Polymer Solid Electrolyte and Method for Producing the Same

Abstract

The present invention relates to a polymer solid electrolyte and a method for producing the same.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0066984 filed on May 31, 2022 and Korean Patent Application No. 10-2023-0070168 filed on May 31, 2023, and includes all the contents disclosed in the documents of the Korean patent applications as part of this specification.

[0002] The present invention relates to a polymer solid electrolyte and a method for manufacturing the same.

Background Art

[0003] In a lithium secondary battery using a liquid electrolyte, since the negative electrode and the positive electrode are partitioned by a separator, if the separator is damaged due to deformation or an external impact, a short circuit may occur, which may lead to risks such as overheating or explosion. Therefore, the development of a solid electrolyte that can ensure safety in the field of lithium secondary batteries is a very important issue.

[0004] A lithium secondary battery using a solid electrolyte has advantages such as increased battery safety, prevention of electrolyte leakage, improved battery reliability, and easy fabrication of thin batteries. In addition, since lithium metal can be used for the negative electrode, the energy density can be improved, and it is expected to be applied to high-capacity secondary batteries for electric vehicles as well as small secondary batteries, and is attracting attention as a next-generation battery.

[0005] Among solid electrolytes, as raw materials for polymer solid electrolytes, polymer materials with ion-conductive properties can be used, and hybrid materials in which a polymer material and an inorganic material are mixed have also been proposed. As the inorganic material, inorganic materials such as oxides or sulfides can be used.

[0006] Such conventional polymer solid electrolytes were manufactured through a process of high-temperature drying after forming a coating film. However, the manufacturing technology of conventional polymer solid electrolytes has a limitation in that it is difficult to manufacture a polymer solid electrolyte with improved ionic conductivity due to the high crystallinity of crystalline polymers or semi-crystalline polymers. That is, the higher the crystallinity of the polymer, the lower the chain mobility of the polymer chains. As a result, there are restrictions on the movement of lithium ions within the polymer solid electrolyte, making it difficult to improve the ionic conductivity of the polymer solid electrolyte.

[0007] For example, conventional polymer solid electrolytes can be manufactured by using polyvinyl alcohol (PVA) containing a hydroxyl group, which is a cross-linkable functional group as a polymer, forming a coating film, and then going through a high-temperature drying process. Specifically, after dissolving the PVA in water to produce an aqueous PVA solution, the aqueous PVA solution is applied onto a substrate by solution casting to form a coating film, and then dried at room temperature or high temperature to produce a polymer solid electrolyte in the form of a PVA film. At this time, the high temperature can mean 80°C or higher, which is the glass transition temperature (Tg) of PVA. In the drying process, after the moisture evaporates, hydrogen bonds are formed between the cross-linkable functional groups contained in PVA, and due to these hydrogen bonds, chain folding of the polymer chains occurs, and a phenomenon of increasing crystallinity of the polymer film appears. The higher the crystallinity, the more brittle the polymer film formed. In a polymer film with high crystallinity and brittleness, the chain mobility of the polymer chains decreases, and when there are dissociated ions inside the polymer film, the ion mobility also significantly decreases. As a result, a general PVA film manufactured by the process of forming a coating film and then high-temperature drying as described above exhibits physical properties that are not suitable as a polymer solid electrolyte for lithium secondary batteries.

[0008] To overcome such limitations of conventional polymer solid electrolytes, a technique has been developed in which a plasticizer is added to a crystalline polymer or semi-crystalline polymer to improve the mobility of polymer chains and enhance the ionic conductivity of the polymer solid electrolyte. However, when using a plasticizer, it may be difficult to set process conditions because an appropriate degree of dispersion and miscibility between the polymer and the plasticizer must be ensured. In addition, when applying a liquid plasticizer, the compatibility with the polymer may decrease, and it may be difficult to carry out the manufacturing process of the polymer solid electrolyte.

[0009] Therefore, there is a need to develop a technique that can improve the ionic conductivity of polymer solid electrolytes without using a separate additive such as a plasticizer.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide a polymer solid electrolyte with improved ionic conductivity.

[0012] Another object of the present invention is to provide a method for manufacturing a polymer solid electrolyte with improved ionic conductivity.

[0013] Another object of the present invention is to provide an all-solid-state battery including a polymer solid electrolyte with improved ionic conductivity.

Means for Solving the Problems

[0014] To achieve the above object, The present invention provides a polymer solid electrolyte comprising a polymer containing a crosslinkable functional group (side chain), a lithium salt, and a solvent comprising a first solvent and a second solvent, wherein the polymer solid electrolyte comprises a crosslinked structure and an amorphous polymer chain containing the crosslinkable functional group, and the crosslinked structure comprises (a) a crosslink between crosslinkable functional groups, (b) a crosslink between a crosslinkable functional group and the first solvent, and (c) a bond between a crosslinkable functional group and the lithium salt.

[0015] The present invention also provides a method for producing a polymer solid electrolyte, comprising: (S1) adding a lithium salt to a solution comprising a polymer containing a crosslinkable functional group and a first solvent to produce a solution for forming a polymer solid electrolyte; (S2) coating the solution for forming a polymer solid electrolyte onto a substrate to form a coating film; (S3) freezing and thawing the coating film to form a crosslinked structure of the polymer containing the crosslinkable functional group, wherein the crosslinked structure of the polymer comprises the lithium salt and the first solvent, to produce a first polymer solid electrolyte; and (S4) replacing the first solvent in the first polymer solid electrolyte with a second solvent to produce a second polymer solid electrolyte.

[0016] The present invention also provides an all-solid-state battery comprising the polymer solid electrolyte.

Advantages of the Invention

[0017] The polymer solid electrolyte according to the present invention has a structure comprising a crosslinked structure and an amorphous polymer chain formed by crosslinkable functional groups contained in the polymer, which reduces the crystallinity of the polymer and thereby improves the ionic conductivity.

[0018] In addition, due to the above structural characteristics, the polymer solid electrolyte exhibits physical properties with reduced brittleness, increased ductility and viscosity.

[0019] In addition, the polymer solid electrolyte can improve the ionic conductivity of the polymer solid electrolyte through solvent exchange.

Mode for Carrying Out the Invention

[0020] Hereinafter, in order to facilitate the understanding of the present invention, the present invention will be described in more detail.

