Polymer solid electrolyte and method for producing the same

Abstract

The present invention relates to a polymer solid electrolyte and a manufacturing method thereof. More specifically, the polymer solid electrolyte includes a cross-linked structure formed by a cross-linking functional group. The cross-linked structure includes (a) a cross-link between the cross-linking functional groups, (b) a cross-link between the cross-linking functional group and a solvent, and (c) a bond between the cross-linking functional group and a lithium salt. Therefore, the crystallinity of the polymer solid electrolyte can be reduced and the ionic conductivity can be improved without using a separate plasticizer.

Description

[Technical Field]

[0001] This application claims priority rights under Korean Patent Application No. 10-2022-0067041 dated May 31, 2022, and Korean Patent Application No. 10-2023-0070049 dated May 31, 2023, and incorporates all the contents disclosed in the documents of said Korean patent applications as part of this specification.

[0002] The present invention relates to polymer solid electrolytes and methods for producing the same. [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 due to deformation or external impact, a short circuit can occur, which can lead to dangers such as overheating and explosion. Therefore, the development of solid electrolytes that can ensure safety in the field of lithium-ion batteries is a very important issue.

[0004] Lithium-ion batteries using solid electrolytes offer several advantages, including improved battery safety, reduced electrolyte leakage, enhanced reliability, and easier manufacturing of thin batteries. Furthermore, the use of lithium metal as the negative electrode allows for increased energy density, making them promising for applications such as small secondary batteries and high-capacity secondary batteries for electric vehicles, and attracting attention as a next-generation battery.

[0005] Among solid electrolytes, polymer solid electrolytes may use ion-conducting polymer materials as raw materials, and hybrid materials in which polymer materials and inorganic materials are mixed have also been proposed. As the inorganic material, inorganic materials such as oxides or sulfides may be used.

[0006] Conventional polymer solid electrolytes were manufactured through a process of forming a coating film followed by high-temperature drying. However, conventional polymer solid electrolyte manufacturing techniques had limitations in producing polymer solid electrolytes with improved ionic conductivity due to the high crystallinity of crystalline or semi-crystalline polymers. In other words, the higher the degree of crystallinity of the polymer, the lower the chain 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] For example, conventional polymer solid electrolytes can be manufactured by using polyvinyl alcohol (PVA), which contains hydroxyl groups as crosslinking functional groups, as the polymer, forming a coating film, and then going through a high-temperature drying process. Specifically, the PVA can be dissolved in water to produce an aqueous PVA solution, which can then be applied to a substrate by solution casting to form a coating film, and dried at room temperature or high temperature to produce a PVA film-like polymer solid electrolyte. In this case, high temperature may mean 80°C or higher, which is the glass transition temperature (Tg) of PVA. In the drying process, after the water evaporates, hydrogen bonds are formed between the crosslinking functional groups contained in the PVA, and these hydrogen bonds cause chain folding of the polymer chains, resulting in a phenomenon in which the crystallinity of the polymer film increases. The higher the crystallinity, the more brittle the polymer film is formed. In polymer films with high crystallinity and brittleness, the chain mobility of the polymer chains decreases, and if dissociated ions are present inside the polymer film, the mobility of the ions also decreases significantly. Therefore, as mentioned above, general PVA films manufactured by a process of forming a coating film and then drying it at high temperature will exhibit physical properties that make them unsuitable as polymer solid electrolytes for lithium secondary batteries.

[0008] To overcome these limitations of conventional polymer solid electrolytes, techniques have been developed to improve the ionic conductivity of polymer solid electrolytes by adding plasticizers to crystalline or semi-crystalline polymers to improve the mobility of the polymer chains. However, when using plasticizers, it is necessary to ensure appropriate dispersion and miscibility between the polymer and the plasticizer, which can make it difficult to set the process conditions. Furthermore, when liquid plasticizers are applied, their compatibility with the polymer decreases, which can make it difficult to carry out the manufacturing process of polymer solid electrolytes.

[0009] Therefore, there is a need to develop technologies that can improve the ionic conductivity of polymer solid electrolytes without the need for additional additives such as plasticizers. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Chinese Published Patent No. 112259788 [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The 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 producing polymer solid electrolytes with improved ionic conductivity.

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

[0014] To achieve the above object, the present invention provides a polymer solid electrolyte comprising a polymer containing a crosslinkable functional group, a lithium salt, and a solvent, wherein the polymer solid electrolyte has a crosslinked structure; and contains 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 the crosslinkable functional group and the solvent, and (c) a bond between the crosslinkable functional group and the lithium salt.

[0015] The present invention also provides a method for producing the polymer solid electrolyte, comprising: (S1) adding a lithium salt to a polymer solution containing a crosslinkable functional group to form a solution for forming a polymer solid electrolyte; (S2) coating the solution for forming a polymer solid electrolyte on a substrate to form a coated film; and (S3) freezing and thawing the coated film.

[0016] The present invention also provides a 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 including a crosslinked structure formed by crosslinkable functional groups contained in the polymer and an amorphous polymer chain, 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.

Brief Description of the Drawings

[0019] [Figure 1] It is a graph showing the tendency of the ionic conductivity of the electrolyte according to the molar ratio ([Li] / [OH]) of the crosslinkable functional group and the lithium salt. [Figure 2] It is a photograph showing the electrolyte form according to the molar ratio ([Li] / [OH]) of the crosslinkable functional group and lithium.

