Solid electrolyte membrane, method of manufacturing same, and all-solid-state secondary battery including same

Abstract

The present invention relates to a solid electrolyte membrane, a method of manufacturing the same, and an all-solid-state secondary battery including the same. A solid electrolyte membrane includes a solid electrolyte, a high molecular weight polymeric binder having a weight average molecular weight of about greater than 75,000 g / mol (g / mol) but less than or equal to 1,000,000 g / mol, and a low molecular weight non-polar liquid rubber (non-polar elastomer), where the low molecular weight non-polar liquid rubber has a weight average molecular weight of about 2,000 g / mol to about 75,000 g / mol, and a viscosity of about 1 centipoise (cps) to about 100,000 cps. The all-solid-state secondary battery includes the solid electrolyte membrane.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefits arising from Korean Patent Application No. 10-2023-0159285 filed on November 16, 2023 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present disclosure relates to a solid electrolyte membrane, a method of manufacturing the same, and an all-solid-state secondary battery including the same. Background Art

[0004] The solid electrolyte membrane can be obtained by applying a composition for forming a solid electrolyte membrane including a solid electrolyte, a solvent, and a binder to a substrate, and then drying the resulting substrate. In the manufacture of the solid electrolyte membrane, when a process such as rolling for large-scale mass production is applied, the solid electrolyte membrane undergoes a pressing and drying process to reduce the pores of the membrane and increase the density of the membrane. During these processes, the brittleness of the solid electrolyte can increase rapidly, resulting in microcracks or ruptures (fractures). This directly affects the battery cell assembly process that constitutes the subsequent process, and therefore, there is a continuous need to improve the physical properties of the solid electrolyte membrane after the pressing process. Summary of the invention

[0005] Provided are a solid electrolyte membrane having improved flexibility and a method of manufacturing the same.

[0006] Provided is an all-solid-state secondary battery having improved stability by including the solid electrolyte membrane described above.

[0007] 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 presented embodiments of the disclosure.

[0008] According to one aspect of the present disclosure, a solid electrolyte membrane includes a solid electrolyte, a high molecular weight polymer binder having a weight average molecular weight of approximately greater than 75,000 grams / mole (g / mol) but less than or equal to 1,000,000 g / mol, and a low molecular weight non-polar liquid rubber (non-polar elastomer), wherein the low molecular weight non-polar liquid rubber has a weight average molecular weight of approximately 2,000 g / mol to approximately 75,000 g / mol and a viscosity of approximately 1 centipoise (cps) to approximately 100,000 cps.

[0009] The solid electrolyte may include a sulfide-based solid electrolyte (also referred to as a "sulfide solid electrolyte"), an oxide-based solid electrolyte (also referred to as an "oxide solid electrolyte"), a polymer solid electrolyte, a gel electrolyte, or a combination thereof, and the gel electrolyte may include a polymer gel electrolyte. The sulfide-based solid electrolyte may be at least one selected from the following: Li2S-P2S5, Li2S-P2S5-LiX, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z, Li2S-SiS2 ... m S n , Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li3PO4 wherein p and q are positive numbers and M is one of P, Si, Ge, B, Al, Ga, and In p MO q , Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0≤x≤2), and Li 7-x PS 6- x I x (where 0≤x≤2).

[0010] The solid electrolyte membrane may have an ion conductivity of about 0.1 millisiemens / cm (mS / cm) to about 5 mS / cm at 25°C.

[0011] According to another aspect of the present disclosure, an all-solid-state secondary battery includes a positive electrode, a negative electrode current collector, and a solid electrolyte layer disposed between the positive electrode and the negative electrode current collector, wherein the solid electrolyte layer includes the solid electrolyte membrane described above.

[0012] According to another aspect of the present disclosure, an all-solid-state secondary battery includes a positive electrode, a negative electrode current collector, and a solid electrolyte layer arranged between the positive electrode and the negative electrode current collector, wherein the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, the first solid electrolyte layer is in contact with the positive electrode, the second solid electrolyte layer is in contact with the negative electrode, and at least one of the first solid electrolyte layer or the second solid electrolyte layer includes the solid electrolyte membrane described above.

[0013] The negative electrode active material may include a carbon-based carrier and a metal-based negative electrode active material supported on the carbon-based carrier, the metal-based negative electrode active material may include a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof, the metal-based negative electrode active material may have a particle form, the metal-based negative electrode active material may have a particle diameter of about 1 nm to about 200 nm, the carbon-based carrier may have a particle form, and the carbon-based carrier may have a particle diameter of about 10 nm to about 2 μm. As used herein, "carbon-based carrier" is also referred to as "carbon carrier", and "metal-based negative electrode active material" is also referred to as "metal negative electrode active material".

[0014] According to another aspect of the present disclosure, a method for manufacturing a solid electrolyte membrane includes: preparing a composition for forming a solid electrolyte membrane, the composition including a solid electrolyte, a high molecular weight polymer binder, a low molecular weight non-polar liquid rubber, and a solvent; and coating a substrate (base plate) with the composition to form a coated substrate, and drying the coated substrate to manufacture the solid electrolyte membrane on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and other aspects, features and advantages of some embodiments of the present disclosure will become more apparent from the following description considered in conjunction with the accompanying drawings, in which:

[0016] Figure 1 is a graph of stress (megaPascal, MPa) versus strain (percent, %), which illustrates stress variation according to strain from preload (preload) in the solid electrolyte membranes of Example 3 and Comparative Example 3;

[0017] Figure 2 is a graph of stress (megaPascal, MPa) versus strain (percent, %), which illustrates stress variation according to strain in the solid electrolyte membranes of Example 4, Example 5, and Comparative Example 3;

[0018] Figure 3It is a graph of voltage (volts, V) versus capacity (milliampere-hour / gram, mAh / g), and illustrates the results of whether the all-solid-state secondary batteries of Example 6 and Comparative Example 6 operate (work) when charged at 0.33C;

[0019] Figures 4A to 4C A schematic diagram for explaining an embodiment of a process for manufacturing an all-solid-state secondary battery including a first solid electrolyte membrane and a second solid electrolyte membrane;

[0020] Figure 5 A schematic diagram for explaining the structure of one embodiment of an all-solid-state secondary battery using a solid electrolyte membrane; and

[0021] Figure 6 A schematic diagram illustrating the structure of another embodiment of an all-solid-state secondary battery using a solid electrolyte membrane. DETAILED DESCRIPTION

[0022] Embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings, wherein the same reference numerals refer to the same elements throughout. In this regard, the present embodiment may have different forms and should not be construed as being limited to the description set forth herein. Therefore, the following describes the embodiments only by reference to the accompanying drawings to illustrate aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the related enumerated items. Expressions such as "at least one (kind) of..." when before or after a list of elements modify the entire list of elements and do not modify the individual elements of the list.

[0023] As used herein, "about" or "approximately" is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, 20%, 10%, or 5% relative to the stated value.

[0024] Unless otherwise defined, all terms (including technical and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless clearly defined in this article.

[0025] Hereinafter, embodiments are described in detail. However, these embodiments are provided for illustrative purposes only and are not intended to limit the present disclosure, and the present disclosure is limited only by the scope of the appended claims.

[0026] Unless specifically stated otherwise herein, when a part of a layer, film, region, panel, etc. is referred to as being “on” another part, it includes not only the case where the part is directly on the other part but also the case where there is an intermediate part therebetween.

[0027] Unless otherwise specifically stated herein, expressions in the singular may also include expressions in the plural. Unless otherwise specifically stated, "A or B" may mean "including A, including B, or including A and B."

[0028] The term "combination thereof" as used herein may refer to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, etc. of constituent elements. The term "metal" as used herein refers to both metals and metalloids such as silicon and tellurium.

[0029] Unless otherwise defined herein, the particle diameter may be an average particle diameter. In addition, the particle diameter refers to the average particle diameter (D50), and the average particle diameter (D50) refers to the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle diameter (D50) can be measured by using a method widely known in the art, and can be measured, for example, by using a particle size analyzer or by a transmission electron microscope image or a scanning electron microscope image. As another method, a dynamic light scattering measurement device can be used for measurement and data analysis, and the number of particles is counted for each particle size range, and then the average particle diameter (D50) can be obtained by calculation. In some embodiments, the average particle diameter (D50) can be measured by using a laser diffraction method. If measured by a laser diffraction method, for example, the particles to be measured can be dispersed in a dispersion medium, and then can be radiated with an output power of 60W using a commercially available laser diffraction particle size measurement device (e.g., Microtrac MT 3000) with an ultrasonic wave of about 28kHz, and then the average particle diameter (D50) of 50% of the particle diameter distribution in the measurement device can be calculated.

[0030] The term "conjugated diene" as used herein refers to a hydrocarbon-based compound including a structure in which two carbon-carbon double bonds are connected to each other by a carbon-carbon single bond, and the term "conjugated polyene" as used herein refers to a hydrocarbon-based compound including at least three double bonds (e.g., at least three carbon-carbon double bonds), and at least two of the double bonds are conjugated, that is, connected to each other by a carbon-carbon single bond.

[0031] "Non-polar" means generally without a dipole.

[0032] The term “aromatic” as used herein refers to a hydrocarbon-based compound including a cyclic structure having a conjugated π electron system, and the term “aliphatic” as used herein refers to a hydrocarbon-based compound not including the above-described aromatic ring.

[0033] As used herein, the term "comprising unit structures derived from monomers" means that a (co)polymer is a polymer obtained using said monomers and comprises repeating units derived from said monomers. The amount (wt%) of these unit structures can be determined, for example, by using nuclear magnetic resonance (NMR), for example 1 Measured by H-NMR method.

[0034] The term "straight chain" as used herein refers to a form in which carbon atoms constituting the compound are arranged sequentially (continuously), and the term "branched" as used herein refers to a form in which at least one carbon in the compound is bonded to at least three carbon atoms.

[0035] As used herein, the term "block" refers to a structure in which one unit structure is dominant in a certain region (certain region) of a polymer chain, the term "alternating" refers to a structure in which two or more unit structures are alternately combined in a certain region of a polymer chain, and the term "random" refers to a structure in which two or more unit structures are randomly combined in a certain region of a polymer chain. For example, "...AAAA-..." may be a block structure, "...-ABAB-..." may be an alternating structure, and "...-ABBABA-..." may be a random structure. In a polymer having a unit structure consisting of A and B, the block structure may be represented by AB or AB, and the random structure may be represented by A / B. These polymer structures can be confirmed by various known methods such as Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), and Koldhof method. For example, the block structure can be confirmed by the Koldhof method, which involves staining a specific unit structure in a copolymer with osmic acid, and then observing the structure by transmission electron microscopy, etc.

[0036] As used herein, weight average molecular weight is determined by gel permeation chromatography (GPC) using polystyrene standards.

[0037] Glass transition temperature is determined by differential scanning calorimetry (DSC) according to ASTM D3418 at a heating rate of 20°C / min.

[0038] The viscosity values ​​disclosed herein refer to the viscosity at room temperature (25°C).

[0039] As used herein, viscosity is evaluated using a Brookfield viscometer. The Brookfield viscometer is a rotational viscometer that measures the torque value generated when a spindle (spindle) is immersed in a sample and rotated at a constant speed. The measuring device used is a Brookfield Ametex DV Next rheometer, and the measuring conditions are 25 degrees, a spindle 64, and 20 rpm.

[0040] In the present disclosure, the solid content means the total content of the remaining components excluding the solvent.

[0041] Hereinafter, a solid electrolyte membrane according to an embodiment, a method of manufacturing the same, and an all-solid-state secondary battery including the same will be described in more detail with reference to the accompanying drawings.

[0042] When a process for large-area mass production (e.g., a rolling process) is applied when manufacturing a solid electrolyte membrane, after the coating and drying process, the solid electrolyte membrane undergoes a densification process of reducing the pores of the membrane and increasing the density of the membrane through a pressing process. During the densification process, the brittleness of the solid electrolyte membrane increases rapidly, resulting in microcracks or ruptures of the solid electrolyte membrane that are prone to occur. Microcracks or ruptures in the solid electrolyte membrane directly affect the battery cell assembly process, and therefore, it is difficult to perform a rolling process.

[0043] The present disclosure provides a solid electrolyte membrane with improved flexibility by using a high molecular weight polymer binder and a low molecular weight non-polar liquid rubber as a plasticizer in a composition for forming a solid electrolyte membrane. Due to the improved flexibility of the solid electrolyte membrane, the solid electrolyte membrane is easily densified, and therefore the pressing process conditions (process conditions) are relaxed (relaxed), and after the pressing process, the solid electrolyte membrane may have a high density, that is, 90% or more, such as 95% or more, and improved bending strength and toughness. Here, for density, it is based on relative density, which is the ratio of the measured density value of the solid electrolyte membrane material to the theoretical true density (bulk density). As a result, the occurrence of microcracks and ruptures is suppressed even after the densification process, and therefore, an all-solid-state secondary battery with improved battery structure stability can be provided.

[0044] The solid electrolyte membrane according to the embodiment may be a solid electrolyte membrane, which includes: a solid electrolyte; a high molecular weight polymer binder; and a low molecular weight non-polar liquid rubber (non-polar elastomer), wherein the low molecular weight non-polar liquid rubber (non-polar elastomer) has a weight average molecular weight of about 2,000 g / mol to about 75,000 g / mol, for example, about 2,000 g / mol to about 60,000 g / mol, and a viscosity of about 1 cps to about 100,000 cps, or about 2,000 cps to about 100,000 cps. The high molecular weight polymer binder has a weight average molecular weight of about greater than 75,000 g / mol but less than or equal to 1,000,000 g / mol.

