Subassembly for electrode-solid electrolyte, all-solid-state battery including the same, and method for preparing all

Abstract

A subassembly for an electrode-solid electrolyte, an all-solid-state battery including the same, and a method of making the all-solid-state battery. The electrode-solid electrolyte subassembly includes: an electrode including a porous current collector having a first side and an opposite second side; an elastic layer comprising an elastic polymer and disposed on the first side of the porous current collector; and a solid electrolyte disposed on the opposite second side of the porous current collector. The porous current collector includes a plurality of internal pores, and the elastomeric polymer is disposed in at least one of the plurality of internal pores of the porous current collector.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to and all benefits arising from Korean Patent Application No. 10 - 2023 - 0195606, filed with the Korean Intellectual Property Office on December 28, 2023, and incorporates its content herein by reference in its entirety. Technical field

[0003] The present disclosure relates to a sub - assembly for an electrode - solid electrolyte, a all - solid - state battery including the same, and a method of manufacturing the all - solid - state battery. Background art

[0004] All - solid - state batteries having a solid electrolyte in place of a flammable organic solvent electrolyte have been proposed to provide batteries with high energy density and improved safety.

[0005] In an all - solid - state battery, the thickness of the negative electrode active material layer typically varies during charging and discharging. Accordingly, the ion conduction path (channel) and the electron conduction path of the all - solid - state battery may be disrupted, resulting in deterioration of charging and discharging characteristics, such as Coulomb efficiency.

[0006] To address these problems during charging and discharging, attempts have been made to relieve the internal pressure that occurs during lithium deposition / desorption. For example, thick buffer layers may be included on each of the negative electrode and the positive electrode on the outside of the all - solid - state battery. However, such a change may increase the difficulty in achieving a high energy density due to an increase in the overall volume in the battery design of the all - solid - state battery.

[0007] Accordingly, there is still a need for a sub - assembly of an electrode - solid electrolyte having a structure that provides excellent contact between the electrode and the solid electrolyte and excellent charging / discharging characteristics, such as discharge capacity and life characteristics, and a method of manufacturing an all - solid - state battery including the same. Summary of the invention

[0008] Provided is a sub - assembly for an electrode - solid electrolyte that maintains excellent contact between a porous current collector and an electrode active material during charging, has a low interfacial resistance, and has excellent charging and discharging characteristics, such as discharge capacity and life characteristics.

[0009] Provided is an all - solid - state battery including the sub - assembly for an electrode - solid electrolyte.

[0010] Provided is a method of manufacturing the all - solid - state battery.

[0011] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the embodiments presented in the present disclosure.

[0012] According to one aspect of the present disclosure, a subassembly for an electrode-solid electrolyte includes: an electrode including a porous current collector having a first side and an opposite second side,

[0013] an elastic layer including an elastic polymer and disposed on the first side of the porous current collector, and

[0014] a solid electrolyte disposed on the opposite second side of the porous current collector,

[0015] wherein the porous current collector includes a plurality of internal pores, and the elastic polymer is disposed in at least one of the plurality of internal pores of the porous current collector.

[0016] According to an embodiment, based on the total volume of the porous current collector, the porous current collector may have a porosity of about 10 volume % to about 99 volume %, and may have an average pore diameter of about 0.1 micrometers (μm) to about 100 μm.

[0017] According to an embodiment, the porous current collector may be a three-dimensional porous current collector having a pore diameter S and a spacing I between two adjacent pores, and a ratio S / I of the pore diameter to the spacing may be about 0.1 to about 0.9.

[0018] According to an embodiment, a horizontal cross-sectional shape of at least one of the pores of the three-dimensional porous current collector may be circular, elliptical, triangular, square, rectangular, or hexagonal.

[0019] According to an embodiment, the porous current collector may include copper, nickel, silver, aluminum, stainless steel, titanium, iron, chromium, cobalt, or a combination thereof.

[0020] According to an embodiment, when measured according to DMA (Dynamic Mechanical Analysis), the elastic polymer may have a Young's modulus of about 1 megapascal (MPa) to about 50 MPa.

[0021] According to an embodiment, the elastic polymer may include a copolymer having at least one hard structural unit and at least one soft structural unit, and

[0022] a weight ratio of the hard structural unit to the soft structural unit may be about 0.1 to 1.

[0023] According to an embodiment, the hard structural unit may include a styrene structural unit, a urethane structural unit, an ether structural unit, or a combination thereof, and the soft structural unit may include an ethylene structural unit, a propylene structural unit, a butylene structural unit, an isobutylene structural unit, a butadiene structural unit, an isoprene structural unit, or a combination thereof.

[0024] According to an embodiment, the elastic polymer may include styrene-butadiene rubber (SBR), styrene-ethylene-butene-styrene (SEBS) rubber, styrene-ethylene-propylene-styrene (SEPS) rubber, styrene-butadiene-styrene (SBS) rubber, styrene-isoprene-styrene (SIS) rubber, styrene-isobutylene-styrene (SIBS) rubber, or a combination thereof.

[0025] According to an embodiment, based on the total volume of the plurality of internal pores of the porous current collector, the elastic polymer may be provided in the plurality of internal pores in an amount of about 10% to about 90% by volume.

[0026] According to an embodiment, the elastic polymer may be provided in the plurality of internal pores with a concentration gradient decreasing in a direction from the first side of the porous current collector to the opposite second side, and based on the total volume of the plurality of internal pores of the porous current collector, the elastic polymer may be provided in the plurality of internal pores in an amount of about 55% to about 85% by volume.

[0027] According to an embodiment, the elastic polymer may further include an electron-conducting material having a conductivity of at least 10 -2 Siemens / cm.

[0028] According to an embodiment, the electron-conducting material may include carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanoparticles, or a combination thereof.

[0029] According to an embodiment, the electrode-solid electrolyte subassembly may further include a metal layer disposed between the first side of the porous current collector and the elastic layer.

[0030] According to an embodiment, an intermediate layer may be disposed between the opposite second side of the porous current collector and the solid electrolyte, and the intermediate layer may include a mixture of one or more of a carbon-containing material, a metal or a metalloid and a carbon-containing material, a composite of one or more of a metal or a metalloid and a carbon-containing material, or a combination thereof.

[0031] According to an embodiment, the carbon-containing material may include amorphous carbon, and the metals and metalloids may include indium, silicon, gallium, tin, aluminum, titanium, zirconium, niobium, germanium, antimony, bismuth, gold, platinum, palladium, magnesium, silver, zinc, nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0032] According to an embodiment, the thickness of the elastic layer may be about 10 micrometers (μm) to about 100 micrometers.

[0033] According to an embodiment, the combined thickness of the porous current collector and the elastic layer may be from about 20 μm to about 100 μm.

[0034] According to another aspect of the present disclosure, a all-solid-state battery includes: the electrode-solid electrolyte subassembly, wherein the electrode is a negative electrode; and a positive electrode, wherein the solid electrolyte is interposed between the negative electrode and the positive electrode.

[0035] According to another aspect of the present disclosure, a method of manufacturing a all-solid-state battery includes: providing a porous current collector having a first side and an opposite second side, wherein the porous current collector includes a plurality of internal pores; disposing a composition containing an elastic polymer on the first side of the porous current collector to form a coated current collector; drying the coated current collector to form an elastic layer including the elastic polymer and disposed on the first side of the porous current collector to prepare a porous current collector-elastic layer electrode including the elastic polymer, wherein the elastic polymer is disposed in at least one of the plurality of internal pores, and the porous current collector-elastic layer electrode is a negative electrode; providing a solid electrolyte; disposing the solid electrolyte on the opposite second side of the porous current collector of the porous current collector-elastic layer electrode to prepare an electrode-solid electrolyte subassembly; and disposing a positive electrode on the opposite side of the electrode-solid electrolyte subassembly to the solid electrolyte of the porous current collector to prepare the all-solid-state battery.

[0036] According to an embodiment, the step of providing the porous current collector may be performed using laser drilling or punching.

[0037] According to an embodiment, after the step of preparing the porous current collector-elastic layer electrode, the method may further include a step of disposing an intermediate layer on the opposite second side of the porous current collector, wherein the intermediate layer may include a mixture of one or more of a carbon-containing material, a metal or a metalloid and a carbon-containing material, a composite of one or more of a metal or a metalloid and a carbon-containing material, or a combination thereof.

[0038] According to an embodiment, the solid electrolyte may have been surface-treated.

[0039] According to an embodiment, before disposing the composition containing the elastic polymer on the first side of the porous current collector, the method may further include disposing a metal layer on the first side of the porous current collector.

[0040] According to an embodiment, a method of fabricating an electrode-solid electrolyte subassembly includes: providing a porous current collector having a first side and an opposite second side, wherein the porous current collector includes a plurality of internal pores; disposing a composition containing an elastic polymer on the first side of the porous current collector to form a coated current collector; drying the coated current collector to form an elastic layer including the elastic polymer and disposed on the first side of the porous current collector to prepare a porous current collector-elastic layer electrode including the elastic polymer, wherein the elastic polymer is disposed in at least one of the plurality of internal pores; providing a solid electrolyte; and disposing the solid electrolyte on the opposite second side of the porous current collector of the porous current collector-elastic layer electrode to prepare an electrode-solid electrolyte subassembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other aspects, features, and advantages of some embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0042] Figure 1 is a schematic diagram of an embodiment of a subassembly for an electrode-solid electrolyte;

[0043] Figure 2 is a schematic diagram of an embodiment of a subassembly for an electrode-solid electrolyte;

[0044] Figure 3 is a top view of an embodiment of a porous current collector;

[0045] Figure 4 is a schematic diagram of an embodiment of a all-solid-state secondary battery including a subassembly for an electrode-solid electrolyte;

[0046] Figure 5A and 5B are respectively scanning electron microscope photographs of three-dimensional porous negative current collectors of negative electrode-solid electrolyte subassemblies obtained by disassembling the all-solid-state secondary batteries prepared in Example 1 and Example 2;

[0047] Figure 6A is a graph of the imaginary impedance (ohm-square centimeter, Ω cm 2 ) versus the real impedance (ohm-square centimeter, Ω cm 2 ) for the all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2;

[0048] Figure 6B is for Figure 6A the imaginary impedance (ohm-square centimeter, Ω cm 2 ) versus the real impedance (ohm-square centimeter, Ω cm2 ) graph;

[0049] Figure 7A Graph of voltage (volts) vs. capacity per unit area (milliamperes-hour per square centimeter, mAh / cm 2 ) for the charge / discharge test results of the all-solid-state secondary battery prepared in Example 1;

[0050] Figure 7B Graph of voltage (volts) vs. capacity per unit area (milliamperes-hour per square centimeter, mAh / cm 2 ) for the charge / discharge test results of the all-solid-state secondary batteries prepared in Comparative Examples 1 and 2;

[0051] Figure 8 Graph of capacity per unit area (milliamperes-hour per square centimeter, mAh / cm 2 ) vs. cycle (number) for the charge / discharge test up to 40 cycles of the all-solid-state secondary batteries prepared in Example 1 and Comparative Example 1;

[0052] Figure 9A Optical microscope photograph at twice magnification of the surface of the three-dimensional porous negative electrode current collector of laser-drilled copper foam (copper foam) in the all-solid-state secondary battery prepared in Example 1 before charging; and

[0053] Figure 9B and 9C Optical microscope photograph at twice magnification of the state of the surface of the three-dimensional porous negative electrode current collector of laser-drilled copper foam in the all-solid-state secondary battery as shown Figure 9A after the all-solid-state secondary battery is charged and discharged once at 0.2 C and disassembled as described in Evaluation Example 5. DETAILED DESCRIPTION

[0054] The embodiments will now be described in detail, examples of which are shown in the drawings, where like reference numerals always refer to like elements. In this regard, the present embodiments may have different forms and should not be construed as limited to the descriptions set forth herein. Accordingly, the embodiments are described below only by reference to the drawings to explain aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one (kind) of..." when before or after a list of elements modify the entire list of elements, rather than individual elements of the list.