Embodiments for Carrying Out the Invention

[0020] The present invention will be described in more detail below to aid in understanding it.

[0021] The terms and words used in this specification and in the claims shall not be construed to be limited to their ordinary or dictionary meanings, but rather shall be construed as meanings and concepts consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0022] As used herein, the term "crosslinked structure" refers to a structure that includes a three-dimensional frame formed by polymer chains and the internal space of the frame. The polymer chains may be formed by crosslinking bonds containing crosslinkable functional groups contained in the polymer. The crosslinked structure has a three-dimensional shape and a form in which polymer chains are intertwined with each other, and can therefore also be called a three-dimensional network structure.

[0023] Polymer solid electrolyte This invention relates to polymer solid electrolytes. The polymer solid electrolyte of the present invention is a polymer solid electrolyte comprising a polymer containing a crosslinkable functional group, a lithium salt, and a solvent, wherein the polymer solid electrolyte comprises a crosslinking structure and an amorphous polymer chain containing the crosslinkable functional group, and the crosslinking structure comprises (a) crosslinking between crosslinkable functional groups, (b) crosslinking between the crosslinkable functional group and the solvent, and (c) bonding between the crosslinkable functional group and the lithium salt. Specifically, the amorphous polymer chain and the lithium salt are contained in the internal space formed in the crosslinking structure, and the lithium salt is contained in a dissociated state.

[0024] Furthermore, the crosslinked structure may be formed by a freezing process as described later. In the freezing process, some of the crosslinkable functional groups contained in the polymer may form localized crystallites, and these localized crystallites may act as crosslinkable junction points to form the crosslinked structure. In this case, the term "crystallites" refers to a shape that resembles entangled threads forming knots, rather than a crystal structure formed by the folding of polymer chains.

[0025] In the present invention, the crosslinking between the crosslinkable functional groups (a) may include hydrogen bonds between the crosslinkable functional groups, for example, the hydrogen bonds may be hydrogen bonds between OH- groups.

[0026] If the crosslinking structure consists only of crosslinking between the (a) crosslinkable functional groups, the polymer solid electrolyte may develop crystallinity, potentially leading to a decrease in ionic conductivity.

[0027] However, since the crosslinking structure includes not only (a) crosslinking between crosslinking functional groups, but also (b) crosslinking between crosslinking functional groups and the solvent, and (c) bonding between crosslinking functional groups and the lithium salt, it is possible to prevent the formation of crystallinity in the polymer solid electrolyte.

[0028] In the present invention, the crosslinking between the (b) crosslinkable functional group and the solvent may include hydrogen bonds, for example, the hydrogen bond may be a hydrogen bond between OH- and H+. In this case, H+ may originate from the aqueous solvent.

[0029] The crosslinking between the crosslinkable functional group and the solvent in (b) above may also refer to hydrogen bonding between the crosslinkable functional group and some of the solvent remaining after the freezing and thawing process.

[0030] Furthermore, the crosslinking between the (b) crosslinkable functional group and the solvent prevents crosslinking between the (a) crosslinkable functional groups, and prevents the crosslinked structure from consisting solely of crosslinking between the (a) crosslinkable functional groups, thereby preventing an increase in the crystallinity of the polymer solid electrolyte.

[0031] In the present invention, the bond between the (c) crosslinkable functional group and the lithium salt may include a bond formed by a Lewis acid-base interaction, for example, the bond may be between OH- and Li+.

[0032] The bonding of the (c) crosslinkable functional group to the lithium salt prevents the crosslinking between the (a) crosslinkable functional groups and the (b) crosslinkable functional group to the solvent, so that the crosslinked structure is not composed solely of crosslinking between the (a) crosslinkable functional groups. This prevents the formation of crystallinity in the polymer solid electrolyte while simultaneously promoting the formation of amorphous polymer chains. As amorphous polymer chains are formed, the mobility of the polymer chains improves, increasing the hopping effect of lithium ions and improving the ionic conductivity of the polymer solid electrolyte.

[0033] In the present invention, the amorphous polymer chain can also be formed by a freezing process as described later, and refers to a polymer chain that does not form crystals by regular folding of the polymer chain and exists in a state of free behavior. That is, the amorphous polymer chain may include a polymer containing a crosslinking functional group that does not form bonds such as those described in (a), (b), and (c).

[0034] Due to the aforementioned cross-linking structure, the polymer solid electrolyte is not easily interrupted or destroyed, and thus can function as an electrolyte support that stably contains lithium ions.

[0035] Furthermore, the amorphous polymer chains allow the polymer solid electrolyte to exhibit elasticity, minimizing its brittleness and resulting in excellent polymer chain mobility. This improves the mobility of lithium ions within the electrolyte, thus providing a polymer solid electrolyte with improved ionic conductivity.

[0036] In the present invention, the crosslinking functional group contained in the polymer containing the crosslinking functional group can have the property of forming a crosslinked structure by forming bonds as shown in (a), (b), and (c) above.

[0037] For example, the crosslinking functional group may include one or more selected from the group consisting of a hydroxyl group, a carboxyl group, and an amide group.

