Composite solid electrolyte and preparation method thereof

Abstract

The invention relates to a composite solid electrolyte and a preparation method thereof. The composite solid electrolyte includes: a polymer including a PEO (polyethylene oxide)-based copolymer including a crosslinkable functional group; and a ceramic compound, in which at least a portion of the crosslinkable functional groups form cross-links with each other, such that the polymer forms a three-dimensional network structure, and in which the ceramic compound is contained in the three-dimensional network structure.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2022-0132767 filed on October 14, 2022, and Korean Patent Application No. 10-2023-0136065 filed on October 12, 2023, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety.

[0003] The present disclosure relates to a composite solid electrolyte and a method for preparing the same. [Background Technology]

[0004] Lithium-ion batteries using liquid electrolytes have a structure in which the negative electrode and the positive electrode are defined by a separator, so when the separator is damaged due to deformation or external impact, a short circuit may be caused, leading to risks such as overheating or explosion. Therefore, it can be said that the development of a solid electrolyte that ensures safety is a very important task in the field of lithium-ion secondary batteries.

[0005] The advantages of lithium secondary batteries using solid electrolytes are improved safety, prevention of electrolyte leakage to improve battery reliability, and ease of manufacturing thin batteries. In addition, lithium metal can be used as a negative electrode to improve energy density, so in addition to compact secondary batteries, it is expected to be applied to high-capacity secondary batteries for electric vehicles, and is therefore attracting attention as a next-generation battery.

[0006] Among solid electrolytes, a polymer solid electrolyte may include an ion conductive polymer material, and may be used in the form of a composite solid electrolyte in which the polymer material is mixed with an inorganic material.

[0007] This type of conventional hybrid (composite) solid electrolyte is prepared by dispersing inorganic powders (such as oxide ceramics) in a polymer matrix. It has the advantages of higher ignition and combustion stability than existing liquid electrolytes and higher ionic conductivity than polymer solid electrolytes, but it is difficult to meet basic prerequisites, such as improving the dispersibility of oxide ceramic particles in the polymer matrix and optimizing the physical properties of the polymer matrix used. In particular, when a highly crystalline polymer such as polyethylene oxide (PEO) is used as a matrix, there is a problem of difficulty in preparing a composite solid electrolyte with improved ionic conductivity. In other words, the high crystallinity of the PEO polymer hinders the mobility of the polymer chain, so the movement of lithium ions in the composite solid electrolyte is restricted, making it difficult to improve the ionic conductivity of the composite solid electrolyte.

[0008] In order to overcome the limitations of conventional composite solid electrolytes, attempts have been made to change the structure of crystalline polymers or add separate plasticizers to the polymers to improve the mobility of polymer chains and thus enhance the ionic conductivity of composite solid electrolytes. However, it is difficult to improve the ionic conductivity of composite solid electrolytes by simply changing the structure of the polymer or adding plasticizers.

[0009] Therefore, it is necessary to develop a technology that can improve the ionic conductivity of composite solid electrolytes by methods other than changing the polymer structure or adding plasticizers.

[0010] [Prior art literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Japanese Patent Application Publication No. 1994-124713 [Summary of the invention]

[0013] Technical issues

[0014] An object of the present disclosure is to provide a composite solid electrolyte and a method for preparing the same, which improves mechanical strength and ionic conductivity by uniformly dispersing a ceramic compound in a predetermined cross-linked polymer structure.

[0015] Another object of the present disclosure is to provide an all-solid-state battery containing a composite solid electrolyte having improved mechanical strength and ionic conductivity.

[0016] Technical Solution

[0017] According to one embodiment of the present disclosure, a composite solid electrolyte is provided, which includes: a polymer including a PEO (polyethylene oxide) type copolymer containing a cross-linkable functional group; and a ceramic compound, wherein at least a portion of the cross-linkable functional groups form cross-linked bonds with each other, so that the polymer forms a three-dimensional network structure, and wherein the ceramic compound is contained in the three-dimensional network structure.

[0018] The composite solid electrolyte may further include a cross-linking agent, and at least a portion of the cross-linkable functional groups of the PEO-based copolymer may form cross-linked bonds with each other through the cross-linking agent.

[0019] In addition, the crosslinkable functional group is bonded to the PEO-based copolymer through an alkylene linking group having 0 to 10 carbon atoms or an oxyalkylene linking group (wherein the alkylene linking group having 0 carbon atoms represents a single bond), and can be at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group.

[0020] Meanwhile, the composite solid electrolyte of one embodiment may further include a lithium salt dispersed on a polymer forming a three-dimensional network structure. Such a lithium salt may be included in a cation and anion state in which at least a portion thereof is dissociated. The cation and / or anion may exist in a state bound to a polymer chain and may move during the charge / discharge process of the battery.

[0021] In a specific embodiment, the PEO (polyethylene oxide)-based copolymer may be a copolymer containing repeating units of the following chemical formulas 1 to 3:

[0022] [Chemical formula 1]

[0023]

[0024] [Chemical formula 2]

[0025]

[0026] [Chemical formula 3]

[0027]

[0028] Wherein, in Chemical Formulas 1 to 3, R1 represents -CH2-O-(CH2-CH2-O) k -R3, wherein k is 0 to 20, and R3 represents an alkyl group having 1 to 5 carbon atoms,

[0029] R2 represents a substituent formed by bonding one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group to a polymer chain through an alkylene linking group having 0 to 10 carbon atoms or an oxyalkylene linking group (wherein an alkylene linking group having 0 carbon atoms represents a single bond), and

[0030] l, m and n are the number of repetitions of the repeating unit, wherein l and n are each independently an integer from 1 to 1000, and m is an integer from 0 to 1000.