[0055] In the following, since the inventive concept allows for various variations and numerous embodiments, the specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the inventive concept to a specific practice mode, and it will be understood that all variations, equivalents, and alternatives that do not depart from the spirit and technical scope are encompassed in the inventive concept.

[0056] The terms used herein are only for describing the specific embodiments and are not intended to limit the inventive concept. As used herein, the singular forms also include the plural forms, including "at least one (kind)", unless the context clearly indicates otherwise.

[0057] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element, or there may be an intermediate element therebetween. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element.

[0058] Expressions such as "at least one kind of...", "one or more kinds of...", or "one or more" when before or after a list of elements modify the entire list of elements, rather than individual elements of the list. As used herein, the term "combination" includes mixtures, alloys, reaction products, etc., unless otherwise specifically stated. As used herein, the term "comprising" means that other components (assemblies) may be further included, rather than excluding other components (assemblies), unless otherwise specifically stated. In this specification, terms such as "first", "second", etc. do not indicate order, quantity, or importance, but are used to distinguish one element from another. Unless otherwise indicated herein or clearly contradicted by the context, it should be construed to include both the singular and the plural. Unless otherwise specified, "or" means "and / or".

[0059] Throughout this specification, "an embodiment", "the embodiment", etc. may mean that the specific elements described with respect to the embodiment are included in at least one of the embodiments described herein, and may or may not be present in other embodiments. Additionally, it should be understood that the recited requirements may be combined in any suitable manner in various embodiments.

[0060] Unless otherwise specified, all percentages, parts, ratios, etc. are by weight. Additionally, when a quantity, concentration, or other value or parameter is given as a range, a preferred range, or a list of upper and lower preferred values, it will be understood that all ranges formed by any pair of any range upper limit or upper preferred value and any range lower limit or lower preferred value are specifically disclosed, whether or not the ranges are separately disclosed.

[0061] When stating a range of numerical values herein, unless otherwise stated, the range is intended to include the endpoints and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values recited when defining the range.

[0062] Unless otherwise specified, the unit "parts by weight" refers to the weight ratio between the corresponding components, and the unit "parts by mass" refers to the value obtained by converting the weight ratio between the corresponding components into the solid content.

[0063] In addition, relative terms such as "lower" or "bottom" and "upper" or "top" may be used herein to describe the relationship of one element to another as shown in the figures. It will be understood that relative terms are intended to cover different orientations of the device in addition to the orientation described in the figures. For example, if the device in one of the figures is flipped, an element described as being on the "lower" side of another element will be oriented on the "upper" side of the other element. Thus, the term "lower" can cover both the "lower" and "upper" orientations, depending on the specific orientation of the figure. Similarly, if the device in one of the figures is flipped, an element described as "beneath" or "under" another element will be oriented "above" the other element. Thus, the terms "beneath" or "under" can cover both the above and below orientations.

[0064] As used herein, "about" includes the stated value and means within an acceptable deviation range of the specific value determined by one of ordinary skill in the art in view of the measurements discussed and the errors associated with the measurement of the specific quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, 20%, 10%, or 5%.

[0065] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Additionally, it will be understood that terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with their meaning in the context of this disclosure and the relevant art, and should not be interpreted as idealized. Additionally, it should not be interpreted in an overly formal sense.

[0066] Unless otherwise defined, an elastic layer refers to a material that includes a property of changing volume and shape when a force is applied to an object and then returning to its original shape when the force is removed.

[0067] Unless otherwise defined, an internal hole refers to a hole located inside an object or material.

[0068] Exemplary embodiments are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments. As a result, for example, due to manufacturing techniques and / or tolerances, the illustrated shapes may vary. Accordingly, the embodiments described herein should not be construed as limited to the specific shapes of the regions described herein, but should include, for example, deviations in shape that occur during manufacturing. For example, regions illustrated or described as flat may generally have rough and / or non-linear features. Additionally, sharp corners illustrated may be rounded. Thus, the regions shown in the figures are schematic in nature, and the shapes are not intended to illustrate the exact shape of the regions or to limit the scope of the claims.

[0069] As is well known, a buffer layer for a subassembly of an electrode - solid electrolyte is positioned on both sides of a current collector, positioned to surround the current collector, or positioned on the surface of an electrode in contact with the solid electrolyte. However, in the design of the buffer layer, the internal pressure generated during the operation of a all - solid - state battery is not uniform, which reduces the charge and discharge characteristics. At the same time, the thickness of the battery can change, increasing the difficulty in achieving a high energy density.

[0070] In addition, a all - solid - state battery having a "lithium - free" (or anode - free) structure in an initial or fully discharged state undergoes repeated lithium deposition and lithium desorption processes during charging and discharging. As a result, voids can form between the anode and the solid electrolyte layer, and the interfacial resistance can increase.

[0071] A subassembly for an electrode - solid electrolyte, a all - solid - state battery including the same, and a method for manufacturing the all - solid - state battery that solve the above problems are disclosed.

[0072] The subassembly for an electrode - solid electrolyte, the all - solid - state battery including the same, and the method for manufacturing the all - solid - state battery will be described in more detail by way of exemplary embodiments.

[0073] Subassembly 100 for an electrode - solid electrolyte

[0074] Figure 1 is a schematic view of a subassembly for an electrode - solid electrolyte 100 according to one embodiment. Figure 2 is a schematic view of a subassembly for an electrode - solid electrolyte 100 according to another embodiment.

[0075] Figure 1 and 2The electrode-solid electrolyte subassembly 100 shown in [Figure 0] has a "lithium-free" structure in the initial state or fully discharged state. The electrode-solid electrolyte subassembly 100 according to an embodiment may be a negative electrode-solid electrolyte subassembly. The negative electrode 40 may include a porous current collector 20 having a first side (opposite to the solid electrolyte) and an opposite second side (solid electrolyte side), and an elastic layer 21 including an elastic polymer 23 and disposed on the first side of the porous current collector 20, and the elastic polymer 23 may be disposed in at least one of a plurality of internal pores 22 of the porous current collector 20. The solid electrolyte 30 may be disposed on the opposite second side of the porous current collector 20.

[0076] Based on the total volume of the porous current collector, the porous current collector 20 according to an embodiment may have a porosity of about 10% to about 99%, and an average pore diameter of about 0.1 μm to 100 μm. For example, based on the total volume of the porous current collector, the porous current collector 20 may have a porosity of about 15 vol% to about 90 vol%, about 20 vol% to about 85 vol%, about 25 vol% to about 80 vol%, or about 30 vol% to about 80 vol%, and an average pore diameter of about 0.1 μm to about 100 μm, about 0.5 μm to about 100 μm, about 0.8 μm to about 100 μm, about 1 μm to about 90 μm, about 1 μm to about 80 μm, about 1 μm to about 70 μm, about 1 μm to about 60 μm, about 1 μm to about 50 μm, about 5 μm to about 40 μm, or about 8 μm to about 30 μm. When the porosity and average pore diameter of the porous current collector 20 are within the above ranges, the deposition / desorption of lithium from the negative electrode during charging and discharging of the all-solid-state battery is easy, and lithium can be uniformly deposited into the pores.

[0077] In this specification, when the cross-sectional shape of the pore is spherical (circular), the average pore diameter refers to the average pore diameter S as shown in [Figure 6]. If the pore is not spherical, the average pore diameter refers to the length of the major axis. In an embodiment of the present disclosure, the average pore diameter can be measured by using the Brunauer-Emmett-Teller (BET) method. The BET method is disclosed in Brunauer, Stephen; Emmett, P. H.; Teller, Edward (1938). "Adsorption of Gases in Multimolecular Layers," Journal of the American Chemical Society. 60 (2): 309-319, and this reference is incorporated into the present disclosure. Additionally, the average pore diameter can also be evaluated by image analysis using a scanning electron microscope method. Figure 3 shown in [Figure 8].

[0078] The porous current collector 20 according to an exemplary embodiment is a three-dimensional porous current collector and may have a patterned pore spacing, which has a pore diameter S (e.g., an average pore diameter) and a spacing I between two adjacent pores, and the ratio S / I of the pore diameter to the spacing may be 0.1 to 0.9, 0.1 to 0.8, 0.1 to 0.7, 0.1 to 0.6, 0.2 to 0.5, 0.25 to 0.5, or 0.4 to 0.5. For example, the distance I between two adjacent pores means the distance between the centers of two adjacent pores. For example, the porous current collector 20 may have a regular pattern, which has a pore diameter S and a spacing I between two adjacent pores. For example, each of the pores may have the shape of a through hole. Compared with a two-dimensional porous current collector, the three-dimensional porous current collector may have a higher volume fraction of electrode active material and a larger reaction area, and thus may increase the capacity and energy density of an all-solid-state battery containing the same. If the ratio S / I of the pore diameter of the porous current collector 20 to the spacing between the pores is within the above range, excellent contact can be maintained between the porous current collector and the negative electrode active material (during charging), thereby providing an all-solid-state battery having a low interfacial resistance and excellent charge and discharge characteristics.

[0079] In the porous current collector 20 according to an exemplary embodiment, the horizontal cross-sectional shape of at least one of the pores 22 of the three-dimensional porous current collector may be circular, elliptical, triangular, square, rectangular, or hexagonal. However, the horizontal cross-sectional shape of the pores 22 of the three-dimensional porous current collector is not limited thereto.

[0080] The porous current collector 20 according to an exemplary embodiment may include copper, nickel, silver, aluminum, stainless steel, titanium, iron, chromium, cobalt, or a combination thereof. The porous current collector 20 may be made of an alloy or mixture of one or two or more of the above-listed metals. However, the material for the porous current collector 20 is not limited thereto, and any material used as an electrode current collector in the related art may be used.