[0038] Furthermore, the weight-average molecular weight (Mw) of the polymer containing the crosslinking functional group may be between 80,000 g / mol and 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 be 90,000 g / mol or less, 110,000 g / mol or less, or 130,000 g / mol or less. If the weight-average molecular weight (Mw) of the polymer containing the crosslinking functional group is less than 80,000 g / mol, the bonds formed by the crosslinking functional group may not be sufficiently formed to obtain a crosslinked structure. If the weight-average molecular weight (Mw) of the polymer containing the crosslinking 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 interior of the polymer chains decreases. This can accelerate the gelation of the polymer, reducing its solubility and potentially hindering the smooth formation of crosslinked structures by crosslinking functional groups.

[0039] Furthermore, the polymer containing the crosslinking functional group may have the characteristic that the phase separation between the polymer and the solvent occurs smoothly in the polymer solution used in the manufacturing process, and that the bonds of (a), (b), and (c) are successfully formed by the crosslinking functional group contained in the phase-separated polymer during freezing.

[0040] For example, the polymer containing the crosslinking functional group may include one or more selected from the group consisting of polyvinyl alcohol (PVA), gelatin, methylcellulose, agar, dextrin, poly(vinyl pyrrolidone), poly(ethylene oxide), poly(acrylamide), poly(acrylic acid, PAA), starch-carboxymethylcellulose, hyaluronic acid-methylcellulose, chitosan, poly(N-isopropylacrylamide), and amino-terminated polyethylene glycol (PEG). Preferably, the polymer containing the crosslinking functional group may be PVA, which may be advantageous in the manufacturing process of polymer solid electrolytes because, during freezing, the phase separation between the PVA and the solvent is efficiently performed, and the crosslinking structure is formed by the bonds of (a), (b), and (c) derived from the crosslinking functional group of the PVA that has phase-separated from the solvent.

[0041] In the present invention, the lithium salt is contained in a dissociated state within the internal space of the crosslinked bonding structure, and the ionic conductivity of the polymer solid electrolyte can be improved.

[0042] Furthermore, the lithium salt can (c) form a bond between the crosslinking functional group and the lithium salt, thereby preventing the formation of crystallinity in the polymer solid electrolyte while simultaneously promoting the formation of amorphous polymer chains.

[0043] The lithium salts mentioned above are (CF3SO2)2NLi (Lithium bis(trifluoromethanesulfonicyl) imide, LiTFSI), (FSO2)2NLi (Lithium bis(fluorosulfonyl) imide, LiFSI), LiNO3, LiOH, LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 It may also contain one or more selected from the group consisting of LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, and LiC(CF3SO2)3.

[0044] In the present invention, the molar ratio ([Li] / [G]) of the crosslinking functional group ([G]) of the polymer containing the crosslinking functional group in the polymer solid electrolyte to the lithium ([Li]) of the lithium salt may be greater than 0.1 and less than 0.5, specifically greater than 0.1, 0.2 or more, or 0.3 or more, and 0.4 or less or less than 0.5. If the molar ratio ([Li] / [G]) is 0.1 or less, the content of the lithium salt may decrease, potentially lowering the ionic conductivity of the polymer solid electrolyte. If it is 0.5 or more, the content of the polymer containing the crosslinking functional group may decrease, preventing sufficient formation of the bonds described in (a), (b), and (c), which may increase crystallinity and lower the ionic conductivity. If the crosslinking functional group is a hydroxyl group (OH-), then [G] can be written as [OH] or [O].

[0045] 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-like state on its own at room temperature and pressure without the need for a separate support. The coating layer means a layer obtained by coating a substrate. When the polymer solid electrolyte is in the form of a coating layer, the coating layer may be a layer coated on an electrode.

[0046] The freestanding film or coating layer exhibits elasticity, minimizes brittleness, and possesses the properties of a support that stably contains lithium ions, making it a suitable form for a polymer solid electrolyte.

[0047] In the present invention, the ionic conductivity of the polymer solid electrolyte is 10 -4 It may be S / cm or higher.

[0048] The aforementioned polymer solid electrolyte exhibits low crystallinity and improved ionic conductivity due to its structural properties, including the aforementioned cross-linking structure. As a result, despite being a solid electrolyte, it exhibits ionic conductivity at a level equivalent to or higher than conventional liquid electrolytes, thereby improving the performance of all-solid-state batteries.

[0049] In the present invention, the polymer solid electrolyte may further contain a liquid electrolyte, and the liquid electrolyte can further improve the ionic conductivity of the polymer solid electrolyte. The liquid electrolyte may also be contained within the internal space of the crosslinking structure.

[0050] The liquid electrolyte may be any liquid electrolyte commonly used in the industry, and its composition is not particularly limited as long as it can be used in a lithium secondary battery. For example, the liquid electrolyte may include a lithium salt and a non-aqueous solvent. The lithium salt may be any one of the lithium salts described above. The non-aqueous solvent may also include one or more selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate (VC), diethyl carbonate (DEC), dimethyl carbonate (DMC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX), dimethoxyethane (DME), diethoxyethane (DEE), γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane.

[0051] Furthermore, the liquid electrolyte may be present in an amount of 1 to 5% by weight based on the total weight of the polymer solid electrolyte. If the content of the liquid electrolyte is 1% by weight or less, the effect of improving ionic conductivity may be minimal, and if it exceeds 5% by weight, stability may decrease.

