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, the binder comprising a main chain crosslinked by a compound including at least two thiol functional groups, wherein the main chain comprises an aromatic vinyl monomer-derived repeating unit and a conjugated diene-based monomer-derived repeating unit; a positive electrode for an all-solid-state battery, the positive electrode comprising the binder for a positive electrode for an all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte; and 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 includes the positive electrode for an all-solid-state battery.

Description

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

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0179289, filed December 12, 2023, and Korean Patent Application No. 10-2024-0170013, filed November 25, 2024, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] 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.

[0005] Lithium secondary batteries have been mainly applied to small fields such as mobile devices and laptop computers, but recently, the research direction is expanding to medium and large fields such as energy storage systems (ESS) and electric vehicles (EVs).

[0006] For these medium and large-sized lithium secondary batteries, unlike small ones, the operating environment (e.g., temperature, shock) is harsher, and more batteries must be used, so safety must be secured along with excellent performance and an appropriate price.

[0007] Most commercially available lithium secondary batteries utilize organic liquid electrolytes, which consist of lithium salts dissolved in flammable organic solvents. This poses a potential risk of leakage, fire, and explosion. Therefore, replacing these liquid electrolytes with solid electrolytes is gaining attention as a viable solution to address these safety concerns.

[0008] 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 of all-solid-state batteries, and from the perspective of lithium ion conductivity, a sulfide-based solid electrolyte is the most promising material.

[0009] 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.

[0010] However, as the volume of the active material changes due to continuous charging and discharging of the all-solid-state battery, detachment of the interface contact with the solid electrolyte occurs, and this is known to worsen as the driving pressure of the all-solid-state battery decreases, so improvement is needed.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) Republic of Korea Patent Registration No. 10-1970648 (April 15, 2019)

[0014] The purpose of the present invention is to provide an all-solid-state battery binder comprising a main chain crosslinked by a compound containing two or more thiol functional groups, wherein the main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, wherein the main chain further comprises a polar functional group, thereby exhibiting so-called 'self-healing' to prevent the phenomenon of delamination due to interfacial contact with a solid electrolyte according to a change in the volume of an active material due to repeated charging and discharging of an all-solid-state battery, thereby improving the initial discharge capacity and coulombic efficiency in a low-voltage driving environment of an all-solid-state battery.

[0015] Another object of the present invention is to provide a binder composition for an all-solid-state battery, comprising: 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.

[0016] Another object of the present invention is to provide a positive electrode for an all-solid-state battery comprising the above-described 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 properties and lifespan characteristics by applying the above-described all-solid-state battery positive electrode active material to the positive electrode.

[0018] One embodiment of the present invention provides an all-solid-state battery binder comprising a main chain crosslinked by a compound comprising 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.

[0019] Compounds containing two or more thiol functional groups are 4,4'-biphenyldithiol (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 (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), It may be at least one selected from the group consisting of tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC) and pentaerythritol tetrakis (3-mercaptobutylate).

[0020] The above 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.

[0021] The above 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.

[0022] The main chain may include 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.

[0023] The compound including two or more thiol functional groups may be included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the main chain.

[0024] The above main chain may further include a polar functional group.

[0025] The above polar functional group 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.

[0026] The above 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.

[0027] Another embodiment of the present invention provides an all-solid-state battery binder composition comprising: 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.

[0028] The above-mentioned all-solid-state battery binder may further include a compound capable of imparting a polar functional group.

[0029] The above binder composition may further comprise a solvent.

[0030] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, comprising the above-described binder for an all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0031] The above solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are 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 (However, 0≤x≤2), Li 7-x PS 6-x Br x (but 0≤x≤2) and Li 7-x PS 6-x I x (However, it may be one or more selected from 0≤x≤2).

[0032] The above solid electrolyte may be an argyrodite-type solid electrolyte including at least one selected from among Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0033] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, manufactured using a binder composition.

[0034] Another embodiment 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.

[0035] According to the present invention, a solid-state battery comprises a main chain crosslinked by a compound including two or more thiol functional groups, wherein the main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and wherein the main chain further comprises a polar functional group, thereby exhibiting so-called 'self-healing', which prevents the phenomenon of delamination due to interfacial contact with a solid electrolyte according to a change in the volume of an active material due to repeated charging and discharging of an all-solid-state battery, thereby improving the initial discharge capacity and coulombic efficiency in a low-voltage driving environment of an all-solid-state battery.

[0036] Figure 1 is a graph showing the rate characteristics of an all-solid-state battery according to an embodiment and a comparative example of the present invention.

[0037] Figure 2 is a graph showing the coulombic efficiency of an all-solid-state battery according to an embodiment and a comparative example of the present invention.

[0038] FIG. 3 is a graph showing the results of Fourier transform infrared spectroscopy (FT-IR) spectrum measurement that can confirm whether the main chain is crosslinked by a compound containing two or more thiol functional groups in an all-solid-state battery binder according to an example and comparative example of the present invention.

[0039] FIG. 4a is a graph showing the results of NMR spectrum (Nuclear Magnetic Resonance) measurement that can confirm the presence of polar functional groups in an all-solid-state battery binder according to an example and comparative example of the present invention, and FIG. 4b is an enlarged view showing the results of NMR spectrum (Nuclear Magnetic Resonance) measurement of the portion indicated by the dotted line in FIG. 4a.