[0021] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of the terms in order to explain his own invention in the best way, they must be construed in accordance with the meanings and concepts corresponding to the technical idea of the present invention.

[0022] As used herein, the term "crosslinked structure" means a three-dimensional frame formed by polymer chains and a structure including the internal space of the frame. The polymer chains may be formed by crosslinks including crosslinkable functional groups contained in the polymer. Since the crosslinked structure has a three-dimensional shape and the polymer chains are intertwined with each other, it can also be referred to as a three-dimensional network structure. Polymer solid electrolyte The polymer solid electrolyte of the present invention is a polymer solid electrolyte including a polymer containing a crosslinkable functional group, a lithium salt, and a solvent including a first solvent and a second solvent. The polymer solid electrolyte includes a crosslinked structure and an amorphous polymer chain containing the crosslinkable functional group. The crosslinked structure may include (a) a crosslink between crosslinkable functional groups, (b) a crosslink between a crosslinkable functional group and the first solvent, and (c) a bond between a crosslinkable functional group and the lithium salt.

[0023] In the present invention, the crosslink between the crosslinkable functional groups in (a) may include a hydrogen bond between the crosslinkable functional groups. For example, the hydrogen bond may be a hydrogen bond between OH-.

[0024] If the crosslinked structure consists only of crosslinks between the (a) crosslinkable functional groups, crystallinity of the polymer solid electrolyte may occur, and ionic conductivity may decrease.

[0025] However, since the crosslinked structure includes not only crosslinks between the (a) crosslinkable functional groups but also crosslinks between the (b) crosslinkable functional groups and the first solvent and bonds between the (c) crosslinkable functional groups and the lithium salt, it is possible to prevent the crystallinity of the polymer solid electrolyte from occurring.

[0026] In the present invention, the crosslink between the (b) crosslinkable functional group and the first solvent may include a hydrogen bond. For example, the hydrogen bond may be a hydrogen bond between OH− and H+. At this time, H+ may be derived from an aqueous solvent.

[0027] The crosslink between the (b) crosslinkable functional group and the first solvent may mean a hydrogen bond between a part of the solvent remaining in the freezing and thawing processes and the crosslinkable functional group.

[0028] Also, the crosslink between the (b) crosslinkable functional group and the first solvent interferes with the crosslink between the (a) crosslinkable functional groups, so that the crosslinked structure is not composed only of the crosslink between the (a) crosslinkable functional groups, and it is possible to prevent an increase in the crystallinity of the polymer solid electrolyte.

[0029] In the present invention, the bond between the (c) crosslinkable functional group and the lithium salt may include a bond by Lewis acid-base interaction. For example, the bond may be a bond between OH− and Li+.

[0030] The bond between the (c) crosslinkable functional group and the lithium salt is a bond by Lewis acid-base interaction and may be a bond in a form such as a metal-ligand bond.

[0031] In addition, the bond between the (c) crosslinkable functional group and the lithium salt prevents the crosslinking between the (a) crosslinkable functional groups and the crosslinking between the (b) crosslinkable functional group and the first solvent, so that the crosslinked structure is not composed only of the crosslinking between the (a) crosslinkable functional groups, thereby preventing the generation of crystallinity of the polymer solid electrolyte and simultaneously promoting the formation of amorphous polymer chains. As the amorphous polymer chains are formed, the mobility of the polymer chains is improved, so that the hopping effect of the lithium ions is increased, and the ionic conductivity of the polymer solid electrolyte can be improved.

[0032] In the present invention, the amorphous polymer chains can also be formed in a freezing process as described below, and do not form crystals due to regular folding of the polymer chains, meaning polymer chains that exist in a freely behaving state. That is, the amorphous polymer chains may include a polymer containing a crosslinkable functional group that does not form bonds such as the (a), (b), and (c).

[0033] Due to the crosslinked structure, the polymer solid electrolyte is not easily cut or broken, and can serve as an electrolyte support that stably contains lithium ions.

[0034] In addition, due to the amorphous polymer chains, the polymer solid electrolyte exhibits elasticity, can minimize brittleness, which is the property of being easily broken, has excellent polymer chain mobility, and the mobility of lithium ions inside the electrolyte is improved, so that a polymer solid electrolyte with improved ionic conductivity can be provided.

[0035] In the present invention, the crosslinkable functional groups contained in the polymer containing the crosslinkable functional groups can have the property of forming a crosslinked structure by forming bonds such as the (a), (b), and (c).

[0036] For example, the crosslinkable functional group can include one or more selected from the group consisting of a hydroxyl group, a carboxyl group, and an amide group.

[0037] Also, the weight average molecular weight (Mw) of the polymer containing the crosslinkable functional group may be 80,000 g / mol to 130,000 g / mol. Specifically, it may be 80,000 g / mol or more, 83,000 g / mol or more, or 85,000 g / mol or more, and may also be 90,000 g / mol or less, 110,000 g / mol or less, or 130,000 g / mol or less. When the weight average molecular weight (Mw) of the polymer containing the crosslinkable functional group is less than 80,000 g / mol, the bonding by the crosslinkable functional group may not be sufficiently formed to obtain a crosslinked structure. When the weight average molecular weight (Mw) of the polymer containing the crosslinkable functional group exceeds 130,000 g / mol, the entanglement of polymer chains increases in the polymer solution used in the manufacturing process, and the solvent penetration rate into the polymer chains decreases. As a result, the gelation of the polymer is accelerated, the solubility of the polymer decreases, the bonding by the crosslinkable functional group is not smoothly performed, and the formation of the crosslinked structure may not be easy.

[0038] Further, the polymer containing the crosslinkable functional group may have a characteristic that phase separation between the polymer and the solvent is smoothly performed in the polymer solution used in the manufacturing process, and the bonds (a), (b), and (c) are well formed by the crosslinkable functional groups contained in the phase-separated polymer during freezing.

