weight, about 20 parts by weight to about 40 parts by weight, or about 25 parts by weight to about 35 parts by weight. The conductive material can be, for example, a carbonaceous material. The molar ratio of the lithium salt to the metal halide can be in the range of about 3:1 to about 1:3.

[0159] Relative to 100 parts by weight of the composite of Li2S, lithium salt, metal halide, and conductive material, the content (e.g., amount) of the conductive material included in the composite of Li2S, lithium salt, metal halide, and conductive material can be in the range of, for example, about 1 part by weight to about 20 parts by weight, about 5 parts by weight to about 20 parts by weight, or about 5 parts by weight to about 15 parts by weight. The conductive material can be, for example, a carbonaceous material.

[0160] The composite of Li2S, lithium salt, metal halide, and conductive material can have a composition of Li2S, lithium salt, metal halide, and conductive material within such a range, so that the sulfide-based cathode active material including the composite of Li2S, lithium salt, metal halide, and conductive material can provide better and suitable ionic conductivity and / or electronic conductivity.

[0161] In one or more embodiments, relative to the total weight of 100 wt% of the cathode active material layer 12, the content (e.g., amount) of Li2S included in the cathode active material layer 12 can be, for example, in the range of about 30 wt% to about 90 wt%, about 35 wt% to about 90 wt%, about 40 wt% to about 90 wt%, about 45 wt% to about 80 wt%, or about 50 wt% to about 70 wt%.

[0162] In one or more embodiments, the cathode active material layer 12 can further include, for example, a fibrous sulfide-based solid electrolyte.

[0163] In one or more embodiments, the Li2S-containing composite may further include, for example, fibrous sulfide-based solid electrolytes. The Li2S-containing composite may be a composite of Li2S and fibrous sulfide-based solid electrolytes, or a composite of Li2S, fibrous sulfide-based solid electrolytes, and the above carbon, solid electrolytes, lithium salts, metal carbides, and / or metal nitrides.

[0164] The Li2S-containing composite may include fibrous sulfide-based solid electrolytes, such that deterioration of the lithium battery can be further suppressed or reduced, and the cycle characteristics of the all-solid-state lithium battery can be further improved.

[0165] In one or more embodiments, the size of the sulfide-based positive electrode active material may be, for example, in the range of about 0.1 μm to about 50 μm, about 0.5 μm to about 30 μm, about 0.5 μm to about 20 μm, or about 1 μm to about 10 μm. The size of Li2S may be, for example, in the range of about 1 nm to about 10 μm, about 10 nm to about 5 μm, about 10 nm to about 3 μm, or about 10 nm to about 1 μm. The size of the Li2S-containing composite may be, for example, in the range of about 0.1 μm to about 50 μm, about 0.5 μm to about 30 μm, about 0.5 μm to about 20 μm, or about 1 μm to about 10 μm.

[0166] The positive electrode active material may have, for example, a particulate shape (e.g., in a particulate shape), such as a spherical shape or an oval shape. The particle size of the positive electrode active material is not limited and may be within the range applicable to positive electrode active materials for all-solid-state secondary batteries according to related art. The content (e.g., amount) of the positive electrode active material in the positive electrode layer 10 is also not limited and may be within the range applicable to positive electrode layers for all-solid-state secondary batteries according to related art. In one or more embodiments, the content (e.g., amount) of the positive electrode active material included in the positive electrode active material layer 12 may be, for example, in the range of about 10 wt% to about 99 wt%, about 10 wt% to about 90 wt%, about 10 wt% to about 80 wt%, about 10 wt% to about 70 wt%, or about 10 wt% to about 50 wt% with respect to the total weight of 100 wt% of the positive electrode active material layer 12. In one or more embodiments, the content (e.g., amount) of the positive electrode active material included in the positive electrode active material layer 12 may be, for example, in the range of about 10 wt% to about 99 wt%, about 10 wt% to about 95 wt%, about 10 wt% to about 90 wt%, about 20 wt% to about 90 wt%, about 30 wt% to about 90 wt%, about 40 wt% to about 90 wt%, or about 50 wt% to about 90 wt% with respect to the total weight of 100 wt% of the positive electrode active material layer 12.

[0167] Positive electrode layer: Solid electrolyte In one or more embodiments, 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 layer 10 may be the same as or different from the solid electrolyte included in the solid electrolyte layer 30. The solid electrolyte may be defined as in the portion of the solid electrolyte layer 30.

[0168] The D50 (average particle size) of the solid electrolyte included in the positive electrode active material layer 12 may be smaller than the D50 (average particle size) of 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) may be, for example, the median particle size (D50). When the particle size distribution measured by the laser diffraction method is calculated from particles with smaller particle sizes to particles with larger particle sizes, the median particle size (D50) may be the particle size corresponding to 50% cumulative volume.

[0169] The content (e.g., amount) of the solid electrolyte included in the positive electrode active material layer 12 may be, for example, in the range of about 1 wt% to about 40 wt%, about 1 wt% to about 30 wt%, about 1 wt% to about 20 wt%, or about 1 wt% to about 10 wt% of the total weight of 100 wt% of the positive electrode active material layer 12.

[0170] Positive electrode layer: Conductive material In one or more embodiments, the positive electrode active material layer 12 may further include a conductive material (e.g., an electronic conductor). The conductive material may be, for example, a carbon-based conductive material, a metal-based conductive material, and / or any suitable combination thereof. The carbon-based conductive material may be, for example, graphite, CB, AB, KB, carbon fiber, and / or any suitable combination thereof, but the embodiments of the present disclosure are not limited thereto. Any material may be used as long as the material can be used as a carbon-based conductive material in the art. The metal-based conductive material may be metal powder, metal fiber, and / or any suitable combination thereof, but the embodiments of the present disclosure are not limited thereto. Any material may be used as long as the material can be used as a metal-based conductive material in the art. The content (e.g., amount) of the conductive material included in the positive electrode active material layer 12 may be, for example, in the range of about 1 wt% to about 30 wt%, about 1 wt% to about 20 wt%, or about 1 wt% to about 10 wt% of the total weight of 100 wt% of the positive electrode active material layer 12.

[0171] Positive electrode layer: Binder In one or more embodiments, the positive electrode active material layer 12 may further include a binder. The binder may include, for example, SBR, PTFE, PVDF, PE, etc., but the embodiments of the present disclosure are not limited thereto. Any material may be used as long as it can be used as a binder in the art. The content (e.g., amount) of the binder included in the positive electrode active material layer 12 may be, for example, in the range of about 1 wt% to about 10 wt% of the total weight of 100 wt% of the positive electrode active material layer 12. In some embodiments, the binder may not be provided.

[0172] Positive electrode layer: Other additives In addition to the above positive electrode active material, solid electrolyte, binder, and conductive material, in some embodiments, the positive electrode active material layer 12 may further include, for example, one or more additives such as fillers, coating agents, dispersants, and / or ion conductive aids.

[0173] As the fillers, coating agents, dispersants, ion conductive aids, etc. that may be included in the positive electrode active material layer 12, suitable materials commonly used for electrodes of all-solid-state secondary batteries may be used.

[0174] Positive electrode layer: Positive electrode current collector The positive electrode current collector 11 may be provided as a plate, foil, etc. including, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof (e.g., composed of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof). In some embodiments, the positive electrode current collector 11 may not be provided. The thickness of the positive electrode current collector 11 may be, for example, in the range of about 1 μm to about 100 μm, about 1 μm to about 50 μm, about 5 μm to about 25 μm, or about 10 μm to about 20 μm.