[0040] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings. Rather, they should be interpreted with meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention. Accordingly, the configurations described in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0041] Throughout this specification, whenever a part is said to 'include' a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0042] Additionally, the description that concretizes or adds components can be applied to all inventions unless there are special limitations, and is not limited to a specific invention.

[0043] Additionally, throughout the description and claims of the invention herein, the singular includes the plural unless otherwise stated.

[0044] Additionally, throughout the description and claims of the present invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases including A, B, or both A and B. Furthermore, all numerical ranges include both extreme values ​​and all intermediate values, unless explicitly stated otherwise.

[0045]

[0046] Binder for all-solid-state batteries

[0047] Hereinafter, a binder for an all-solid-state battery according to one embodiment of the present invention will be described.

[0048] The present invention relates to a binder for an all-solid-state battery, which can prevent delamination between an active material, particularly a positive electrode active material, and a solid electrolyte interface during repeated charge and discharge operations of an all-solid-state battery, and 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 manufactured by a binder manufacturing process, or may refer to a binder formed inside a positive electrode manufactured using a binder composition as described below.

[0049] In order to form a stable interface between the positive 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. In particular, the development of functional polymer technology is attracting attention as an effective technology because it enables suppression of electrochemical-mechanical stress at the battery level.

[0050] In the past, in order to improve the electrochemical-mechanical stress suppression ability of nonpolar rubber-based polymers, the electrochemical-mechanical stress suppression ability was improved by introducing polar functional groups or forming a three-dimensional structure.

[0051] However, there is a limit to suppressing the irreversible interfacial detachment phenomenon that occurs when a certain level of stress is applied to an all-solid-state battery.

[0052] In this regard, the present invention, in order to solve the above-mentioned problems, comprises a main chain crosslinked by a compound including two or more thiol functional groups as a binder for an all-solid-state battery, wherein the main chain includes a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, and wherein the main chain further includes a polar functional group, thereby exhibiting so-called 'self-healing', which prevents the phenomenon of delamination due to interfacial contact with a solid electrolyte according to a change in the volume of an active material due to repeated charging and discharging of an all-solid-state battery, thereby confirming that the initial discharge capacity and coulombic efficiency can be improved in a low-pressure driving environment of an all-solid-state battery, thereby completing the present invention.

[0053] An all-solid-state battery binder according to one embodiment of the present invention comprises a main chain crosslinked by a compound containing two or more thiol functional groups, wherein the main chain may comprise a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer. The internal all-solid-state battery binder as described above may be manufactured as a separate product, or an all-solid-state battery binder having an internal structure as described above may be formed within a manufactured positive electrode. That is, the binder may refer to a binder formed within a positive electrode manufactured using a binder composition as described below.

[0054] The above-mentioned 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 by a compound including two or more thiol functional groups, thereby improving the ability to suppress electrochemical-mechanical stress occurring inside an all-solid-state battery during the charge and discharge process of the all-solid-state battery.

[0055] Since the main chain included in the above-mentioned all-solid-state battery binder includes an aromatic vinyl monomer-derived repeating unit and a conjugated diene monomer-derived repeating unit, it includes an unsaturated double bond in the main chain, and after a thien-ol reaction occurs between a thiol group located at the terminal portion of a compound including two or more thiol functional groups and the unsaturated double bond in the main chain, a sulfide bond is formed between the main chain and the compound including two or more thiol functional groups. The thien-ol reaction is a reaction in which an alkyl sulfide is formed from the thiol group of the compound including two or more thiol functional groups and the unsaturated double bond in the aromatic vinyl monomer-derived repeating unit or the conjugated diene monomer-derived repeating unit included in the main chain by radicals generated by UV irradiation or heat treatment, and has the advantage of being able to form a polymer very quickly and in a high yield under relaxed conditions.

[0056] That is, one thiol functional group of a compound including two or more thiol functional groups forms a sulfide bond with an unsaturated double bond of the first main chain, and the other thiol functional group forms a sulfide bond with an unsaturated double bond of the second main chain, thereby forming a cross-linking structure between different main chains, and in the case of the binder for an all-solid-state battery according to the present invention formed in this manner, it can provide an effect of preventing the phenomenon of interfacial contact detachment with a solid electrolyte due to changes in the volume of the active material due to repeated charging and discharging of the all-solid-state battery.

[0057] In one embodiment of the present invention, the compound including two or more thiol functional groups is 4,4'-biphenyldithiol (BPDT), 1,4-benzenedithiol (BDT), 2,2'-(ethylenedioxy)dieethanethiol, poly(ethylene 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), Pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), Trimethylolpropane tris(3-mercaptopropionate) (TMPMP), Dipentaerythritol hexakis(3-mercaptopropionate) (DPMP), It may be at least one selected from the group consisting of tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC) and pentaerythritol tetrakis (3-mercaptobutylate), and specifically, trimethylolpropane tris (3-mercaptopropionate) (TMPMP) can be used.

[0058] In one embodiment of the present invention, the compound including two or more thiol 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, for example, 0.1 parts by weight or more, 1 parts 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, and may be included in an amount of 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.