[0081] The thickness of the porous current collector 20 according to an exemplary embodiment may be, but is not limited to, for example, 5 μm to 100 μm, 10 μm to 100 μm, or 10 μm to 50 μm. If the thickness of the porous current collector 20 is within the above-exemplified range, an all-solid-state battery having improved energy density and life characteristics can be provided.

[0082] When measured according to DMA (Dynamic Mechanical Analysis), the elastic polymer according to an exemplary embodiment may have a Young's modulus of 1 MPa to 50 MPa. The elastic polymer 23 may have stretchability that stretches in a predetermined direction and then returns. Additionally, the elastic polymer 23 may flexibly respond to an external force applied from a certain direction. The all-solid-state battery including the elastic polymer 23 may flexibly respond to changes in thickness during charging and discharging, promoting lithium deposition / desorption. In an embodiment, the all-solid-state battery does not contain a thick external material, which may provide a high energy density.

[0083] Examples of the elastic polymer 23 may be a thermoplastic elastomer, a thermosetting elastomer, or a combination thereof, and may include a plurality of identical or different structural units.

[0084] The elastic polymer 23 according to an exemplary embodiment may be a thermoplastic elastomer. For example, the thermoplastic elastomer may include a copolymer having at least one hard structural unit providing relatively hard properties and at least one soft structural unit providing relatively soft properties. The hard structural unit may provide plastic properties such as high-temperature performance, thermoplastic processability, tensile strength, and tear strength. The soft structural unit may provide elastic properties such as low-temperature performance, hardness, flexibility, and tension / compression. Within the elastic polymer, the hard structural units and soft structural units may be arranged alternately or in clusters or blocks.

[0085] In the elastic polymer 23 according to an exemplary embodiment, the weight ratio of the hard structural unit to the soft structural unit may be 0.1 to 1. Alternatively, the elastic polymer 23 may have an amount of soft structural units of 50 weight percent (wt%) or more of the total weight of the soft structural unit and the hard structural unit. When the weight ratio of the hard structural unit to the soft structural unit of the elastic polymer 23 is within the above range, the all-solid-state battery including it may flexibly respond to changes in thickness during charging and discharging, promote lithium deposition / desorption, and may have excellent charging and discharging characteristics.

[0086] The hard structural unit according to an exemplary embodiment may include a styrene structural unit, a urethane structural unit, an ether structural unit, or a combination thereof.

[0087] The soft structural unit according to an exemplary embodiment may include an ethylene structural unit, a propylene structural unit, a butylene structural unit, an isobutylene structural unit, a butadiene structural unit, an isoprene structural unit, or a combination thereof.

[0088] For example, the hard structural unit may be a styrene structural unit, and the soft structural unit may include an ethylene structural unit, a propylene structural unit, a butylene structural unit, an isobutylene structural unit, a butadiene structural unit, an isoprene structural unit, or a combination thereof.

[0089] The elastic polymer 23 according to an exemplary embodiment may include styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene (SEBS) rubber, styrene-ethylene-propylene-styrene (SEPS) rubber, styrene-butadiene-styrene (SBS) rubber, styrene-isoprene-styrene (SIS) rubber, styrene-isobutylene-styrene (SIBS) rubber, or a combination thereof. For example, the elastic polymer 23 may include styrene-ethylene-butylene-styrene (SEBS) rubber, styrene-ethylene-propylene-styrene (SEPS) rubber, styrene-butadiene-styrene (SBS) rubber, or a combination thereof.

[0090] Based on the total volume of the plurality of internal pores of the porous current collector, the elastic polymer 23 according to an exemplary embodiment may be provided in at least one of the plurality of internal pores of the porous current collector 20 in an amount of about 10% by volume to about 90% by volume, about 15% by volume to about 89% by volume, about 20% by volume to about 88% by volume, about 25% by volume to about 88% by volume, about 30% by volume to about 87% by volume, about 35% by volume to about 86% by volume, about 40% by volume to about 86% by volume, about 45% by volume to about 86% by volume, or about 50% by volume to about 85% by volume. Within the range of the volume percentage of the filling of the internal pores of the porous current collector 20, the elastic polymer 23 can maintain excellent contact between the porous current collector and the electrode active material during charging, thereby providing a all-solid-state battery with low interfacial resistance and excellent charge and discharge characteristics. If the elastic polymer 23 is not provided in at least one of the plurality of internal pores of the porous current collector 20, the all-solid-state battery including it may not be able to flexibly respond to the change of the internal pressure during charging and discharging, making it difficult to deposit / desorb lithium.

[0091] The porous current collector 20 according to an exemplary embodiment may be filled (e.g., provided) with the elastic polymer 23 in the plurality of internal pores with a concentration gradient decreasing from the first side (opposite to the solid electrolyte) to the opposite second side (solid electrolyte side). Based on the total volume of the plurality of internal pores 22 of the porous current collector 20, at least one of the plurality of internal pores may be filled with 55% by volume to 85% by volume. The concentration of the elastic polymer 23 in the concentration gradient may decrease in the direction from the first side of the porous current collector 20 to the opposite second side. When the elastic polymer 23 is sequentially filled from the opposite second side (solid electrolyte side) of the porous current collector 20 to the first side (opposite side of the solid electrolyte), the elastic polymer 23 may act as an insulator to prevent electrons from passing through it, and thus the charge and discharge characteristics of the all-solid-state battery including it may deteriorate.

[0092] According to an embodiment, the elastic polymer 23 may further include an electronically conductive material. As used herein, an "electronically conductive" material or alternatively a "conductive" material refers to a material that conducts electricity. For example, the electronically conductive material may have at least 10 -2 The electronic conductive material may form a blend or composite with the elastic polymer 23. For example, the electronic conductive material may include carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanoparticles, or a combination thereof. For example, the electronic conductive material may include an electronic conductive polymer. Examples of the electronic conductive polymer may include poly(fluorene), polyphenylene, polypyrene, polyazulene, polynaphthalene, polyacetylene (PAC), poly(p-phenylene vinylene) (PPV), polypyrrole (PPY), polycarbazole, polyindole, polyazepine, polyaniline (PANI), polythiophene (PT), poly(3,4-ethylenedioxythiophene) (PEDOT), or poly(p-phenylene sulfide) (PPS). The electronic conductive material may serve as a path for the movement of electric current and may be continuously connected by the elastic polymer 23 without being destroyed by external force or internal pressure. In addition, the electron conductive material may maintain contact with the electrode current collector and the electrode active material (during charging), and thus the charge and discharge characteristics of an all-solid-state battery including the electron conductive material, such as charge / discharge efficiency and cycle characteristics, may be further improved.

[0093] In accordance with an exemplary embodiment Figure 2 In the porous current collector 20, a metal layer 24 may be further included between the first side (opposite to the solid electrolyte) and the elastic layer 21. For example, the metal layer 24 may be made of a material that does not react with lithium, i.e., a material that does not form an alloy or compound. Examples of the metal layer 24 include aluminum, nickel, titanium, cobalt, stainless steel, or a combination thereof. During charging and discharging of the all-solid-state battery, the metal layer 24 may prevent excessive expansion of the elastic polymer 23 filled in the internal pores 22 of the porous current collector 20.

[0094] The metal layer 24 may be formed to a predetermined thickness. The metal layer 24 may be a deposition layer formed by thermal evaporation or may be a fine pattern having a predetermined width and length. Examples of the fine pattern may be islands, lines, or waves, but are not limited thereto.

[0095] According to an embodiment, an intermediate layer 25 may be further included between the second surface (solid electrolyte side) of the porous current collector 20 and the solid electrolyte 30, and the intermediate layer 25 may include a carbon-containing material; a mixture of one or more metals or metalloids and a carbon-containing material; a composite of one or more metals or metalloids and a carbon-containing material; or a combination thereof.

[0096] According to an embodiment, the carbon-containing material may include amorphous carbon, and the metals and metalloids may include indium, silicon, gallium, tin, aluminum, titanium, zirconium, niobium, germanium, antimony, bismuth, gold, platinum, palladium, magnesium, silver, zinc, nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or a combination thereof.

[0097] Examples of the amorphous carbon may include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, carbon nanotubes, or carbon nanofibers, and any one classified as amorphous carbon in the technical field of the present invention may be used.

[0098] The carbon-containing material may include voids therein. Even after discharging, the carbon-containing material may include voids therein. The carbon-containing material including voids may have reduced volume expansion during charging and discharging.

[0099] The metals and metalloids may be in the form of particles. The average particle diameter (D50) of the metals and metalloids may be about 4 μm or less, about 3 μm or less, about 2 μm or less, about 1 μm or less, or 0.5 μm or less. The lower limit of the average particle diameter (D50) is not particularly limited and may be not less than 10 nanometers (nm). The average particle diameter (D50) refers to the particle size value of the point on the particle size distribution curve corresponding to 100% of the particles: where 50% of the particles are smaller than the particle size value. The average particle diameter (D50) may be measured as follows: by a method known to those skilled in the art, such as by using a particle size analyzer, or by measuring the particles in a transmission electron microscope photograph or a scanning electron microscope photograph. Alternatively, measurement may be performed using a measurement device utilizing dynamic light scattering, data analysis may be performed to count the number of particles in each particle size range, and then the average particle diameter (D50) value may be calculated.

[0100] In the above mixtures and composites, the weight ratio of the carbon-containing material and the metal or metalloid may be adjusted within a range that provides desired characteristics of the all-solid-state battery.

[0101] The thickness of the intermediate layer 25 may be 10 nm to 10 μm, 100 nm to 10 μm, 200 nm to 10 μm, 300 nm to 10 μm, 400 nm to 10 μm, 500 nm to 10 μm, 1 μm to 10 μm, 1 μm to 9 μm, 1 μm to 8 μm, 2 μm to 7 μm, or 3 μm to 7 μm. When the thickness of the intermediate layer 25 is within this range, the charging and discharging characteristics of the all-solid-state battery, such as charge / discharge efficiency and cycle characteristics, may be improved.

[0102] The thickness of the elastic layer 21 according to an exemplary embodiment may be 10 μm to 80 μm.

[0103] The total thickness (e.g., combined thickness) of the porous current collector 20 and the elastic layer 21 according to an exemplary embodiment may be 20 μm to 100 μm. When the total thickness of the porous current collector 20 and the elastic layer 21 is within the above range, the energy density of the all-solid-state battery including the same can be increased, and charging and discharging characteristics such as charge / discharge efficiency and cycle characteristics can be improved.

[0104] The solid electrolyte 30 according to an exemplary embodiment may be an oxide solid electrolyte, a sulfide solid electrolyte, or a combination thereof. For example, the solid electrolyte 30 may be an oxide solid electrolyte.

[0105] The oxide solid electrolyte may be one or more of the following: Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), 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 a Ga 1-a ) x (Ti b Ge 1-b ) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ a ≤ 1, and 0 ≤ b ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, and Li 3+x La3M2O 12 (where M is Te, Nb, or Zr, and x is an integer in the range of 1 to 10). The solid electrolyte can be prepared by sintering or the like.

