Binder for all-solid-state battery, binder composition, positive electrode for all-solid-state battery, and all-solid-state battery comprising same

Abstract

The present invention relates to a binder for an all-solid-state battery, comprising a main chain cross-linked by a compound containing two or more mercapto functional groups, in which the main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene-based monomer; a positive electrode for an all-solid-state battery comprising the binder for an all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte; the invention also relates to an all-solid-state battery which comprises a positive electrode, a negative electrode and a solid electrolyte layer arranged between the positive electrode and the negative electrode, and the positive electrode comprises the positive electrode for the all-solid-state battery.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Korean Patent Application No. 10-2023-0179289, filed on December 12, 2023, and Korean Patent Application No. 10-2024-0170013, filed on November 25, 2024, the disclosures of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present invention relates to an adhesive for an all-solid-state battery, an adhesive composition, a positive electrode for an all-solid-state battery, and an all-solid-state battery comprising the positive electrode. Background Art

[0004] Although lithium secondary batteries have been mainly used in small devices such as mobile devices and laptop computers, recent research has expanded to large and medium-sized devices such as energy storage systems (ESS) and electric vehicles (EVs).

[0005] Unlike small batteries, these large and medium-sized lithium secondary batteries operate in harsher environments (such as temperature and shock) and require more batteries to be used, so safety, good performance and affordable prices must be guaranteed.

[0006] Currently, most commercially available lithium secondary batteries use organic liquid electrolytes (lithium salts dissolved in flammable organic solvents), which pose potential risks of leakage, fire, and explosion. Therefore, the use of solid electrolytes to replace these organic liquid electrolytes has attracted much attention as an alternative solution to address these safety issues.

[0007] All-solid-state batteries consist of a positive electrode, a solid electrolyte, and a negative electrode. Both sulfides and oxides can be used as solid electrolytes for all-solid-state batteries, and sulfide solid electrolytes are the most promising materials in terms of lithium ion conductivity.

[0008] The driving mechanism of all-solid-state batteries is the transport of lithium ions through the interface between the active material and the solid electrolyte.

[0009] However, due to the continuous charging and discharging of all-solid-state batteries, the volume of the active material changes, and the interface contact with the solid electrolyte will be lost. It is known that the smaller the driving pressure of the all-solid-state battery, the more serious this situation is, so it is necessary to improve it.

[0010] [Prior art literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Korean Patent No. 10-1970648 (April 15, 2019) Summary of the Invention

[0013] [Technical Issues]

[0014] The object of the present invention is to provide an adhesive for an all-solid-state battery, which comprises a main chain, wherein the main chain is cross-linked by a compound containing two or more thiol functional groups, wherein the main chain comprises repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, wherein the main chain further comprises a polar functional group, thereby exhibiting a so-called "self-healing" property, that is, preventing the loss of interfacial contact with the solid electrolyte due to volume changes of the active material during repeated charge and discharge of the all-solid-state battery, thereby improving the initial discharge capacity and coulombic efficiency of the all-solid-state battery when operating at low voltage.

[0015] Another object of the present invention is to provide an adhesive composition for an all-solid-state battery, comprising: a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer; a compound containing two or more thiol functional groups; and an initiator.

[0016] Another object of the present invention is to provide a positive electrode for an all-solid-state battery, which comprises a binder for an all-solid-state battery, a conductive material, a positive electrode active material and a solid electrolyte.

[0017] Another object of the present invention is to provide an all-solid-state battery having improved electrochemical and lifespan characteristics by applying a positive electrode active material for an all-solid-state battery to a positive electrode.

[0018] [Technical solution]

[0019] One example of the present invention provides a binder for an all-solid-state battery, comprising a main chain cross-linked by a compound containing two or more thiol functional groups, wherein the main chain includes repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer.

[0020] The compound containing at least two thiol functional groups may be at least one selected from the group consisting of biphenyl-4,4′-dithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2′-(ethylenedioxy)diethylenethiol, poly(ethylene glycol)dithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,16-hexadecanedithiol, 2,2′-thiodiethylenethiol, tetraethylene glycol bis(3-mercaptopropionate) and ethylene glycol bis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), trimethylolpropane tris(3-mercaptopropionate) (TMPMP), dipentaerythritol hexa(3-mercaptopropionate) (DPMP), tris[(3-mercaptopropionyloxy)ethyl]isocyanurate (TEMPIC) and pentaerythritol tetrakis(3-mercaptobutyrate).

[0021] The aromatic vinyl monomer may be one or more selected from the group consisting of styrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene.

[0022] The conjugated diene monomer may be at least one selected from the group consisting of 1,2-butadiene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halogeno-1,3-butadiene.

[0023] The main chain may include 10 to 30 weight % of repeating units derived from an aromatic vinyl monomer and 70 to 90 weight % of repeating units derived from a conjugated diene-based monomer.

[0024] The compound containing two or more mercapto functional groups may be included in an amount of 0.1 to 20 parts by weight relative to 100 parts by weight of the main chain.

[0025] The backbone may also contain polar functional groups.

[0026] The polar functional group may be one or more selected from the group consisting of carboxyl, hydroxyl, amine, amide, carbonyl, ester, glycidyl, thioether, urea, thiourea, imidazole, and sulfonic acid groups.

[0027] The polar functional group may be included in an amount of 0.1 to 40 parts by weight relative to 100 parts by weight of the main chain.

[0028] Another example of the present invention provides a binder composition for an all-solid-state battery, comprising: a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer; a compound containing two or more thiol functional groups; and an initiator.

[0029] The binder for all-solid-state batteries may further contain a compound capable of imparting a polar functional group.

[0030] The adhesive composition may further comprise a solvent.

[0031] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, comprising the binder for the all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0032] The solid electrolyte may be at least one selected from the group consisting of Li2S-P2S5, Li2S-P2S5-LiX (wherein X is a halogen atom), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers, M is P, Si, Ge, B, Al, Ga or In), Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0≤x≤2) and Li 7-x PS 6-x I x (where 0≤x≤2).

[0033] The solid electrolyte may be an argyrodite-type solid electrolyte including one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0034] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery prepared using the binder composition.

[0035] Another example of the present invention provides an all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode comprises the positive electrode for the all-solid-state battery.

[0036] [Beneficial Effects]

[0037] According to the present invention, the adhesive for all-solid-state batteries comprises a main chain, which is cross-linked by a compound containing two or more thiol functional groups, wherein the main chain comprises repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers, wherein the main chain further comprises polar functional groups, which can exhibit the so-called "self-healing" property, that is, preventing the loss of interfacial contact with the solid electrolyte due to the volume change of the active material during repeated charge and discharge of the all-solid-state battery, thereby improving the initial discharge capacity and coulombic efficiency of the all-solid-state battery when operating at low voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Graphs depicting rate characteristics of all-solid-state batteries according to examples of the present invention and comparative examples.