[0059] When the content of the compound including two or more thiol functional groups is less than 0.1 part by weight based on 100 parts by weight of the main chain, cross-linking between the main chains included in the binder for an all-solid-state battery according to the present invention may not proceed sufficiently, and thus the performance of the battery, such as the initial discharge capacity and coulombic efficiency, of the all-solid-state battery including the binder may decrease. When it exceeds 20 parts by weight, cross-linking between the main chains may be excessively formed, and as a result, the ductility of the binder for an all-solid-state battery may decrease, and thus the effect of preventing the interfacial contact detachment phenomenon with the solid electrolyte may decrease due to the volume change of the active material due to repeated charging and discharging of the all-solid-state battery.

[0060] In one embodiment of the present invention, the repeating unit derived from an aromatic vinyl monomer included in the main chain may be derived from at least one aromatic vinyl monomer 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.

[0061] In addition, in one embodiment of the present invention, the conjugated diene monomer-derived repeating unit included in the main chain may be derived from a 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-halo-1,3-butadiene.

[0062] In one embodiment of the present invention, the main chain may include 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.

[0063] In addition, in the case of the binder according to the present invention, since it further includes a polar functional group in the main chain, so-called 'self-healing' can be imparted, and thus, detachment of the interfacial contact between the solid electrolyte due to change in the volume of the positive electrode active material during continuous charging and discharging of the all-solid-state battery can be prevented.

[0064] In one embodiment of the present invention, the polar functional group included 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.

[0065] For example, the polar functional group may include a first hydrogen-bonding functional group that acts as a 'hydrogen bonding donor' and a second hydrogen-bonding functional group that acts as a 'hydrogen bonding acceptor'.

[0066] That is, the main chain constituting the binder for an all-solid-state battery according to the present invention may include a polar functional group, and the polar functional group may include the first and second hydrogen-bonding functional groups, and the first hydrogen-bonding functional group included in the main chain forms a hydrogen bond with the second hydrogen-bonding functional group included in the main chain, thereby preventing the phenomenon of interfacial contact detachment with the solid electrolyte due to changes in the volume of the active material due to repeated charging and discharging of the all-solid-state battery, which can be understood as exhibiting so-called 'self-healing'.

[0067] As such a polar functional group, the first hydrogen-bonding functional group that can act as a 'hydrogen bonding donor' may 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 sulfide group, a urea group, a thiourea group, an imidazole group, and a sulfonic acid group, and preferably a carboxyl group. At this time, when the carboxyl group in the first hydrogen-bonding functional group acts as a 'hydrogen bonding donor', it can be understood that the hydrogen atoms of the hydroxyl group portion excluding the carbonyl group among the carboxyl groups act as that role. Similarly, when the amine group in the first hydrogen-bonding functional group acts as a 'hydrogen bonding donor', it can be understood that the two hydrogen atoms of the amine group act as that role.

[0068] The first hydrogen-bonding functional group may be formed by mixing a compound including both an unsaturated double bond of the main chain and a thiol group in the compound and a first hydrogen-bonding functional group in the binder for an all-solid-state battery according to the present invention and performing UV irradiation or heat treatment, thereby grafting the double bond and the thiol group of the conjugated diene polymer through the thien-ol reaction to form an alkyl sulfide, and in the compound including both a thiol group and a first hydrogen-bonding functional group, the portion of the first hydrogen-bonding functional group that is not connected to the unsaturated double bond of the main chain may remain in a state capable of forming a hydrogen bond with the second hydrogen-bonding functional group.

[0069] 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 tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), 1,4-bis(3-mercaptobutyryloxy)butane, Examples include 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and trimethylolpropane tris(3-mercaptobutyrate), but the type may not be limited as long as it contains both a thiol group and a hydrogen bonding functional group in one molecule, and 3-mercaptopropionic acid can be preferably used.

[0070] In addition, the second hydrogen-bonding functional group that can act as a 'hydrogen bonding acceptor' may be, for example, at least one 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 preferably an amine group. At this time, when the carboxyl group in the second hydrogen-bonding functional group acts as a 'hydrogen bonding acceptor', it can be understood that the unshared electron pair of the oxygen atom of the carbonyl group included in the carboxyl group acts as that role, and when the amine group in the second hydrogen-bonding functional group acts as a 'hydrogen bonding acceptor', it can be understood that the unshared electron pair of the nitrogen atom included in the amine group acts as that role.

[0071] The second hydrogen-bonding functional group may be formed by mixing a compound including both an unsaturated double bond of the main chain and a thiol group in the compound and a second hydrogen-bonding functional group in the binder for an all-solid-state battery according to the present invention and performing UV irradiation or heat treatment, thereby grafting the unsaturated double bond of the main chain and the thiol group through the thien-ol reaction to form an alkyl sulfide, and in the compound including both a thiol group and a second hydrogen-bonding functional group, the portion of the second hydrogen-bonding functional group that is not connected to the unsaturated double bond of the main chain may remain in a state capable of forming a hydrogen bond with the first hydrogen-bonding functional group.

[0072] As long as it contains both a thiol group and a second hydrogen-bonding functional group in one molecule, the type of the compound may not be limited, 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, 7-amino-1-heptenethiol, etc., but cysteamine is preferably used.

