Solid electrolyte for all-solid-state battery and all-solid-state battery comprising same

Abstract

Disclosed are a solid electrolyte for an all-solid-state battery, which can resist moisture by chemically reacting with a sulfide-containing solid electrolyte with an amphiphilic compound (e.g., a surfactant material), and a solid-state battery comprising the same. The solid electrolyte for an all-solid-state battery has been surface-modified with an amphiphilic compound having a hydrophilic group and a hydrophobic group.

Description

Technical Field

[0001] This application claims the priority benefit of U.S. Patent Application No. 18 / 428,312, filed January 31, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a sulfide-containing solid electrolyte that has advantages in ionic conductivity and thermal stability compared to liquid electrolytes or polymer / oxide-based solid electrolytes; more specifically, it relates to a solid electrolyte for all-solid-state batteries that is immune to moisture by introducing a surfactant-concept material into the sulfide-containing solid electrolyte through a chemical reaction; and an all-solid-state battery comprising the solid electrolyte. Background Technology

[0003] Electrification of transportation continues to grow, exemplified by the widespread adoption of electric vehicles (EVs) and the emergence of urban air mobility (UAM) vehicles. Simultaneously, the demand for stationary energy storage systems powered by solar and wind turbines is increasing, particularly in the residential and industrial sectors. This shift is partly driven by the urgent need to mitigate the adverse environmental and climate impacts associated with traditional internal combustion engines and other non-renewable power generation methods. Therefore, developing battery technologies with high energy density while ensuring enhanced safety has become a top priority.

[0004] Considering the limitations of batteries in terms of capacity, safety, output, size, and miniaturization, various batteries that can overcome these limitations of lithium secondary batteries are currently being researched.

[0005] Ongoing research focuses on different types of batteries. These include metal-air batteries with large theoretical capacities and all-solid-state batteries that pose no risk of explosion. Other areas include supercapacitors for output, large-size NaS batteries or redox flow batteries (RFB), and miniaturized thin-film batteries.

[0006] Solid-state batteries, also known as all-solid-state batteries, replace the liquid electrolyte used in existing lithium-ion batteries with a solid electrolyte. These batteries are safer because they do not use flammable solvents, eliminating the possibility of fire or explosion due to the decomposition of conventional electrolytes. Solid-state batteries particularly offer advantages over liquid electrolytes in lithium-ion batteries (LIBs), which suffer from low stability, low energy density, and short lifespan. Furthermore, because solid-state batteries can use lithium metal or lithium alloys as the negative electrode material, they can significantly improve battery energy density.

[0007] Meanwhile, the solid electrolytes in this all-solid-state battery can be broadly categorized into organic (polymer-containing) solid electrolytes and inorganic solid electrolytes. Inorganic solid electrolytes can be further divided into sulfide-containing and oxide-containing solid electrolytes. Furthermore, the solid electrolyte under key technological development is the sulfide-containing solid electrolyte, with a focus on achieving ionic conductivity levels approaching those of organic electrolyte solutions. Thus, because sulfide-containing solid electrolytes not only possess 10... -3 S / cm to 10 -2 With a high ionic conductivity of S / cm and excellent thermal stability and ductility, it can improve resistance through good contact with the interface (interface compatibility).

[0008] However, because sulfide-containing solid electrolytes are sensitive to moisture, for example, they produce toxic gases belonging to the H2S (hydrogen sulfide) family when in contact with water, a very dry environment must be constructed when manufacturing batteries or electrodes. This invention aims to provide specific and practical solutions to these problems. Summary of the Invention

[0009] [Technical Issues]

[0010] Therefore, the object of the present invention is to provide a solid electrolyte for an all-solid-state battery and an all-solid-state battery containing the solid electrolyte, wherein the solid electrolyte is protected from moisture by chemically reacting a surfactant-concept material with the sulfide-containing solid electrolyte and thereby introducing it.

[0011] [Technical Solution]

[0012] To achieve the above objectives, the present invention provides a solid electrolyte for all-solid-state batteries, which is surface-modified with an amphiphilic compound having both hydrophilic and hydrophobic groups.

[0013] Furthermore, the present invention provides an all-solid-state battery comprising: a positive electrode; a negative electrode; and a solid electrolyte for all-solid-state batteries as described herein.

