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

Abstract

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

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0179289 filed December 12, 2023 and Korean Patent Application No. 10-2024-0170013 filed November 25, 2024, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a binder for an all-solid-state battery, a binder composition, a positive electrode for an all-solid-state battery, and an all-solid-state battery including the same. [Background technology]

[0003] Lithium secondary batteries have been mainly used in small devices such as mobile devices and laptops, but in recent years, research into them has expanded to medium- to large-sized devices such as energy storage systems (ESS) and electric vehicles (EV).

[0004] Unlike small-sized batteries, medium- to large-sized lithium secondary batteries are subject to harsh operating environments (e.g., temperature and impact) and require the use of more batteries, so they must be safe along with excellent performance and reasonable prices.

[0005] Most currently commercially available lithium secondary batteries use organic liquid electrolytes in which lithium salts are dissolved in flammable organic solvents, which poses potential risks of leakage, fire, and explosion. Therefore, the use of solid electrolytes instead of organic liquid electrolytes has been attracting attention as an alternative to overcome these safety issues.

[0006] All-solid-state batteries are composed of a positive electrode, a solid electrolyte, and a negative electrode. Sulfides and oxides can be used as the solid electrolyte for all-solid-state batteries, and sulfide-based solid electrolytes are the most promising materials from the perspective of lithium ion conductivity.

[0007] All-solid-state batteries have a driving mechanism in which lithium ions are transferred through the interface between the active material and the solid electrolyte.

[0008] However, continuous charging and discharging of the all-solid-state battery causes a volume change of the active material, which leads to detachment of the interfacial contact with the solid electrolyte. It is known that this phenomenon becomes more severe as the driving pressure of the all-solid-state battery becomes smaller, and therefore, improvements are needed to address this issue. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent No. 10-1970648 (2019.04.15) Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a binder for an all-solid-state battery, which comprises a main chain crosslinked by a compound containing two or more thiol functional groups, the main chain comprising a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and the main chain further comprising a polar functional group, thereby exhibiting so-called "self-healing" properties that prevent interfacial contact detachment from a solid electrolyte due to volume changes of an active material caused by repeated charge and discharge of the all-solid-state battery, and capable of improving the initial discharge capacity and coulombic efficiency in a low-pressure operating environment of the all-solid-state battery.

[0011] Another object of the present invention is to provide a binder composition for an all-solid-state battery, comprising: a polymer containing a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene-based monomer; a compound containing two or more thiol functional groups; and an initiator.

[0012] Another object of the present invention is to provide 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.

[0013] Another object of the present invention is to provide an all-solid-state battery having improved electrochemical properties and life characteristics by applying the positive electrode active material for the all-solid-state battery to a positive electrode. [Means for solving the problem]

[0014] One embodiment of the present invention provides a binder for an all-solid-state battery, which comprises a main chain crosslinked by a compound containing two or more thiol functional groups, and the main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer.

[0015] The compound containing two or more thiol functional groups is 4,4'-biphenyldithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)diethanethiol, poly(ethylene glycol)dithiol, glycol)dithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexaneedithiol, 1,16-hexadecanedithiol, 2,2'-thiodiethanethiol, tetraethyleneglycol bis(3-mercaptopropionate) and glycol di(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), The alkyl acrylate may be one or more selected from the group consisting of trimethylolpropane tris(3-mercaptopropionate) (PETMP), trimethylolpropane tris(3-mercaptopropionate) (TMPMP), dipentaerythritol hexakis(3-mercaptopropionate) (DPMP), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), and pentaerythritol tetrakis(3-mercaptobutylate).

[0016] The aromatic vinyl monomer may be at least one 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.

[0017] 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-halo-1,3-butadiene.

[0018] The main chain can contain 10% to 30% by weight of repeating units derived from aromatic vinyl monomers and 70% to 90% by weight of repeating units derived from conjugated diene monomers.

[0019] The compound containing two or more thiol functional groups may be contained in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the main chain.

[0020] The main chain may further include a polar functional group.

[0021] The polar functional group may be one or more selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, an amide group, a carbonyl group, an ester group, a glycidyl group, a sulfide group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group.

[0022] The polar functional group may be contained in an amount of 0.1 to 40 parts by weight based on 100 parts by weight of the main chain.

[0023] Another embodiment of the present invention provides a binder composition for an all-solid-state battery, the binder composition comprising: a polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer; a compound including two or more thiol functional groups; and an initiator.

[0024] The binder for an all-solid-state battery may further contain a compound capable of imparting a polar functional group.

[0025] The binder composition may further contain a solvent.

[0026] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, including the binder for the all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0027] The solid electrolyte may be Li2S-P2S5, Li2S-P2S5-LiX (wherein X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, or Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2) and Li 7-x PS 6-x I x (where 0≦x≦2) may be one or more of the following.

[0028] The solid electrolyte may be an argyrodite-type solid electrolyte containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0029] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, which is manufactured using the binder composition.

[0030] Yet another embodiment of the present invention provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode includes the all-solid-state battery positive electrode. [Effects of the Invention]