[0031] In addition, in the composite solid electrolyte of one embodiment, the ceramic compound may include an oxide-based solid electrolyte selected from lithium metal oxides or lithium metal phosphates, and more specifically, may include at least one oxide-based solid electrolyte selected from the group consisting of lithium lanthanum zirconium oxide (LLZO) compounds, lithium silicon titanium phosphate (LSTP) compounds, lithium lanthanum titanium oxide (LLTO) compounds, lithium aluminum titanium phosphate (LATP) compounds, lithium aluminum germanium phosphate (LAGP) compounds and lithium lanthanum zirconium titanium oxide (LLZTO) compounds.

[0032] At the same time, according to another embodiment of the present disclosure, a method for preparing a composite solid electrolyte of an embodiment is provided, the method comprising the following steps: forming a mixture of a polyethylene oxide (PEO) type copolymer containing a cross-linkable functional group and a ceramic compound; and subjecting the PEO type copolymer contained in the mixture to a cross-linking reaction.

[0033] In the preparation method, the cross-linking reaction may be performed in the presence of at least one additive selected from the group consisting of a cross-linking agent and an initiator.

[0034] According to yet another embodiment of the present disclosure, there is provided an all-solid-state battery including an electrolyte layer including the composite solid electrolyte of one embodiment.

[0035] Beneficial Effects

[0036] The composite solid electrolyte of the present disclosure is capable of maintaining the inherent structural characteristics of the polymer without causing deformation or breakage of the polymer chain, and the ceramic compound is uniformly dispersed within the composite solid electrolyte, thereby exhibiting improved mechanical properties and ionic conductivity. [Specific implementation method]

[0037] Hereinafter, for a better understanding of the present disclosure, specific embodiments will be described in more detail.

[0038] The terms or words used in the specification and the appended claims should not be interpreted as limited to the ordinary meaning or dictionary meaning, and based on the principle that the inventor can appropriately define the concept of the term in order to appropriately describe his own invention in the best manner, the present disclosure should be interpreted as having meanings and concepts consistent with the technical ideas of the present disclosure.

[0039] As used herein, the term "three-dimensional network structure" is a structure comprising a three-dimensional framework and an internal space formed by the framework, wherein the framework may comprise polymer chains, and the polymer chains comprise cross-links formed by cross-linkable functional groups, such as cross-links between cross-linkable functional groups and / or cross-links between cross-linkable functional groups and cross-linking agents. The three-dimensional network structure may also be referred to as a cross-linked structure.

[0040] Meanwhile, conventionally, in order to improve the ionic conductivity of solid electrolytes, composite solid electrolytes are prepared by mixing a polymer matrix with a ceramic compound (e.g., oxide). However, a problem with such composite solid electrolytes is that the ionic conductivity decreases when the oxide-based ceramic particles in the polymer matrix are unevenly distributed or when a highly crystalline polymer such as polyethylene oxide is used as a polymer.

[0041] Therefore, the present inventors have prepared a polymer in which a PEO (polyethylene oxide) type copolymer modified with a cross-linkable functional group is cross-linked, wherein the PEO type copolymer and a ceramic compound are mixed and then cross-linking is induced during a coating and drying process to prepare a composite solid electrolyte containing a polymer in which the ceramic compound is uniformly dispersed between polymer chains.

[0042] As a result, the present inventors confirmed that it is possible to provide a composite solid electrolyte showing improved mechanical properties and ion conductivity compared with existing composite solid electrolytes, and completed the present invention.

[0043] Hereinafter, a composite solid electrolyte according to one embodiment will be described in detail.

[0044] Composite solid electrolyte

[0045] A composite solid electrolyte according to one embodiment of the present disclosure comprises:

[0046] A polymer comprising a PEO (polyethylene oxide) type copolymer containing crosslinkable functional groups; and a ceramic compound, wherein at least a portion of the crosslinkable functional groups form crosslinks with each other, so that the polymer forms a three-dimensional network structure, and wherein the ceramic compound is contained in the three-dimensional network structure.

[0047] Such a composite solid electrolyte may include a three-dimensional network structure due to the cross-linked structure of the polymer. The three-dimensional network structure is a structure including a three-dimensional framework and an internal space between the frameworks, wherein the framework may include a polymer chain containing a cross-linked bond formed by a cross-linkable functional group, and a ceramic compound may be included in the internal space.

[0048] The crosslinked bonds formed by the crosslinkable functional groups forming the framework may include crosslinked bonds between the crosslinkable functional groups and / or crosslinked bonds between the crosslinkable functional groups and the crosslinking agent. When the composite solid electrolyte further includes a crosslinking agent, at least a portion of the crosslinkable functional groups may form crosslinked bonds with each other through the crosslinking agent.

[0049] The ceramic compound is contained in the internal space of the three-dimensional network structure in a dispersed form, so that the ceramic compound can be uniformly dispersed. Due to the morphological characteristics of the uniform dispersion of the ceramic compound, the mechanical strength and ionic conductivity of the composite solid electrolyte can be further improved.

[0050] In other words, part of the polymer chains forming cross-links can act as a plasticizer to ensure flexibility, thereby reducing crystallinity, which has been a long-standing problem with PEO. In addition, part of the polymer chains forming cross-links acts as a cross-linking agent, making it possible to disperse the ceramic compound more uniformly by forming a three-dimensional grid structure.

[0051] Meanwhile, in the PEO-based copolymers, the crosslinkable functional groups contained in the PEO-based copolymers can be directly bonded to the main chain of the PEO-based copolymers, but can also be bonded through an alkylene linking group or an oxyalkylene linking group. Therefore, the crosslinkable functional groups can be bonded through an alkylene linking group or an oxyalkylene linking group with 0 to 10 carbon atoms (wherein the alkylene linking group with 0 carbon atoms represents a single bond), and can be selected from at least one of the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group.

[0052] In one embodiment of the present disclosure, the crosslinkable functional group may be composed of two or more types. The crosslinkable functional groups may be the same or different from each other, preferably different. When the crosslinkable functional groups are different, multiple types of repeating units containing these functional groups may be included. In addition, when multiple types of crosslinkable functional groups are included, it may be easier to control the mobility and ionic conductivity of the polymer chain.