[0052] The polymer solid electrolyte described above can be manufactured in a form that includes a polymer chain containing a polymer with crosslinking structures formed by bonds such as (a), (b), and (c) above, which are formed by crosslinking functional groups contained in the polymer, and a polymer having crosslinking functional groups that do not form crosslinks. Due to these morphological characteristics, the polymer solid electrolyte can act as a support that stably contains lithium ions, exhibits elasticity and minimizes brittleness, prevents the formation of crystallinity and improves ionic conductivity.

[0053] Method for producing polymer solid electrolytes The present invention also relates to a method for producing a polymer solid electrolyte, comprising: (S1) adding a lithium salt to a polymer solution containing a crosslinking functional group to form a polymer solid electrolyte forming solution; (S2) applying the polymer solid electrolyte forming solution onto a substrate to form a coating film; and (S3) freezing and thawing the coating film.

[0054] In the method for producing the polymer solid electrolyte laminate, crystallization of the polymer can be prevented by inducing (a) crosslinking between crosslinking functional groups, (b) crosslinking between crosslinking functional groups and the solvent, and (c) bonding between crosslinking functional groups and the lithium salt through a freezing process, without adding a plasticizer which was previously used to reduce the crystallinity of the polymer. As a result, a polymer solid electrolyte with improved ionic conductivity can be produced.

[0055] The method for producing the polymer solid electrolyte according to the present invention will be described in more detail below, step by step.

[0056] In the present invention, in step (S1), a lithium salt can be added to a polymer solution containing a crosslinking functional group to form a polymer solid electrolyte solution. The types and properties of the polymer containing the crosslinking functional group and the lithium salt are as described above.

[0057] The solvent used in the production of the polymer solution may be a polar solvent, such as water. In other words, the polymer solution may be an aqueous polymer solution.

[0058] The concentration of the polymer solution containing the crosslinking functional group can be appropriately adjusted to ensure that the coating process proceeds smoothly when applying the polymer solid electrolyte forming solution to the substrate. For example, the concentration of the polymer solution containing the crosslinking functional group may be 5% to 20%, specifically 5% or more, 7% or more, or 9% or more, or 13% or less, 17% or less, or 20% or less. If the concentration of the polymer solution containing the crosslinking functional group is less than 5%, the concentration is excessively dilute and may run off when applied to the substrate. If it exceeds 20%, it may be difficult to dissolve the lithium salt at the desired concentration in the polymer solution, and the high viscosity may make it difficult to coat it in a uniform thin film.

[0059] In the present invention, in step (S2), the polymer solid electrolyte forming solution can be applied to a substrate to form a coating film.

[0060] The substrate is not particularly limited as long as it can serve as a support to which the polymer solid electrolyte forming solution is applied. For example, the substrate may be stainless steel (SS), 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.

[0061] Furthermore, the coating method is not particularly limited as long as it is a method that can coat the polymer solid electrolyte forming solution onto the substrate in a film-like manner. 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.

[0062] In the present invention, in step (S3), the coated film can be frozen and thawed to form a crosslinked structure. That is, in the freezing step, the crosslinkable functional groups induce the bonding of (a), (b), and (c), forming a crosslinked structure and creating an amorphous polymer chain.

[0063] In the freezing process, the polymer and water in the aqueous polymer solution containing the crosslinking functional groups used to form the coating film can undergo phase separation. This phase separation may be induced because the hydrogen bonds between water molecules are stronger than the hydrogen bonds between the crosslinking functional groups and water molecules. The water molecules aggregated by the hydrogen bonds between water molecules exist in an ice state (ice phase) during the freezing process. As a result, the number of crosslinking functional groups that form hydrogen bonds through interaction with water molecules is significantly reduced.

[0064] In other words, in the freezing process of the coated film, the polymer and water contained in the polymer aqueous solution must first undergo phase separation, and this phase separation can be induced by hydrogen bonding between water molecules.

[0065] As a result of the phase separation, the interior of the coated film is divided into (i) a polymer-poor phase and (ii) a polymer-rich phase.

[0066] The aforementioned (i) polymer poor phase is a portion containing water molecules aggregated by hydrogen bonds between water molecules, existing in an ice state (ice phase), which can also be described as a free water state.

[0067] The polymer-rich phase (ii) is a portion containing a polymer that has undergone phase separation from water. This phase-separated polymer contains crosslinking functional groups that are free from interaction with water molecules. After phase separation, it becomes free and does not form crystals through regular folding, existing in a relatively free, amorphous state, which is called an amorphous polymer chain.

[0068] Furthermore, some of the crosslinking functional groups contained in the phase-separated polymer form localized crystallites. These localized crystallites act as crosslinkable junction points, forming a crosslinked structure that includes the bonds of (a), (b), and (c).

[0069] Furthermore, in the thawing step after the freezing step, the ice contained in the (i) polymer poor phase melts and evaporates, and a polymer solid electrolyte with increased free volume can be produced.

[0070] Furthermore, the freezing may be carried out under conditions that are appropriate for freezing the coating film. For example, the freezing temperature may be between -30°C and -10°C. Specifically, the freezing temperature may be -30°C or higher, -25°C or higher, or -23°C or higher, or -18°C or lower, -15°C or lower, or -10°C or lower. If the freezing temperature is below -30°C, cracks may occur in the coating film, and if it is above -10°C, phase separation between the polymer and water may not occur sufficiently, making it difficult to form amorphous polymer chain regions. In addition, the freezing may be carried out within a range of 20 to 30 hours, taking into consideration the time required for sufficient freezing.