[0045] As used herein, the term "low molecular weight non-polar liquid rubber" refers to a non-polar elastomer and a material that is liquid at room temperature (25°C) and has a non-polar property, and is therefore not reactive to the solvent used in forming the solid electrolyte membrane. The low molecular weight non-polar liquid rubber has a low weight average molecular weight, i.e., a weight average molecular weight of about 2,000 g / mol to about 75,000 g / mol, and is non-polar, and therefore has excellent solubility and dispersibility in a solid electrolyte and a solvent such as a non-polar solvent as a component of a composition for forming a solid electrolyte membrane. In addition, the low molecular weight non-polar liquid rubber not only has excellent compatibility with the high molecular weight polymer binder, but also does not evaporate or migrate. As used herein, the term "migration" refers to a phenomenon in which a liquid plasticizer moves between solid electrolyte particles and gathers in a certain position or escapes to the outside of the solid electrolyte membrane during a process of manufacturing a solid electrolyte membrane, such as a pressing process.

[0046] The solid electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, a gel electrolyte, or a combination thereof, and the gel electrolyte may include a polymer gel electrolyte.

[0047] The viscosity of the low molecular weight non-polar liquid rubber may be in the range of about 5 cps to about 100,000 cps, about 50 cps to about 100,000 cps, about 100 cps to about 100,000 cps, about 500 cps to about 100,000 cps, about 1,000 cps to about 100,000 cps, about 5,000 cps to about 90,000 cps, about 7,000 cps to about 85,000 cps, about 10,000 cps to about 80,000 cps, about 10,000 cps to about 70,000 cps, or about 10,000 cps to about 50,000 cps. When the low molecular weight nonpolar liquid rubber has a viscosity within the above range, unlike the low molecular weight solid rubber, the low molecular weight nonpolar liquid rubber has superior properties capable of contributing to the plasticization of the composite electrolyte membrane by penetrating between the high molecular weight polymer binder and the solid electrolyte particles.

[0048] Relative to the total weight of the solid electrolyte membrane, the amount of the low molecular weight non-polar liquid rubber may be 5 wt % or less, or in the range of about 0.1 weight percent (wt %) to about 5 wt %, about 0.2 wt % to about 5 wt %, about 1 wt % to about 5 wt %, or about 1 wt % to about 3 wt %. When the amount of the low molecular weight non-polar liquid rubber is within the above range, a solid electrolyte membrane with improved stretchability can be manufactured.

[0049] The amount of the high molecular weight polymer binder may be 5 wt % or less, or in the range of about 0.1 wt % to about 5 wt %, about 0.2 wt % to about 5 wt %, about 1 wt % to about 5 wt %, or about 1 wt % to about 3 wt %, relative to the total weight of the solid electrolyte membrane. When the amount of the high molecular weight polymer binder is within the above range, a solid electrolyte membrane having excellent adhesion to other substrates can be manufactured.

[0050] The amount of the solid electrolyte in the solid electrolyte membrane may be in the range of about 90 wt % to about 99 wt %, about 91 wt % to about 98 wt %, or about 92 wt % to about 97 wt % relative to the total weight of the solid electrolyte membrane. When the amount of the solid electrolyte is within the above range, an all-solid-state secondary battery with improved rate performance can be manufactured without reducing ionic conductivity.

[0051] The solid electrolyte membrane according to the embodiment may have high ductility and be easily densified while maintaining a density of 60% or more after coating, and thus the pressing process conditions may be relaxed. After pressing, the density of the solid electrolyte membrane may be maintained at 95% or more, and therefore, the solid electrolyte membrane may have improved bending strength and toughness while having high flexibility. Therefore, when the solid electrolyte membrane is used, the manufacturing pressure may be reduced in the battery assembly by a continuous process, and this is suitable for forming a bonding interface between electrodes. As a result, all-solid-state secondary batteries with improved battery structure stability may be easily mass-produced.

[0052] The low molecular weight non-polar liquid rubber may be a low molecular weight rubber having a weight average molecular weight (Mw) in the range of about 2,000 g / mol to about 75,000 g / mol, about 2,000 g / mol to about 60,000 g / mol, about 2,000 g / mol to about 58,000 g / mol, or about 2,000 g / mol to about 55,000 g / mol, for example, in the range of about 5,000 g / mol to about 30,000 g / mol or about 5,000 g / mol to about 20,000 g / mol, and having a glass transition temperature (Tg) of about -95°C to about -6°C or about -85°C to about -10°C. g ), and exists in a highly viscous liquid state at room temperature (25°C). The low molecular weight non-polar liquid rubber may be a non-polar rubber having a composition similar to that of the binder, and therefore has low reactivity with the solid electrolyte, excellent solvent compatibility, and excellent compatibility with the binder polymer chain. In addition, the low molecular weight non-polar liquid rubber has a higher viscosity than the organic monomolecular plasticizer based on phthalate, and therefore, there is almost no evaporation and / or migration problem during the drying / pressing process. When the liquid rubber is used as a plasticizer to manufacture a solid electrolyte membrane together with a sulfide solid electrolyte, flexibility can be improved after the pressing process, and when manufacturing an all-solid-state secondary battery including a double-layer solid electrolyte membrane, interface formation can be smooth, manufacturing pressure can be reduced, and battery performance can be improved.

[0053] In one embodiment, the low molecular weight nonpolar liquid rubber may be, for example, a homopolymer including a unit structure derived from a conjugated diene-based monomer. “Conjugated diene-based monomer” is also referred to as “conjugated diene monomer”.

[0054] In another embodiment, the low molecular weight nonpolar liquid rubber may be a copolymer including a unit structure derived from a first conjugated diene-based monomer and a second aromatic vinyl-based monomer. “Aromatic vinyl-based monomer” is also referred to as “aromatic vinyl monomer”.

[0055] In another embodiment, the low molecular weight nonpolar liquid rubber may be a terpolymer including a unit structure derived from a first monomer based on a conjugated diene, a second monomer based on an aromatic vinyl, and a third monomer based on a conjugated polyene (also referred to as a "conjugated polyene" third monomer).

[0056] The first conjugated diene-based monomer may be an aliphatic conjugated diene-based monomer, and its type is not limited as long as it is an aliphatic conjugated diene-based compound. The aliphatic conjugated diene-based compound may be, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, 1,3-hexadiene, 2-ethyl-1,3-butadiene, 2,4-hexadiene, cyclo-1,3-hexadiene, etc., but the present disclosure is not limited thereto.

[0057] The unit structure derived from the first monomer can give the copolymer a relatively soft property. For example, as the content of the unit structure derived from the first monomer increases, the viscoelastic properties of the copolymer can be improved. When the viscoelastic properties of the copolymer are improved, the adhesion of the low molecular weight non-polar liquid rubber can be increased.

[0058] In the copolymer or homopolymer, the unit structure derived from the first monomer may have various forms. For example, 1,3-butadiene, which is a representative example of aliphatic conjugated diene-based compounds, may have a cis-1,4 structure, a trans-1,4 structure, and / or a vinyl-1,2 structure in the copolymer. In the copolymer, when the proportion of the cis unit structure increases, the crystallinity may increase and the glass transition temperature (T g ) may be reduced. In one or more embodiments, when the proportion of the trans unit structure increases, the crystallinity may decrease. In another embodiment, when the proportion of the vinyl unit structure increases, the glass transition temperature (T g ) may be increased. In this way, the properties of the copolymer can be adjusted depending on the type and ratio of the unit structure derived from the first monomer.

[0059] The second monomer based on aromatic vinyl may be non-polar, and may be, for example, but not limited to, styrene, α-methylstyrene, vinyltoluene, tert-butylstyrene, 1,3-dimethylstyrene, 2,4-dimethylstyrene, and ethylstyrene. The unit structure derived from the second monomer may impart relatively rigid physical properties to the copolymer due to steric hindrance. For example, when the content of the unit structure derived from the second monomer increases, the mechanical properties of the copolymer such as hardness, elasticity, and tensile strength may be improved. The unit structure derived from the second monomer may increase the cohesive strength of the copolymer, thereby imparting adhesion. When the content of the unit structure derived from the second monomer increases, the glass transition temperature (T g However, when the ratio of the unit structure derived from the second monomer is too high, the flexibility of the main chain may be reduced, which may lead to deteriorated mechanical properties or adhesion, or increased viscosity, resulting in reduced usability.

[0060] In an embodiment, the content of the unit structure derived from the second monomer may be in a range of about 15 parts by weight to about 45 parts by weight, about 17.5 parts by weight to about 32.5 parts by weight, about 20 parts by weight to about 30 parts by weight, or about 22.5 parts by weight to about 27.5 parts by weight, relative to 100 parts by weight of the copolymer.

[0061] The content of the unit structure derived from the first monomer may be in the range of about 20 parts by weight to about 60 parts by weight relative to 100 parts by weight of the copolymer. Moreover, the content of the unit structure derived from the third monomer may be in the range of about 20 parts by weight to about 60 parts by weight relative to 100 parts by weight of the copolymer.

[0062] The type of the third monomer based on the conjugated polyene is not limited, as long as it has equal to or more than three double bonds and at least two of the double bonds are conjugated, that is, separated by a single bond. For example, the conjugated polyene compound may be, but is not limited to, myrcene, zingiberene, ocimene, α-farnesene, β-farnesene, lycopene, phytoene, and phytoene. Among these conjugated polyene compounds, there are many environmentally friendly compounds that can be obtained from natural sources.

[0063] The conjugated polyene compound can have a large amount of double bonds (for example, 3-20, 3-15 or 3-10 double bonds), and therefore the unit structure derived therefrom can have various forms. In one or more embodiments, at least three binding sites can be present in a monomer to form a network structure. If necessary, the softening point and the glass transition temperature (Tg) of the copolymer can be regulated using the conjugated polyene compound. g ).

[0064] The unit structure derived from the third monomer may include short chain branches in which double bonds are present. The structure of the copolymer may vary depending on the density of such branches. For example, depending on the unit structure derived from the third monomer, the copolymer may have the characteristics of a linear polymer, a branched polymer, or a star polymer.

[0065] In an embodiment, the unit structure derived from the third monomer may include a double bond. The double bond that may be included in the unit structure derived from the third monomer may impart reactivity to the copolymer. By using the copolymer, adhesion may be increased by chemical bonding, or a specific functional group may be given to the copolymer.

[0066] The third monomer may have at least 10 carbon atoms. Among the conjugated polyene compounds, those having at least 10 carbon atoms may be used as the third monomer to increase the glass transition temperature (T g ) or improve its mechanical properties. In one or more embodiments, the length of the unit structure derived from the third monomer may be relatively increased, and thus, the chain of the copolymer may become flexible.

[0067] Among the conjugated polyene compounds having at least 10 carbon atoms, there are compounds that can significantly improve the adhesion of the copolymer due to a large number of double bonds. When compounds having these properties are used as the third monomer, excellent plasticizer properties and adhesive properties at low temperatures can be achieved.

[0068] The number of carbon atoms of these conjugated polyene compounds may be, but is not limited to, 10 or more, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more. The conjugated polyene compound may have 10 to 50, 10 to 40, or 15 to 40 carbon atoms.

[0069] If necessary, the adhesive properties and plasticizer properties can be controlled by hydrogenating the multiple bonds in the copolymer. For example, the unit structure derived from the second monomer and the third monomer may include multiple bonds, and some of them may be hydrogenated to control the adhesive properties and plasticizer properties.

[0070] In addition to controlling the types and contents of the first, second, and third monomers described above, the properties of the copolymer can be adjusted by controlling the structure of the polymer chain. Depending on the arrangement of the unit structure, the copolymer can have at least one of a block structure, an alternating structure, and a random structure.

[0071] When the copolymer contains a block structure derived from the second monomer, the block structure may exist in a hard glassy form at the use temperature of the final product (product) and may form a cluster by chain entanglement. These clusters may be incompatible with the unit structure derived from the first monomer or the third monomer, and may have deformation stability by forming a three-dimensional network structure through physical crosslinking. The cluster may be due to the glass transition temperature (T g ) or higher, and can easily penetrate into the object (object) to be adhered.

[0072] When the copolymer includes a block structure derived from the first monomer or the third monomer, the copolymer may have elasticity. As a result, the final product may have improved impact resistance and may maintain adhesion even when the object to be adhered undergoes a volume change.

[0073] In an embodiment, the copolymer may include a block structure composed of a unit structure derived from the first monomer or the third monomer at one or both ends of the polymer chain of the copolymer. When the copolymer includes such a block structure at one end thereof, the solid electrolyte membrane manufactured therefrom may have excellent toughness characteristics. The term "toughness" as used herein refers to the total amount of energy applied from the moment an object is deformed until the object is destroyed, and the stronger and more flexible the object, the higher the toughness. In other words, the higher the strain energy per unit volume, the higher the toughness, considering both stress and strain. In some embodiments, depending on the characteristics of the block structure included at one end of the copolymer, the copolymer may have high adhesion.

[0074] In one embodiment, in the copolymer, a block structure including a unit structure derived from the third monomer may be bonded to at least one terminal of a random structure including a unit structure derived from the first monomer and the second monomer.

