Solid electrolyte and all-solid-state battery containing the same

Abstract

The present invention relates to a solid electrolyte for an all-solid-state battery and an all-solid-state battery including the same. The solid electrolyte includes a binder, and thus adhesion and strength are enhanced, and interface resistance is reduced, thereby improving ion conductivity.

Description

[Technical Field]

[0001] This application claims priority based on Korean Patent Application No. 10-2021-0180701 dated December 16, 2021, and all content disclosed in the documents of the said Korean Patent Application is included as part of this specification.

[0002] This invention relates to a solid electrolyte and an all-solid-state battery containing the same. [Background technology]

[0003] From the perspectives of battery capacity, safety, output, scaling up, and miniaturization, various types of batteries are currently being researched that can overcome the limitations of lithium-ion secondary batteries.

[0004] Typically, ongoing research is being conducted on metal-air batteries, which have a much larger theoretical capacity than current lithium-ion batteries; all-solid batteries, which do not pose an explosion risk in terms of safety; supercapacitors, which offer high output; NaS batteries or RFB (redox flow batteries), which are designed for larger sizes; and thin-film batteries, which are designed for ultra-miniaturization.

[0005] Among these, all-solid-state batteries refer to batteries that replace the liquid electrolyte used in existing lithium secondary batteries with a solid. Because they do not use flammable solvents in the battery, there is no risk of ignition or explosion due to the decomposition reaction of conventional electrolytes, thus significantly improving safety. In addition, since lithium metal or lithium alloy can be used as the negative electrode material, there is an advantage in that the energy density relative to the mass and volume of the battery can be dramatically improved.

[0006] While all-solid-state batteries offer advantages such as improved safety compared to conventional batteries using liquid electrolytes, there are still areas that need improvement in terms of energy density and lifespan.

[0007] To provide an all-solid-state battery with high energy density and long lifespan, it is necessary to improve the ionic conductivity of the solid electrolyte contained in the all-solid-state battery. However, there is a problem in that the ionic conductivity is somewhat reduced due to the interfacial resistance of the solid electrolyte.

[0008] Therefore, it is necessary to develop a technology that can reduce the interfacial resistance of the solid electrolyte and improve its ionic conductivity. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent Publication No. 2020-0118800 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] As a result of conducting multifaceted research to solve the aforementioned problems, the inventors confirmed that a solid electrolyte manufactured using a binder together with a solid-phase lithium dissociation material and a lithium salt has reduced interfacial resistance, thereby dramatically improving ionic conductivity.

[0011] Therefore, an object of the present invention is to provide a solid electrolyte for all-solid-state batteries with improved ionic conductivity.

[0012] Another object of the present invention is to provide an all-solid-state battery in which ionic conductivity is improved and energy density and lifespan characteristics are enhanced. [Means for solving the problem]

[0013] To achieve the above objective, the present invention provides a solid electrolyte comprising a solid-phase lithium dissociation material, a binder, and a lithium salt.

[0014] The present invention also provides an all-solid-state battery comprising a positive electrode, a negative electrode, and the solid electrolyte. [Effects of the Invention]

[0015] The solid electrolyte according to the present invention exhibits the effect that the adhesive force and strength are improved by the binder, the interfacial resistance is reduced, and thereby the ionic conductivity is improved.

[0016] Further, the all-solid-state battery according to the present invention exhibits the effect that the energy density and life characteristics are improved by the solid electrolyte with improved ionic conductivity.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic diagram showing the process of manufacturing a solid electrolyte according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described in more detail for the purpose of facilitating understanding of the present invention.

[0019] The terms and words used in this specification and the claims should not be construed as being limited to the ordinary or dictionary meanings. The inventor must interpret them in accordance with the meaning and concept consistent with the technical idea of the present invention, in accordance with the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way.

[0020] [[ID=…]]Solid electrolyte The present invention relates to a solid electrolyte for an all-solid-state battery, and the solid electrolyte includes a solid-phase lithium dissociation substance, a binder, and a lithium salt. The solid electrolyte can be a polymer solid electrolyte.

[0021] The solid electrolyte according to the present invention can be manufactured as an electrolyte membrane because the adhesive force and strength are enhanced by the binder, the interfacial resistance is reduced, and thereby the ionic conductivity is improved.

[0022] In the present invention, the solid-phase lithium dissociation material dissociates lithium salts to facilitate ion transfer, without reducing the ionic conductivity due to the lithium salts, and can improve electrical conductivity.