[0071] Furthermore, the thawing process may be carried out under conditions that appropriately select conditions that allow the frozen coating film to thaw to a degree that it can be used as a polymer solid electrolyte. For example, the thawing temperature may be 15°C to 35°C, or it may be room temperature (25°C). If the thawing temperature is below 15°C, the moisture drying efficiency after thawing (ice melting) may decrease, and if it exceeds 35°C, the coating film may shrink, causing wrinkles or warping.

[0072] As described above, the freezing and thawing process induces the bonding of (a), (b), and (c), forming a cross-linked structure and creating an amorphous polymer chain.

[0073] Therefore, the degree of cross-linking structure formation can be adjusted by the number of times the freezing and thawing process is performed. When the process of performing the freezing process followed by the thawing process is considered one cycle, the freezing and thawing process may be performed for one or more cycles, two or more cycles, three or more cycles, or five or more cycles. The upper limit of the cycle is not particularly limited, but it may be 10 cycles or less, 13 cycles or less, or 15 cycles or less. Within this range, the more cycles of the freezing and thawing process are performed, the more cross-linking structures are formed, thereby increasing the modulus and strength of the polymer solid electrolyte.

[0074] After the step (S3), the method may further include a step (S4) of supporting the polymer solid electrolyte on a liquid electrolyte and then drying it, and the composition and content of the liquid electrolyte are as described above.

[0075] 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 includes a negative electrode, a positive electrode, and a polymer solid electrolyte interposed between the negative electrode and the positive electrode, and the solid electrolyte has the above-described characteristics.

[0076] 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, making it suitable as an electrolyte for an all-solid-state battery.

[0077] 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.

[0078] The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material.

[0079] 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 elements thereof; 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 comprises Mn and one or more elements selected from the group consisting of Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M' is one or more elements selected from the group consisting of Al, Mg, and B; and A is one or more elements selected from the group consisting of P, F, S, and N.) A layered compound such as, or a compound 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 to 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 is 0.01 to 0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented as O2 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., are examples, but are not limited to these.

[0080] 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 wet positive electrode active material layer and the dry positive electrode active material layer may become insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0081] Furthermore, the binder contains components that assist in the bonding of the positive electrode active material to conductive materials and to the current collector, such as 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, and polyvinyl acetate. The binder may contain one or more selected from the group consisting of polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl scrophularis, 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 contain one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0082] 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 content of the positive electrode active material will decrease accordingly, potentially reducing the battery capacity.

[0083] 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, does not induce chemical changes in the battery, and has excellent electrical conductivity. Typically, graphite or conductive carbon may 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, lamp black, and summer 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. These may be used individually or in combination of two or more, but are not necessarily limited to these.

[0084] The conductive material may be included 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 too 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 too high, exceeding 30% by weight, the amount of positive electrode active material will be relatively small, and the capacity and energy density may decrease. The method of incorporating the conductive material into the positive electrode is not particularly limited, and conventional methods known in the art, such as coating the positive electrode active material, may be used.

[0085] 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.

[0086] The positive electrode 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, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or aluminum-cadmium alloy may be used as the positive electrode current collector.

[0087] The positive electrode current collector may have a fine uneven surface or employ a three-dimensional porous structure to strengthen the bonding force with the positive electrode active material layer. As a result, the positive electrode current collector may include various forms such as film, sheet, foil, mesh, net, porous material, foam, and nonwoven fabric.

[0088] The positive electrode described above can be manufactured by conventional methods. Specifically, it can be manufactured by mixing a positive electrode active material, a conductive material, and a binder in an organic solvent to produce a composition for forming a positive electrode active material layer, which is then coated onto a positive electrode current collector and dried, and then selectively compress-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 evaporates easily. Examples include acetonitrile, methanol, ethanol, tetrahydrofuran, water, and isopropyl alcohol.

[0089] In the present invention, the negative electrode included in the all-solid-state battery includes 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.

[0090] The negative electrode active material is lithium (Li + The material may include a substance that can be reversibly intercalated or deintercalated, a substance that can react with lithium ions to reversibly form a lithium-containing compound, or a lithium metal or lithium alloy.

[0091] The aforementioned lithium ion (Li +The material that can reversibly insert or remove the lithium ion (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + A substance that can reversibly form 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) and 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).

[0092] Preferably, the negative electrode active material may be lithium metal, and specifically, it may be in the form of a lithium metal thin film or lithium metal powder.

[0093] 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% by weight or more, or 50% by weight or more, or 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.

[0094] Furthermore, the binder is as described above for the positive electrode active material layer.

[0095] Furthermore, the conductive material is as described above for the positive electrode active material layer.

[0096] Furthermore, the negative electrode current collector is not particularly limited as long as it does not induce a chemical change in the battery and is conductive. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., or aluminum-cadmium alloy. Also, similar to the positive electrode current collector, the negative electrode current collector may be made of various forms such as films, sheets, foils, nets, porous materials, foams, or nonwoven fabrics with fine irregularities formed on their surface.

[0097] The method for manufacturing the negative electrode is not particularly limited, and the negative electrode active material layer may be formed on the negative electrode current collector using a layer or film formation method commonly used in the industry. For example, methods such as crimping, coating, and 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.

