Solid electrolyte membrane and all-solid-state battery including the same

Abstract

The present invention relates to a solid electrolyte membrane for an all-solid-state battery, which comprises a particulate solid electrolyte and a linear additive, and an all-solid-state battery including the same.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0114511, filed August 30, 2021, and incorporates all of the contents disclosed in the documents of that Korean patent application as part of this specification.

[0002] The present invention relates to a solid electrolyte membrane and an all-solid-state battery including the same. [Background technology]

[0003] A secondary battery is a device that converts external electrical energy into chemical energy, stores it, and generates electricity when needed. It is also called a rechargeable battery because it can be recharged multiple times. Commonly used secondary batteries include lead-acid batteries, nickel-cadmium batteries (NiCd), nickel-metal hydride batteries (NiMH), and lithium secondary batteries. Secondary batteries offer both economical and environmental advantages over disposable primary batteries.

[0004] Meanwhile, as wireless communication technology continues to develop, portable devices and automobile accessories are being required to be lighter, thinner, and smaller, increasing the demand for secondary batteries to be used as energy sources for these devices. In particular, as hybrid and electric vehicles are being commercialized to prevent environmental pollution, research is gaining momentum to use secondary batteries in these next-generation automobile batteries to reduce manufacturing costs and weight and extend life. Among various secondary batteries, lithium secondary batteries have recently been attracting attention due to their light weight, high energy density, operating potential, and long cycle life.

[0005] In general, a lithium secondary battery is manufactured by installing an electrode assembly including a negative electrode, a positive electrode, and a separator inside a cylindrical or rectangular metal can or a pouch-type case made of an aluminum laminate sheet, and injecting an electrolyte into the electrode assembly.

[0006] However, lithium secondary batteries require a case with a certain amount of space, such as a cylindrical, square, or pouch-shaped case, which limits the development of various portable devices. Therefore, a new type of lithium secondary battery that can be easily modified is needed. In particular, an electrolyte that does not leak and has excellent ionic conductivity is needed as the electrolyte contained in the lithium secondary battery.

[0007] Conventionally, electrolytes for lithium secondary batteries have mainly been liquid electrolytes in which lithium salts are dissolved in non-aqueous organic solvents. However, such liquid electrolytes are likely to cause electrode material degradation and organic solvent volatilization, and are susceptible to combustion or explosion due to temperature increases in the surrounding area and the battery itself, and to leakage, making it difficult to realize various types of highly safe lithium secondary batteries.

[0008] On the other hand, all-solid-state batteries using a solid electrolyte have the advantage that they do not use organic solvents and therefore allow the electrode assembly to be manufactured in a safe and simple manner.

[0009] However, all-solid-state batteries have limitations in that their actual energy density and output are lower than those of conventional lithium secondary batteries that use liquid electrolytes. Because an electrolyte membrane containing a solid electrolyte is located between the positive and negative electrodes, all-solid-state batteries are larger and heavier than conventional lithium secondary batteries, resulting in lower energy density per volume and energy density per weight. If the electrolyte membrane is made thinner to prevent this, a short circuit between the positive and negative electrodes may occur.

[0010] Therefore, there is a need to develop an electrolyte membrane that has excellent mechanical strength, can maintain a stable state between the electrodes, and has excellent ionic conductivity. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Korean Patent Publication No. 10-2016-0115912 [Patent Document 2] Korean Patent Registration No. 10-1512170 Summary of the Invention [Problem to be solved by the invention]

[0012] Therefore, the present inventors have conducted extensive research to solve the above problems, and have found that when a solid electrolyte membrane contains an additive having a linear structure, the ionic conductivity and strength of the thin-film solid electrolyte membrane can be improved, thereby completing the present invention.

[0013] Therefore, an object of the present invention is to provide a solid electrolyte membrane for an all-solid-state battery that has excellent ionic conductivity and strength.