[0073] In one embodiment of the present invention, 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, for example, 0.1 parts by weight or more, 1 parts 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, or 20 parts by weight or more, and may be included 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. It may be included in an amount of 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.

[0074] If the content of the above 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 including the binder for an all-solid-state battery according to the present invention may be reduced, thereby deteriorating the performance of the all-solid-state battery. If it exceeds 40 parts by weight, there is a concern that the binder with excessive polar functional group may remain in the electrode mixture layer, causing a side reaction with the electrode, for example, a sulfide-based solid electrolyte included in the positive electrode of the all-solid-state battery.

[0075]

[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 a binder composition that can be used in the manufacture of a positive electrode for an all-solid-state battery.

[0079] An all-solid-state battery binder composition 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.

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

[0081] Additionally, the binder composition may be in the form of a solution further containing a solvent.

[0082] The polymer including the repeating unit derived from the aromatic vinyl monomer and the repeating unit derived from the 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 thus a detailed description thereof will be omitted below. In addition, the solvent is the same as that described in the method for producing a binder for an all-solid-state battery described below, and thus a detailed description thereof will also be omitted.

[0083]

[0084] The above binder is formed by a crosslinked main chain by a compound containing two or more thiol functional groups when the reaction is initiated by the above initiator during the drying process in the manufacture of the positive electrode for an all-solid-state battery, and the main chain is formed by a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer and can be included in the positive electrode. At this time, the main chain may be formed by further including a polar functional group.

[0085]

[0086] In addition, since the binder composition forms a main chain including the repeating unit described above when the positive electrode is formed, the internal bonding strength with 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 can be further improved.

[0087]

[0088] <Method for manufacturing a binder for an all-solid-state battery>

[0089] Next, a method for manufacturing a binder for an all-solid-state battery is described.

[0090] For example, the binder for an all-solid-state battery according to the present invention can be manufactured 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 above-described 'binder composition for an all-solid-state battery'.

[0091] The polymer including the above aromatic vinyl monomer-derived repeating unit and the conjugated diene monomer-derived repeating unit is a portion that becomes a main chain after being manufactured as a binder, and the aromatic vinyl monomer-derived repeating unit and the conjugated diene monomer-derived repeating unit included in the polymer are the same as described above, so a detailed description thereof will be omitted below.

[0092] In the case of a compound containing two or more thiol functional groups and a compound capable of imparting a polar functional group, the polymer containing an aromatic vinyl monomer-derived repeating unit and a conjugated diene monomer-derived repeating unit that form the main chain of the binder can be connected to the main chain through a thiol-ene reaction via radical formation with an unsaturated double bond.

[0093] Compounds containing two or more thiol functional groups and compounds capable of imparting polar functional groups are also the same as those described above, so detailed description thereof will be omitted below.

[0094] The solvent is not limited in type as long as it does not react with a sulfide-based solid electrolyte, etc., and can disperse well a polymer including an aromatic vinyl monomer-derived repeating unit and a conjugated diene-based monomer-derived repeating unit, a compound including two or more thiol functional groups, and a compound capable of imparting a polar functional group without affecting the physical properties of the polymer, but for example, any one or a mixed solvent 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.

[0095] The above initiator may not be limited in type as long as it allows a radical reaction of an unsaturated double bond of a polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer and a compound including two or more thiol functional groups and a thiol group of a compound capable of providing a polar functional group to proceed.

[0096] At this time, in the mixed solution for manufacturing the binder for an all-solid-state battery, the content of the polymer including a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer relative to the solvent 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 manufacturing the binder for an all-solid-state battery according to the present invention may be excessive, which may unnecessarily delay the drying time during the manufacturing process, and if it exceeds 1 g / ml, the viscosity of the mixed solution may excessively increase, which may cause a problem in that a non-uniform reaction may occur in the mixed solution for manufacturing the binder for an all-solid-state battery.

[0097] Examples of the above initiator include persulfates such as potassium persulfate and ammonium persulfate; azo compounds such as 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-hydroxyethylpropionamide, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis(1-cyclohexanecarbonitrile); Examples of peroxides include methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, di-isopropyl peroxydicarbonate, and di-t-butyl peroxyisophthalate.

[0098]

[0099] <Cathode for all-solid-state batteries>

[0100] According to another aspect, an all-solid-state battery positive electrode is provided, comprising a binder for an all-solid-state battery according to the above-described embodiment of the present invention.

[0101] In one embodiment, the positive electrode for the all-solid-state battery may include the above-described binder for the all-solid-state battery, a conductive material, a positive electrode active material, and a solid electrolyte.

[0102] At this time, since the specific details of the binder for the all-solid-state battery are the same as those described above, a detailed description of the binder included in the positive electrode for the all-solid-state battery according to the present invention will be omitted in the following specification.

[0103] The above-mentioned all-solid-state battery binder may be included 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 entire all-solid-state battery positive electrode.

[0104] In addition to the binder for an all-solid-state battery according to the present invention, within the range satisfying the above content, 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 polymer binders may be further included.