[0106] For example, the oxide solid electrolyte may be a garnet solid electrolyte. As used herein, garnet is a compound that can be called using the formula X3Y2(SiO4)3的 A silicate, where X is a divalent cation and Y is a trivalent cation. As used herein, the term "garnet solid electrolyte" means that the solid electrolyte is isostructural with garnet, such as Mg3Al2(SiO4)3.

[0107] Non-limiting examples of the garnet solid electrolyte may include an oxide represented by Formula 1 below:

[0108] Formula 1

[0109] (Li x M1 y )(M2) 3-δ (M3) 2-ω O 12-z X z

[0110] where in Formula 1, 3 ≤ x ≤ 8, 0 ≤ y < 2, -0.2 ≤ δ ≤ 0.2, -0.2 ≤ ω ≤ 0.2, and 0 ≤ z ≤ 2,

[0111] M1 is a monovalent cation, divalent cation, trivalent cation, or a combination thereof,

[0112] M2 is a monovalent cation, divalent cation, trivalent cation, or a combination thereof,

[0113] M3 is a monovalent cation, divalent cation, trivalent cation, tetravalent cation, pentavalent cation, hexavalent cation, or a combination thereof, and

[0114] X can be a monovalent anion, divalent anion, trivalent anion, or a combination thereof.

[0115] In Formula 1, examples of the monovalent cation may include Na, K, Rb, Cs, H, Fr, etc., and examples of the divalent cation may include Mg, Ca, Ba, Sr, etc. Examples of the trivalent cation may include In, Sc, Cr, Au, B, Al, Ga, etc., and examples of the tetravalent cation may include Sn, Ti, Mn, Ir, Ru, Pd, Mo, Hf, Ge, V, Si, etc. Additionally, examples of the pentavalent cation may include Nb, Ta, Sb, V, P, etc.

[0116] For example, M1 can be hydrogen (H), iron (Fe), gallium (Ga), aluminum (Al), boron (B), beryllium (Be), or a combination thereof. M2 can be lanthanum (La), barium (Ba), calcium (Ca), strontium (Sr), yttrium (Y), bismuth (Bi), praseodymium (Pr), neodymium (Nd), actinium (Ac), samarium (Sm), gadolinium (Gd), or a combination thereof, and M3 can be zirconium (Zr), hafnium (Hf), tin (Sn), niobium (Nb), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), tungsten (W), tantalum (Ta), magnesium (Mg), technetium (Tc), ruthenium (Ru), palladium (Pd), iridium (Ir), scandium (Sc), cadmium (Cd), indium (In), antimony (Sb), tellurium (Te), thallium (Tl), platinum (Pt), silicon (Si), aluminum (Al), or a combination thereof.

[0117] In Formula 1, the monovalent anion used as X can be a halogen atom, a pseudohalogen, or a combination thereof, and the divalent anion can be S 2- or Se 2- , and the trivalent anion can be, for example, N 3- .

[0118] In Formula 1, 3 ≤ x ≤ 8, 3.3 ≤ x ≤ 8, 3.6 ≤ x ≤ 8, 6.7 ≤ x ≤ 7.5, or 6.8 ≤ x ≤ 7.1.

[0119] Non-limiting examples of the garnet solid electrolyte can include oxides represented by the following Formula 2:

[0120] Formula 2

[0121] (Li x M1 y )(La a1 M2 a2 ) 3-δ (Zr b1 M3 b2 ) 2-ω O 12-z X z

[0122] wherein in Formula 2, M1 is hydrogen (H), iron (Fe), gallium (Ga), aluminum (Al), boron (B), beryllium (Be), or a combination thereof,

[0123] M2 is barium (Ba), calcium (Ca), strontium (Sr), yttrium (Y), bismuth (Bi), praseodymium (Pr), neodymium (Nd), actinium (Ac), samarium (Sm), gadolinium (Gd), or a combination thereof,

[0124] M3 is hafnium (Hf), tin (Sn), niobium (Nb), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), molybdenum (Mo), tungsten (W), tantalum (Ta), magnesium (Mg), technetium (Tc), ruthenium (Ru), palladium (Pd), iridium (Ir), scandium (Sc), cadmium (Cd), indium (In), antimony (Sb), tellurium (Te), thallium (Tl), platinum (Pt), silicon (Si), aluminum (Al), or a combination thereof,

[0125] 3 ≤ x ≤ 8, 0 ≤ y < 2, -0.2 ≤ δ ≤ 0.2, -0.2 ≤ ω ≤ 0.2, 0 ≤ z ≤ 2,

[0126] a1 + a2 = 1, 0 < a1 ≤ 1, and 0 ≤ a2 < 1,

[0127] b1 + b2 = 1, 0 < b1 ≤ 1, and 0 ≤ b2 < 1, and

[0128] X can be a monovalent anion, a divalent anion, a trivalent anion, or a combination thereof.

[0129] In Formula 2, 6 ≤ x ≤ 8.

[0130] In Formula 2, the monovalent anion used as X can be a halogen atom, a pseudohalogen, or a combination thereof, and the divalent anion can be S 2- or Se 2- , and the trivalent anion can be, for example, N 3- .

[0131] In Formula 2, 3 ≤ x ≤ 8, 6.6 ≤ x ≤ 8, 6.7 ≤ x ≤ 7.5, or 6.8 ≤ x ≤ 7.1.

[0132] As used herein, the term "pseudohalogen" refers to a molecule comprising two or more electronegative atoms that exhibits properties similar to those of free halogen and produces an anion similar to a halide ion. Examples of the pseudohalogen can include cyanide (cyanide group), cyanate (cyanate group), thiocyanate (thiocyanate group), azide (azide group), or a combination thereof.

[0133] The halogen atom can be, for example, iodine (I), chlorine (Cl), bromine (Br), fluorine (F), or a combination thereof, and the pseudohalogen can be, for example, cyanide (cyanide group), cyanate (cyanate group), thiocyanate (thiocyanate group), azide (azide group), or a combination thereof.

[0134] The trivalent anion can be, for example, N 3- .

[0135] In Formula 2, M3 may be Al, Ga, In, Si, Ge, Sn, Sb, Bi, Sc, Y, Ti, Hf, V, Nb, Ta, W, or a combination thereof.

[0136] For example, the garnet solid electrolyte may be an oxide represented by the following Formula 3:

[0137] Formula 3

[0138] Li 3+x La3Zr 2-a M a O 12

[0139] wherein in Formula 3, M may be Al, Ga, In, Si, Ge, Sn, Sb, Bi, Sc, Y, Ti, Hf, V, Nb, Ta, W, or a combination thereof, x is a number from 1 to 10, and 0 ≤ a < 2.

[0140] The garnet solid electrolyte may include, for example, Li7La3Zr2O 12 , Li 6.5 La3Zr 1.5 Ta 0.5 O 12 etc.

[0141] Alternatively, the solid electrolyte may be, for example, a sulfide solid electrolyte. The sulfide solid electrolyte may be, for example, one or more of the following: 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 each positive numbers, and Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each positive numbers, and M is P, Si, Ge, B, Al, Ga, or 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) or Li 7-xPS 6-x I x (where 0 ≤ x ≤ 2). The sulfide solid electrolyte can be prepared as follows: by treating starting materials such as Li2S or P2S5, for example, by melt quenching or mechanical grinding. Additionally, after the treatment, heat treatment can be performed. The sulfide solid electrolyte can be amorphous, crystalline, or in a mixed state thereof.

[0142] Additionally, for example, among the sulfide solid electrolyte materials listed above, the sulfide solid electrolyte can include at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements. For example, the sulfide solid electrolyte can be a material including Li2S-P2S5. When a material including Li2S-P2S5 is used as the material for the sulfide solid electrolyte, the mixed molar ratio of Li2S and P2S5 can be in the range of, for example, Li2S: P2S5 = 50:50 to 90:10.

[0143] The sulfide solid electrolyte can include Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) or Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2), one or more argyrodite compounds. The sulfide solid electrolyte included as a solid electrolyte can be one or more argyrodite compounds including Li6PS5Cl, Li6PS5Br, or Li6PS5I. As used herein, argyrodite is a silver germanium sulfide mineral that can be called using the formula Ag8GeS6. As used herein, the term "argyrodite compound" means that the compound is isostructural with argyrodite. In the present disclosure, the term "isostructural" refers to the crystal structure of the compound. The crystal structures are the same, but the unit cell dimensions and / or chemical compositions can be different.

[0144] The sulfide solid electrolyte can be in the form of a powder or in the form of a molded product. The solid electrolyte in the form of a molded product can be in the form of a wafer, sheet, or film, but is not limited thereto and can have various forms depending on the intended use.

[0145] For example, the solid electrolyte 30 further includes a binder. The binder included in the solid electrolyte 30 may be styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto, and any binder used in the relevant technical field may be used. The binder of the solid electrolyte 30 may be of the same type or different from the binder of the positive electrode active material layer and the negative electrode active material layer.

[0146] All-solid-state battery

[0147] According to another embodiment, the all-solid-state battery may include an electrode-solid electrolyte subassembly 100, a positive electrode 10, a negative electrode 40, and a solid electrolyte 30 therebetween. The electrode of the electrode-solid electrolyte subassembly 100 may be the negative electrode 40 or the positive electrode 10. The electrode-solid electrolyte subassembly 100 may include the negative electrode 40 and the solid electrolyte 30. Alternatively, the electrode-solid electrolyte subassembly 100 may include the positive electrode 10 and the solid electrolyte 30. Since the content of the electrode-solid electrolyte subassembly 100 is the same as those described above, the following description will be omitted.

[0148] The all-solid-state battery may include a thin-film multilayer battery, a multilayer ceramic battery, a lithium-sulfur battery, or a lithium-air battery. For example, the all-solid-state battery may be an all-solid-state secondary battery.

[0149] Figure 4 It is a schematic diagram of an all-solid-state secondary battery 200 including a subassembly 100 for an electrode-solid electrolyte according to an embodiment.

[0150] Reference Figure 4 , the all-solid-state secondary battery 200 has a positive electrode 10 disposed below the solid electrolyte 30 of the electrode-solid electrolyte subassembly 100.

[0151] The positive electrode 10 may include a positive electrode current collector and a positive electrode active material layer.

[0152] The positive electrode current collector may use a metal substrate. Examples of the metal substrate may include aluminum (Al), indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode current collector may be in the form of a plate or a foil. The positive electrode current collector may be omitted.