[0039] For example, the polymer containing the crosslinkable functional group may include one or more selected from the group consisting of polyvinyl alcohol (PVA), gelatin, methylcellulose, agar, dextran, poly(vinyl pyrrolidone), poly(acryl amide), poly(acrylic acid) (PAA), starch-carboxymethyl cellulose, hyaluronic acid-methylcellulose, chitosan, poly(N-isopropylacrylamide), and amino-terminated PEG. Desirably, the polymer containing the crosslinkable functional group may be PVA. In the process of manufacturing the polymer solid electrolyte, PVA can efficiently perform phase separation between PVA and the solvent during freezing, which may be advantageous for forming a crosslinked structure by the (a), (b), and (c) bonds derived from the crosslinkable functional groups of PVA phase-separated from the solvent.

[0040] In the present invention, the lithium salt is contained in a dissociated state in the internal space of the crosslinked structure, and can improve the ionic conductivity of the polymer solid electrolyte.

[0041] In addition, the lithium salt can form a bond between the (c) crosslinkable functional group and the lithium salt, prevent the generation of crystallinity of the polymer solid electrolyte, and simultaneously promote the formation of an amorphous polymer chain.

[0042] The lithium salt may include one or more selected from the group consisting of (CF3SO2)2NLi (lithium bis(trifluoromethanesulphonyl)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, and LiC(CF3SO2)3.

[0043] In the present invention, the molar ratio ([Li] / [G]) of lithium ([Li]) of the lithium salt to the crosslinkable functional group ([G]) of the polymer containing the crosslinkable functional group contained in the polymer solid electrolyte may be more than 0.1 and less than 0.5. Specifically, it may be more than 0.1, 0.2 or more, or 0.3 or more, and may be 0.4 or less or less than 0.5. When the molar ratio ([Li] / [G]) is 0.1 or less, the content of the lithium salt may decrease, and the ionic conductivity of the polymer solid electrolyte may decrease. When it is 0.5 or more, the content of the polymer containing the crosslinkable functional group may decrease, and the (a), (b), and (c) bonds may not be sufficiently formed, resulting in increased crystallinity and possible decrease in ionic conductivity. When the crosslinkable functional group is a hydroxyl group (OH-), [G] can be represented as [OH] or [O].

[0044] In one embodiment of the present invention, the solvent is contained inside the crosslinked structure formed by the physical crosslinking of the polymer solid electrolyte, the solvent exchange process is easy, and the ionic conductivity of the polymer solid electrolyte can be improved.

[0045] The solvent may include a first solvent and a second solvent.

[0046] The first solvent and the second solvent are solvents that are separated from each other, and their solubilities in the polymer containing the crosslinkable functional group may be different.

[0047] The first solvent has a high solubility in the polymer containing the crosslinkable functional group and can form a crosslinked structure with the polymer containing the crosslinkable functional group. On the other hand, the second solvent has a low solubility in the polymer containing the crosslinkable functional group and it is difficult to form a crosslinked structure with the polymer containing the crosslinkable functional group.

[0048] Also, the first solvent and the second solvent may be solvents that are separated from each other as an aqueous electrolyte or a non-aqueous electrolyte according to the battery structure.

[0049] Also, the first solvent and the second solvent may be solvents that are separated from each other by a flame-retardant electrolyte.

[0050] The first solvent may be any one selected from the group consisting of water, ethanol, isopropyl alcohol, dimethyl sulfoxide, acetonitrile, NMP, a co-solvent obtained by mixing water and alcohols, and a co-solvent obtained by mixing water and dimethyl sulfoxide.

[0051] The boiling point of the first solvent may be 150°C or lower. The boiling point of the first solvent may be lower than the boiling point of the second solvent. When the boiling point of the first solvent exceeds 150°C, during the removal process of the first solvent, hydrogen bonds and Lewis acid-base interaction forces formed inside the polymer may collapse, and the mechanical properties of the polymer solid electrolyte may be greatly reduced.

[0052] The first solvent can form a cross-linked structure through a freezing / thawing process after dissolving a polymer containing a cross-linkable functional group. For example, when the first solvent is water, phase separation with the polymer containing a cross-linkable functional group occurs significantly during the freezing process, forming an ice phase and a rich phase of the polymer containing a cross-linkable functional group.

[0053] Replacing the first solvent with the second solvent is for using the polymer solid electrolyte according to the present invention in the chemistry of a battery vulnerable to water. For example, when water is used as the first solvent, there is no problem in the chemistry of a battery where the characteristics do not deteriorate due to an aqueous electrolyte, but in the chemistry of a battery vulnerable to water, there are problems such as a decrease in battery performance or the battery not operating. To solve such problems, by removing the first solvent and replacing it with a second solvent that can be used inside the battery without loss of ionic conductivity, a polymer solid electrolyte capable of stable battery driving can be provided.

[0054] Also, when the first solvent is used, there is no problem in the production of the solid electrolyte, but since the solvent is vulnerable to combustion during a battery fire or explosion, there may be a problem of inducing greater damage. To solve such problems, by removing the first solvent and replacing it with a second solvent having flame-retardant properties, a polymer solid electrolyte capable of stable battery driving can be provided.

[0055] Also, when the first solvent is used, there is no problem in the production of the solid electrolyte, but when the first solvent is applied as an electrolyte inside the battery, there may be a problem of reducing the product life due to unexpected side reactions and decomposition of the solvent during battery driving. To solve such problems, by removing the first solvent and replacing it with a stable second solvent from side reactions with the solvent, etc., a polymer solid electrolyte capable of stable battery driving can be provided.

[0056] The second solvent may contain one or more selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), dioxolane (DOX), dimethoxyethane (DME), diethoxyethane (DEE), γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane, or may include combinations thereof. For example, it may include EC:EMC (1:3), EC:EMC (1:1), EC:DMC:EMC:FEC (3:3:3:1), etc., but is not limited to only these examples.

[0057] The content of the first solvent in the polymer solid electrolyte may be 1 to 1000 ppm. When the content of the first solvent exceeds 1000 ppm, it inhibits the absorption of the second solvent, and there are problems such as a decrease in physical properties expected from the second solvent, for example, a decrease in ionic conductivity or a reduction in the stability of the battery.

[0058] In the present invention, the polymer solid electrolyte may be in the form of a free-standing film or a coating layer. The free-standing film means a film that can maintain its film form by itself without a separate support at normal temperature and pressure. The coating layer means a layer obtained by coating on a substrate. When the polymer solid electrolyte is in the form of a coating layer, the coating layer may be in the form of a layer coated on an electrode.