[0075] In another embodiment, in the copolymer, a block structure including a unit structure derived from the first monomer may be bonded to at least one terminal of a random structure including a unit structure derived from the second monomer and the third monomer.

[0076] When a block structure including a unit structure derived from the first monomer or the third monomer is bonded to at least one end of the random structure described above, the chain structure of the copolymer may be flexible and have a viscous property, and the copolymer may have excellent low-temperature characteristics such as interface resistance at low temperatures.

[0077] In another embodiment, the copolymer may include: a first block including a unit structure derived from the first monomer, a second block including a unit structure derived from the second monomer, and a third block including a unit structure derived from the third monomer. Examples of these copolymers may include those in which the second block and the third block are respectively bonded to both ends of the first block, those in which the first block and the third block are respectively bonded to both ends of the second block, and those in which the first block and the second block are respectively bonded to both ends of the third block.

[0078] Depending on the characteristics of the unit structure constituting the middle block in the copolymer, the adhesive strength, thermal stability, mechanical properties, or solubility of the copolymer as a plasticizer may be controlled.

[0079] When the copolymer contains at least three blocks, the copolymer may have a rigid chain structure, and thus, the final product may have excellent mechanical properties. For example, toughness, maximum stress, elongation at break, etc. may be improved.

[0080] In some embodiments, the copolymer may include a random structure formed by unit structures derived from the first monomer, the second monomer, and the third monomer. When each unit structure of the copolymer forms a random structure, chain flexibility may be improved.

[0081] When the content of the branched copolymer in the copolymer is low, that is, when the linearity of the copolymer is high, the copolymer can adhere quickly. In some embodiments, when the amount of the branched copolymer is large, excellent physical properties can be obtained even when a relatively small amount of binder and / or plasticizer is used.

[0082] In the copolymer, at least a portion of the linear copolymer may be branched (coupled) to form a branched copolymer.

[0083] The amount of the branched copolymer in the copolymer may be in the range of about 5 wt % to about 75 wt %, about 5 wt % to about 70 wt %, about 10 wt % to about 65 wt %, about 15 wt % to about 55 wt %, about 20 wt % to about 45 wt %, or about 25 wt % to about 40 wt %, relative to 100 wt % of the copolymer.

[0084] The content of the branched copolymer can be measured by various known methods. For example, its ratio can be confirmed by gel permeation chromatography (GPC) using a polystyrene standard sample. In the peak observed as a result of GPC measurement, the molecular weight of the branched copolymer is present in a relatively higher region than the region of the linear copolymer. Therefore, the ratio of the branched copolymer can be confirmed by the area ratio of the region with a relatively high molecular weight. In another embodiment, the ratio of the branched copolymer can be indirectly confirmed by the degree of branching obtained by the ratio of the Mooney viscosity to the solution viscosity.

[0085] The total content of the unit structure derived from the first monomer and the third monomer may be 60 wt % or more, in the range of about 60 wt % to about 90 wt %, about 5 wt % to about 85 wt %, or in the range of about 5 wt % to about 70 wt %, for example, 60 wt %, 62.5 wt %, 65 wt %, 67.5 wt %, 70 wt %, 72.5 wt %, 75 wt %, 77.5 wt %, 80 wt %, 82.5 wt %, 85 wt %, 87.5 wt %, or 90 wt %, or in the range between the above values, relative to 100 wt % of the unit structure of the copolymer. This content may be selected depending on the conditions of use of the copolymer and its effect.

[0086] The copolymer according to another embodiment may include two unit structures derived from the first monomer, the second monomer, and the third monomer. Such a copolymer may include, for example, a unit structure derived from the first monomer and the second monomer, the first monomer and the third monomer, or the second monomer and the third monomer.

[0087] These unit structures may have a random structure, or the copolymer may be a diblock copolymer having blocks composed of each unit structure, or may be a triblock copolymer in which additional unit structure blocks are respectively bonded to both terminals of one unit structure block.

[0088] The method for preparing the copolymer described above may include preparing the copolymer by polymerizing a linear conjugated diene-based monomer (aliphatic conjugated diene-based first monomer), an aromatic vinyl-based second monomer (non-polar aromatic vinyl-based second monomer), and a branched conjugated polyene-based third monomer (conjugated polyene-based third monomer) constituting the copolymer.

[0089] The properties of the first monomer, the second monomer, the third monomer, and the copolymer may be as described above.

[0090] In the preparation method, an anionic polymerization initiator may be used as a catalyst. As the anionic polymerization initiator, for example, an organic lithium compound such as n-butyl lithium may be used, but the present disclosure is not limited thereto.

[0091] In some embodiments, a randomizing agent may be further included during polymerization to form a random structure. The randomizing agent may be used to activate anionic polymerization initiators, control the polymerization reaction rate of each monomer, and control the ratio of unit structure. Such a randomizing agent may be a reagent commonly used in anionic polymerization, for example, di-tetrahydrofurfurylpropane (di-tetrahydrofuranylpropane), but the present disclosure is not limited thereto.

[0092] In one or more embodiments, a coupling agent may be further included during polymerization to increase the branching degree of the copolymer. Examples of the coupling agent may include, but are not limited to, carbonate-based compounds, chlorosilane-based compounds, ester-based compounds, and divinylbenzene.

[0093] The structure of the copolymer can be changed depending on the difference in the reactivity of the monomers. For example, when multiple monomers are polymerized simultaneously, the unit structure derived from the monomer with a relatively slow reaction rate can form a block structure at the end of the copolymer. The order of the reaction of each monomer can be changed depending on the structural properties of the target copolymer.

[0094] For example, when the first monomer and the second monomer are prepolymerized and then the third monomer is added and polymerized, a block structure including a unit structure derived from the third monomer may be formed at the end of the copolymer. In another embodiment, when the first monomer and the third monomer are prepolymerized and then the second monomer is added and polymerized, a block structure including a unit structure derived from the second monomer may be formed at the end of the copolymer.

[0095] In another embodiment, when one of the first monomer, the second monomer, and the third monomer is polymerized and then the others are added, a block structure may be easily formed.

[0096] In an embodiment, the low molecular weight non-polar liquid rubber may be, for example, liquid butadiene rubber (BR), liquid isoprene rubber (IR), liquid styrene butadiene rubber (SBR), liquid natural rubber (NR), liquid acrylonitrile-butadiene rubber, liquid isobutylene-isoprene rubber, liquid isoprene propylene rubber, liquid styrene-butadiene-farnesene copolymer, a copolymer in which a farnesene block is formed at the end of a styrene-butadiene random structure, a copolymer in which a butadiene block is formed at the end of a styrene-farnesene random copolymer, or a combination thereof. The liquid NR, the liquid IR, or a combination thereof (NR / IR) may have a weight average molecular weight of about 5,000 g / mol to about 54,000 g / mol and a glass transition temperature of about -63°C. In an embodiment, the liquid BR may have a weight average molecular weight of about 5,000 g / mol to about 45,000 g / mol and a glass transition temperature of about -95°C. In other embodiments, the liquid BR may have a weight average molecular weight of about 5,000 g / mol to 9,000 g / mol and a glass transition temperature of about -85°C to about -49°C.

[0097] The liquid SBR may have a weight average molecular weight of about 8,500 g / mol to about 10,000 g / mol and a glass transition temperature of about -14°C to about -6°C.

[0098] The copolymer used as the low molecular weight non-polar liquid rubber may be a block copolymer or a random copolymer. The liquid styrene-butadiene-farnesene copolymer may be, for example, a block copolymer or a random copolymer. The copolymer in which a farnesene block is formed at the end of the styrene-butadiene random structure may be, for example, S / BF 244, the copolymer in which a butadiene block is formed at the end of the styrene-farnesene random copolymer may be S / FB 442, and the liquid styrene-butadiene-farnesene block copolymer may be, for example, SBF 226.

[0099] The high molecular weight polymer binder may have a molecular weight greater than about 75,000 g / mol but less than or equal to about 1,000,000 g / mol, about 80,000 g / mol to about 1,000,000 g / mol, about 100,000 g / mol to about 1,000,000 g / mol, for example, about 100,000 g / mol to about 800,000 g / mol, about 150,000 g / mol to about 75 The weight average molecular weight of the high molecular weight polymer binder is preferably about 0,000 g / mol, about 200,000 g / mol to about 700,000 g / mol, about 250,000 g / mol to about 650,000 g / mol, about 300,000 g / mol to about 600,000 g / mol, about 350,000 g / mol to about 550,000 g / mol, or about 400,000 g / mol to about 500,000 g / mol. When the weight average molecular weight of the high molecular weight polymer binder is within the above range, a solid electrolyte membrane having excellent adhesion to other substrates can be manufactured.

[0100] The high molecular weight polymer binder may be, for example, polyacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide (ethylene oxide), polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, hydrogenated nitrile rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, a copolymer including a unit structure derived from a non-polar monomer and at least one polar monomer selected from a nitrile-based monomer and a (meth)acrylic monomer, an ethylene vinyl acetate copolymer, or a combination thereof.

[0101] The hydrogenated nitrile rubber (H-NBR) may have a degree of hydrogenation of about 99% or greater, a nitrile content of about 17% by weight, and a weight average molecular weight of about 300,000 g / mol to about 1,000,000 g / mol, for example, about 300,000 g / mol to about 800,000 g / mol, about 300,000 g / mol to about 700,000 g / mol, about 300,000 g / mol to about 600,000 g / mol, or about 400,000 g / mol to about 500,000 g / mol.

[0102] The weight ratio of the high molecular weight polymer binder to the low molecular weight non-polar liquid rubber may vary depending on the composition of the polymer binder and the liquid rubber. The weight ratio of the high molecular weight polymer binder to the low molecular weight non-polar liquid rubber may be, for example, in the range of about 1:9 to about 9:1, about 1:7 to about 7:1, about 1:5 to about 5:1, or about 1:1 to about 5:1. When the weight ratio is within the above range, a strong solid electrolyte membrane with improved ductility and bending strength can be obtained without reducing ionic conductivity.

[0103] The total amount of the high molecular weight polymer binder and the low molecular weight non-polar liquid rubber in the solid electrolyte membrane may be in the range of about 1 part by weight to about 5 parts by weight, about 1.2 parts by weight to about 4.5 parts by weight, or about 1.3 parts by weight to about 3 parts by weight, relative to the total weight of 100 parts by weight of the solid electrolyte membrane. When the total amount of the high molecular weight polymer binder and the low molecular weight non-polar liquid rubber is within the above range, a solid electrolyte membrane having excellent ionic conductivity and improved ductility, bending strength and toughness may be manufactured.

[0104] The solid electrolyte membrane may further include at least one of a dispersant, a leveling agent, or a defoaming agent.

[0105] The dispersant is used to uniformly disperse the components of the solid electrolyte membrane.

[0106] As the dispersant, anionic compounds, cationic compounds, nonionic compounds or polymer compounds can be used. The dispersant can be selected depending on the solid electrolyte particles used. The amount of the dispersant in terms of solids of the slurry for forming a solid electrolyte membrane can be 10 parts by weight or less relative to 100 parts by weight of solid electrolyte particles, or in the range of about 0.1 parts by weight to about 5 parts by weight or about 0.3 parts by weight to about 2 parts by weight, or in the range of not affecting battery characteristics.

[0107] The leveling agent may be an alkyl-based surfactant, a silicon-based surfactant, a fluorine-based surfactant, a metal-based surfactant, etc. By mixing the surfactant, cratering that occurs when the solid electrolyte slurry is applied can be prevented, and the smoothness can be improved. The amount of the leveling agent in terms of solids for forming a slurry for a solid electrolyte membrane may be 10 parts by weight or less, or 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of solid electrolyte particles, or within a range that does not affect battery characteristics. The defoamer may be a mineral oil-based defoamer, a silicon-based defoamer, or a polymer-based defoamer. The defoamer may be selected depending on the solid electrolyte particles used. The amount of the defoamer in terms of solids for forming a slurry for a solid electrolyte membrane may be 10 parts by weight or less, or 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of solid electrolyte particles, or within a range that does not affect battery characteristics.

[0108] The solid electrolyte membrane may have a thickness of about 10 micrometers (μm) to about 150 μm, about 15 μm to about 100 μm, about 20 μm to about 100 μm, or about 30 μm to about 100 μm. When the thickness of the solid electrolyte membrane is within the above range, an all-solid-state secondary battery with excellent high rate performance and cycle characteristics can be manufactured.

[0109] The solid electrolyte of the solid electrolyte membrane may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, a gel electrolyte, or a combination thereof, and the gel electrolyte may include a polymer gel electrolyte.

[0110] The solid electrolyte of the solid electrolyte membrane may have a crystalline structure. Here, the crystalline structure may be interpreted as also including a crystalline like structure.

[0111] The sulfide-based solid electrolyte can be prepared by, for example, treating starting materials such as Li2S, P2S5, etc., through melt quenching, mechanical grinding, etc. In another embodiment, after such treatment, heat treatment may be performed. The sulfide-based solid electrolyte may be amorphous or crystalline, or in a mixed state.

[0112] The sulfide-based solid electrolyte may have a crystalline structure. The sulfide-based solid electrolyte may be, for example, an argyrodite-type compound.

[0113] In one or more embodiments, the sulfide-based solid electrolyte may include, for example, at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements in the sulfide-based solid electrolyte material described above. For example, the sulfide-based solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material including Li2S-P2S5, the mixing molar ratio of Li2S to P2S5 may be, for example, in the range of about 50:50 to about 90:10.