[0153] As the positive electrode active material of the positive electrode active material layer, any material commonly used in the field of lithium batteries may be used without limitation. For example, the positive electrode active material may be one or more composite oxides of lithium and metals including cobalt, manganese, nickel, or a combination thereof, and specific examples thereof may include any compound represented by the following formula: Li a A 1-b B’ b D’2 (where 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b B’ b O 2-c D’ c (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); 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 ≤ 1.8, 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 ≤ 1.8, 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’2 (where 0.90 ≤ a ≤ 1.8, 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 ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Mn b B’ c O 2-α F’ α (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B’ c O 2-α F’2 (where 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni b Ec G d O2 (where 0.90 ≤ a ≤ 1.8, 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 ≤ 1.8, 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 ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O2; LiI’O2; LiNiVO4; Li (3-f) J2(PO4)3 (where 0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2); or LiFePO4. In the above formulas, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D' is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. For example, the positive electrode active material may include one or more of 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, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide. For example, the positive electrode active material may be LiCoO2, LiMn x O 2x (where x = 1, 2), LiNi 1-x Mn x O2 (where 0 < x < 1), LiNi 1-x-y Co x Mny O2 (where 0 ≤ x ≤ 0.5 and 0 ≤ y ≤ 0.5), LiFePO4, TiS2, FeS2, TiS3, or FeS3.

[0154] For example, the positive electrode active material includes a lithium salt of a transition metal oxide having a layered rock salt-type structure. "Layered rock salt-type structure" refers to the following structure: in which oxygen atom layers and metal atom layers are alternately and regularly arranged in the <111> direction of the cubic rock salt-type structure, whereby each atom layer forms a two-dimensional plane. "Cubic rock salt-type structure" refers to the sodium chloride (NaCl)-type structure (which is one of the crystal structures), and particularly refers to a structure in which the face-centered cubic (fcc) lattices formed by anions and cations respectively are shifted by only half of the ridges of each unit lattice. The lithium transition metal oxide having a layered rock salt-type structure may include those represented as LiNi x Co y Al z O2 (NCA) or LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1) of ternary lithium transition metal oxides. When the positive electrode active material includes a ternary transition metal oxide having a layered rock salt-type structure, the energy density and thermal stability of the all-solid-state secondary battery 200 can be improved.

[0155] A coating layer can be provided on the positive electrode active material. The coating layer can be any suitable material known as a coating layer for the positive electrode active material of the all-solid-state secondary battery 200. The coating layer can be, for example, Li2O-ZrO2.

[0156] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, the capacity density of the all-solid-state secondary battery 200 can be increased, and thus the elution of metal from the positive electrode active material during charging can be reduced. Therefore, the cycle characteristics of the all-solid-state secondary battery 200 can be improved.

[0157] For example, the positive electrode active material can have a particulate shape, such as a true spherical shape or an ellipsoidal shape. The particle diameter of the positive electrode active material is not particularly limited and can be within a suitable range useful in a typical all-solid-state secondary battery 200. The amount of the positive electrode active material in the positive electrode 10 is not particularly limited and can be within a suitable range useful in the positive electrode 10 of a typical all-solid-state secondary battery 200.

[0158] The positive electrode active material layer may further include an ionic liquid electrolyte. The ionic liquid electrolyte may be non-volatile. The ionic liquid has a melting point lower than room temperature and refers to a salt that consists solely of ions and is liquid at room temperature or a room temperature molten salt. The ionic liquid may be a compound including the following: a) at least one of the following cations: ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, or a mixture thereof, and b) at least one of the following anions: BF4 - , PF6 - , AsF 6- , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , SO4 2- , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , or (CF3SO2)2N - . The ionic liquid may be, for example, one or more of the following: N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The ionic liquid polymer may contain repeating units including the following: a) one or more of the following cations: ammonium-based cations, pyrrolidinium-based cations, pyridinium-based cations, pyrimidinium-based cations, imidazolium-based cations, piperidinium-based cations, pyrazolium-based cations, oxazolium-based cations, pyridazinium-based cations, phosphonium-based cations, sulfonium-based cations, triazolium-based cations, or a mixture thereof, and b) one or more of the following anions: BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 -, CF3CO2 - , (CF3SO2)2N - , (FSO2)2N - , Cl - , Br - , I - , SO4 2- , CF3SO3 - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , NO3 - , Al2Cl7 - , (CF3SO2)3C - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , SF5CF2SO3 - , SF5CHFCF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , or (O(CF3)2C2(CF3)2O)2PO - .

[0159] The ionic liquid electrolyte can be disposed in pores on the surface of the positive electrode active material layer in contact with the solid electrolyte. Based on 100 parts by weight of the positive electrode active material layer excluding the ionic liquid electrolyte, the amount of the ionic liquid electrolyte can be 0.1 to 20 parts by weight, 0.1 to 15 parts by weight, 0.1 to 10 parts by weight, or 0.1 to 5 parts by weight. By including the ionic liquid electrolyte, the ionic conductivity can be improved, thereby improving the charge and discharge characteristics of the battery.

[0160] The positive electrode active material layer may include a conductive material and a binder. For example, the conductive material may include carbon black, carbon fiber, graphite, or a combination thereof. For example, the carbon black may be acetylene black, Ketjen black, Super P carbon (superconductive carbon black), channel black, furnace black, lamp black, pyrolytic carbon black, or a combination thereof. The graphite may be natural graphite or artificial graphite. A combination of at least two of the foregoing may be used. In addition to the above conductive materials, the positive electrode active material layer may include conductive materials with different compositions. The additional conductive materials may be: conductive fibers, such as metal fibers; fluorocarbon powders; metal powders, such as aluminum powder or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; polyethylene derivatives; or a combination thereof. The conductive material may have a conductivity of at least 10 -2 Siemens per centimeter (S / cm). Based on 100 parts by weight of the positive electrode active material, the amount of the conductive material may be in the range of about 1 to about 10 parts by weight, for example, about 2 to about 7 parts by weight. When the amount of the conductive material is within this range, such as about 1 to about 10 parts by weight, the conductivity of the positive electrode may be sufficient.

[0161] The binder may improve the adhesion between the components of the positive electrode 10 and the adhesion to the positive electrode current collector. Examples of the binder may include polyacrylic acid (PAA), polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluorinated rubber, copolymers thereof, or a combination thereof. Based on 100 parts by weight of the positive electrode active material, the amount of the binder may be in the range of about 1 to about 10 parts by weight, for example, in the range of about 2 to about 7 parts by weight. When the amount of the binder is within this range, the adhesion of the positive electrode active material layer to the positive electrode current collector can be improved, and a decrease in the energy density of the positive electrode active material layer can be inhibited.

[0162] As the solvent, N-methylpyrrolidone, acetone, or water may be used. The amounts of the positive electrode active material, the conductive material, the binder, and the solvent are at common levels in a lithium battery.

[0163] A plasticizer may be added to the positive electrode active material composition to form pores within the positive electrode active material layer.

[0164] The positive electrode 10 may include a solid electrolyte. The solid electrolyte included in the positive electrode 10 may be the same (similar) or different from the solid electrolyte included in the solid electrolyte 30. For detailed content regarding the solid electrolyte, reference may be made to the content of the solid electrolyte 30. For example, the solid electrolyte included in the positive electrode 10 may be a sulfide solid electrolyte. As the sulfide solid electrolyte, the sulfide electrolyte used in the solid electrolyte 30 may be used.

[0165] Method for preparing an all-solid-state battery

[0166] According to another embodiment, a method for preparing an all-solid-state battery includes: providing a porous current collector 20 having a plurality of internal holes 22, a first side, and an opposite second side; disposing a composition containing an elastic polymer 23 on the first side of the porous current collector 20 to form a coated current collector; drying the coated current collector to form an elastic layer 21 containing the elastic polymer 23 and disposed on the first side of the porous current collector to prepare a porous current collector-elastic layer electrode, and the porous current collector-elastic layer electrode being a negative electrode 40 including the elastic polymer in at least one of the plurality of internal holes 22 of the porous current collector; providing a solid electrolyte 30; disposing the solid electrolyte 30 on the opposite second side of the porous current collector of the porous current collector-elastic layer electrode to prepare an electrode-solid electrolyte subassembly; and disposing a positive electrode 10 on the opposite side of the solid electrolyte 30 of the porous current collector-elastic layer electrode to prepare the all-solid-state battery.

[0167] First, the step of providing the porous current collector 20 having a first side and an opposite second side can be performed using laser drilling or punching. In this way, a porous current collector having a pattern of holes can be prepared, which includes a hole diameter S and a spacing I between two adjacent holes. The porous current collector can be a three-dimensional porous current collector. The ratio S / I of the hole diameter S to the spacing I between two adjacent holes can be from 0.1 to 0.9. The three-dimensional porous current collector can increase the capacity and energy density of the all-solid-state battery. If the ratio S / I of the hole diameter to the spacing between the holes is within the above range, excellent contact between the porous current collector and the electrode active material can be maintained (during charging), thereby providing an all-solid-state battery having a low interfacial resistance and excellent charge and discharge characteristics.

[0168] Separately, a composition containing an elastic polymer can be prepared. The composition containing an elastic polymer can include the elastic polymer and a solvent. The elastic polymer can include a copolymer having at least one hard structural unit and at least one soft structural unit, and the weight ratio of the hard structural unit to the soft structural unit can be from 0.1 to 1. The solvent can be an organic solvent and can include, for example, dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), or a mixture thereof. Based on the total weight of the composition containing the elastic polymer, the composition containing the elastic polymer can include about 1 to 5% by weight of the elastic polymer.

[0169] Next, an elastic layer 21 including an elastic polymer 23 can be formed on the first side of the porous current collector 20 as follows: A composition containing an elastic polymer is provided on the porous current collector 20 to provide a coated current collector, and the coated current collector is dried to form an elastic layer provided on the first side of the porous current collector to prepare a porous current collector-elastic layer electrode including the elastic polymer 23. The elastic polymer 23 can be disposed in at least one of a plurality of internal pores of the porous current collector.

[0170] Any known application method can be used as the method for applying the composition containing an elastic polymer to the porous current collector 20, but the application and curing can be carried out, for example, by a solution process such as spin coating. The composition containing an elastic polymer can include, for example, a curing agent. Spin coating can be carried out at a speed of about 500 to 1500 revolutions per minute (rpm) for about 10 to about 60 seconds. Drying can be carried out under reduced pressure (e.g., below atmospheric pressure) at a temperature of about 60°C to 100°C for 30 minutes to 2 hours.

[0171] Independently, a solid electrolyte 30 can be prepared. As the solid electrolyte, a solid electrolyte molded body can be prepared. The solid electrolyte molded body can be prepared, for example, as follows: Heat-treating a solid electrolyte material (e.g., a precursor including an oxide solid electrolyte material).