[0039] Figure 2 Graph depicting the coulombic efficiency of all-solid-state batteries according to examples of the present invention and comparative examples.

[0040] Figure 3 The graph depicts the results of Fourier transform infrared spectroscopy (FT-IR) measurements for determining crosslinking between a compound containing two or more mercapto functional groups and a main chain in binders for all-solid-state batteries according to Examples and Comparative Examples of the present invention.

[0041] Figure 4a This is a graph showing the results of NMR spectrum (nuclear magnetic resonance) measurements, which can confirm the presence or absence of polar functional groups in the binders for all-solid-state batteries of Examples and Comparative Examples of the present invention. Figure 4b yes Figure 4a The dotted line portion is an enlarged view of the NMR spectrum (nuclear magnetic resonance) measurement results. DETAILED DESCRIPTION

[0042] The following describes examples of the present invention in detail. The terms and words used in this specification and claims should not be interpreted according to their conventional meanings or dictionary meanings, but should be interpreted based on the principle that the inventor can appropriately define the concept of the term to best describe his invention, with the principle of meaning and concept consistent with the technical idea of ​​the present invention. Therefore, it should be understood that the configurations described in the examples described herein are only the most preferred examples of the present invention and do not represent the entire technical idea of ​​the present invention. Various equivalents and variations that can replace them may exist at the time of application.

[0043] Throughout the specification, when any part “comprises” any component, it means that it can include more other components, rather than excluding other components, unless explicitly stated otherwise.

[0044] Furthermore, descriptions that limit or further define a component may apply to any invention and are not limited to any particular invention unless otherwise stated.

[0045] Furthermore, in the description and claims of the present invention, singular terms include plural terms unless otherwise specified.

[0046] In addition, in the description and claims of the present invention, "or" includes "and" unless otherwise stated. Therefore, "including A or B" means all three cases: including A, including B, or including A and B. In addition, all numerical ranges include the values ​​at both ends and all intermediate values ​​therebetween, unless explicitly stated to be excluded.

[0047] <Adhesives for all-solid-state batteries>

[0048] Hereinafter, a binder for an all-solid-state battery according to one embodiment of the present invention will be described.

[0049] The present invention relates to an adhesive for all-solid-state batteries that can prevent interfacial contact loss between active materials (particularly positive electrode active materials) and solid electrolytes during repeated charge and discharge of all-solid-state batteries, thereby improving initial discharge capacity and coulombic efficiency when operated at low voltages. The adhesive for all-solid-state batteries can refer to an adhesive prepared by an adhesive manufacturing process, or can refer to an adhesive formed within a positive electrode, prepared using the adhesive composition described herein.

[0050] In order to form a stable interface between the positive electrode active material and the solid electrolyte in the all-solid-state battery electrode, coating technology, single crystal active material technology and functional polymer technology for suppressing electrochemical-mechanical stress have been studied. Among them, the development of functional polymer technology is attracting attention as an effective method, especially due to its ability to suppress electrochemical-mechanical stress at the battery level.

[0051] Conventionally, the ability of non-polar rubber-like polymers to suppress electrochemical mechanical stress is enhanced by introducing polar functional groups or forming a three-dimensional structure.

[0052] However, there are limitations in suppressing irreversible interfacial contact losses, which occur when the stress experienced by all-solid-state batteries exceeds a certain level.

[0053] In order to solve the above problems, the present invention provides an adhesive for an all-solid-state battery, which comprises a main chain, wherein the main chain is cross-linked by a compound containing two or more thiol functional groups, wherein the main chain includes repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers, wherein the main chain also contains polar functional groups, thereby exhibiting the so-called "self-healing" property, that is, preventing the loss of interfacial contact with the solid electrolyte due to the volume change of the active material during repeated charge and discharge of the all-solid-state battery, thereby improving the initial discharge capacity and coulombic efficiency of the all-solid-state battery when operating at low voltage.

[0054] An all-solid-state battery binder according to one embodiment of the present invention may comprise a main chain cross-linked by a compound containing two or more thiol functional groups, wherein the main chain comprises repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer. The above-mentioned internal binder for all-solid-state batteries can be manufactured as a separate product, or an all-solid-state battery binder having the above-mentioned internal structure can be formed inside the manufactured positive electrode. In other words, the binder may also refer to a binder prepared using the following binder composition and formed inside the positive electrode.

[0055] By virtue of a main chain containing repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers and forming a cross-linked structure through a compound containing two or more thiol functional groups, this adhesive for all-solid-state batteries can improve the ability to suppress the electrochemical-mechanical stress generated inside the all-solid-state battery during the charging and discharging process of the all-solid-state battery.

[0056] The main chain of the binder for an all-solid-state battery comprises repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, thereby containing an unsaturated double bond within the main chain. A thiol-ene reaction occurs between the thiol groups at the terminal portion of the compound containing two or more thiol-functional groups and the unsaturated double bond within the main chain, generating a thiol radical. The thiol-ene reaction is a reaction between the thiol groups of the compound containing two or more thiol-functional groups and the repeating units derived from an aromatic vinyl monomer or a conjugated diene monomer in the main chain, generating an alkyl sulfide bond through the reaction of free radicals generated by ultraviolet irradiation or heat treatment with the unsaturated double bond. This reaction has the advantage of forming a polymer very quickly and in high yield under mild conditions.

[0057] Specifically, in a compound containing two or more thiol groups, one thiol group forms a thioether bond with an unsaturated double bond of the first main chain, and the other thiol group forms a thioether bond with an unsaturated double bond of the second main chain, thereby forming a cross-linked structure between the different main chains. The binder for all-solid-state batteries formed in this manner can prevent loss of interfacial contact with the solid electrolyte due to volume changes in the active material caused by repeated charge and discharge in all-solid-state batteries.

[0058] In one embodiment of the present invention, the compound containing at least two thiol functional groups may be at least one selected from the group consisting of biphenyl-4,4'-dithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)diethanethiol, poly(ethylene glycol)dithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,16-hexadecanedithiol, 2,2'-thiodiethanethiol, tetraethylene glycol bis(3 -mercaptopropionate) and ethylene glycol bis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), trimethylolpropane tris(3-mercaptopropionate) (TMPMP), dipentaerythritol hexa(3-mercaptopropionate) (DPMP), tris[(3-mercaptopropionyloxy)-ethyl]isocyanurate (TEMPIC) and pentaerythritol tetrakis(3-mercaptobutyrate), specifically trimethylolpropane tris(3-mercaptopropionate) (TMPMP).