[0014] Another object of the present invention is to provide an all-solid-state battery including the solid electrolyte membrane. [Means for solving the problem]

[0015] In order to achieve the above purpose, The present invention provides a solid electrolyte membrane for an all-solid-state battery, which comprises a particulate solid electrolyte and an additive having a linear structure.

[0016] The present invention also provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, The solid electrolyte membrane provides an all-solid-state battery that is the solid electrolyte membrane of the present invention. [Effects of the Invention]

[0017] The solid electrolyte membrane for an all-solid-state battery of the present invention contains an additive with a linear structure, and therefore has excellent mechanical strength even at a thickness of 50 μm or less, and is effective in improving energy density and ionic conductivity. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing a solid electrolyte membrane for an all-solid-state battery of the present invention. FIG. [Figure 2]FIG. 1 is a diagram showing a solid electrolyte membrane for an all-solid-state battery containing a binder of Comparative Example 2. [Figure 3] FIG. 10 is a diagram showing a solid electrolyte membrane for an all-solid-state battery including a separator of Comparative Example 4. [Figure 4] 1 is a photograph of the solid electrolyte membrane of Example 1. [Figure 5] 1 is an SEM photograph of the surface of the solid electrolyte membrane of Example 1. [Figure 6] 1 is a photograph of the solid electrolyte membrane of Comparative Example 1. [Figure 7] 1 is a photograph of the surface of the solid electrolyte membrane of Comparative Example 1. [Figure 8] 1 is an SEM photograph of the surface of the solid electrolyte membrane of Comparative Example 1. [Figure 9] 1 is a photograph of the solid electrolyte membrane of Comparative Example 2. [Figure 10] 1 is a photograph of the solid electrolyte membrane of Comparative Example 3. [Figure 11] 1 is a photograph of the surface of the solid electrolyte membrane of Comparative Example 4. [Figure 12] 1 is an SEM photograph of the surface of the solid electrolyte membrane of Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will now be described in more detail.

[0020] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary and dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventor himself / herself can appropriately define the concept of the term in order to explain the invention in the best possible way.

[0021] The terms used in the present invention are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the terms "comprise" or "have" and the like are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0022] Lithium secondary batteries have been used in small devices such as mobile phones and laptops, but recently their application has expanded to medium and large devices such as electric vehicles and energy storage devices. In these cases, the operating environment is harsher than in small devices, and more batteries must be used, so they must have excellent performance and stability.

[0023] Currently, most commercially available lithium secondary batteries use a liquid electrolyte in which lithium salt is dissolved in an organic solvent. The organic solvent contained in the liquid electrolyte is volatile and flammable, which poses a potential risk of fire and explosion, and is susceptible to leakage, resulting in a lack of long-term reliability.

[0024] As a result, the development of all-solid-state batteries, which replace the liquid electrolyte of lithium secondary batteries with a solid electrolyte, is progressing. Because all-solid-state batteries do not contain volatile organic solvents, they are free from the risk of explosion or fire, and are attracting attention as batteries that are economical, highly productive, and capable of producing high-power batteries.

[0025] In all-solid-state batteries, solid electrolytes require high ionic conductivity and mechanical strength to be processable. However, ensuring mechanical strength inevitably requires an increase in the thickness of the solid electrolyte membrane, which reduces energy density. Therefore, to ensure mechanical strength while reducing the thickness of the solid electrolyte membrane, a solid electrolyte membrane with large pores and high porosity is required, even at a thickness of 50 μm or less. However, because porosity has a trade-off with strength and thickness, it is difficult to manufacture a thin membrane with high porosity.

[0026] Therefore, the present invention aims to provide a thin solid electrolyte membrane excellent in mechanical strength and ionic conductivity by incorporating a linear structure additive into a solid electrolyte membrane for an all-solid-state battery.

[0027] The present invention relates to a solid electrolyte membrane for an all-solid-state battery, which comprises a particulate solid electrolyte and an additive having a linear structure.

[0028] The linear-structured additive acts as a frame to maintain the mechanical strength of the solid electrolyte membrane made of particulate solid electrolyte. Because the linear-structured additive is uniformly distributed in the solid electrolyte membrane, the solid electrolyte membrane can maintain excellent mechanical strength even when thinned.