[0014] [Beneficial Effects]

[0015] The advantages of the solid electrolyte for all-solid-state batteries and the all-solid-state battery containing the solid electrolyte of the present invention are that the solid electrolyte containing sulfides is protected from the influence of moisture by chemically reacting a material of the surfactant concept with the sulfide-containing solid electrolyte and thereby introducing it. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the structure of an amphiphilic compound contained in a solid electrolyte for an all-solid-state battery, according to one aspect of the present invention. Figure 1(a) is a diagram showing the division of amphiphilic compounds into hydrophilic and hydrophobic sites. Figure 1 (b) is a diagram of an exemplary amphiphilic compound.

[0017] Figure 2 The image shows the difference in structural stability between the solid electrolyte of the present invention and conventional solid electrolytes, depending on the degree of moisture exposure.

[0018] Figure 3 The image shows the differences in structural stability of conventional solid electrolytes depending on the degree of moisture exposure (exposure to air).

[0019] Figure 4 This is a graph showing the difference in ionic conductivity between the solid electrolyte of the present invention and conventional solid electrolytes, depending on the degree of moisture exposure (exposure to air).

[0020] Figure 5 This is a graph showing the difference in ionic conductivity between the solid electrolyte of the present invention and conventional solid electrolytes, depending on the degree of moisture exposure (exposure to air).

[0021] Figure 6 This is a graph showing the differences in ionic conductivity of conventional solid electrolytes depending on the degree of moisture exposure (exposure to air). Detailed Implementation

[0022] The present invention will now be described in detail.

[0023] The solid electrolyte for all-solid-state batteries of the present invention is characterized in that it is surface modified with an amphiphilic compound having hydrophilic and hydrophobic groups. Specifically, the surface modification is performed with an amphiphilic compound in which the hydrophilic group is located on one side and the hydrophobic group is located on the other side and the hydrophilic group is bonded together.

[0024] One aspect of the present invention relates to a solid electrolyte for an all-solid-state battery, comprising a solid electrolyte and a modified layer located on the surface of the solid electrolyte, the modified layer comprising an amphiphilic compound, wherein the amphiphilic compound comprises at least one hydrophilic group and at least one hydrophobic group.

[0025] In another aspect of the invention, the solid electrolyte comprises a sulfide-containing solid electrolyte. In yet another aspect, the solid electrolyte comprises bonds between the hydrophilic groups of an amphiphilic compound and the surface of the sulfide-containing solid electrolyte.

[0026] In another aspect of the invention, the hydrophilic group of the amphiphilic compound is at least one selected from the group consisting of thiol group, amino group, isocyanate group and ethoxysilyl group.

[0027] In another aspect of the invention, the hydrophobic group of the amphiphilic compound is a hydrocarbon group substituted with a fluorinated or organosilicon compound.

[0028] In another aspect of the invention, the amphiphilic compound is a compound containing a perfluorothiol. In another aspect, the compound containing a perfluorothiol is a C1-C30 aliphatic or aromatic hydrocarbon substituted with 1 to 20 fluorine groups and 1 to 5 thiol groups.

[0029] In one aspect of the invention, the perfluorothiol-containing compound is a C8-C12 hydrocarbon substituted with 15 to 20 fluorine groups and 1 to 3 thiol groups.

[0030] On the other hand, compounds containing perfluorothiols are C10 hydrocarbons substituted with 17 fluorine groups and 1 thiol group. For example, a compound containing a perfluorothiol is CF3(CF2)7(CH2)2SH. This structure is known to be registered under CAS number 34143-74-3 (1H,1H,2H,2H-perfluorodecylthiol).

[0031] In one aspect of the invention, the sulfide-containing solid electrolyte includes Li6PS5Cl.

[0032] In another aspect of the invention, based on 100% by weight of a solid electrolyte for all-solid-state batteries, the content of the amphiphilic compound is from 5% by weight to 30% by weight.

[0033] In another aspect of the invention, the thickness of the modified layer containing the amphiphilic compound is from 0.1 μm to 3 μm. In other aspects, the thickness is from 0.1 μm to 1 μm, or from 0.3 μm to 0.5 μm.

[0034] On the other hand, the hydrophilic groups of the perfluorothiol-containing compound are bonded to the solid electrolyte, and the hydrophobic groups of the perfluorothiol-containing compound are located on the outermost side of the solid electrolyte.

