Polymer Electrolyte Composition for All-Solid-State Batteries Including an Inorganic Electrolyte, and an Liquid crystalline polymer Fiber Electrolyte Membrane Comprising the Same

Abstract

The present invention relates to a polymer electrolyte composition for an all-solid-state battery and a polymer electrolyte membrane containing the same. The above composition for the polymer electrolyte comprises (a) a polymer; (b) a plasticizer; (c) a lithium salt; (d) an inorganic electrolyte; and (e) a photoinitiator. The electrolyte composition containing an inorganic electrolyte and the liquid crystal polymer (LCP) fiber electrolyte membrane according to the present invention are useful for all-solid-state batteries as they not only have excellent electrochemical stability and ion conductivity but also excellent charge-discharge life.

Description

Technology Field

[0001] The present invention relates to an electrolyte composition for a polymer all-solid-state battery containing an inorganic electrolyte and a liquid crystal polymer (LCP) fiber electrolyte membrane containing the same. Background Technology

[0002] Currently commercialized lithium-ion batteries are energy storage devices composed of a positive electrode active material, a negative electrode active material, a separator, and an electrolyte, which operate through electrochemical reactions as lithium ions move between the two electrodes using the electrolyte as a medium.

[0003] Lithium-ion batteries are widely used in commercially available portable electronic devices due to their high energy density, lack of memory effect, and low self-discharge even when not in use. Furthermore, leveraging their high energy density, their usage is also on the rise in the defense, automation systems, and aerospace industries.

[0004] As applications expand beyond existing small portable electronic devices to include electric vehicles and ESS, the importance of external effects such as high capacity, high output, and long lifespan, as well as high / low temperature performance, durability, and safety, is increasing.

[0005] To meet these requirements, the development of high-performance next-generation lithium-ion batteries is continuously progressing through the development and application of new materials across various aspects. Among these, research applying solid electrolytes is receiving the most attention in order to address the safety issues caused by the flammability, corrosiveness, thermal instability, and high-voltage vulnerability of organic electrolytes used in conventional lithium-ion batteries.

[0006] All-solid-state batteries replace flammable liquid electrolytes with inorganic solid electrolytes. Oxide-based and sulfide-based inorganic solid electrolytes are mainly used. Among these, sulfide-based solid electrolytes are promising because their lithium-ion conductivity is high enough to approach that of liquid electrolytes.

[0007] Korean Registered Patent No. 2456770 disclosed a method for manufacturing a solid electrolyte layer and an anode composite layer comprising a sulfide-based solid electrolyte, and an all-solid-state battery comprising the same, and Korean Published Patent No. 2023-0032092 disclosed a solid electrolyte membrane for an all-solid-state battery comprising a solid electrolyte in the form of particles and an additive with a linear structure, and an all-solid-state battery comprising the same.

[0008] Meanwhile, oxide-based solid electrolytes offer excellent stability, and sulfide-based solid electrolytes have excellent conductivity but suffer from low mass production potential; therefore, there are attempts to develop polymer-based solid electrolytes with high mass production potential.

[0009] Compared to liquid electrolytes, solid electrolytes offer advantages such as low flammability, high thermal stability, no risk of leakage, and a low risk of explosion. Furthermore, they can inhibit the growth of dendritic lithium due to their high mechanical strength and ability to prevent the migration of active materials. Solid electrolytes are generally classified into solid polymer electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0010] Following polyethylene oxide (PEO) polymers used with lithium salts, polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN) were applied as solid polymer electrolytes, but none of them 10 -4 There was a limitation in that it could not have an ionic conductivity of S / cm or higher.

[0011] Currently, Bolloré (France) and Factorial Energy (USA) are leading the development and commercialization of polymer electrolyte-based all-solid-state batteries as major players; however, due to limitations in temperature, charging speed, and application range, they are being used only in limited urban electric buses.

[0012] Therefore, there is a need to develop polymer electrolyte-based all-solid-state batteries with excellent electrochemical stability, ionic conductivity, and charge / discharge performance.