[0098] Furthermore, the present invention provides 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.

[0099] 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.

[0100] The following examples illustrate the present invention, but it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the invention and the technical concept, and that such changes and modifications will naturally fall within the scope of the claims.

[0101] In the following examples and comparative examples, polymer solid electrolytes were produced by varying the presence or absence of encapsulation of crosslinking functional groups, the type of polymer containing crosslinking functional groups, the molar ratio of the crosslinking functional groups to lithium ions, and whether or not a freeze / thaw process was applied, as shown in Table 1 below.

[0102] [Table 1]

[0103] Example 1 A 10% aqueous solution of PVA (Mw: 89,000 g / mol; degree of hydrolysis: >99%) was mixed with water. LiTFSI was added to the aqueous PVA solution and stirred to prepare a solution containing PVA, a polymer having crosslinking functional groups, and LiTFSI, a lithium salt. At this time, the molar ratio ([Li] / [OH]) of the crosslinking functional group "OH" of PVA to the "Li" of the lithium salt was set to 0.4.

[0104] The aforementioned solution was applied to a substrate, SS foil, by a bar coating method to form a coating film. The film was then frozen at -20°C for 24 hours and thawed at 25°C to produce a polymer solid electrolyte.

[0105] Example 2 A polymer solid electrolyte was prepared in the same manner as in Example 1, except that PVA with a weight-average molecular weight (Mw) of 85,000 g / mol was used.

[0106] Example 3 A polymer solid electrolyte was prepared in the same manner as in Example 1, except that PVA with a weight-average molecular weight (Mw) of 100,000 g / mol was used.

[0107] Example 4 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [OH]) of the crosslinking functional group "OH" of PVA to "Li" of the lithium salt was set to 0.1.

[0108] Example 5 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [OH]) of "O" contained in the crosslinking functional group of PVA and "Li" in the lithium salt was set to 0.2.

[0109] 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 crosslinking functional group of PVA and "Li" contained in the lithium salt was set to 0.3.

[0110] Comparative Example 1 A polymer solid electrolyte was produced in the same manner as in Example 1, except that a solution containing PVA, a polymer having crosslinking functional groups, and LiTFSI, a lithium salt, was applied to a substrate (SS foil) and then dried at 80°C.

[0111] Comparative Example 2 A polymer solid electrolyte was produced in the same manner as in Example 1, except that PEO, a polymer that does not have crosslinking functional groups, was used instead of PVA.

[0112] Comparative Example 3 A polymer solid electrolyte was produced in the same manner as in Comparative Example 1, except that a solution containing PVA, a polymer having crosslinking functional groups, and LiTFSI, a lithium salt, was applied to a substrate (SS foil) and then dried at room temperature (25°C).

[0113] Comparative Example 4 A polymer solid electrolyte was prepared in the same manner as in Example 1, except that a 35% aqueous solution of poly(acrylic acid, PAA) (Mw: 100,000 g / mol) was used instead of PVA.

[0114] Comparative Example 5 A polymer solid electrolyte was prepared in the same manner as in Example 1, except that PVA with a weight-average molecular weight (Mw) of 50,000 g / mol was used.

[0115] Comparative Example 6 A polymer solid electrolyte was prepared in the same manner as in Example 1, except that PVA with a weight-average molecular weight (Mw) of 146,000 g / mol was used.

[0116] Comparative Example 7 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [OH]) of "O" contained in the crosslinking functional group of PVA and "Li" in the lithium salt was set to 0.5.

[0117] Comparative Example 8 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the molar ratio ([Li] / [OH]) of "O" contained in the crosslinking functional group of PVA and "Li" in the lithium salt was set to 0.52.

[0118] Experimental Example 1 To measure the ionic conductivity of the film-like polymer solid electrolytes produced in the examples and comparative examples, 1.7671 cm² was used. 2The polymer solid electrolyte was punched out into a circular shape, and the punched-out polymer solid electrolyte was placed between two pieces of stainless steel (SS) to manufacture a coin cell.

[0119] Using an electrochemical impedance spectrometer (EIS, VM3, Bio Logic Science Instrument), the resistance was measured at 25°C with an amplitude of 10 mV and a scan range of 500 kHz to 20 MHz. The ionic conductivity of the polymer solid electrolyte was then calculated using the following formula 1.

[0120]

number

[0121] In the above formula 1, σ i R 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 (cm²) of the polymer solid electrolyte. 2 ) means.

[0122] The ionic conductivity of the polymer solid electrolyte calculated using Equation 1, the possibility of forming a freestanding film, and the results of observing the appearance of the polymer solid electrolyte are shown in Table 2 below. At this time, the possibility of forming a freestanding film (formed: ○, not formed: ×) and the appearance of the polymer solid electrolyte were observed with the naked eye.

[0123] [Table 2A] [Table 2B]

[0124] As shown in Table 2 above, it was confirmed that a freestanding film-like polymer solid electrolyte can be produced by applying a freezing and thawing process to PVA having an appropriate molecular weight range and a molar ratio ([Li] / [OH]) of the crosslinking functional group to the lithium salt (Examples 1, 2, 3, 5, and 6).

[0125] Comparative Example 4 used PAA as the polymer containing crosslinking functional groups. However, after the formation of the coated film, it froze during the freezing process and became liquid again during the thawing process, making it impossible to produce a freestanding film-like polymer solid electrolyte.