[0035] In one aspect of the invention, the invention relates to an all-solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte disclosed herein.

[0036] In one aspect of the invention, the solid electrolyte is positioned as a layered membrane located between the positive and negative electrodes. Alternatively or supplementally, the solid electrolyte is mixed and contained in the positive electrode active material and / or the negative electrode active material.

[0037] In another aspect of the invention, the all-solid-state battery may be a semi-solid-state battery that further includes a liquid electrolyte.

[0038] solid electrolyte

[0039] The solid electrolyte for all-solid-state batteries of the present invention can contain a sulfide-containing solid electrolyte as a parent material. Furthermore, the solid electrolyte for all-solid-state batteries of the present invention is characterized in that the surface of the parent material is modified with an amphiphilic compound having a hydrophilic group on one side and a hydrophobic group on the other side, and the hydrophilic group of the amphiphilic compound is bonded to the surface of the parent material. In other words, the solid electrolyte for all-solid-state batteries is characterized in that it can include a sulfide-containing solid electrolyte as a parent material, and the surface of the parent material is modified with an amphiphilic compound.

[0040] The parent material, such as a sulfide-containing solid electrolyte, may contain a lithium salt, and the lithium salt may be derived from Li. + X - This indicates that it is an ionizable lithium salt. The anion of lithium salts is not particularly limited; for example, F... - Cl - ,Br - I - NO3 - N(CN)2 - BF4 - ClO4 - PF6 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - CF3SO3 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - etc. For the purposes of this invention, any suitable sulfide-containing electrolyte material can be used. As used herein, "sulfide-containing electrolyte" refers to an electrolyte containing conductive ions (e.g., Li₂). +An electrolyte containing sulfur-containing inorganic materials, suitable for electrically insulating the positive and negative electrodes of an electrochemical cell. An exemplary sulfide-containing electrolyte is described in Shaojie Chen et al.'s "..." Sulfide solid electrolytes for all-solid-state lithium batteries: Structure, conductivity, stability and application “ Energy Storage Materials As described in Volume 14, pp. 58-74 (September 2018), the entire text is explicitly incorporated into this paper by reference.

[0041] For example, many sulfide-containing electrolyte materials have high superionic conductivity (up to ~10). -2 Scm -1 Its deformability is particularly attractive. In particular, Li3P7S has been reported to... 11 Li 10 GeP2S 12 Furthermore, Na3PS4 and Li6PS5Cl exhibit high ionic conductivity; some even approach the ionic conductivity of liquid electrolytes. According to aspects of the invention, sulfide solid electrolyte materials also provide a low Young's modulus, which facilitates good interfacial contact with electrode materials through simple cold pressing at room temperature.

[0042] The sulfide-containing solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group I or Group II of the periodic table, and may include Li-PS-based glass, Li-PS-based glass ceramics and sulfide-containing solid electrolytes of silver-germanium ore type. Non-limiting examples of such sulfide-containing solid electrolytes include one or more of Li₂S-P₂S₅, Li₂S-LiI-P₂S₅, Li₂S-LiI-Li₂O-P₂S₅, Li₂S-LiBr-P₂S₅, Li₂S-LiCl-P₂S₅, Li₂S-Li₂O-P₂S₅, Li₂S-Li₃PO₄-P₂S₅, Li₂S-P₂S₅-P₂O₅, Li₂S-P₂S₅-SiS₂, Li₂S-P₂S₅-SnS, Li₂S-P₂S₅-Al₂S₃, Li₂S-GeS₂, Li₂S-GeS₂-ZnS, or Li₆PS₅X (X = at least one of Cl, Br, or I). Furthermore, the sulfide-containing solid electrolytes included as the parent material in the all-solid-state battery solid electrolyte of the present invention are not limited thereto, and can be composed of any known sulfide-containing solid electrolyte.

[0043] The parent material of the solid electrolyte for the all-solid-state battery of the present invention, i.e., the sulfide-containing solid electrolyte, preferably contains LPSCl (lithium sulfophosphate chloride) compounds, and more preferably contains Li6PS5Cl, which is preferred from the perspective of its function as a transport layer for ion movement via redox reactions. Furthermore, the parent material of the solid electrolyte for the all-solid-state battery of the present invention, i.e., the sulfide-containing solid electrolyte, can more preferably be composed of Li6PS5Cl.