[0013] Accordingly, as a result of efforts to solve the above problems, the inventors confirmed that when a polymer electrolyte membrane is manufactured by coating an LCP fiber with a composition for a polymer electrolyte comprising polybutadiene urethane acrylate, a plasticizer, a lithium salt, and an inorganic electrolyte, the electrochemical stability, ion conductivity, and charge / discharge performance are excellent, and thus completed the present invention. The problem to be solved

[0014] The objective of the present invention is to provide a composition for a polymer electrolyte having excellent ionic conductivity and electrochemical stability.

[0015] Another objective of the present invention is to provide an electrolyte membrane having excellent ionic conductivity and electrochemical stability and significantly superior processability compared to PVDF membranes, and a method for manufacturing the same.

[0016] Another objective of the present invention is to provide an all-solid-state lithium secondary battery with excellent ionic conductivity and electrochemical stability. means of solving the problem

[0017] To achieve the above objective, the present invention provides a composition for a polymer electrolyte comprising (a) a polymer; (b) a plasticizer; (c) a lithium salt; (d) an inorganic electrolyte; and (e) a photoinitiator.

[0018] In the present invention, the polymer is characterized by being one or more selected from the group consisting of polybutadiene urethane acrylate, polyethylene glycol diacrylate, and polyethylene oxide.

[0019] In the present invention, the plasticizer is characterized by being one or more selected from the group consisting of ethylene carbonate and propylene carbonate.

[0020] In the present invention, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate (LiOTf), lithium (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide (LiPTFSI), lithium hexafluorophosphate (LiPF6), lithium hexafluoroantimonate (LiSbF6), lithium hexafluoroarsenate, It is characterized by being selected from the group consisting of LiAsF6), lithium difluoromethane sulfonate (LiC4F9SO3), lithium perchlorate (LiClO4), lithium aluminate (LiAlO2), lithium tetrachloroaluminate (LiAlCl4), lithium chloride (LiCl), and lithium iodide (LiI).

[0021] In the present invention, the inorganic electrolyte is characterized as being aluminum-doped lithium lanthanum zirconium oxide (Al-doped LLZO) or gallium-doped lithium lanthanum zirconium oxide (Ga-doped LLZO).

[0022] The present invention is characterized by comprising, based on 100 parts by weight of the lithium salt, 90 to 125 parts by weight of the polymer; 55 to 80 parts by weight of the inorganic electrolyte; 145 to 170 parts by weight of the plasticizer; and 5 to 9 parts by weight of the photoinitiator.

[0023] The present invention also provides a polymer electrolyte membrane characterized by having the composition for the polymer electrolyte coated on a liquid crystal polymer (LCP) fiber.

[0024] The present invention also provides a method for manufacturing a polymer electrolyte membrane comprising: (a) applying the polymer electrolyte composition to a liquid crystal polymer (LCP) fiber; and (b) irradiating light onto the liquid crystal polymer (LCP) fiber coated with the polymer electrolyte composition.

[0025] The present invention also provides an all-solid-state lithium secondary battery comprising: (b) a polymer electrolyte membrane; and (c) a cathode. Effects of the invention

[0026] The electrolyte composition containing an inorganic electrolyte and the liquid crystal polymer (LCP) fiber electrolyte membrane according to the present invention are useful for all-solid-state batteries as they not only have excellent electrochemical stability and ion conductivity but also excellent charge-discharge life. Brief explanation of the drawing

[0027] FIG. 1 is an explanatory diagram of a method for manufacturing a composite electrolyte membrane according to one embodiment of the present invention. Specific details for implementing the invention

[0028] In this invention, the aim was to confirm that when a polymer electrolyte membrane is manufactured by coating a polymer electrolyte composition of a specific composition onto a liquid crystal polymer (LCP) fiber, the electrochemical stability, ionic conductivity, charge / discharge life, and processability are excellent.

[0029] In the present invention, a composition for a polymer electrolyte comprising a polybutadiene urethane acrylate polymer and an inorganic electrolyte, AL-doped LLZO, was prepared, and a polymer electrolyte membrane was prepared by coating the composition onto a liquid crystal polymer (LCP) fiber. As a result of evaluating the ionic conductivity, electrochemical stability, and charge / discharge life of the prepared polymer electrolyte membrane, it was confirmed that the electrochemical stability, ionic conductivity, and charge / discharge life were all excellent.

[0030] Accordingly, in one aspect, the present invention relates to a composition for a polymer electrolyte comprising (a) a polymer; (b) a plasticizer; (c) a lithium salt; (d) an inorganic electrolyte; and (e) a photoinitiator.