[0059] In one example of the present invention, the content of the compound containing two or more thiol functional groups can be 0.1 to 20 parts by weight relative to 100 parts by weight of the main chain, for example, more than 0.1 parts by weight, more than 1 part by weight, more than 2 parts by weight, more than 3 parts by weight, more than 4 parts by weight, more than 5 parts by weight, more than 6 parts by weight, more than 7 parts by weight, more than 8 parts by weight, more than 9 parts by weight or more than 10 parts by weight, less than 20 parts by weight, less than 19 parts by weight, less than 18 parts by weight, less than 17 parts by weight, less than 16 parts by weight, less than 15 parts by weight, less than 14 parts by weight, less than 13 parts by weight, less than 12 parts by weight or less than 11 parts by weight relative to 100 parts by weight of the main chain.

[0060] If the content of the compound containing two or more thiol functional groups is less than 0.1 parts by weight relative to 100 parts by weight of the main chain, there is a risk that insufficient crosslinking may occur between the main chains contained in the binder for all-solid-state batteries of the present invention, resulting in a decrease in the battery performance (e.g., initial discharge capacity and coulombic efficiency) of the all-solid-state battery containing the binder. If the content exceeds 20 parts by weight, excessive crosslinking may occur between the main chains, resulting in a decrease in the ductility of the binder for all-solid-state batteries, thereby reducing the effectiveness of preventing loss of interfacial contact with the solid electrolyte when the volume of the active material changes with repeated charge and discharge of the all-solid-state battery.

[0061] In one embodiment of the present invention, the repeating units derived from aromatic vinyl monomers contained in the main chain can be derived from one or more aromatic vinyl monomers selected from the group consisting of styrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene.

[0062] In addition, in one embodiment of the present invention, the repeating unit derived from the conjugated diene monomer contained in the main chain can be derived from at least one conjugated diene monomer selected from the group consisting of 1,2-butadiene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halogeno-1,3-butadiene.

[0063] In one example of the present invention, the main chain may include 10 to 30 weight % of repeating units derived from an aromatic vinyl monomer and 70 to 90 weight % of repeating units derived from a conjugated diene monomer.

[0064] In addition, the binder of the present invention can exhibit the so-called "self-healing" property by further introducing polar functional groups into the main chain. This ability prevents the loss of interfacial contact with the solid electrolyte due to the volume change of the positive electrode active material during the continuous charging and discharging process of the all-solid-state battery.

[0065] In one example of the present invention, the polar functional groups contained in the main chain can be one or more selected from the group consisting of carboxyl, hydroxyl, amine, amide, carbonyl, ester, glycidyl, thioether, urea, thiourea, imidazole and sulfonic acid groups.

[0066] For example, the polar functional group may include a first hydrogen bonding functional group that acts as a "hydrogen bond donor" and a second hydrogen bonding functional group that acts as a "hydrogen bond acceptor."

[0067] In other words, it can be understood that the main chain of the adhesive for the all-solid-state battery of the present invention contains polar functional groups, wherein the polar functional groups may include a first hydrogen bonding functional group and a second hydrogen bonding functional group, wherein the first hydrogen bonding functional group contained in the main chain forms a hydrogen bond with the second hydrogen bonding functional group contained in the main chain to prevent the volume change of the active material caused by repeated charging and discharging of the all-solid-state battery from causing loss of interfacial contact with the solid electrolyte, thereby exhibiting the so-called "self-healing" property.

[0068] The polar functional group can be a first hydrogen-bonding functional group that acts as a "hydrogen bond donor," and can be, for example, at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, an amide group, a thioether group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group, preferably a carboxyl group. When the carboxyl group in the first hydrogen-bonding functional group acts as a "hydrogen bond donor," it is understood that the hydrogen atoms in the hydroxyl moiety of the carboxyl group, excluding the carbonyl group, also play this role. Similarly, if the amine group in the first hydrogen-bonding functional group acts as a "hydrogen bond donor," it is understood that both hydrogen atoms in the amine group also play this role.

[0069] The first hydrogen-bonding functional group can be formed by mixing a compound containing both a thiol group and the first hydrogen-bonding functional group with the unsaturated double bond in the backbone of the all-solid-state battery binder of the present invention. Through ultraviolet irradiation or heat treatment, a thiol-ene reaction allows the double bond in the conjugated diene polymer to graft with the thiol group, forming an alkyl sulfide. During this process, the portion of the first hydrogen-bonding functional group in the compound containing both a thiol group and the first hydrogen-bonding functional group that is not attached to the unsaturated double bond in the backbone remains capable of forming hydrogen bonds with the second hydrogen-bonding functional group.

[0070] Compounds containing both a thiol group and a first hydrogen bonding functional group may include 3-mercaptopropionic acid, 3-mercaptopropionic ester, ethylene glycol di(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), ethoxylated trimethylolpropane tris(3-mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, polycaprolactone Tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate), 1,4-bis (3-mercaptobutyryloxy) butane, 1,3,5-tris (3-mercaptobutoxyethyl) -1,3,5-triazine-2,4,6 (1H,3H,5H) -trione, trimethylolpropane tris (3-mercaptobutyrate), etc., but not limited thereto, as long as it contains both a thiol group and a hydrogen bond functional group in one molecule, preferably 3-mercaptopropionic acid.

[0071] Furthermore, the second hydrogen-bonding functional group serving as a "hydrogen bond acceptor" may be at least one selected from the group consisting of, for example, an amine group, a carbonyl group, a carboxyl group, a hydroxyl group, an amide group, an ester group, and a glycidyl group, preferably an amine group. If the carboxyl group in the second hydrogen-bonding functional group serves as a "hydrogen bond acceptor," it is understood that the unshared electron pair of the oxygen atom of the carbonyl group in the carboxyl group serves as such; if the amine group in the second hydrogen-bonding functional group serves as a "hydrogen bond acceptor," it is understood that the unshared electron pair of the nitrogen atom of the amine group serves as such.

[0072] The second hydrogen-bonding functional group can be formed by mixing a compound containing both a thiol group and a second hydrogen-bonding functional group with the unsaturated double bond in the backbone of the all-solid-state battery binder of the present invention. Through UV light irradiation or heat treatment, a thiol-ene reaction allows the unsaturated double bond in the backbone to be grafted onto the thiol group, forming an alkyl sulfide. During this process, the portion of the second hydrogen-bonding functional group in the compound containing both a thiol group and a second hydrogen-bonding functional group that is not attached to the unsaturated double bond in the backbone remains capable of forming hydrogen bonds with the first hydrogen-bonding functional group.