[0031] According to the present invention, the all-solid-state battery includes a main chain crosslinked by a compound containing two or more thiol functional groups, the main chain including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and the main chain further includes a polar functional group. This prevents interfacial contact detachment from the solid electrolyte due to volume changes of the active material caused by repeated charge and discharge of the all-solid-state battery, which is called "self-healing," and can improve the initial discharge capacity and coulombic efficiency in a low-pressure operating environment of the all-solid-state battery. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a graph showing rate characteristics of all-solid-state batteries according to examples of the present invention and comparative examples. [Figure 2] 1 is a graph showing the coulombic efficiency of all-solid-state batteries according to examples and comparative examples of the present invention. [Figure 3] 1 is a graph showing the results of Fourier transform infrared spectroscopy (FT-IR) spectrum measurement, which can confirm whether or not crosslinking of the main chain is caused by a compound containing two or more thiol functional groups in binders for all-solid-state batteries according to Examples and Comparative Examples of the present invention. [Figure 4a] FIG. 4a is a graph showing the results of NMR (Nuclear Magnetic Resonance) spectroscopy, which can confirm the presence or absence of polar functional groups in binders for all-solid-state batteries according to examples and comparative examples of the present invention. [Figure 4b]FIG. 4b is an enlarged view of the NMR spectrum (Nuclear Magnetic Resonance) measurement results of the portion indicated by the dotted line in FIG. 4a. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms and phrases used in the specification and claims should not be construed as being limited to their ordinary or dictionary meanings, but should be construed as meanings and concepts consistent with the technical concept of the present invention, based on the principle that the inventor can appropriately define the concept of terms in order to best describe his or her invention. Therefore, it should be understood that the configurations described in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not fully represent the technical concept of the present invention, and therefore, various equivalents and modifications that can replace them may exist at the time of filing this application.

[0034] Throughout this specification, when a part is said to "comprise" a certain element, this means that it can further include other elements, rather than excluding other elements, unless otherwise specified.

[0035] Furthermore, descriptions that specify elements by limiting or adding components can be applied to all inventions unless otherwise specified, and are not limited to a specific invention.

[0036] Furthermore, throughout the description and claims of this application, the singular includes the plural unless otherwise specified.

[0037] Furthermore, throughout the description of the invention and claims of this application, "or" includes "and" unless otherwise stated. Thus, "including A or B" means all three cases: including A, including B, or including A and B. Furthermore, all numerical ranges include both endpoints and all intermediate values ​​therebetween, unless expressly excluded.

[0038] <Binder for all-solid-state batteries> Hereinafter, a binder for an all-solid-state battery according to one embodiment of the present invention will be described.

[0039] The present invention relates to a binder for an all-solid-state battery that can prevent detachment of an active material, particularly a positive electrode active material, from an interface with a solid electrolyte during repeated charge-discharge cycles of the all-solid-state battery, and can improve initial discharge capacity and Coulombic efficiency in a low-pressure operating environment. The binder for an all-solid-state battery may be a binder prepared by a binder preparation process, or may refer to a binder formed inside a positive electrode prepared using a binder composition as described below.

[0040] In order to form a stable interface between the positive electrode active material and the solid electrolyte in all-solid-state battery electrodes, various technologies are being researched, including coating technology, single-crystal active material technology, and functional polymer technology for suppressing electrochemical-mechanical stress. In particular, the development of functional polymer technology is attracting attention as an effective technology because it is possible to suppress electrochemical-mechanical stress at the battery level.

[0041] Previously, in order to improve the electrochemical-mechanical stress suppression ability of non-polar rubber-based polymers, polar functional groups were introduced or the electrochemical-mechanical stress suppression ability was improved through the formation of a three-dimensional structure.

[0042] However, there is a limit to how much the irreversible interfacial detachment phenomenon that occurs when a certain level of stress is applied to an all-solid-state battery can be suppressed.

[0043] In order to solve the above-mentioned problems, the present invention provides a binder for an all-solid-state battery, which comprises a main chain crosslinked by a compound containing two or more thiol functional groups, and the main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and the main chain further comprises a polar functional group. This shows so-called "self-healing" property, which prevents interfacial contact detachment from the solid electrolyte due to volume change of the active material caused by repeated charge and discharge of the all-solid-state battery, and it has been confirmed that the initial discharge capacity and coulombic efficiency can be improved in a low-pressure operating environment of the all-solid-state battery, thereby completing the present invention.

[0044] According to one embodiment of the present invention, a binder for an all-solid-state battery includes a main chain crosslinked by a compound containing two or more thiol functional groups, and the main chain may include a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer. The internal binder for an all-solid-state battery described above may be manufactured as a separate product, or a binder for an all-solid-state battery having the internal structure described above may be formed within the manufactured positive electrode. That is, the binder may refer to a binder formed within a positive electrode manufactured using a binder composition described below.

[0045] The binder for an all-solid-state battery includes a structure in which a main chain including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer is crosslinked with a compound including two or more thiol functional groups, thereby improving the ability to suppress electrochemical-mechanical stress generated inside the all-solid-state battery during the charge and discharge process of the all-solid-state battery.

[0046] The main chain of the binder for solid-state batteries contains repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer, resulting in an unsaturated double bond within the main chain. A thiyl radical undergoes a thien-ol reaction between a thiol group located at the terminal of a compound containing two or more thiol functional groups and the unsaturated double bond within the main chain, resulting in the formation of a sulfide bond between the main chain and the compound containing two or more thiol functional groups. The thien-ol reaction is a reaction in which radicals generated by UV irradiation or heat treatment form alkyl sulfides between the thiol group of the compound containing two or more thiol functional groups and the unsaturated double bond contained in the repeating units derived from an aromatic vinyl monomer or a conjugated diene monomer contained in the main chain. This reaction has the advantage of enabling very rapid and high-yield polymer formation under mild conditions.

[0047] That is, one thiol functional group of a compound containing two or more thiol functional groups forms a sulfide bond with an unsaturated double bond of a first main chain, and the other thiol functional group forms a sulfide bond with an unsaturated double bond of a second main chain, thereby forming a crosslinked structure between different main chains. In the case of the binder for an all-solid-state battery according to the present invention formed in this manner, it is possible to impart an effect of preventing interfacial contact detachment from a solid electrolyte due to volume change of an active material caused by repeated charge and discharge of an all-solid-state battery.