[0053] The crosslinkable functional group refers to a functional group that can form a crosslink bond between crosslinkable functional groups and / or form a crosslink bond with each other through a crosslinking agent, and can be bonded to the main chain of the polymer chain in the form of a side chain.

[0054] In a more specific example, the PEO-based copolymer containing a cross-linkable functional group may be a copolymer containing repeating units of the following Chemical Formulas 1 to 3:

[0055] [Chemical formula 1]

[0056]

[0057] [Chemical formula 2]

[0058]

[0059] [Chemical formula 3]

[0060]

[0061] Wherein, in Chemical Formulas 1 to 3, R1 represents -CH2-O-(CH2-CH2-O) k -R3, wherein k is 0 to 20, and R3 represents an alkyl group having 1 to 5 carbon atoms,

[0062] R2 represents a substituent formed by bonding one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group to a polymer chain through an alkylene linking group having 0 to 10 carbon atoms or an oxyalkylene linking group (wherein an alkylene linking group having 0 carbon atoms represents a single bond), and

[0063] l, m and n are the number of repetitions of the repeating unit, wherein l and n are each independently an integer from 1 to 1000, and m is an integer from 0 to 1000.

[0064] For example, the cross-linkable functional group of R2 can form a polymer in the form of a matrix having a three-dimensional network structure formed by cross-linking bonds. By forming a three-dimensional network structure by cross-linking bonds, the mechanical properties of the polymer solid electrolyte can be improved, and the ceramic compound can be uniformly dispersed in this three-dimensional network structure to provide a composite solid electrolyte of one embodiment with more improved ionic conductivity.

[0065] In addition, it is apparent that the PEO-based copolymer includes two or more types of repeating units of Chemical Formula 3, wherein R2 is a cross-linkable functional group different from each other, and also includes one or more types of repeating units of Chemical Formula 2.

[0066] When l, m and n are all less than 1, it is difficult to form a polymer due to the small molecular weight, and when l, m and n are all greater than 1000, the solubility during the preparation of the mixed solution decreases due to the increase in viscosity, and the molding for preparing the solid electrolyte may become difficult. In particular, when the number of repetitions of the repeating unit containing a crosslinkable functional group in l, m and n is greater than 1000, the degree of crosslinking increases excessively, the mobility of the polymer chain may decrease, and the ionic conductivity of the solid electrolyte may decrease.

[0067] As used herein, "hydroxy" refers to an -OH group.

[0068] As used herein, "carboxyl" refers to a -COOH group.

[0069] As used herein, "isocyanate" refers to a -N=C=O group.

[0070] As used herein, "nitro" refers to a -NO2 group.

[0071] As used herein, "cyano" refers to a -CN group.

[0072] As used herein, "amide" refers to -C(=O)NR'R", wherein R' and R" can each independently be hydrogen or C1 to C5 alkyl, or R' and R" together with the N atom to which they are attached form a heterocycle having 4 to 8 carbon atoms in the ring structure.

[0073] As used herein, "amino" may be selected from the group consisting of monoalkylamino, monoarylamino, monoheteroarylamino, dialkylamino, diarylamino, diheteroarylamino, alkylarylamino, alkylheteroarylamino, arylheteroarylamino, and the carbon number thereof is not particularly limited, but is preferably 1 to 30. Specific examples of amine include methylamino, dimethylamino, ethylamino, diethylamino, phenylamino, naphthylamino, biphenylamino, dibiphenylamino, anthracenylamino, 9-methyl-anthrylamino, diphenylamino, phenylnaphthylamino, ditolylamino, phenyltolylamino, triphenylamino, biphenylnaphthylamino, phenylbiphenylamino, biphenylfluorenylamino, phenyltriphenyleneamino, and biphenyltriphenyleneamino, but are not limited thereto. In addition, "amino" refers to -NH2.

[0074] As used herein, "allyl" refers to a -CH2-CH=CH2 group.

[0075] The weight average molecular weight (Mw) of the copolymer containing chemical formula 1 to 3 can be 100000g / mol to 2000000g / mol, specifically can be 100000g / mol or more, 200000g / mol or more, or 300000g / mol or more, and 1600000g / mol or less, 1800000g / mol or less, or 2000000g / mol or less. If the weight average molecular weight (Mw) of the copolymer is less than 100000g / mol, the mechanical properties of the solid electrolyte to be prepared may not be met. If the weight average molecular weight (Mw) of the copolymer is greater than 2000000g / mol, during the preparation of the mixed solution, the solubility is reduced due to the increase in viscosity, and the molding for preparing the solid electrolyte can become difficult. In addition, due to the increase in crystallinity and the reduction in the internal chain mobility of the solid electrolyte, the ionic conductivity of the composite solid electrolyte can be reduced.

[0076] In particular, when the repetition number of the repeating unit of Chemical Formula 3 containing a crosslinkable functional group in l, m, and n is greater than 1000, the degree of crosslinking excessively increases and the mobility of polymer chains decreases, which may result in a decrease in ionic conductivity of the solid electrolyte.

[0077] Furthermore, the copolymer may be a random copolymer or a block copolymer.

[0078] In one embodiment of the present disclosure, the composite solid electrolyte may include crosslinks between crosslinkable functional groups. In addition, the composite solid electrolyte may also include a crosslinking agent, so that at least a portion of the crosslinkable functional groups form crosslinks with each other through the crosslinking agent. Therefore, it may further include a crosslinking agent and a crosslinking bond between the crosslinkable functional groups.

[0079] The crosslinking bonds between the crosslinkable functional groups may be urethane crosslinking bonds, ester crosslinking bonds, hydrogen bonds, bonds formed by free radical polymerization of vinyl groups at the ends of allyl groups (-CH2-CH=CH2), etc., but are not limited to these examples.