[0114] The sulfide-based solid electrolyte may be, for example, a thiogermanate compound including at least one selected from the following: Li where 0 ≤ x ≤ 2 7-x PS 6-x Cl x 、Li where 0 ≤ x ≤ 2 7-x PS 6-x Br x 、and Li where 0 ≤ x ≤ 2 7- x PS 6-x I x 。The sulfide-based solid electrolyte included as the solid electrolyte may be, for example, a thiogermanate compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0115] For example, the sulfide-based solid electrolyte may include a solid electrolyte represented by Formula 1:

[0116] Formula 1

[0117] Li + 12-n-z A n+ B 2- 6-z Y' - z

[0118] Wherein, in Formula 1,

[0119] A may be P, As, Ge, Ga, Sb, Si, Sn, Al, In, Tl, V, Nb, or Ta,

[0120] B may be S, Se, or Te,

[0121] Y' may be Cl, Br, I, F, CN, OCN, SCN, or N3, and

[0122] 1 < n < 5 and 0 < z < 2.

[0123] The sulfide-based solid electrolyte may be a crystalline argyrodite-type solid electrolyte. The crystalline argyrodite-type solid electrolyte may be obtained by heat treatment at a high temperature of 550 °C or higher. For example, the crystalline argyrodite-type solid electrolyte may include at least one selected from the following: Li where 0 < x < 2 7-x PS 6-x Cl x 、Li where 0 < x < 2 7-x PS 6-x Br x 、and Li where 0 < x < 2 7-x PS 6-x I x 。For example, the crystalline argyrodite-type solid electrolyte may include at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I. The crystalline argyrodite-type solid electrolyte may have an elastic modulus of, for example, 15 GPa or greater.

[0124] The sulfide-based solid electrolyte may be, for example, at least one selected from 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 where m and n are positive numbers and Z is Ge, Zn, or Ga m S n ,Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q ,Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 < x ≤ 2), and Li 7-x PS 6-x I x (where 0 < x ≤ 2).

[0125] The solid electrolyte may be, for example, an oxide-based solid electrolyte. The oxide-based solid electrolyte may be at least one selected from the following: Li 1+x+y Al xTi 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (where 0 ≤ x < 1 and 0 ≤ y < 1), Pb(Mg 1 / 3 Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3 (where 0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (where 0 < x < 2, 0 < y < 1, and 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, and Li 3+x La3M2O 12 (where M = Te, Nb, or Zr, and x is an integer from 1 to 10). The solid electrolyte can be prepared by a sintering method or the like. For example, the oxide - based solid electrolyte can be selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M - doped LLZO, M = Ga, W, Nb, Ta, or Al, and x is an integer from 1 to 10, and 0 < a < 2) garnet - type solid electrolytes.

[0126] The solid polymer electrolyte may include, for example, a mixture of a lithium salt and a polymer, or a polymer having an ion-conducting functional group. The solid polymer electrolyte may be, for example, a polyelectrolyte in a solid state at 25° C. and 1 atmosphere (atm). The solid polymer electrolyte may not include, for example, a liquid. The solid polymer electrolyte may include a polymer, and examples of the polymer may include polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methyl methacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(arylene ether ketone) (SPAEK), poly[bis(benzimidazolylbenzissoquinolinone)] (SPBIBI), or a combination thereof. However, the present disclosure is not limited thereto, and any solid electrolyte used in the art is possible. The lithium salt may be any lithium salt that may be used in the art. The lithium salt may be, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, Li(FSO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C4F9SO3) wherein x and y are each 1 to 20 x F 2x+1 SO2)(C y F 2y+1 SO2), LiCl, Lil, mixtures thereof, and the like. The polymer included in the solid polymer electrolyte may be, for example, a compound containing 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the solid polymer electrolyte may be, for example, 1,000 Daltons or more, 10,000 Daltons or more, 100,000 Daltons or more, or 1,000,000 Daltons or more.

[0127] The gel electrolyte may be, for example, a polymer gel electrolyte. For example, the gel electrolyte may be in a gel state without including a polymer.

[0128] For example, the polymer gel electrolyte may include a liquid electrolyte and a polymer, or may include an organic solvent and a polymer having an ion-conducting functional group. The polymer gel electrolyte may be, for example, a polyelectrolyte that is in a gel state at 25° C. and 1 atmosphere. For example, the polymer gel electrolyte may not include a liquid and may be in a gel state. The liquid electrolyte used in the polymer gel electrolyte may be, for example: a mixture of an ionic liquid, a lithium salt, and an organic solvent; a mixture of a lithium salt and an organic solvent; or a mixture of an ionic liquid and an organic solvent. The polymer used in the polymer gel electrolyte may be selected from the polymer used in the solid polymer electrolyte. The organic solvent may be selected from the organic solvent used in the liquid electrolyte. The lithium salt may be selected from the lithium salt used in the solid polymer electrolyte. An ionic liquid may refer to a salt that is in a liquid state at room temperature or a room temperature molten salt that has a melting point below room temperature and includes ions. The ionic liquid may include, for example, at least one selected from the following compounds: a) at least one cation selected from the following: an ammonium-based cation, a pyrrolidine-based cation Cations based on pyridine Cationic, pyrimidine-based Cation, imidazole-based Cation, based on piperidine Cations based on pyrazole Cations, based on Azoles Cationic, pyridazine-based Cations, based on cations based on sulfonium, cations based on triazole cations, and mixtures thereof; and b) at least one anion selected from the following: BF4 - PF6 - 、AsF6 - 、SbF6 - 、AlCl4 - 、HSO4 - 、ClO4 - 、CH3SO3 - CF3CO2 - , Cl - Br - ,I - 、SO4 2- CF3SO3 - 、(FSO2)2N - 、(C2F5SO2)2N - 、(C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N -. For example, the solid polymer electrolyte may be impregnated into a liquid electrolyte in a secondary battery, thereby forming a polymer gel electrolyte. The polymer gel electrolyte may further include inorganic particles. The polymer included in the polymer gel electrolyte may be, for example, a compound containing 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer gel electrolyte may be, for example, 500 Daltons or more, 1,000 Daltons or more, 10,000 Daltons or more, 100,000 Daltons or more, or 1,000,000 Daltons or more.

[0129] The solid electrolyte membrane may have an ionic conductivity of about 0.1 mS / cm to about 5 mS / cm, about 0.15 mS / cm to about 5 mS / cm, about 0.2 mS / cm to about 4 mS / cm, about 0.25 mS / cm to about 4 mS / cm, about 0.3 mS / cm to about 3 mS / cm, or about 0.34 mS / cm to about 3 mS / cm at 25°C.

[0130] The solid electrolyte membrane may have an ionic conductivity of about 0.1 mS / cm to about 5 mS / cm at 25°C, and a strain rate of 0.095% or more, 0.099% or more, or 0.1% or more, or in the range of about 0.1% to about 0.3%. The solid electrolyte membrane may have a Young's modulus of about 10 GPa to about 20 GPa or about 12 GPa to about 16 GPa. When the Young's modulus and the strain rate are within the above range, the flexibility of the solid electrolyte membrane may be improved. The strain rate of the solid electrolyte membrane may be evaluated using the ratio of the bending length to the span width (14 mm) as described in Evaluation Example 2 to be described below. Mechanical properties such as strain rate are highly dependent on the density (or porosity) of the solid electrolyte membrane, and the strain rate of a membrane having a density of at least 95% after pressing can be measured. The strain rate of the solid electrolyte membrane without pressing immediately after coating corresponding to a relative density of about 60% is higher than the strain rate of the solid electrolyte membrane after pressing.

[0131] Hereinafter, a method of manufacturing a solid electrolyte membrane according to an embodiment will be described as follows.

[0132] A solid electrolyte membrane according to an embodiment can be manufactured as follows: preparing a composition for forming a solid electrolyte membrane, the composition including a solid electrolyte, a high molecular weight polymer binder, a low molecular weight non-polar liquid rubber, and a solvent; and coating a substrate with the composition to form a coated substrate, and drying the coated substrate to form the solid electrolyte membrane on the substrate.

[0133] The composition for forming a solid electrolyte membrane may further include at least one of a dispersant, a leveling agent, or a defoaming agent.

[0134] Based on 100 wt % of the composition for forming a solid electrolyte membrane, the solid content of the composition for forming a solid electrolyte membrane may be in the range of about 40 wt % to about 70 wt % or about 50 wt % to about 70 wt %. When the solid content of the composition for forming a solid electrolyte membrane is within the above range, the viscosity stability of the solid electrolyte slurry can be maintained during film formation, thereby achieving excellent film formation. The composition for forming a solid electrolyte membrane suitable for excellent film formation may have a viscosity of about 1,000 cps to about 7,000 cps, for example, about 3,000 cps to about 5,000 cps.

[0135] The solvent may include at least one selected from the group consisting of isobutyl isobutyrate, n-butyl butyrate, 2-ethylhexyl acetate, octyl acetate, ethyl hexanoate, diisobutyl ketone, n-heptyl acetate, hexyl acetate, d-limonene, trimethylbenzene, and cumene. For example, the solvent may include at least one selected from the group consisting of 2-ethylhexyl acetate, hexyl acetate, and cumene.

[0136] Figures 4A to 4C 1 is a diagram for explaining a method of manufacturing an all-solid-state secondary battery and an all-solid-state secondary battery manufactured therefrom according to an embodiment. The all-solid-state secondary battery may include first and second solid electrolyte membranes 30a and 30b.

[0137] like Figure 4A As shown in , first, the first solid electrolyte membrane 30a can be stacked on the positive electrode 10 including the positive electrode current collector 11 and the positive electrode active material layer 12 to prepare the first laminate. The first laminate can be subjected to a first pressing. The first solid electrolyte membrane 30a may include a first solid electrolyte and a first polymer binder. The first pressing may be, for example, roll pressing, uniaxial pressing, flat pressing, warm isostatic pressing (WIP), cold isostatic pressing (CIP), etc. The pressure applied during pressing may be, for example, greater than 300MPa and less than or equal to 750MPa. The pressure may be applied for about 5ms to about 60 minutes. The pressing may be performed at a temperature of, for example, from about room temperature to about 90°C or from about 20°C to about 90°C. In another embodiment, the pressing may be performed at a high temperature of 100°C or higher. For example, the first pressing may be performed at a temperature of about 80°C to about 90°C, or 85°C and a pressure of about 400MPa to about 600MPa, about 450MPa to about 550MPa, or 500MPa.

[0138] Separately, the first negative active material layer 22 may be stacked on the negative current collector 21 to form the negative electrode 20 .

[0139] The second solid electrolyte membrane 30b and the negative electrode 20 may be disposed on the first solid electrolyte membrane 30a of the first laminate to prepare a second laminate. The second solid electrolyte membrane 30b may include a second solid electrolyte, a high molecular weight polymer binder, and a low molecular weight nonpolar liquid rubber, and thus has excellent flexibility.

[0140] The second laminate may be subjected to a second pressing, thereby completing the manufacture of the all-solid-state secondary battery according to the embodiment. The second pressing may be performed using the pressing process used in the first pressing, and may be performed under conditions that are relaxed compared to the first pressing. The pressure applied during the second pressing may be in the range of, for example, about 150MPa to about 300MPa. The pressure may be applied for about 5ms to about 60 minutes. The pressing may be performed at a temperature of, for example, about room temperature to about 90°C or about 20°C to about 90°C. In another embodiment, the pressing may be performed at a high temperature of 100°C or higher. For example, the second pressing may be performed at a temperature of about 80°C to about 90°C, or 85°C and a pressure of about 200MPa to about 250MPa.

[0141] A method of manufacturing an all-solid secondary battery according to another embodiment will be described as follows: The first stacked body may be manufactured in the manner described above.

[0142] The second solid electrolyte film 30b can be stacked on the negative electrode 20 including the negative electrode current collector 21 and the first negative electrode active material layer 22 to prepare a second stack. The second stack can be subjected to a second pressing. The second solid electrolyte film 30b may include a second solid electrolyte, a high molecular weight polymer binder, and a low molecular weight non-polar liquid rubber, and therefore has excellent flexibility. In the second pressing, the same pressing process as used in the first pressing can be used. The first stack and the second stack can be adhered to each other, followed by a third pressing, so as to complete the manufacture of the all-solid-state secondary battery according to the embodiment. The third pressing can be performed using the pressing process used in the first pressing or the second pressing, and can be performed under conditions of relaxation compared to the first pressing or the second pressing. The all-solid-state secondary battery can be manufactured under no pressure by a stacking method without additional pressing.

[0143] In another embodiment, the second solid electrolyte membrane 30 b having excellent flexibility by including a low molecular weight nonpolar liquid rubber may be stacked on the positive electrode 10 , thereby forming a first stacked body.

[0144] like Figure 4CAs shown in , when the second solid electrolyte membrane 30b is in contact with the negative electrode, even when the volume or thickness of the negative electrode changes during charging and discharging, the adhesion between the negative electrode and the second solid electrolyte membrane can be well maintained, and it is suitable for the formation of a bonding interface even under relatively low second pressing conditions, thereby achieving stable battery operation.