[0059] The free-standing film or coating layer may exhibit elasticity and minimize brittleness, and has the characteristics of a support for stably containing lithium ions, so it may be in a form suitable as a polymer solid electrolyte.

[0060] In the present invention, the ionic conductivity of the polymer solid electrolyte may be 10 -4 S / cm or more.

[0061] Due to the structural characteristics including the crosslinked bond structure as described above, the polymer solid electrolyte has low crystallinity and improved ionic conductivity. Therefore, despite being a solid electrolyte, it exhibits an ionic conductivity equal to or higher than that of conventional liquid electrolytes, and the performance of all-solid-state batteries can be improved.

[0062] Method for producing polymer solid electrolyte The method for producing a polymer solid electrolyte according to an embodiment of the present invention may include the following steps: (S1) Adding a lithium salt to a solution containing a polymer having a crosslinkable functional group and a first solvent to produce a solution for forming a polymer solid electrolyte; (S2) Coating the solution for forming the polymer solid electrolyte on a substrate to form a coating film; (S3) Freezing and thawing the coating film to form a crosslinked bond structure of the polymer having the crosslinkable functional group, and the crosslinked bond structure of the polymer includes the first polymer solid electrolyte containing the lithium salt and the first solvent; (S4) Exchanging the first solvent in the first polymer solid electrolyte with a second solvent to produce a second polymer solid electrolyte.

[0063] In the method for producing the polymer solid electrolyte, a plasticizer used to reduce the crystallinity of the polymer is not added. Through the freezing process, crosslinking between (a) crosslinkable functional groups, (b) crosslinking between the crosslinkable functional group and the first solvent, and (c) binding between the crosslinkable functional group and the lithium salt induced by the crosslinkable functional groups contained in the polymer can be induced, thereby preventing the crystallization of the polymer. As a result, a polymer solid electrolyte with improved ionic conductivity can be produced. Hereinafter, the method for producing a polymer solid electrolyte according to the present invention will be described in more detail for each step.

[0064] In one embodiment of the present invention, in the step (S1), a lithium salt can be added to a solution containing a polymer having a crosslinkable functional group and a first solvent to produce a solution for forming a polymer solid electrolyte.

[0065] The polymer, the first solvent, and the lithium salt are as described above.

[0066] The concentration of the polymer solution containing the crosslinkable functional group can be appropriately adjusted in consideration of the degree to which the coating process can proceed smoothly when the solution for forming the polymer solid electrolyte is applied to a substrate. For example, the concentration of the polymer solution containing the crosslinkable functional group may be 5% to 20%, specifically, it may be 5% or more, 7% or more, or 9% or more, and may also be 13% or less, 17% or less, or 20% or less. When the concentration of the polymer solution containing the crosslinkable functional group is less than 5%, the concentration is excessively dilute and may flow off when applied onto the substrate. When it exceeds 20%, it is difficult to dissolve a lithium salt with a desired concentration in the polymer solution, and due to the high viscosity, it may be difficult to apply it in the form of a uniform thin film.

[0067] In one embodiment of the present invention, in the step (S2), the solution for forming the polymer solid electrolyte can be applied onto a substrate to form a coating film.

[0068] The substrate is not particularly limited as long as it can serve as a support on which the solution for forming the polymer solid electrolyte is applied. For example, the substrate may be stainless steel (SS), a polyethylene terephthalate film, a polytetrafluoroethylene film, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a vinyl chloride copolymer film, a polyurethane film, an ethylene-vinyl acetate film, an ethylene-propylene copolymer film, an ethylene-ethyl acrylate copolymer film, an ethylene-methyl acrylate copolymer film, or a polyimide film.

[0069] Also, the coating method is not particularly limited as long as it can coat the solution for forming the polymer solid electrolyte on the substrate in the form of a film. 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, or solution casting.

[0070] In one embodiment of the present invention, in the step (S3), the coating film is frozen and thawed to form a crosslinked structure of the polymer containing the crosslinkable functional group, and the crosslinked structure of the polymer can be used to produce a first polymer solid electrolyte containing the lithium salt and the first solvent.

[0071] In the freezing process, the polymer and water contained in the aqueous polymer solution containing the crosslinkable functional group used to form the coating film can undergo phase separation. The phase separation may be induced because the strength of the hydrogen bond between the water molecules is stronger than that between the crosslinkable functional group and the water molecules. The water molecules aggregated by the hydrogen bond between the water molecules exist in the form of ice (ice phase) due to the freezing process. As a result, the number of crosslinkable functional groups forming hydrogen bonds is significantly reduced through the interaction with the water molecules.

[0072] Due to the phase separation, the inside of the coating film is divided into (i) a polymer-poor phase and (ii) a polymer-rich phase.

[0073] The (i) polymer-poor phase contains water molecules aggregated by hydrogen bonds with water molecules and exists in an ice state (ice phase), which can also be said to be in a free water state.

[0074] The (ii) polymer-rich phase is a part containing polymers phase-separated from water. The phase-separated polymers are polymers containing cross-linkable functional groups freed from the interaction with water molecules. After phase separation, they become free and do not form crystals by regular folding, but exist in a relatively freely behaving amorphous state, which is called an amorphous polymer chain.

[0075] Also, a part of the cross-linkable functional groups contained in the phase-separated polymers forms localized crystallites. The localized crystallites act as cross-linkable junction points to form a cross-linked structure including the (a), (b), and (c) bonds.

[0076] Also, in the thawing process after the freezing process, the ice contained in the (i) polymer-poor phase melts and evaporates, and a polymer solid electrolyte with an increased free volume can be produced.

[0077] In addition, the freezing can be appropriately carried out by selecting conditions that can freeze the coating film. For example, the freezing temperature can be in the range of -30°C to -10°C. Specifically, the freezing temperature may be -30°C or higher, -25°C or higher, or -23°C or higher, and may also be -18°C or lower, -15°C or lower, or -10°C or lower. If the freezing temperature is less than -30°C, cracks may occur in the coating film. If it exceeds -10°C, phase separation between the polymer and water may not be sufficiently carried out, and it may be difficult to form an amorphous polymer chain region. In addition, the freezing can be carried out considering a sufficient freezing time within the range of 20 hours to 30 hours.