[0126] Furthermore, in Comparative Example 5, the molecular weight of the PVA was low, and it was manufactured in liquid form, so a free-standing film-like polymer solid electrolyte could not be obtained.

[0127] Furthermore, in Comparative Example 6, the molecular weight of the PVA was high, making it impossible to obtain a solution for forming a coating film, and thus the electrolyte manufacturing process could not be carried out.

[0128] Furthermore, in Example 4, a polymer solid electrolyte in the form of a free-standing film was produced when observed with the naked eye, but its ionic conductivity was remarkably low, and brittleness was also observed. This is because the molar ratio of cross-linking functional groups to lithium ([Li] / [OH]) was small, and although a cross-linking structure was formed, it was not formed sufficiently to be suitable for application as a polymer solid electrolyte.

[0129] Furthermore, in Comparative Example 7, the molar ratio ([Li] / [OH]) of the crosslinking functional group to lithium was large, resulting in the production of a highly viscous gel rather than a film. Although the gel had high ionic conductivity, it was confirmed that it was unsuitable for application as a polymer solid electrolyte because it was in gel form rather than film form. A gel state refers to a solid state with low mechanical strength that prevents it from being peeled from the substrate, or a highly viscous liquid state, making it difficult to apply as a polymer solid electrolyte.

[0130] Furthermore, in Comparative Example 8, the molar ratio ([Li] / [OH]) of the crosslinking functional group to lithium was greater than in Example 1, and a highly viscous gel was produced instead of a film. Although the gel had high ionic conductivity, it was confirmed that it was unsuitable for application as a polymer solid electrolyte because it was in gel form rather than film form.

[0131] Comparative Example 1 is an electrolyte manufactured using a high-temperature drying process at 80°C, resulting in a highly viscous gel-like electrolyte. A uniform coating film could not be formed on the substrate, and during film formation, phenomena such as bubbles, aggregation, and warping occurred.

[0132] Comparative Example 2 was an electrolyte produced using PEO that did not have crosslinking functional groups, and was in liquid form rather than film form.

[0133] Comparative Example 3 is a polymer solid electrolyte manufactured using a room-temperature drying process. It was found that the absence of physical crosslinking bonds formed by the freezing and thawing process resulted in low mechanical strength and low ionic conductivity of the polymer solid electrolyte.

[0134] Figure 1 is a graph showing the trend of ionic conductivity of electrolytes based on the molar ratio ([Li] / [OH]) of the crosslinking functional group and the lithium salt.

[0135] Referring to Figure 1, the molar ratio of lithium to crosslinking functional groups ([Li] / [OH], n) in the electrolyte produced in the freezing and thawing process. Li / n PVA It can be seen that the ionic conductivity of the polymer solid electrolyte tends to increase as the ) increases. Comparative Example 3 was manufactured using a room-temperature drying process, and it can be seen that its ionic conductivity is remarkably low.

[0136] Figure 2 is a photograph showing the electrolyte morphology based on the molar ratio ([Li] / [OH]) of the cross-linking functional group and lithium.

[0137] Referring to Figure 2, it can be seen that Example 4, in which the molar ratio ([Li] / [OH]) of crosslinking functional groups to lithium was 0.1, was a brittle film; Comparative Example 7, in which the molar ratio was 0.5, was a highly viscous gel; and Examples 1, 5, and 6, in which the molar ratio was between 0.1 and 0.5, produced film-like polymer solid electrolytes.

[0138] Example 7 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the freezing and thawing process was performed in two cycles.

[0139] Example 8 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the freezing and thawing process was performed in three cycles.

[0140] Example 9 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the freezing and thawing process was performed five times.

[0141] Example 10 A polymer solid electrolyte was produced in the same manner as in Example 1, except that the freezing and thawing process was performed 10 times.

[0142] Comparative Example 9 PVA (Mw: 89,000 g / mol; degree of hydrolysis: >99%) was mixed with water to prepare a 10% PVA aqueous solution. This solution was then coated onto SS foil and dried at high temperature (90°C, 3 hours) to produce a PVA film.

[0143] Comparative Example 10 A PVA film was manufactured in the same manner as in Comparative Example 9, except that boric acid was added as a crosslinking agent.

[0144] Experimental Example 2 We conducted experiments to compare the presence and degree of cross-linking structure formation within polymer solid electrolytes.

[0145] Since the comparison is based solely on the presence and degree of cross-linking structure formation, Comparative Example 8, a PVA film that does not contain a cross-linking structure, and Comparative Example 9, in which a chemically cross-linked structure was formed by a cross-linking agent, were used as comparison subjects.

[0146] (1) Confirmation of the degree of swelling After immersing the experimental samples in water at room temperature (25°C) for 12 hours, the degree of swelling of the samples was checked and judged according to the following criteria.

[0147] <Criteria for determining the degree of swelling> ◎: More than 80% of the total volume has swollen. ○: Swelling by more than 50% of the total volume. △: Swelled by more than 20% of the total volume. ×: The swelling is less than 10% of the total volume.

[0148] (2) Modulus The modulus was measured using a Universal Testing Machine (UTM).