[0105] The positive electrode active material included in the positive electrode for the above-mentioned all-solid-state battery is not particularly limited as long as it is a material capable of reversible absorption and release of lithium ions. For example, it may include at least one of a complex compound of metals such as cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0106] For a more specific example, as the core of the positive electrode active material, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b R b D2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b R b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α (In the above formula, 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 (In the above formula, 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 (in the above formula, 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 (In the above formula, 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 (In the above formula, 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 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G dO2 (in the above formula, 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 (in the above formula, 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 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (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.

[0107] 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; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0108] 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 a secondary particle formed by agglomeration of a plurality of particles.

[0109] The conductive material included in the positive electrode for the above-mentioned all-solid-state battery is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, it may include one or a mixture of two or more selected from the following conductive materials: graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black; conductive fibers such as carbon fibers or metal fibers such as VGCF (Vapor grown carbon fiber); metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0110] According to one embodiment of the present invention, the positive electrode for an all-solid-state battery may contain a conductive material in the range of 0 to 30 wt% based on 100 wt% of the positive electrode for an all-solid-state battery. According to specific embodiments of the present invention, the conductive material may be contained in the range of 0.5 wt% or more, 1 wt% or more, 3 wt% or more, or 5 wt% or more within the above range, and may also be contained in the range of 15 wt% or less, 10 wt% or less, 7 wt% or less, or 5 wt% or less. For example, the conductive material may be contained in the range of 0.5 to 5 wt% based on 100 wt% of the positive electrode for an all-solid-state battery. If the conductive material is contained in an amount exceeding the upper limit, the ratio of the active material is low, resulting in a decrease in energy density, and if the conductive material is contained in an amount less than the lower limit, the desired level of electronic conductivity is not achieved, resulting in a decrease in capacity development rate.

[0111] The solid electrolyte included in the positive electrode for the above-mentioned all-solid-state battery may be, for example, a sulfide-based solid electrolyte, and the sulfide-based solid electrolyte may be represented by the following chemical formula 1.

[0112] [Chemical Formula 1]

[0113] Li k M 2 l S m X 2 n

[0114] In the above chemical formula 1, 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, 2 is F, Cl, Br, I, Se, Te, or O, and 0 <k≤6, 0<l≤6, 0<m≤6 및 0≤n≤6이다.

[0115] For example, in the above chemical formula 1, M 2 can be B, Si, Ge, P or N.

[0116] For example, in the above chemical formula 1, X 2 can be F, Cl, Br, I or O.

[0117] For example, the sulfide-based solid electrolyte represented by the above chemical formula 1 is Li2S-P2S5, Li2S-P2S5-LiX, X is a halogen element, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n , 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 , may be one or more selected from 0≤x≤2.

[0118] In addition, preferably, the sulfide-based solid electrolyte may be an argyrodite-type solid electrolyte including at least one selected from among Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0119] A 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 side of the current collector, and the positive electrode active material layer may include the above-described binder, solid electrolyte, conductive material, and positive electrode active material.

[0120] The above positive electrode can be manufactured according to a method widely known in the art, and is not limited to a specific manufacturing method, but for example, the positive electrode active material, solid electrolyte, conductive material, binder, etc. can be mixed in a solvent to manufacture a positive electrode mixture in a slurry form, and the positive electrode mixture can be applied to a positive electrode current collector.

[0121] The above-described positive electrode current collector is generally made with a thickness of 3 to 500 ㎛. The positive electrode current collector is not particularly limited 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, silver, etc. can be used. The current collector can also form fine irregularities on its surface to increase the adhesiveness of the positive electrode active material, and various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric can be used.

[0122] In addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder, the positive electrode may further include additives such as fillers, coating agents, dispersants, and ion-conducting aids. The fillers, coating agents, dispersants, and ion-conducting aids may be known materials generally used in electrodes of all-solid-state secondary batteries.

[0123] The thickness of the above anode may be, for example, 70 to 150 μm.

[0124]

[0125] All-solid-state battery

[0126] Another embodiment 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 is the positive electrode for the all-solid-state battery described above.

[0127] The positive electrode included in the above all-solid-state battery has been described in detail above, so the negative electrode and solid electrolyte included in the all-solid-state battery will be described in detail below.

[0128] The solid electrolyte layer disposed between the positive and negative electrodes may include, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be the same as or different from the sulfide-based solid electrolyte included in the positive electrode.

[0129] For specific details on the sulfide-based solid electrolyte, refer to the positive electrode section described above.

[0130] 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 this range, pressurization and / or sintering of the solid electrolyte is more easily performed.

[0131] The solid electrolyte layer further includes, for example, a binder. The binder included in the solid electrolyte layer includes, but is not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like, and any binder used in the relevant technical field may be used. The binder of the solid electrolyte layer may be the same as or different from the binders of the positive active material layer and the negative active material layer.

[0132] Next, the negative electrode of the all-solid-state premise may include a negative electrode current collector and a negative electrode active material layer.