[0048] In one embodiment of the present invention, the compound containing two or more thiol functional groups is 4,4'-biphenyldithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)diethanethiol, poly(ethylene glycol)dithiol, or poly(ethylene glycol)dithiol. glycol)dithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexaneedithiol, 1,16-hexadecanedithiol, 2,2'-thiodiethanethiol, tetraethyleneglycol bis(3-mercaptopropionate) and glycol di(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), PETMP), trimethylolpropane tris(3-mercaptopropionate) (TMPMP), dipentaerythritol hexakis(3-mercaptopropionate) (DPMP), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (The solvent may be one or more selected from the group consisting of TEMPIC and pentaerythritol tetrakis(3-mercaptobutylate), and specifically, trimethylolpropane tris(3-mercaptopropionate) (TMPMP) may be used.

[0049] In one embodiment of the present invention, the compound containing two or more thiol functional groups may be included in an amount of 0.1 to 20 parts by weight, for example, 0.1 part 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, or 10 parts by weight or more, or 20 parts by weight or less, 19 parts by weight or less, 18 parts by weight or less, 17 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, 14 parts by weight or less, 13 parts by weight or less, 12 parts by weight or less, or 11 parts by weight or less, based on 100 parts by weight of the main chain.

[0050] 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, cross-linking between the main chains contained in the binder for an all-solid-state battery according to the present invention may not be sufficient, and the battery performance, such as the initial discharge capacity and coulombic efficiency, of the all-solid-state battery containing the same may be reduced. If the content exceeds 20 parts by weight, cross-linking between the main chains may be excessively formed, and the ductility of the binder for an all-solid-state battery may be reduced, resulting in a reduced effect of preventing interfacial contact detachment with the solid electrolyte due to volumetric changes of the active material caused by repeated charging and discharging of the all-solid-state battery.

[0051] In one embodiment of the present invention, the repeating units derived from the aromatic vinyl monomer contained in the main chain may 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.

[0052] In addition, in one embodiment of the present invention, the repeating unit derived from a conjugated diene monomer contained in the main chain may be derived from one or more conjugated diene monomers 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-halo-1,3-butadiene.

[0053] In one embodiment of the present invention, the main chain may contain 10% to 30% by weight of repeating units derived from aromatic vinyl monomers and 70% to 90% by weight of repeating units derived from conjugated diene monomers.

[0054] In addition, in the case of the binder according to the present invention, the main chain further contains a polar functional group, which can impart so-called "self-healing" properties, thereby preventing detachment of the interfacial contact between the positive electrode active material and the solid electrolyte due to volume change during continuous charge / discharge of the all-solid-state battery.

[0055] In one embodiment of the present invention, the polar functional group contained in the main chain may be at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, an amide group, a carbonyl group, an ester group, a glycidyl group, a sulfide group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group.

[0056] 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."

[0057] That is, the main chain constituting the binder for an all-solid-state battery according to the present invention may contain a polar functional group, and the polar functional group may include the first and second hydrogen-bonding functional groups. 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, thereby preventing the phenomenon of interfacial contact detachment with the solid electrolyte caused by volume changes of the active material due to repeated charging and discharging of the all-solid-state battery, and can be understood to exhibit so-called "self-healing properties."

[0058] The first hydrogen-bonding functional group capable of functioning as a "hydrogen bond donor" as such a polar functional group may be, for example, one or more selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, an amide group, a sulfide group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group, and is preferably a carboxyl group. In this regard, when a carboxyl group in the first hydrogen-bonding functional group functions as a "hydrogen bond donor," it can be understood that the hydrogen atom in the hydroxyl group, excluding the carbonyl group, of the carboxyl group, fulfills this role. Similarly, when an amine group in the first hydrogen-bonding functional group fulfills the role of a "hydrogen bond donor," it can be understood that the two hydrogen atoms in the amine group fulfill this role.

[0059] The first hydrogen-bonding functional group may be formed by mixing an unsaturated double bond in the main chain contained in the binder for an all-solid-state battery according to the present invention with a compound containing both a thiol group and the first hydrogen-bonding functional group, and then irradiating the mixture with UV light or heat treating the mixture, whereby the double bond in the conjugated diene polymer and the thiol group are grafted to form an alkyl sulfide through the thien-ol reaction, and in the compound containing both a thiol group and the first hydrogen-bonding functional group, the portion of the first hydrogen-bonding functional group that is not linked to the unsaturated double bond in the main chain remains in a state capable of forming a hydrogen bond with the second hydrogen-bonding functional group.

[0060] Examples of such compounds containing both a thiol group and a first hydrogen-bonding functional group include 3-mercaptopropionic acid, 3-mercaptopropionate, ethylene glycol di(3-mercaptopropionate), trimethylolpropane tri(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), dipentaerythritol hexa(3-mercaptopropionate), ethoxylated trimethylolpropane tri(3-mercaptopropionate), tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, polycaprolactone, and the like. Examples include lactone tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and trimethylolpropane tris(3-mercaptobutyrate), but there are no particular restrictions on the type as long as the compound contains both a thiol group and a hydrogen-bonding functional group in one molecule. Preferably, 3-mercaptopropionic acid may be used.

[0061] The second hydrogen-bonding functional group capable of serving as a "hydrogen bond acceptor" may be, for example, one or more selected from the group consisting of an amine group, a carbonyl group, a carboxyl group, a hydroxyl group, an amide group, an ester group, and a glycidyl group, and is preferably an amine group. In this case, when a carboxyl group serves as a "hydrogen bond acceptor" in the second hydrogen-bonding functional group, it can be understood that the lone electron pair of the oxygen atom of the carbonyl group contained in the carboxyl group fulfills that role, and when an amine group serves as a "hydrogen bond acceptor" in the second hydrogen-bonding functional group, it can be understood that the lone electron pair of the nitrogen atom contained in the amine group fulfills that role.