[0145] like Figure 4C As shown in , when the second solid electrolyte membrane 30b is in contact with the negative electrode, good adhesion between the first stack and the second stack can be formed even under relatively low third pressing conditions, and it is suitable for long-term maintenance of the bonding interface, thereby achieving more stable battery operation.

[0146] According to an embodiment, an all-solid-state secondary battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane disposed therebetween, wherein the solid electrolyte membrane includes the solid electrolyte membrane according to the embodiment.

[0147] The negative electrode may include a negative electrode collector and a first negative electrode active material layer, and the first negative electrode active material layer may include a carbon-based negative electrode active material, a first metal, a metalloid, or a combination thereof.

[0148] The all-solid-state secondary battery may further include a second negative electrode active material layer between the negative electrode collector and the first negative electrode active material layer, and the second negative electrode active material layer may include a second metal material.

[0149] The second metal material may be lithium, a second metal, a lithium alloy of lithium and the second metal, or a combination thereof.

[0150] The second metal may include at least one of silver (Ag), tin (Sn), indium (In), silicon (Si), gallium (Ga), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), magnesium (Mg), cesium (Cs), cerium (Ce), lanthanum (La), tungsten (W), tellurium (Te), or an alloy thereof.

[0151] The lithium alloy may include: lithium; and silver (Ag), tin (Sn), indium (In), silicon (Si), gallium (Ga), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), magnesium (Mg), cesium (Cs), cerium (Ce), lanthanum (La), tungsten (W), tellurium (Te), or a combination thereof.

[0152] According to another embodiment, a binder for a solid electrolyte membrane includes a first binder and a second binder having different binding energies for a sulfide-based solid electrolyte, the binding energy of the first binder for the sulfide-based solid electrolyte being less than -300,000 kcal / mol, and the binding energy of the second binder for the sulfide-based solid electrolyte being in the range of about -300,000 kcal / mol to about -50,000 kcal / mol.

[0153] Figure 5 and 6 It is a diagram for explaining an all-solid-state secondary battery 1 according to an embodiment.

[0154] refer to Figure 5 and 6 The all-solid-state secondary battery 1 is a secondary battery using a solid electrolyte membrane as an electrolyte.

[0155] The all-solid-state secondary battery 1 may include a positive electrode 10 , a solid electrolyte membrane 30 , and a negative electrode 20 .

[0156] positive electrode

[0157] The positive electrode 10 may include a positive electrode current collector 11 and a positive electrode active material layer 12 .

[0158] The positive electrode current collector 11 may be a plate, foil, etc. made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or any alloy thereof.

[0159] The positive electrode active material layer 12 may include, for example, a positive electrode active material.

[0160] The positive electrode active material may be a positive electrode active material capable of reversible insertion and extraction of lithium ions. The positive electrode active material may be, but is not limited to, for example, a lithium transition metal oxide such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, or lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, and any positive electrode active material that can be used in the art is possible. These positive electrode active materials may be used alone, or a mixture of at least two thereof may be used.

[0161] The positive electrode active material may include, for example, a compound represented by one of the following formulae: Li a A 1-b B bD2 (where 0.90≤a≤1 and 0≤b≤0.5); Li a E 1-b B b O 2-c D c (where 0.90≤a≤1, 0≤b≤0.5, and 0≤c≤0.05); 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, 0≤b≤0.5, 0≤c≤0.05, and 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α F α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b-c Co b B c O 2-α F2 (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b- c Mn b B c D α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α≤2); Li a Ni 1-b-c Mn b B c O 2-α F α (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α F2 (where 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, and 0<α<2); Li a Ni b E c G dO2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, and 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2 (where 0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0.001≤e≤0.1); Li a NeG b O2 (where 0.90≤a≤1 and 0.001≤b≤0.1); Li a CoG b O2 (where 0.90≤a≤1 and 0.001≤b≤0.1); Li a MnG b O2 (where 0.90≤a≤1 and 0.001≤b≤0.1); Li a Mn b O4 where 0.90≤a≤1 and 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(where 0≤f≤2);Li (3-f)Fe2(PO4)3 (wherein 0≤f≤2); and LiFePO4. In the formulas of these compounds, A may be nickel (Ni), cobalt (Co), manganese (Mn), or a combination thereof, B may be aluminum (Al), Ni, Co, Mn, chromium (Cr), iron (Fe), magnesium (Mg), strontium (Sr), vanadium (V), a rare earth element, or a combination thereof, D may be oxygen (O), fluorine (F), sulfur (S), phosphorus (P), or a combination thereof, E may be Co, Mn, or a combination thereof, F may be F, S, P, or a combination thereof, G may be Al, Cr, Mn, Fe, Mg, lanthanum (La), cerium (Ce), Sr, V, or a combination thereof, Q may be titanium (Ti), molybdenum (Mo), Mn, or a combination thereof, I may be Cr, V, Fe, scandium (Sc), yttrium (Y), or a combination thereof, and J may be V, Cr, Mn, Co, Ni, copper (Cu), or a combination thereof. The above-mentioned compounds having a coating layer on the surface can be used, or a mixture of the above-described compounds and other compounds having a coating layer can be used. The coating layer provided on the surface of the above-described compound may include, for example, a coating element compound, such as an oxide of a coating element, a hydroxide of a coating element, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a hydroxycarbonate of a coating element. The compound constituting the coating layer may be amorphous or crystalline. The coating element included in the coating layer may be Mg, Al, Co, potassium (K), sodium (Na), calcium (Ca), silicon (Si), Ti, V, tin (Sn), germanium (Ge), gallium (Ga), boron (B), arsenic (As), zirconium (Zr), or a mixture thereof. The coating layer formation method may be selected from a method that does not adversely affect the physical properties of the positive active material. The coating layer formation method may be, for example, spraying, dipping, etc. The coating layer formation method will be clear to those of ordinary skill in the art, and therefore, a detailed description thereof will not be provided herein.

[0162] The positive electrode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The term "layered rock salt type structure" may refer to, for example, a structure in which oxygen atomic layers and metal atomic layers are arranged in a cubic rock salt type structure. <111> The term "cubic rock salt type structure" refers to a sodium chloride (NaCl) type structure as a type of crystal structure, and, for example, refers to a structure in which a face-centered cubic (fcc) lattice formed by cations and anions, respectively, is offset by only half of the ridge of each unit lattice (unit cell). The lithium transition metal oxide having such a layered rock salt type structure may be, for example, a ternary lithium transition metal oxide such as LiNi x Co y Al z O2(NCA) or LiNix Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1). When the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt structure, the energy density and thermal stability of the all-solid-state secondary battery 1 can be further improved.

[0163] The positive electrode active material may be covered with the coating layer as described above. The coating layer may be any coating layer known as a coating layer for a positive electrode active material of an all-solid-state secondary battery. The coating layer may be, for example, Li2O-ZrO2 or the like.

[0164] When the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, the capacity density of the all-solid-state secondary battery 1 can be increased, and thus, the elution of metal from the positive electrode active material in the charged state can be reduced. As a result, the all-solid-state secondary battery 1 can have improved cycle characteristics.

[0165] The positive electrode active material may have a particle shape, such as a true spherical shape, an ellipsoidal shape, or a spherical shape. The particle diameter of the positive electrode active material is not limited and is within the range suitable for positive electrode active materials used in existing all-solid-state secondary batteries. The amount of the positive electrode active material in the positive electrode 10 is not limited and can be within the range suitable for positive electrodes of existing all-solid-state secondary batteries.

[0166] In addition to the positive electrode active material described above, the positive electrode 10 may further include, for example, additives such as a conductive agent, a binder, a filler, a dispersant, and an ion conduction aid. Non-limiting examples of these conductive agents may include graphite, carbon black, acetylene black, Ketjen black, carbon nanotubes, carbon nanofibers, and metal powders. The binder may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc. As fillers, dispersants, ion conduction aids, etc. that can be mixed during the manufacture of the positive electrode 10, known materials commonly used in electrodes of all-solid-state secondary batteries can be used.

[0167] The positive electrode 10 may further include a solid electrolyte. The solid electrolyte included in the positive electrode 10 may be similar (the same) or different from the solid electrolyte included in the solid electrolyte membrane 30. The solid electrolyte may refer to the detailed description provided above for the solid electrolyte membrane 30.

[0168] The solid electrolyte included in the positive electrode 10 may be, for example, a sulfide-based solid electrolyte. As the sulfide-based solid electrolyte, the sulfide-based solid electrolyte used in the solid electrolyte membrane 30 can be used.

[0169] In another embodiment, the positive electrode 10 may be impregnated with, for example, a liquid electrolyte. The liquid electrolyte may include a lithium salt and at least one of an ionic liquid and a polymer ionic liquid. The liquid electrolyte may be non-volatile. The ionic liquid may refer to a salt in a liquid state at room temperature or a room temperature molten salt, which has a melting point below room temperature and includes ions. The ionic liquid may be one selected from the following compounds: a) at least one cation selected from the following: ammonium-based cations, pyrrolidine-based cations, Cations based on pyridine Cationic, pyrimidine-based Cation, imidazole-based Cation, based on piperidine Cations based on pyrazole Cations, based on Azoles Cationic, pyridazine-based Cations, based on cations based on sulfonium, cations based on triazole cations, and mixtures thereof; and b) at least one anion selected from the following: BF4 - PF6 - 、AsF6 - 、SbF6 - 、AlCl4 - 、HSO4 - 、ClO4 - 、CH3SO3 - CF3CO2 - , Cl - Br - ,I - 、SO4 2- CF3SO3 - 、(FSO2)2N - 、(C2F5SO2)2N - 、(C2F5SO2)(CF3SO2)N - , and (CF3SO2)2N - The ionic liquid may be, for example, at least one selected from the following: bis(trifluoromethanesulfonyl)imide N-methyl-N-propylpyrrolidine Bis(trifluoromethanesulfonyl)imide N-butyl-N-methylpyrrolidine Bis(trifluoromethanesulfonyl)imide 1-butyl-3-methylimidazole and bis(trifluoromethanesulfonyl)imide 1-ethyl-3-methylimidazole The polymeric ionic liquid may contain repeating units comprising: a) at least one cation selected from the group consisting of ammonium-based cations, pyrrolidine-based cations, Cations based on pyridine Cationic, pyrimidine-based Cation, imidazole-based Cation, based on piperidine Cations based on pyrazole Cations, based on Azoles Cationic, pyridazine-based Cations, based on cations based on sulfonium, cations based on triazole cations, and mixtures thereof; and b) at least one anion selected from the following: 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 - CF3(SO2)2CH - 、(SF5)3C - , and (O(CF3)2C2(CF3)2O)2PO -The lithium salt may be any lithium salt that can be used in the art. The lithium salt may be, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, Li(FSO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (wherein x and y are natural numbers), LiCl, LiI, or a mixture thereof. The concentration of the lithium salt included in the liquid electrolyte may be in the range of about 0.1M to about 5M. The amount of the liquid electrolyte impregnated into the positive electrode 10 may be in the range of about 0 parts by weight to about 100 parts by weight, about 0 parts by weight to about 50 parts by weight, about 0 parts by weight to about 30 parts by weight, about 0 parts by weight to about 20 parts by weight, about 0 parts by weight to about 10 parts by weight, or about 0.01 parts by weight to about 5 parts by weight, relative to 100 parts by weight of the positive electrode active material layer 12 not including the liquid electrolyte.

[0170] Solid electrolyte membrane

[0171] The solid electrolyte membrane 30 may be disposed between the cathode 10 and the anode 20 and include the solid electrolyte membrane according to the embodiment.

[0172] negative electrode

[0173] refer to Figure 5 The negative electrode 20 may include a negative electrode current collector 21 and a first negative electrode active material layer 22 .

[0174] The negative electrode current collector 21 may include, for example, a base film and a metal layer on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. By including an insulating thermoplastic polymer, when a short circuit occurs, the base film softens or liquefies, and thus by blocking the battery operation, the rapid increase of the current can be suppressed. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative electrode current collector may further include a metal substrate (chip) and / or a lead tab. For more details about the base film, metal layer, metal substrate, and lead tab of the negative electrode current collector, reference may be made to those provided below with respect to the positive electrode current collector 11. When the negative electrode current collector has this structure, the weight of the negative electrode may be reduced, resulting in improved energy density of an all-solid-state secondary battery.

[0175] The negative electrode current collector 21 may be in the form of, for example, a plate or a foil.

[0176] The first negative active material layer may include a carbon-based negative active material, a first metal, a metalloid, or a combination thereof.

[0177] In the first negative electrode active material layer, the carbon-based negative electrode active material may include amorphous carbon. The amorphous carbon may be, for example, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, carbon nanotubes, carbon nanofibers, etc. However, the present disclosure is not limited thereto, and any carbon classified as amorphous carbon in the art is possible.

[0178] The first metal or metalloid may include, but is not limited to, at least one of the following: indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), or zinc (Zn), and any metal negative electrode active material or metalloid negative electrode active material in the art that forms an alloy or compound with lithium can be used.