[0080] In addition, when a crosslinking agent is added during the preparation of the composite solid electrolyte, a crosslinking bond can be formed between the crosslinking agent and the crosslinkable functional group. The crosslinking bond can be a hydrogen bond, a bond formed by Lewis acid-base interaction, an ionic bond, a coordination bond, or a bond formed by free radical polymerization.

[0081] The crosslinking agent is not particularly limited as long as it is a multifunctional crosslinking agent capable of forming a crosslink bond with a crosslinkable functional group. For example, the crosslinking agent can be selected from trimethylolpropane trimethacrylate, poly(ethylene glycol) diacrylate, poly(ethylene glycol) dimethacrylate, ethylene glycol dimethacrylate (hereinafter referred to as "EGDMA"), 1,3-diisopropenylbenzene (DIP), 1,4-diacrylpiperazine, 2-(diethylamino)ethyl methacrylate, 2,6-bisacrylaminopyridine, 3-(acryloyloxy)-2-hydroxypropyl methacrylate, 3,5-bis(acryloylamino)benzoic acid, 3-aminopropyl triethoxysilane, 3-isocyanatopropyl triethoxysilane, 3-methacryloxypropyl trimethoxysilane, bis-(1- One or more polyfunctional crosslinking agents selected from the group consisting of (tert-butylperoxy)-1-methylethyl)-benzene, dicumyl peroxide, dimethacrylate, divinylbenzene, malein glycol acrylate, glycidyl methacrylate, hydroxyquinoline, i-phenyldiethoxysilane, malein glycol acrylate, methylenebisacrylamide, N,N'-1,4-phenylenedipropyleneamine, N,O-bisacryloyl-phenylalaninol, N,O-bismethacryloylethanolamine, pentaerythritol triacrylate, phenyltrimethoxysilane, tetramethoxysilane, tetramethylene compounds, tetraethoxysilane and triallyl isocyanurate, for example, polyvalent compounds having two or more functionalities.

[0082] In addition, the content of the crosslinking agent may be 1 to 30 parts by weight based on 100 parts by weight of the PEO-based copolymer containing a crosslinkable functional group. If the content of the crosslinking agent is less than 1 part by weight, crosslinking with the crosslinkable functional group cannot be fully achieved, and if the content of the crosslinking agent is greater than 30 parts by weight, excessive crosslinking occurs and the mobility of the polymer chain decreases, which may result in reduced ionic conductivity.

[0083] In one embodiment of the present disclosure, the composite solid electrolyte may further include a lithium salt. The lithium salt is contained in the internal space between the polymer chains in a dissociated ionic state, thereby being able to improve the ionic conductivity of the composite solid electrolyte. At least a portion of the cations and / or anions dissociated from the lithium salt exist in a state bound to the polymer chain and can exhibit mobility during charge / discharge of the battery.

[0084] The lithium salt may include at least one selected from the group consisting of: (CF3SO2)2NLi (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI), (FSO2)2NLi (lithium bis(fluorosulfonyl)imide, LiFSI), LiNO3, LiOH, LiCl, LiBr, LiI, LiClO4, LiBF4, LiB 10 Cl 10 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, LiC(CF3SO2)3, lithium chloroborane, lithium lower aliphatic carboxylate and lithium tetraphenylborate.

[0085] In addition, based on 100 parts by weight of the PEO-based copolymer containing a crosslinkable functional group, the content of the lithium salt may be 25 parts by weight to 45 parts by weight. Specifically, the content may be more than 25 parts by weight, more than 30 parts by weight, or more than 35 parts by weight, or less than 40 parts by weight or less than 45 parts by weight. If the content of the lithium salt is less than 25 parts by weight, the ionic conductivity of the composite solid electrolyte may be reduced, and if the content of the lithium salt exceeds 45 parts by weight, the mechanical strength may be reduced.

[0086] In one embodiment of the present disclosure, the composite solid electrolyte may include a ceramic compound. The ceramic compound has a lithium ion transport capability to improve lithium ion conductivity, preferably contains lithium atoms but does not store lithium, and has the function of transporting lithium ions, which can improve the ion conductivity of the composite solid electrolyte.

[0087] In addition, the ceramic compound can be contained between the cross-linked polymer chains in a uniformly dispersed state, for example, within a three-dimensional network structure. The ceramic compound is added during the cross-linking process and can be uniformly dispersed between the cross-linked polymer chains without aggregation. Due to its uniform dispersion form, this ceramic compound is advantageous in improving the mechanical strength and ionic conductivity of the composite solid electrolyte.

[0088] In addition, the ceramic compound may be in particle form. Due to the morphological characteristics of the particles, they can be included in the composite solid electrolyte in a more uniformly dispersed state. The particles of the ceramic compound may be spherical, and their diameter may be 100 nm to 1000 nm. If the diameter is less than 100 nm, the non-crystallization effect caused by the reduction of the polymer crystallinity may be slight, and if the diameter is greater than 1000 nm, the dispersion is reduced due to the increase in aggregation between the particles, which may lead to difficulty in uniform dispersion.

[0089] The ceramic compound may be an oxide or phosphate compound, such as an oxide solid electrolyte in the form of lithium metal oxide or lithium metal phosphate. More specifically, the ceramic compound may be at least one selected from the group consisting of: garnet-type lithium lanthanum zirconium oxide (LLZO, Li7La3Zr2O 12 ) compounds, perovskite-type lithium lanthanum titanium oxide (LLTO, Li3xLa 2 / 3-x TiO3) compounds, phosphate NASICON type lithium aluminum titanium phosphate (LATP, Li 1+x Al x Ti 2-x (PO4)3) compounds, lithium aluminum germanium phosphate (LAGP, Li 1.5 Al 0.5 Ge 1.5 (PO4)3) compounds, lithium silicon titanium phosphate (LSTP, LiSiO2TiO2(PO4)3) compounds and lithium lanthanum zirconium titanium oxide (LLZTO) compounds. More preferably, at least one oxide solid electrolyte selected from the group consisting of lithium lanthanum zirconium oxide (LLZO), lithium silicon titanium phosphate (LSTP), lithium lanthanum titanium oxide (LLTO), lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP) and lithium lanthanum zirconium titanium oxide (LLZTO) can be used.