[0133] 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 ㎛ to 20 ㎛, 2 ㎛ to 10 ㎛, or 3 ㎛ to 7 ㎛. If the thickness of the negative electrode active material layer is too thin, lithium dendrites formed between the negative electrode active material layer and the negative electrode current collector 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 increases excessively, the energy density of the all-solid-state battery decreases and the internal resistance of the all-solid-state battery due to the negative electrode active material layer increases, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0134] The negative electrode active material layer includes, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0135] The negative active material included in the negative active material layer has, for example, a particle form. The average particle diameter of the negative active material having a particle form is, for example, 4 ㎛ or less, 3 ㎛ or less, 2 ㎛ or less, 1 ㎛ or less, or 900 nm or less. The average particle diameter of the negative active material having a particle form is, for example, 10 nm to 4 ㎛ or less, 10 nm to 3 ㎛ or less, 10 nm to 2 ㎛ or less, 10 nm to 1 ㎛ or less, or 10 nm to 900 nm or less. When the negative active material has an average particle diameter in this range, reversible absorption and / or desorption of lithium can be facilitated during charge and discharge. The average particle diameter of the negative active material is, for example, a volume-converted median diameter (D50) measured using a laser particle size distribution analyzer.

[0136] The negative electrode active material included in the negative electrode active material layer includes, for example, at least one selected from a carbon-based negative electrode active material and a metal or metalloid negative electrode active material.

[0137] The carbon-based negative electrode active material is, in particular, amorphous carbon. Amorphous carbon includes, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0138] The metal or metalloid negative electrode active material includes, but is not limited to, 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), and any metal or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used. For example, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0139] The negative electrode active material layer includes a type of negative electrode active material among these negative electrode active materials, or includes a mixture of a plurality of different negative electrode active materials. For example, the negative electrode active material layer includes only amorphous carbon, or 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). Alternatively, the negative electrode active material layer includes a mixture of amorphous carbon and 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). The mixing ratio of amorphous carbon and silver (Ag) etc. is a weight ratio, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to this range and is selected according to the required characteristics of the all-solid-state battery. When the negative active material has this composition, the cycle characteristics of the all-solid-state battery are further improved.

[0140] The negative active material included in the negative active material layer includes a mixture of first particles made of, for example, amorphous carbon and second particles made of a metal or a metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The metalloid is alternatively a semiconductor. 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. When the second particles have a content in this range, the cycle characteristics of, for example, an all-solid-state battery are further improved.

[0141] The negative active material layer includes, for example, a binder. The binder is, but is not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., and any binder used in the art may be used. The binder may be composed of a single binder or a plurality of different binders.

[0142] By including a binder in the negative active material layer, the negative active material layer is stabilized on the negative electrode current collector. Furthermore, cracking of the negative active material layer is suppressed despite changes in the volume and / or relative position of the negative active material layer during charge and discharge processes. For example, if the negative active material layer does not include a binder, it is possible for the negative active material layer to easily separate from the negative electrode current collector. The portion where the negative active material layer separates from the negative electrode current collector is exposed and comes into contact with the solid electrolyte layer, increasing the possibility of a short circuit. The negative active material layer is manufactured, for example, by applying a slurry containing dispersed materials for the negative electrode active material layer onto the negative electrode current collector and drying it. Incorporating a binder into the negative electrode active material layer enables stable dispersion of the negative active material in the slurry. For example, when applying the slurry onto the negative electrode current collector using a screen printing method, it is possible to suppress screen clogging (e.g., clogging by aggregates of the negative electrode active material).

[0143] The negative electrode current collector is composed of a material that does not react with lithium, i.e., does not form an alloy or compound. The material constituting the negative electrode current collector includes, but is not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that can be used as an electrode current collector in the relevant technical field may be used. The negative electrode current collector may be composed of one of the above-mentioned metals, or may be composed of an alloy or a coating material of two or more metals. The negative electrode current collector is, for example, in the form of a plate or foil.

[0144] The negative active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, dispersants, and ionic conductive agents.

[0145] An all-solid-state battery can be manufactured, for example, by manufacturing a positive electrode, a negative electrode, and a solid electrolyte layer separately and then laminating these layers.

[0146] The present invention provides a battery module including the above-described all-solid-state battery as a unit battery, a battery pack including the above-described battery module, and a device including the above-described battery pack as a power source.

[0147] At this time, specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0148] Below, specific embodiments of the present invention are presented. However, the embodiments described below are intended solely to specifically illustrate or explain the present invention and are not intended to limit the scope of the invention. Furthermore, any details not described herein are technically feasible to those skilled in the art and thus are omitted.

[0149]

[0150] Manufacturing Example 1: Manufacturing of binder and binder composition for all-solid-state batteries

[0151] (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 a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer to 9.5 g of p-xylene as a solvent, 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 is mixed at 30°C and atmospheric pressure for 12 hours at 300 rpm to prepare a mixed solution.

[0152] (2) The above mixed solution is pre-dried at 80°C and atmospheric pressure for 1 hour and then vacuum-dried at 80°C to produce a binder for an all-solid-state battery.

[0153] The above solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0154]

[0155] Manufacturing Example 2: Manufacturing of a binder and binder composition for an all-solid-state battery

[0156] (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), a polymer containing a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer, 0.135 g of 3-mercaptopropionic acid and 0.095 g of cysteamine as compounds capable of providing a polar functional group, and 0.03 g of trimethylolpropane tris (3-mercaptopropionate) (TMPMP), a compound containing two or more thiol functional groups, together with 0.01 g of 2,2-azobis (2-methylpropionitrile), a thermal initiator. The above solution is mixed at 30°C and atmospheric pressure for 12 hours at 300 rpm to prepare a mixed solution.