[0031] In the present invention, the polymer is a photocurable polymer, and examples include polybutadiene urethane acrylate, polyethylene glycol diacrylate, polyethylene oxide, etc., but are not limited thereto. When the photocurable polymer is irradiated with ultraviolet (UV) light in the presence of a photoinitiator, a photopolymerization reaction is initiated to form photocrosslinking bonds.

[0032] The above polybutadiene urethane acrylate is not particularly limited, but it is preferable to use one having a molecular weight of 20,000 g / mol to 30,000 g / mol and a viscosity of 400,000 cps to 600,000 cps.

[0033] The above polyethylene glycol diacrylate is not particularly limited, but it is preferable to use one with a molecular weight of 600 to 1000 and a viscosity of 30 cps to 200 cps.

[0034] The above polyethylene oxide is not particularly limited, but one with a molecular weight of 20,000 to 500,000 g / mol can be used, and it is preferable to use one with a molecular weight of 100,000 to 300,000 g / mol.

[0035] In the present invention, the plasticizer is intended for improving ion conductivity and is characterized by comprising ethylene carbonate or propylene carbonate.

[0036] In the present invention, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate (LiOTf), lithium (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide (LiPTFSI), lithium hexafluorophosphate (LiPF6), lithium hexafluoroantimonate (LiSbF6), lithium hexafluoroarsenate (LiAsF6), Examples include, but are not limited to, lithium difluoromethane sulfonate (LiC4F9SO3), lithium perchlorate (LiClO4), lithium aluminate (LiAlO2), lithium tetrachloroaluminate (LiAlCl4), lithium chloride (LiCl), and lithium iodide (LiI).

[0037] In the present invention, the inorganic electrolyte may be exemplified by lithium lanthanum zirconium oxide, and preferably by aluminum-doped lithium lanthanum zirconium oxide (Al-doped LLZO), gallium-doped lithium lanthanum zirconium oxide (Ga-doped LLZO), etc.

[0038] In the present invention, examples of photoinitiators include, but are not limited to, 1-hydroxy-cyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]2-methyl-1-propanone, methylbenzoyl formate, α,α-dimethoxy-α-phenylacetophenone, 2-benzoyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4[(methylthio)phenyl]-2(4-morpholinyl)-1-propanone diphenyl(2,4,6-trimethylbenzoyl)-phosphine oxide, or bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide. In addition, the above photopolymerization initiator may be a currently commercially available product such as Irgacure 184, Irgacure 500, Irgacure 651, Irgacure 369, Irgacure 907, Darocur 1173, Darocur MBF, Irgacure 819, Darocur TPO, Esacure KIP 100F, etc. The above photoinitiator may be used alone or in a mixture of two or more different types.

[0039] In the present invention, based on 100 parts by weight of a lithium salt, the composition may comprise 90 to 125 parts by weight of the polymer; 55 to 80 parts by weight of the inorganic electrolyte; 145 to 170 parts by weight of the plasticizer; and 5 to 9 parts by weight of the photoinitiator. If the composition deviates from the range of the above composition, there is a risk that the ion conductivity, electrochemical stability, charge / discharge life, and coating properties may be reduced.

[0040] In another aspect, the present invention relates to a polymer electrolyte membrane characterized by having a composition for a polymer electrolyte of claim 1 coated on a liquid crystal polymer (LCP) fiber.

[0041] It is preferable to use a material made of liquid crystal polymer (LCP) fibers as a substitute for commonly used substrates such as PVDF, nonwoven fabric, PET, and screen mesh, in order to improve ion conductivity and impart processability. The liquid crystal polymer (LCP) fibers may have a thickness of 4㎛ to 12㎛.

[0042] In another aspect, the present invention relates to a method for manufacturing a polymer electrolyte membrane comprising the steps of: (a) applying a polymer electrolyte composition to a liquid crystal polymer (LCP) fiber; and (b) irradiating light onto the liquid crystal polymer (LCP) fiber coated with the polymer electrolyte composition.

[0043] As shown in Fig. 1, a polymer electrolyte composition was applied to a liquid crystal polymer (LCP) fiber, and then light was irradiated onto the liquid crystal polymer (LCP) fiber coated with the polymer electrolyte composition to produce a liquid crystal polymer (LCP) fiber-based polymer electrolyte membrane.