[0090] Oxide or phosphate oxide solid electrolytes usually have ionic conductivity values ​​of up to 10 at room temperature. -4 S / cm to 10 -3 S / cm, which has the advantages of being stable in the high voltage region and stable in air, and thus easy to synthesize and handle.

[0091] In addition, even at high temperatures above 400°C, ceramic compounds are not prone to combustion or ignition, and therefore have high high temperature stability. Therefore, when the composite solid electrolyte contains a ceramic compound, it can not only improve the mechanical strength of the composite solid electrolyte, but also improve the high temperature stability and ionic conductivity of the composite solid electrolyte.

[0092] The ceramic compound may be included in an amount of 10 to 100 parts by weight, or 10 to 60 parts by weight, based on 100 parts by weight of the PEO-based copolymer containing a cross-linkable functional group.

[0093] If the content of the ceramic compound is too low, the effect of reducing the crystallinity of the polymer and making it amorphous due to the ceramic compound is reduced, so that the effect of increasing the ionic conductivity of the composite solid electrolyte is not significant, and due to the formation of a composite material, the mechanical properties cannot reach the expected level.

[0094] If the content of the ceramic compound is too much, the ceramic compound cannot be uniformly dispersed in the polymer, and a phenomenon occurs in which particles of the ceramic compound agglomerate and aggregate with each other, thereby being able to prepare a composite solid electrolyte having reduced ion conductivity.

[0095] Preparation method of composite solid electrolyte

[0096] A method for preparing a composite solid electrolyte according to another embodiment of the present disclosure may include the steps of: forming a mixture of a polyethylene oxide (PEO)-based copolymer containing a crosslinkable functional group and a ceramic compound; and subjecting the PEO-based copolymer contained in the mixture to a crosslinking reaction.

[0097] In this preparation method, the PEO-based copolymer containing a cross-linkable functional group has been described above, and thus further description thereof will be omitted.

[0098] In one embodiment of the present disclosure, the cross-linking reaction step may be performed in the presence of at least one additive of a cross-linking agent and an initiator.

[0099] Furthermore, the lithium salt may be added together in the mixing step or the cross-linking reaction step.

[0100] Furthermore, the ceramic compound may be the same as that used in the above-mentioned composite solid electrolyte, and may be used in a similar content.

[0101] The cross-linking bond may be formed in the process of coating a mixed solution containing a PEO-based copolymer on a substrate to form a coating film and then drying the coating film.

[0102] Specifically, the mixed solution may be prepared by mixing the PEO-based copolymer in a solvent, and further, the solution may be prepared by mixing and dissolving a cross-linking agent, an initiator, and / or a lithium salt together.

[0103] The solvent is not particularly limited as long as it can be mixed and dissolved with the PEO-based copolymer, crosslinking agent, initiator and / or lithium salt, and can be easily removed by a drying process. For example, the solvent can be acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropanol, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), etc.

[0104] Considering the degree that the forming process for preparing composite solid electrolyte can be carried out smoothly, the concentration of mixed solution can be appropriately adjusted. Specifically, the concentration of mixed solution can refer to the concentration (weight %) of PEO-type copolymer in mixed solution. The concentration of mixed solution can be 5 weight % to 20 weight %, specifically, can be more than 5 weight %, more than 7 weight % or more than 9 weight % and less than 13 weight %, less than 17 weight % or less than 20 weight %. If the concentration of mixed solution is less than 5 weight %, the concentration can be too diluted, and the mechanical strength of composite solid electrolyte can be reduced, or can flow downward when coated on substrate. If the concentration of mixed solution is greater than 20 weight %, it is difficult to dissolve the lithium salt of desired concentration in mixed solution, and viscosity is high, so solubility can be reduced, or it is difficult to be coated in the form of uniform film.

[0105] The substrate is not particularly limited as long as it can be used as a carrier for coating. For example, the substrate can be SUS (stainless steel), polyethylene terephthalate film, polytetrafluoroethylene film, polyethylene film, polypropylene film, polybutylene film, polybutadiene film, vinyl chloride copolymer film, polyurethane film, ethylene-vinyl acetate film, ethylene-propylene copolymer film, ethylene-ethyl acrylate copolymer film, ethylene-methyl acrylate copolymer film or polyimide film.

[0106] In addition, the coating method is not particularly limited as long as it can form a coating film by coating the mixed solution on the substrate. For example, the coating method may be a rod coating method, a roller coating method, a spin coating method, a slit coating method, a die coating method, a blade coating method, a comma coating method, a slot die coating method, a lip coating method, a spray coating method or a solution casting method.

[0107] The coating film formed on the substrate by the above-mentioned coating method can be formed into a solid electrolyte membrane, wherein the residual solvent is completely removed by a drying process. Drying can be carried out in a primary drying process and a secondary drying process, respectively, to prevent the membrane from shrinking due to rapid evaporation of the solvent. The first drying process can remove part of the solvent by room temperature drying, and the second drying process can completely remove the solvent by vacuum high temperature drying. High temperature drying can be carried out at a temperature of 80°C to 130°C. If the high temperature drying temperature is lower than 80°C, the residual solvent cannot be completely removed, and if the high temperature drying temperature is higher than 130°C, the membrane shrinks, making it difficult to form a uniform electrolyte membrane.

[0108] In addition, the crosslinking agent may form a bond with the crosslinkable functional group. Details of the type of the crosslinking agent, the content of the crosslinking agent, and the type of bond with the crosslinkable functional group are the same as described above.