[0023] The solid-phase lithium dissociation material may contain one or more quinone compounds and cyanocarbon compounds, and more specifically, one or more selected from the group consisting of chloranil, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoethylene (TCNE), and trinitrofluorenone (TNF).

[0024] Furthermore, the solid-phase lithium dissociation material may be present in an amount of 20 to 90% by weight based on the total weight of the solid electrolyte. Specifically, the content of the solid-phase lithium dissociation material may be 30% or more by weight, 40% or more by weight, or 50% or more by weight, and may be 80% or less by weight, 70% or less by weight, or 60% or less by weight. If the content of the solid-phase lithium dissociation material is less than 20% by weight, lithium dissociation may not be sufficient, and the ionic conductivity of the solid electrolyte may decrease. If it exceeds 90% by weight, the content of lithium salt may decrease relatively, and the ionic conductivity may decrease.

[0025] In the present invention, the binder can improve ionic conductivity by improving the adhesive strength and strength of the solid electrolyte and reducing interfacial resistance.

[0026] The binder may be a polymer-based binder, for example, the binder may be styrene-butadiene rubber (SBR), acrylic styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, and It may contain one or more selected from the group consisting of cete propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride (PVDF), and poly(vinylidene fluoride)-hexafluoropropene, and preferably one or more selected from the group consisting of styrene-butadiene rubber (SBR), polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0027] Furthermore, the binder may be included in an amount of 3 to 40% by weight based on the total weight of the solid electrolyte. Specifically, the binder content may be 5% or more by weight, 10% or more by weight, or 15% or more by weight, and may be 40% or less by weight, 30% or less by weight, or 20% or less by weight. If the binder content is less than 3% by weight, there is a problem in that the manufacture of the electrolyte membrane is difficult, and if it exceeds 40% by weight, there is a problem in that the ionic conductivity decreases.

[0028] In the present invention, the lithium salt can impart ionic conductivity to the solid electrolyte and improve the ionic conductivity of the solid-phase lithium dissociated material.

[0029] The lithium salt can be used without particular restrictions as long as it is suitable for use as a lithium salt for secondary batteries. Specific examples include one or more selected from the group consisting of LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (Lithium bis(fluorosulfonyl)imide).

[0030] Furthermore, the lithium salt may be included in an amount of 10 to 80% by weight based on the total weight of the solid electrolyte. Specifically, the content of the lithium salt may be 20% or more by weight, 30% or more by weight, or 40% or more by weight, and may be 70% or less by weight, 60% or less by weight, or 50% or less by weight. If the content of the lithium salt is less than 10% by weight, the lithium source may be insufficient and the ionic conductivity of the solid electrolyte may decrease, and if it exceeds 80% by weight, the content of the lithium dissociated material in the solid phase may relatively decrease and the electrical conductivity may decrease.

[0031] In the present invention, the solid electrolyte may be in the form of a solid electrolyte membrane. In this case, the thickness of the solid electrolyte may be 5 μm to 150 μm. If the thickness of the solid electrolyte is less than 5 μm, it may have low strength and be difficult to perform as an insulating film, or the processability may be reduced. If it exceeds 150 μm, the energy density may be low.

[0032] In the present invention, the solid electrolyte may not contain an ionically conductive polymer in addition to the solid-phase lithium dissociation material, binder, and lithium salt described above, and more specifically, it may consist of a solid-phase lithium dissociation material, binder, and lithium salt. Because the solid electrolyte of the present invention does not contain a separate ionically conductive polymer, the ionic conduction mechanisms of the polymers do not differ, and therefore the synergistic effect of ionic conductivity can be increased.

[0033] Method for producing solid electrolytes The present invention also relates to a method for producing a solid electrolyte, the method for producing the solid electrolyte comprising: (S1) coating a substrate with a mixture containing a solid-phase lithium dissociation material, a binder, and a lithium salt; (S2) drying the coating layer obtained in step (S1); and (S3) separating the coating layer from the substrate after drying in step (S2) to obtain a solid electrolyte.

[0034] The method for producing a solid electrolyte according to the present invention will be described in more detail below, step by step.

[0035] In the present invention, in step (S1), a mixture containing a solid-phase lithium dissociation material, a binder, and a lithium salt can be coated onto a substrate. The types and contents of the solid-phase lithium dissociation material, binder, and lithium salt are as described above.