[0073] The compound containing both a sulfhydryl group and a second hydrogen bonding functional group may include cysteamine, 4-aminobutane-1-thiol, 5-aminobutane-1-thiol, 1-aminopropane-2-thiol, 2-amino-1-butanethiol, 3-amino-1-butanethiol, 4-amino-2-butanethiol, 6-amino-1-hexanethiol or 7-amino-1-heptanethiol, preferably cysteamine, but is not limited thereto, as long as it contains a sulfhydryl group and a hydrogen bonding functional group in one molecule.

[0074] In one example of the present invention, based on 100 parts by weight of the main chain, the content of the polar functional group can be 0.1 parts by weight to 40 parts by weight, for example, 0.1 parts by weight or more, 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, 11 parts by weight or more, 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, 15 parts by weight or more, 16 parts by weight or more, 17 parts by weight or more, 18 parts by weight or more, 19 parts by weight or more, 20 parts by weight or more, 21 parts by weight or more, 22 parts by weight or more, 23 parts by weight or more, 24 parts by weight or more, 25 parts by weight or more, 26 parts by weight or more, 27 parts by weight or more, 28 parts by weight or more, 29 parts by weight or more, 30 parts by weight or more, 31 parts by weight or more, 32 parts by weight or more, 33 parts by weight or more, 34 parts by weight or more, 35 parts by weight or more, 36 parts by weight or more, 37 parts by weight or more, 38 parts by weight or more, 39 parts by weight or more, 40 parts by weight or more, 41 parts by weight or more, 42 parts by weight or more, 43 parts by weight or more, 44 parts by weight or more, 45 parts by weight or more, 46 parts by weight or more, 47 parts by weight or more, 48 parts by weight or more, 49 parts by weight or more, 50 parts by weight or more, 51 parts by weight or more, 5 The amount of the present invention is 20 parts by weight or more, 8 parts by weight or more, 19 parts by weight or more, or 40 parts by weight or less, 39 parts by weight or less, 38 parts by weight or less, 37 parts by weight or less, 36 parts by weight or less, 35 parts by weight or less, 34 parts by weight or less, 33 parts by weight or less, 32 parts by weight or less, 31 parts by weight or less, 30 parts by weight or less, 29 parts by weight or less, 28 parts by weight or less, 27 parts by weight or less, 26 parts by weight or less, 25 parts by weight or less, 24 parts by weight or less, 23 parts by weight or less, 22 parts by weight or less, or 21 parts by weight or less.

[0075] If the content of the main chain polar functional group is less than 0.1 parts by weight relative to 100 parts by weight, the self-repair effect brought about by including the binder for the all-solid-state battery of the present invention may be reduced, and the performance of the all-solid-state battery may be reduced; if it exceeds 40 parts by weight, there is a risk that the binder having excessive polar functional groups may remain in the electrode composite layer and produce side reactions with, for example, the sulfide solid electrolyte contained in the positive electrode for the all-solid-state battery.

[0076] <Binder composition for all-solid-state batteries>

[0077] Hereinafter, a binder composition for an all-solid-state battery according to another embodiment of the present invention will be described.

[0078] The present invention relates to an adhesive composition that can be used to manufacture a positive electrode for an all-solid-state battery.

[0079] An all-solid-state battery binder composition according to an embodiment of the present invention may include: a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer; a compound containing two or more thiol functional groups; and an initiator.

[0080] Furthermore, the adhesive composition may further include a compound capable of imparting a polar functional group.

[0081] Furthermore, the adhesive composition may be in the form of a solution further comprising a solvent.

[0082] The polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, the compound containing two or more thiol functional groups, the initiator, and the polar functional group are described above and will not be described in detail here. Furthermore, since the solvent is the same as that described in the method for preparing the binder for an all-solid-state battery described later, a detailed description thereof will also be omitted here.

[0083] In the binder, a reaction is initiated by an initiator during the drying process of manufacturing the positive electrode for an all-solid-state battery, forming a main chain cross-linked by a compound containing two or more thiol functional groups. The main chain, which includes repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, may be included in the positive electrode. In this case, the main chain may also contain a polar functional group.

[0084] In addition, since the main chain containing the above repeating unit is formed when the positive electrode is formed, the binder composition can further improve internal bonding with positive electrode components such as positive active materials, solid electrolytes and conductive materials, and adhesion to the positive current collector.

[0085] <Method for producing an adhesive for an all-solid-state battery>

[0086] Next, a method for producing an adhesive for an all-solid-state battery is provided.

[0087] In one example, the binder for an all-solid-state battery of the present invention can be prepared by adding a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, a compound containing two or more thiol functional groups, a compound capable of imparting a polar functional group, and an initiator to a solvent to prepare a mixed solution, and then drying the solution. This mixed solution can be the "binder composition for an all-solid-state battery" described above.

[0088] The polymer containing repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers is the part that becomes the main chain after the polymer is made into an adhesive. The detailed description of the repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers contained in the polymer is the same as above, so the detailed description thereof will be omitted below.

[0089] Compounds containing two or more mercapto functional groups and compounds capable of introducing polar functional groups can be linked to the main chain of the adhesive via a thiol-ene reaction involving the unsaturated double bonds of a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer and free radical formation.

[0090] The compounds containing two or more thiol functional groups and the compounds capable of introducing polar functional groups have also been described above and will not be described in detail here.

[0091] There is no limitation on the solvent, as long as it can well disperse the polymer containing repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers, the compound having two or more thiol functional groups and the compound capable of introducing polar functional groups, and does not affect its properties and does not react with the sulfide solid electrolyte. For example, it can be at least one or more selected from the group consisting of 1,1-dichloro-1-fluoroethane, dichloropropylene, cyclohexane, methylcyclohexane, ethylcyclohexane, trichloroethylene, 1,2-dichloroethylene, dichloromethane, trichloroethane, dibromomethane, pentane, 1,2-dichloroethane, heptane, hexane, xylene, toluene, butyl butyrate and n-propyl bromide.

[0092] There is no limitation on the initiator as long as it promotes the free radical reaction of the thiol groups in the compound containing two or more thiol functional groups and the compound capable of introducing polar functional groups with the unsaturated double bonds in the polymer containing repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers.

[0093] In this case, the content of the polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer relative to the solvent in the mixed solution used to prepare the all-solid-state battery binder is preferably 0.005 g / ml to 1 g / ml. If the polymer content relative to the solvent is less than 0.005 g / ml, the solvent content used to prepare the all-solid-state battery binder of the present invention may be too high, and the drying time during the production process may be unnecessarily prolonged. If it exceeds 1 g / ml, the viscosity of the mixed solution may increase excessively, and an uneven reaction may occur in the mixed solution used to prepare the all-solid-state battery binder.