[0109] In addition, the initiator can induce a free radical polymerization reaction between the crosslinkable functional groups, thereby forming a crosslinking bond between the crosslinkable functional groups. The functional group capable of free radical polymerization may be a functional group containing a vinyl group at the terminal, such as an allyl group.

[0110] The initiator is not particularly limited as long as it is an initiator capable of inducing a free radical polymerization reaction between crosslinkable functional groups. For example, the initiator may include at least one selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, cumene hydroperoxide, diisopropylphenyl-hydroperoxide, tert-butyl hydroperoxide, p-methane hydroperoxide and 2,2'-azobis(2-methylpropionitrile).

[0111] Based on 100 parts by weight of the PEO-based copolymer containing a crosslinkable functional group, the amount of the initiator can be 0.5 parts by weight to 2 parts by weight. When the initiator is used within the above range, a free radical polymerization reaction between the crosslinkable functional groups can be induced, and a crosslink bond can be effectively formed.

[0112] In addition, the details of the content and type of the lithium salt are the same as described above.

[0113] Through the above preparation method, a composite solid electrolyte according to an embodiment can be prepared, in which the ceramic compound is uniformly dispersed between the cross-linked polymer chains.

[0114] All-solid-state battery

[0115] Another embodiment of the present disclosure also relates to an all-solid-state battery comprising the above-mentioned composite solid electrolyte, wherein the all-solid-state battery comprises a negative electrode, a positive electrode and a composite solid electrolyte arranged between the negative electrode and the positive electrode, and the composite solid electrolyte is prepared according to the above-mentioned one embodiment.

[0116] Specifically, the composite solid electrolyte comprises a polymer cross-linked with a PEO (polyethylene oxide) type copolymer containing a cross-linkable functional group and a ceramic compound, and the ceramic compound is uniformly dispersed in the three-dimensional network structure of the polymer, thereby improving the ionic conductivity, and is therefore suitable as an electrolyte for an all-solid-state battery.

[0117] Meanwhile, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, wherein the positive electrode active material layer may be formed on one surface of a positive electrode current collector.

[0118] The positive electrode active material layer contains a positive electrode active material, a binder, and a conductive material.

[0119] In addition, the positive electrode active material is not particularly limited as long as it is a material that can reversibly absorb and desorb lithium ions, and examples thereof may be layered compounds such as lithium cobalt oxide, lithium nickel oxide, Li[Ni x Co y Mn z M v ]O2 (wherein M is any one or two or more elements selected from the group consisting of Al, Ga and In; and 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, and x+y+z+v=1), Li(Li a M b-a-b' M' b' ) 2-c A c (wherein 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, and 0≤c≤0.2; M includes Mn and at least one selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B; and A is at least one selected from the group consisting of P, F, S and N), or a compound substituted with at least one transition metal; lithium manganese oxide, such as a chemical formula Li 1+y Mn 2-y O4 (where y ranges from 0 to 0.33), LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, and Cu2V2O7; 1-y M y Ni-type lithium nickel oxide represented by O2 (wherein M is Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is in the range of 0.01 to 0.3); 2-y M y Lithium manganese composite oxide represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y ranges from 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4, in which part of Li is replaced by alkaline earth metal ions, disulfide, and composite oxide formed by Fe2(MoO4)3, but not limited to these.

[0120] In addition, based on the total weight of the positive electrode active material layer, the content of the positive electrode active material may be 40% to 80% by weight. Specifically, the content of the positive electrode active material may be 40% by weight or more or 50% by weight or more, and 70% by weight or less or 80% by weight or less. If the content of the positive electrode active material is less than 40% by weight, the connectivity and electrical properties between the positive electrode active materials are insufficient, and if the content of the positive electrode active material is greater than 80% by weight, the mass transfer resistance may increase.

[0121] The binder is a component that facilitates bonding between the positive electrode active material and the conductive material and with the current collector. The binder may include at least one selected from the group consisting of styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinyl pyrrolidone, polyvinyl pyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride and poly(vinylidene fluoride)-hexafluoropropylene. Preferably, the binder may include at least one selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethyl cellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0122] In addition, based on the total weight of the positive electrode active material layer, the content of the binder may be 1 wt % to 30 wt %. Specifically, the content of the binder may be 1 wt % or more or 3 wt % or more, and 15 wt % or less or 30 wt % or less. If the content of the binder is less than 1 wt %, the adhesion between the positive electrode active material and the positive electrode current collector is reduced, and if the content of the binder is greater than 30 wt %, the adhesion is improved, but the content of the positive electrode active material is also reduced accordingly, which can reduce the battery capacity.

[0123] In addition, the conductive material is not particularly limited as long as it does not cause side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery and has excellent conductivity. The conductive material can generally be graphite or conductive carbon, and can be, for example, but not limited to, one selected from the group consisting of: graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black and summer black; carbon materials with a crystal structure of graphene or graphite; conductive fibers, such as carbon fibers and metal fibers; fluorocarbons; metal powders, such as aluminum powder and nickel powder; conductive whiskers, such as zinc oxide and potassium titanate; conductive oxides, such as titanium oxide; conductive polymers, such as polyphenylene derivatives; and mixtures of two or more thereof.

[0124] Based on the total weight of the positive electrode active material layer, the content of the conductive material can generally be 0.5 wt % to 30 wt %. Specifically, the content of the conductive material can be more than 0.5 wt % or more than 1 wt %, and less than 20 wt % or less than 30 wt %. If the content of the conductive material is too low, i.e., less than 0.5 wt %, it is difficult to achieve the effect of improving conductivity, or the electrochemical characteristics of the battery may deteriorate. If the content of the conductive material is too high, i.e., more than 30 wt %, the amount of the positive electrode active material is relatively small, so the capacity and energy density can be reduced. There is no particular limitation on the method of incorporating the conductive material into the positive electrode, and conventional methods known in the prior art can be used, such as coating on the positive electrode active material.

[0125] In addition, the positive electrode current collector supports the positive electrode active material layer and plays a role in transferring electrons between the external wire and the positive electrode active material layer.