[0157] (2) The above mixed solution is pre-dried at 80°C and atmospheric pressure for 1 hour and then vacuum-dried at 80°C to produce a binder for an all-solid-state battery.

[0158] The above solution for preparing a binder for an all-solid-state battery corresponds to a binder composition.

[0159]

[0160] Comparative Manufacturing Example 1: Manufacturing of Binder and Binder Composition for All-Solid-State Battery

[0161] (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), a polymer containing a repeating unit derived from an aromatic vinyl monomer and a repeating unit 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.

[0162] (2) The above mixed solution is pre-dried at 80°C and atmospheric pressure for 1 hour and then vacuum-dried at 80°C to produce a binder for an all-solid-state battery.

[0163] The above solution for preparing a binder for an all-solid-state battery corresponds to a binder composition for an all-solid-state battery.

[0164]

[0165] Example 1: Preparation of a positive electrode for an all-solid-state battery

[0166] LiNi as 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 a binder composition prepared in Manufacturing Example 1 were mixed in a solvent at a weight ratio of 70:27.5:1:1.5 to prepare a cathode slurry, which was then applied to one surface of an aluminum current collector having a thickness of 15 ㎛, and pre-dried at 80°C and atmospheric pressure for 1 hour, and then dried at 80°C to prepare a cathode for an all-solid-state battery.

[0167]

[0168] Example 2: Preparation of a positive electrode for an all-solid-state battery

[0169] A positive electrode for an all-solid-state battery was manufactured in the same manner as in Example 1, except that the binder composition manufactured in Manufacturing Example 2 was used instead of the binder manufactured in Manufacturing Example 1.

[0170]

[0171] Comparative Example 1: Manufacturing of a positive electrode for an all-solid-state battery

[0172] A positive electrode for an all-solid-state battery was manufactured in the same manner as in Example 1, except that the binder composition manufactured in Comparative Manufacturing Example 1 was used instead of the binder manufactured in Manufacturing Example 1.

[0173]

[0174] Experimental Example 1: FT-IR Spectral Analysis

[0175] The FT-IR spectra of the binders for all-solid-state batteries according to the manufacturing examples and comparative manufacturing examples were measured using Fourier transform infrared spectroscopy (FT-IR), and the results are shown in Fig. 3.

[0176] Referring to Figure 3, it can be seen that the common spectrum appearing in all of Manufacturing Example 1, Manufacturing Example 2, and Comparative Manufacturing Example 1 is derived from SBR in a polymer state. In addition, 1740 cm -1 It can be seen that the crosslinking is formed due to the introduction of TMPMP as the spectrum around 1570 cm appears in both Manufacturing Examples 1 and 2. Finally, in the case of Manufacturing Example 2, -1 The appearance of the spectrum in the vicinity confirms that the two mixed polar functional groups, 3-mercaptopropionic acid and cysteamine, form hydrogen bonds, which gives the binder self-healing properties.

[0177]

[0178] Experimental Example 2: NMR Spectral Analysis

[0179] The NMR spectrum was measured for the binder formed inside the positive electrode for an all-solid-state battery according to Example 2 and Comparative Example 1, and the binder composition for an all-solid-state battery according to Comparative Manufacturing Example 1, using NMR (nuclear magnetic resonance spectroscopy), and the results are shown in Fig. 4.

[0180] Referring to FIG. 4, it can be seen that the common spectrum appearing in both Example 2 and Comparative Example 1 originates from the SBR in a polymer state according to Comparative Manufacturing Example 1. In addition, since the sizes of the peaks around 4.9 ppm and 5.5 ppm corresponding to vinyl groups are smaller in Example 2 than in Comparative Example 1, it can be confirmed that a polar functional group is introduced to the C=C double bond present in SBR in the binder formed inside the positive electrode after manufacturing the positive electrode for an all-solid-state battery according to the present invention.

[0181]

[0182] Experimental Example 3: Evaluation of Rate and Lifetime Characteristics of All-Solid-State Batteries

[0183] The rate characteristics and life characteristics were evaluated for all-solid-state batteries including the positive electrodes according to Examples 1 and 2 and Comparative Example 1.

[0184] The above all-solid-state battery was manufactured by the following method.

[0185] After loading 150 mg of Li6PS5Cl as a solid electrolyte into a mold cell, it is pelletized at a pressure of 70 MPa. The positive electrodes according to Examples 1 and 2 and Comparative Example 1 manufactured by the above process are loaded on one side of the solid electrolyte pellet, and Li is loaded on the other side. 0.5 An all-solid-state half-cell was fabricated by loading 100 mg of a composite cathode in which In and a solid electrolyte were mixed in a weight ratio of 8:2 and pressurizing at a pressure of 370 MPa. To analyze the performance of each electrode according to the operating pressure, the fastening strength of the bolts was adjusted so that the operating pressures of 70 MPa and 0.33 MPa were applied, respectively. To evaluate the all-solid-state half-cell, the cell was sealed to prevent atmospheric infiltration, and then transferred to a constant-temperature chamber to perform the electrochemical evaluation described below.