[0094] Initiators may include sulfates such as potassium persulfate or ammonium persulfate; azo compounds such as 4,4-azobis(4-cyanoglycolic acid), dimethyl 2,2'-azobisisobutyrate, 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis(2-methylpropionitrile), 2,2-azobis-2-methyl-N-1,1-bis(hydroxymethyl)-2-hydroxyethylpropionamide, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile or 1,1'-azobis(1-cyclohexanecarbonitrile); peroxides such as methyl ethyl ketone peroxide, di-tert-butyl peroxide, acetyl peroxide, diisopropyl peroxide, lauroyl peroxide, benzoyl peroxide, tert-butyl peroxy(2-ethylhexanoate), diisopropyl peroxydicarbonate or di-tert-butyl peroxyisophthalate.

[0095] <Positive electrode for all-solid-state batteries>

[0096] On the other hand, one example of the present invention provides a positive electrode for an all-solid-state battery including the binder for an all-solid-state battery.

[0097] In one example, a positive electrode for an all-solid-state battery may include the above-mentioned binder for an all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0098] Since the specific content of the binder for an all-solid-state battery is the same as described above, a detailed description of the binder contained in the positive electrode for an all-solid-state battery of the present invention will be omitted below.

[0099] The content of the binder for all-solid-state batteries may be about 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight, based on 100 parts by weight of the total amount of the positive electrode for all-solid-state batteries.

[0100] In addition to the binder for the all-solid-state battery of the present invention that meets the above-mentioned content range, it may further include an acrylic binder, a polyvinylidene fluoride (PVDF) binder, a polytetrafluoroethylene (PTFE) binder or a butadiene rubber binder (such as nitrile rubber (NBR)), and various other polymer binders.

[0101] The positive electrode active material contained in the positive electrode for an all-solid-state battery is not particularly limited, as long as the material can reversibly absorb and release lithium ions. For example, it can include one or more composite compounds of cobalt, manganese, nickel, iron, or a combination thereof with lithium.

[0102] As a more specific example, a compound represented by any of the following chemical formulas can be used as the core of the positive electrode active material: Li a A 1-b R b D2 (where 0.90≤a≤1.8 and 0≤b≤0.5); Li a E 1-b R b O 2-c D c (where 0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); LiE 2-b R b O 4-c D c (where 0≤b≤0.5,0≤c≤0.05); Li a Ni 1-b-c Co b R c D α(where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α≤2); Li a Ni 1-b-c Co b R c O 2-α Z α (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni 1-b-c Co b R c O 2-α Z2 (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni 1-b-c Mn b R c D α (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α≤2); Li a Ni 1-b-c Mn b R c O 2-α Z α (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni b E c G d O2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5 and 0.001≤d≤0.1); Li a Ni b Co c Mn d G e O2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5 and 0≤e≤0.1); Li a NiG b O2 (where 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a CoG b O2 (where 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a MnG bO2 (where 0.90≤a≤1.8 and 0.001≤b≤0.1); Li a Mn2G b O4 (where 0.90≤a≤1.8 and 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(where 0≤f≤2);Li (3-f) Fe2(PO4)3 (where 0≤f≤2); and LiFePO4.

[0103] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or any combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or any combination thereof; Q is Ti, Mo, Mn or any combination thereof; T is Cr, V, Fe, Sc, Y or any combination thereof; J is V, Cr, Mn, Co, Ni, Cu or any combination thereof.

[0104] In one example, the positive active material may have a particle size of about 0.01 μm to 50 μm, and may have a secondary particle form in which a plurality of particles are aggregated and assembled.

[0105] There is no particular restriction on the conductive material contained in the positive electrode for an all-solid-state battery, as long as it is conductive and does not cause any chemical changes in the battery, for example, one or a mixture of two or more selected from the group consisting of: graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black or thermal black; conductive fibers, such as carbon fibers such as vapor grown carbon fibers (VGCF) or metal fibers; metal powders, such as fluorinated carbon powder, aluminum powder or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0106] According to an example of the present invention, based on 100% by weight of the positive electrode for all-solid-state batteries, the positive electrode for all-solid-state batteries may contain 0% to 30% by weight of a conductive material. According to a specific example of the present invention, the content of the conductive material may be 0.5% by weight or more, 1% by weight or more, 3% by weight or more, or 5% by weight or more, and may be 15% by weight or less, 10% by weight or less, 7% by weight or less, or 5% by weight or less. For example, based on 100% by weight of the positive electrode for all-solid-state batteries, the content of the conductive material may be 0.5% to 5% by weight. If the content of the conductive material exceeds the upper limit, the energy density will decrease due to the low proportion of the active material, while if the content of the conductive material is below the lower limit, the required level of electronic conductivity cannot be achieved, resulting in a lower capacity utilization rate.

[0107] For example, the solid electrolyte contained in the positive electrode for all-solid-state batteries may be a sulfide-based solid electrolyte, and among them, the sulfide-based solid electrolyte may be represented by the following formula 1.

[0108] [Formula 1]

[0109] Li k M 2 l S m X 2 n

[0110] Among them, M 2 is Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W or La, and among them, X 2 is F, Cl, Br, I, Se, Te or O, and among them, 0 < k ≤ 6, 0 < l ≤ 6, 0 < m ≤ 6 and 0 ≤ n ≤ 6.

[0111] For example, in the above formula 1, M 2 may be B, Si, Ge, P or N.

[0112] For example, in the above formula 1, X 2 may be F, Cl, Br, I or O.

[0113] For example, the sulfide-based solid electrolyte represented by the above formula 1 may be at least one selected from the group consisting of Li2S-P2S5, Li2S-P2S5-LiX (wherein X is a halogen atom), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers, M is P, Si, Ge, B, Al, Ga or In), Li 7- x PS 6-x Cl x (where 0≤x≤2), Li 7-x PS 6-x Br x (where 0≤x≤2) and Li 7-x PS 6-x I x (where 0≤x≤2).

[0114] In addition, the sulfide-based solid electrolyte may preferably be an argyrodite-type solid electrolyte containing at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0115] The positive electrode for an all-solid-state battery according to one embodiment of the present invention may include a current collector and a positive electrode active material layer formed on at least one of the current collectors, wherein the positive electrode active material layer may include the above-mentioned binder, a solid electrolyte, a conductive material, and a positive electrode active material.

[0116] The positive electrode can be prepared by any method known in the art and is not limited to a specific preparation method. It can be prepared, for example, by mixing a positive electrode active material, a solid electrolyte, a conductive material and a binder in a solvent to form a slurry phase positive electrode mixture, and then coating the positive electrode mixture on a positive electrode current collector.

[0117] The thickness of the positive electrode current collector is generally 3 μm to 500 μm. There are no particular limitations on the positive electrode current collector, as long as it has high conductivity and does not cause chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver can be used. The current collector may also have microscopic irregularities on its surface to increase the adhesion of the positive electrode active material, and may be in a variety of forms such as films, sheets, foils, meshes, porous materials, foams, and non-woven materials.