[0036] Figure 1 is a schematic diagram showing the process of forming a coating layer for solid electrolyte production on a substrate according to one embodiment of the present invention.

[0037] Referring to Figure 1, a solid-phase lithium dissociation material is dissolved in a solvent to produce a solid-phase lithium dissociation material solution (Li dissociation material / Li salt solution), and then a lithium salt is mixed in to obtain the first mixture (Li dissociation material / Li salt solution).

[0038] Subsequently, a binder is mixed with the first mixture (lithium dissociation material / lithium salt solution) to obtain a second mixture (lithium dissociation material / lithium salt / binder solution), which can then be coated onto a substrate.

[0039] The solvent is not particularly limited as long as it can dissolve the solid-phase lithium dissociated material, binder, and lithium salt. For example, the solvent may be dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one or more of these may be used. The amount of solvent used can be determined by considering the thickness of the coating layer, the physical properties of the solid electrolyte produced, etc., in order to dissolve or disperse the solid-phase lithium dissociated material, binder, and lithium salt.

[0040] The substrate is not particularly limited as long as it is a substrate used in a coating process for forming a solid electrolyte. For example, the substrate may be a glass substrate or a plastic substrate, and the plastic substrate may be polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, etc.

[0041] Furthermore, 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, but is not limited to these as long as it is a coating method that can form a coating layer on the substrate.

[0042] In the present invention, in step (S2), the coating layer obtained in step (S1) can be dried.

[0043] The drying method is not particularly limited as long as it is a drying method that can evaporate the solvent contained in the coating layer and form a coating layer for solid electrolyte formation. For example, the drying may be carried out at a temperature of 100°C or lower.

[0044] In the present invention, in step (S3), after drying in step (S2), the coating layer can be separated from the substrate to obtain a solid electrolyte.

[0045] all solid state battery The present invention also relates to an all-solid-state battery comprising the solid electrolyte described above, the all-solid-state battery may include a positive electrode, a negative electrode, and the solid electrolyte interposed between them.

[0046] In the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector.

[0047] The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material.

[0048] The cathode active material is not particularly limited as long as it can reversibly occlude and release lithium ions. Examples include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni Co y Mn z M v O2 (in the above formula, M is any one selected from the group consisting of Al, Ga, and In or two or more of these elements; 0.3 ≦ x < 1.0, 0 ≦ y, z ≦ 0.5, 0 ≦ v ≦ 0.1, and x + y + z + v = 1), Li(Li a M b-a-b’ M’ b’ )O 2-c A c (in the above formula, 0 ≦ a ≦ 0.2, 0.6 ≦ b ≦ 1, 0 ≦ b’ ≦ 0.2, 0 ≦ c ≦ 0.2; M includes one or more selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M’ is one or more selected from the group consisting of Al, Mg, and B, and A is one or more selected from the group consisting of P, F, S, and N.) and other layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y O4 (where y is 0 - 0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; Ni-site type lithium nickel oxides represented by the chemical formula LiNi 1-y MyO2 (where M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga and y = 0.01 - 0.3); lithium manganese composite oxides represented by the chemical formula LiMn 2-y M y O2 (where M = Co, Ni, Fe, Cr, Zn, or Ta and y = 0.01 - 0.1) or Li2Mn3MO8 (where M = Fe, Co, Ni, Cu, or Zn); LiMn2O4 in which part of the Li in the chemical formula is substituted with alkaline earth metal ions; disulfide compounds; Fe2(MoO4)3, etc. can be mentioned, but it is not limited to only these.

[0049] The positive electrode active material can be included 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 or 50% or more by weight, and 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 be insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0050] Furthermore, the binder is a component that helps to bond the positive electrode active material to conductive materials and to the current collector, and includes styrene-butadiene rubber, acrylic styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile-butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, and polyacrylonitrile. The binder may include one or more selected from the group consisting of polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethylcellulose, hydroxypropylcellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include one or more selected from the group consisting of styrene-butadiene rubber, polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride.

[0051] Furthermore, the binder can be included 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, which may result in a lower battery capacity.

[0052] 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 can be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, 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; which can be used alone or in mixtures of two or more, but are not necessarily limited to these.

[0053] The conductive material can typically 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, or 1% or more by weight, and may be 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 (more than 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 significantly limited, and conventional methods known in the art, such as coating the positive electrode active material, can be used.

[0054] 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.