[0078] In addition, the thawing can be appropriately carried out by selecting conditions that can thaw the frozen coating film to an extent that it can be applied as a polymer solid electrolyte. For example, the thawing temperature may be 15°C to 35°C, or may be room temperature (25°C). If the thawing temperature is less than 15°C, the moisture drying efficiency after thawing (ice melting) may decrease. If it exceeds 35°C, the coating film may shrink and wrinkles or warping may occur.

[0079] As described above, through the freezing and thawing steps, the combination of (a), (b), and (c) is induced, a cross-linked structure is formed, and an amorphous polymer chain can be formed.

[0080] Therefore, the degree of formation of the crosslinked structure can be adjusted by the number of times the freezing and thawing processes are performed. When the process of performing the thawing process after the freezing process is defined as one cycle, the freezing and thawing processes can be performed one cycle or more, two cycles or more, three cycles or more, or five cycles or more. The upper limit value of the cycle is not particularly limited, but it may be ten cycles or less, thirteen cycles or less, or fifteen cycles or less. The more the cycles of the freezing and thawing processes increase within the above range, the more crosslinked structures can be formed, thereby increasing the modulus and strength of the polymer solid electrolyte.

[0081] In one embodiment of the present invention, in the step (S4), the first solvent in the first polymer solid electrolyte can be exchanged with the second solvent to produce the second polymer solid electrolyte.

[0082] The first solvent and the second solvent are as described above.

[0083] The solvent exchange means removing the first solvent in the first polymer solid electrolyte and exchanging it so that the second solvent is mostly present. By the solvent exchange, the second polymer solid electrolyte containing the second solvent can be produced.

[0084] For the solvent exchange, after drying the first solvent contained in the first polymer solid electrolyte at a high temperature, it can be immersed in the second solvent to exchange the first solvent with the second solvent. More specifically, the first polymer solid electrolyte containing the first solvent is placed in a vacuum oven and dried at a low temperature (50 °C) for 6 hours, then dried at a high temperature (100 °C) for 12 hours, and then the dried first solid electrolyte is immersed in the second solvent at room temperature for 24 hours in a dry room environment, whereby the first solvent can be exchanged with the second solvent.

[0085] All-solid-state battery The present invention also relates to an all-solid-state battery including the polymer solid electrolyte, the all-solid-state battery including a negative electrode, a positive electrode, and a polymer solid electrolyte interposed between the negative electrode and the positive electrode, the solid electrolyte having the above-described characteristics.

[0086] Specifically, the polymer solid electrolyte forms physical cross-linking bonds through freezing and thawing processes, resulting in a decrease in crystallinity and an improvement in ionic conductivity through a solvent exchange process, and thus can be suitable as an electrolyte for an all-solid-state battery.

[0087] In the present invention, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of a positive electrode current collector.

[0088] The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material.

[0089] Further, the positive electrode active material is not particularly limited as long as it can reversibly occlude and release lithium ions. For example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v O2 (in the above formula, M is any one selected from the group consisting of Al, Ga, and In or two or more of these elements; 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’ )O 2-c A c (in the above formula, 0 ≦ a ≦ 0.2, 0.6 ≦ b ≦ 1, 0 ≦ b’ ≦ 0.2, 0 ≦ c ≦ 0.2; M includes one or more selected from the group consisting of Mn and 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.). Such layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn2-y O4 (where y is from 0 to 0.33), lithium manganese oxides such as 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 oxides represented by 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 O2 (where M = Co, Ni, Fe, Cr, Zn or Ta and y = 0.01 - 0.1) or lithium manganese composite oxides represented by 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 and the like, but not limited thereto.

[0090] In addition, the positive electrode active material can be contained 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% by weight or more or 50% by weight or more, and may be 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 between the wet positive electrode active material layer and the dry positive electrode active material layer may be insufficient. If it exceeds 80% by weight, the mass transfer resistance may increase.

[0091] In addition, the binder may contain one or more selected from the group consisting of styrene-butadiene rubber, acrylated 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, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl starch, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Desirably, the binder may contain one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethyl cellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0092] In addition, the binder can be contained in an amount of 1% by weight to 30% by weight based on the total weight of the positive electrode active material layer. Specifically, the content of the binder may be 1% by weight or more, or 3% by weight or more, and may be 15% by weight or less, or 30% by weight or less. If the content of the binder is less than 1% by weight, the adhesion between the positive electrode active material and the positive electrode current collector may decrease. If it exceeds 30% by weight, the adhesion improves, but the content of the positive electrode active material decreases accordingly, and the battery capacity may decrease.

[0093] Further, the conductive material is not particularly limited as long as it can prevent side reactions in the internal environment of the all-solid-state battery, does not induce chemical changes in the battery, and has excellent electrical conductivity. Typically, graphite or conductive carbon can be used. For example, graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, denka black, thermal black, channel black, furnace black, lamp black, summer black; carbon-based substances 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; and conductive polymers such as polyphenylene derivatives can be used alone or in combination of two or more, but are not necessarily limited thereto.

[0094] The conductive material can usually be contained in an amount of 0.5% by weight 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% by weight or more, or 1% by weight or more, and may be 20% by weight or less, or 30% by weight or less. If the content of the conductive material is less than 0.5% by weight, it may be difficult to expect an improvement effect in electrical conductivity, or the electrochemical characteristics of the battery may deteriorate. If it exceeds 30% by weight, the amount of the positive electrode active material relatively decreases, and the capacity and energy density may decrease. The method of incorporating the conductive material into the positive electrode is not greatly limited, and ordinary methods known in the art, such as coating on the positive electrode active material, can be used.

[0095] Further, the positive electrode current collector supports the positive electrode active material layer and plays a role in transmitting electrons between the external lead wire and the positive electrode active material layer.

[0096] The positive current collector is not particularly limited as long as it does not induce chemical changes in the all-solid-state battery and has high electronic conductivity. For example, as the positive current collector, copper, stainless steel, aluminum, nickel, titanium, palladium, fired carbon, those obtained by surface treatment with carbon, nickel, silver, etc. on the surface of copper or stainless steel, aluminum-cadmium alloy, etc. can be used.