[0172] An oxide solid electrolyte can be prepared as follows: precursor materials are mixed in stoichiometric amounts to form a mixture, and the mixture is heat-treated. The mixing can include, for example, milling (such as ball milling) or grinding. The mixture of precursor materials can be subjected to a primary heat treatment in an oxidizing atmosphere to prepare a primary heat-treated product. The primary heat treatment can be carried out at a temperature below 1000 °C for 1 hour to about 36 hours. The primary heat-treated product can be milled. The milling of the primary heat-treated product can be carried out by a dry or wet process. Wet milling can be carried out, for example, by mixing a solvent (such as methanol) with the primary heat-treated product and then milling the product for 0.5 hour to 10 hours using a ball mill or the like. Dry milling can be carried out by milling without a solvent using a ball mill or the like. The average particle diameter of the milled primary heat-treated product can be 0.1 μm to 10 μm, or 0.1 μm to 5 μm. The milled primary heat-treated product can be dried. The milled primary heat-treated product can be mixed with a binder solution and formed into a wafer, or simply pressed at a pressure of 1 to 10 tons to form a wafer. The molded body can be subjected to a secondary heat treatment at a temperature below or equal to 1000 °C for 1 hour to 36 hours. Through the secondary heat treatment, a sintered solid electrolyte molded body can be obtained. The secondary heat treatment can be carried out, for example, at 550 °C to 1000 °C. The secondary heat treatment time can be 1 hour to 36 hours. In order to obtain a sintered product, the secondary heat treatment temperature can be higher than the primary heat treatment temperature. For example, the secondary heat treatment temperature can be 10 °C or more, 20 °C or more, 30 °C or more, or 50 °C or more higher than the primary heat treatment temperature. The molded product can be subjected to the secondary heat treatment in one or more of an oxidizing atmosphere or a reducing atmosphere. The secondary heat treatment can be carried out in a) an oxidizing atmosphere, b) a reducing atmosphere, or c) an oxidizing atmosphere and a reducing atmosphere. Alternatively, the oxide solid electrolyte can be prepared using a tape casting method. For example, an oxide solid electrolyte slurry can be prepared by mixing an oxide solid electrolyte powder with a binder and a solvent. The oxide solid electrolyte slurry can be ball milled for 12 hours to 24 hours and aged for 1 hour to 4 hours. The aged oxide solid electrolyte slurry can be poured onto a doctor blade set at a predetermined height, and a PET substrate film can be moved at a speed of 1.0 m / min to 3.0 m / min for tape casting to prepare a green sheet having a thickness of several tens of micrometers. Through stacking, pressing, and cutting, the green sheet can be sintered at a temperature of 1000 °C to 1350 °C to provide a sintered body. By placing the sintered body in a mold and applying pressure thereto, a solid electrolyte molded body having a thickness of several hundreds of micrometers can be prepared.

[0173] The solid electrolyte 30 may have been surface-treated. Examples of the surface treatment may include chemical treatment, electropolishing, wet polishing, argon plasma etching, oxygen plasma cleaning, annealing, or exposure to high vacuum. For example, acid treatment may be used as the chemical treatment. For example, the acid treatment may be performed at a concentration of 0.1 molar per liter (M) to 10 M for 30 minutes to 1 hour. For example, the acid treatment may be performed with hydrochloric acid at a concentration of 0.1 M to 1 M for 30 minutes to 1 hour. After the acid treatment, the surface-treated solid electrolyte 30 may be obtained by washing with an alkaline or neutral compound (such as ethanol) and then drying. In the surface-treated solid electrolyte 30, the electrode active material may penetrate into its surface (during charging), and the contact area with the solid electrolyte 30 may increase, thereby reducing the interfacial resistance.

[0174] After preparing the porous current collector - elastic layer negative electrode 40, the intermediate layer 25 may be disposed on the opposite second side (the solid electrolyte side) of the porous current collector 20. The intermediate layer 25 may include: a carbon-containing material; a mixture of one or more of a metal or a metalloid and a carbon-containing material; a composite of one or more of a metal or a metalloid and a carbon-containing material; or a combination thereof. Since the specific details of the carbon-containing material, the metal and the metalloid, their mixtures and composites are the same as those described above, the description will be omitted hereinafter.

[0175] Next, the porous current collector - elastic layer negative electrode 40 may be combined with the solid electrolyte 30 to prepare the electrode - solid electrolyte subassembly 100.

[0176] The placement and combination of the intermediate layer may be performed by pressing or compressing.

[0177] For example, the pressure applied during pressing or compressing may be 150 MPa or greater. For example, the pressure applied during pressing may be 250 MPa or greater. For example, the pressure applied during pressing or compressing may be 10,000 MPa or less, such as 150 MPa to 10,000 MPa, 300 MPa to 5,000 MPa, or 500 MPa to 2,000 MPa.

[0178] The time for applying the pressure may be less than or equal to 10 minutes. For example, the time for applying the pressure may be 5 milliseconds (ms) to 10 minutes (min). For example, the time for applying the pressure may be 2 min to 7 min.

[0179] For example, the pressing may be performed at room temperature (25 °C). For example, the pressing may be performed at 15 °C to 25 °C. However, the pressing temperature is not limited thereto, and may be a high temperature of 25 °C to 90 °C, or 100 °C or greater, such as 100 °C to 500 °C.

[0180] For example, the pressing may be, but is not limited to, roll pressing, uniaxial pressing, flat pressing, warm isostatic pressing (WIP), or cold isostatic pressing (CIP), and any pressing method used in the relevant technical field may be used.

[0181] Next, the positive electrode 10 may be placed on the opposite side of the solid electrolyte 30 in contact with the porous current collector - elastic layer negative electrode 40.

[0182] A slurry may be prepared by adding a positive electrode active material, a binder, etc. (which are materials for forming the positive electrode active material layer) to a non - polar solvent. The prepared slurry may be applied to the positive electrode current collector and dried. The obtained laminate may be pressed to prepare the positive electrode 10. For example, the pressing may be, but is not limited to, roll pressing, flat pressing, pressing using hydrostatic pressure, etc., and any pressing method used in the relevant technical field may be used. The pressing process may be omitted. The positive electrode 10 may be prepared by compressing and molding a mixture of materials for forming the positive electrode active material layer into a disc form, or stretching (molding) it into a sheet form. When the positive electrode 10 is prepared in this way, the positive electrode current collector may be omitted. Alternatively, the positive electrode 10 may be used by impregnating it with an electrolyte solution.

[0183] Next, before applying the composition containing the elastic polymer to the first surface (opposite to the solid electrolyte) of the porous current collector, a metal layer 24 may be provided between the first side of the porous current collector and the elastic layer by providing a metal layer 24 on the first surface (opposite to the surface of the solid electrolyte) of the porous current collector. Since the type and formation method of the metal layer 24 are the same as those described above, the description thereof will be omitted below.

[0184] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only examples of the present invention, and the present invention is not limited to the following examples.

[0185] Examples

[0186] Preparation of All - Solid - State Secondary Battery

[0187] Example 1: All - Solid - State Secondary Battery

[0188] Preparation of Negative Electrode - Solid Electrolyte Sub - Assembly

[0189] A solution containing 5.0 wt% of an elastic polymer was prepared by dissolving a styrene-ethylene-butene-styrene copolymer (SPIN ON GLASS COATER, ANSWORLDCO., LTD.) in dimethylformamide. The styrene-ethylene-butene-styrene copolymer is represented by Formula A and has a styrene structural unit as a hard structural unit and ethylene and butene structural units as soft structural units, and the (y / x+z) weight ratio is 0.88.

[0190] Formula A

[0191]

[0192] Individually, copper foam (Cu foam) (porosity: 77%, thickness: 20 μm) was subjected to a laser drilling process to prepare a three-dimensional porous negative electrode current collector having a uniform pattern of pore size and spacing and having a first side and an opposite second side.

[0193] A 20-μm-thick elastic polymer layer was formed on the first side (opposite to the solid electrolyte side) of the three-dimensional porous current collector by using a spin coater at a speed of 1500 rpm to coat the solution containing the elastic polymer on top of and inside the three-dimensional porous negative electrode current collector for 60 seconds in a direction opposite to the solid electrolyte side, and drying it under reduced pressure at 80 °C for 1 hour, and a porous current collector-elastic layer negative electrode was prepared, wherein about 85 vol% of a plurality of internal pores based on the total volume of the plurality of internal pores were filled with the elastic polymer in a concentration gradient decreasing in the direction from the first side to the opposite second side (solid electrolyte side) of the three-dimensional porous negative electrode current collector.

[0194] Individually, a Li 6.5 La3Zr 1.5 Ta 0.5 O 12 (LLZTO, Toshima Co.) solid electrolyte wafer was prepared. The LLZTO solid electrolyte was treated with 1 M hydrochloric acid for 30 minutes, then washed with ethanol and dried in a drying chamber to provide a surface-treated Li 6.5 La3Zr 1.5 Ta 0.5 O 12 solid electrolyte layer of the solid electrolyte wafer.

[0195] Individually, a mixer (AR-100, Thinky Corporation) was used to mix carbon black powder (99.7% purity, D50: 38 nm, Asahi carbon) and silver (Ag) nanoparticles (D50: 60 nm) at a weight ratio of 1:3 in N-methylpyrrolidone (Sigma-Aldrich) with 7 wt% polyvinylidene fluoride binder (Solvay) based on the weight of N-methylpyrrolidone at a speed of 1000 rpm for 30 minutes. The mixture was coated on a 10 μm thick stainless steel (SUS) foil using a screen printing machine and dried in an air atmosphere at 80 °C for 20 minutes to form an Ag-C layer. The Ag-C layer was further dried in a vacuum atmosphere at 100 °C for 12 hours.

[0196] Cold isostatic pressing was carried out at a temperature of 25 °C and a pressure of 250 MPa to laminate the dried Ag-C layer as an intermediate layer on the surface-treated Li 6.5 La3Zr 1.5 Ta 0.5 O 12 solid electrolyte wafer. After peeling off the SUS foil from the stainless steel (SUS) foil coated with the Ag-C layer, the opposite second side of the three-dimensional porous negative electrode current collector was subjected to cold isostatic pressing on the Ag-C layer at a temperature of 25 °C and a pressure of 250 MPa, thereby preparing a negative electrode-solid electrolyte subassembly.

[0197] Preparation of the positive electrode

[0198] LiNi 0.33 Co 0.33 Mn 0.33 O2 (NCM, loading: 3.2 grams per cubic centimeter (g / cc), Samsung SDI) was prepared as the positive electrode active material. Additionally, polytetrafluoroethylene (DuPont, Teflon®) was prepared as the binder. Additionally, carbon nanofibers (CNF) were prepared as the conductive material. Then, these materials were mixed at a weight ratio of 96:2:2 of positive electrode active material: conductive material: binder. The mixture was stretched into a sheet form to prepare a positive electrode active material sheet with a thickness of approximately 50 μm. Then, the positive electrode was prepared by pressing the positive electrode active material sheet onto a 9 μm thick aluminum foil (Nippon Foil Mfg. Co., Ltd) positive electrode current collector.

[0199] The prepared positive electrode active material sheet was immersed in an electrolyte solution in which 2.0 M lithium bis(fluorosulfonyl)imide [(LiFSI, 99.9% purity, moisture content < 10 parts per million (ppm)] as a lithium salt was dissolved in N-methyl-N-propyl-pyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI, 99.9% purity, Kanto Chemical Co., Inc.) as an ionic liquid in a drying chamber, and left for 2 hours under reduced pressure. Residual liquid on the surface of the positive electrode was removed using Kimwipes.