[0126] There is no particular limitation on the positive electrode current collector, as long as it does not cause chemical changes in the all-solid-state battery and has high conductivity. For example, the positive electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, palladium, fired carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc.

[0127] The positive electrode current collector may have fine protrusions and depressions on its surface, or may adopt a three-dimensional porous structure to improve the bonding strength with the positive electrode active material layer. Therefore, the positive electrode current collector may be used in any of various forms, including films, sheets, foils, grids, nets, porous bodies, foams, and non-woven fabric structures.

[0128] The above-mentioned positive electrode can be prepared according to a conventional method. Specifically, the positive electrode can be prepared by the following process, wherein a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a conductive material and a binder in an organic solvent is coated on a positive electrode collector and dried, and, optionally, compression molding is performed on the collector to improve the electrode density. At this time, as an organic solvent, it is preferred to use a solvent that can evenly disperse the positive electrode active material, the binder and the conductive material and is easily volatile. Specifically, acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropanol, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), etc. can be mentioned.

[0129] On the other hand, the negative electrode included in the all-solid-state battery contains a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of a negative electrode current collector.

[0130] The negative electrode active material may include a material capable of reversibly inserting and deinserting lithium (Li + ) that can react with lithium ions to reversibly form a lithium-containing compound material, lithium metal or a lithium alloy.

[0131] Able to reversibly insert and deintercalate lithium ions (Li + ) can be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + ) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitrate or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) and a metal selected from sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al) and tin (Sn).

[0132] Preferably, the negative electrode active material may be lithium metal, specifically, may be in the form of a lithium metal film or lithium metal powder.

[0133] Based on the total weight of the negative electrode active material layer, the content of the negative electrode active material may be 40% to 80% by weight. Specifically, the content of the negative electrode active material may be 40% by weight or more or 50% by weight or more, and 70% by weight or less or 80% by weight or less. If the content of the negative electrode active material is less than 40% by weight, the electrical performance may be insufficient, and if the content of the negative electrode active material is greater than 80% by weight, the mass transfer resistance may increase.

[0134] In addition, the binder is the same as the binder used for the positive electrode active material layer described above.

[0135] In addition, the conductive material is the same as the conductive material used for the positive electrode active material layer described above.

[0136] In addition, the negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the corresponding battery and has conductivity. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. In addition, similar to the positive electrode current collector, the negative electrode current collector can be used in various forms, such as a film, sheet, foil, net, porous body, foam, and non-woven fabric structure having fine protrusions and depressions formed on its surface.

[0137] The preparation method of the negative electrode is not particularly limited, and can be prepared by forming a negative electrode active material layer on the negative electrode current collector using a layer or film formation method commonly used in the art. For example, methods such as compression, coating and deposition can be used. In addition, the negative electrode of the present disclosure also includes a case where the battery is assembled in a state where there is no lithium film on the negative electrode current collector, and then a metal lithium film is formed on the metal plate by initial charging.

[0138] According to yet another embodiment, a battery pack including the all-solid-state battery as a unit cell, a battery pack including the battery pack, and a device including the battery pack as a power source are provided.

[0139] Herein, specific examples of the device may include, but are not limited to: power tools driven by motors; electric vehicles, including electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), etc.; electric two-wheeled vehicles, including electric bicycles (E-bike) and electric scooters (E-scooters); electric golf carts; power storage systems, etc.

[0140] Preferred embodiments will be given below to facilitate understanding of the present invention. However, the following embodiments are only for illustrative purposes, and the scope of the present invention is not limited thereto.

[0141] Example

[0142] Example 1: Preparation of composite solid electrolyte

[0143] Step 1) Preparation of polymer containing copolymer

[0144] A polyethylene oxide (PEO) copolymer of the following chemical formula 1a was prepared:

[0145] [Chemical formula 1a]

[0146]

[0147] Wherein, in chemical formula 1a, R1 is -CH2-O-(CH2-CH2-O) k-CH3, R2 is -CH2-O-CH2-CH=CH2, k is 2, the ratio of l:m:n is 85:13:2, and the weight average molecular weight of the copolymer is about 2000000 g / mol.

[0148] The copolymer of Chemical Formula 1a has an allyl group as a crosslinkable functional group bonded via an oxymethylene linker.

[0149] The polyethylene oxide copolymer is mixed with acetonitrile as a solvent, trimethylolpropane trimethacrylate as a crosslinking agent, benzoyl peroxide as an initiator, LiTFSI as a lithium salt, and LSTP as a ceramic compound to prepare a mixed solution of the polyethylene oxide copolymer and the ceramic compound, and then stirred for 24 hours using a magnetic bar. At this time, the mixed solution of the polyethylene oxide copolymer and the ceramic compound is composed of 20 parts by weight of trimethylolpropane trimethacrylate as a crosslinking agent, 1 part by weight of benzoyl peroxide as an initiator, 36 parts by weight of LiTFSI as a lithium salt, 40 parts by weight of LSTP as a ceramic compound, and 100 parts by weight of the polyethylene oxide copolymer as a reference, wherein acetonitrile is used as a solvent, and the concentration of the polymer contained in the mixed solution of the polymer and the ceramic compound, namely the polyethylene oxide copolymer, is set to 11.1% by weight, and the concentration of the polyethylene oxide and the ceramic compound is set to 14.9% by weight.

[0150] The prepared mixed solution was cast on the lower substrate of the button cell, and then dried at room temperature for 12 hours, and then dried at 100° C. for 3 hours to form an electrolyte membrane with a thickness of 200 μm. Thus, a composite solid electrolyte was prepared.

[0151] Comparative Example:

[0152] Comparative Example 1: Polymer solid electrolyte containing only modified PEO (without ceramic compound)

[0153] A polymer solid electrolyte was prepared in the same manner as in Example 1, except that the ceramic compound was not used.

