Method for manufacturing a composite solid electrolyte and the composite solid electrolyte manufactured thereby

Abstract

The present invention relates to a method for manufacturing a composite solid electrolyte and a composite solid electrolyte manufactured by the method. The method includes the steps of: (S1) preparing a mixed solution containing a PEO (polyethylene oxide) copolymer having a cross-linking functional group and a ceramic compound; (S2) unwinding a substrate using an unwinder and feeding the substrate to a transport path; (S3) coating the mixed solution on the substrate to form a coating film; (S4) transporting the substrate with the coated film to a drying section and drying it to form a polymer film; (S5) transporting the polymer film to a deposition section and depositing a polar solvent thereon to form a composite solid electrolyte layer; and (S6) winding and recovering the substrate with the composite solid electrolyte layer using a rewinder.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority rights under Korean Patent Application No. 10-2022-0132766 dated October 14, 2022, and Korean Patent Application No. 10-2023-0136063 dated October 12, 2023, and all content disclosed in the documents of said Korean Patent Applications is incorporated herein by reference.

[0002] This invention relates to a method for producing a composite solid electrolyte and a composite solid electrolyte produced thereby. [Background technology]

[0003] Lithium-ion batteries, which use liquid electrolytes, have a structure in which the negative and positive electrodes are separated by a separator membrane. If the separator membrane is damaged by deformation or external impact, a short circuit may occur, which can lead to dangers such as overheating or explosion. Therefore, the development of solid electrolytes that can ensure safety in the field of lithium-ion secondary batteries is a very important issue.

[0004] Lithium-ion batteries using solid electrolytes offer several advantages, including increased battery safety, prevention of electrolyte leakage, improved battery reliability, and ease of manufacturing thin batteries. Furthermore, the ability to use lithium metal as the negative electrode increases energy density, leading to expectations of applications in small secondary batteries and high-capacity secondary batteries for electric vehicles, making them a promising next-generation battery.

[0005] Among solid electrolytes, polymer solid electrolytes utilize polymer materials with ion-conducting properties, or inorganic materials such as oxides or sulfides with ion-conducting characteristics. Composite polymer solid electrolytes, which are mixtures of polymer and inorganic materials, have also been proposed.

[0006] Conventional composite polymer solid electrolytes are manufactured by dispersing ceramic powders such as oxides in a polymer matrix. They have advantages such as higher stability compared to conventional liquid electrolytes and higher ionic conductivity compared to polymer solid electrolytes. However, they have the difficulty of meeting fundamental prerequisites, such as improving the dispersibility of ceramic particles such as oxides in the polymer matrix and optimizing the physical properties of the polymer matrix used. In particular, there was a limitation in that it was difficult to manufacture composite solid electrolytes with improved ionic conductivity using highly crystalline polymers such as polyethylene oxide (PEO). In other words, the high crystallinity of the polymer inhibits the mobility of the polymer chains, which restricts the movement of lithium ions within the polymer solid electrolyte, making it difficult to improve the ionic conductivity of the polymer solid electrolyte.

[0007] To overcome these limitations of conventional composite solid electrolytes, techniques have been developed to improve the ionic conductivity of composite solid electrolytes by modifying the structure of crystalline polymers or by adding a separate plasticizer to the polymer to improve the mobility of the polymer chains. However, solid polymer electrolytes manufactured using the aforementioned polymer structure modification or plasticizer addition methods may have difficulty achieving an ionic conductivity of 1 mS / cm or higher.

[0008] Therefore, in addition to polymer solid electrolytes produced by structural deformation of polymers, addition of separate plasticizers, or immersion of solid electrolytes in liquid electrolytes, there is a need for technological development of a method for producing composite solid electrolytes that can improve the ionic conductivity of the electrolyte and can be manufactured in a continuous process, as a pure solid electrolyte for all-solid-state batteries. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 1994-124713 [Overview of the project] Problem to be Solved by the Invention

[0010] The present invention provides a method for producing a composite solid electrolyte that improves ionic conductivity and enables continuous production processes, and a composite solid electrolyte produced by the method. Means for Solving the Problem

[0011] Therefore, one embodiment of the invention provides a method for producing a composite solid electrolyte, comprising the steps of: (S1) preparing a mixed solution containing a PEO (polyethylene oxide)-based copolymer having a crosslinkable functional group and a ceramic compound; (S2) unwinding a substrate using an unwinder and supplying the substrate to a transfer path; (S3) applying the mixed solution onto the substrate to form a coating film; (S4) transferring the substrate having the coating film formed thereon to a drying section and drying the substrate to form a polymer film; (S5) transferring the polymer film to a vapor deposition section and depositing a polar solvent to form a composite solid electrolyte layer; and (S6) winding and recovering the substrate including the composite solid electrolyte layer using a rewinder.

[0012] In the above production method, the mixed solution in step (S1) may further include one or more selected from the group consisting of a lithium salt, a crosslinking agent and an initiator. Further, such a mixed solution may contain 10 to 100 parts by weight, alternatively 10 to 60 parts by weight, of the ceramic compound relative to 100 parts by weight of the PEO (polyethylene oxide)-based copolymer.

[0013] Further, in the deposition of step (S5), the polar solvent may be naturally evaporated at room temperature or evaporated by heating, so that gas molecules of the polar solvent are included on the surface or inside the polymer chains.

[0014] On the other hand, in the above production method, the crosslinkable functional group is bonded to the PEO-based copolymer via an alkylene linker having 0 to 10 carbon atoms or an alkylene oxide linker, provided that an alkylene linker having 0 carbon atoms represents a single bond, and may be 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.

[0015] In a more specific example, the PEO (polyethylene oxide)-based copolymer may be a copolymer comprising repeating units represented by the following Chemical Formulas 1 to 3: [Chemical Formula 1]

Chemical Structure

Chemical Structure

Chemical Structure

[0016] Furthermore, in the above manufacturing method, the gas molecules of the polar solvent are polar compounds, and a composite solid electrolyte can be produced in which the content of the polar compounds is 0.1% by weight or more and less than 10% by weight on a total weight basis of the composite solid electrolyte.

[0017] In this case, the polar solvent may include one or more compounds selected from the group consisting of carbonate compounds and sulfonyl compounds. More specifically, the polar solvent may include one or more compounds selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), and sulfolane.

[0018] On the other hand, the ceramic compound may include one or more compounds 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) compounds.

[0019] Furthermore, in the above manufacturing method, steps (S1) to (S6) may be carried out continuously.

[0020] On the other hand, another embodiment of the invention provides a composite solid electrolyte manufactured by the method of one embodiment described above. Such a composite solid electrolyte comprises a polymer including a PEO copolymer containing crosslinkable functional groups; a ceramic compound; and a polar compound, wherein at least some of the crosslinkable functional groups form crosslink bonds with each other so that the polymer forms a three-dimensional network structure, and the polar compound may be contained within the three-dimensional network structure in a gaseous state or bonded to the polymer chain. [Effects of the Invention]

[0021] The method for producing a composite solid electrolyte according to the present invention allows for the production of the composite solid electrolyte in a continuous process, enabling mass production.

[0022] Furthermore, composite solid electrolytes can improve ionic conductivity by maintaining the inherent structural properties of the polymer without deformation or destruction of the polymer chains, while simultaneously improving the mobility of the polymer chains and uniformly distributing the ceramic particles within the composite solid electrolyte.