[0044] The above-mentioned polymer electrolyte composition is not particularly limited as long as it is a method capable of applying it to a liquid crystal polymer (LCP) fiber. For example, the application 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.

[0045] The wavelength of the ultraviolet (UV) light used for the curing reaction may be 250 to 450 nm.

[0046] The method for manufacturing a polymer electrolyte membrane according to the present invention may utilize a release film during the polymer electrolyte membrane manufacturing process. Examples of commonly used release films include silicone-coated PET, PE, OPP, etc., but are not limited thereto.

[0047] In another aspect, the present invention relates to an all-solid-state lithium secondary battery comprising (a) the polymer electrolyte membrane; (b) a positive electrode; and (c) a negative electrode.

[0048] The positive and negative electrodes applied to the above-mentioned all-solid-state lithium secondary battery may be those commonly used in the industry.

[0049] In the present invention, the anode comprises an anode active material layer, and the anode active material layer comprises an anode active material, a binder, and a conductive material.

[0050] The above-mentioned positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and examples include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), etc.

[0051] The above binder is a component that assists in the bonding of the positive active material and the conductive material, etc., and in bonding to the current collector, and comprises styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, and cellulose acetate. It may include one or more selected from the group consisting of butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0052] The above conductive material is not particularly limited as long as it prevents adverse reactions in the internal environment of the all-solid-state battery and has excellent electrical conductivity without causing chemical changes in the battery. Representative examples include graphite or conductive carbon. For instance, 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, or thermal black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum powder or nickel powder; conductive whiskies such as zinc oxide or potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives may be used alone or in a mixture of two or more types, but is not necessarily limited thereto.

[0053] 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 is lithium (Li + It may include a material capable of reversibly intercalating or deintercalating ), a material capable of reacting with lithium ions to reversibly form a lithium-containing compound, a lithium metal, or a lithium alloy.

[0054] The above lithium ion (Li + A material capable of reversibly inserting or deinserting ) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The lithium ions (Li +A material capable of reversibly forming a lithium-containing compound by reacting with ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of 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).

[0055] In addition, the binder and the conductive material are as described above in the positive active material layer.

[0056] [Example]

[0057] The present invention will be described in more detail below through examples. These examples are solely for illustrating the present invention, and it will be obvious to those skilled in the art that the scope of the present invention is not to be interpreted as being limited by these examples.

[0058] Examples 1–5: Composition for polymer electrolyte and preparation of polymer electrolyte membrane

[0059] A polymer electrolyte composition was prepared by mixing and stirring without a separate solvent in a glove box (MBraun) filled with argon gas, according to the composition of Table 1 below.

[0060] A polymer electrolyte composition was applied between release films, and then a polymer electrolyte membrane was prepared by UV irradiation at 250 nm to 450 nm.

[0061] Creation fee Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 LIFSI 100 100 100 100 100 100 100 AL DOPED LLZO(TDL) 65 55 80 65 65 65 65 Polybutadiene urethane acrylate (C003, BNTM) 110 110 110 90 125 110 110 Propylene carbonate 155 155 155 155 155 145 170 Photoinitiator (1173) 7 7 7 7 7 7 7

[0062] Comparative Examples 1–6: Composition for polymer electrolyte and preparation of polymer electrolyte membrane

[0063] A composition for a polymer electrolyte and a polymer electrolyte membrane were prepared in the same manner as in Example 1, except that the composition of Table 2 was used.

[0064] Creation fee Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 LIFSI 100 100 100 100 100 100 AL DOPED LLZO(TDL) 50 85 65 65 65 65 Polybutadiene urethane acrylate (C003, BNTM) 110 110 80 140 110 110 Propylene carbonate 155 155 155 155 130 180 Photoinitiator (1173) 7 7 7 7 7 7

[0065] Experimental Example 1: Evaluation of physical properties of a polymer electrolyte membrane prepared without a substrate

[0066] The physical properties of the polymer electrolyte membranes prepared in Examples 1 to 7 and Comparative Examples 1 to 6, which were prepared using a polymer electrolyte composition without a description, were evaluated, and the results are shown in Tables 3 and 4.

[0067] The evaluation methods for ionic conductivity, coating properties, and electrochemical stability are as follows.