[0179] The first negative electrode active material layer may include a negative electrode active material selected from a carbon-based active material and a metal or metalloid negative electrode active material, or may include a mixture of a plurality of different negative electrode active materials. For example, the first negative electrode active material layer may contain only amorphous carbon, or may include at least one metal or metalloid selected from indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), and zinc (Zn). In another embodiment, the first negative electrode active material layer may contain only amorphous carbon, or may include a composite of amorphous carbon and at least one metal or metalloid negative electrode active material selected from the following: indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), and zinc (Zn). The composite ratio of amorphous carbon to metal or metalloid negative electrode active materials such as silver in its composite may be, for example, in the range of about 10:1 to about 1:2, about 5:1 to about 1:1, or about 4:1 to about 2:1 by weight. However, the present disclosure is not limited to this range, and the composite ratio may be selected depending on the desired characteristics of the all-solid-state secondary battery. When the first negative electrode active material layer has such a composition, the cycle characteristics of the all-solid-state secondary battery may be further improved.

[0180] The negative electrode active material included in the first negative electrode active material layer may include, for example, a mixture of first particles composed of amorphous carbon and second particles composed of metal or metalloid. The mixture may be a simple mixture of the first particles and the second particles or a mixture obtained by physical bonding of a binder. The metal or the metalloid may include, for example, at least one selected from the following: indium (In), silicon (Si), gallium (Ga), tin (Sn), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), gold (Au), platinum (Pt), palladium (Pd), magnesium (Mg), silver (Ag), and zinc (Zn). In another embodiment, the metalloid may be a semiconductor. Relative to the total weight of the mixture, the amount of the second particles may be in the range of about 8 wt % to about 60 wt %, about 10 wt % to about 50 wt %, about 15 wt % to about 40 wt %, or about 20 wt % to about 30 wt %. When the amount of the second particles is within the above range, for example, the cycle characteristics of the all-solid secondary battery 1 may be further improved.

[0181] The first negative electrode active material layer may include: i) a composite of first particles composed of amorphous carbon and second particles composed of a metal or a metalloid; or ii) a mixture of first particles composed of amorphous carbon and second particles composed of a metal or a metalloid, and the amount of the second particles may be in the range of about 1 wt% to about 60 wt% relative to the total weight of the composite or the mixture.

[0182] The first negative electrode active material layer may have a thickness of, for example, about 10 nm to about 10 μm, about 100 nm to about 10 μm, about 200 nm to about 10 μm, about 300 nm to about 10 μm, about 400 nm to about 10 μm, about 500 nm to about 10 μm, about 1 μm to about 10 μm, about 1 μm to about 9 μm, about 1 μm to about 8 μm, about 2 μm to about 7 μm, or about 3 μm to about 7 μm. When the thickness of the first negative electrode active material layer is within the above range, short circuit of the all-solid-state secondary battery can be suppressed and its cycle characteristics can be improved.

[0183] In another embodiment, the first negative electrode active material layer 22 may include a composite negative electrode active material. The composite negative electrode active material may include, for example, a carbon-based carrier and a metal-based negative electrode active material supported on the carbon-based carrier. When the composite negative electrode active material has such a structure, localization of the metal-based negative electrode active material in the first negative electrode active material layer can be prevented and its uniform distribution can be obtained. As a result, the cycle characteristics of the all-solid-state secondary battery 1 including the first negative electrode active material layer 22 can be further improved.

[0184] The metal-based negative electrode active material supported on the carbon-based carrier may include, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof. Non-limiting examples of the metal may include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), tellurium (Te), and zinc (Zn). Non-limiting examples of the metal oxide may include gold oxide (Au), platinum oxide (Pt), palladium oxide (Pd), silicon oxide (Si), silver oxide (Ag), aluminum oxide (Al), bismuth oxide (Bi), tin oxide (Sn), tellurium oxide (Te), and zinc oxide (Zn). The metal oxide may include, for example, Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Pd x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), Si x O y(where 0 < x ≤ 1 and 0 < y ≤ 2), Ag x O y (where 0 < x ≤ 2 and 0 < y ≤ 1), Al x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Bi x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Sn x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Te x O y (where 0 < x ≤ 1 and 0 < y ≤ 3), Zn x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), or a combination thereof. The composite of the metal and the metal oxide may include, for example, a composite of Au and Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), a composite of Pt and Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), a composite of Pd and Pd x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), a composite of Si and Si x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), a composite of Ag and Ag x O y (where 0 < x ≤ 2 and 0 < y ≤ 1), a composite of Al and Al x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), a composite of Bi and Bi x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), a composite of Sn and Sn x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), a composite of Te and Te x O y (where 0 < x ≤ 1 and 0 < y ≤ 3), a composite of Zn and Zn x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), or a combination thereof.

[0185] The carbon-based carrier may be, for example, amorphous carbon. The amorphous carbon may be, for example, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, activated carbon, carbon nanofiber (CNF), or carbon nanotube (CNT). However, the present disclosure is not limited thereto, and any carbon classified as amorphous carbon in the art is possible. Amorphous carbon may be carbon without crystallinity or with very low crystallinity and may be distinguished from crystalline carbon or graphite carbon. The carbon-based carrier may be, for example, a carbon-based negative electrode active material.

[0186] The composite negative electrode active material may have, for example, a particle form. The particle diameter of the composite negative electrode active material in particle form may be, for example, in the range of about 10 nm to about 4 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. When the particle diameter of the composite negative electrode active material is within the above range, the reversible absorption and / or desorption of lithium during charging and discharging may be further promoted. The metal-based negative electrode active material supported on the carrier may have, for example, a particle form. The particle diameter of the metal-based negative electrode active material may be, for example, in the range of about 1 nm to about 200 nm, about 1 nm to about 150 nm, about 5 nm to about 100 nm, or about 10 nm to about 50 nm. The carbon-based carrier may have, for example, a particle form. The particle diameter of the carbon-based carrier may be, for example, in the range of about 10 nm to about 2 μm, about 10 nm to about 1 μm, about 10 nm to about 500 nm, about 10 nm to about 200 nm, or about 10 nm to about 100 nm. When the particle diameter of the carbon-based carrier is within the above range, the carbon-based carrier may be more uniformly arranged in the first negative electrode active material layer. The carbon-based carrier may be, for example, nanoparticles having a particle diameter of 500 nm or less. The particle diameter of the composite negative electrode active material, the particle diameter of the metal-based negative electrode active material, and the particle diameter of the carbon-based carrier may be, for example, an average particle diameter. The average particle diameter may be, for example, a median diameter (D50) measured by using a laser particle size distribution analyzer. In another embodiment, the average particle diameter may be automatically determined, for example, by using software from an electron microscope image, or may be manually determined manually by manual means.

[0187] In the all-solid-state secondary battery 1 according to the embodiment, as Figure 6 As shown in , the second negative active material layer 23 may be disposed between the negative current collector 21 and the first negative active material layer 22 .

[0188] The second negative active material layer 23 may be provided during battery assembly, or may not be present during battery assembly and may be formed as a precipitated layer after charging.

[0189] The second negative active material layer may include a second metal material.

[0190] The second metal material may be lithium, a second metal, a lithium alloy of lithium and the second metal, or a combination thereof.

[0191] The second metal may include at least one selected from the following: silver (Ag), tin (Sn), indium (In), silicon (Si), gallium (Ga), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), magnesium (Mg), cesium (Cs), cerium (Ce), lanthanum (La), tungsten (W), tellurium (Te), and alloys thereof.

[0192] The lithium alloy may include: lithium; and silver (Ag), tin (Sn), indium (In), silicon (Si), gallium (Ga), aluminum (Al), titanium (Ti), zirconium (Zr), niobium (Nb), germanium (Ge), antimony (Sb), bismuth (Bi), zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), nickel (Ni), iron (Fe), cobalt (Co), chromium (Cr), magnesium (Mg), cesium (Cs), cerium (Ce), lanthanum (La), tungsten (W), tellurium (Te), or a combination thereof.

[0193] The second negative electrode active material layer may be lithium metal or a second metal applied to the current collector. In another embodiment, the second negative electrode active material layer may be a lithium metal or a lithium alloy layer precipitated during charging. The volume and thickness of the second negative electrode active material layer may increase due to lithium precipitation during charging. In one or more embodiments, the second metal may form a Li-M2 (second metal) alloy by a reversible reaction during charging and discharging of the all-solid-state secondary battery. In the process of charging the all-solid-state secondary battery or setting the all-solid-state secondary battery, or in both processes, the second negative electrode active material layer may be formed as a precipitation layer or a deposition layer, and the second negative electrode active material layer may be a lithium metal layer or a lithium metal alloy layer.

[0194] The second metal in the second negative electrode active material layer may form an alloy with lithium during charging of the all-solid-state secondary battery or during setting of the all-solid-state secondary battery, or both.

[0195] The second negative electrode active material layer may be disposed on the first negative electrode active material layer by pressing, for example, adhered to the first negative electrode active material layer. During the pressing process, some of the lithium contained in the second negative electrode active material layer may be injected into the first negative electrode active material layer.

[0196] Setting (eg, bonding) may be a pressure compression process.

[0197] In another embodiment, in the process of charging the all-solid-state secondary battery or setting the all-solid-state secondary battery, or in both processes, the second negative electrode active material layer may be further formed as a precipitation layer. The second negative electrode active material layer may be a lithium metal layer or a lithium metal alloy layer. The second negative electrode active material layer may have, for example, 1 μm or more, 5 μm or more, or 10 μm or more, or a thickness in the range of about 10 μm to about 1,000 μm, about 10 μm to about 500 μm, about 10 μm to about 200 μm, about 10 μm to about 100 μm, or about 10 μm to about 50 μm.

[0198] Cathode Manufacturing

[0199] The materials constituting the positive electrode active material layer 12, ie, the positive electrode active material, the binder, etc., may be added to a non-polar solvent to prepare a slurry. The prepared slurry may be applied to the positive electrode collector 11 and dried.

[0200] The positive electrode current collector may include, for example, a base film and a metal layer on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The base film may be, for example, an insulator. By including an insulating thermoplastic polymer, when a short circuit occurs, the base film softens or liquefies, and thus by blocking the battery operation, the rapid increase of the current can be suppressed. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The metal layer may be used as an electrochemical fuse and break in the case of an overcurrent, thereby performing a short circuit prevention function. By adjusting the thickness of the metal layer, the limiting current and the maximum current can be adjusted. The metal layer may be plated or deposited on the base film. When the thickness of the metal layer is reduced, the limiting current and / or the maximum current of the positive electrode collector 11 can be reduced, and therefore, the stability of the lithium battery in the case of a short circuit can be improved. A lead tab can be added to the metal layer for connection to the outside. The lead tab can be welded to the metal layer or the metal layer / base film stack by ultrasonic welding, laser welding, spot welding, etc. During welding, when the base film and / or the metal layer melts, the metal layer can be electrically connected to the lead tab. In order to make the welding between the metal layer and the lead tab more rigid, a metal substrate can be added between the metal layer and the lead tab. The metal substrate may be a foil of the same material as the metal of the metal layer. The metal substrate may be, for example, a metal foil or a metal mesh. The metal substrate may be, for example, aluminum foil, copper foil, SUS foil, etc. The lead tab can be welded to the metal substrate / metal layer stack or the metal substrate / metal layer / base film stack by welding to the lead tab after the metal substrate is disposed on the metal layer. During welding, when the base film, the metal layer, and / or the metal substrate melt, the metal layer or the metal layer / metal substrate stack can be electrically connected to the lead tab. The metal substrate and / or the lead tab can be added to a portion of the metal layer. The base film can have a thickness of, for example, about 1 μm to about 50 μm, about 1.5 μm to about 50 μm, about 1.5 μm to about 40 μm, or about 1 μm to about 30 μm. When the thickness of the base film is within the above range, the weight of the positive electrode can be effectively reduced. The base film can have a melting point of, for example, about 100°C to about 300°C, about 100°C to about 250°C, or about 100°C to about 200°C. When the melting point of the base film is within the above range, the base film may be melted and easily bonded to the lead tab during lead tab welding.The base film may be surface treated, such as corona treatment, to improve adhesion between the base film and the metal layer. The metal layer may have a thickness of, for example, about 0.01 μm to about 3 μm, about 0.1 μm to about 3 μm, about 0.1 μm to about 2 μm, or about 0.1 μm to about 1 μm. When the thickness of the metal layer is within the above range, the stability of the positive electrode can be ensured while maintaining conductivity. The metal substrate may have a thickness of, for example, about 2 μm to about 10 μm, about 2 μm to about 7 μm, or about 4 μm to about 6 μm. When the thickness of the metal substrate is within the above range, the connection between the metal layer and the lead pole ear may be further promoted. When the positive current collector 11 has this structure, the weight of the electrode can be reduced, resulting in an improved energy density of an all-solid-state secondary battery.

[0201] The positive electrode current collector may be omitted. The positive electrode current collector may further include a carbon layer disposed on one or both sides of the metal substrate. By further arranging a carbon layer on the metal substrate, the metal of the metal substrate can be prevented from being corroded by the solid electrolyte included in the positive electrode layer, and the interface resistance between the positive electrode active material layer and the positive electrode current collector can be reduced. The carbon layer may have a thickness of, for example, about 0.1 μm to about 5 μm, about 0.1 μm to about 3 μm, or about 0.1 μm to about 1 μm. When the thickness of the carbon layer is too small, it may be difficult to completely block the contact between the metal substrate and the solid electrolyte. When the thickness of the carbon layer is too large, the energy density of the all-solid-state secondary battery may be reduced. The carbon layer may include amorphous carbon, crystalline carbon, and the like.