[0097] In order to strengthen the bonding force with the positive electrode active material layer, the positive current collector can have a fine uneven structure on its surface or adopt a three-dimensional porous structure. As a result, the positive current collector can include various forms such as a film, sheet, foil, mesh, net, porous body, foam, non-woven fabric body, etc.

[0098] The positive electrode as described above can be manufactured according to a normal method. Specifically, a composition for forming a positive electrode active material layer, which is obtained by mixing a positive electrode active material, a conductive material, and a binder on an organic solvent, is applied and dried on a positive current collector, and can be manufactured by selectively compression molding the current collector to improve the electrode density. At this time, as the organic solvent, it is desirable to use one that can uniformly disperse the positive electrode active material, binder, and conductive material and evaporates easily. Specifically, acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, etc. can be mentioned.

[0099] In the present invention, 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 a negative current collector.

[0100] The negative electrode active material can include a material that can reversibly insert (intercalation) or de-insert (deintercalation) lithium (Li+), a material that can react with lithium ions to reversibly form a lithium-containing compound, or lithium metal or a lithium alloy.

[0101] Substances that can reversibly insert or extract lithium ions (Li+) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. Substances that can react with the lithium ions (Li+) 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 a metal selected from the group consisting of lithium (Li) and 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).

[0102] Desirably, the negative electrode active material may be lithium metal, specifically, in the form of a lithium metal thin film or lithium metal powder.

[0103] The negative electrode active material can be contained at 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% by weight or more, or 50% by weight or more, and may be 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 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.

[0104] Also, the binder is as described above in the positive electrode active material layer.

[0105] Also, the conductive material is as described above in the positive electrode active material layer.

[0106] In addition, the negative electrode current collector is not particularly limited as long as it does not induce a chemical change in the battery and has conductivity. For example, the negative electrode current collector can be copper, stainless steel, aluminum, nickel, titanium, fired carbon, or a surface-treated material of copper or stainless steel with carbon, nickel, titanium, silver, etc. on its surface, or an aluminum-cadmium alloy, etc. Also, 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, non-woven fabric body, etc. with fine irregularities formed on its surface.

[0107] The method for manufacturing the negative electrode is not particularly limited, and the negative electrode active material layer can be formed and manufactured using a method for forming a layer or film commonly used in the art on the negative electrode current collector. For example, methods such as pressure bonding, coating, vapor deposition, etc. can be used. Also, when a lithium thin film is not present on the negative electrode current collector and the battery is assembled, and then a metallic lithium thin film is formed on the metal plate by initial charging, it is also included in the negative electrode of the present invention.

[0108] The present invention also provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0109] At this time, specific examples of the device include a power tool powered by a battery motor; electric vehicles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs); electric two-wheel vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; power storage systems, etc., but are not limited thereto. Hereinafter, preferred embodiments are shown to assist in understanding the present invention. However, it is obvious to those skilled in the art that the following embodiments illustrate the present invention and various changes and modifications are possible within the scope of the present invention and the scope of the technical idea, and it is natural that such changes and modifications belong to the appended claims.

[0110] Hereinafter, preferred embodiments are shown to assist in understanding the present invention. However, the following embodiments are provided to more easily understand the present invention, and the present invention is not limited thereto.

[0111] In the following examples and comparative examples, a polymer solid electrolyte containing a polymer containing a crosslinkable functional group, a lithium salt, and a solvent was produced as shown in Table 1 below.

[0112]

Table 1

[0113] <Example> Example 1: Production of Polymer Solid Electrolyte PVA (Mw: 89,000 g / mol; degree of hydrolysis > 99%) was mixed with water to produce a 10% PVA aqueous solution. After adding LiTFSI to the PVA aqueous solution, it was stirred to produce a solution containing PVA, which is a polymer having a crosslinkable functional group, and LiTFSI, which is a lithium salt. At this time, the molar ratio ([Li] / [O]) of "O" contained in the crosslinkable functional group of the PVA and "Li" contained in the lithium salt was set to 0.1.

[0114] The solution was coated on an SS foil, which is a substrate, by the bar coating method to form a coating film. Then, it was frozen at -20°C for 24 hours and thawed at 25°C to produce the polymer solid electrolyte.

[0115] Example 2 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [O]) of "O" contained in the crosslinkable functional group of the PVA and "Li" contained in the lithium salt was 0.4.

[0116] Example 3 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [O]) of "O" contained in the crosslinkable functional group of the PVA and "Li" contained in the lithium salt was 0.4, and after removing water (H2O), which is the first solvent inside the produced polymer solid electrolyte, ethyl methyl carbonate (EMC), which is the second solvent, was added to produce the polymer solid electrolyte.

[0117] Example 4 A polymer solid electrolyte was produced in the same manner as in Example 3, except that the second solvent was DMC.

[0118] Example 5 A polymer solid electrolyte was produced in the same manner as in Example 3, except that the molar ratio ([Li] / [O]) of "O" contained in the crosslinkable functional group of the PVA and "Li" contained in the lithium salt was 0.25 and the first solvent was DMSO.

[0119] <Comparative Example> Comparative Example 1 A polymer solid electrolyte was produced in the same manner as in Example 3, except that a solution containing PVA, a polymer having a crosslinkable functional group, and LiTFSI, a lithium salt, was applied onto an SS foil (foil) as a substrate and then dried at 80 °C without a freezing and thawing process.

[0120] Comparative Example 2 A polymer solid electrolyte was produced in the same manner as in Example 3, except that a solution containing PVA, a polymer having a crosslinkable functional group, and LiTFSI, a lithium salt, was applied onto an SS foil (foil) as a substrate and then dried at 25 °C without a freezing and thawing process.

[0121] Comparative Example 3 A polymer solid electrolyte was produced in the same manner as in Example 2, except that PVA, a polymer having a crosslinkable functional group, was mixed with EMC, and a solution containing LiTFSI, a lithium salt, was applied onto an SS foil (foil) as a substrate and then dried at 80 °C without a freezing and thawing process.

[0122] Comparative Example 4 A polymer solid electrolyte was produced in the same manner as in Example 2, except that a PEO polymer was used instead of PVA and the PEO polymer was dissolved in acetonitrile.

[0123] Comparative Example 5 A polymer solid electrolyte was produced in the same manner as in Example 3, except that a PEO polymer was used instead of PVA.