[0118] In addition to the above-mentioned positive electrode active material, solid electrolyte, conductive material and binder, the positive electrode may further include additives such as fillers, coatings, dispersants or ion conductive additives. The fillers, coatings, dispersants or ion conductive additives can be any materials commonly used in all-solid-state secondary battery electrodes.

[0119] The thickness of the positive electrode can be, for example, 70 μm to 150 μm.

[0120] <All-solid-state battery>

[0121] Another example of the present invention provides an all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode comprises the positive electrode for the all-solid-state battery.

[0122] Since the positive electrode contained in the all-solid-state battery has been described in detail above, the negative electrode and solid electrolyte contained in the all-solid-state battery will be described in detail below.

[0123] The solid electrolyte layer provided between the positive electrode and the negative electrode may include, for example, a sulfide-based solid electrolyte. This sulfide-based solid electrolyte may be the same as or different from the sulfide-based solid electrolyte contained in the positive electrode.

[0124] For specific details on sulfide-based solid electrolytes, see the previous section on the positive electrode.

[0125] The elastic modulus or Young's modulus of the solid electrolyte can be, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, or 23 GPa or less. The elastic modulus or Young's modulus of the solid electrolyte can be, for example, 10 GPa to 35 GPa, 15 GPa to 35 GPa, 15 GPa to 30 GPa, or 15 GPa to 25 GPa. By having an elastic modulus within this range, the solid electrolyte is more easily pressurized and / or sintered.

[0126] The solid electrolyte layer further comprises, for example, a binder. The binder contained in the solid electrolyte layer may be, for example, but not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., as long as it can be used as a binder in the art. The binder of the solid electrolyte layer may be the same as or different from the binder of the positive electrode active material layer and the negative electrode active material layer.

[0127] Next, the negative electrode of the all-solid-state battery may include a negative electrode current collector and a negative electrode active material layer.

[0128] The thickness of the negative electrode active material layer is, for example, less than 50%, less than 40%, less than 30%, less than 20%, less than 10% or less than 5% of the thickness of the positive electrode active material layer. The thickness of the negative electrode active material layer is, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the negative electrode active material layer is too thin, the lithium dendrites formed between the negative electrode active material layer and the negative electrode current collector will cause the negative electrode active material layer to collapse, making it difficult to improve the cycle characteristics of the all-solid-state battery. If the thickness of the negative electrode active material layer is excessively increased, the energy density of the all-solid-state battery is reduced, and the internal resistance of the all-solid-state battery is increased due to the negative electrode active material layer, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0129] The negative electrode active material layer contains, for example, a negative electrode active material that forms an alloy or a compound with lithium.

[0130] For example, the negative electrode active material contained in the negative electrode active material layer is in the form of particles. The average particle size of the negative electrode active material in particle form is, for example, less than 4 μm, less than 3 μm, less than 2 μm, less than 1 μm or less than 900 nm. The average particle size of the negative electrode active material in particle form is, for example, less than 10 nm to 4 μm, less than 10 nm to 3 μm, less than 10 nm to 2 μm, less than 10 nm to 1 μm, or less than 10 nm to 900 nm. Negative electrode active materials with an average particle size within this range are further conducive to the reversible absorption and / or desorption of lithium during charging and discharging. For example, the average particle size of the negative electrode active material can be a volume equivalent median diameter (D50) measured using a laser particle size distribution analyzer.

[0131] The negative electrode active material contained in the negative electrode active material layer includes, for example, one or more selected from carbon-based negative electrode active materials and metal or semi-metal negative electrode active materials.

[0132] The carbon-based negative electrode active material is specifically amorphous carbon. Amorphous carbon can be, for example, but not necessarily limited to, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, or any other material classified as amorphous carbon in the art. Amorphous carbon is non-crystalline or very low-crystallinity carbon, as distinguished from crystalline carbon or graphitic carbon.

[0133] The metal or semi-metal negative electrode active material includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto. Any material used in the art as a metal negative electrode active material or a semi-metal negative electrode active material and forming an alloy or compound with lithium can be used. For example, nickel (Ni) is not a metal negative electrode active material because it cannot form an alloy with lithium.

[0134] The negative electrode active material layer may include any one of these negative electrode active materials, or may include a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer includes only amorphous carbon, or includes one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn) and zinc (Zn). In another example, the negative electrode active material layer includes amorphous carbon and a mixture of one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn) and zinc (Zn). The mixing ratio of amorphous carbon to, for example, silver (Ag) is a weight ratio of 10: 1 to 1: 2, 5: 1 to 1: 1 or 4: 1 to 2: 1, but is not necessarily limited to the above range, but is selected based on the characteristics required for the all-solid-state battery. The composition of this negative electrode active material further improves the cycle characteristics of the all-solid-state battery.

[0135] The negative electrode active material contained in the negative electrode active material layer includes, for example, a mixture of first particles consisting of amorphous carbon and second particles consisting of metal or semi-metal. The metal or semi-metal includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn) and zinc (Zn). Alternatively, the semi-metal is a semiconductor. Based on the total weight of the mixture, the content of the second particles is 8% to 60% by weight, 10% to 50% by weight, 15% to 40% by weight, or 20% to 30% by weight. The content of the second particles within this range further improves, for example, the cycle characteristics of the all-solid-state battery.

[0136] The negative electrode active material layer includes, for example, a binder. For example, the binder may be, but is not necessarily limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., as long as they are used as binders in the art. The binder may be composed of one or more different binders.

[0137] The negative electrode active material layer includes a binder to stabilize the negative electrode active material layer on the negative electrode current collector. In addition, although the volume of the negative electrode active material layer changes and / or the relative position changes during the charge and discharge process, the cracking of the negative electrode active material layer is still suppressed. For example, if the negative electrode active material layer does not contain a binder, the negative electrode active material layer may easily separate from the negative electrode current collector. In the case where the negative electrode active material layer is separated from the negative electrode current collector, the negative electrode current collector is exposed to the outside and contacts the solid electrolyte layer, thereby increasing the possibility of a short circuit. The negative electrode active material layer is prepared by, for example, applying a slurry containing a material constituting the negative electrode active material layer to the negative electrode current collector and drying it. By adding a binder to the negative electrode active material layer, the negative electrode active material can be stably dispersed in the slurry. For example, when the slurry is applied to the negative electrode current collector by screen printing, clogging of the screen (for example, clogging caused by agglomerates of the negative electrode active material) can be prevented.