[0062] The second hydrogen-bonding functional group may be formed by mixing the unsaturated double bond in the main chain contained in the binder for an all-solid-state battery according to the present invention with a compound containing both a thiol group and a second hydrogen-bonding functional group, and then irradiating the mixture with UV light or heat treating the mixture, whereby the unsaturated double bond in the main chain and the thiol group are grafted to form an alkyl sulfide through a thien-ol reaction, and in the compound containing both a thiol group and a second hydrogen-bonding functional group, the portion of the second hydrogen-bonding functional group that is not linked to the unsaturated double bond in the main chain remains in a state capable of forming a hydrogen bond with the first hydrogen-bonding functional group.

[0063] The compound containing both a thiol group and a second hydrogen-bonding functional group may be any compound containing both a thiol group and a hydrogen-bonding functional group in one molecule, and examples thereof 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-hexenethiol, and 7-amino-1-heptenethiol. Preferably, cysteamine may be used.

[0064] In one embodiment of the present invention, the polar functional group may be contained in an amount of 0.1 to 40 parts by weight relative to 100 parts by weight of the main chain, 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. or more, or 20 parts by weight or more, and may be contained in an amount of 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.

[0065] If the content of the polar functional group is less than 0.1 parts by weight relative to 100 parts by weight of the main chain, the self-healing effect that can be imparted by the inclusion of the binder for an all-solid-state battery according to the present invention may be reduced, and the performance of the all-solid-state battery may be reduced. If the content exceeds 40 parts by weight, the binder having an excess polar functional group may remain in the electrode mixture layer and cause a side reaction with, for example, a sulfide-based solid electrolyte contained in the electrode, i.e., the positive electrode of the all-solid-state battery.

[0066] <Binder composition for all-solid-state batteries> Hereinafter, a binder composition for an all-solid-state battery according to another embodiment of the present invention will be described.

[0067] The present invention relates to a binder composition that can be used in the production of a positive electrode for an all-solid-state battery.

[0068] A binder composition for an all-solid-state battery according to one embodiment of the present invention may include a polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer; a compound including two or more thiol functional groups; and an initiator.

[0069] The binder composition may further contain a compound capable of imparting a polar functional group.

[0070] The binder composition may be in the form of a solution further containing a solvent.

[0071] The polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, the compound including two or more thiol functional groups, the initiator, and the polar functional group are the same as those described above, and therefore detailed descriptions thereof will be omitted below. Also, the solvent is the same as that described in the method for producing a binder for an all-solid-state battery described below, and therefore detailed descriptions thereof will be omitted.

[0072] The binder may be incorporated into the cathode in a form in which a reaction is initiated by the initiator during a drying process in the preparation of a cathode for an all-solid-state battery, forming a crosslinked main chain with a compound containing two or more thiol functional groups, the main chain including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and the main chain may further include a polar functional group.

[0073] In addition, since the binder composition forms a main chain including the repeating unit as described above while the positive electrode is being formed, the binder composition can further improve the internal binding strength with the positive electrode components, such as the positive electrode active material, solid electrolyte, and conductive material, and the adhesive strength to the positive electrode current collector.

[0074] <Method for manufacturing binder for all-solid-state batteries> Next, a method for producing a binder for an all-solid-state battery will be described.

[0075] For example, the binder for an all-solid-state battery according to the present invention may be prepared by adding a polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, a compound including 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 mixed solution. The mixed solution may correspond to the "binder composition for an all-solid-state battery" described above.

[0076] The polymer containing the repeating units derived from the aromatic vinyl monomer and the repeating units derived from the conjugated diene monomer is a portion that becomes the main chain after being produced as a binder. The repeating units derived from the aromatic vinyl monomer and the repeating units derived from the conjugated diene monomer contained in the polymer are the same as those described above, and therefore, detailed description thereof will be omitted below.

[0077] In the case of the compound containing two or more thiol functional groups or the compound capable of imparting a polar functional group, it can be linked to the main chain through a thiol-ene reaction due to radical formation with the unsaturated double bond of a polymer containing a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, which is the main chain of the binder.

[0078] The compound containing two or more thiol functional groups and the compound capable of imparting a polar functional group are also the same as those described above, and therefore, detailed description thereof will be omitted below.

[0079] The solvent is not limited to a specific type as long as it does not react with the sulfide-based solid electrolyte, does not affect the physical properties of the polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene-based monomer, the compound including two or more thiol functional groups, and the compound capable of imparting a polar functional group, and can disperse them well. For example, any one or a mixture of two or more selected from 1,1-dichloro-1-fluoroethane, propylene dichloride, cyclohexane, methylcyclohexane, ethylcyclohexane, trichloroethylene, 1,2-dichloroethylene, dichloromethane, trichloroethane, dibromomethane, pentane, 1,2-dichloroethane, heptane, hexane, xylene, toluene, butyl butyrate, and n-propyl bromide may be used.

[0080] The initiator may be of any type as long as it can promote a radical reaction between an unsaturated double bond of a polymer containing a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer and a thiol group of a compound containing two or more thiol functional groups and a compound capable of imparting a polar functional group.

[0081] In this case, the content of the polymer including 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 for preparing the binder for an all-solid-state battery is preferably 0.005 g / ml to 1 g / ml. If the content of the polymer relative to the solvent is less than 0.005 g / ml, the content of the solvent for preparing the binder for an all-solid-state battery according to the present invention will be excessive, which may unnecessarily delay the drying time during the preparation process. If the content of the polymer relative to the solvent exceeds 1 g / ml, the viscosity of the mixed solution will be excessively increased, which may cause a problem of non-uniform reaction in the mixed solution for preparing the binder for an all-solid-state battery.

[0082] Examples of the initiator include persulfates such as potassium persulfate and ammonium persulfate; 4,4-azobis(4-cyanovaleric acid), dimethyl-2,2'-azobis(2-methylpropionate), 2,2-azobis(2-amidinopropane) dihydrochloride, 2,2-azobis(2-methylpropionitrile), 2,2-azobis-2-methyl-N-1,1-bis(hydroxymethyl)-2-hydroxyethylpropioamide, 2,2'-azobis(2,4-dimethylvaleronitrile), Examples include azo compounds such as 2,2'-azobisisobutyronitrile and 1,1'-azobis(1-cyclohexanecarbonitrile); and peroxides such as methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropyl peroxydicarbonate, and di-t-butylperoxyisophthalate.