[0068] Ion Conductivity

[0069] To measure the ionic conductivity of the polymer electrolyte membrane, the ionic conductivity of the electrolyte was measured using an electrochemical impedance analysis (EIS) method applying the following Equation 1.

[0070] [Equation 1]

[0071]

[0072] σ is the ionic conductivity, l is the thickness of the solid polymer electrolyte, R b is the measured bulk resistance, and A represents the area of ​​the solid polymer electrolyte.

[0073] Specifically, the polymer electrolyte membrane prepared in Example 1 was first inserted into a lithium-ion test cell purchased from Nara Cell. The AC impedance of the conductive cell was measured using WizEIS-1200 Premium (Manufacturer: Wizmac), and the ion conductivity was measured by applying conditions of a frequency range from 10 Hz to 100 kHz and an amplitude of 20 mV.

[0074] <Coating properties>

[0075] When a polymer electrolyte composition was applied between release films and then irradiated with UV, the coating surface condition of the polymer electrolyte composition and the thickness uniformity after UV curing were evaluated.

[0076] Electrochemical Stability

[0077] To evaluate the electrochemical stability of all-solid-state lithium secondary batteries, coin-type batteries were fabricated using Li metal, a blocking electrode, and a polymer electrolyte membrane. For the fabricated electrochemical cells, the electrochemical stability of the polymer electrolyte membrane was evaluated using linear sweep voltammetry (LSV) with a WizEIS-1200Premium (manufacturer: Wizmac) at 25°C. Voltage was applied in the range of 2.0 to 4.5 V at a scan rate of 0.5 mV / s.

[0078] Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Ionic conductivity (S / cm) 4.50E-04 3.53E-04 3.57E-04 5.11E-04 1.23E-04 1.11E-04 5.11E-04 Coating properties Coating surface condition (visual observation) Good Good Good Good Good Good Good Thickness (Thickness Gauge Evaluation) ± 5% ± 5% ± 5% ± 5% ± 5% ± 5% ± 5% Electrochemical stability (V) ≥ 4.1 ≥ 4.2 ≥ 4.1 ≥ 4.1 ≥ 4.1 ≥ 4.1 ≥ 4.1

[0079] From Table 3, it was found that the polymer electrolyte membranes of Examples 1 to 7 had excellent ionic conductivity and electrochemical stability, good impregnation (coating) of the polymer electrolyte composition, and uniform thickness.

[0080] Test items Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Ionic conductivity (S / cm) 6.73E-05 2.71E-04 4.28E-04 3.15E-05 5.67E-05 1.06E-05 Coating properties Coating surface condition (visual observation) commonly Insufficient Insufficient Insufficient Insufficient Bad Thickness (Thickness Gauge Evaluation) ± 8% ± 10% ± 6% ± 12% ± 10% ± 15% Electrochemical stability (V) ≥ 4.1 ≥ 4.1 ≥ 4.1 ≤ 3.5 ≥ 4.1 ≤ 3.8

[0081] From Table 4, Comparative Example 1 exhibited insufficient ionic conductivity, while Comparative Example 2 showed poor coating performance due to high mixed viscosity. Comparative Example 3 experienced dripping during coating due to low viscosity, and Comparative Example 4 exhibited poor coating performance and low ionic conductivity due to excessively high viscosity. Comparative Example 5 showed reduced ionic conductivity due to a low amount of plasticizer, and Comparative Example 6 exhibited poor electrochemical stability accompanied by dripping due to an excessive amount of plasticizer. .

[0082] Examples 8 and 9: Preparation of LCP fiber polymer electrolyte membranes

[0083] The polymer electrolyte composition prepared in Example 1 was prepared in the manner shown in FIG. 1 by Kurarey with an 8㎛ thickness (product name: Vecrus TM A polymer electrolyte membrane was prepared by applying it to an LCP fiber and irradiating it with UV light at 250 nm to 450 nm.

[0084] Comparative Examples 7–9: Preparation of polymer electrolyte membranes using substrates

[0085] The polymer electrolyte composition prepared in Example 1 was applied to PVDF (manufacturer: Lemon Co., Ltd.), 13 g / m² nonwoven fabric (manufacturer: Seoil P&C Co., Ltd.), and 13 g / m² paper (manufacturer: Seoil P&C Co., Ltd.) instead of LCP fibers, and a polymer electrolyte membrane was prepared by irradiating UV in the same manner as in Example 8.