[0138] The negative electrode current collector is composed of, for example, a material that does not react with lithium (i.e., does not form alloys or compounds). The material constituting the negative electrode current collector may be, but is not necessarily limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), or nickel (Ni), as long as it is used as an electrode current collector in the art. The negative electrode current collector may be composed of one of the above metals, or an alloy or coating material of two or more metals. The negative electrode current collector is, for example, in the form of a plate or foil.

[0139] The negative electrode active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, dispersants, ion conductors, and the like.

[0140] All-solid-state batteries can be manufactured by, for example, separately fabricating the positive electrode, negative electrode, and solid electrolyte layers and then laminating these layers together.

[0141] The present invention also provides a battery module comprising the all-solid-state battery as a unit cell, a battery pack comprising the battery module, and a device comprising the battery pack as a power source.

[0142] Specific examples of such devices include, but are not limited to, power tools powered by electric motors; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems, etc.

[0143] Example

[0144] Specific embodiments of the present invention are described below. However, the following examples are only used to specifically illustrate or describe the present invention and are not intended to limit the present invention. In addition, any matters not described herein but that can be fully inferred by those skilled in the art will be omitted here.

[0145] Production Example 1: Production of an All-Solid-State Battery Binder and Binder Composition

[0146] (1) 0.5 g of styrene-butadiene rubber (SBR), a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, 0.03 g of trimethylolpropane tris(3-mercaptopropionate) (TMPMP), a compound containing at least two mercapto functional groups, and 0.01 g of 2,2-azobis(2-methylpropionitrile) as a thermal initiator were introduced into 9.5 g of p-xylene as a solvent to prepare a solution for preparing a binder for an all-solid-state battery. The solution was mixed at 300 rpm at 30°C and normal pressure for 12 hours to prepare a mixed solution.

[0147] (2) The mixed solution was pre-dried at 80° C. and normal pressure for 1 hour, and then vacuum-dried at 80° C. to prepare a binder for an all-solid-state battery.

[0148] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0149] Production Example 2: Production of an All-Solid-State Battery Binder and Binder Composition

[0150] (1) 0.5 g of styrene-butadiene rubber (SBR), a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, 0.135 g of 3-mercaptopropionic acid and 0.095 g of cysteamine, a compound capable of introducing a polar functional group, 0.03 g of trimethylolpropane tris(3-mercaptopropionate) (TMPMP), a compound containing at least two mercapto functional groups, and 0.01 g of 2,2-azobis(2-methylpropionitrile) as a thermal initiator were introduced into 9.5 g of p-xylene as a solvent to prepare a solution for preparing a binder for an all-solid-state battery. The solution was mixed at 300 rpm at 30° C. and normal pressure for 12 hours to prepare a mixed solution.

[0151] (2) The mixed solution was pre-dried at 80° C. and normal pressure for 1 hour, and then vacuum-dried at 80° C. to prepare a binder for an all-solid-state battery.

[0152] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0153] Comparative Manufacturing Example 1: Manufacturing of Binders and Binder Compositions for All-Solid-State Batteries

[0154] (1) 0.5 g of styrene-butadiene rubber (SBR), a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, was introduced into 9.5 g of p-xylene as a solvent to prepare a solution for preparing a binder for an all-solid-state battery. The solution was mixed at 300 rpm for 12 hours at 30°C and normal pressure to prepare a mixed solution.

[0155] (2) The mixed solution was pre-dried at 80° C. and normal pressure for 1 hour, and then vacuum-dried at 80° C. to prepare a binder for an all-solid-state battery.

[0156] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition for an all-solid-state battery.

[0157] Example 1: Manufacturing of positive electrode for all-solid-state battery

[0158] LiNi as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, Li6PS5Cl as a solid electrolyte, Super-C as a conductive material, and the binder composition prepared in Manufacturing Example 1 were mixed in a p-xylene solvent in a weight ratio of 70:27.5:1:1.5 to prepare a positive electrode slurry, which was coated on one side of an aluminum current collector having a thickness of 15 μm and pre-dried at 80°C under normal pressure for 1 hour, and then dried at 80°C to prepare a positive electrode for an all-solid-state battery.

[0159] Example 2: Manufacturing of positive electrode for all-solid-state battery

[0160] A positive electrode for an all-solid-state battery was prepared in the same manner as in Example 1, except that the binder composition prepared in Preparation Example 2 was used instead of the binder composition prepared in Preparation Example 1.

[0161] Comparative Example 1: Manufacturing of a positive electrode for an all-solid-state battery

[0162] A positive electrode for an all-solid-state battery was prepared in the same manner as in Example 1, except that the binder composition prepared in Comparative Preparation Example 1 was used instead of the binder composition prepared in Preparation Example 1.

[0163] Experimental Example 1: FT-IR spectroscopy analysis

[0164] The FT-IR spectra of the adhesive for all-solid-state batteries of the manufacturing example and the comparative example were measured by Fourier transform infrared spectroscopy (FT-IR). Figure 3 shown.

[0165] Reference Figure 3 It can be seen that the common spectrum in Preparation Example 1, Preparation Example 2 and Comparative Preparation Example 1 is attributed to SBR in the polymerized state. In addition, the 1740 cm -1 The spectrum near 1570 cm indicates that crosslinking is formed due to the addition of TMPMP. Finally, Preparation Example 2 shows a -1 The spectra near the α-mercaptopropionic acid molecule indicate the formation of hydrogen bonds between the two polar functional groups, 3-mercaptopropionic acid and cysteamine, confirming the self-healing properties of the adhesive.

[0166] Experimental Example 2: NMR spectroscopy analysis

[0167] The binders formed inside the positive electrodes for all-solid-state batteries of Example 2 and Comparative Example 1, and the binder composition for all-solid-state batteries of Comparative Example 1 were measured by nuclear magnetic resonance spectroscopy (NMR). The results are shown in FIG4 .

[0168] Referring to Figure 4 , it can be seen that the common spectrum in Example 2 and Comparative Example 1 is generated by the polymerized SBR in Comparative Example 1. In addition, the peak sizes observed near 4.9 ppm and 5.5 ppm corresponding to vinyl groups in Example 2 are smaller than those in Comparative Example 1, indicating that the binder formed within the positive electrode for the all-solid-state battery of the present invention introduces a polar functional group into the C═C of the SBR.

[0169] Experimental Example 3: Evaluation of rate characteristics and life characteristics of all-solid-state batteries

[0170] The rate characteristics and life characteristics of all-solid-state batteries including the positive electrodes of Examples 1 and 2 and Comparative Example 1 were evaluated.

[0171] The all-solid-state battery was manufactured by the following method.