[0186] For the all-solid-state batteries including the positive electrodes according to Examples 1 and 2 and Comparative Example 1, the rate characteristics were evaluated by the following test method.

[0187] The rate characteristics were measured by charging and discharging five times each under current conditions of 0.1C - 0.2C - 0.5C - 0.7C - 1.0C - 0.2C at a driving voltage of 3.0 V to 4.3 V in CC mode at 30°C. The results are shown in Table 1 and Fig. 1 below.

[0188] For the all-solid-state battery including the positive electrode according to Example 1 and Comparative Example 1, the life characteristics were evaluated by the following test method.

[0189] The battery was charged at a rate (C-rate) of 0.1C until the voltage reached 4.3 V (vs. Li), and then cut-off at 4.3 V (vs. Li). Subsequently, the battery was discharged at a rate (C-rate) of 0.2C until the voltage reached 3.0 V (vs. Li) (1 st Cycle). The above charge / discharge test was repeated 50 cycles to measure the capacity retention rate of the discharge capacity, and the results are shown in Table 1 and Fig. 2 below.

[0190]

[0191] Driving pressure (MPa) Initial discharge capacity (mAh / g) Initial coulombic efficiency (%) 50 cycles Discharge capacity (mAh / g) Comparative example 10.33 146.57 3.49 0.1 Exemplary example 10.33 153.67 3.8 104.3 Exemplary example 20.33 151.57 4.1 110.2 Comparative example 170 173.97 9.7 - Exemplary example 170 175.18 0.0 - Exemplary example 270 174.07 9.7 -

[0192]

[0193] Referring to Table 1, Figures 1 and 2, it can be confirmed that the all-solid-state batteries including the positive electrodes according to Examples 1 and 2 have superior initial discharge capacity and initial coulombic efficiency compared to the all-solid-state battery including the positive electrode of Comparative Example 1 when the driving pressure is low (0 MPa). On the other hand, it can be confirmed that the difference in performance between the all-solid-state batteries including the positive electrodes according to Examples 1 and 2 and Comparative Example 1 is minimal when the driving pressure is high (70 MPa). This can be understood that the binder having 'self-healing properties' according to the present invention is effective in suppressing the interfacial delamination phenomenon between the active material and the solid electrolyte that occurs when the driving pressure is low. In addition, it can be seen that the all-solid-state battery including the positive electrode according to Example 2, which includes a binder in which the main chain of the binder is cross-linked by a compound including two or more thiol groups and in which a polar functional group is introduced into the main chain, has the best life characteristics.

[0194]

[0195] 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

Comprising a main chain cross-linked by a compound containing 1.2 or more thiol functional groups, The above main chain comprises a repeating unit derived from an aromatic vinyl monomer and a repeating unit derived from a conjugated diene monomer. Binder for all-solid-state batteries.

2. In paragraph 1, Compounds containing two or more thiol functional groups are 4,4'-biphenyldithiol (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. (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), At least one selected from the group consisting of tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC) and pentaerythritol tetrakis (3-mercaptobutylate). Binder for all-solid-state batteries.

3. In paragraph 1, The above 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. Binder for all-solid-state batteries.

4. In paragraph 1, The above 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. Binder for all-solid-state batteries.

5. In paragraph 1, The above main chain comprises 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. Binder for all-solid-state batteries.

6. In paragraph 1, The compound containing two or more thiol functional groups is included in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the main chain. Binder for all-solid-state batteries.

7. In paragraph 1, The above main chain further comprises a polar functional group, Binder for all-solid-state batteries.

8. In paragraph 7, The above 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. Binder for all-solid-state batteries.

9. In paragraph 7, The polar functional group is included in an amount of 0.1 to 40 parts by weight relative to 100 parts by weight of the main chain. Binder for all-solid-state batteries.

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. A binder composition for an all-solid-state battery.

11. In paragraph 10, The above all-solid-state battery binder further comprises a compound capable of imparting a polar functional group. A binder composition for an all-solid-state battery.

12. In paragraph 10, The above binder composition further comprises a solvent, A binder composition for an all-solid-state battery.

13. A binder, a conductive material, a positive electrode active material and a solid electrolyte according to Article 1. Cathode for all-solid-state batteries.

14. In Article 10, The above solid electrolytes are Li2S-P2S5, Li2S-P2S5-LiX (where X represents a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z. m S n (wherein m, 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, In), Li 7-x PS 6-x Cl x (But, 0≤x≤2), Li 7-x PS 6-x Br x (but, 0≤x≤2) and Li 7-x PS6-x I x (However, at least one of 0≤x≤2) is selected. Cathode for all-solid-state batteries.

15. In Article 10, The above solid electrolyte is an argyrodite-type solid electrolyte including at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I. Cathode for all-solid-state batteries.

16. A binder composition manufactured using the binder composition according to Article 10, Cathode for all-solid-state batteries.

17. Bipolar; cathode; and Comprising a solid electrolyte layer disposed between the positive and negative electrodes, The above positive electrode comprises the positive electrode for an all-solid-state battery according to claim 10 or claim 16. All-solid-state battery.

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