[0175] In one or more embodiments, the positive current collector 11 may include, for example, a base film and a metal layer disposed on one side (or one surface) of the base film (e.g., one side (or one surface) or opposite two sides (or opposite two surfaces)). The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, PET, PE, PP, PBT, PI, and / or their (e.g., any suitable) combination. The base film may be, for example, an insulator. In one or more embodiments, the base film may include an insulating thermoplastic polymer, so that, in (e.g., when) a short circuit occurs, the base film may soften or liquefy to interrupt the operation of the battery, thereby suppressing or reducing a rapid 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 may be used as an electrochemical fuse and may be cut off in (e.g., when) an overcurrent occurs, thereby performing a short-circuit prevention function. The thickness of the metal layer may be adjusted to adjust the limit current and the maximum current. The metal layer may be electroplated or deposited on the base film. When the thickness of the metal layer decreases, the limit current and / or the maximum current of the positive current collector 11 may decrease, so that the stability of the lithium battery during a short circuit may be improved. In one or more embodiments, for external connection, a lead tab may be added to the metal layer. The lead tab may be welded to the metal layer or the metal layer / base film stack by ultrasonic welding, laser welding, spot welding, etc. While the base film and / or the metal layer melts during welding, the metal layer may be electrically connected to the lead tab. To weld the metal layer and the lead tab more firmly, in some embodiments, a metal chip may be added between the metal layer and the lead tab. The metal chip may be a thin sheet including the same material as the metal of the metal layer (e.g., composed of the same material as the metal of the metal layer). The metal chip may be, for example, a metal foil or a metal mesh. The metal chip may be, for example, an aluminum foil, a copper foil, or a SUS (stainless steel) foil. The metal chip may be disposed on the metal layer and then welded to the lead tab, so that the lead tab may be welded to the metal chip / metal layer stack or the metal chip / metal layer / base film stack. During welding, when the base film, the metal layer, and / or the metal chip melts, the metal layer or the metal layer / metal chip stack may be electrically connected to the lead tab. The metal chip and / or the lead tab may be added to a part of the metal layer. In one or more embodiments, the thickness of the base film may be, for example, in the range of about 1 μm to about 50 μm, about 1.5 μm to about 50 μm, about 1.5 μm to about 40 μm, or about 1 μm to about 30 μm. The base film may have a thickness in such a range, so that the weight of the electrode assembly may be reduced more effectively.In one or more embodiments, the melting point of the substrate film can be, for example, in the range of about 100°C to about 300°C, about 100°C to about 250°C, or about 100°C to about 200°C. The substrate film can have a melting point within such a range, so that the substrate film can melt during the process of welding the lead tab and can be easily bonded to the lead tab. To improve the adhesion strength between the substrate film and the metal layer, in some embodiments, the substrate film can be subjected to a surface treatment such as corona treatment. In one or more embodiments, the thickness of the metal layer can be, for example, in the range of about 0.01 μm to about 3 μm, about 0.1 μm to about 3 μm, about 0.1 μm to about 2 μm, or about 0.1 μm to about 1 μm. The metal layer can have a thickness within such a range, so that the stability of the electrode assembly can be ensured while maintaining conductivity. In one or more embodiments, the thickness of the metal sheet can be, for example, in the range of about 2 μm to about 10 μm, about 2 μm to about 7 μm, or about 4 μm to about 6 μm. The metal sheet can have a thickness within such a range, so that the metal layer and the lead tab can be more easily connected. The positive electrode current collector 11 can have such a structure, so that the weight of the positive electrode layer 10 can be reduced, thereby improving the energy density of the positive electrode layer 10 and the all-solid-state secondary battery 1.

[0176] Positive electrode layer: First inert member Refer to Figure 4 and Figure 5 and also Figures 8 to 12 , in one or more embodiments, the all-solid-state secondary battery 1 can further include a first inert member 40 (40a and / or 40b) disposed on at least one of the other side of the negative electrode current collector 21 (e.g., the side facing away from the negative electrode active material layer 22) and the other surface of the positive electrode current collector 11 (e.g., the side facing away from the positive electrode active material layer).

[0177] The first inert member 40 (40a or 40b) can be defined as the first inert member 40 (40a or 40b) of the negative electrode layer 20 as described above.

[0178] Positive electrode layer: Second inert member Refer to Figures 6 to 12 , the positive electrode layer 10 can include a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one side (or one surface) of the positive electrode current collector 11. The second inert member 50 can be disposed on one side of the positive electrode layer 10 (e.g., disposed adjacent to one side of the positive electrode layer 10).

[0179] Refer to Figure 7 , Figure 9 and Figure 11, in one or more embodiments, the second inert member 50 may be disposed on one side of the positive electrode active material layer 12 (e.g., disposed adjacent to one side of the positive electrode active material layer 12), and may be disposed between the solid electrolyte layer 30 and the positive electrode current collector 11 opposite to the solid electrolyte layer 30. The second inert member 50 may not be disposed on one side of the positive electrode current collector 11 (e.g., may not be disposed adjacent to one side of the positive electrode current collector 11). Refer to Figure 6 , Figure 8 , Figure 10 and Figure 12 , in one or more embodiments, the second inert member 50 may be disposed on one side of each of the positive electrode active material layer 12 and the positive electrode current collector 11 (e.g., disposed adjacent to one side of each of the positive electrode active material layer 12 and the positive electrode current collector 11). The second inert member 50 may be provided to prevent or reduce cracks in the solid electrolyte layer 30 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In the all-solid-state secondary battery 1 that does not include the second inert member 50, uneven pressure may be applied to the solid electrolyte layer 30 in contact with the positive electrode layer 10 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, causing cracks in the solid electrolyte layer 30, and lithium metal may grow through the cracks, increasing the possibility of short circuit.

[0180] Refer to Figures 6 to 12 , in the all-solid-state secondary battery 1, the second inert member 50 may be, for example, thicker than the first negative electrode active material layer 22. For example, the second inert member 50 may be thicker than the solid electrolyte layer 30.

[0181] Refer to Figures 6 to 12, the second inert member 50 can be around one side (e.g., one surface) of the positive electrode layer 10 (e.g., surrounding one side (e.g., one surface) of the positive electrode layer 10), and can be in contact with the solid electrolyte layer 30. The second inert member 50 can be around one side (e.g., one surface) of the positive electrode layer 10 (e.g., surrounding one side (e.g., one surface) of the positive electrode layer 10), and can be in contact with the solid electrolyte layer 30, so as to effectively suppress or reduce the cracks of the solid electrolyte layer 30 that may be caused in the portion of the solid electrolyte layer 30 that does not contact the positive electrode layer 10 due to the pressure difference during the pressing process. The second inert member 50 can be around one side (e.g., one surface) of the positive electrode layer 10 (e.g., surrounding one side (e.g., one surface) of the positive electrode layer 10), and can be separated from the negative electrode layer 20 (e.g., the first negative electrode active material layer 22). The second inert member 50 can be around one side (e.g., one surface) of the positive electrode layer 10 (e.g., surrounding one side (e.g., one surface) of the positive electrode layer 10), can be in contact with the solid electrolyte layer 30, and can be separated from the negative electrode layer 20. In one or more embodiments, the possibility of short circuit occurring due to physical contact between the positive electrode layer 10 and the first negative electrode active material layer 22 or the possibility of short circuit occurring due to overcharging of lithium can be suppressed or reduced. In some embodiments, the second inert member 50 can be disposed (e.g., simultaneously) on both 1) one side (e.g., one surface) of the positive electrode active material layer 12 and 2) one side (e.g., one surface) of the positive electrode current collector 11, so as to more effectively suppress or reduce the possibility of short circuit caused by the contact between the positive electrode current collector 11 and the negative electrode layer 20.

[0182] Refer to Figures 6 to 12 , the second inert member 50 can extend from one side of the positive electrode layer 10 to the end of the solid electrolyte layer 30. The second inert member 50 can extend to the end of the solid electrolyte layer 30, so as to suppress or reduce the occurrence of cracks at the end of the solid electrolyte layer 30. The end of the solid electrolyte layer 30 can be the outermost portion in contact with one side (e.g., one surface) of the solid electrolyte layer 30. The second inert member 50 can extend to the outermost portion in contact with one side (e.g., one surface) of the solid electrolyte layer 30. The second inert member 50 can be separated from the negative electrode layer 20 (e.g., the first negative electrode active material layer 22). The second inert member 50 can extend to the end of the solid electrolyte layer 30, but may not be in contact with the negative electrode layer 20. For example, the second inert member 50 can fill the space extending from one side of the positive electrode layer 10 to the end of the solid electrolyte layer 30.

[0183] In one or more embodiments, the area of the positive electrode active material layer 12 or the positive electrode layer 10 (e.g., the surface area of the surface of the positive electrode active material layer 12 or the positive electrode layer 10 facing the solid electrolyte layer 30) may be smaller than the area of the first negative electrode active material layer 22 or the negative electrode layer 20 (e.g., the surface area of the surface of the first negative electrode active material layer 22 or the negative electrode layer 20 facing the solid electrolyte layer 30). The area of the positive electrode active material layer 12 or the positive electrode layer 10 may be smaller than the area of the solid electrolyte layer 30 (e.g., the surface area of the surface of the solid electrolyte layer 30 facing the positive electrode layer 10).

[0184] In one or more embodiments, the second inert member 50 may be, for example, a washer. By using a washer as the second inert member 50, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively suppressed or reduced.

[0185] In one or more embodiments, the second inert member 50 may have, for example, a single-layer structure. In one or more embodiments, the second inert member 50 may have a multi-layer structure. The multi-layer structure may have, for example, a two-layer structure, a three-layer structure, or a four-layer structure, and the second inert member 50 may have a multi-layer structure such that the physical properties of the second inert member 50 can be adjusted more precisely.