[0149] [Table 3]

[0150] Referring to Table 3, Examples 1 and 7-10 are polymer solid electrolytes produced by a freeze-thaw process, exhibiting a modulus above a certain level, and showing an increase in modulus as the number of freeze-thaw cycles increases. Furthermore, the degree of swelling also decreased as the number of cycles increased. Generally, the degree of swelling and mechanical properties of polymers are greatly influenced by the degree of crosslinking. The formation of crosslinking points plays a role in increasing the internal resistance of the polymer chain, 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 influenced by the number of freeze-thaw cycles. From the results showing that the modulus increases and the degree of swelling decreases as the number of cycles increases, it can be seen that the number of crosslinking structures also increases as the number of cycles increases. Although Example 1 showed a degree of swelling of 50% or more of the total volume, this was measured after 12 hours at room temperature, and is suitable for the physical properties required for polymer solid electrolytes for all-solid-state batteries.

[0151] In Comparative Example 9, it was found that more than 80% of the PVA film swelled, indicating that the polymer did not contain any cross-linking structures.

[0152] The PVA film of Comparative Example 10 had a chemically cross-linked structure formed by the addition of boric acid, a cross-linking agent, and it can be seen that the modulus was reduced compared to Comparative Example 9, in which no cross-linked structure was formed.

[0153] The PVA film of Comparative Example 10 has a chemically cross-linked structure, resulting in reduced crystallinity and increased polymer flexibility, which leads to a decrease in modulus compared to Comparative Example 9.

[0154] On the other hand, Examples 1 and 7-10, unlike the manufacturing methods of Comparative Examples 9 and 10, correspond to hydrogel-like PVA films based on physical crosslinking formed using a freeze-thaw process. This shows a tendency for the modulus to increase as the number of crosslinks increases. In Examples 1 and 7-10, the number of crosslinking structures and the modulus tended to increase as the number of freeze-thaw cycles increased. During the freeze-thaw process, some of the crosslinking functional groups contained in the PVA form localized crystallites, and these localized crystallites act as cross-linkable junction points, increasing the modulus.

[0155] Although the present invention has been described above with limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations can be made by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the technical concept of the present invention and the claims described below.

Claims

1. A polymer solid electrolyte comprising a polymer containing a crosslinking functional group, a lithium salt, and a solvent, The polymer solid electrolyte comprises a crosslinking structure and an amorphous polymer chain containing the crosslinking functional group. The aforementioned crosslinking structure includes (a) crosslinking between crosslinking functional groups, (b) crosslinking between a crosslinking functional group and the solvent, and (c) bonding between a crosslinking functional group and a lithium salt. The polymer containing the aforementioned crosslinking functional group is polyvinyl alcohol (PVA). A polymer solid electrolyte in which the molar ratio ([Li] / [G]) of the crosslinking functional group ([G]) of the polymer to the lithium ([Li]) of the lithium salt is greater than 0.1 and less than 0.

5.

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

3. The polymer solid electrolyte according to claim 1, wherein the weight-average molecular weight (Mw) of the polymer containing the crosslinking functional group is 80,000 g / mol to 130,000 g / mol.

4. The lithium salt is (CF ３ SO ２ ), ２ NLi (Lithium bis(trifluoromethanesulphonyl)imide, LiTFSI), (FSO ２ ), ２ NLi (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

5. The polymer solid electrolyte according to claim 1, wherein the solvent contains water.

6. The polymer solid electrolyte according to claim 1, wherein the polymer solid electrolyte is in the form of a freestanding film or a coating layer.

7. The ionic conductivity of the polymer solid electrolyte is 10 －４ The polymer solid electrolyte according to claim 1, wherein the S / cm is 1 or higher.

8. The polymer solid electrolyte according to claim 1, wherein the polymer solid electrolyte further comprises a liquid electrolyte.

9. (S1) A step of adding a lithium salt to a polymer solution containing crosslinking functional groups to form a polymer solid electrolyte solution; (S2) A step of applying the polymer solid electrolyte forming solution onto a substrate to form a coating film; and A method for producing a polymer solid electrolyte, comprising the steps of (S3) freezing and thawing the coated film, The polymer containing the aforementioned crosslinking functional group is polyvinyl alcohol (PVA). A method for producing a polymer solid electrolyte, wherein the molar ratio ([Li] / [G]) of the crosslinking functional group ([G]) of the polymer to the lithium ([Li]) of the lithium salt is greater than 0.1 and less than 0.

5.

10. The polymer solid electrolyte includes a crosslinking structure, The aforementioned crosslinking structure includes (a) crosslinking between crosslinking functional groups, (b) crosslinking between a crosslinking functional group and a solvent, and (c) bonding between a crosslinking functional group and a lithium salt. The crosslinking between the crosslinkable functional groups includes hydrogen bonding, The crosslinking bond between the (b) crosslinkable functional group and the solvent includes a hydrogen bond. The method for producing a polymer solid electrolyte according to claim 9, wherein the bonding between the crosslinkable functional group and the lithium salt includes bonding by Lewis acid-base interaction.

11. The method for producing a polymer solid electrolyte according to claim 9, wherein the freezing is performed at a temperature of -30°C to -10°C.

12. The method for producing a polymer solid electrolyte according to any one of claims 9 to 11, wherein the thawing is performed at a temperature of 15°C to 35°C.

13. An all-solid-state battery comprising a polymer solid electrolyte according to any one of claims 1 to 8.

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