[0083] <Cathode for all-solid-state batteries> In another aspect, there is provided a positive electrode for an all-solid-state battery, comprising the binder for an all-solid-state battery according to the above-mentioned embodiment of the present invention.

[0084] In one embodiment, the positive electrode for an all-solid-state battery can include the above-mentioned binder for an all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0085] At this time, the specific details of the binder for the all-solid-state battery are the same as those described above, and therefore, a detailed description of the binder contained in the positive electrode for the all-solid-state battery according to the present invention will be omitted hereinafter.

[0086] The binder for the all-solid-state battery may be contained in an amount of 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 positive electrode for the all-solid-state battery.

[0087] Within the range satisfying the above content, in addition to the binder for an all-solid-state battery according to the present invention, an acrylic binder, a polyvinylidene fluoride (PVDF) binder, a polytetrafluoroethylene (PTFE) binder, or a butadiene rubber binder such as nitrile butadiene rubber (NBR) may be further included, and various other polymer binders may also be included.

[0088] The positive electrode active material contained in the positive electrode for the all-solid-state battery is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and may include, for example, one or more of a composite compound of a metal such as cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0089] More specifically, the core of the positive electrode active material may be a compound represented by any one of the following chemical formulas: Li a A 1-b R b D2 (wherein 0.90≦a≦1.8 and 0≦b≦0.5); Li a E 1-b R b O 2-c D c (wherein 0.90≦a≦1.8, 0≦b≦0.5, and 0≦c≦0.05); LiE 2-b R b O 4-c D c (wherein 0≦b≦0.5 and 0≦c≦0.05); Li a Ni 1-b-c Co b R c D α (wherein 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 (wherein 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, and 0<α<2); Li a Ni 1-b-c Cob R c O 2-α Z2 (wherein 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 (wherein 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 (wherein 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 (wherein 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 (wherein 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 (wherein 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 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a CoG b O2 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a MnG b O2 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a Mn2G bO4 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(0≦f≦2);Li (3-f) Fe2(PO4)3 (0≦f≦2); and LiFePO4.

[0090] 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 a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0091] In one embodiment, the positive electrode active material may have a particle size of about 0.01 μm to 50 μm, and may have the form of secondary particles assembled by agglomeration of a plurality of particles.

[0092] The conductive material contained in the positive electrode for the all-solid-state battery is not particularly limited as long as it does not induce a chemical change in the battery and has conductivity, and may include, for example, one or a mixture of two or more selected from the following conductive materials: graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber, for example, VGCF (vapor grown carbon fiber); metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.

[0093] According to one embodiment of the present invention, the positive electrode for all-solid-state battery may contain a conductive material in the range of 0 to 30% by weight based on 100% by weight of the positive electrode for all-solid-state battery. According to a specific embodiment of the present invention, the conductive material may be contained in the range of 0.5% by weight or more, 1% by weight or more, or 3% by weight or more, or 5% by weight or more within the above range, and may also be contained in the range of 15% by weight or less, 10% by weight or less, 7% by weight or less, or 5% by weight or less. For example, the conductive material may be contained in the range of 0.5 to 5% by weight based on 100% by weight of the positive electrode for all-solid-state battery. When the conductive material is contained more than the upper limit value, the ratio of the active material is low and the energy density decreases. When the conductive material is contained less than the lower limit value, the desired level of electron conductivity cannot be achieved, so the capacity manifestation rate decreases.

[0094] <00004​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​may be F, Cl, Br, I or O.

[0099] For example, sulfide-based solid electrolytes represented by the chemical formula 1 include Li2S-P2S5, Li2S-P2S5-LiX, where X is a halogen element, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n , m, n are positive numbers, Z is one of Ge, Zn or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≦x≦2, Li 7-x PS 6-x Br x , 0≦x≦2, and Li 7-x PS 6-x I x , 0≦x≦2.

[0100] Preferably, the sulfide-based solid electrolyte may be an argyrodite-type solid electrolyte containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0101] A positive electrode for an all-solid-state battery according to an embodiment of the present invention may include a current collector and a positive electrode active material layer formed on at least one side of the current collector, and the positive electrode active material layer may include the binder, solid electrolyte, conductive material, and positive electrode active material described above.

[0102] The positive electrode can be manufactured according to a method widely known in the art and is not limited to a specific manufacturing method. For example, the positive electrode can be manufactured by mixing the positive electrode active material, solid electrolyte, conductive material, binder, etc. in a solvent to manufacture a positive electrode mixture in the form of a slurry, and then applying the positive electrode mixture to a positive electrode current collector.

[0103] The positive electrode current collector is generally fabricated to a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and has high conductivity, and examples thereof include stainless steel, aluminum, nickel, titanium, baked carbon, and aluminum or stainless steel surfaces that have been surface-treated with carbon, nickel, titanium, silver, etc. The current collector can have fine irregularities on its surface to increase the adhesive strength of the positive electrode active material, and can be in various forms such as a film, sheet, foil, net, porous material, foam, nonwoven fabric, etc.

[0104] In addition to the above-described positive electrode active material, solid electrolyte, conductive material, and binder, the positive electrode may further include additives such as a filler, a coating agent, a dispersant, an ion-conductive auxiliary, etc. As the filler, coating agent, dispersant, ion-conductive auxiliary, etc., known materials generally used in electrodes of all-solid-state secondary batteries may be used.

[0105] The thickness of the positive electrode may be, for example, 70 to 150 μm.

[0106] <All-solid-state battery> Another embodiment of the present invention provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode is the above-described positive electrode for the all-solid-state battery.