[0023] Furthermore, the composite solid electrolyte can exhibit improved ionic conductivity and mechanical properties by containing a minute amount of polar solvent (polar compound) in a gaseous state. [Brief explanation of the drawing]

[0024] [Figure 1] This is a flowchart of the method for producing the composite solid electrolyte of the present invention. [Modes for carrying out the invention]

[0025] The following describes specific embodiments in more detail to help understand the invention.

[0026] Terms and words used herein and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner and concept consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best describe their invention.

[0027] In this invention, the term "polymer film" refers to a film produced by coating and drying a mixed solution containing a PEO (polyethylene oxide) copolymer containing crosslinking functional groups and a ceramic mixture. Polymer chains containing crosslinking bonds formed by the crosslinking functional groups are formed inside the polymer film, and ceramic compounds are dispersed in the internal space of the polymer chains.

[0028] The term "composite solid electrolyte" as used in this invention refers to an electrolyte having a structure in which a polar compound, which is a gaseous molecule of the polar solvent, is contained on the surface or inside the polymer chain, obtained by depositing the polymer film with a polar solvent.

[0029] As used herein, the term "bonding" refers to a form in which a polar compound (a vapor-deposited polar solvent) is "bonded" to a polymer chain, such as a PEO copolymer chain. The term "bonding" broadly refers to a form in which the polar solvent, through vapor deposition, maintains a state in which the gaseous polar compound, which is the polar solvent molecule, is fixed to the polymer chain. In other words, the term "bonding" is not limited to a specific type of physical bond, chemical bond, etc., but includes a state fixed by various bonds, including these physical and chemical bonds, or a state fixed by simple attachment such as adsorption, or a state in which it is contained within a three-dimensional network structure formed by the cross-linking of the polymer and is fixed adjacent to the polymer chain or cross-linking structure.

[0030] As used herein, the term "three-dimensional network structure" refers to a structure comprising a three-dimensional solid-shaped frame and an internal space formed by the frame, wherein the frame may include polymer chains comprising crosslinks formed by the crosslinkable functional groups, such as crosslinks between crosslinkable functional groups and / or crosslinks between crosslinkable functional groups and crosslinking agents. The three-dimensional network structure can also be called a crosslinked structure.

[0031] In this specification, the presence or inclusion of a polar compound (polar solvent) in a "gaseous state" in a composite solid electrolyte is distinguished from cases where the polar solvent or the electrolyte containing it is injected in a liquid state. It means that the polar compound is deposited in a vapor state and exists in a state distinct from the liquid-injected electrolyte immediately after the manufacture of the composite solid electrolyte or during the charge-discharge process of an all-solid-state secondary battery containing it. However, depending on the storage or operating conditions of the composite solid electrolyte and / or secondary battery, the deposited polar compound may be in a locally or temporarily liquefied state. Even in this case, the deposited polar compound exhibits higher mobility than the polar solvent injected in a liquid state and shows a different state from the liquid polar solvent, so it is also considered to be present or contained in a "gaseous state".

[0032] On the other hand, conventionally, to improve the ionic conductivity of solid electrolytes, composite solid electrolytes were manufactured by dispersing ceramic compounds such as oxides in a polymer matrix. However, such composite solid electrolytes have problems such as the non-uniform distribution of oxide-based ceramic particles in the polymer matrix, or a decrease in ionic conductivity when a highly crystalline polymer such as polyethylene oxide is used as the polymer.

[0033] Conventionally, to improve the ionic conductivity of a solid electrolyte, the solid electrolyte was either immersed in or supported in a liquid electrolyte or solvent, or the liquid electrolyte or solvent was directly injected into the solid electrolyte in a liquid state. While directly adding a liquid electrolyte or solvent to a solid electrolyte does improve its ionic conductivity, this improvement is merely due to the high ionic conductivity of the liquid itself, and the degree of improvement is insufficient, requiring the injection of a considerable amount of liquid electrolyte. In other words, lithium ion conduction is carried out by the liquid electrolyte added to the solid electrolyte rather than by the inherent properties of the solid electrolyte, and therefore does not improve the properties of the solid electrolyte itself. Furthermore, when a liquid electrolyte or solvent is directly added to a solid electrolyte in a liquid state, there is a problem in that the structure of the solid electrolyte can collapse due to unexpected side reactions between the polymer and the liquid phase, such as damage to the polymer chain or breakage of bonds within the polymer, resulting in a decrease in ionic conductivity.

[0034] Furthermore, when a solvent or liquid electrolyte is directly injected into a solid electrolyte, the rapid diffusion of liquid phase molecules into the solid electrolyte can cause rapid relaxation of polymer chains, promoting gelation at the surface. This can lead to a decrease in mechanical properties, and problems such as leakage of the liquid electrolyte may not be completely resolved.

[0035] Furthermore, in the case of the conventional technology described in Japanese Patent Publication No. 1994-124713, there was a technique of depositing a solvent onto a general PEO (polyethylene oxide) polymer, but in this case, there was a problem that the internal structure of the polymer would collapse and ionic conductivity could not be ensured.

[0036] Therefore, the inventors crosslinked a PEO (polyethylene oxide) copolymer modified with crosslinkable functional groups and mixed a ceramic compound together during the crosslinking process to produce a polymer film in which the ceramic compound is uniformly dispersed in the internal space of the polymer chain. Furthermore, by bringing the polymer film into contact with the vapor of a polar solvent, a minute amount of gaseous molecules of the polar solvent were made to bond to the polymer chain or be included in the internal space of the polymer chain.

[0037] The composite solid electrolyte thus produced comprises a polymer including a PEO copolymer containing crosslinkable functional groups; a ceramic compound; and a polar compound, wherein at least a portion of the crosslinkable functional groups form crosslink bonds with each other, so that the polymer forms a three-dimensional network structure, and the polar compound may be contained within the three-dimensional network structure in a gaseous state or may exhibit a structure bonded to the polymer chain.

[0038] Such composite solid electrolytes were found to exhibit improved ionic conductivity despite containing trace amounts of polar compounds derived from polar solvents in a gaseous state. This is presumed to be because the gaseous polar compounds affect the physical properties of the PEO copolymer, such as its crystallinity, increasing the chain mobility of the polymer chains, thereby improving the conductivity of lithium ions contained in the polymer solid electrolyte. Furthermore, such ionic conductivity can be further improved by uniformly dispersing the ceramic compound.

[0039] Furthermore, the inventors have developed a method for manufacturing composite solid electrolytes that exhibit improved ionic conductivity based on the principle described above, enabling mass production through a continuous process.

[0040] The following describes in detail the manufacturing method for such composite solid electrolytes.

[0041] Method for manufacturing a composite solid electrolyte One embodiment of the invention provides a method for producing a composite solid electrolyte, and an example of the flowchart is shown in Figure 1.

[0042] Referring to Figure 1, the method for producing a composite solid electrolyte according to one embodiment includes: (S1) the step of producing a mixed solution containing a PEO (polyethylene oxide) copolymer containing a crosslinkable functional group and a ceramic compound; (S2) the step of unwinding the substrate using an unwinder and supplying it to a transfer path; (S3) the step of applying the mixed solution onto the substrate to form a coating film; (S4) the step of transferring the substrate on which the coating film has been formed to a drying section and drying it to form a polymer film; (S5) the step of transferring the polymer film to a deposition section and depositing a polar solvent to form a composite solid electrolyte layer; and (S6) the step of winding and recovering the substrate containing the composite solid electrolyte layer using a rewinder. At this time, steps (S1) to (S6) may be performed continuously.