[0186] In one or more embodiments, a part or the whole of the second inert member 50 may be arranged to be spaced apart from and / or separated from (e.g., separated or detached) one side (e.g., one side surface) of the positive electrode active material layer 12. A part or the whole of the second inert member 50 may be arranged to be spaced apart from and / or separated from (e.g., separated or detached) one side (e.g., one side surface) of the positive electrode active material layer 12 such that the manufacturing process of the all-solid-state secondary battery 1 can become easier and the manufacturing speed of the all-solid-state secondary battery 1 can be increased. A part or the whole of the second inert member 50 may be arranged to be spaced apart from and / or separated from (e.g., separated or detached) one side (e.g., one side surface) of the positive electrode active material layer 12, and thus the volume change of the positive electrode active material layer 12 in the lateral direction during charging or discharging can be more effectively accommodated, thereby further improving the life characteristics of the all-solid-state secondary battery 1. The distance between the second inert member 50 and one side (e.g., one side surface) of the positive electrode active material layer 12 may independently be in the range of, for example, about 0.1 μm to about 10 mm, about 1 μm to about 1 mm, about 1 μm to about 500 μm, about 1 μm to about 100 μm, about 1 μm to about 50 μm, or about 1 μm to about 10 μm.

[0187] Refer to Figures 1 to 12, the second inert member 50 can be selected from, for example, the materials used in the above-mentioned first inert member 40 (40a and / or 40b). The second inert member 50 may not include (for example, may exclude) electrode active materials. In one or more embodiments, the second inert member 50 can be, for example, a flame-retardant inert member, an electronically insulating inert member, an ionically insulating inert member, or an elastic inert member.

[0188] Solid electrolyte layer Solid electrolyte layer: Solid electrolyte Refer to Figures 1 to 12 , the all-solid-state secondary battery 1 can include a solid electrolyte layer 30 between the positive electrode layer 10 and the negative electrode layer 20. The solid electrolyte layer 30 can include, for example, a solid electrolyte and / or a (for example, any suitable) combination of a solid electrolyte and a gel electrolyte.

[0189] The solid electrolyte can include, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, polymer solid electrolytes, and / or their (for example, any suitable) combination.

[0190] In one or more embodiments, the solid electrolyte can be, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte can include, for example, those selected from 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 (where m and n are both positive numbers, and Z can be one selected from Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are both positive numbers, and M can be one selected from P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 x 2), Li 7-x PS 6-x Br x (where 0 x 2) and Li 7-x PS6-x I x (wherein at least one of 0 x 2). For example, a sulfide-based solid electrolyte can be prepared by melt quenching or mechanical milling of raw materials such as Li2S or P2S5. For example, after such treatment, heat treatment can be carried out. The solid electrolyte can be in an amorphous state, a crystalline state, or a mixture thereof. In one or more embodiments, the solid electrolyte can be a material that includes at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above materials such as sulfide-based solid electrolytes. For example, in some embodiments, the solid electrolyte can be a material that includes Li2S-P2S5. When a material that includes Li2S-P2S5 (e.g., when) is used as a sulfide-based solid electrolyte material for forming a solid electrolyte, the mixing molar ratio of Li2S to P2S5 (e.g., Li2S:P2S5) can be in the range of about 20:80 to about 90:10, about 25:75 to about 90:10, about 30:70 to about 70:30, or about 40:60 to about 60:40. In one or more embodiments, the sulfide-based solid electrolyte can include, for example, a thiargite-type or (quasi) solid electrolyte represented by the formula SE: Formula SE Li + 12-n-x A n+ X 2- 6-x Y - x .

[0191] In formula SE, A can be P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta, X can be S, Se, or Te, Y can be Cl, Br, I, F, CN, OCN, SCN, or N3, 1 ≤ n ≤ 5, and 0 ≤ x ≤ 2. In one or more embodiments, the sulfide-based solid electrolyte can be, for example, a thiargite-type or (quasi) compound that includes at least one selected from Li 7-x PS 6-x Cl x (wherein 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (wherein 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (wherein 0 ≤ x ≤ 2). In some embodiments, the sulfide-based solid electrolyte can be, for example, a thiargite-type or (quasi) compound that includes at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0192] The argyrodite-type or (quasi-)solid-state electrolyte may have a density of about 1.5 g / cc to about 2.0 g / cc. The argyrodite-type or (quasi-)solid-state electrolyte may have a density of 1.5 g / cc or greater, such that the internal resistance of the all-solid-state secondary battery 1 can be reduced, and Li penetration through the solid electrolyte layer 30 can be effectively suppressed or reduced.

[0193] Oxide-based solid-state electrolytes may include, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (where 0 ≤ x < 1 and 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 (where 0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (where 0 < x < 2, 0 < y < 1, and 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (where M = Te, Nb or Zr and 0 ≤ x ≤ 10) and / or their (e.g., any suitable) combinations. Oxide-based solid-state electrolytes can be prepared, for example, by sintering or the like.

[0194] In one or more embodiments, the oxide-based solid electrolyte can be, for example, selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (LLZO doped with M) (where M = Ga, W, Nb, Ta or Al, 0 < a < 2, and 0 ≤ x ≤ 10), among garnet-type (or like) solid electrolytes.

[0195] For example, the polymer solid electrolyte can include a mixture of a lithium salt and a polymer, or can include a polymer having ion-conductive functional groups. The polymer solid electrolyte can be, for example, a polymer electrolyte that is in a solid state at a temperature of about 25 °C and a pressure of about 1 atm. The polymer solid electrolyte may not include (e.g., may exclude) a liquid, for example. In one or more embodiments, the polymer solid electrolyte can include a polymer, and the polymer can include, for example, polyethylene oxide (PEO), PVDF, poly(vinylidene fluoride - hexafluoropropylene) (PVDF - HFP), poly(styrene - b - ethylene oxide) (PS - PEO) block copolymer, 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(methyl methacrylate) (PMMA), polyethylene glycol (PEG), PAN, polytetrafluoroethylene (PTFE), poly(ethylenedioxythiophene) (PEDOT), polypyrrole (PPY), polyaniline, polyacetylene, NAFION™, AQUIVION ® , FLEMION ® , GORE™, ACIPLEX™, MORGANE ® - ADP, sulfonated poly(ether ketone) (SPEEK), sulfonated poly(arylene ether ketone sulfone) (SPAEKKS), sulfonated poly(arylene ether ketone) (SPAEK), poly[bis(benzimidazole benzophenanthroline)] (SPBIBI), lithium 9,10 - diphenylanthracene - 2 - sulfonate (DPASLi + ) and / or their (e.g., any suitable) combination, but the embodiments of the present disclosure are not limited thereto. Any material can be used as long as the material can be used for polymer electrolytes in the art. As the lithium salt, any material can be used as long as the material can be used as a lithium salt in the art. The lithium salt can include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C xF 2x+1 SO2)(C y F 2y+ 1SO2), where x and y are each natural numbers from 1 to 20, LiCl, LiI, and / or their (e.g., any suitable) mixture. The polymer included in the polymer solid electrolyte can be, for example, a compound including 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 can be, for example, 1,000 daltons or greater, 10,000 daltons or greater, 100,000 daltons or greater, or 1,000,000 daltons or greater.

[0196] In one or more embodiments, the gel electrolyte can be, for example, a polymer gel electrolyte. In one or more embodiments, the gel electrolyte can have a gel state without including, for example, a polymer.

[0197] Polymer gel electrolytes can include, for example, a liquid electrolyte and a polymer, or can include an organic solvent and a polymer having an ion-conductive functional group. A polymer gel electrolyte can be, for example, a polymer electrolyte in a gel state at a temperature of about 25 °C and a pressure of about 1 atm. In some embodiments, a polymer gel electrolyte can have, for example, a gel state without including a liquid. The liquid electrolyte used in the polymer gel electrolyte can include, for example, a mixture of an ionic liquid, 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, and / or a (for example, any suitable) mixture of a lithium salt and an ionic liquid. The polymer used in the polymer gel electrolyte can be selected from the polymers used in solid polymer electrolytes. The organic solvent can be selected from the organic solvents used in liquid electrolytes. Non-limiting examples of the organic solvent can include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyl dioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, and / or a (for example, any suitable) mixture thereof. The lithium salt can be selected from the lithium salts used in polymer solid electrolytes. An ionic liquid can refer to a salt that is liquid at room temperature or a room-temperature molten salt having a melting point at room temperature or lower and consisting only of ions (for example, composed of ions). The ionic liquid can include, for example, at least one selected from among compounds including: a) one or more cations selected from the group consisting of ammonium cations, pyrrolidinium cations, pyridinium cations, pyrimidinium cations, imidazolium cations, piperidinium cations, pyrazolium cations, oxazolium cations, pyridazinium cations, phosphonium cations, sulfonium cations, triazolium cations, and / or a (for example, any suitable) mixture thereof; and b) selected from BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 2- , CF3SO3 - , (FSO2)2N- , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - At least one anion among them. In some embodiments, the polymer solid electrolyte can be impregnated in, for example, a liquid electrolyte in a secondary battery to form a polymer gel electrolyte. In some embodiments, the polymer gel electrolyte can further include inorganic particles. In one or more embodiments, the polymer included in the polymer gel electrolyte can be, for example, a compound including 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 can be, for example, 500 daltons or greater, 1,000 daltons or greater, 10,000 daltons or greater, 100,000 daltons or greater, or 1,000,000 daltons or greater.