[0029] The linear additive may be in the form of polymer fibers. The type of polymer may be any fibrous polymer commonly used in the art. For example, the additive may include at least one selected from the group consisting of polyphenylene sulfide, polyether ether ketone, polyethylene terephthalate, polyimide, polyamide, polysulfone, polyvinylidene fluoride, polyacrylonitrile, polyethylene, and polypropylene, and preferably polyphenylene sulfide. Polyphenylene sulfide is a super engineering plastic and is most preferred because it has excellent physical properties such as strength, flame retardancy, heat resistance, and chemical resistance, thereby improving the safety of the solid electrolyte membrane.

[0030] The linear structure additive may have an average diameter of 50 nm to 5 μm, preferably 100 nm to 3 μm, and an average length of 500 nm to 5 mm, preferably 500 nm to 1 mm. The linear structure additive may have a ratio of the average length to the average diameter (average length / average diameter) of 5 to 1000, preferably 10 to 200. By having the above diameter and length, improved mechanical strength of the solid electrolyte membrane can be obtained.

[0031] The linear-structured additive of the present invention does not function as a binder connecting particulate solid electrolyte particles, but rather as a frame that maintains the structure of the solid electrolyte membrane. Therefore, since the linear-structured additive is not coated on the surface of the particulate solid electrolyte, it can exhibit improved ionic conductivity compared to solid electrolyte membranes that contain binders. Furthermore, since the linear-structured additive is included in a lower content than that of conventional solid electrolyte membranes, it can increase the content of particulate solid electrolyte particles, thereby exhibiting improved ionic conductivity of the solid electrolyte membrane.

[0032] That is, the linear structure additive may be present in an amount of 0.5, 1, 2, 3, or 4 or more, and 1, 2, 3, 4, or 5 wt % or less, based on the total weight of the solid electrolyte membrane. Specifically, it may be 0.5 to 5 wt %, preferably 1 to 3 wt %. Within this range, the solid electrolyte membrane can exhibit excellent mechanical strength and ionic conductivity. If the linear structure additive is present in an amount less than 0.5 wt %, the mechanical strength of the solid electrolyte membrane decreases, making it difficult to maintain the structure of the solid electrolyte membrane. If the linear structure additive is present in an amount greater than 5 wt %, the content of particulate solid electrolyte decreases, resulting in a significant decrease in the ionic conductivity of the solid electrolyte membrane.

[0033] The solid electrolyte membrane for an all-solid-state battery of the present invention contains the additive having a linear structure described above, and thus can provide a solid electrolyte membrane that has excellent mechanical strength and ionic conductivity despite being a thin film with a small thickness.

[0034] More specifically, the ionic conductivity of the solid electrolyte membrane for an all-solid-state battery of the present invention may be 0.01 to 10 mS / cm, preferably 0.1 to 5 mS / cm.

[0035] In the present invention, the mechanical strength of the solid electrolyte membrane for an all-solid-state battery means the degree to which the solid electrolyte membrane for an all-solid-state battery can maintain its structure (free-standing).

[0036] The thickness of the solid electrolyte membrane for an all-solid-state battery may be 5 to 50 μm, preferably 10 to 30 μm. As described above, the thickness of the thin film can provide an effect of improving energy density.

[0037] The particulate solid electrolyte may be a sulfide-based solid electrolyte or a polymer-based solid electrolyte, and preferably a particulate sulfide-based solid electrolyte.

[0038] The sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic. Non-limiting examples of such sulfide-based solid electrolytes include Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and may include one or more of these. However, the sulfide-based solid electrolyte is not limited thereto.

[0039] The polymer solid electrolyte is a composite of lithium salt and polymer resin, i.e., a polymer electrolyte material formed by adding polymer resin to solvated lithium salt, and has a capacity of about 1×10 -7 S / cm or more, preferably about 1 × 10 -5 It can exhibit ionic conductivity of S / cm or more.