[0044] The amphiphilic compound located on the surface of the parent material has a hydrophilic group on one side and a hydrophobic group on the other side, and the hydrophilic group of the amphiphilic compound is bonded to the surface of the parent material (e.g., an S-S bond is formed due to the strong E-bonding between the S group of Li6PS5Cl and the S group of the thiol group of the amphiphilic compound). In other words, the hydrophilic group of the amphiphilic compound acts as a linker between the parent material and the hydrophobic group of the amphiphilic compound. Therefore, the hydrophobic group of the amphiphilic compound does not contact the parent material. Furthermore, the solid electrolyte comprises the bond between the hydrophilic group of the amphiphilic compound and the surface of the sulfide-containing solid electrolyte.

[0045] In amphiphilic compounds, the hydrophilic group can be selected from thiol groups, amino groups, isocyanate groups, and suitable leaving groups, such as ethoxysilyl (e.g., triethoxysilyl or trimethoxysilyl), but is not limited thereto. However, the most preferred hydrophilic group in amphiphilic compounds is a thiol group that can form an SS bond with a sulfur-containing solid electrolyte (parent material). Therefore, other hydrophilic groups containing sulfur atoms can also be used as the hydrophilic group in amphiphilic compounds, but even in this case, the thiol group is the most preferred.

[0046] The term "thiol" can be understood as an organosulfur compound in the form of R-SH, where R represents an alkyl or other organic substituent. The term "isocyanate" can be understood as having a functional group with the formula RN=C=O, where R can be alkyl or aryl.

[0047] The term "amine" can be understood as a compound or functional group containing a basic nitrogen atom with a lone pair of electrons. Amines are formally derivatives of ammonia (NH3), in which one or more hydrogen atoms have been replaced by substituents such as alkyl or aryl groups (e.g., alkylamines and arylamines). The substituent -NH2 is called an amino group. In some respects, amines can include primary, secondary, and / or tertiary amines. In some respects, the amino group can be further converted into a useful leaving group, for example, by conversion to ammonium salts, aryl (sulfonyl)amino groups, etc.

[0048] Furthermore, the hydrophobic group in the amphiphilic compound is a hydrocarbon group that has substituted a fluorinated or organosilicon compound (e.g., silane, alkoxysilane, isocyanate). Here, the hydrophilic group is in a state where substitution occurs at the carbon atom contained in the hydrophobic group. According to aspects of the invention, the total number of carbons (including chains and substituents) is 6 to 16 carbons, or according to some aspects of the invention, 6 to 12 carbons, 8 to 12 carbons, or 10 to 12 carbons. The hydrocarbon group may have a total of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbons.

[0049] For example, the hydrocarbon group can be a substituted or unsubstituted C3-C20 alkyl group, including but not limited to substituted or unsubstituted n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, isopentyl, n-hexyl, isohexyl, sec-hexyl, tert-hexyl, n-heptyl, isohexyl, sec-heptyl, tert-heptyl, n-octyl, isooctyl, sec-octyl, tert-octyl, n-nonyl, isononyl, sec-nonyl, tert-nonyl, n-decyl, isodel, sec-decyl, tert-decyl, n-undecyl, isoundecyl, sec-undecyl, tert-undecyl, n-dodecyl, isododecyl, sec-dodecyl, tert-dodecyl, etc.

[0050] Hydrophilic and hydrophobic groups are located separately in a compound, thus forming hydrophilic and hydrophobic sites respectively. Figure 1 This is a diagram illustrating the structure of an amphiphilic compound contained in a solid electrolyte for an all-solid-state battery, according to one aspect of the present invention. Figure 1 (a) is a diagram showing the division of amphiphilic compounds into hydrophilic and hydrophobic sites. Figure 1 (b) is its more specific diagram.

[0051] As an example of the bonding relationship between the aforementioned parent material and the amphiphilic compound, in one aspect, the hydrophilic thiol group and the hydrophobic fluorinated hydrocarbon group can be sequentially connected from the surface of the parent material (e.g., LPSCl type compounds) outwards. However, as mentioned above, this is not the only limitation. Furthermore, Figure 1 The amphiphilic compound shown in (b) is a compound containing perfluorothiol. Various compounds containing perfluorothiol can be cited as amphiphilic compounds of the present invention.