[0043] The manufacturing method of one embodiment will be described in more detail below, step by step.

[0044] In step (S1), a mixed solution containing a PEO (polyethylene oxide) copolymer containing a crosslinking functional group and a ceramic compound can be produced.

[0045] The aforementioned mixed solution can be produced by mixing the PEO-based copolymer and the ceramic compound in a solvent, and additionally, by mixing one or more of the lithium salt, crosslinking agent, and initiator together. By mixing the lithium salt, an electrolyte can be formed, and by mixing the crosslinking agent and / or initiator, crosslinked bonds of the PEO-based copolymer can be formed.

[0046] The solvent is not particularly limited as long as it can dissolve the PEO copolymer in a mixture of one or more of the lithium salt, crosslinking agent, and initiator, and can be easily removed by a drying process. For example, the solvent may be acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, dimethyl sulfoxide (DMSO), methylpyrrolidone (NMP), or dimethylformamide (DMF). Such a solvent is a reaction medium for crosslinking and is distinct from polar solvents contained in liquid electrolytes, and is completely removed by drying after crosslinking.

[0047] The concentration of the mixed solution can be appropriately adjusted, taking into consideration the degree to which the molding process for manufacturing the composite solid electrolyte can proceed smoothly. Specifically, the concentration of the mixed solution may refer to the concentration of the polymer in the mixed solution (w / w%). In this case, the concentration of the polymer may refer to the concentration of the PEO copolymer. For example, the concentration of the mixed solution may be 5% to 20% by weight, and specifically, it may be 5% or more by weight, 7% or more by weight, or 9% or more by weight, or 13% or less by weight, 17% or less by weight, or 20% or less by weight. If the concentration of the mixed solution is less than 5% by weight, the concentration may be excessively diluted, reducing the mechanical strength of the composite solid electrolyte or causing it to run off the substrate when applied. If it exceeds 20% by weight, it may be difficult to dissolve the lithium salt in the mixed solution at the desired concentration, the viscosity may be high, reducing solubility, or it may be difficult to apply it in a uniform thin film form.

[0048] Furthermore, there may be two or more types of crosslinking functional groups. The crosslinking functional groups may be the same or different from each other, and preferably different. If the crosslinking functional groups are different, the PEO copolymer may contain multiple types of repeating units, each containing one of these functional groups. Moreover, if multiple types of crosslinking functional groups are included, it may become easier to control the mobility and ionic conductivity of the polymer chain.

[0049] The aforementioned crosslinkable functional group refers to a functional group that can form crosslinks between itself and / or with other functional groups via a crosslinking agent, and can be attached to the main chain of a polymer chain in the form of a side chain.

[0050] Specifically, the crosslinkable functional group may be directly bonded to the main chain of the PEO copolymer, but it can also be bonded via an alkylene or alkylene oxide linker. For this reason, the crosslinkable functional group can be bonded via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (however, an alkylene linker having 0 carbon atoms shows a single bond), and may be one or more selected from the group consisting of hydroxyl group, carboxyl group, isocyanate group, nitro group, cyano group, amine group, amide group, epoxy group, and allyl group.

[0051] In a more specific embodiment, the PEO copolymer containing the crosslinkable functional group may be a copolymer containing repeating units of the following chemical formulas 1 to 3: [Chemical formula 1] [ka] [Chemical formula 2] [ka] [Chemical formula 3] [ka] In the above chemical formulas 1 to 3, R1 is -CH2-O-(CH2-CH2-O) k -R3 is represented, where k is 0 to 20, and R3 represents an alkyl group with 1 to 5 carbon atoms. R2 represents a substituent in which one or more crosslinking functional groups selected from the group consisting of hydroxyl groups, carboxyl groups, isocyanate groups, nitro groups, cyano groups, amine groups, amide groups, epoxy groups, and allyl groups are bonded to the polymer chain via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (where the alkylene linker having 0 carbon atoms shows a single bond). l, m, and n are the number of repetitions in the repeating unit, where l and n are independent integers between 1 and 1000, and m is an integer between 0 and 1000.

[0052] For example, the crosslinking functional group of R2 can form a polymer having a matrix form of a three-dimensional network structure formed by the crosslinking. The formation of the three-dimensional network structure by the crosslinking can improve the mechanical properties of the composite solid electrolyte, and a composite solid electrolyte can be provided in which the gaseous polar compound is contained or bonded within such a three-dimensional network structure, thereby improving ionic conductivity.

[0053] Furthermore, it is obvious that the PEO copolymer may also contain two or more repeating units of chemical formula 3 in which R2 is a different crosslinking functional group, and may also contain one or more repeating units of chemical formula 2.

[0054] If l, m, and n are each less than 1, forming a polymer is difficult due to the small molecular weight. If l, m, and n are each greater than 1000, the viscosity increases, reducing solubility during the production of the polymer solution and potentially making film formation for solid electrolyte production difficult. In particular, if the number of repeating units of chemical formula 3 containing crosslinking functional groups exceeds 1000 among l, m, and n, the degree of crosslinking may increase excessively, reducing the mobility of the polymer chain and decreasing the ionic conductivity of the composite solid electrolyte.

[0055] In this specification, "hydroxyl group" refers to the -OH group.

[0056] In this specification, "carboxyl group" refers to a -COOH group.

[0057] In this specification, "isocyanate group" refers to a -N=C=O group.

[0058] In this specification, "nitro group" refers to the -NO2 group.

[0059] In this specification, "cyano group" refers to a -CN group.

[0060] In this specification, "amide group" refers to -C(=O)NR'R'', where R' and R'' are independently hydrogen or C1-C5 alkyl groups, or R' and R'' can form a heterocycle having C4-C8 atoms in the ring structure together with the N atom to which they are attached.

[0061] In this specification, "amine group" may be selected from the group consisting of monoalkylamine group; monoarylamine group; monoheteroarylamine group; dialkylamine group; diarylamine group; diheteroarylamine group; alkylarylamine group; alkylheteroarylamine group; and arylheteroarylamine group, and the number of carbon atoms is not particularly limited, but is preferably 1 to 30. Specific examples of the amine group include, but are not limited to, methylamine group, dimethylamine group, ethylamine group, diethylamine group, phenylamine group, naphthylamine group, biphenylamine group, dibiphenylamine group, anthracenylamine group, 9-methyl-anthracenylamine group, diphenylamine group, phenylnaphthylamine group, ditolylamine group, phenyltolylamine group, triphenylamine group, biphenylnaphthylamine group, phenylbiphenylamine group, biphenylfluorenylamine group, phenyltriphenylenylamine group, and biphenyltriphenylenylamine group. Furthermore, "amino group" refers to -NH2.

[0062] In this specification, "allyl group" refers to the -CH2-CH=CH2 group.

[0063] The weight-average molecular weight (Mw) of the copolymer containing chemical formulas 1 to 3 may be between 100,000 g / mol and 2,000,000 g / mol, and more specifically, it may be 100,000 g / mol or more, 200,000 g / mol or more, or 300,000 g / mol or more, and may be 1,600,000 g / mol or less, 1,800,000 g / mol or less, or 2,000,000 g / mol or less. If the weight-average molecular weight (Mw) of the copolymer is less than 100,000 g / mol, it may not satisfy the mechanical properties of a film capable of forming a composite solid electrolyte. If the weight-average molecular weight (Mw) of the copolymer exceeds 2,000,000 g / mol, the solubility decreases during the production of the polymer solution due to increased viscosity, which may make it difficult to mold the polymer film for the production of a composite solid electrolyte. Furthermore, during the manufacturing of the polymer film, the ionic conductivity of the composite solid electrolyte may decrease due to a decrease in chain mobility caused by an increase in crystallinity within the film. In particular, if the number of repeating units containing crosslinking functional groups among l, m, and n exceeds 1000, the degree of crosslinking may increase excessively, reducing the mobility of the polymer chains and thus decreasing the ionic conductivity of the composite solid electrolyte.