[0154] Comparative Example 2: Composite solid electrolyte containing unmodified PEO and ceramic compound

[0155] A composite solid electrolyte was prepared in the same manner as in Example 1, except that a PEO homopolymer (Sigma Aldrich, molecular weight (Mw): 4,000,000 g / mol) not substituted with a crosslinkable functional group was used, and no crosslinking agent or initiator was added.

[0156] Comparative Example 3: Polymer solid electrolyte containing unmodified PEO (without ceramic compound)

[0157] The polymer solid electrolyte was prepared in the same manner as in Example 1, except that a ceramic compound was not used, a PEO homopolymer (Sigma Aldrich, molecular weight (Mw): 4000000 g / mol) not substituted with a crosslinkable functional group was used, and no crosslinking agent or initiator was added. At this time, when preparing a mixed solution, the molar ratio of the PEO copolymer to the lithium salt LiTFSI was set to 20:1, which was added to acetonitrile as a solvent to prepare a mixed solution. The concentration of the PEO copolymer in the mixed solution was set to 3% (wt%).

[0158] Experimental example

[0159] Experimental Example 1: Measurement of ionic conductivity of solid electrolyte

[0160] In order to measure the ionic conductivity of the solid electrolytes prepared in the examples and comparative examples, a 2 A solid electrolyte was formed on the lower substrate of a button cell, and then a button cell for measuring ionic conductivity was manufactured using SUS as a blocking electrode.

[0161] The resistance was measured using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument) at 25° C. under the conditions of an amplitude of 10 mV and a scanning range of 1 Hz to 0.1 MHz, and then the ionic conductivity of the solid electrolyte was calculated according to the following Equation 1.

[0162] [Formula 1]

[0163]

[0164] Where, in Equation 1, σ i is the ionic conductivity of the solid electrolyte (S / cm), R is the resistance of the solid electrolyte measured by electrochemical impedance spectroscopy (Ω), L is the thickness of the solid electrolyte (μm), and A is the area of ​​the solid electrolyte (cm 2 ).

[0165] Table 1 below shows the calculated values ​​of ionic conductivity.

[0166] [Table 1]

[0167] Ionic conductivity (S / cm, 25°C) Example 1 <![CDATA[1.4x 10 -4 ]]> Comparative Example 1 <![CDATA[2.3x 10 -5 ]]> Comparative Example 2 <![CDATA[2.9x 10 -7 ]]> Comparative Example 3 <![CDATA[4.9x 10 -8 ]]>

[0168] As shown in Table 1, Example 1, which is a composite solid electrolyte prepared using PEO containing a cross-linkable functional group and a ceramic compound, was found to have the highest ionic conductivity.

Claims

1. A composite solid electrolyte comprising: A polymer comprising a PEO (polyethylene oxide) type copolymer containing a cross-linkable functional group; and Ceramic compounds, in, At least a portion of the cross-linkable functional groups form cross-links with each other, so that the polymer forms a three-dimensional network structure, and Wherein, the ceramic compound is contained in the three-dimensional network structure.

2. The composite solid electrolyte according to claim 1, wherein The composite solid electrolyte further comprises a cross-linking agent.

3. The composite solid electrolyte according to claim 2, wherein: At least a portion of the cross-linkable functional groups form cross-linked bonds with each other through the cross-linking agent.

4. The composite solid electrolyte according to claim 1, wherein The crosslinkable functional group is bonded to the PEO-based copolymer through the alkylene linking group having 0 to 10 carbon atoms or the oxyalkylene linking group, wherein the alkylene linking group having 0 carbon atoms represents a single bond, and The cross-linkable functional group is selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group. 5 . The composite solid electrolyte according to claim 1 , further comprising a lithium salt dispersed on the polymer forming the three-dimensional network structure.

6. The composite solid electrolyte according to claim 1, wherein The PEO (polyethylene oxide)-based copolymer is a copolymer comprising repeating units of the following chemical formulas 1 to 3: [Chemical formula 1] [Chemical formula 2] [Chemical formula 3] Wherein, in Chemical Formulas 1 to 3, R1 represents -CH2-O-(CH2-CH2-O) k -R3, wherein k is 0 to 20, and R3 represents an alkyl group having 1 to 5 carbon atoms, R2 represents a substituent formed by bonding one or more crosslinkable functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, a nitro group, a cyano group, an amine group, an amide group, an epoxy group, and an allyl group to a polymer chain through an alkylene linking group having 0 to 10 carbon atoms or an oxyalkylene linking group, wherein the alkylene linking group having 0 carbon atoms represents a single bond, and l, m and n are the number of repetitions of the repeating unit, wherein l and n are each independently an integer from 1 to 1000, and m is an integer from 0 to 1000.

7. The composite solid electrolyte according to claim 1, wherein The ceramic compound includes an oxide-based solid electrolyte selected from lithium metal oxides or lithium metal phosphates.

8. The composite solid electrolyte according to claim 1, wherein The ceramic compound includes at least one oxide solid electrolyte selected from the group consisting of lithium lanthanum zirconium oxide (LLZO) compounds, lithium silicon titanium phosphate (LSTP) compounds, lithium lanthanum titanium oxide (LLTO) compounds, lithium aluminum titanium phosphate (LATP) compounds, lithium aluminum germanium phosphate (LAGP) compounds and lithium lanthanum zirconium titanium oxide (LLZTO) compounds.

9. A method for preparing the composite solid electrolyte according to claim 1, the method comprising the following steps: forming a mixture of a polyethylene oxide (PEO)-based copolymer containing a cross-linkable functional group and a ceramic compound; and The PEO-based copolymer contained in the mixture is subjected to a cross-linking reaction.

10. The method according to claim 11, wherein: The cross-linking reaction is performed in the presence of at least one additive selected from the group consisting of a cross-linking agent and an initiator. 11 . An all-solid-state battery comprising an electrolyte layer comprising the composite solid electrolyte according to claim 1 .

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