[0086] Experimental Example 2: Evaluation of Physical Properties of Polymer Electrolyte Membrane Using a Substrate

[0087] The physical properties of the polymer electrolyte membranes prepared in Examples 8-9 and Comparative Examples 7-9 were evaluated, and the results are shown in Table 5.

[0088] Ionic conductivity and electrochemical stability were evaluated in the same way as in Experimental Example 1.

[0089] <Coating properties>

[0090] When a polymer electrolyte composition was applied between a release film containing a substrate (LCP fiber, PVDF, nonwoven fabric, paper) and subjected to UV irradiation, the surface condition of the electrolyte composition coating onto the substrate and the thickness uniformity after UV curing were evaluated.

[0091] division Example 8 Example 9 Comparative Example 7 Comparative Example 8 Comparative Example 9 Classification of entries LCP fiber LCP fiber PVDF non-woven fabric Hwaji Ionic conductivity (S / cm) 3.68E-04 3.41E-04 3.71E-04 1.51E-05 7.01E-06 Coating surface condition (visual observation) Good Good Good Good Insufficient Curl (electrolyte membrane curling) 3 mm or less 3 mm or less 7mm or more (too much curling) 3 mm or less 3 mm or less Electrochemical stability (V) ≥ 4.1 ≥ 4.1 ≥ 4.1 ≤ 3.8 ≤ 3.5

[0092] From Table 5, Examples 8 and 9 showed superior electrolyte impregnation, surface condition, ionic conductivity, and electrochemical stability with no curl for the liquid crystal polymer (LCP) fibers compared to Comparative Examples 7 to 9. On the other hand, Comparative Example 7 showed good electrolyte impregnation but was too prone to curling, and Comparative Examples 8 and 9 showed poorer ionic conductivity and electrochemical stability than the Examples, both being below 4V.

[0093] Foregoing, specific parts of the present invention have been described in detail. It will be apparent to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention. Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims

Claim 1 A composition for a polymer electrolyte comprising: (a) polybutadiene urethane acrylate; (b) one or more plasticizers selected from the group consisting of ethylene carbonate and propylene carbonate; (c) a lithium salt; (d) an inorganic electrolyte which is aluminum-doped lithium lanthanum zirconium oxide (Al-doped LLZO) or gallium-doped lithium lanthanum zirconium oxide (Ga-doped LLZO); and (e) a photoinitiator, wherein, based on 100 parts by weight of the lithium salt, the composition comprises 90 to 125 parts by weight of the polybutadiene urethane acrylate; 55 to 80 parts by weight of the inorganic electrolyte; 145 to 170 parts by weight of the plasticizer; and 5 to 9 parts by weight of the photoinitiator. Claim 2 delete Claim 3 delete Claim 4 In claim 1, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium trifluoromethanesulfonate (LiOTf), lithium (trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide (LiPTFSI), lithium hexafluorophosphate (LiPF6), lithium hexafluoroantimonate (LiSbF6), lithium hexafluoroarsenate, A composition for a polymer electrolyte characterized by being selected from the group consisting of LiAsF6), lithium difluoromethane sulfonate (LiC4F9SO3), lithium perchlorate (LiClO4), lithium aluminate (LiAlO2), lithium tetrachloroaluminate (LiAlCl4), lithium chloride (LiCl), and lithium iodide (LiI). Claim 5 delete Claim 6 delete Claim 7 A polymer electrolyte membrane characterized by having a composition for a polymer electrolyte of claim 1 coated on a liquid crystal polymer (LCP) fiber having a thickness of 4㎛ to 12㎛. Claim 8 (a) a step of applying the polymer electrolyte composition of claim 1 to a liquid crystal polymer (LCP) fiber having a thickness of 4 μm to 12 μm; and (b) a step of irradiating light onto the liquid crystal polymer (LCP) fiber coated with the polymer electrolyte composition, comprising a method for manufacturing a polymer electrolyte membrane. Claim 9 (a) a polymer electrolyte membrane of claim 7; (b) a positive electrode; and (c) a negative electrode, comprising an all-solid-state lithium secondary battery.

Images