[0064] Furthermore, the copolymer may be a random copolymer or a block copolymer.

[0065] On the other hand, the composite solid electrolyte may include a ceramic compound. The ceramic compound has lithium ion transfer capability to improve lithium ion conductivity, and preferably contains lithium atoms and does not store lithium, but has the function of moving lithium ions, thereby improving the ionic conductivity of the composite solid electrolyte.

[0066] Further, the ceramic compound may be contained in a state of being uniformly dispersed in the internal space of the crosslinked polymer chains in the polymer film formed by crosslinking bonds induced during the drying in step (S4). The ceramic compound is co-mixed when the mixed solution is formed, and can be uniformly dispersed without agglomeration in the internal space between the crosslinked polymer chains. Such a ceramic compound, with its uniform dispersion state, can be advantageous for improving the mechanical strength and ionic conductivity of the composite solid electrolyte.

[0067] Further, the ceramic compound may be in the form of particles. Due to the morphological feature of being particles, the ceramic compound may be contained in a more uniformly dispersed state inside the composite polymer solid electrolyte. The particles of the ceramic compound may be spherical, and the diameter thereof may be 100 nm to 1000 nm. If the diameter is less than 100 nm, the amorphization effect due to the decrease in crystallinity of the polymer is insignificant; if the diameter exceeds 1000 nm, the dispersibility may decrease due to increased aggregation between particles, making it difficult to achieve uniform dispersion.

[0068] The ceramic compound may be an oxide-based or phosphate-based compound, and for example, may be an oxide-based solid electrolyte in the form of a lithium metal oxide or a lithium metal phosphate. More specifically, the ceramic compound is garnet-type lithium-lanthanum-zirconium oxide (LLZO, Li7La3Zr2O 12 ) compound, perovskite-type lithium-lanthanum-titanium oxide (LLTO, Li3xLa 2 / 3-x TiO3) compound, phosphate-based NASICON-type lithium-aluminum-titanium phosphate (LATP, Li 1+x Al x Ti 2-x (PO4)3) compound, lithium-aluminum-germanium phosphate (LAGP, Li 1.5 Al 0.5 Ge 1.5One or more compounds may be selected from the group consisting of (PO4)3) compounds, lithium-silicon-titanium phosphate (LSTP, LiSiO2TiO2(PO4)3) compounds, and lithium-lanthanum-zirconium-titanium oxide (LLZTO) compounds. More preferably, one or more oxide-based solid electrolytes 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.

[0069] The oxide-based solid electrolyte, consisting of the aforementioned oxide-based or phosphate-based compound, generally has a maximum temperature of 10 at room temperature. -4 ~10 -3 It has an ionic conductivity value of S / cm, is stable in the high-voltage range, and has the advantages of being stable in air, easy to synthesize, and easy to handle.

[0070] Therefore, by further including the ceramic compound in the composite solid electrolyte described above, the disadvantages of polymer-based solid electrolytes can be compensated for.

[0071] Furthermore, the ceramic compound does not easily burn or ignite even under high-temperature conditions of 400°C or higher, thus exhibiting high high-temperature stability. Therefore, when the composite solid electrolyte contains the ceramic compound, it is possible to improve not only the mechanical strength of the composite solid electrolyte but also its high-temperature stability and ionic conductivity.

[0072] The ceramic compound may be present in an amount of 10 to 100 parts by weight, or 10 to 60 parts by weight, per 100 parts by weight of the PEO copolymer containing the crosslinking functional group.

[0073] If the ceramic compound is present in an excessively small amount, the reduction in polymer crystallinity and amorphous effect due to the ceramic compound will decrease, resulting in a less significant increase in the ionic conductivity of the composite solid electrolyte, and the mechanical properties may not reach the expected level due to the formation of the composite.

[0074] If the ceramic compound is present in an excessively large amount, the ceramic compound will not be uniformly dispersed within the polymer, and the ceramic compound particles will aggregate and clump together, resulting in the production of a composite solid electrolyte with reduced ionic conductivity.

[0075] In one embodiment of the invention, the lithium salt can be used as a raw material for forming an electrolyte. The lithium salt is contained in a dissociated ionic state in the internal space between the polymer chains, thereby improving the ionic conductivity of the composite solid electrolyte. At least some of the cations and / or anions dissociated from the lithium salt remain bound to the polymer chains and can exhibit mobility during charging and discharging of the battery.

[0076] The aforementioned lithium salts are (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 It may contain one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, LiC(CF3SO2)3, lithium chloroborane, lithium lower aliphatic carboxylate, and lithium tetraphenylborate.

[0077] Furthermore, the lithium salt may be present in 25 to 45 parts by weight per 100 parts by weight of the PEO copolymer containing the crosslinking functional group, specifically, 25 parts by weight or more, 30 parts by weight or more, or 35 parts by weight or more, or 40 parts by weight or less, or 45 parts by weight or less. If the lithium salt content is less than 25 parts by weight, the ionic conductivity of the composite solid electrolyte may decrease, and if it exceeds 45 parts by weight, the mechanical strength may decrease.

[0078] The crosslinking agent can form crosslink bonds with the crosslinkable functional group, and these crosslink bonds may be formed by hydrogen bonds, Lewis acid-base interactions, ionic bonds, coordination bonds, or radical polymerization.

[0079] The crosslinking agent is not particularly limited as long as it is a crosslinking agent capable of forming crosslink bonds with the crosslinkable functional group. For example, the crosslinking agent is trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethylene glycol dimethyl acrylate (hereinafter referred to as "EGDMA"), 1,3-diisopropenylbenzene (DIP), 1,4-diacryloyl piperazine, 2-(diethylamino)ethyl methacrylate, 2,6-bisacryloylamidopyridine, 3-(acryloxy)-2-hydroxypropyl methacrylate, 3,5-bis(acrylamide)benzoic acid (3,5-bis(acrylamido)benzoic acid), 3-aminopropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-methylacryloxypropyltrimethoxysilane, bis-(1-(tert-butylperoxy)-1-methylethyl)-benzene, dicumyl peroxide, dimethacrylate, divinylbenzene, ethylene glycol maleic rosinate acrylate N,O-bisacryloylphenylalaninol, N,O-bismethacryloylethanolamineOne or more polyfunctional crosslinking agents selected from the group consisting of O-bismethacryloyl ethanolamine, pentaerythritol triacrylate, phenyltrimethoxysilane, tetramethoxysilane, tetramethylene, tetraethoxysilane, and triallyl isocyanurate, for example, a polyvalent compound with two or more functions.

[0080] Furthermore, the crosslinking agent may be present in an amount of 1 to 30 parts by weight per 100 parts by weight of the PEO copolymer containing the crosslinking functional group. If the amount of the crosslinking agent is less than 1 part by weight, sufficient crosslinking with the crosslinking functional group may not occur, and if it exceeds 30 parts by weight, excessive crosslinking may occur, which may actually decrease the mobility of the polymer chain and thus lower the ionic conductivity.