[0202] The obtained laminate can be pressed to manufacture the positive electrode 10. The pressing can be, for example, pressing using a roller press, a flat press, or a liquid static pressure (hydrostatic pressure). However, the present disclosure is not limited to these methods, and any pressing used in the art is possible. The pressing process can be omitted. The mixture of materials constituting the positive electrode active material layer 12 can be compacted and molded into a disc form or stretched (molded) into a sheet form, thereby completing the manufacture of the positive electrode 10. When the positive electrode 10 is manufactured by this method, the positive electrode collector 11 can be omitted. In another embodiment, the positive electrode 10 can be used after being impregnated with an electrolyte solution.

[0203] Manufacturing of all-solid-state secondary batteries

[0204] The negative electrode 20 , the solid electrolyte membrane 30 , and the positive electrode 10 may be prepared, and the positive electrode 10 and the negative electrode 20 may be stacked with the solid electrolyte membrane 30 interposed therebetween, or may be pressed after stacking to thereby complete the manufacture of the all-solid secondary battery 1 .

[0205] The pressing may be, for example, roll pressing, uniaxial pressing, flat pressing, warm isostatic pressing (WIP), or cold isostatic pressing (CIP). However, the present disclosure is not limited to these methods, and any pressing used in the art is possible. The pressure applied during pressing may be, for example, in the range of about 50MPa to about 750MPa. The pressure may be applied for about 5ms to about 60 minutes. The pressing may be carried out at a temperature of, for example, 90°C or lower, or about 20°C to about 90°C. In another embodiment, the pressing may be carried out at a high temperature of 100°C or higher.

[0206] The positive electrode 10 may be disposed on one surface of the solid electrolyte membrane 30 to which the negative electrode 20 is adhered, and then pressed under a certain pressure, thereby disposing the positive electrode 10 on the surface of the solid electrolyte membrane 30, for example, adhering to the surface of the solid electrolyte membrane 30. In another embodiment, the positive electrodes 10 impregnated with a liquid electrolyte may be stacked without pressing to manufacture a battery.

[0207] The pressing may be, for example, roll pressing, uniaxial pressing, flat pressing, warm isostatic pressing (WIP), or cold isostatic pressing (CIP). However, the present disclosure is not limited to these methods, and any pressing used in the art is possible. The pressure applied during pressing may be, for example, in the range of about 50MPa to about 750MPa. The pressure may be applied for about 5ms to about 60 minutes. The pressing may be carried out at a temperature of, for example, about room temperature to about 90°C or about 20°C to about 90°C. In another embodiment, the pressing may be carried out at a high temperature of 100°C or higher.

[0208] The inventive concept will be described in further detail with reference to the following examples and comparative examples. However, these examples are provided only for illustrative purposes and are not intended to limit the scope of the inventive concept.

[0209] Example

[0210] Preparation of Low Molecular Weight Nonpolar Liquid Rubber

[0211] Preparation Example 1: Preparation of L-BR (1,4-polybutadiene)

[0212] 1,3-Butadiene (21.1 mmol) was mixed with a solution of monomeric neodymium versatate (1.62 mmol), and then diisobutylaluminum hydride (70.1 mmol), triisobutylaluminum (21.5 mmol), and diisobutylaluminum chloride (3.5 mmol) were added thereto to prepare a catalyst. The content of neodymium in the monomeric neodymium versatate was 1.5×10 -4Mole. For the polymerization reaction, nitrogen was fully blown into a 5L glass pressure reactor, and then a cyclohexane polymerization solvent was added in an amount of 6 times the amount of the monomer. The catalyst was transferred and added under nitrogen filling, and then 400g of butadiene as a monomer was added, and the polymerization reaction was carried out at 70°C for 2 hours. After the polymerization reaction, a reaction terminator and an antioxidant were added to terminate the reaction. The remaining solvent was removed from the reaction product by using a rotary evaporator. As a result, L-BR (1,4-polybutadiene) with a weight average molecular weight of 36,000g / mol was obtained.

[0213] Preparation Example 2: Preparation of random copolymer L-SBR (S / B / F226) of styrene, butadiene and farnesene

[0214] 2,200g cyclohexane, 400ppm of ditetrahydrofuranyl propane (DTHFP) as a randomizing agent, 80g styrene, 80g butadiene, and 240g β-farnesene were added to a 5L reactor purged with nitrogen and mixed. The temperature of the reactor was adjusted to 50°C, and n-butyl lithium was then added to initiate the reaction. When the temperature of the reactor reached a peak through an exothermic reaction, the reaction continued for another 10 minutes to allow all monomers to react, and then (triethoxysilylpropyl) diethylamine was added to complete polymerization in an amount of 1.1 molar equivalents relative to the total amount of the monomers. The remaining solvent was removed from the reaction product by using a rotary evaporator. As a result, a styrene / butadiene / farnesene random copolymer (S / B / F 226) containing 20% ​​by weight of styrene, 20% by weight of butadiene, and 60% by weight of farnesene was prepared, with a weight average molecular weight of 20,000g / mol, and represented by Formula 2. At this point, 8 wt% of the copolymer was coupled to form a branched structure having a weight average molecular weight of 43,000 g / mol.

[0215] Formula 2

[0216]

[0217] Wherein, in Formula 2, the mixing weight ratio of repeating units of styrene, butadiene, and farnesene is 2:2:6.

[0218] Preparation of solid electrolyte

[0219] Example 1

[0220] 98 parts by weight of an argyrodite-type sulfide solid electrolyte (Li6PS5Cl), 1.5 parts by weight of a polyacrylate (weight average molecular weight: 500,000 g / mol) as a high molecular weight polymer binder (hereinafter, referred to as a "binder"), 1.5 parts by weight of the liquid butadiene rubber (L-BR) of Preparation Example 1 (which is a low molecular weight liquid rubber as a plasticizer), 0.5 parts by weight of a nonionic dispersant (manufactured by CRODA, Hypermer KD13), and 66.64 parts by weight of octyl acetate as a solvent are added to a container and mixed by using a paste mixer, thereby preparing a composition for forming a solid electrolyte membrane having a solid content of about 60% by weight.

[0221] The liquid butadiene rubber (L-BR) of Preparation Example 1 had a glass transition temperature of -85°C, a weight average molecular weight of 36,000 g / mol, and a viscosity of 50,000 cps.

[0222] The mixing weight ratio of the binder to the low molecular weight nonpolar liquid rubber is 1: 1. In this regard, the binder (polyacrylate) is a terpolymer containing repeating units of ethyl acrylate-butyl acrylate-butyl methacrylate, and the weight ratio thereof is 1:1:1.

[0223] The composition for forming a solid electrolyte membrane was applied to a release film and coated using a doctor blade, followed by primary drying in a convection oven at 80° C. for 30 minutes and vacuum drying in a vacuum oven at 70° C. for 2 hours, thereby forming a solid electrolyte membrane having a thickness of about 100 μm.

[0224] Example 2-3

[0225] A solid electrolyte membrane was manufactured in the same manner as in Example 1, except that the compositions of the binder and the low-molecular-weight nonpolar liquid rubber were changed as shown in Table 1 when preparing the composition for forming a solid electrolyte membrane.

[0226] Comparative Examples 1-3

[0227] A solid electrolyte membrane was manufactured in the same manner as in Example 1, except that in preparing the composition for forming a solid electrolyte membrane, a binder was added in the amount shown in Table 1, and no low molecular weight nonpolar liquid rubber was added.

[0228] Table 1

[0229]

[0230] In Table 1, the amounts of binder and plasticizer are expressed in wt %, and the weight basis is based on the solid electrolyte membrane (solid The total weight of electrolyte + binder + plasticizer + non-ionic dispersant) (excluding solvent).

[0231] Comparative Example 4

[0232] A solid electrolyte membrane was manufactured in the same manner as in Example 3, except that polyethylene glycol (400) (weight average molecular weight: 400 g / mol) was used instead of the low molecular weight nonpolar liquid rubber in preparing the composition for forming a solid electrolyte membrane.

[0233] Comparative Example 5

[0234] The solid electrolyte membrane was manufactured in the same manner as in Example 3, except that dioctyl phthalate (DOP) was used instead of the low molecular weight nonpolar liquid rubber when preparing the composition for forming the solid electrolyte membrane. The mixing weight ratio of the plasticizer (dioctyl phthalate) / binder was 1.

[0235] Table 2

[0236] category Amount of binder (wt%) Amount of plasticizer Plasticizers Example 3 3 3 L-BR Comparative Example 3 3 - - Comparative Example 4 3 3 PEG(400) Comparative Example 5 3 3 DOP(P / B=1)

[0237] In Table 2, P / B represents the weight ratio of plasticizer / binder.

[0238] Example 4

[0239] A solid electrolyte membrane was manufactured in the same manner as in Example 3 except that L-SBR (viscosity: 12,900 cps) of Preparation Example 2 was used as the low molecular weight nonpolar liquid rubber in preparing the composition for forming a solid electrolyte membrane.

[0240] Example 5

[0241] A solid electrolyte membrane was manufactured in the same manner as in Example 4, except that the mixing weight ratio (P / B) of the plasticizer to the binder was changed to 0.5 when preparing the composition for forming a solid electrolyte membrane.

[0242] Table 3

[0243] category Amount of binder (wt%) Amount of plasticizer (%) Plasticizers Example 3 3 3 L-BR(P / B=1) Example 4 3 3 L-SBR (P / B=1) Example 5 3 1.5 L-SBR (P / B = 0.5) Comparative Example 3 3 - - Comparative Example 5 3 3 DOP

[0244] Fabrication of all-solid-state secondary batteries

[0245] Example 6

[0246] positive electrode

[0247] Preparation of LiNi 0.8 Co 0.15 Al 0.05 O2(NCA)(D 50 =14 μm) as the positive electrode active material.

[0248] A crystalline argyrodite-type solid electrolyte (Li6PS5Cl) powder is prepared as a solid electrolyte. Carbon nanofibers (CNF) are prepared as a conductive agent, and polyvinylidene fluoride (PVDF) is prepared as a binder. The positive electrode active material, solid electrolyte, conductive agent, and binder are mixed in a weight ratio of 84:14.8:0.2:1.0, and then mixed with octyl acetate as a solvent to prepare a slurry, and then the slurry is applied to a positive electrode current collector made of 18μm thick carbon-coated aluminum foil to prepare a positive electrode. The positive electrode active material layer has a thickness of about 100μm (positive electrode 4mAh / cm 2 L / L).

[0249] negative electrode

[0250] As the negative electrode, a carbon-silver (AgC) negative electrode manufactured according to the following process was used.

[0251] A carbon-silver (AgC) negative electrode was prepared by forming a negative electrode active material layer containing a composite (AgC) including a carbon-based active material and Ag with a thickness of 10 μm on a stainless steel substrate with a thickness of 10 μm.

[0252] For the negative electrode active material layer, the following powder was prepared: carbon black (CB) having an average particle diameter of about 38 nm as a carbon-based material and Ag particles having an average particle diameter of about 60 nm were mixed in a weight ratio of 3:1. 4 g of the mixed powder and 6 g of an NMP solution including 5 wt % PVDF binder were mixed, and NMP was added little by little while stirring to prepare a negative electrode active material layer slurry. The negative electrode active material layer slurry was applied to a stainless steel substrate by using a blade coater and dried at 80° C. in an air atmosphere for 20 minutes. Subsequently, the dried resultant was vacuum dried at 100° C. for 12 hours to thereby complete the manufacture of the negative electrode.

[0253] Solid electrolyte membrane

[0254] A laminate was prepared by placing the solid electrolyte membrane (1SE) manufactured according to Comparative Example 1 on the positive electrode. The prepared laminate was subjected to warm isostatic pressing at 85° C. and a pressure of 500 MPa for 30 minutes as a first pressing process to manufacture a positive electrode / 1SE structure. After pressing, the 1SE had a thickness of about 50 μm.

[0255] The positive electrode / 1SE structure, the solid electrolyte membrane (2SE) manufactured according to Example 4 (thickness: about 100 μm before pressing), and the negative electrode were sequentially arranged to prepare a stack, and the stack was subjected to WIP at 85°C and a pressure of 200 MPa for 30 minutes as a second pressing process to manufacture a positive electrode / 1SE / 2SE / negative electrode structure, thereby completing the manufacture of an all-solid-state secondary battery.

[0256] Example 7

[0257] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the solid electrolyte membrane manufactured according to Example 3 was used instead of the solid electrolyte membrane manufactured according to Example 4.

[0258] Comparative Example 6

[0259] An all-solid-state secondary battery was manufactured in the same manner as in Example 6, except that the solid electrolyte membrane of Comparative Example 3 was used as 2SE.

[0260] Evaluation Example 1: Ionic Conductivity

[0261] As a solid electrolyte membrane sample, the solid electrolyte membrane of Examples 1 and 3, or the second solid electrolyte membrane (2SE) obtained according to Example 4 used in the all-solid-state secondary battery of Example 6 was prepared. Ten sheets of each solid electrolyte membrane sample were stacked and then pressed with a pressure of 4 tons to thereby manufacture an indium blocking battery (cell) to manufacture a sample for measuring ionic conductivity. A symmetric battery was manufactured as follows: indium (In) electrodes having a thickness of 50 μm and a diameter of 13 mm were placed on both surfaces of the sample, respectively. The impedance of the solid electrolyte membrane was measured by a 2-probe method at 25°C using an impedance analyzer. The frequency range was set to 0.1 Hz to 1 MHz, and the amplitude voltage was set to 10 mV. The resistance value was calculated from the arc of the Nyquist diagram, and then the ionic conductivity was calculated considering the area and thickness of the sample.