[0198] Solid electrolyte layer: Binder In one or more embodiments, the solid electrolyte layer 30 can include, for example, a binder. The binder included in the solid electrolyte layer 30 can include, for example, SBR, PTFE, PVDF, PE, etc., but the embodiments of the present disclosure are not limited thereto. Any material can be used as long as the material can be used as a binder in the art. The binder of the solid electrolyte layer 30 can be the same as or different from the binders included in the positive electrode active material layer 12 and the first negative electrode active material layer 22. In some embodiments, the binder can be not provided.

[0199] With respect to the total weight of 100 wt% of the solid electrolyte layer 30, the content (e.g., amount) of the binder included in the solid electrolyte layer 30 can be in the range of about 0.1 wt% to about 10 wt%, about 0.1 wt% to about 5 wt%, about 0.1 wt% to about 3 wt%, about 0.1 wt% to about 1 wt%, about 0 wt% to about 0.5 wt%, or about 0 wt% to about 0.1 wt%.

[0200] The present disclosure will be described in more detail by the following examples and comparative examples. However, the examples are for illustrative purposes only, and the scope of the present disclosure is not limited by the examples.

[0201] Preparation of the positive electrode active material of the sulfide-based composite Preparation Example 1: Positive electrode active material of Li2S-LiI-CNF composite Mix Li2S and LiI in a weight ratio of 30:20. Mechanically grind the obtained mixture using a ball mill to prepare a Li2S-LiI composite. The grinding conditions include a temperature of 25 °C, a speed of 510 rpm, and 10 hours.

[0202] Mix the Li2S-LiI composite and carbon nanofibers (CNF) in a weight ratio of 50:10. Mechanically grind the obtained mixture using a ball mill to prepare a Li2S-LiI-CNF composite. The grinding conditions include a temperature of 25 °C, a speed of 510 rpm, and 10 hours. The Li2S-CNF-LiI composite is used as a sulfide-based positive electrode active material.

[0203] Preparation Example 2: Li2S-LiI-AlI3-CNF composite First stage Mix LiI and AlI3 in a molar ratio of 1:1 to prepare a first mixture.

[0204] Mix Li2S and the first mixture in a weight ratio of 40:20 to prepare a second mixture. Mechanically grind the second mixture using a ball mill to prepare a Li2S-LiI-AlI3 composite. The grinding conditions include a temperature of 25 °C, a speed of 600 rpm, and 10 hours. The grinding energy applied to the sample during grinding is 28 G.

[0205] Second stage Mix the Li2S-LiI-AlI3 composite and CNF in a weight ratio of 60:10 to prepare a third mixture. Mechanically grind the third mixture using a ball mill to prepare a Li2S-LiI-AlI3-CNF composite. The grinding conditions include a temperature of 25 °C, a speed of 600 rpm, and 10 hours. The grinding energy applied to the sample during grinding is 28 G. The Li2S-LiI-AlI3-CNF composite is used as a sulfide-based positive electrode active material.

[0206] The weight ratio of each component of the Li2S-LiI-AlI3-CNF composite is 40:15:5:10.

[0207] Reference Preparation Example 1: Mixture of Li2S, LiI, AlI3, and CNF Mix LiI and AlI3 in a molar ratio of 1:1 to prepare a first mixture.

[0208] Mix Li2S and the first mixture in a weight ratio of 40:20, and further mix the mixture of Li2S, LiI, and AlI3 with CNF in a weight ratio of 60:10 to be used as a sulfide-based positive electrode active material.

[0209] Manufacture of All-Solid-State Secondary Battery Example 1: Elastic Sheet (50 μm) / Positive Electrode Layer (112 μm, NCA) / Solid-State Electrolyte Layer (30 μm) / Negative Electrode Layer (37 μm, Si Particles:CNT:Binder = 3:1:0.28 by Weight): (Si-CNT:Ag-C = 3:1 by Weight) Preparation of Positive Electrode Layer Prepare LiNi coated with Li2O-ZrO2 (LZO) 0.8 Co 0.15 Al 0.05 O2 (NCA) as the positive electrode active material. Prepare the positive electrode active material coated with LZO according to the method disclosed in Korean Patent with Publication No. 10-2016-0064942. Prepare Li6PS5Cl (D50 = 0.5 μm, crystal), which is a thiogermanate (or similar) crystal, as the solid-state electrolyte. Prepare PTFE binder as the binder. Prepare CNF as the conductive agent. Mix the slurry obtained from these materials with xylene solvent so that the weight ratio of positive electrode active material:solid-state electrolyte:conductive agent:binder is 84:11:3:2. Mold the slurry into a sheet form, and then vacuum dry the sheet at a temperature of 40 °C for 8 hours to prepare the positive electrode sheet. Arrange the prepared positive electrode sheet on the carbon layer of the positive electrode current collector composed of an aluminum foil coated with a carbon layer on one side, and heat and roll press it at a temperature of 85 °C to prepare the positive electrode layer. The total thickness of the positive electrode layer is about 112 μm. The thickness of the positive electrode active material layer is about 92 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0210] Measure the initial charge capacity of the positive electrode active material layer by using the above half-cell. The initial charge capacity of the positive electrode active material layer is 25 mAh.

[0211] Preparation of Negative Electrode Layer Prepare a SUS (stainless steel) foil with a thickness of 10 μm as the negative electrode current collector. Prepare silicon (Si) particles with an average particle size of 1 μm as the first negative electrode active material. As the second negative electrode active material, prepare a mixture of CB particles with an average particle size of about 30 nm and silver (Ag) particles with an average particle size of about 60 nm at a weight ratio of 3:1. Prepare CNT as a fibrous carbon material. CNT includes a carbon nanotube primary structure and a carbon nanotube secondary structure. The carbon nanotube primary structure consists of one carbon nanotube unit. The length of the carbon nanotube unit is in the range of 200 nm to 300 nm, and the diameter of the carbon nanotube unit is in the range of about 5 nm to about 10 nm. The carbon nanotube secondary structure is formed by aggregating multiple carbon nanotube units. The length of the carbon nanotube secondary structure is about 5 μm, and the diameter of the carbon nanotube secondary structure is about 40 nm.

[0212] 3 g of a mixture of silicon (Si) particles and CNTs with a weight ratio of 3:1 and 1 g of a mixture of carbon black (CB) and silver (Ag) with a weight ratio of 3:1 were placed in a container, and 4 g of an N-methyl-2-pyrrolidone (NMP) solution containing 7 wt% of a PVDF binder (#9300 manufactured by Kureha Chemical Co., Ltd.) was added thereto to prepare a mixed solution. While adding NMP drop by drop to the prepared mixed solution, the mixed solution was stirred to prepare a slurry. The prepared slurry was applied to a SUS substrate / foil using a bar coater, dried in air at a temperature of 80 °C for 10 minutes, and then vacuum dried at a temperature of 40 °C for 10 hours to prepare a stacked body. The prepared stacked body was cold roll-pressed to flatten its surface, thereby preparing a negative electrode layer having a first negative electrode active material layer / negative electrode current collector structure. The thickness of the first negative electrode active material layer was about 27 μm.

[0213] The initial charge capacity of the first negative electrode active material layer was measured using the above half-cell. The initial charge capacity of the first negative electrode active material layer was 9.0 mAh.

[0214] The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer was 0.36. By charging from the first OCV to a voltage of 4.25 V vs. Li / Li + the initial charge capacity of the positive electrode active material layer was determined. By charging from the second OCV to a voltage of 0.01 V vs. Li / Li + the initial charge capacity of the first negative electrode active material layer was determined.

[0215] In each of Examples 2 to 5 and Comparative Example 1, the ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer measured under the same conditions as in Example 1 to the initial charge capacity (A) of the positive electrode active material layer was in the range of 0.23 to 0.44.

[0216] Preparation of Solid-State Electrolyte Layer A mixture was prepared by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of a solid-state electrolyte Li6PS5Cl (D50 = 3.0 μm, crystalline), which is a thio-LISICON-type (or like) crystal. Octyl acetate was added to the prepared mixture and stirred to prepare a slurry. Using a bar coater, the prepared slurry was applied to a nonwoven fabric placed on a PET substrate and dried in air at a temperature of 80 °C for 10 minutes to prepare a stacked body. The prepared stacked body was vacuum dried at a temperature of 80 °C for 2 hours to prepare a solid-state electrolyte layer.

[0217] Inert component: elastic sheet A porous polyurethane foam sheet with a thickness of 50 μm was prepared as the elastic sheet.

[0218] Manufacture of all-solid-state secondary battery A solid electrolyte layer was disposed on the negative electrode layer such that the first negative electrode active material layer was in contact with the solid electrolyte layer, and a positive electrode layer was disposed on the solid electrolyte layer such that the positive electrode active material layer was in contact with the solid electrolyte layer, thereby preparing a stacked body.