[0172] 150 mg of Li6PS5Cl as solid electrolyte was loaded into the mold cell, and then a tablet was made at a pressure of 70 MPa. The positive electrodes of Examples 1, 2 and Comparative Example 1 prepared by the above process were loaded on one side of the solid electrolyte tablet, and 100 mg of Li 0.5 A composite anode, containing a mixture of In and a solid electrolyte at a weight ratio of 8:2, was loaded onto the other side and then pressurized at 370 MPa to fabricate an all-solid-state half-cell. To analyze the performance of each electrode based on operating pressure, the tightening of the bolts was adjusted to apply operating pressures of 70 MPa and 0.33 MPa, respectively. For the evaluation of the all-solid-state half-cell, the cell was sealed to prevent gas permeation and transferred to a constant-temperature chamber for subsequent electrochemical evaluations.

[0173] For the all-solid-state batteries containing the positive electrodes of Examples 1 and 2 and Comparative Example 1, the rate characteristics were evaluated by the following test method.

[0174] The rate characteristics were measured at 30°C, CC mode, operating voltage of 3.0V to 4.3V, current conditions of 0.1C-0.2C-0.5C-0.7C-1.0C-0.2C, and 5 charge and discharge cycles respectively. The results are shown in Table 1 and Figure 1 shown.

[0175] For the all-solid-state batteries containing the positive electrodes of Example 1 and Comparative Example 1, the life characteristics were evaluated by the following test methods.

[0176] The battery was charged at a rate of 0.1C (C rate) until the voltage reached 4.3V (relative to Li) and was cut off at 4.3V (relative to Li). It was then discharged at a rate of 0.2C (C rate) until the discharge voltage reached 3.0V (relative to Li) (1st cycle). The above charge and discharge test was repeated for 50 cycles to determine the capacity retention rate of the discharge capacity. The results are shown in Tables 1 and 2. Figure 2 shown.

[0177] [Table 1]

[0178]

[0179] Refer to Table 1, Figure 1 and Figure 2 , it can be seen that the all-solid-state battery comprising the positive electrode of Examples 1 and 2 exhibits better initial discharge capacity and initial coulombic efficiency at a lower driving pressure (0 MPa) than the all-solid-state battery comprising the positive electrode of Comparative Example 1. On the other hand, when the working pressure is high (70 MPa), it can be seen that the performance difference between the all-solid-state batteries comprising the positive electrodes of Examples 1, 2 and Comparative Example 1 is not obvious. It can be understood that the adhesive with "self-repairing" properties of the present invention can effectively suppress the interfacial contact loss between the active material and the solid electrolyte that occurs when the working pressure is low. In addition, it can be seen that the all-solid-state battery comprising the positive electrode of Example 2 has excellent life characteristics, wherein the main chain contained in the adhesive is cross-linked by a compound containing two or more thiol groups, and the adhesive contains polar functional groups introduced into the main chain.

[0180] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present invention defined in the appended claims also fall within the scope of the present invention.

Claims

1. An adhesive for an all-solid-state battery comprising a main chain cross-linked by a compound containing two or more thiol functional groups, in, The main chain contains repeating units derived from aromatic vinyl monomers and repeating units derived from conjugated diene monomers.

2. The adhesive for all-solid-state batteries according to claim 1, wherein The compound containing two or more thiol functional groups is at least one selected from the group consisting of biphenyl-4,4'-dithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)diethylenethiol, poly(ethylene glycol)dithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,16-hexadecanedithiol, 2,2'-thiodiethylenethiol, tetraethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), trimethylolpropane tris(3-mercaptopropionate) (TMPMP), dipentaerythritol hexa(3-mercaptopropionate) (DPMP), tris[(3-mercaptopropionyloxy)ethyl]isocyanurate (TEMPIC) and pentaerythritol tetrakis(3-mercaptobutyrate).

3. The adhesive for all-solid-state batteries according to claim 1, wherein The aromatic vinyl monomer is one or more selected from the group consisting of styrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and 1-vinyl-5-hexylnaphthalene.

4. The adhesive for all-solid-state batteries according to claim 1, wherein The conjugated diene monomer is at least one selected from the group consisting of 1,2-butadiene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and 2-halogenated-1,3-butadiene.

5. The adhesive for all-solid-state batteries according to claim 1, wherein The main chain includes 10 to 30 wt % of repeating units derived from an aromatic vinyl monomer and 70 to 90 wt % of repeating units derived from a conjugated diene monomer.

6. The adhesive for all-solid-state batteries according to claim 1, wherein The content of the compound containing two or more thiol functional groups is 0.1 parts by weight to 20 parts by weight relative to 100 parts by weight of the main chain.

7. The adhesive for all-solid-state batteries according to claim 1, wherein The backbone also contains polar functional groups.

8. The adhesive for all-solid-state batteries according to claim 7, wherein The polar functional group is one or more selected from the group consisting of carboxyl, hydroxyl, amine, amide, carbonyl, ester, glycidyl, thioether, urea, thiourea, imidazole and sulfonic acid groups.

9. The adhesive for all-solid-state batteries according to claim 7, wherein The polar functional group is present in an amount of 0.1 to 40 parts by weight relative to 100 parts by weight of the main chain.

10. A binder composition for an all-solid-state battery, comprising: a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer; a compound containing two or more thiol functional groups; and an initiator.

11. The binder composition for an all-solid-state battery according to claim 10, wherein The binder composition for an all-solid-state battery further includes a compound capable of introducing a polar functional group.

12. The binder composition for an all-solid-state battery according to claim 10, wherein The adhesive composition further comprises a solvent. 13 . A positive electrode for an all-solid-state battery, comprising the binder according to claim 1 , a conductive material, a positive electrode active material, and a solid electrolyte.

14. The positive electrode for an all-solid-state battery according to claim 10, wherein: The solid electrolyte is at least one selected from the group consisting of: Li2S-P2S5; Li2S-P2S5-LiX, wherein X is a halogen atom; Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n , where m and n are positive numbers, and Z is Ge, Zn, or Ga; Li2S-GeS2; Li2S-SiS2-Li3PO4; Li2S-SiS2-Li p MO q , where p and q are positive numbers, M is P, Si, Ge, B, Al, Ga or In; Li 7-x PS 6-x Cl x , where 0≤x≤2; Li 7-x PS 6-x Br x , where 0≤x≤2; and Li 7-x PS 6-x I x , where 0≤x≤2.

15. The positive electrode for an all-solid-state battery according to claim 10, wherein: The solid electrolyte is an argyrodite-type solid electrolyte comprising one or more selected from Li6PS5Cl, Li6PS5Br and Li6PS5I. 16 . A positive electrode for an all-solid-state battery manufactured using the binder composition according to claim 10 .

17. An all-solid-state battery comprising: positive electrode; a negative electrode; and A solid electrolyte layer is provided between the positive electrode and the negative electrode, in, The positive electrode includes the positive electrode for an all-solid-state battery according to claim 10 or 16.

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