[0081] In one embodiment of the invention, the initiator induces a radical polymerization reaction between the crosslinkable functional groups to form crosslinks between the crosslinkable functional groups. The functional group that enables the radical polymerization reaction may be a functional group containing vinyl at its terminal end, or it may be, for example, an allyl group.

[0082] The initiator is not particularly limited as long as it is an initiator capable of inducing a radical polymerization reaction between the crosslinking functional groups. For example, the initiator may include one or more selected from the group consisting of benzoyl peroxide, azobisisobutyronitrile, lauroyl peroxide, cumene hydroperoxide, diisopropylphenyl-hydroperoxide, tert-butyl hydroperoxide, p-menthane hydroperoxide, and 2,2'-azobis(2-methylpropionitrile).

[0083] The initiator can be used in an amount of 0.5 to 2 parts by weight per 100 parts by weight of the PEO copolymer containing the crosslinking functional group. When used within this range, it is possible to induce radical polymerization reactions between the crosslinking functional groups and efficiently form crosslinks.

[0084] On the other hand, in step (S2), the substrate can be unwound using the unwinder and supplied to the transfer path.

[0085] The aforementioned rewinding machine rewinds a base material wound in a roll shape and supplies it along a predetermined transfer path, and can rewind and supply the base material by its own drive. In addition, in step (S6), the base material can be rewinded and supplied by the driving force of a rewinder that winds the base material on which the composite solid electrolyte layer is formed.

[0086] Therefore, the production of a composite solid electrolyte according to one embodiment may be a roll-to-roll process.

[0087] Furthermore, the substrate is not particularly limited as long as it serves as a support for the coating film, and may be in the form of a film. For example, the substrate may be SUS (Stainless Use Steel), polyethylene terephthalate film, polytetrafluoroethylene film, polyethylene film, polypropylene film, polybutene 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.

[0088] On the other hand, in step (S3), the mixed solution can be continuously applied to the substrate to form a coating film.

[0089] The coating method is not particularly limited as long as it is a method that can form a coating film of the mixed solution on the substrate. For example, the coating method may be bar coating, roll coating, spin coating, slit coating, die coating, blade coating, comma coating, slot die coating, lip coating, spray coating, or solution casting.

[0090] As one specific example of the coating method, a solution casting method can be used. More specifically, after putting the mixed solution produced in step (S1) into a mixer, the mixer can be positioned on the substrate and the mixed solution can be continuously cast onto the substrate supplied in a unidirectional transfer path to form a coating film.

[0091] Furthermore, in step (S4), the coating film formed on the substrate can be transferred to a drying section and dried to form a polymer film.

[0092] The drying method described above can be a hot air drying method, which dries the film using hot air at a certain temperature range. However, it is not limited to these examples, and any method that can dry the coating film on the substrate film on which the coating film is formed is acceptable.

[0093] Specifically, the drying may be carried out at 50°C to 250°C, or more specifically, the drying temperature may be 50°C or higher, 70°C or higher, or 90°C or higher, and may be 120°C or lower, 150°C or lower, 200°C or lower, or 250°C or lower. If the drying temperature is below 50°C, the coating film formed by applying the mixed solution onto the substrate may not dry sufficiently and may flow off as a liquid phase, and if it exceeds 250°C, damage may occur to the coating film applied to the substrate or foaming may occur, resulting in an inability to form a smooth coating film.

[0094] Alternatively, the drying may include primary drying and secondary drying. The primary drying removes a portion of the solvent contained in the coating film, allowing the film to take shape, and the secondary drying allows the formation of crosslinking bonds between crosslinkable functional groups induced by the initiator and / or crosslinking bonds between the crosslinkable functional groups and the crosslinking agent.

[0095] The primary drying can be carried out at room temperature for 5 to 20 hours, and the secondary drying may be carried out at 50°C to 250°C as described above. When the drying process is carried out by primary and secondary drying in this way, a film with a uniform shape is formed, and internal cross-linking bonds can be formed more effectively.

[0096] Furthermore, the drying section is not limited to a single stage; if the drying path is long, multiple drying sections can be formed to improve drying efficiency. For example, three or more drying sections may be formed.

[0097] As a result of the drying process, a crosslinking reaction occurs in the polymer film, and it may contain polymer chains that include crosslinks. These crosslinks may include crosslinks between crosslinkable functional groups and / or crosslinks between crosslinkable functional groups and a crosslinking agent. For example, at least some of the crosslinkable functional groups can form crosslinks with each other via the crosslinking agent to form the three-dimensional network structure described above.

[0098] The crosslinking between the aforementioned crosslinkable functional groups may be urethane bonds, ester bonds, hydrogen bonds, or bonds formed by radical polymerization reactions involving vinyl groups at the allyl group (-CH2-CH=CH2) termini, but are not limited to these examples.

[0099] Furthermore, the crosslinking bond between the crosslinkable functional group and the crosslinking agent may be formed by hydrogen bonding, Lewis acid-base interaction, ionic bonding, coordination bonding, or radical polymerization.

[0100] In the internal space of the polymer chain in which such crosslinking bonds are formed, for example, within a three-dimensional network structure, the ceramic compound may be uniformly dispersed, or the lithium salt may be included in a dissociated ionic state.

[0101] On the other hand, in step (S5), the polymer film can be transferred to the deposition section and a polar solvent can be deposited to produce a composite solid electrolyte.

[0102] The deposition may involve either allowing the polar solvent to evaporate naturally at room temperature or by heating to bond gaseous molecules of the polar solvent to the polymer chains inside the polymer film, or to include gaseous molecules of the polar solvent in the internal space of the polymer chains.

[0103] Thus, by leaving the polar solvent at room temperature or by deposition through heating, the polar solvent may be uniformly diffused onto the surface and / or interior of the polymer, and the gaseous molecules of the polar solvent may be bonded to the polymer chain or uniformly dispersed within the internal space of the polymer chain.

[0104] When the polar solvent is left at room temperature during the deposition process, a small amount of polar solvent with a low boiling point can be gradually permeated into the solid electrolyte at room temperature, effectively inducing a change in the conformation of the cross-linked polymer chains within the solid film.

[0105] Furthermore, heating the polar solvent during the deposition process can improve the deposition rate. The heating temperature is not particularly limited as long as it allows the polar solvent to undergo a phase change into vapor; for example, it could be between 30°C and 80°C. While typical PEO copolymers melt at 60°C, PEO copolymers modified with the crosslinking functional group can withstand temperatures up to 80°C when forming a crosslinked structure, thus further increasing the deposition rate. Moreover, the heating method is not limited to any method that can supply the energy needed to generate vapor. For example, direct heating methods using a burner or furnace, or indirect heating methods using a heater or steam tube can be used, but the method is not limited to these examples.

[0106] When heating, if the temperature is excessively high, it may exceed the boiling point of the polar solvent or induce deformation of the polymer. This has the disadvantage of making it difficult to control the evaporation rate of the polar solvent during deposition. Therefore, in order to deposit a small amount of polar solvent, it is preferable to carry out the deposition at a heating temperature within the appropriate range as defined above.

[0107] As described above, composite solid electrolytes can be manufactured that contain polar compounds, which are gaseous molecules of polar solvents contained within the internal space of polymer chains, or that are bonded to cross-linked polymer chains by vapor deposition.