[0040] Non-limiting examples of the polymer resin include polyether polymers, polycarbonate polymers, acrylate polymers, polysiloxane polymers, phosphazene polymers, polyethylene derivatives, alkylene oxide derivatives such as polyethylene oxide, phosphate ester polymers, polyagitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers containing ionic dissociation groups, etc. The polymer electrolyte may include one or more of the following polymer resins: branched copolymers in which a polyethylene oxide (PEO) main chain is copolymerized with an amorphous polymer such as PMMA, polycarbonate, polysiloxane (pdms), and / or phosphazene, a comb-like polymer, and a crosslinked polymer.

[0041] In the electrolyte of the present invention, the lithium salt is an ionizable lithium salt, and Li + X - The anion of such a lithium salt is not particularly limited, but may be F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C -, (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - Examples include:

[0042] The particulate solid electrolyte may be contained in an amount of 95 to 99.5 wt %, preferably 97 to 99 wt %, based on the total weight of the solid electrolyte membrane.

[0043] The present invention also relates to an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween, and the solid electrolyte membrane may be the solid electrolyte membrane of the present invention described above.

[0044] The all-solid-state battery is a lithium secondary battery, and is not limited to a positive electrode or a negative electrode, and may be a lithium-air battery, a lithium oxide battery, a lithium-sulfur battery, or a lithium metal battery.

[0045] The positive electrode may include a positive electrode current collector and a positive electrode active material coated on one or both surfaces of the positive electrode current collector.

[0046] The positive electrode current collector is used to support the positive electrode active material and is not particularly limited as long as it has excellent conductivity and is electrochemically stable in the voltage range of a lithium secondary battery. For example, the positive electrode current collector may be made of any metal selected from the group consisting of copper, aluminum, stainless steel, titanium, silver, palladium, nickel, alloys thereof, and combinations thereof. The stainless steel may be surface-treated with carbon, nickel, titanium, or silver. The alloy may preferably be an aluminum-cadmium alloy. Other examples include calcined carbon, a non-conductive polymer surface-treated with a conductive material, or a conductive polymer.

[0047] The positive electrode current collector may have fine irregularities on its surface to strengthen the bonding force with the positive electrode active material, and may be in various forms such as a film, a sheet, a foil, a mesh, a net, a porous body, a foam, or a nonwoven fabric.

[0048] The positive electrode active material may include a positive electrode active material, a conductive material, and a binder.

[0049] The positive electrode active material may vary depending on the type of all-solid-state battery. For example, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; 1+x Mn 2-x O4 (0≦x≦0.33), lithium manganese oxides such as LiMnO3, LiMn2O3, and LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, and Cu2V2O7; chemical formula LiNi 1-x M x Ni-site lithium nickel oxide represented by O2 (M = Co, Mn, Al, Cu, Fe, Mg, B, or Ga; 0.01≦x≦0.3); chemical formula: LiMn 2-x M x Lithium manganese composite oxides represented by O2 (M = Co, Ni, Fe, Cr, Zn, or Ta; 0.01 ≤ x ≤ 0.1) or Li2Mn3MO8 (M = Fe, Co, Ni, Cu, or Zn); LiNi x Mn 2-x Lithium manganese composite oxide with a spinel structure represented by O4; LiCoPO4; LiFePO4; elemental sulfur (S8); Li2S n (n=1), organic sulfur compounds or carbon-sulfur polymers (C2S x ) n The compound may include, but is not limited to, sulfur-based compounds such as: x=2.5 to 50, n=2.

[0050] The conductive material is a material that electrically connects the electrolyte and the positive electrode active material and serves as a path for electrons to move from a current collector to the positive electrode active material. Any conductive material may be used without limitation as long as it does not cause a chemical change in a lithium secondary battery and has porosity and conductivity.

[0051] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, or carbon fiber; metallic fibers such as metal mesh; metallic powders such as copper, silver, nickel, or aluminum; or organic conductive materials such as polyphenylene derivatives. The conductive materials may be used alone or in combination.