[0219] The prepared stacked body was hot-pressed at a temperature of 85 °C and a pressure of 500 MPa for 30 minutes. Through such pressing, the solid electrolyte layer can be sintered to improve battery characteristics. The thickness of the sintered solid electrolyte layer is about 30 μm. The density of the Li6PS5Cl solid electrolyte, which is a thio-LISICON (or type) crystal included in the sintered solid electrolyte layer, is 1.6 g / cc. The area of the solid electrolyte layer is equal to the area of the negative electrode layer. An elastic sheet was additionally disposed on the positive electrode current collector of the pressed stacked body.

[0220] The stacked body further including the elastic sheet was placed in a bag and vacuum-sealed to manufacture an all-solid-state secondary battery. Parts of the positive electrode current collector and the negative electrode current collector each extend to the outside of the sealed battery and are used as the positive electrode terminal and the negative electrode terminal, respectively.

[0221] Example 2: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3.2:0.8:0.28 weight ratio): (Si-CNT:Ag-C = 3:1 weight ratio) An all-solid-state secondary battery was manufactured in substantially the same manner as in Example 1 except that the composition ratio of the first negative electrode active material to the fibrous carbonaceous material was changed to 3.2:0.8 (4:1).

[0222] Example 3: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3.5:0.5:0.28 weight ratio): (Si-CNT:Ag-C = 3:1 weight ratio) An all-solid-state secondary battery was manufactured in substantially the same manner as in Example 1 except that the composition ratio of the first negative electrode active material to the fibrous carbonaceous material was changed to 3.5:0.5 (7:1).

[0223] Example 4: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles: CNT: Binder = 3.6:0.4:0.28 by weight): (Si-CNT:Ag-C = 3:1 by weight) A all-solid-state secondary battery is manufactured in substantially the same manner as in Example 1, except that the composition ratio of the first negative electrode active material to the fibrous carbon material is changed to 3.6:0.4 (9:1).

[0224] Example 5: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles: CNT: Binder = 2:2:0.28 by weight): (Si-CNT:Ag-C = 3:1 by weight) A all-solid-state secondary battery is manufactured in substantially the same manner as in Example 1, except that the composition ratio of the first negative electrode active material to the fibrous carbon material is changed to 2:2 (1:1).

[0225] Example 6: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles: CNT: Binder = 3:1:0.28 by weight): (Si-CNT: Carbon supporting Ag = 3:1 by weight) A all-solid-state secondary battery is manufactured in substantially the same manner as in Example 1, except that as the second negative electrode active material, 1 g of CB supporting silver particles as described is used instead of 1 g of a mixture of CB and silver particles with a weight ratio of 3:1.

[0226] Preparation of CB supporting silver particles CB is dispersed in a 1.0 M sulfuric acid solution and stirred for 2 hours, then filtered and dried to prepare acid-treated CB.

[0227] To a mixed solvent of 1500 g of distilled water, 1500 g of ethanol, and 30 g of glycerol, 10 g of acid-treated CB was added and stirred, and then 2 g of AgNO3 was added and stirred to prepare a mixed solution. The particle size of the CB was 80 nm. A reducing agent was added to the mixed solution, and silver ions were reduced and supported on the CB. The CB supporting silver-containing particles thereon was filtered, cleaned, and dried to prepare a composite negative electrode active material. As a result of scanning electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements, it was confirmed that a plurality of silver-containing particles were supported on the CB particles. The silver-containing particles include silver particles, silver oxide (AgO) particles, and composite particles of silver (Ag) and silver oxide (AgO). The content (e.g., amount) of the silver-containing particles included in the composite negative electrode active material (CB supporting silver-containing particles thereon) was 5 wt%. The average particle size of the silver particles was 10 nm.

[0228] Comparative Example 1: Elastic sheet (50 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3.6:0.4:0 weight ratio): (Si-CNT:Ag-C = 4:0 weight ratio) A all-solid-state secondary battery was manufactured in substantially the same manner as in Example 4, except that a mixture of 4 g of silicon (Si) particles and CNTs with a weight ratio of 9:1 was used, a mixture of CB and silver (Ag) with a weight ratio of 3:1 was not used, and no binder was used.

[0229] Reference Example 1: Elastic sheet (100 μm) / Positive electrode layer (112 μm, NCA) / Solid electrolyte layer (30 μm) / Negative electrode layer (17 μm, Ag-C + Binder): (Si-CNT:Ag-C = 0:4 weight ratio) A all-solid-state secondary battery was manufactured in substantially the same manner as in Example 1, except that a mixture of silicon (Si) particles and CNTs with a weight ratio of 3:1 was not used, a mixture of 4 g of CB and silver (Ag) with a weight ratio of 3:1 was used, the thickness of the negative electrode active material layer became 7 μm, and the thickness of the elastic sheet became 100 μm. The thickness of the negative electrode layer is the total thickness of the negative electrode current collector and the negative electrode active material layer.

[0230] Example 7: Positive electrode layer (113.8 μm, Li2S-LiI-CNF) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3:1:0.28 weight ratio): (Si-CNT:Ag-C = 3:1 weight ratio) A all-solid-state secondary battery was manufactured in substantially the same manner as in Example 1, except that the following positive electrode layer including a sulfide-based positive electrode active material was used and no elastic sheet was used.

[0231] Preparation of the positive electrode layer Prepare the Li2S-LiI-CNF composite prepared in Preparation Example 1 as the positive electrode active material. Prepare Li6PS5Cl (D50 = 3.0 μm, crystalline), which is a thiogermanate (or similar) crystal, as the solid electrolyte. Prepare PTFE as the binder. Mix these materials at a weight ratio of positive electrode active material:solid electrolyte:binder of 60:40:1.2 to prepare a positive electrode mixture. Obtain the positive electrode mixture by mixing using a ball mill.

[0232] Arrange the positive electrode mixture on one side of a positive electrode current collector composed of an aluminum foil coated with carbon on one surface, and press it at a pressure of 200 MPa for 10 minutes to prepare the positive electrode layer. The total thickness of the positive electrode layer is about 113.8 μm. The thickness of the positive electrode active material layer is about 93.8 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0233] In Example 7, the ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is 0.35. By charging from the first OCV to a voltage of 2.8 V vs. Li / Li + to determine the initial charge capacity of the positive electrode active material layer. By charging from the second OCV to a voltage of 0.01 V vs. Li / Li + to determine the initial charge capacity of the first negative electrode active material layer.

[0234] Comparative Example 2: Positive electrode layer (113.8 μm, Li2S-LiI-CNF) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:binder = 3.6:0.4:0 weight ratio): (Si-CNT:Ag-C = 4:0 weight ratio) Except for using the positive electrode layer of Example 7, using a 4 g mixture of silicon (Si) particles and CNTs in a weight ratio of 9:1, not using a mixture of CB and silver (Ag) in a weight ratio of 3:1, not using a binder, and not using an elastic sheet, manufacture an all-solid-state secondary battery in substantially the same manner as in Example 4.

[0235] Reference Example 2: Elastic sheet (50 μm) / Positive electrode layer (113.8 μm, Li2S-LiI-CNF) / Solid electrolyte layer (30 μm) / Negative electrode layer (17 μm, Ag-C + binder): (Si-CNT:Ag-C = 0:4 weight ratio) An all-solid-state secondary battery is manufactured in substantially the same manner as in Example 1, except that instead of using the mixture of silicon (Si) particles and CNTs with a weight ratio of 3:1 in the positive electrode layer of Example 7, a mixture of 4 g of carbon black (CB) and silver (Ag) with a weight ratio of 3:1 is used, and the thickness of the negative electrode active material layer is changed to 7 μm. The thickness of the negative electrode layer is the total thickness of the negative electrode current collector and the negative electrode active material layer.

[0236] Example 8: Positive electrode layer (113.8 μm, Li2S-LiI-AlI3-CNF composite) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3:1:0.28 weight ratio): (Si-CNT:Ag-C = 3:1 weight ratio) An all-solid-state secondary battery is manufactured in substantially the same manner as in Example 7, except that the Li2S-LiI-AlI3-CNF composite prepared in Preparation Example 2 is used instead of the Li2S-LiI-CNF composite as the positive electrode active material.

[0237] Reference Example 3: Positive electrode layer (113.8 μm, Li2S-LiI-AlI3-CNF mixture) / Solid electrolyte layer (30 μm) / Negative electrode layer (37 μm, Si particles:CNT:Binder = 3:1:0.28 weight ratio): (Si-CNT:Ag-C = 3:1 weight ratio) An all-solid-state secondary battery is manufactured in substantially the same manner as in Example 7, except that a simple mixture of Li2S, LiI, AlI3, and CNF prepared in Reference Preparation Example 1 is used instead of the Li2S-LiI-CNF composite as the positive electrode active material.