[0107] The positive electrode included in the all-solid-state battery has been described in detail above, and therefore, the negative electrode and solid electrolyte included in the all-solid-state battery will be described in detail below.

[0108] The solid electrolyte layer disposed between the positive electrode and the negative electrode may include, for example, a sulfide-based solid electrolyte, which may be the same or different from the sulfide-based solid electrolyte contained in the positive electrode.

[0109] For specific details regarding the sulfide-based solid electrolyte, please refer to the above-mentioned positive electrode section.

[0110] The elastic modulus of the solid electrolyte, i.e., Young's modulus, is, 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 of the solid electrolyte, i.e., Young's modulus, is, for example, 10 to 35 GPa, 15 to 35 GPa, 15 to 30 GPa, or 15 to 25 GPa. When the solid electrolyte has an elastic modulus in such a range, pressing and / or sintering of the solid electrolyte can be carried out more easily.

[0111] The solid electrolyte layer may further include a binder. Examples of the binder included in the solid electrolyte layer include, but are not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Any binder commonly used in the art may be used. The binder in the solid electrolyte layer may be the same or different from the binders in the positive electrode active material layer and the negative electrode active material layer.

[0112] Next, the negative electrode of the all-solid-state battery can include a negative electrode current collector and a negative electrode active material layer.

[0113] The thickness of the negative electrode active material layer is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less 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 excessively thin, lithium dendrites formed between the negative electrode active material layer and the negative electrode current collector will collapse the negative electrode active material layer, 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 large, the energy density of the all-solid-state battery will decrease, and the internal resistance of the all-solid-state battery due to the negative electrode active material layer will increase, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0114] The negative electrode active material layer contains, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0115] The negative electrode active material contained in the negative electrode active material layer has, for example, a particulate form. The average particle size of the particulate negative electrode active material is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle size of the particulate negative electrode active material is, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. When the negative electrode active material has an average particle size within such a range, reversible absorbing and / or desorbing of lithium during charging and discharging may be more easily performed. The average particle size of the negative electrode active material is, for example, the volume-equivalent median diameter (D50) measured using a laser particle size distribution analyzer.

[0116] The negative electrode active material included in the negative electrode active material layer may include, for example, at least one selected from a carbon-based negative electrode active material and a metal or semimetal negative electrode active material.

[0117] The carbon-based negative electrode active material is particularly amorphous carbon. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Any amorphous carbon classified as amorphous carbon in the art is acceptable. Amorphous carbon is carbon that has no or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon.

[0118] The metal or metalloid negative electrode active material may be any metal or metalloid negative electrode active material known in the art that forms an alloy or compound with lithium, including, but not limited to, 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). For example, nickel (Ni) is not a metal negative electrode active material because it does not form an alloy with lithium.

[0119] The negative electrode active material layer may contain one of these negative electrode active materials or a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer may contain only amorphous carbon, or may contain 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). Alternatively, the negative electrode active material layer may contain a mixture of amorphous carbon and 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 weight ratio of the mixture of amorphous carbon and silver (Ag) or the like is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to these ranges and is selected depending on the required characteristics of the all-solid-state battery. When the negative electrode active material has such a composition, the cycle characteristics of the all-solid-state battery are further improved.

[0120] The negative electrode active material layer includes a mixture of first particles made of amorphous carbon and second particles made of a metal or metalloid. Examples of the metal or metalloid include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Other examples of the metalloid include semiconductors. The content of the second particles is 8 to 60 wt %, 10 to 50 wt %, 15 to 40 wt %, or 20 to 30 wt %, based on the total weight of the mixture. The content of the second particles within this range can further improve the cycle characteristics of, for example, an all-solid-state battery.

[0121] The negative electrode active material layer includes, for example, a binder. Examples of binders include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. Any binder commonly used in the art can be used. The binder can be a single binder or a combination of multiple different binders.

[0122] The inclusion of a binder in the negative electrode active material layer stabilizes the negative electrode active material layer on the negative electrode current collector. Furthermore, cracking of the negative electrode active material layer is suppressed despite volume changes and / or changes in relative position of the negative electrode active material layer during charge / discharge cycles. For example, if the negative electrode active material layer does not contain a binder, the negative electrode active material layer can easily separate from the negative electrode current collector. When the negative electrode active material layer separates from the negative electrode current collector, the negative electrode current collector is exposed and comes into contact with the solid electrolyte layer, increasing the possibility of short circuiting. The negative electrode active material layer is produced, for example, by applying a slurry containing dispersed materials for the negative electrode active material layer to the negative electrode current collector and drying the slurry. The inclusion of a binder in the negative electrode active material layer allows for stable dispersion of the negative electrode active material in the slurry. For example, when applying the slurry to the negative electrode current collector by screen printing, clogging of the screen (e.g., clogging due to aggregates of the negative electrode active material) can be suppressed.

[0123] The negative electrode current collector is made of, for example, a material that does not react with lithium, i.e., does not form any alloys or compounds. Materials constituting the negative electrode current collector include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material commonly used as an electrode current collector in the art can be used. The negative electrode current collector can be made of one of the aforementioned 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.

[0124] The negative electrode active material layer can further contain additives used in conventional all-solid-state batteries, such as fillers, dispersants, ion conductive materials, and the like.

[0125] An all-solid-state battery can be produced, for example, by producing a positive electrode, a negative electrode, and a solid electrolyte layer, and then laminating these layers.

[0126] 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.

[0127] Specific examples of the device include, but are not limited to, power tools powered by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0128] Specific examples of the present invention will be presented below. However, the examples described below are merely for the purpose of specifically illustrating or explaining the present invention, and the present invention is not limited thereby. Furthermore, the content not described here can be fully inferred by a person skilled in the art, and therefore, a description thereof will be omitted.