[0200] Preparation of All-Solid-State Secondary Battery

[0201] In a single-layer pouch cell, the positive electrode impregnated with the electrolyte solution was placed on a negative electrode - solid electrolyte subassembly (such that the solid electrolyte was disposed between the positive electrode and the negative electrode), and sealed under reduced pressure, thereby preparing an all-solid-state secondary battery. The positive electrode and the negative electrode were insulated with an insulator. Parts of the positive electrode current collector and the negative electrode current collector were respectively allowed to protrude outside the sealed battery and used as the positive electrode layer terminal and the negative electrode layer terminal.

[0202] Example 2: All-Solid-State Secondary Battery

[0203] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that an 80-μm-thick elastic polymer layer was formed on the first side (opposite to the solid electrolyte side) of the three-dimensional porous current collector as follows: A solution containing 25.0 wt% of an elastic polymer was spin-coated at a speed of 1000 rpm in a direction opposite to the solid electrolyte side on top of and inside the three-dimensional porous negative electrode current collector for 30 seconds, and dried at 80 °C under reduced pressure for 1 hour, and a porous current collector - elastic layer negative electrode was prepared, in which about 55 vol% of a plurality of internal pores were filled with the elastic polymer based on the total volume of the plurality of internal pores in a concentration gradient decreasing in the direction from the first side to the opposite second side (solid electrolyte side) of the three-dimensional porous negative electrode current collector.

[0204] Example 3: All-Solid-State Secondary Battery

[0205] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except for the following: A solution containing 7.5 wt% of an elastic polymer was prepared by dissolving a copolymer of styrene - ethylene - butene - styrene (SPIN ON GLASS COATER, ANSWORLD CO., LTD.) in dimethylformamide. The copolymer of styrene - ethylene - butene - styrene was represented by Formula A and had a styrene structural unit as a hard structural unit and ethylene structural unit and butene structural unit as soft structural units, and the (y / x + z) weight ratio was 0.88.

[0206] Forming a 30-μm-thick elastic polymer layer on the first side (opposite to the solid electrolyte side) of the three-dimensional porous current collector as follows: Using a spin coater at a speed of 1500 rpm in the direction opposite to the solid electrolyte side, coating a solution containing the elastic polymer on top of and inside the three-dimensional porous negative current collector for 60 seconds, and drying it under reduced pressure at 80 °C for 1 hour, and preparing a porous current collector-elastic layer negative electrode, wherein based on the total volume of the plurality of internal pores, approximately 85% by volume of the plurality of internal pores are filled with the elastic polymer with a concentration gradient decreasing in the direction from the first side to the opposite second side (solid electrolyte side) of the three-dimensional porous negative current collector.

[0207] Example 4: All-solid-state secondary battery

[0208] An all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that a 50-μm-thick elastic polymer layer was formed on the first side (opposite to the solid electrolyte side) of the three-dimensional porous current collector as follows: Using a spin coater at a speed of 1000 rpm in the direction opposite to the solid electrolyte side, coating a solution containing 15.0 wt% of the elastic polymer on top of and inside the three-dimensional porous negative current collector for 30 seconds, and drying it under reduced pressure at 80 °C for 1 hour, and preparing a porous current collector-elastic layer negative electrode, wherein based on the total volume of the plurality of internal pores, approximately 55% by volume of the plurality of internal pores are filled with the elastic polymer with a concentration gradient decreasing in the direction from the first side to the opposite second side (solid electrolyte side) of the three-dimensional porous negative current collector.

[0209] Example 5: All-solid-state secondary battery

[0210] An all-solid-state secondary battery was fabricated in the same manner as in Example 1, except for the following: A solution containing 5.0 wt% of the elastic polymer was prepared by dissolving a copolymer of styrene-ethylene-butene-styrene (SPIN ON GLASS COATER, ANSWORLD CO., LTD.) in dimethylformamide. The copolymer of styrene-ethylene-butene-styrene is represented by Formula A and has a styrene structural unit as a hard structural unit and ethylene and butene structural units as soft structural units, and the (y / x + z) weight ratio is 0.80.

[0211] Example 6: All-solid-state secondary battery

[0212] A all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that: A solution containing 5.0 wt% of an elastic polymer was prepared by dissolving a copolymer of styrene-ethylene-butene-styrene (SPIN ON GLASS COATER, ANSWORLD CO., LTD.) in dimethylformamide. The copolymer of styrene-ethylene-butene-styrene is represented by Formula A and has a styrene structural unit as a hard structural unit and ethylene and butene structural units as soft structural units, and the (y / x+z) weight ratio is 0.78.

[0213] Example 7: All-solid-state secondary battery

[0214] A all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that: A solution containing 5.0 wt% of an elastic polymer was prepared by dissolving a copolymer of styrene-ethylene-butene-styrene (SPIN ON GLASS COATER, ANSWORLD CO., LTD.) in dimethylformamide. The copolymer of styrene-ethylene-butene-styrene is represented by Formula A and has a styrene structural unit as a hard structural unit and ethylene and butene structural units as soft structural units, and the (y / x+z) weight ratio is 0.70.

[0215] Comparative Example 1: All-solid-state secondary battery

[0216] A all-solid-state secondary battery was prepared in the same manner as in Example 1, except that: A porous current collector-elastic layer negative electrode was prepared in which the internal pores of the three-dimensional porous current collector were not filled with an elastic polymer, and no elastic polymer layer was formed on the first side (opposite to the solid electrolyte side) of the three-dimensional porous current collector.

[0217] Comparative Example 2: All-solid-state secondary battery

[0218] A all-solid-state secondary battery was prepared in the same manner as in Example 1, except that: A porous current collector negative electrode was prepared by coating a solution containing an elastic polymer on a three-dimensional porous negative current collector at a speed of 500 rpm for 10 seconds using a spin coater in the direction of the solid electrolyte side and drying it under reduced pressure at 80 °C for 1 hour. In the direction from the opposite second side (solid electrolyte side) to the first side (opposite to the solid electrolyte side) of the three-dimensional porous negative current collector, about 85% by volume of the total volume of the plurality of internal pores were filled with the elastic polymer at a decreasing concentration gradient.

[0219] Comparative Example 3: All-solid-state secondary battery

[0220] A all-solid-state secondary battery was prepared in the same manner as in Example 1, except that: a solution containing 10.0 wt% of an elastic polymer was prepared by dissolving a copolymer of styrene-ethylene-butene-styrene (SPIN ON GLASS COATER, ANSWORLD CO., LTD.) in dimethylformamide. The copolymer of styrene-ethylene-butene-styrene is represented by Formula A and has a styrene structural unit as a hard structural unit and ethylene and butene structural units as soft structural units, and the (y / x+z) weight ratio is 0.88.

[0221] A 50-μm-thick elastic polymer layer was formed by coating the solution containing 10.0 wt% of the elastic polymer on a copper foil using a doctor blade and drying it under reduced pressure at 80 °C for 1 hour.

[0222] A porous current collector-elastic layer negative electrode was prepared by bonding the elastic polymer layer to the first side (opposite to the solid electrolyte side) of a three-dimensional porous current collector.

[0223] Evaluation Example 1: SEM analysis

[0224] Each of the all-solid-state secondary batteries prepared in Examples 1 and 2 was disassembled, and a three-dimensional porous negative electrode current collector of the negative electrode-solid electrolyte subassembly was subjected to scanning electron microscope (SEM) analysis. The results are shown in Figure 5A and 5B respectively.

[0225] SEM analysis was performed using an S-4700FE-SEM (Hitachi) analysis device in the secondary electron (SE) mode, with an energy of 2.00 kV and a magnification of 20,000×.

[0226] Refer to Figure 5A and 5B From the first side to the opposite second side of the three-dimensional porous negative electrode current collector included in the all-solid-state secondary batteries prepared in Examples 1 and 2, the elastic polymer was filled to depths of 12.8 μm and 8.3 μm, respectively, of a total depth of 15 μm of the internal pores, and the pores were filled to 85.3 vol% and 55.3 vol%, respectively.

[0227] Evaluation Example 2: Interface resistance experiment

[0228] The impedance of the all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 was measured using the two-probe method, as analyzed using an impedance analyzer (Solartron 1400A / 1455A impedance analyzer) at 25 °C in an air atmosphere. Impedance measurements were performed in the frequency range of 0.1 Hertz (Hz) to 1 Megahertz (MHz) and at an amplitude voltage of 10 millivolts (mV). The Nyquist plots based on the impedance measurement results are provided in Figure 6A and 6B . Figure 6A show the impedance results for the all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2, and Figure 6B is an enlarged view of the impedance results for the all-solid-state secondary batteries prepared in Figure 6A Example 1, Example 2, and Comparative Example 1.

[0229] As a result of fitting the Nyquist plots of Figure 6A and 6B to an equivalent circuit, the interfacial resistances of the all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were approximately 79 ohm-square centimeters (Ωcm 2 ), 87 Ωcm 2 , 75 Ωcm 2 , and 1167 Ωcm 2 , respectively.

[0230] Therefore, the interfacial resistances of the all-solid-state secondary batteries prepared in Examples 1 and 2 are less than that of the all-solid-state secondary battery manufactured in Comparative Example 2.

[0231] Evaluation Example 3: Charge and Discharge Test (I)

[0232] The all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were subjected to charge and discharge tests in a constant temperature bath at 25 °C.

[0233] In the first cycle, the battery was charged at a constant current of 0.3 milliamperes per square centimeter (mA / cm 2 ) until the battery voltage reached 4.4 volts (V). Subsequently, it was discharged at a constant current of 0.3 mA / cm 2 until the battery voltage reached 2.85 V.

[0234] In the second cycle, the battery was charged at a constant current of 0.5 mA / cm 2 until the battery voltage reached 4.4 V. Subsequently, it was discharged at a constant current of 0.5 mA / cm 2 until the battery voltage reached 2.85 V.

[0235] In all charge / discharge cycles, a 1-minute stop time is given after one charge / discharge cycle. The charge and discharge test results of the all-solid-state secondary battery prepared in Example 1 are shown in Figure 7A and the charge and discharge test results of the all-solid-state secondary batteries prepared in Comparative Examples 1 and 2 are shown in Figure 7B . In addition, the results of the charge / discharge efficiency (%) determined by calculating the ratio of the charge capacity to the discharge capacity in each cycle of the all-solid-state secondary batteries prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Table 1.

[0236] Table 1

[0237]

[0238] Referring to Table 1, the charge / discharge efficiency of each of the all-solid-state secondary batteries prepared in Example 1 and Example 2 is greater than that of each of the all-solid-state secondary batteries prepared in Comparative Examples 1 and 2.

[0239] Referring to Figure 7A , the all-solid-state secondary battery prepared in Example 1 shows a capacity per unit area of about 3.0 mA / cm 2 to about 3.2 mA / cm 2 .