[0262] As a result, it was confirmed that the solid electrolyte membranes of Examples 1, 3, and 4 had excellent ion conductivities, namely, 0.45 mS / cm, 0.36 mS / cm, and 0.45 mS / cm, respectively.

[0263] Evaluation Example 2: Evaluation of strain rate and Young's modulus

[0264] The strain rate of each of the solid electrolyte membranes of Examples 1 to 3 and Comparative Examples 1 to 5 having a width of 12 mm and a length of 30 mm was evaluated using the ratio of the bending length to the span width (14 mm), and the evaluation results are shown in Tables 4 and 5. The stress changes in the solid electrolyte membranes of Example 3 and Comparative Example 3 according to the strain rate from the preload are shown in Tables 4 and 5. Figure 1 Young's modulus is called flexural or bending modulus and is measured by DMA800 (TAInstruments), a solid electrolyte membrane specimen is prepared by ASTM standard D412 (V-type specimen), the change of strain against stress of the specimen is measured at 25°C, a relative humidity of about 30%, and a rate of 5 mm / min, and Young's modulus (tensile modulus) is obtained from the slope of the stress-strain curve.

[0265] Table 4

[0266]

[0267] Referring to Table 4, it can be confirmed that as the amount of binder in each of the solid electrolyte membranes of Examples 1 to 3 increases, the effect of adding a low molecular weight non-polar liquid rubber as a plasticizer increases, and the solid electrolyte membranes of Examples 1 to 3 have an increased strain rate compared to Comparative Example 1 and a decreased Young's modulus compared to Comparative Examples 1 to 3, resulting in improved flexibility.

[0268] Young's modulus is a parameter indicating ductility, and in Comparative Examples 1 to 3, Young's modulus is maintained even when the amount of the binder is increased. Thus, the solid electrolyte membranes of Comparative Examples 1 to 3 do not show a change in ductility.

[0269] In contrast, it can be confirmed that the solid electrolyte membranes of Examples 1 to 3 have increased ductility due to reduced Young's modulus compared to Comparative Examples 1 to 3.

[0270] refer to Figure 1 It can also be confirmed that, compared with the solid electrolyte membrane of Comparative Example 3 which does not include a plasticizer, the solid electrolyte membrane of Example 3 which includes a low molecular weight nonpolar liquid rubber as a plasticizer has a flexibility improvement effect due to the use of the low molecular weight nonpolar liquid rubber.

[0271] Table 5

[0272]

[0273] Referring to Table 5, the solid electrolyte membrane of Example 3 exhibits a high strain rate compared to the solid electrolyte membranes of Comparative Examples 3-5.

[0274] In the solid electrolyte membrane of Comparative Example 4, PEG400 is used as a plasticizer, and the conductivity of the solid electrolyte membrane is greatly reduced to 0.25 mS / cm due to the polar ether group in the PEG chain. When the organic monomer type DOP is applied, the solid electrolyte membrane of Comparative Example 5 has poor mechanical properties and low reproducibility due to evaporation problems, side reactions, etc. during the drying / pressing process during the solid electrolyte membrane formation process.

[0275] The strain rates of the solid electrolyte membranes of Examples 4 and 5 and Comparative Example 3 were evaluated, and the results are shown in Table 6, and some of the evaluation results are shown in Table 6. Figure 2 In this regard, the solid electrolyte membrane was formed to a thickness of 85 μm. The stress changes according to strain in the solid electrolyte membranes of Examples 4 and 5 and Comparative Example 3 are shown in Figure 2 middle.

[0276] Table 6

[0277]

[0278] Referring to Table 6, the solid electrolyte membranes of Examples 4 and 5 exhibited improved strain rates compared to the solid electrolyte membrane of Comparative Example 3. Figure 2 As shown in , it was confirmed that the solid electrolyte membranes of Examples 4 and 5 exhibited a flexibility improvement effect compared to the solid electrolyte membrane of Comparative Example 3 due to an increased strain rate when an increased amount of the plasticizer was used.

[0279] Evaluation Example 4: Rate Characteristics

[0280] The all-solid-state secondary batteries manufactured according to Examples 6 and 7 and Comparative Example 6 were placed in a chamber at 45°C. Each all-solid-state secondary battery was charged at a constant current of 0.1C rate until the voltage reached 4.25V (relative to Li), and then cut off at a current of 0.05C rate while maintaining a constant voltage of 4.25V. Each all-solid-state secondary battery was discharged once at a constant current of 0.1C, 0.33C, or 1.0C until the voltage reached 2.5V (relative to Li), and its discharge capacity according to the C rate was measured, and the results are shown in Table 7.

[0281] Table 7

[0282]

[0283]

[0284] Referring to Table 7, the all-solid-state secondary battery of Example 6 uses the second solid electrolyte of Example 4, and has excellent flexibility compared to the all-solid-state secondary battery of Comparative Example 6, and when a solid electrolyte membrane including a low molecular weight rubber plasticizer is used, an excellent bonding interface is formed even under low pressing conditions compared to the comparative example, resulting in improved battery characteristics. As a result, it is confirmed that the all-solid-state secondary battery of Example 6 has further improved discharge capacity and resistance characteristics in terms of high rate performance at 1C compared to the all-solid-state secondary battery of Comparative Example 6.

[0285] Similar to the all-solid-state secondary battery of Example 6, the all-solid-state secondary battery of Example 7 exhibits further improved discharge capacity and resistance characteristics in terms of high-rate performance at 1C compared to the all-solid-state secondary battery of Comparative Example 6.

[0286] Evaluation Example 5: Is the battery operational?

[0287] It was evaluated whether the all-solid-state secondary batteries of Example 6 and Comparative Example 6 operated when charged at 0.33C.

[0288] Whether each battery operates or not is determined by the presence or absence of a micro short circuit by a charging and discharging method at a constant current which will be described below.

[0289] The all-solid-state secondary batteries manufactured according to Example 6 and Comparative Example 6 were placed in a chamber at 45° C. Each all-solid-state secondary battery was charged at a constant current of 0.33C rate until the voltage reached 4.25V (relative to Li), and then cut off at a current of 0.05C rate while maintaining a constant voltage of 4.25V.

[0290] Each all-solid-state secondary battery was discharged once at a constant current of 0.33C rate until the voltage reached 2.5 V (vs. Li).

[0291] The results of the occurrence of short circuits in each all-solid-state secondary battery when charged at 0.33C are shown in Tables 8 and Figure 3 middle.

[0292] Table 8

[0293] category Is it chargeable at 0.33C? Example 6 Rechargeable Comparative Example 6 Micro short circuit (overcharge)

[0294] As shown in Table 8 and Figure 3 As shown in , unlike the all-solid-state secondary battery of Comparative Example 6, the all-solid-state secondary battery of Example 6 is suitable for formation of a bonding interface between electrode plates even under a low bonding pressure, and therefore operates well even when charged at 0.33C.

[0295] Although the embodiments have been described with reference to the accompanying drawings and examples, these are provided for illustrative purposes, and those skilled in the art will appreciate that various modifications and other equivalent embodiments may be made therefrom. Therefore, the scope of the present application should be defined by the appended claims.

[0296] The solid electrolyte membrane according to the embodiment has improved flexibility without reducing ion conductivity. When the solid electrolyte membrane is used, the pressing process conditions can be relaxed and microcracks and breakage can be suppressed, thereby enabling the manufacture of an all-solid-state secondary battery with improved stability.

[0297] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for limiting purposes. The description of features or aspects in each embodiment should typically be considered to be applicable to other similar features or aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope as defined by the appended claims.

Claims

1. Solid electrolyte membrane, comprising: Solid electrolytes; a high molecular weight polymer binder having a weight average molecular weight greater than 75,000 grams / mole (g / mol) but less than or equal to 1,000,000 g / mol; and Low molecular weight non-polar liquid rubber, The low molecular weight non-polar liquid rubber has a weight average molecular weight of 2,000 g / mol to 75,000 g / mol and a viscosity of 1 centipoise (cps) to 100,000 cps. 2 . The solid electrolyte membrane according to claim 1 , wherein the low molecular weight nonpolar liquid rubber has a glass transition temperature of −95° C. to −6° C.

3. The solid electrolyte membrane according to claim 1, wherein the amount of the low molecular weight nonpolar liquid rubber is 5 wt% or less with respect to the total weight of the solid electrolyte membrane. 4 . The solid electrolyte membrane of claim 1 , wherein the low molecular weight nonpolar liquid rubber has a weight average molecular weight of 5,000 to 45,000 g / mol.

5. The solid electrolyte membrane according to claim 1, wherein the low molecular weight nonpolar liquid rubber is a homopolymer containing a unit structure derived from a conjugated diene monomer, or The low molecular weight nonpolar liquid rubber is a copolymer containing a unit structure derived from a conjugated diene first monomer and an aromatic vinyl second monomer.

6. The solid electrolyte membrane according to claim 1, wherein the low molecular weight nonpolar liquid rubber is a terpolymer having a unit structure derived from a conjugated diene first monomer, an aromatic vinyl second monomer, and a conjugated polyene third monomer.

7. A solid electrolyte membrane as described in claim 1, wherein the low molecular weight non-polar liquid rubber comprises liquid butadiene rubber, liquid isoprene rubber, liquid styrene butadiene rubber, liquid natural rubber, liquid acrylonitrile-butadiene rubber, liquid isobutylene-isoprene rubber, liquid isoprene propylene rubber, liquid styrene-butadiene-farnesene copolymer, a copolymer in which a farnesene block is formed at the end of a styrene-butadiene random copolymer, a copolymer in which a butadiene block is formed at the end of a styrene-farnesene random copolymer, or a combination thereof.

8. The solid electrolyte membrane of claim 1, wherein the high molecular weight polymer binder has a weight average molecular weight of 100,000 g / mol to 1,000,000 g / mol, and The high molecular weight polymer binder includes polyacrylate, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, hydrogenated nitrile rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester, nylon, a copolymer including a unit structure derived from a non-polar monomer and at least one polar monomer selected from a nitrile-based monomer and a (meth)acrylic monomer, an ethylene vinyl acetate copolymer, or a combination thereof.

9. The solid electrolyte membrane of claim 1, wherein the solid electrolyte comprises a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, a gel electrolyte, or a combination thereof, The gel electrolyte comprises a polymer gel electrolyte.

10. The solid electrolyte membrane according to claim 1, wherein the solid electrolyte has a crystalline structure. 11 . The solid electrolyte membrane according to claim 10 , wherein the solid electrolyte comprises the sulfide solid electrolyte, and the sulfide solid electrolyte is an argyrodite type compound.

12. The solid electrolyte membrane according to claim 1, wherein the solid electrolyte membrane has a strain rate of 0.095% or more, and The solid electrolyte membrane has a Young's modulus of 10 GPa to 20 GPa.

13. All-solid-state secondary battery, including: A positive electrode, a negative electrode current collector, and a solid electrolyte layer disposed between the positive electrode and the negative electrode current collector, The solid electrolyte layer comprises the solid electrolyte membrane according to any one of claims 1 to 12.

14. The all-solid-state secondary battery according to claim 13, wherein the positive electrode comprises a positive electrode current collector, wherein at least one of the positive electrode current collector or the negative electrode current collector comprises a base film and a metal layer disposed on one side or both sides of the base film, wherein the base film comprises a polymer, and the polymer comprises polyethylene terephthalate, polyethylene, polypropylene, polybutylene terephthalate, polyimide, or a combination thereof, and The metal layer includes indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, lithium, or alloys thereof.

15. The all-solid-state secondary battery according to claim 13, wherein a first negative electrode active material layer is disposed between the negative electrode current collector and the solid electrolyte layer, wherein the first negative electrode active material layer comprises a negative electrode active material and a binder, the negative electrode active material comprises at least one of a carbon-based negative electrode active material or a metal or metalloid negative electrode active material, and The carbon-based negative electrode active material includes amorphous carbon, crystalline carbon, porous carbon, or a combination thereof.

16. The all-solid-state secondary battery according to claim 15, further comprising, after the all-solid-state secondary battery is charged, a second negative electrode active material layer disposed between the negative electrode current collector and the first negative electrode active material layer, The second negative electrode active material layer is a metal layer, and the metal layer includes lithium or a lithium alloy.

17. All-solid-state secondary battery, including: A positive electrode, a negative electrode current collector, and a solid electrolyte layer disposed between the negative electrode current collector and the positive electrode, wherein the solid electrolyte layer comprises a first solid electrolyte layer and a second solid electrolyte layer, wherein the first solid electrolyte layer is in contact with the positive electrode, The second solid electrolyte layer is in contact with the negative electrode, and At least one of the first solid electrolyte layer or the second solid electrolyte layer includes the solid electrolyte membrane according to any one of claims 1 to 12. 18 . The all-solid-state secondary battery according to claim 17 , wherein the second solid electrolyte layer is the solid electrolyte membrane.

19. A method for manufacturing a solid electrolyte membrane, the method comprising: preparing a composition for forming a solid electrolyte membrane, the composition comprising a solid electrolyte, a high molecular weight polymer binder, a low molecular weight nonpolar liquid rubber, and a solvent; as well as coating a substrate with the composition to form a coated substrate; and drying the coated substrate to produce the solid electrolyte membrane according to any one of claims 1 to 12 on the substrate.

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