[0238] Evaluation Example 1-1: Evaluation of volume change during charging or discharging (NCA positive electrode active material) After only the first-cycle charging operation in the charge / discharge test of Evaluation Example 3 below is performed on each of the all-solid-state secondary batteries manufactured in Example 1 and Reference Example 1, SEM images of the cross-sections of each all-solid-state secondary battery are measured to observe the change in thickness.

[0239] After the first-cycle charging, a lithium metal layer is formed between the first negative electrode active material layer and the negative electrode current collector.

[0240] In the all-solid-state secondary battery of Example 1, the thickness of the lithium metal layer formed between the first negative electrode active material layer and the negative electrode current collector after the initial charging is about 8 μm, which is less than the thickness of the first negative electrode active material layer after charging (34 μm).

[0241] The thickness increase of the all-solid-state secondary battery of Example 1 after initial charging is 10% or less of the initial thickness of the all-solid-state secondary battery. Therefore, during the charging or discharging process of the all-solid-state secondary battery of Example 1, volume change is suppressed or reduced.

[0242] In the all-solid-state secondary battery of Example 1, an elastic member with a thickness of 50 μm is used to accommodate volume change during charging or discharging. In one or more embodiments, the all-solid-state secondary battery includes an elastic member with a thickness of 50 μm, such that the energy density of the all-solid-state secondary battery is partially reduced.

[0243] In the all-solid-state secondary battery of Reference Example 1, the thickness of the lithium metal layer formed between the first negative electrode active material layer and the negative electrode current collector after initial charging is about 30 μm, which is greater than the thickness (7 μm) of the first negative electrode active material layer after charging.

[0244] The thickness increase of the all-solid-state secondary battery of Reference Example 1 after initial charging is greater than 15% of the initial thickness of the all-solid-state secondary battery. Therefore, during the charging or discharging process of the all-solid-state secondary battery of Reference Example 1, volume change is significant.

[0245] In the all-solid-state secondary battery of Reference Example 1, an elastic member with a thickness of 100 μm is used to accommodate volume change during charging or discharging. In one or more comparative examples, the all-solid-state secondary battery includes an elastic member with a thickness of 100 μm, and thus the energy density of the all-solid-state secondary battery is further reduced.

[0246] Evaluation Example 1-2: Evaluation of volume change during charging or discharging (Li2S-LiI-CNF positive electrode active material) After only the first-cycle charging operation in the following charging / discharging test of Evaluation Example 3 was performed on each of the all-solid-state secondary batteries manufactured in Example 7 and Reference Example 2, SEM images of the cross-sections of each all-solid-state secondary battery were measured to observe thickness changes.

[0247] After the first-cycle charging, a lithium metal layer is formed between the first negative electrode active material layer and the negative electrode current collector.

[0248] In the all-solid-state secondary battery of Example 7, the thickness of the lithium metal layer formed between the first negative electrode active material layer and the negative electrode current collector after initial charging is about 8 μm, which is less than the thickness (34 μm) of the first negative electrode active material layer after charging.

[0249] The thickness increase of the all-solid-state secondary battery of Example 7 after initial charging is 5% or less of the initial thickness of the all-solid-state secondary battery. Therefore, during the charging or discharging process of the all-solid-state secondary battery of Example 7, volume change is not significant.

[0250] In the all-solid-state secondary battery of Example 7, an elastic member for accommodating volume changes during charging or discharging was not used. Therefore, due to the elastic member, the energy density of the all-solid-state secondary battery was not reduced.

[0251] In the all-solid-state secondary battery of Reference Example 2, the thickness of the lithium metal layer formed between the first negative electrode active material layer and the negative electrode current collector after initial charging was about 30 μm, which was greater than the thickness (7 μm) of the first negative electrode active material layer.

[0252] The increase in thickness of the all-solid-state secondary battery of Reference Example 2 after initial charging was greater than 10% of the initial thickness of the all-solid-state secondary battery. Therefore, during the charging or discharging process of the all-solid-state secondary battery of Reference Example 2, the volume change was significant.

[0253] In the all-solid-state secondary battery of Reference Example 2, an elastic member with a thickness of 50 μm was used to accommodate the increased volume change during charging or discharging. In one or more comparative examples, the all-solid-state secondary battery included an elastic member with a thickness of 50 μm, such that the energy density of the all-solid-state secondary battery was partially reduced.

[0254] Evaluation Example 2: XRD analysis and SEM analysis Using Cu Kα radiation, X-ray diffraction (XRD) spectra were measured for the bare Li2S, pulverized Li2S, and Li2S-LiI-AlI3-CNF composite prepared in Preparation Example 2. The measurement results are shown in Table 1. The Li2S microcrystal size and lattice constant were derived from the first peak of the (111) crystal plane of Li2S that appeared in the XRD spectrum.

[0255] Except for changing the mixture of Li2S and the first mixture (a mixture of LiI and AlI3 with a molar ratio of 1:1) in the first stage of Preparation Example 2 with a weight ratio of 40:20 to 50 parts by weight of Li2S, pulverized Li2S was prepared by grinding under the same conditions. The second stage was not performed.

[0256] Using a laser particle size analyzer (PSA) and SEM, the particle size of the composite (i.e., D50 particle size) and the Li2S particle size of the composite were measured for the bare Li2S, pulverized Li2S, and Li2S-LiI-AlI3-CNF composite prepared in Preparation Example 2. The measurement results are shown in Table 1.

[0257] Table 1

[0258] As shown in Table 1, compared with bare Li2S, the particle size and microcrystal size of Li2S in the Li2S-LiI-AlI3-CNF composite of Preparation Example 2 are significantly reduced.

[0259] Although not shown in Table 1, the Li2S lattice constant of the Li2S-LiI-AlI3-CNF composite of Preparation Example 2 is greater than that of bare Li2S.

[0260] It is determined that the increase in the Li2S lattice constant of the Li2S-LiI-AlI3-CNF composite compared to that of bare Li2S is due to the dissolution of LiI and / or AlI3 in the Li2S crystal. Therefore, it is confirmed that Li2S, LiI, and / or AlI3 form a solid solution in the Li2S-LiI-AlI3-CNF composite.

[0261] Although not shown in Table 1, the D50 particle size of the Li2S-LiI-AlI3-CNF composite prepared in Preparation Example 2 is 8 μm, the D10 particle size is greater than 2.0 μm, and the D90 particle size is 25 μm.

[0262] Evaluation Example 3: Charge / Discharge Test The charge / discharge characteristics of each all-solid-state secondary battery manufactured in Examples 1 to 6, Comparative Example 1, and Reference Example 1 were evaluated by the following charge / discharge test. The charge / discharge test was carried out by placing the all-solid-state secondary battery in a constant-temperature bath at a temperature of 45°C.

[0263] In the first cycle, each all-solid-state secondary battery was charged at a constant current of 0.5 mA / cm 2 for 12.5 hours until the battery voltage reached 3.9 V to 4.25 V. Subsequently, each all-solid-state secondary battery was discharged at a constant current of 0.5 mA / cm 2 for 12.5 hours until the battery voltage reached 2.5 V.

[0264] The charge / discharge characteristics of the all-solid-state secondary batteries manufactured in Examples 7, 8, Comparative Example 2, Reference Example 1, and Reference Example 2 were each evaluated by the following charge / discharge test. The charge / discharge test was carried out by placing the all-solid-state secondary battery in a constant-temperature bath at a temperature of 45°C.

[0265] In the first cycle, each all-solid-state secondary battery was charged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 2.5 V to 2.8 V. Subsequently, each all-solid-state secondary battery was discharged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 0.3 V.

[0266] The discharge capacity of the first cycle is used as the standard capacity. Starting from the second cycle, charging and discharging are performed under the same conditions as those of the first cycle until a specific cycle (for example, the 500th cycle or more). The measurement results are shown in Table 2.

[0267] The number of cycles refers to the number of cycles required for the discharge capacity to decrease to 80% of the standard capacity after the second cycle. It is considered that the life characteristics are improved as the number of cycles increases.

[0268] Table 2

[0269] As shown in Table 2, for each all-solid-state secondary battery of Examples 1 to 6, during charging or discharging, the volume change is suppressed or reduced, and the increase in internal resistance is suppressed or reduced, so that the all-solid-state secondary batteries of Examples 1 to 6 all exhibit excellent or appropriate life characteristics.

[0270] Compared with the all-solid-state secondary battery of Comparative Example 1 that does not include the second negative electrode active material and the binder, each all-solid-state secondary battery of Examples 1 to 6 has improved life characteristics.

[0271] In the all-solid-state secondary battery of Comparative Example 1, it is determined that the life characteristics of the all-solid-state secondary battery deteriorate due to the disconnection of the conduction path caused by electrode separation and / or the separation of the negative electrode active material from the fibrous carbonaceous material during the charging or discharging process.