[0055] 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., and aluminum-cadmium alloys can be used as the positive electrode current collector.

[0056] The positive electrode current collector may have a fine uneven surface or a three-dimensional porous structure to enhance the bonding force with the positive electrode active material layer. This allows the positive electrode current collector to take on a variety of forms, such as film, sheet, foil, mesh, net, porous material, foam, nonwoven fabric, etc.

[0057] 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 positive electrode current collector to improve the positive 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. Specifically, examples include acetonitrile, methanol, ethanol, tetrahydropyran, water, isopropyl alcohol, etc.

[0058] In the present invention, the negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material, a binder, and a conductive material.

[0059] The aforementioned negative electrode active material is lithium ion (Li +This may include materials that can be reversibly intercalated or deintercalated, materials that can react with lithium ions to reversibly form lithium-containing compounds, lithium metals, or lithium alloys.

[0060] The aforementioned lithium ion (Li + A substance that can reversibly insert or remove lithium ions (Li) may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. + Substances that can reversibly form lithium-containing compounds by reacting with ) may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) with a metal selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0061] Preferably, the negative electrode active material may be a lithium metal, specifically in the form of a lithium metal thin film or lithium metal powder.

[0062] The negative electrode active material can be included in an amount of 40 to 80% by weight based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40% or more by weight or 50% or more by weight, and may be 70% or less by weight or 80% or less by weight. If the content of the negative electrode active material is less than 40% by weight, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may become insufficient, and if it exceeds 80% by weight, the mass transfer resistance may increase.

[0063] Furthermore, the binder is the same as described above for the positive electrode active material layer.

[0064] Furthermore, the conductive material is the same as that described above for the positive electrode active material layer.

[0065] 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 can 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 can be made in a variety of forms, such as films, sheets, foils, nets, porous materials, foams, nonwoven fabrics, etc., with fine irregularities formed on the surface.

[0066] The method for manufacturing the negative electrode is not particularly limited, and it can be manufactured by forming a negative electrode active material layer on a negative electrode current collector using a layer or film formation method commonly used in the industry. For example, methods such as crimping, coating, and vapor deposition can 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.

[0067] The manufacturing of the all-solid-state battery having the above-described configuration is not particularly limited in this invention, and known methods can be used.

[0068] In the manufacturing of the all-solid-state battery of the present invention, electrodes including a positive electrode and a negative electrode are arranged, and then the cells are assembled by pressure molding.

[0069] The assembled cells are then placed inside the outer packaging material and sealed by heat sealing or the like. Laminate packs made of aluminum, stainless steel, etc., and cylindrical or rectangular metal containers are very suitable as outer packaging materials.

[0070] The following are preferred embodiments to aid in understanding the present invention. However, these embodiments are merely illustrative of the present invention, and it will be obvious to those skilled in the art that various changes and modifications are possible within the scope of the present invention and the technical concept, and that such changes and modifications will naturally fall within the scope of the attached claims.

[0071] Examples In the following examples and comparative examples, solid electrolytes for all-solid-state batteries were manufactured using the weight ratios of solid-phase lithium dissociated material, lithium salt, and binder as shown in Table 1 below.

[0072] [Table 1]

[0073] Example 1 (1) Manufacturing of solid electrolytes A lithium dissociation material solution was prepared by dissolving chloranil, a solid-phase lithium dissociation material, in a solvent, and then mixing it with LiTFSI, a lithium salt, to obtain a first mixture. NMP was used as the solvent. A second mixture was formed by mixing PVDF, a binder, with the first mixture, and then the second mixture was bar-coated onto one surface of polyethylene terephthalate to form a coating layer. As shown in Table 1, the weight ratio of the solid-phase lithium dissociation material, lithium salt, and binder was 0.5:1:0.3.

[0074] The coating layer was dried in a vacuum oven at 100°C for 24 hours, and then separated from the substrate to produce a solid electrolyte.

[0075] Example 2 A solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of the lithium dissociation material, lithium salt, and binder was set to 0.5:1:0.6.

[0076] Example 3 A solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of the lithium dissociation material, lithium salt, and binder was set to 0.75:0.75:0.3.

[0077] Example 4 A solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of the lithium dissociation material, lithium salt, and binder was set to 1:0.5:0.3.

[0078] Example 5 A solid electrolyte was prepared in the same manner as in Example 1, except that DDQ was used as the lithium dissociation material, and the weight ratio of the lithium dissociation material, lithium salt, and binder was 1:0.5:0.3.