[0240] Referring to Figure 7B , the all-solid-state secondary battery prepared in Comparative Example 1 shows a capacity per unit area of about 2.3 mA / cm 2 to about 2.8 mA / cm 2 during 2 cycles, and the all-solid-state secondary battery prepared in Comparative Example 2 could not even operate for 1 cycle.

[0241] Therefore, compared with the all-solid-state secondary batteries prepared in Comparative Examples 1 and 2, the all-solid-state secondary battery prepared in Example 1 shows stable operation at a high capacity per unit area.

[0242] Evaluation Example 4: Charge and Discharge Test (II)

[0243] Charge and discharge tests were performed on the all-solid-state secondary batteries prepared in Example 1 and Comparative Example 1 in a constant temperature bath at 25°C.

[0244] In the first cycle, the battery was charged at a constant current of 0.3 mA / cm 2 until the battery voltage reached 4.4 V. Subsequently, it was discharged at a constant current of 0.3 mA / cm 2 until the battery voltage reached 2.85 V.

[0245] In the second and third cycles, the battery was charged at a constant current of 0.5 mA / cm 2 until the battery voltage reached 4.4 V. Subsequently, it was discharged at a constant current of 0.5 mA / cm 2 until the battery voltage reached 2.85 V.

[0246] In the fourth and fifth cycles, the battery was charged at a constant current of 1.0 mA / cm 2 until the battery voltage reached 4.4 V. Subsequently, it was discharged at a constant current of 1.0 mA / cm 2 until the battery voltage reached 2.85 V.

[0247] In the sixth to fortieth cycles, the battery was charged at a constant current of 1.6 mA / cm 2 until the battery voltage reached 4.4 V. Subsequently, it was discharged at a constant current of 1.6 mA / cm 2 until the battery voltage reached 2.85 V.

[0248] In all charge / discharge cycles, a 1-minute stop time was given after one charge / discharge cycle. The results of the charge and discharge tests are shown in Figure 8 .

[0249] Refer to Figure 8 . The all-solid-state secondary battery prepared in Example 1 operated with a stable capacity per unit area until the fortieth cycle, and the capacity retention rate calculated as the ratio (%) of the discharge capacity in the first cycle to the discharge capacity in the fortieth cycle was approximately 91.1%.

[0250] In contrast, the all-solid-state secondary battery prepared in Comparative Example 1 continuously decreased in capacity per unit area until the tenth cycle and could not operate thereafter.

[0251] Therefore, compared with the all-solid-state secondary battery prepared in Comparative Example 1, the all-solid-state secondary battery prepared in Example 1 has improved life characteristics.

[0252] Evaluation Example 5: Optical Microscope

[0253] The all-solid-state secondary battery prepared in Example 1 was charged and discharged once at 0.2 C, where C refers to the C-rate, that is, the current at which a charged battery is discharged in one hour. For example, the C-rate of a battery with a discharge capacity of 1.6 ampere-hours would be 1.6 amperes. Subsequently, the all-solid-state secondary battery was disassembled, and the surface of the three-dimensional porous negative electrode current collector of the copper foam facing the laser drilling was observed using an optical microscope. The results of the optical microscope analysis are shown in Figure 9A and9B and in 9C. Figure 9A An optical microscope photograph magnified two times of the surface of the three-dimensional porous negative electrode current collector of laser-drilled copper foam in the all-solid-state secondary battery prepared in Example 1 before charging. Figure 9B and 9C After charging and discharging the all-solid-state secondary battery once at 0.2 C and disassembling it, Figure 9A An optical microscope photograph magnified two times of the surface of the three-dimensional porous negative electrode current collector of laser-drilled copper foam in the all-solid-state secondary battery shown in

[0254] Referring to the microscope photograph, it can be confirmed that lithium (gray particles) is deposited in the formed pores (circular regions indicated by dotted lines during charging) of the three-dimensional porous negative electrode current collector of the all-solid-state secondary battery prepared in Example 1, and lithium desorbs from the same pores during discharging.

[0255] It is thus confirmed that during charging and discharging, lithium is deposited / desorbed in the pores of the three-dimensional porous current collector of the all-solid-state secondary battery prepared in Example 1.

[0256] The subassembly for an electrode-solid electrolyte according to an aspect includes: an electrode including a porous current collector having a first side and an opposite second side; an elastic layer including an elastic polymer and disposed on the first side of the porous current collector; and a solid electrolyte disposed on the opposite second side of the porous current collector, wherein the porous current collector includes a plurality of internal pores, and the elastic polymer is disposed in at least one of the plurality of internal pores of the porous current collector. (During charging) The electrode-solid electrolyte subassembly can maintain excellent contact between the porous current collector and the electrode active material, thereby providing an all-solid-state battery having low interfacial resistance and excellent charging and discharging characteristics.

[0257] It should be understood that the embodiments described herein should be considered only in the descriptive sense and not for purposes of limitation. The description of features or aspects within each embodiment should typically be considered applicable to other similar features or aspects in 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 various changes in form and detail may be made therein without departing from the spirit and scope defined by the appended claims.

Claims

1. Subassemblies for electrode-solid electrolyte, including: an electrode comprising a porous current collector having a first side and an opposing second side; an elastic layer comprising an elastic polymer and disposed on the first side of the porous current collector; and a solid electrolyte disposed on the opposite second side of the porous current collector; The porous current collector comprises a plurality of internal pores, and the elastic polymer is disposed in at least one internal pore of the plurality of internal pores of the porous current collector.

2. The electrode-solid electrolyte subassembly of claim 1 , wherein the porous current collector has a porosity of 10% to 99% by volume based on the total volume of the porous current collector and an average pore diameter of 0.1 to 100 microns.

3. The electrode-solid electrolyte subassembly of claim 1 , wherein the porous current collector is a three-dimensional porous current collector comprising a pore diameter S and an interval I between two adjacent pores, and a ratio S / I of the pore diameter to the interval is 0.1 to 0.

9.

4. The subassembly for an electrode-solid electrolyte according to claim 3, wherein a horizontal cross-sectional shape of at least one of the pores of the three-dimensional porous current collector is circular, elliptical, triangular, square, rectangular or hexagonal.

5. The subassembly for an electrode-solid electrolyte according to claim 1, wherein the porous current collector comprises copper, nickel, silver, aluminum, stainless steel, titanium, iron, chromium, cobalt or a combination thereof. 6 . The subassembly for an electrode-solid electrolyte according to claim 1 , wherein the elastic polymer has a Young's modulus of 1 MPa to 50 MPa when measured according to DMA (Dynamic Mechanical Analysis).

7. The electrode-solid electrolyte subassembly of claim 1, wherein the elastic polymer comprises a copolymer having at least one hard structural unit and at least one soft structural unit, and The weight ratio of the hard structural unit to the soft structural unit is 0.1 to 1.

8. The electrode-solid electrolyte subassembly of claim 7, wherein the hard structural unit comprises a styrene structural unit, a carbamate structural unit, an ether structural unit or a combination thereof, and The soft structural unit includes an ethylene structural unit, a propylene structural unit, a butylene structural unit, an isobutylene structural unit, a butadiene structural unit, an isoprene structural unit or a combination thereof.

9. The electrode-solid electrolyte subassembly of claim 1, wherein the elastic polymer comprises styrene-butadiene rubber, styrene-ethylene-butylene-styrene rubber, styrene-ethylene-propylene-styrene rubber, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, styrene-isobutylene-styrene rubber or a combination thereof.

10. The electrode-solid electrolyte subassembly of claim 1, wherein the elastic polymer is disposed in the plurality of internal pores at a content of 10 volume % to 90 volume % based on the total volume of the plurality of internal pores of the porous current collector.

11. A subassembly for an electrode-solid electrolyte as described in claim 1, wherein the elastic polymer is arranged in the multiple internal pores with a concentration gradient decreasing in a direction from the first side of the porous current collector to the opposite second side, and based on the total volume of the multiple internal pores of the porous current collector, the elastic polymer is arranged in the multiple internal pores at 55 volume % to 85 volume %.

12. The electrode-solid electrolyte subassembly of claim 1, wherein the elastic polymer further comprises a -2 The electrical conductivity of an electronically conducting material is measured in Siemens / cm.

13. The subassembly for an electrode-solid electrolyte according to claim 12, wherein the electron conductive material comprises carbon nanotubes, carbon nanofibers, carbon nanowires, carbon nanoparticles or a combination thereof.

14. The subassembly for an electrode-solid electrolyte of claim 1, further comprising a metal layer disposed between the first side of the porous current collector and the elastic layer.

15. The electrode-solid electrolyte subassembly of claim 1, further comprising an intermediate layer disposed between the opposite second side of the porous current collector and the solid electrolyte, The intermediate layer includes a carbon-containing material, a mixture of at least one metal or metalloid and a carbon-containing material, a composite of one or more metals or metalloids and a carbon-containing material, or a combination thereof.

16. The subassembly for an electrode-solid electrolyte according to claim 15, wherein the carbonaceous material comprises amorphous carbon, and The metals and metalloids include indium, silicon, gallium, tin, aluminum, titanium, zirconium, niobium, germanium, antimony, bismuth, gold, platinum, palladium, magnesium, silver, zinc, nickel, iron, cobalt, chromium, cesium, sodium, potassium, calcium, yttrium, tantalum, hafnium, barium, vanadium, strontium, lanthanum, or combinations thereof.

17. The subassembly for an electrode-solid electrolyte according to claim 1, wherein the elastic layer has a thickness of 10 to 100 micrometers.

18. The subassembly for an electrode-solid electrolyte according to claim 1, wherein a combined thickness of the porous current collector and the elastic layer is 20 micrometers to 100 micrometers.

19. All-solid-state batteries, including: The subassembly for an electrode-solid electrolyte according to any one of claims 1 to 18, wherein the electrode is a negative electrode; and positive electrode; The solid electrolyte of the electrode-solid electrolyte subassembly is interposed between the negative electrode and the positive electrode.

20. A method for preparing the all-solid-state battery according to claim 19, the method comprising: providing a porous current collector having a first side and an opposite second side, wherein the porous current collector comprises a plurality of internal pores; disposing a composition comprising an elastomeric polymer on the first side of the porous current collector to form a coated current collector; Drying the coated current collector to form an elastic layer comprising an elastic polymer and disposed on the first side of the porous current collector to prepare a porous current collector-elastic layer electrode comprising the elastic polymer, wherein the elastic polymer is disposed in at least one internal pore of the plurality of internal pores, and the porous current collector-elastic layer electrode is a negative electrode; providing a solid electrolyte; disposing the solid electrolyte on the opposite second side of the porous current collector of the porous current collector-elastic layer electrode to prepare an electrode-solid electrolyte subassembly; and A positive electrode is disposed on the opposite side of the solid electrolyte of the subassembly for electrode-solid electrolyte to prepare the all-solid-state battery.

Images