[0272] For each all-solid-state secondary battery of Examples 7 and 8, during charging or discharging, the volume change is suppressed or reduced, and the increase in internal resistance is suppressed or reduced, so that the all-solid-state secondary batteries of Examples 7 and 8 all exhibit excellent or appropriate life characteristics.

[0273] Compared with the all-solid-state secondary battery of Comparative Example 2 that does not include the second negative electrode active material and the binder, each all-solid-state secondary battery of Examples 7 and 8 has improved life characteristics.

[0274] In the all-solid-state secondary battery of Comparative Example 2, it is determined that the life of the all-solid-state secondary battery deteriorates due to an increase in the interfacial resistance between the first negative electrode active material layer and the solid electrolyte layer or between the first negative electrode active material layer and the negative electrode current collector caused by electrode separation during the charging or discharging process.

[0275] Although not shown in Table 2, compared with the all-solid-state secondary battery of Example 8, the life characteristics of the all-solid-state secondary battery of Reference Example 3 deteriorate.

[0276] Evaluation Example 4: Evaluation of high-rate characteristics The high-rate characteristics of each all-solid-state secondary battery fabricated in Examples 1 to 6, Comparative Example 1, and Reference Example 1 were evaluated through the following charge / discharge tests. The charge / discharge tests were conducted by placing the all-solid-state secondary batteries in a thermostat at a temperature of 45°C.

[0277] The all-solid-state secondary batteries of Examples 1 to 6, Comparative Example 1, and Reference Example 1 were each charged at a constant current rate of 0.1C at a temperature of 45°C until the voltage reached 3.9V (vs. Li), and then, in the constant voltage mode, while maintaining 3.9V, the charging was cut off at a current rate of 0.05C. Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.1C until the voltage reached 2.5V (vs. Li) (formation cycle).

[0278] The all-solid-state secondary batteries that had undergone the formation cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 3.9V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.2C until the voltage reached 2.5V (vs. Li) (first cycle).

[0279] The all-solid-state secondary batteries that had undergone the first cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 3.9V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.33C until the voltage reached 2.5V (vs. Li) (second cycle).

[0280] The all-solid-state secondary batteries that had undergone the second cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 3.9V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.5C until the voltage reached 2.5V (vs. Li) (third cycle).

[0281] The all-solid-state secondary batteries that had undergone the third cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 3.9V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 1.0C until the voltage reached 2.5V (vs. Li) (fourth cycle).

[0282] After each charge / discharge cycle, the all-solid-state secondary batteries were left to stand for 10 minutes. Some of the charge / discharge test results at a temperature of 45°C are shown in Table 2. The high-rate characteristics are defined by Equation 1.

[0283] The high-rate characteristics of each all-solid-state secondary battery of Example 7, Comparative Example 2, and Reference Example 2 were evaluated through the following charge / discharge tests. The charge / discharge tests were conducted by placing the all-solid-state secondary batteries in a thermostat at a temperature of 45°C.

[0284] The all-solid-state secondary batteries of Example 7, Comparative Example 2, and Reference Example 2 were each charged at a constant current rate of 0.1C at a temperature of 45°C until the voltage reached 2.5V (vs. Li). Then, in the constant voltage mode, while maintaining 2.5V, the charging was cut off at a current rate of 0.05C. Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.1C until the voltage reached 0.3V (vs. Li) (formation cycle).

[0285] The all-solid-state secondary batteries that had undergone the formation cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 2.5V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.2C until the voltage reached 0.3V (vs. Li) (first cycle).

[0286] The all-solid-state secondary batteries that had undergone the first cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 2.5V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.33C until the voltage reached 0.3V (vs. Li) (second cycle).

[0287] The all-solid-state secondary batteries that had undergone the second cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 2.5V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 0.5C until the voltage reached 0.3V (vs. Li) (third cycle).

[0288] The all-solid-state secondary batteries that had undergone the third cycle were each charged at a constant current rate of 0.2C at a temperature of 45°C until the voltage reached 2.5V (vs. Li). Subsequently, during discharge, the all-solid-state secondary batteries were each discharged at a constant current rate of 1.0C until the voltage reached 0.3V (vs. Li) (fourth cycle).

[0289] After each charge / discharge cycle, the all-solid-state secondary batteries were left to stand for 10 minutes. Some of the charge / discharge test results at a temperature of 45°C are shown in Table 2. The high-rate characteristics are defined by Equation 1.

[0290] Equation 1 High-rate characteristic (%) = [Discharge capacity of the 4th cycle / Discharge capacity of the formation cycle] × 100 Table 3

[0291] As shown in Table 3, compared with the all-solid-state secondary battery of Comparative Example 1, the high-rate characteristics of each of the all-solid-state secondary batteries of Examples 1 to 6 are improved.

[0292] In each of the all-solid-state secondary batteries of Examples 1 to 6, the first negative electrode active material layer includes the first negative electrode active material, the second negative electrode active material, and a fibrous carbon-based material in parallel (e.g., simultaneously), so that although the volume of the first negative electrode active material layer changes during charging or discharging, an increase in the internal resistance of the first negative electrode active material layer is suppressed or reduced, and the uniformity of the electrode reaction is also improved, thereby improving the high-rate characteristics compared with the all-solid-state secondary battery of Comparative Example 1.

[0293] Compared with the all-solid-state secondary battery of Comparative Example 2, the high-rate characteristics of the all-solid-state secondary battery of Example 7 are improved.

[0294] In the all-solid-state secondary battery of Example 7, the first negative electrode active material layer includes the first negative electrode active material, the second negative electrode active material, and a fibrous carbon-based material in parallel (e.g., simultaneously), so that although the volume of the first negative electrode active material layer changes during charging or discharging, an increase in the internal resistance of the first negative electrode active material layer is suppressed or reduced, and the uniformity of the electrode reaction is also improved, thereby improving the high-rate characteristics compared with the all-solid-state secondary battery of Comparative Example 2.

[0295] According to one or more aspects of the embodiments of the present disclosure, an all-solid-state secondary battery can be provided in which a fibrous carbon-based material and a binder are included in a first negative electrode active material layer having an initial charge capacity lower than that of the positive electrode active material layer, thereby improving the cycle characteristics and suppressing or reducing volume changes during charging or discharging.

[0296] In the context of the present disclosure and unless otherwise defined, the term "use" and its variants can be considered to be synonymous with the term "utilize" and its variants, respectively.

[0297] As used herein, the terms "substantially", "about" and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations of measured or calculated values recognized by one of ordinary skill in the art. As used herein, "about" or "approximately" also includes the recited value and means within an acceptable variation from the particular value as determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10% or ±5% of the recited value.

[0298] Any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, the range "1.0 to 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including the recited minimum value of 1.0 and the recited maximum value of 10.0), that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as for example 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations therein. Accordingly, the applicant reserves the right to modify this specification and the claims to expressly recite any sub-ranges that are subsumed within the ranges expressly recited herein.

[0299] Any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware can be utilized to implement the battery module, battery pack, battery management system, electric vehicle, and / or any other related devices or components in accordance with embodiments of the present disclosure described herein. For example, the various components of the device can be formed on a single integrated circuit (IC) chip or on separate IC chips. Additionally, the various components of the device can be implemented on a flexible printed circuit film, tape carrier package (TCP), printed circuit board (PCB), or formed on a substrate. Further, the various components of the device can be processes or threads running on one or more processors in one or more computing devices that execute computer program instructions and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which can be implemented in the computing device using a standard memory device (such as, by way of example, random access memory (RAM)). The computer program instructions can also be stored in other non-transitory computer-readable media (such as, by way of example, CD-ROM, flash drive, etc.). Moreover, those skilled in the art should recognize that, without departing from the scope of the present disclosure, the functions of various computing devices can be combined or integrated into a single computing device, or the functions of a particular computing device can be distributed across one or more other computing devices.

[0300] It should be understood that the embodiments described herein should be considered only in a descriptive sense and not for purposes of limitation. The description of features or aspects within each embodiment should generally be considered available for other similar features or aspects in one or more other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand that one or more suitable changes in form and detail can be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. An all-solid-state secondary battery, comprising: positive electrode layer; Negative electrode layer; as well as a solid electrolyte layer, between the positive electrode layer and the negative electrode layer, The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on one side of the positive electrode current collector, and The negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer on one side of the negative electrode current collector, The first negative electrode active material layer includes: a first negative electrode active material and a second negative electrode active material, both of which can form an alloy or a compound with lithium; and a fibrous carbon material. The ratio B / A of the initial charge capacity B of the first negative electrode active material layer to the initial charge capacity A of the positive electrode active material layer is in the range of 0.01 to 0.75, The initial charge capacity of the positive electrode active material layer is charged from the first open circuit voltage to the maximum charge voltage vs. Li / Li + to determine, and The initial charge capacity of the first negative electrode active material layer is charged from the second open circuit voltage to a voltage of 0.01 V vs. Li / Li + to be sure.