[0052] More specifically, in one aspect of the invention, the perfluorothiol-containing compound may be an aliphatic or aromatic hydrocarbon of C1 to C30, preferably C3 to C20, more preferably C7 to C15, substituted with 1 to 20, preferably 5 to 20, more preferably 8 to 18 fluorine groups and 1 to 5, preferably 1 to 3 thiol groups. In this aspect of the invention, any fluorine substitution in the range of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 may be present. In this aspect of the invention, any thiol group in the range of 1, 2, 3, 4, and 5 may be present.

[0053] Relative to 100% by weight of the solid electrolyte for all-solid-state batteries of the present invention, the content of the amphiphilic compound located on the surface of the parent material can be 5 to 30% by weight, preferably 10 to 20% by weight, more preferably 13 to 18% by weight. In aspects of the present invention, based on 100% by weight of the solid electrolyte for all-solid-state batteries of the present invention, the content of the amphiphilic compound located on the surface of the parent material can be taken from any range of weights from data points 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30. Based on 100% by weight of the solid electrolyte for all-solid-state batteries of the present invention, if the content of the amphiphilic compound is less than 5% by weight, it may be difficult to protect the sulfide-containing solid electrolyte from the influence of moisture. Furthermore, based on 100% by weight of the solid electrolyte for all-solid-state batteries of the present invention, if the content of the amphiphilic compound exceeds 30% by weight, there may be a problem of a significant decrease in the ionic conductivity of the sulfide-containing solid electrolyte.

[0054] Furthermore, the thickness of the amphiphilic compound layer (or the modified layer containing the amphiphilic compound) located on the surface of the parent material can be from 0.1 μm to 3 μm, preferably from 0.1 μm to 1 μm, and more preferably from 0.3 μm to 0.5 μm. In this invention, the thickness of the amphiphilic compound layer can be in μm within any range of data points 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, and 3.0. If the thickness of the amphiphilic compound layer is less than 0.1 μm, the protective effect against moisture may be degraded because it typically does not function as a moisture-protecting layer. Furthermore, if the thickness of the amphiphilic compound layer exceeds 3 μm, the ionic conductivity of the sulfide-containing solid electrolyte may be greatly reduced, because the amphiphilic compound layer may interfere with lithium-ion transport.

[0055] Because the solid electrolyte used in the aforementioned all-solid-state battery has a hydrophobic outer surface, it can protect the parent material (sulfide-containing solid electrolyte) from moisture. That is, this invention is significant because by introducing a surfactant-based material onto the surface of the parent material, it not only provides moisture protection but also maximizes the effectiveness of moisture protection by increasing hydrophobicity.

[0056] All-solid-state batteries

[0057] The following describes the all-solid-state battery (including a solid electrolyte for all-solid-state batteries) of the present invention. The all-solid-state battery includes a positive electrode, a negative electrode, and the solid electrolyte for all-solid-state batteries described herein.

[0058] Solid electrolytes can be provided without adversely affecting battery performance, for example, independently positioned without mixing with the electrodes (i.e., positioned as a layered membrane between the positive and negative electrodes), mixed with and positioned with any one or more of the positive and negative active materials, or positioned in both.

[0059] This solid electrolyte can function similarly to the separator in a typical lithium-ion secondary battery (i.e., electrically insulate the positive and negative electrodes while allowing lithium ions to pass through). Alternatively, depending on the requirements, all-solid-state batteries can also be used as semi-solid-state batteries that also contain a liquid electrolyte; in this case, a separate polymer separator may be necessary. Conventional liquid electrolytes can be selected.

[0060] The positive electrode includes a positive electrode active material layer, which comprises active materials in the form of particles, conductive materials, and a binder. Additionally, if desired, the positive electrode includes a current collector, and the positive electrode active material layer may be located on at least one surface of the current collector.

[0061] As the positive electrode active material, any material suitable for use as a positive electrode active material in conventional lithium-ion secondary batteries can be used without restriction. Furthermore, the positive electrode active material can be a lithium transition metal oxide containing one or more transition metals. For example, the positive electrode active material can be selected from LiCoO2, LiNiO2, LiMnO2, Li2MnO3, LiMn2O4, Li(Ni) a Co b Mn c )O2(0 <a<1、0<b<1、0<c<1、a+b+c=1)、LiNi 1-y Co y O2(0 <y<1)、LiCo 1-y Mn y O2, LiNi 1-y Mny O2(0 < y < 1), Li(Ni a Co b Mn c )O4(0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-z Ni z O4(0 < z < 2), LiMn 2-z Co z O4(0 < z < 2) and combinations thereof.