[0108] The polar compound is a gaseous molecule of a polar solvent used in the vapor deposition process. During vapor deposition, the gaseous molecule of the polar solvent may be adsorbed onto the polymer and then diffuse into the polymer chain, becoming contained on or inside the polymer chain. Specifically, the polar compound may be contained in a form bound to the polymer chain or dispersed in the internal space between the polymer chains.

[0109] The ionic conductivity of the final manufactured composite solid electrolyte can be improved by including the polar compound in a form that is bound to polymer chains or dispersed in the internal spaces between polymer chains.

[0110] Such composite solid electrolytes contain substantially no liquid solvent or electrolyte, but include trace amounts of polar compounds contained or bonded in a gaseous state by the deposition process. Such composite solid electrolytes can be identified, for example, by observing the electrolyte layer containing them with the naked eye or an electron microscope after separation from an all-solid-state battery; no liquid components are observed on the surface of the electrolyte layer. In contrast, when a liquid polar solvent or electrolyte is injected into a composite solid electrolyte, liquid components or wettable components can be observed on the surface of the electrolyte layer. Furthermore, composite solid electrolytes containing the polar compound in a gaseous state through deposition exhibit significantly higher ionic conductivity compared to those containing a liquid polar solvent or electrolyte. Such comparisons of ionic conductivity can also confirm the presence of the polar compound in a gaseous state through deposition.

[0111] Specifically, polar compounds that are bound to the polymer chains or contained in the internal spaces between the polymer chains act as plasticizers within the polymer, causing it to plasticize. The plasticized polymer has an increased amorphous region, which improves the mobility of the polymer chains. This improved mobility increases the ion hopping effect within the polymer, thereby improving the ionic conductivity of the composite solid electrolyte.

[0112] Furthermore, the polar compound can act as an intermediate for smooth ion transfer through ion hopping. Since the affinity between lithium ions and the polar compound is stronger than the affinity between lithium ions and the ether oxygen of the PEO copolymer, lithium ions can be transferred more quickly and easily within the polymer on which the polar compound is adsorbed. In other words, the influx of the polar compound, which is a polar solvent molecule, into the polymer increases the cation solvation effect of lithium ions, thereby improving ion mobility and thus improving the ionic conductivity of the composite solid electrolyte.

[0113] Furthermore, the polar solvent or the corresponding polar compound may include one or more compounds selected from the group consisting of carbonate compounds and sulfonyl compounds.

[0114] Specifically, the polar compound may include one or more selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), and sulfolane, or a combination thereof.

[0115] The content of the polar compound may be between 0.1% by weight and less than 10% by weight on a total weight basis of the composite solid electrolyte. For example, the content of the polar compound may be 0.1% by weight or more, 1% by weight or more, 2% by weight or more, or 8% by weight or less, 9% by weight or less, or less than 10% by weight. If the content of the polar compound is less than 0.1% by weight, it is difficult to induce a change in the chain conformation of the polymer, and the ionic conductivity of the composite solid electrolyte does not improve. If the content of the polar compound is 10% by weight or more, the solid electrolyte has a high liquid content, exhibiting the properties of a semi-solid battery, and there is a problem of reduced mechanical strength of the composite solid electrolyte due to polymer gelation.

[0116] Additionally, in step (S6), the substrate containing the composite solid electrolyte layer can be wound up and recovered using a rewinder.

[0117] The rewinder can recover the substrate containing the composite solid electrolyte layer by winding it into a roll shape, and can wind the substrate containing the composite solid electrolyte layer by its own drive.

[0118] The substrate containing the recovered composite solid electrolyte layer can be used as is, or the composite solid electrolyte can be used in the form of a free-standing film by additionally performing the step of separating the composite solid electrolyte layer from the substrate.

[0119] The term "freestanding film" refers to a film that can maintain its film form on its own at room temperature and pressure without a separate support, that is, without a substrate.

[0120] In the manufacturing method of the embodiment described above, steps (S1) to (S6) may be carried out continuously, so that the composite solid electrolyte can be manufactured in a continuous process.

[0121] Composite solid electrolyte The composite solid electrolyte produced by the above-described embodiment comprises a polymer including a PEO (polyethylene oxide) copolymer containing crosslinkable functional groups; a ceramic compound; and a polar compound, wherein at least a portion of the crosslinkable functional groups form crosslink bonds with each other, so that the polymer forms a three-dimensional network structure, and the polar compound may be contained within the three-dimensional network structure in a gaseous state or have a structure bonded to the polymer chain.

[0122] In the composite solid electrolyte, the three-dimensional network structure includes a three-dimensional frame and an internal space formed by the upper frame, wherein the frame includes polymer chains containing crosslinks formed by the crosslinkable functional groups, and the internal space may include a ceramic compound or a polar compound in a gaseous state formed by vapor deposition.

[0123] The crosslinking bonds formed by the crosslinking functional groups forming the frame may include crosslinking bonds between the crosslinking functional groups and / or crosslinking bonds between the crosslinking functional groups and the crosslinking agent.

[0124] By including the ceramic compound in a dispersed form within the internal space of the three-dimensional network structure, uniform dispersion of the ceramic compound is possible. Due to the morphological characteristics of the uniformly dispersed ceramic compound, the mechanical strength and ionic conductivity of the composite solid electrolyte can be further improved.

[0125] Furthermore, the polymer chain may be bonded to a polar compound in a gaseous state, or the internal space of the polymer chain may contain a polar compound in a gaseous state. In this case, the method of bonding the polar compound to the polymer chain is not particularly limited, as long as the polar compound is fixed to the polymer chain. In other words, the term "bonding" can include all types of bonding, such as physical, chemical, and physicochemical bonding.

[0126] Furthermore, the form, structure, types and content of the constituent components of the composite solid electrolyte are as described above.

[0127] All solid state battery An additional embodiment of the invention also relates to an all-solid-state battery comprising the composite solid electrolyte, wherein the all-solid-state battery comprises a negative electrode, a positive electrode, and a composite solid electrolyte interposed between the negative electrode and the positive electrode, the solid electrolyte being manufactured according to the embodiment described above.

[0128] Specifically, the composite solid electrolyte has a three-dimensional network structure of polymer chains as described above, and ceramic compounds are uniformly contained in the internal space of the polymer chains. Through the vapor deposition process, polar compounds, which are gaseous molecules of the polar solvent, are bonded to the polymer chains or contained in the internal space of the polymer chains, improving their mechanical properties and ionic conductivity, making them suitable as an electrolyte for all-solid-state batteries.

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

[0130] The positive electrode active material layer comprises a positive electrode active material, a binder, and a conductive material.

[0131] Furthermore, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly intercalating and releasing lithium ions, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v ]O2(wherein M is one or more elements selected from the group consisting of Al, Ga, and In; 0.3≦x<1.0, 0≦y, z≦0.5, 0≦v≦0.1, x+y+z+v=1), Li(Li a M b-a-b’ M' b’ )O 2-c A c Layered compounds such as (wherein 0≦a≦0.2, 0.6≦b≦1, 0≦b'≦0.2, and 0≦c≦0.2; M comprises Mn and one or more selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M' is one or more selected from the group consisting of Al, Mg, and B, and A is one or more selected from the group consisting of P, F, S, and N) or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0-0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented as MyO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y = 0.01-0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented as O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta, and y = 0.01-0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc., are examples, but are not limited to these.