[0129] Production Example 1: Production of binder and binder composition for all-solid-state battery (1) A solution for preparing a binder for an all-solid-state battery was prepared by adding 9.5 g of p-xylene as a solvent, 0.5 g of styrene-butadiene rubber (SBR) as 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) as a compound containing two or more thiol functional groups, and 0.01 g of 2,2-azobis(2-methylpropionitrile) as a thermal initiator. The solution was mixed at 300 rpm at 30°C and atmospheric pressure for 12 hours to prepare a mixed solution.

[0130] (2) The mixed solution is pre-dried at 80°C and normal pressure for 1 hour, and then vacuum-dried at 80°C to produce a binder for all-solid-state batteries.

[0131] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0132] Production Example 2: Production of binder and binder composition for all-solid-state battery (1) A solution for preparing a binder for an all-solid-state battery was prepared by adding 9.5 g of p-xylene as a solvent, 0.5 g of styrene-butadiene rubber (SBR) as 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 as compounds capable of imparting polar functional groups, 0.03 g of trimethylolpropane tris(3-mercaptopropionate) (TMPMP) as a compound containing two or more thiol functional groups, and 0.01 g of 2,2-azobis(2-methylpropionitrile) as a thermal initiator. The solution was mixed at 300 rpm at 30°C and atmospheric pressure for 12 hours to prepare a mixed solution.

[0133] (2) The mixed solution is pre-dried at 80°C and normal pressure for 1 hour, and then vacuum-dried at 80°C to produce a binder for all-solid-state batteries.

[0134] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0135] Comparative Preparation Example 1: Preparation of binder and binder composition for all-solid-state battery (1) A solution for preparing a binder for an all-solid-state battery is prepared by adding 0.5 g of styrene-butadiene rubber (SBR) as a polymer containing repeating units derived from an aromatic vinyl monomer and repeating units derived from a conjugated diene monomer to 9.5 g of p-xylene as a solvent. The solution is mixed at 30°C and atmospheric pressure for 12 hours at 300 rpm to prepare a mixed solution.

[0136] (2) The mixed solution is pre-dried at 80°C and normal pressure for 1 hour, and then vacuum-dried at 80°C to produce a binder for all-solid-state batteries.

[0137] The solution for preparing a binder for an all-solid-state battery corresponds to a binder composition for an all-solid-state battery.

[0138] Example 1: Production of positive electrode for all-solid-state battery 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 p-xylene as the binder composition prepared in Preparation Example 1 were mixed in a solvent at a weight ratio of 70:27.5:1:1.5 to prepare a cathode slurry. The slurry was applied to one side of an aluminum current collector having a thickness of 15 μm, and then pre-dried at 80°C and atmospheric pressure for 1 hour, followed by drying at 80°C to prepare a cathode for an all-solid-state battery.

[0139] Example 2: Production of positive electrode for all-solid-state battery 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 prepared in Preparation Example 1.

[0140] Comparative Example 1: Production of positive electrode for all-solid-state battery 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 prepared in Preparation Example 1.

[0141] Experimental Example 1: FT-IR Spectroscopic Analysis The FT-IR spectra of the binders for all-solid-state batteries according to the Production Example and Comparative Production Example were measured by Fourier transform infrared spectroscopy (FT-IR), and the results are shown in FIG.

[0142] 3, it can be seen that the common spectrum shown in all of Production Example 1, Production Example 2, and Comparative Production Example 1 is due to SBR in a polymeric state. -1 The spectra around 1570 cm are shown in both Production Examples 1 and 2, indicating that cross-linking occurs when TMPMP is added. -1The spectrum around this region shows that the two mixed polar functional groups, 3-mercaptopropionic acid and cysteamine, form hydrogen bonds, which confirms the fact that the binder has self-healing properties.

[0143] Experimental Example 2: NMR Spectroscopic Analysis The NMR spectra of the binders formed inside the positive electrodes for all-solid-state batteries according to Example 2 and Comparative Example 1, and the binder composition for all-solid-state batteries according to Comparative Production Example 1, were measured by NMR (nuclear magnetic resonance spectroscopy), and the results are shown in FIG. 4.

[0144] 4, it can be seen that the common spectrum shown in both Example 2 and Comparative Example 1 is due to the polymeric SBR obtained in Comparative Preparation Example 1. In addition, the magnitude of the peaks near 4.9 ppm and 5.5 ppm, which correspond to vinyl groups, is smaller in Example 2 than in Comparative Example 1, confirming that polar functional groups are introduced into the C=C double bonds present in the SBR in the binder formed inside the cathode after fabricating the cathode for an all-solid-state battery according to the present invention.

[0145] Experimental Example 3: Evaluation of rate characteristics and life characteristics of all-solid-state batteries The rate characteristics and life characteristics of the all-solid-state batteries including the positive electrodes according to Examples 1 and 2 and Comparative Example 1 were evaluated.

[0146] The all-solid-state battery was manufactured by the following method.

[0147] 150 mg of Li6PS5Cl as a solid electrolyte was loaded into a mold cell and then pelletized under a pressure of 70 MPa. The positive electrodes prepared in Examples 1 and 2 and Comparative Example 1 were loaded on one side of the solid electrolyte pellet, and Li was loaded on the other side. 0.5An all-solid-state half-cell was fabricated by loading 100 mg of a composite anode, consisting of an 8:2 weight ratio of In and solid electrolyte, and applying a pressure of 370 MPa. To analyze the performance of each electrode under different driving pressures, the bolt fastening strength was adjusted to apply driving pressures of 70 MPa and 0.33 MPa, respectively. To evaluate the all-solid-state half-cell, the battery was sealed to prevent air from penetrating inside, then transferred to a constant-temperature chamber and subjected to the following electrochemical evaluations.

[0148] The rate characteristics of the all-solid-state batteries including the positive electrodes according to Examples 1 and 2 and Comparative Example 1 were evaluated by the following test method.