[0124] Comparative Example 6 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [O]) of "O" contained in the crosslinkable functional group of the PVA and "Li" contained in the lithium salt was 0.5.

[0125] <Experimental Example> Experimental Example 1 To measure the ionic conductivity of the polymer solid electrolyte in film form produced in the examples and comparative examples, the polymer solid electrolyte was punched into a circle with a size of 1.7671 cm 2 and the punched polymer solid electrolyte was placed between two stainless steels (SS) to produce a coin cell.

[0126] Using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument), after measuring the resistance at 25 °C under the conditions of amplitude 10 mV and scan range 500 kHz to 20 MHz, the ionic conductivity of the polymer solid electrolyte was calculated using the following formula 1.

[0127] [Formula 1] [Number]

[0128] In the above formula 1, σ i is the ionic conductivity (S / cm) of the polymer solid electrolyte, R is the resistance (Ω) of the polymer solid electrolyte measured by the electrochemical impedance spectrometer, L is the thickness (μm) of the polymer solid electrolyte, and A is the area (cm 2 ) of the polymer solid electrolyte.

[0129] The results of observing the ionic conductivity of the polymer solid electrolyte calculated using the above formula 1, the possibility of forming a freestanding film, and the appearance of the polymer solid electrolyte are shown in Table 2 below. At this time, the possibility of forming the freestanding film (formed: O, not formed: X) and the appearance of the polymer solid electrolyte were observed with the naked eye.

[0130] [Table 2]

[0131] As shown in Table 2 above, by using PVA having a molar ratio of lithium of the crosslinkable functional group to lithium salt ([Li] / [OH]) within an appropriate range as the polymer containing the crosslinkable functional group and applying a freezing and thawing process, it was confirmed that a polymer solid electrolyte in the form of a free-standing film could be produced (Examples 1 to 5).

[0132] Comparative Example 1 is an electrolyte produced using a high-temperature drying process at 80°C and was in a liquid state rather than in a film form.

[0133] Comparative Example 2 is an electrolyte produced using a normal-temperature drying process at 25°C. Due to the absence of physical crosslinking formed by the freezing and thawing process, it was found that the mechanical strength of the polymer solid electrolyte was low and the ionic conductivity was also low.

[0134] Comparative Example 3 is an electrolyte produced using a high-temperature drying process at 80°C. PVA, which is a polymer containing a crosslinkable functional group, was put into an ethyl methyl carbonate (EMC) solvent to prepare a solution, but the PVA was not dissolved in the EMC solvent and was in a liquid state rather than in a film form.

[0135] In Comparative Examples 4 and 5, PEO was used as the polymer. However, it was found that no crosslinked structure was formed even when the freezing and thawing process was applied, and the ionic conductivity was extremely low.

[0136] Example 6 A polymer solid electrolyte was produced in the same manner as in Example 2, except that the freezing and thawing process was carried out for 2 cycles.

[0137] Example 7 A polymer solid electrolyte was produced in the same manner as in Example 2, except that the freezing and thawing process was carried out for 1 cycle.

[0138] Example 8 A polymer solid electrolyte was produced in the same manner as in Example 2, except that the freezing and thawing process was carried out for 5 cycles.

[0139] Example 9 A polymer solid electrolyte was produced in the same manner as in Example 2, except that the freezing and thawing processes were carried out for 10 cycles.

[0140] Comparative Example 7 PVA (Mw: 89,000 g / mol; degree of hydrolysis > 99%) was mixed with water to produce a 10 wt% PVA aqueous solution, which was then coated on an SS foil and dried at a high temperature (90 °C, 3 hours) to produce a PVA film.

[0141] Comparative Example 8 A PVA film was produced in the same manner as in Comparative Example 7, except that boric acid was added as a crosslinking agent.

[0142] Experimental Example 2 An experiment was conducted to compare the presence and degree of formation of the crosslinked bond structure inside the polymer solid electrolyte.

[0143] Since only the presence and degree of formation of the crosslinked bond structure were compared, the PVA film of Comparative Example 7 without a crosslinked bond structure and Comparative Example 8 in which a chemical crosslinked bond structure was formed by a crosslinking agent were used as comparison targets.

[0144] (1) Confirmation of the degree of swelling After immersing the experimental sample in water at room temperature (25 °C) for 12 hours, the degree of swelling of the sample was confirmed, and the degree of swelling was judged according to the following criteria.

[0145] <Judgment criteria for the degree of swelling> ◎: Swelling of 80% or more of the total volume. ○: Swelling of 50% or more of the total volume. △: Swelling of 20% or more of the total volume. X: Swelling of less than 10% of the total volume.

[0146] (2) Elastic modulus The elastic modulus was measured using a Universal testing machine (UTM).

[0147]

Table 3

[0148] Referring to Table 3 above, Examples 2 and 6 to 9 show an elastic modulus above a certain level as polymer solid electrolytes produced by the freezing and thawing processes. It can be seen that as the number of cycles of the freezing and thawing processes increases, the elastic modulus also increases accordingly. Also, as the number of cycles increases, the degree of swelling decreases. Generally, the degree of swelling and mechanical properties of polymers are greatly affected by the degree of crosslinking. The formation of crosslinking points plays a role in increasing the internal resistance of polymer chains, thereby inducing an increase in swelling resistance and mechanical strength. In particular, the formation of physical crosslinking bonds based on the freeze-thaw process is affected by the number of repetitions of the freeze-thaw process. From the results that the elastic modulus increases and the degree of swelling decreases as the number of cycles increases, it can be seen that the crosslinking structure also increases as the number of cycles increases. For example, even though Example 7 shows that the degree of swelling is 50% or more of the total volume, it is the result measured after 12 hours at room temperature, and it meets the physical properties required for polymer solid electrolytes for all-solid-state batteries.

[0149] It can be seen that more than 80% of the total volume of the PVA film of Comparative Example 7 is swollen, indicating that there is no crosslinking structure inside the polymer.

[0150] The PVA film of Comparative Example 8 has a chemically crosslinked structure formed by the addition of boric acid as a crosslinking agent, and it was shown that the elastic modulus decreased compared to Comparative Example 7 where no crosslinking structure was formed.

[0151] The PVA film of Comparative Example 8 has a chemically crosslinked structure formed, the crystallinity decreases, and the flexibility of the polymer increases, resulting in a decrease in the elastic modulus compared to Comparative Example 7.