[0132] Furthermore, the positive electrode active material may be present in an amount of 40 to 80% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 40% or more by weight, 50% or more by weight, or 70% or less by weight, or 80% or less by weight. If the content of the positive electrode active material is less than 40% by weight, the connectivity between the positive electrode active materials may be insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0133] Furthermore, the binder is a component that assists in the bonding of the positive electrode active material to conductive materials and to the current collector, and includes styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylo The binder may include one or more selected from the group consisting of nitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0134] Furthermore, the binder may be present in an amount of 1% to 30% by weight based on the total weight of the positive electrode active material layer. Specifically, the binder content may be 1% or more by weight, 3% or more by weight, 15% or less by weight, or 30% or less by weight. If the binder content is less than 1% by weight, the adhesive strength between the positive electrode active material and the positive electrode current collector may decrease. If it exceeds 30% by weight, the adhesive strength will improve, but the amount of positive electrode active material will decrease accordingly, which may reduce the battery capacity.

[0135] Furthermore, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery and has excellent electrical conductivity without inducing chemical changes in the battery. Typically, graphite or conductive carbon can be used, for example, 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, and lamp black; carbon-based materials whose crystalline structure is graphene or graphite; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum powder and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which can be used alone or in mixtures of two or more, but are not necessarily limited to these.

[0136] The conductive material may typically be present in an amount of 0.5% to 30% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 0.5% or more by weight, 1% or more by weight, 20% or less by weight, or 30% or less by weight. If the content of the conductive material is excessively low, less than 0.5% by weight, it may be difficult to expect an improvement in electrical conductivity, or the electrochemical properties of the battery may deteriorate. If it is excessively high, exceeding 30% by weight, the amount of positive electrode active material may be relatively reduced, leading to a decrease in capacity and energy density. The method for incorporating the conductive material into the positive electrode is not significantly limited, and conventional methods known in the art, such as coating the positive electrode active material, can be used.

[0137] Furthermore, the positive electrode current collector supports the positive electrode active material layer and plays a role in transferring electrons between the external conductor and the positive electrode active material layer.

[0138] The positive electrode current collector is not particularly limited as long as it has high electronic conductivity without inducing chemical changes in the all-solid-state battery. For example, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., and aluminum-cadmium alloys can be used as the positive electrode current collector.

[0139] The positive electrode current collector may have a fine uneven surface or a three-dimensional porous structure to enhance the bonding force with the positive electrode active material layer. This allows the positive electrode current collector to take on a variety of forms, such as film, sheet, foil, mesh, net, porous material, foam, or nonwoven fabric.

[0140] Such positive electrodes can be manufactured by conventional methods. Specifically, 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 applied to a positive electrode current collector and dried, and then selectively compressed and molded onto the current collector to improve electrode density. In this case, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive material and that evaporates easily. Examples include acetonitrile, methanol, ethanol, tetrahydrofuran, water, and isopropyl alcohol.

[0141] On the other hand, the negative electrode included in the all-solid-state battery may include a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of the negative electrode current collector.

[0142] The negative electrode active material is lithium (Li +This may include materials that can be reversibly intercalated or deintercalated, materials that can react with lithium ions to reversibly form lithium-containing compounds, lithium metals, or lithium alloys.

[0143] The aforementioned lithium ion (Li + The material from which the lithium ion (Li) can be reversibly inserted or removed may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + A substance capable of reversibly forming a lithium-containing compound by reacting with ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) with a metal selected from the group consisting of 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).

[0144] Preferably, the negative electrode active material may be lithium metal, and more specifically, it may be in the form of a lithium metal thin film or lithium metal powder.

[0145] The negative electrode active material may be present in an amount of 40 to 80% by weight based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40% or more by weight, 50% or more by weight, or 70% or less by weight, or 80% or less by weight. If the content of the negative electrode active material is less than 40% by weight, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0146] Furthermore, the binder in the positive electrode active material layer is as described above.

[0147] Furthermore, the conductive material is as described above in the positive electrode active material layer.

[0148] Furthermore, the negative electrode current collector is not particularly limited as long as it is conductive without inducing a chemical change in the battery. For example, the negative electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. In addition, the negative electrode current collector can be made of various forms such as films, sheets, foils, nets, porous materials, foams, and nonwoven fabrics with fine irregularities formed on their surface, similar to the positive electrode current collector.

[0149] The method for manufacturing the negative electrode is not particularly limited, and it can be manufactured by forming a negative electrode active material layer on a negative electrode current collector using methods for forming layers or films commonly used in the industry. For example, methods such as crimping, coating, or vapor deposition may be used. Furthermore, the negative electrode of the present invention is also included in the case where a metallic lithium thin film is formed on a metal plate by initial charging after the battery has been assembled without a lithium thin film on the negative electrode current collector.

[0150] Furthermore, according to an additional embodiment of the invention, a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source are provided.

[0151] Specific examples of the aforementioned devices include, but are not limited to, power tools powered by battery-powered motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0152] The following examples are provided to facilitate understanding of the invention, but these examples are provided only to make the invention easier to understand, and the invention is not limited thereto.

[0153] In the following examples and comparative examples, polymers containing copolymers and polymer solid electrolytes containing organic solvents were produced, as shown in Table 1 below.

[0154] Examples Example 1: Production of a composite solid electrolyte 1) Production of mixed solution A polyethylene oxide (PEO) copolymer of the following chemical formula 1a was prepared: [Chemical formula 1a] [ka] In the above chemical formula 1a, R1 is -CH2-O-(CH2-CH2-O) k The copolymer is -CH3, R2 is -CH2-O-CH2-CH=CH2, k is 2, the l:m:n ratio is 85:13:2, and the weight-average molecular weight (Mw) of the copolymer is approximately 2,000,000 g / mol.

[0155] The copolymer of chemical formula 1a has an allyl group linked via a methylene oxide linker as a crosslinking functional group.

[0156] A mixed solution of the polyethylene oxide copolymer and ceramic compound was prepared by mixing the polyethylene oxide copolymer with acetonitrile as the solvent, trimethylolpropane trimethacrylate as a crosslinking agent, benzoyl peroxide as an initiator, LiTFSI as a lithium salt, and LSTP as a ceramic compound. This solution was then stirred for 24 hours using a magnetic bar. At this time, the composition of the mixed solution of polyethylene oxide copolymer and ceramic compound was prepared by mixing 100 parts by weight of polyethylene oxide copolymer with 20 parts by weight of the crosslinking agent trimethylolpropane trimethacrylate, 1 part by weight of the initiator benzoyl peroxide, 36 parts by weight of the lithium salt LiTFSI, and 40 parts by weight of the ceramic compound LSTP. The concentration of the polyethylene oxide copolymer in the mixed solution was 11.1% by weight, and the concentration of the polyethylene oxide copolymer and ceramic compound was 14.9% by weight using acetonitrile solvent.

[0157] (2-stage) Supply of substrate A rewinding machine supplied the SUS foil base film to a unidirectional transport path.

[0158] 3-step process: Formation of the coated film After the mixed solution was placed in a mixer, it was applied to a SUS foil, which is a base film supplied to a unidirectional transfer path by a rewinding machine, using a solution casting method to form a coated film.

[0159] 4-stage polymer film manufacturing The coating film formed on the substrate film, supplied to a unidirectional transfer path by the aforementioned rewinding machine, was transferred to a drying section, where it was primary dried at room temperature for 12 hours, followed by secondary drying at 100°C for 3 hours to produce a polymer film with a thickness of 200 μm.