[0149] The rate characteristics were measured by charging and discharging the battery five times each at a driving voltage of 3.0 V to 4.3 V in CC mode at 30°C under the current conditions of 0.1 C, 0.2 C, 0.5 C, 0.7 C, 1.0 C, and 0.2 C. The results are shown in Table 1 below and Figure 1.

[0150] The life characteristics of the all-solid-state batteries including the positive electrodes according to Example 1 and Comparative Example 1 were evaluated by the following test method.

[0151] The cells were charged at a rate of 0.1 C until the voltage reached 4.3 V (vs. Li), and then cut off at 4.3 V (vs. Li). Subsequently, the cells were discharged at a rate of 0.2 C until the voltage reached 3.0 V (vs. Li). st The above charge / discharge test was repeated 50 times, and the capacity retention rate of the discharge capacity was measured. The results are shown in Table 1 below and FIG. 2.

[0152] [Table 1]

[0153] Referring to Table 1, FIGS. 1 and 2, it can be seen that the all-solid-state batteries including the cathodes of Examples 1 and 2 exhibit superior initial discharge capacity and initial coulombic efficiency compared to the all-solid-state battery including the cathode of Comparative Example 1 at a low driving pressure (0 MPa). On the other hand, at a high driving pressure (70 MPa), the difference in performance between the all-solid-state batteries including the cathodes of Examples 1 and 2 and Comparative Example 1 is negligible. This suggests that the binder having "self-healing properties" according to the present invention is effective in suppressing the interfacial detachment phenomenon between the active material and the solid electrolyte that occurs at low driving pressures. Furthermore, in terms of battery life characteristics, it can be seen that the all-solid-state battery including the cathode of Example 2, which includes a binder in which crosslinks are formed by a compound containing two or more thiol groups in the main chain and in which polar functional groups have been introduced into the main chain, is the most excellent.

[0154] 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 concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. a backbone crosslinked by a compound containing two or more thiol functional groups, the main chain contains a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, Binder for solid-state batteries.

2. The compound containing two or more thiol functional groups includes 4,4'-biphenyldithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)diethanethiol, and poly(ethylene glycol)dithiol. glycol dithiol), 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,16-hexadecanedithiol, 2,2'-thiodiethanethiol, tetraethyleneglycol bis(3-mercaptopropionate), and glycol di(3-mercaptopropionate). Di(3-mercaptopropionate)), pentaerythritol tetrakis(3-mercaptopropionate) (pentaerythritol tetrakis(3-mercaptopropionate), PETMP), trimethylolpropane tris(3-mercaptopropionate) (trimethylolpropane tris(3-mercaptopropionate), TMPMP), dipentaerythritol hexakis(3-mercaptopropionate), DPMP), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), and pentaerythritol tetrakis(3-mercaptobutylate), The binder for an all-solid-state battery according to claim 1 .

3. The aromatic vinyl monomer is at least one 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. The binder for an all-solid-state battery according to claim 1 .

4. 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-halo-1,3-butadiene; The binder for an all-solid-state battery according to claim 1 .

5. the main chain contains 10% by weight or more and 30% by weight or less of repeating units derived from aromatic vinyl monomers and 70% by weight or more and 90% by weight or less of repeating units derived from conjugated diene monomers, The binder for an all-solid-state battery according to claim 1 .

6. The compound containing two or more thiol functional groups is contained in an amount of 0.1 parts by weight or more and 20 parts by weight or less relative to 100 parts by weight of the main chain. The binder for an all-solid-state battery according to claim 1 .

7. The backbone further comprises a polar functional group. The binder for an all-solid-state battery according to claim 1 .

8. the polar functional group is at least one selected from the group consisting of a carboxyl group, a hydroxyl group, an amine group, an amide group, a carbonyl group, an ester group, a glycidyl group, a sulfide group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group; The binder for an all-solid-state battery according to claim 7 .

9. The polar functional group is contained in an amount of 0.1 parts by weight or more and 40 parts by weight or less relative to 100 parts by weight of the main chain. The binder for an all-solid-state battery according to claim 7 .

10. a polymer comprising a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer; a compound comprising two or more thiol functional groups; and an initiator; Binder composition for all-solid-state batteries.

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

12. The binder composition further comprises a solvent. The binder composition for an all-solid-state battery according to claim 10.

13. A battery comprising the binder according to claim 1, a conductive material, a positive electrode active material, and a solid electrolyte. Positive electrode for all-solid-state batteries.

14. The solid electrolyte is Li ２ S-P ２ S ５ , Li ２ S-P ２ S ５ -LiX (where X is a halogen element), Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ , Li ２ S-SiS ２ - LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ - LiI, Li ２ S-SiS ２ -P ２ S ５ - LiI, Li ２ S-B ２ S ３ , Li ２ S-P ２ S ５ -Z ｍ S ｎ (where m and n are positive numbers, and Z is one of Ge, Zn, and Ga), Li ２ S-GeS ２ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ２ S-SiS ２ -Li ｐ MO ｑ (where p and q are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li ７－ｘ P.S. ６－ｘ Cl ｘ (where 0≦x≦2), Li ７－ｘ P.S. ６－ｘ Br ｘ (where 0≦x≦2) and Li ７－ｘ P.S. ６－ｘ I ｘ (where 0≦x≦2), The positive electrode for an all-solid-state battery according to claim 10.

15. The solid electrolyte is Li ６ P.S. ５ Cl, Li ６ P.S. ５ Br and Li ６ P.S. ５ An argyrodite-type solid electrolyte containing one or more selected from I, The positive electrode for an all-solid-state battery according to claim 10.

16. Produced using a binder composition according to claim 10. Positive electrode for all-solid-state batteries.

17. positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode; The positive electrode includes the positive electrode for an all-solid-state battery according to claim 13 or 16. All-solid-state battery.

Images