[0062] The conductive material for the positive electrode can also be used without limitation as long as it can be used as the conductive material for the positive electrode of a conventional lithium-ion secondary battery. For example, the conductive material for the positive electrode can be a conventional material such as carbon nanotubes (single-walled carbon nanotubes, multi-walled carbon nanotubes) or carbon black. In some aspects of the present invention, the conductive material can be selected from graphite, carbon black, carbon fiber or metal fiber, metal powder, conductive whisker, conductive metal oxide, activated carbon or polyphenylene derivative. More specifically, the positive electrode conductive material can be selected from the group consisting of natural graphite, artificial graphite, super-p TM , acetylene black, Ketjen black TM , channel black, furnace black, lamp black, thermal black, Denka black TM , aluminum powder, nickel powder, zinc oxide, potassium titanate and titanium oxide, at least one conductive material from the group.

[0063] The binder for the positive electrode is mixed with the positive electrode active material and the positive electrode conductive material to bond the components, thus contributing to the growth of the particles. The binder can be an organic binder, and an organic binder refers to a binder dissolved or dispersed in an organic solvent, especially N-methylpyrrolidone (NMP), and is different from an aqueous binder using water as a solvent or dispersion medium. For example, the binder can be selected from poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride - co -hexafluoropropylene) (PVDF-co-HFP), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polyimide, polyamideimide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated-EPDM, styrene-butadiene rubber and fluororubber, but not limited thereto. In addition, the weight ratios of the positive electrode active material, the positive electrode conductive material and the binder contained in the positive electrode are also commonly used weight ratios after being appropriately adjusted.

[0064] The current collector is not limited to a specific type and may include those having high electrical conductivity and not causing chemical changes in the corresponding battery, such as stainless steel, copper, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel treated with carbon, nickel, titanium, and silver on the surface. The negative electrode may include a negative electrode active material layer including a negative electrode active material usable in a conventional lithium ion secondary battery. The negative electrode active material may be combined with a conductive material and / or an adhesive as described herein for the positive electrode active material layer. Additionally, if needed, the negative electrode includes a current collector, and the negative electrode active material layer may be located on at least one surface of the current collector.

[0065] For example, the negative electrode active material may include one or more selected from the following: carbon, such as non-graphitized carbon and graphite-based carbon; metal composite oxides, such as Li x Fe2O3 (0 ≤ x ≤ 1), Li x WO2 (0 ≤ x ≤ 1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of Groups 1, 2, and 3 of the periodic table, halogens; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides, such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, and Bi2O5; conductive polymers, such as polyacetylene; Li-Co-Ni-based materials; titanium oxide; lithium titanium oxide; and the like.

[0066] Furthermore, the present invention provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source. Specific examples of the device include, but are not limited to: power tools driven by an electric motor; electric vehicles, including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), etc.; electric two-wheel vehicles, including electric bicycles (E-bike) and electric scooters (E-scooter); electric golf carts; and power storage systems.

[0067] Hereinafter, for the purpose of helping to understand the present invention, preferred embodiments are given, but it is obvious to those skilled in the art that the embodiments are only intended to illustrate the present invention and various modifications and changes can be made within the scope and technical idea of the present invention, and these modifications and changes naturally fall within the scope of the appended claims.

[0068] [Example 1] Preparation of surface-modified solid electrolytes

[0069] First, Li6PS5Cl (manufactured by NEI Corporation) was prepared as the parent material, along with a perfluorothiol having both hydrophilic (thiol) and hydrophobic (fluoroalkyl) groups. This perfluorothiol compound and... Figure 1 The same as shown in (b) (also known as CAS No: 34143-74-3 (1H,1H,2H,2H-perfluorodecylthiol)). Each of these samples was treated in a glove box with an oxygen concentration of less than 0.5 ppm. Subsequently, Li6PS5Cl and perfluorothiol were added to a Thinky mixer at a weight ratio of 5:1 and reacted at 25 °C and 2000 rpm for 20 min to modify the surface of Li6PS5Cl. At this point, the hydrophilic groups of the perfluorothiol are chemically bonded to Li6PS5Cl, while the hydrophobic groups of the perfluorothiol are located on the outermost side of Li6PS5Cl.