[0160] 5-step process) Manufacturing of composite solid electrolytes after vapor deposition The polymer film was transferred to the deposition section and deposition was carried out.

[0161] The aforementioned deposition process involved filling the lower part of the chamber in the deposition section with EMC (ethyl methyl carbonate) solvent, allowing it to evaporate naturally at room temperature for 72 hours, and then introducing EMC vapor into the polymer film that had been transferred to the upper part of the chamber. This allowed the EMC molecules to bond to the polymer chains inside the polymer film or to be deposited so that they were located within the internal space of the polymer chains, thereby producing a composite solid electrolyte layer.

[0162] 6-step process: Manufacturing of composite solid electrolytes in the form of freestanding films. The substrate film containing the manufactured composite solid electrolyte layer was wound up using a rewinder and recovered. Thereafter, the substrate film was peeled off to produce a composite solid electrolyte in the form of a freestanding film.

[0163] Comparative example: Comparative Example 1: A composite solid electrolyte containing only modified PEO (no liquid). The composite solid electrolyte was manufactured in the same manner as in Example 1, except that step 5) of Example 1, in which the EMC solvent is deposited, was omitted.

[0164] Comparative Example 2: A composite solid electrolyte containing a large amount of modified PEO+ liquid. The composite solid electrolyte was manufactured in the same manner as in Example 1, except that the EMC solvent was directly injected into the composite solid electrolyte manufactured in step 1) of Example 1.

[0165] Comparative Example 3: A composite solid electrolyte prepared by depositing unmodified PEO + ceramic compound + organic solvent. A composite solid electrolyte was prepared in the same manner as in Example 1, except that a polyethylene oxide (PEO) monopolymer (weight-average molecular weight: approximately 4,000,000 g / mol) without substituted crosslinking functional groups was used, and no crosslinking agent or initiator was added.

[0166] Comparative Example 4: Modified PEO + Organic Solvent Deposited Polymer Solid Electrolyte A solid electrolyte was prepared in the same manner as in Example 1, except that no ceramic compound was added.

[0167] Experimental example Experimental Example 1: Measurement of Polar Compound Content The content of polar compounds can be measured by monitoring the weight of the liquid phase that evaporates over time while heating a solid electrolyte test specimen using a balance. For example, a heated electronic balance (AND's MS-70) can be used to measure the content by monitoring the weight of the liquid phase that evaporates over time while heating the test specimen at a temperature of 55-70°C or 60°C. When the amount of polar compounds that evaporate over time reaches a saturation point, that saturation point is considered to be the total amount of polar compounds contained within the solid electrolyte. In the examples and comparative examples, the polar compound may be ethyl methyl carbonate (EMC).

[0168] Experimental Example 2: Measurement of Ionic Conductivity of Composite (or Polymer) Solid Electrolytes To measure the ionic conductivity of the solid electrolytes in film form produced in the examples and comparative examples, 1.7671 cm² was used. 2 After forming the solid electrolyte on the lower substrate of a coin cell of a certain size, a coin cell for ionic conductivity measurement was manufactured using SUS as an inert electrode (blocking electrode).

[0169] Using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument), the resistance was measured at 25°C with an amplitude of 10mV and a scan range from 1Hz to 0.1MHz. The ionic conductivity of the solid electrolyte was then calculated using Equation 1 below.

[0170] [Formula 1]

number

[0171] Table 1 below shows the measured EMC content and ionic conductivity of composite (or polymer) solid electrolytes that have been deposited (or contained) in them.

[0172] [Table 1]

[0173] Referring to Table 1 above, it was confirmed that the continuously manufactured composite solid electrolytes of the examples exhibited superior ionic conductivity compared to the solid electrolytes of the comparative examples.

Claims

1. (S1) A step of preparing a mixed solution containing a PEO (polyethylene oxide) copolymer containing a crosslinking functional group and a ceramic compound; (S2) The step of unwinding the substrate using an unwinder and supplying it to the transport path; (S3) A step of applying the mixed solution onto the substrate to form a coating film; (S4) A step in which the substrate on which the coating film has been formed is transferred to a drying section and dried to form a polymer film; (S5) A step of transferring the polymer film to the deposition section and depositing a polar solvent to form a composite solid electrolyte layer; and (S6) A step of winding and recovering the substrate containing the composite solid electrolyte layer using a rewinder; The gas molecules of the aforementioned polar solvent are polar compounds. The content of the polar compound is 0.1% by weight or more and less than 10% by weight on a total weight basis of the composite solid electrolyte. A method for producing a composite solid electrolyte.

2. The method for producing a composite solid electrolyte according to claim 1, wherein the mixed solution in step (S1) further comprises one or more selected from the group consisting of lithium salts, crosslinking agents, and initiators.

3. The method for producing a composite solid electrolyte according to claim 1, wherein the mixed solution contains 10 to 100 parts by weight of the ceramic compound per 100 parts by weight of the PEO (polyethylene oxide) copolymer.

4. The method for producing a composite solid electrolyte according to claim 1, wherein the deposition in step (S5) involves naturally evaporating the polar solvent at room temperature or evaporating it by heating to incorporate gaseous molecules of the polar solvent into the surface or interior of the polymer chains of the PEO copolymer.

5. The crosslinkable functional group is bonded to the PEO copolymer via an alkylene linker or alkylene oxide linker having 0 to 10 carbon atoms (wherein the alkylene linker having 0 carbon atoms shows a single bond). A method for producing a composite solid electrolyte according to claim 1, wherein the group consists of one or more selected from the group consisting of hydroxyl groups, carboxyl groups, isocyanate groups, nitro groups, cyano groups, amine groups, amide groups, epoxy groups, and allyl groups.

6. The method for producing a composite solid electrolyte according to claim 1, wherein the PEO (polyethylene oxide) copolymer is a copolymer containing repeating units of the following chemical formulas 1 to 3: [Chemical formula 1] 【Chemistry 1】 [Chemical formula 2] 【Chemistry 2】 [Chemical formula 3] 【Transformation 3】 In the above chemical formulas 1 to 3, R １ is, -CH ２ -O-(CH ２ -CH ２ -O)k-R ３ This shows that k is between 0 and 20, and R ３ This represents an alkyl group having 1 to 5 carbon atoms. R ２ This refers to a substituent in which one or more crosslinking functional groups selected from the group consisting of hydroxyl groups, carboxyl groups, isocyanate groups, nitro groups, cyano groups, amine groups, amide groups, epoxy groups, and allyl groups are bonded to the polymer chain via a C0-C10 alkylene linker or alkylene oxide linker (where the C0 alkylene linker shows a single bond). l, m, and n are the number of repetitions in the repeating unit, where l and n are independent integers between 1 and 1000, and m is an integer between 0 and 1000.

7. The method for producing a composite solid electrolyte according to claim 1, wherein the polar solvent comprises one or more selected from the group consisting of carbonate compounds and sulfonyl compounds.

8. The method for producing a composite solid electrolyte according to claim 1, wherein the polar solvent comprises one or more selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), and sulfolane.

9. The method for producing a composite solid electrolyte according to claim 1, wherein the ceramic compound comprises one or more 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) compounds.

10. A method for producing a composite solid electrolyte according to claim 1, wherein steps (S1) to (S6) are carried out continuously.

11. The method for producing a composite solid electrolyte according to claim 1, wherein the composite solid electrolyte layer does not contain the polar solvent in a liquid state.

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