[0079] Example 6 A solid electrolyte was prepared in the same manner as in Example 1, except that LiFSI was used as the lithium salt and the weight ratio of the lithium dissociation material, lithium salt, and binder was 1:0.5:0.3.

[0080] Comparative Example 1 A solid electrolyte was prepared in the same manner as in Example 1, except that PEO was used instead of the lithium dissociation material, no binder was used, and the weight ratio of PEO to lithium salt was 0.5:1.

[0081] Comparative Example 2 A solid electrolyte was prepared in the same manner as in Example 1, except that no binder was used and the weight ratio of lithium dissociated material to lithium salt was set to 0.5:1.

[0082] Comparative Example 3 A solid electrolyte was prepared in the same manner as in Example 1, except that the weight ratio of the lithium dissociation material, lithium salt, and binder was set to 0.5:1:0.9.

[0083] Comparative Example 4 A solid electrolyte was prepared in the same manner as in Example 1, except that PEO was added as an ionic conductive polymer, and the weight ratio of the ionic conductive polymer, lithium dissociated material, lithium salt, and binder was 1.8:0.5:1:0.3.

[0084] Experimental Example 1: Evaluation of Solid Electrolytes The solid electrolytes produced in the examples and comparative examples were subjected to ionic conductivity tests as described below, and the results are shown in Table 2.

[0085] (1) Ionic conductivity After bringing the solid electrolyte sample into contact with a SUS electrode of the same surface area, an AC voltage was applied through the electrodes on both sides of the sample at room temperature. The applied voltage was set to an amplitude range of 0.01 Hz to 1 MHz, and the impedance was measured using a BioLogic VMP3. The resistance of the solid electrolyte was determined from the intersection points Rb where the semicircles and straight lines of the measured impedance trajectories meet the real axis, and the ionic conductivity of the solid electrolyte was calculated from the sample's width and thickness.

[0086] [Formula 1]

number

[0087] [Table 2]

[0088] As shown in Table 2, the present invention demonstrated performance far exceeding that of existing solid electrolyte membranes in terms of ionic conductivity. In particular, the binder content is important; however, in Comparative Example 2, which contained no binder, it could not be manufactured as a solid electrolyte membrane, and in Comparative Example 3, where the binder content was very high, the resistance increased, resulting in very low ionic conductivity. Furthermore, even when mixed with existing solid electrolytes, the synergistic effect on ionic conductivity was minimal because the ion conduction mechanisms were different.

[0089] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is of course possible for a person with ordinary skill in the art to make various modifications and variations within the equivalent scope of the technical concept of the present invention and the claims described below.

Claims

1. It comprises a solid-phase lithium dissociation material, a binder, and a lithium salt. The binder consists of one or more selected from the group consisting of styrene-butadiene rubber (SBR), polytetrafluoroethylene, carboxymethylcellulose, polyacrylic acid, lithium polyacrylate, and polyvinylidene fluoride. The binder is a solid electrolyte that is contained in an amount of 10% to 30% by weight, based on the total weight of the solid electrolyte.

2. The solid electrolyte according to claim 1, wherein the lithium dissociation material of the solid phase comprises one or more selected from the group consisting of chloranil, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetracyanoethylene (TCNE), and trinitrofluorenone (TNF).

3. The solid electrolyte according to claim 1, wherein the solid-phase lithium dissociated material is present in an amount of 20 to 90% by weight based on the total weight of the solid electrolyte.

4. The solid electrolyte according to claim 1, wherein the lithium salt comprises one or more selected from the group consisting of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) and LiFSI (lithium bis(fluorosulfonyl)imide).

5. The solid electrolyte according to claim 1, wherein the lithium salt is present in an amount of 10 to 80% by weight based on the total weight of the solid electrolyte.

6. The solid electrolyte according to claim 1, wherein the solid electrolyte is in the form of a solid electrolyte membrane.

7. The solid electrolyte according to claim 6, wherein the solid electrolyte membrane has a thickness of 5 μm to 150 μm.

8. The solid electrolyte according to claim 1, wherein the solid electrolyte does not contain a polymer having ionic conductivity.

9. The solid electrolyte according to claim 1, wherein the solid electrolyte comprises a solid-phase lithium dissociation material, a binder, and a lithium salt.

10. A solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte according to any one of claims 1 to 9.

Images