[0070] [Comparative Example 1] Conventional solid electrolytes

[0071] A conventional solid electrolyte (Li6PS5Cl) without surface modification was prepared.

[0072] [Comparative Example 2] Conventional solid electrolytes

[0073] The surface of Li6PS5Cl was simply coated with sulfosuccinate salt (an anionic surfactant).

[0074] [Experimental Example 1] Structural stability evaluation of solid electrolytes

[0075] The structural stability of Li6PS5Cl was evaluated after the solid electrolytes of Example 1 and Comparative Examples 1 and 2 were exposed to moisture at 25°C and 25% relative humidity. Figure 2 The image shows the difference in structural stability between the solid electrolyte of the present invention and conventional solid electrolytes, depending on the degree of moisture exposure. Figure 3 The image shows the differences in structural stability of conventional solid electrolytes depending on the degree of moisture exposure (exposure to air).

[0076] like Figure 2 As shown, the surface-modified solid electrolyte of Example 1 was confirmed to be effective. Figure 2 The structures of Li6PS5Cl ("perfluorothiol (air-free)" and "perfluorothiol (1 day air)") remained almost unchanged even when exposed to moisture. On the other hand, the solid electrolytes of Comparative Example 1 (Li6PS5Cl, "original LPSCl" and "LPSCl exposed to air (1 day air)") without surface modification were confirmed to exhibit considerable structural changes. Furthermore, as... Figure 3As shown, the solid electrolyte of Comparative Example 2, prepared by simply coating the surface of Li6PS5Cl with a sulfosuccinate salt (sodium diethylhexyl sulfosuccinate), also exhibits a considerable structural change. From this, it can be seen that, as in this invention, when the surface of the parent material (a sulfide-containing solid electrolyte) is modified with an amphiphilic compound, protection against moisture can be provided.

[0077] [Experimental Example 2] Evaluation of ionic conductivity of solid electrolytes

[0078] The ionic conductivity of Li6PS5Cl was measured after the solid electrolytes of Example 1 and Comparative Examples 1 and 2 were exposed to moisture at 25°C and 25% relative humidity. Figure 4 and Figure 5 This is a graph showing the difference in ionic conductivity between the solid electrolyte of the present invention and a conventional solid electrolyte, depending on the degree of moisture exposure (exposure to air). Figure 6 This is a graph showing the differences in ionic conductivity of conventional solid electrolytes depending on the degree of moisture exposure (exposure to air).

[0079] like Figure 4 and Figure 5 As shown, the surface-modified solid electrolyte of Example 1 was confirmed ( Figure 4 and Figure 5 The "perfluorothiols (air-free)" and "perfluorothiols (1 day air)" maintained an ionic conductivity as high as approximately 1 mS / cm even after exposure to moisture. On the other hand, the solid electrolytes of Comparative Example 1 (Li6PS5Cl, 'raw LPSCl' and 'LPSCl (24 hours air)') without surface modification were confirmed to have an ionic conductivity as low as 0 mS / cm. Furthermore, as... Figure 6 As shown, the solid electrolyte of Comparative Example 2, which was prepared by simply coating the surface of Li6PS5Cl with a sulfosuccinate salt (sodium diethylhexyl sulfosuccinate), had a higher ionic conductivity than the solid electrolyte of Comparative Example 1, but lower than that of the solid electrolyte of Example 1.

Claims

1. A solid electrolyte for all-solid-state batteries, comprising: Solid electrolytes, including solid electrolytes containing sulfides; and A modified layer located on the surface of the solid electrolyte, the modified layer comprising an amphiphilic compound, wherein the amphiphilic compound comprises at least one hydrophilic group and at least one hydrophobic group. Wherein, the hydrophilic group of the amphiphilic compound is at least one selected from the group consisting of thiol group, amino group, isocyanate group, and ethoxysilyl group, and The hydrophobic group of the amphiphilic compound is a hydrocarbon group that has been substituted for a fluorinated or organosilicon compound.