2. The all-solid-state secondary battery according to claim 1, wherein: The first negative electrode active material in the form of particles has a size of 2 μm or less and an aspect ratio of 5 or less.

3. The all-solid-state secondary battery according to claim 2, wherein: The first negative electrode active material includes a first metal negative electrode active material, and the first metal negative electrode active material includes silicon, gold, platinum, palladium, silver, aluminum, bismuth, tin, zinc or a combination thereof.

4. The all-solid-state secondary battery according to claim 1, wherein: The size of the first negative electrode active material is smaller than the length of the fibrous carbon material, and A ratio of a size of the first negative electrode active material or a size of the second negative electrode active material to a length of the fibrous carbon-based material is in a range of 1:10 to 1:2,000.

5. The all-solid-state secondary battery according to claim 1, wherein: The fibrous carbon material is a conductive carbon material. The aspect ratio of the fibrous carbon-based material is 10 or more, and The fibrous carbon-based material includes an amorphous fibrous carbon-based material, a crystalline fibrous carbon-based material, or a combination thereof.

6. The all-solid-state secondary battery according to claim 1, wherein: The fibrous carbon-based material includes a fibrous carbon nanostructure, and the fibrous carbon nanostructure includes a carbon nanotube, a carbon nanofiber, a carbon nanobelt, or a combination thereof.

7. The all-solid-state secondary battery according to claim 6, wherein: The carbon nanotubes include a carbon nanotube primary structure, a carbon nanotube secondary structure including a plurality of carbon nanotube primary structures, or a combination thereof, and The carbon nanotube primary structure is a single carbon nanotube unit.

8. The all-solid-state secondary battery according to claim 7, wherein: The carbon nanotube primary structure includes single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes or a combination thereof, and has a diameter of 1 nm to 20 nm and a length of 100 nm to 2 μm, and The carbon nanotube secondary structure includes bundle-type carbon nanotubes, rope-type carbon nanotubes, or a combination thereof, and has a diameter of 2 nm to 50 nm and a length of 500 nm to 1,000 μm.

9. The all-solid-state secondary battery according to claim 1, wherein: The second negative electrode active material in the form of particles has a size of less than 1 μm and an aspect ratio of 5 or less, and includes a carbon-based negative electrode active material, a second metal-based negative electrode active material different from the first negative electrode active material, or a combination thereof, The carbon-based negative electrode active material includes amorphous carbon, crystalline carbon, porous carbon or a combination thereof, and The second metal negative electrode active material includes gold, platinum, palladium, silver, aluminum, bismuth, tin, zinc or a combination thereof.

10. The all-solid-state secondary battery according to claim 1, wherein: The second negative electrode active material includes a mixture of first particles composed of amorphous carbon and second particles composed of a second metal-based negative electrode active material, and Wherein, relative to 100wt% of the total weight of the mixture, the content of the second particles is in the range of 1wt% to 60wt%.

11. The all-solid-state secondary battery according to claim 1, wherein: The second negative electrode active material includes a composite negative electrode active material, and The composite negative electrode active material comprises: a carbon support; and a metal negative electrode active material supported on the carbon support. The metal-based negative electrode active material includes a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof, and is in the form of particles with a particle size of 1 nm to 200 nm, and The carbon-based support is in the form of particles and has a particle size of 10 nm to 2 μm.

12. The all-solid-state secondary battery according to claim 1, wherein: The first negative electrode active material layer includes a binder, The binder comprises a polymer binder and / or a fluorine-based binder, and The content of the binder is in a range of 0.1 parts by weight to 20 parts by weight relative to 100 parts by weight of the mixture of the first negative electrode active material and the second negative electrode active material.

13. The all-solid-state secondary battery according to claim 1, wherein: The thickness of the first negative electrode active material layer is 50% or less of the thickness of the positive electrode active material layer, and The first negative electrode active material layer has a thickness of 1 μm to 50 μm.

14. The all-solid-state secondary battery according to claim 1, further comprising a second negative electrode active material layer between the negative electrode current collector and the first negative electrode active material layer and / or between the negative electrode current collector and the solid electrolyte layer, in, The second negative electrode active material layer is a metal layer, The metal layer includes lithium or a lithium alloy, and The second negative electrode active material layer is thinner than the first negative electrode active material layer.

15. The all-solid-state secondary battery according to claim 1, wherein: The positive electrode active material layer includes a positive electrode active material, The positive electrode active material includes a sulfide positive electrode active material, an oxide positive electrode active material or a combination thereof. The sulfide-based positive electrode active material includes nickel sulfide, copper sulfide, Li2S, a composite containing Li2S, or a combination thereof. The oxide-based positive electrode active material includes lithium transition metal oxide, lithium-free metal oxide or a combination thereof. The lithium transition metal oxide includes lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium manganate, lithium iron phosphate or a combination thereof, and The lithium-free metal oxide includes iron oxide, vanadium oxide or a combination thereof.

16. The all-solid-state secondary battery according to claim 15, wherein: The Li2S-containing composite includes a composite of Li2S and a lithium salt, a composite of Li2S, a lithium salt and a conductive material, a composite of Li2S and a metal halide, a composite of Li2S, a metal halide and a conductive material, a composite of Li2S, a lithium salt and a metal halide, a composite of Li2S, a lithium salt, a metal halide and a conductive material, or a combination thereof. Li2S-Li complex of Li2S and lithium salt a X1 b represents, where 1≤a≤5 and 1≤b≤5, The composite of Li2S, lithium salt, metal halide and conductive material is composed of Li2S-Li a X1 b -C means, where 1≤a≤5 and 1≤b≤5, The complex of Li2S and metal halide is composed of Li2S-M c X2 d represents, where 1≤c≤5 and 1≤d≤5, The composite of Li2S, metal halide and conductive material is composed of Li2S-M c X2 d -C means, where 1≤c≤5 and 1≤d≤5, The complex of Li2S, lithium salt and metal halide is composed of Li2S-Li a X1 b -M c X2 d means, where 1≤a≤5, 1≤b≤5, 1≤c≤5, and 1≤d≤5, The composite of Li2S, lithium salt, metal halide and conductive material is composed of Li2S-Li a X1 b -M c X2 d -C means, where 1≤a≤5, 1≤b≤5, 1≤c≤5, and 1≤d≤5, X1 is I, Br, Cl, F, H, O, Se, Te, N, P, As, Sb, Al, B, OCl, PF6, BF4, SbF6, AsF6, ClO4, AlO2, AlCl4, NO3, CO3, BH4, SO4, BO3, PO4, NCl, NCl2, BN2 or a combination thereof, M is at least one metal selected from Group II to Group XV of the Periodic Table of Elements, and X2 is I, Br, Cl, F or a combination thereof.

17. The all-solid-state secondary battery according to claim 1, wherein: The positive electrode active material layer further comprises at least one selected from a solid electrolyte, a conductive material and a binder. The solid electrolyte includes a sulfide-based solid electrolyte, and The conductive material includes a carbon-based conductive material, and Wherein, the solid electrolyte layer comprises a solid electrolyte or a combination of a solid electrolyte and a gel electrolyte, The solid electrolyte includes a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte or a combination thereof, and The gel electrolyte includes a polymer gel electrolyte.

18. The all-solid-state secondary battery according to claim 17, wherein: The sulfide solid electrolyte includes a sulfide-based solid electrolyte selected from the group consisting of Li2S-P2S5, Li2S-P2S5-LiX, 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 , Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , Li 7-x PS 6-x Cl x , Li 7-x PS 6-x Br x and Li 7-x PS 6-x I x At least one of the above, or including a argyrodite-type solid electrolyte, wherein, in Li2S-P2S5-LiX, X is a halogen element, wherein, in Li2S-P2S5-Z m S n In which m and n are each positive numbers, and Z is selected from one of Ge, Zn and Ga, wherein in Li2S-SiS2-Li p MO q In the formula (a), p and q are each positive numbers, and M is selected from one of P, Si, Ge, B, Al, Ga and In, wherein in Li 7-x PS 6-x Cl x , 0≤x≤2, where Li 7-x PS 6-x Br x , 0≤x≤2, where Li 7- x PS 6-x I x In the equation, 0≤x≤2, The argyrodite-type solid electrolyte includes at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I, and has a density of 1.5 g / cc to 2.0 g / cc.

19. The all-solid-state secondary battery according to claim 1, wherein: At least one of the positive electrode current collector and the negative electrode current collector includes a base film and a metal layer on one side of the base film, wherein the base film comprises a polymer, the polymer comprises polyethylene terephthalate, polyethylene, polypropylene, polybutylene terephthalate, polyimide or a combination thereof, and The metal layer includes indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, lithium or alloys thereof.

20. The all-solid-state secondary battery according to claim 1, further comprising a first inert member on at least one of a side of the positive electrode collector facing away from the positive electrode active material layer and a side of the negative electrode collector facing away from the first negative electrode active material layer, in, The first inert member is an elastic member.

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