[0152] On the other hand, Examples 2 and 6 to 9 correspond to PVA films in the form of hydrogels based on physical cross-linking formed using a freezing and thawing process, which is different from the manufacturing methods of Comparative Examples 7 and 8. As the cross-linking increases, the elastic modulus tends to increase. In Examples 2 and 6 to 9, as the number of freezing and thawing process cycles increased, the cross-linking structure also increased, and the elastic modulus also tended to increase. While undergoing the freezing and thawing process, some of the cross-linkable functional groups contained in PVA form localized crystallites, and the localized crystallites act as cross-linkable junction points, resulting in an increase in the elastic modulus.

[0153] As described above, even though the present invention is described by way of limited examples and drawings, the present invention is not limited thereby, and various modifications and variations are possible within the equivalent scope of the technical idea of the present invention and the scope of the claims described below by those having ordinary knowledge in the technical field to which the present invention pertains.

Claims

1. A polymer solid electrolyte comprising a polymer containing a crosslinkable functional group, a lithium salt, and a solvent containing a first solvent and a second solvent, wherein the polymer solid electrolyte includes a crosslinked structure and an amorphous polymer chain containing the crosslinkable functional group, and the crosslinked structure includes (a) a crosslink between crosslinkable functional groups, (b) a crosslink between a crosslinkable functional group and the first solvent, and (c) a bond between a crosslinkable functional group and a lithium salt.

2. The crosslink (a) between crosslinkable functional groups includes a hydrogen bond, the crosslink (b) between a crosslinkable functional group and the first solvent includes a hydrogen bond, and the bond (c) between a crosslinkable functional group and a lithium salt includes a bond due to a Lewis acid-base interaction. The polymer solid electrolyte according to claim 1.

3. The polymer solid electrolyte according to claim 1, wherein the content of the first solvent is 1 to 1000 ppm.

4. The first solvent includes one or more selected from the group consisting of water, ethanol, isopropyl alcohol, dimethyl sulfoxide, acetonitrile, NMP, a co-solvent obtained by mixing water and alcohol, and a co-solvent obtained by mixing water and dimethyl sulfoxide. The polymer solid electrolyte according to claim 1.

5. The second solvent contains one or more selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), dioxolane (DOX), dimethoxyethane (DME), diethoxyethane (DEE), γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane. The polymer solid electrolyte according to claim 1.

6. The crosslinkable functional group contains one or more selected from the group consisting of a hydroxyl group, a carboxyl group, and an amide group. The polymer solid electrolyte according to claim 1.

7. The polymer containing the crosslinkable functional group contains one or more selected from the group consisting of polyvinyl alcohol (PVA), gelatin, methylcellulose, agar, dextrin, poly(vinyl pyrrolidone), poly(acrylamide), starch-carboxymethyl cellulose, hyaluronic acid-methylcellulose, chitosan, poly(N-isopropylacrylamide), and amino-terminated polyethylene glycol (PEG). The polymer solid electrolyte according to claim 1.

8. The molar ratio ([Li] / [G]) of lithium ([Li]) of the lithium salt to the crosslinkable functional group ([G]) of the polymer is greater than 0.1 and less than 0.5, the polymer solid electrolyte according to claim 1.

9. The lithium salt is (CF ３ SO ２ ) ２ NLi (lithium bis(trifluoromethanesulfonyl)imide (Lithium bis(trifluoromethanesulphonyl)imide), LiTFSI), (FSO ２ ) ２ NLi (lithium bis(fluorosulfonyl)imide (Lithium bis(fluorosulphonyl)imide), LiFSI), LiNO ３ , LiOH, LiCl, LiBr, LiI, LiClO ４ , LiBF ４ , LiB １０ Cl １０ , LiPF ６ , LiCF ３ SO ３ , LiCF ３ CO ２ , LiAsF ６ , LiSbF ６ , LiAlCl ４ , CH ３ SO ３ Li, CF ３ SO ３ Li, LiSCN and LiC(CF ３ SO ２ ) ３ The polymer solid electrolyte according to claim 1, which contains one or more selected from the group consisting of.

10. The polymer solid electrolyte is in the form of a free-standing film or a coating layer, the polymer solid electrolyte according to claim 1.

11. The ionic conductivity of the polymer solid electrolyte is 1.0x10 －４ S / cm or more, the polymer solid electrolyte according to claim 1.

12. (S1) Adding a lithium salt to a solution containing a polymer having a crosslinkable functional group and a first solvent to produce a solution for forming a polymer solid electrolyte; (S2) Coating the solution for forming the polymer solid electrolyte on a substrate to form a coating film; (S3) Freezing and thawing the coating film to form a crosslinked structure of the polymer having the crosslinkable functional group, and the crosslinked structure of the polymer includes the first polymer solid electrolyte containing the lithium salt and the first solvent; (S4) Replacing the first solvent in the first polymer solid electrolyte with a second solvent to produce a second polymer solid electrolyte; A method for manufacturing a polymer solid electrolyte.

13. The polymer solid electrolyte includes a crosslinked structure, The crosslinked structure includes (a) a crosslink between crosslinkable functional groups, (b) a crosslink between a crosslinkable functional group and the first solvent, and (c) a bond between a crosslinkable functional group and a lithium salt. The crosslink (a) between crosslinkable functional groups includes a hydrogen bond. The crosslink (b) between a crosslinkable functional group and the first solvent includes a hydrogen bond. The bond (c) between a crosslinkable functional group and a lithium salt includes a bond by Lewis acid-base interaction. The method for manufacturing a polymer solid electrolyte according to Claim 12.

14. The freezing is performed at -30°C to -10°C. The method for manufacturing a polymer solid electrolyte according to Claim 12.

15. The thawing is performed at 15°C to 35°C. The method for manufacturing a polymer solid electrolyte according to Claim 12.

16. The solvent exchange is to dry the first solvent contained in the first polymer solid electrolyte at a high temperature and then immerse it in the second solvent to exchange the first solvent with the second solvent. The method for manufacturing a polymer solid electrolyte according to claim 12.

17. An all-solid-state battery comprising the polymer solid electrolyte according to any one of claims 1 to 11.

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