2. The solid electrolyte for all-solid-state batteries as described in claim 1, wherein, The solid electrolyte comprises bonds between the hydrophilic groups of the amphiphilic compound and the surface of the sulfide-containing solid electrolyte.

3. The solid electrolyte for all-solid-state batteries as described in claim 1, wherein, The amphiphilic compound is a compound containing perfluorothiols.

4. The solid electrolyte for all-solid-state batteries as described in claim 3, wherein, The perfluorothiol-containing compound is a C1-C30 aliphatic or aromatic hydrocarbon substituted with 1 to 20 fluorine groups and 1 to 5 thiol groups.

5. The solid electrolyte for all-solid-state batteries as described in claim 4, wherein, The perfluorothiol-containing compound is a C8-C12 hydrocarbon substituted with 15 to 20 fluorine groups and 1 to 3 thiol groups.

6. The solid electrolyte for an all-solid-state battery as described in claim 4, wherein, The compound containing perfluorothiols is a C10 hydrocarbon substituted with 17 fluorine groups and 1 thiol group.

7. The solid electrolyte for an all-solid-state battery as described in claim 4, wherein, The compound containing perfluorothiols is CF3(CF2)7(CH2)2SH.

8. The solid electrolyte for an all-solid-state battery as described in claim 1, wherein, The sulfide-containing solid electrolyte comprises Li6PS5Cl.

9. The solid electrolyte for an all-solid-state battery as described in claim 1, wherein, Based on 100% by weight of the solid electrolyte for all-solid-state batteries, the content of the amphiphilic compound is from 5% to 30% by weight.

10. The solid electrolyte for an all-solid-state battery as described in claim 1, wherein, The thickness of the modified layer containing the amphiphilic compound is from 0.1 μm to 3 μm.

11. The solid electrolyte for an all-solid-state battery as described in claim 1, wherein, The thickness of the modified layer containing the amphiphilic compound is from 0.1 μm to 1 μm.

12. The solid electrolyte for an all-solid-state battery as described in claim 1, wherein, The thickness of the modified layer containing the amphiphilic compound is 0.3 μm to 0.5 μm.

13. The solid electrolyte for an all-solid-state battery as described in claim 3, wherein, The hydrophilic group of the perfluorothiol-containing compound is bonded to the solid electrolyte, and the hydrophobic group of the perfluorothiol-containing compound is located on the outermost side of the solid electrolyte.

14. An all-solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte as described in claim 1.

15. The all-solid-state battery as described in claim 14, wherein, The solid electrolyte is positioned as a layered membrane located between the positive electrode and the negative electrode.

16. The all-solid-state battery as claimed in claim 14, wherein, The solid electrolyte is mixed and contained in the positive electrode active material and / or the negative electrode active material.

17. The all-solid-state battery as claimed in claim 14, wherein, The all-solid-state battery is a semi-solid-state battery that further includes a liquid electrolyte.

18. A battery module comprising an all-solid-state battery, in, The all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane disposed between them. The solid electrolyte membrane comprises: Solid electrolytes, including solid electrolytes containing sulfides; and A modified layer located on the surface of the solid electrolyte, the modified layer comprising an amphiphilic compound, wherein the amphiphilic compound comprises at least one hydrophilic group and at least one hydrophobic group. Wherein, the hydrophilic group of the amphiphilic compound is at least one selected from the group consisting of thiol group, amino group, isocyanate group, and ethoxysilyl group, and The hydrophobic group of the amphiphilic compound is a hydrocarbon group that has been substituted for a fluorinated or organosilicon compound.

19. An electric vehicle comprising a battery module, the battery module including an all-solid-state battery. in, The all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane disposed between them. The solid electrolyte membrane comprises: Solid electrolytes, including solid electrolytes containing sulfides; and A modified layer located on the surface of the solid electrolyte, the modified layer comprising an amphiphilic compound, wherein the amphiphilic compound comprises at least one hydrophilic group and at least one hydrophobic group. Wherein, the hydrophilic group of the amphiphilic compound is at least one selected from the group consisting of thiol group, amino group, isocyanate group, and ethoxysilyl group, and The hydrophobic group of the amphiphilic compound is a hydrocarbon group that has been substituted for a fluorinated or organosilicon compound.

20. The electric vehicle of claim 19, wherein the electric vehicle is selected from electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric two-wheelers, or electric golf carts.

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