[0052] Currently, commercially available conductive materials include acetylene black (products of Chevron Chemical Company or Gulf Oil Company, etc.), Ketjen Black, EC series (products of Armak Company), Vulcan XC-72 (products of Cabot Company), and Super P (products of MMM). Examples include acetylene black, carbon black, and graphite.

[0053] The positive electrode may further include a binder, which enhances the binding strength between components constituting the positive electrode and between the components and the current collector. Any binder known in the art may be used.

[0054] For example, the binder may be one or a mixture or copolymer of two or more selected from the group consisting of: fluororesin-based binders including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); rubber-based binders including styrene butadiene rubber (SBR), acrylonitrile butadiene rubber, and styrene-isoprene rubber; cellulose-based binders including carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; polyalcohol-based binders; polyolefin-based binders including polyethylene and polypropylene; polyimide-based binders; polyester-based binders; and silane-based binders.

[0055] The negative electrode may include a negative electrode current collector and a negative electrode active material disposed on the negative electrode current collector. Similarly to the positive electrode, the negative electrode may include a conductive material and a binder, as needed. The negative electrode current collector, conductive material, and binder are as described above.

[0056] The negative electrode active material is a lithium ion (Li + Any material can be used as long as it can reversibly store (intercalate) or release (deintercalate) lithium ions, or can react with lithium ions to reversibly form a lithium-containing compound.

[0057] For example, the negative electrode active material may be one or more carbon-based materials selected from the group consisting of crystalline artificial graphite, crystalline natural graphite, amorphous hard carbon, low-crystalline soft carbon, carbon black, acetylene black, Ketjen black, Super P, graphene, and fibrous carbon; Si-based materials, Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me1-x Me y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≤ 1; 1 ≤ y ≤ 3; 1 ≤ z ≤ 8), etc. metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxides; lithium titanium oxides, etc. can be included, but are not limited to only these.

[0058] The production of the all-solid-state battery is not particularly limited in the present invention, and known methods can be used.

[0059] As an example, after arranging a solid electrolyte membrane between the positive electrode and the negative electrode, this is compression-molded to assemble a cell. After installing the assembled cell inside an exterior material, it is sealed by heat compression or the like. As the exterior material, laminated packs such as aluminum and stainless steel, and metal containers such as cylindrical and rectangular ones can be used.

[0060] As an example, the electrodes of the positive electrode and the negative electrode are manufactured in the form of a slurry composition containing each electrode active material, solvent, and binder, and are manufactured through a slurry coating process in which this is coated and then dried.

[0061] The electrode slurry can be coated on the current collector by distributing the electrode slurry on the current collector and then uniformly dispersing it using a doctor blade, die casting, comma coating, screen printing, etc. Alternatively, the electrode slurry can be formed on a separate substrate and then bonded to the current collector by pressing or lamination. In this case, the final coating thickness can be adjusted by adjusting the concentration of the slurry solution or the number of coatings.

[0062] The drying process is a process for removing the solvent and water from the slurry to dry the slurry coated on the metal current collector, and can vary depending on the solvent used. For example, it is performed in a vacuum oven at 50 to 200°C. Drying methods include drying with warm air, hot air, or low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. The drying time is not particularly limited, but is usually within the range of 30 seconds to 24 hours.

[0063] After the drying process, a cooling process may be further included, and the cooling process may be slow cooling to room temperature so that the recrystallization structure of the binder is well formed.

[0064] If necessary, a rolling process may be performed after the drying process to increase the capacity density of the electrode and the adhesion between the current collector and the active material by passing the electrode between two rolls heated to a high temperature and compressing it to a desired thickness. The rolling process is not particularly limited in the present invention, and any known rolling process may be used. For example, the rolling process may be performed by passing the electrode between rotating rolls or using a flat press.

[0065] The shape of the all-solid-state battery is not particularly limited, and various shapes such as a cylindrical shape, a laminated shape, and a coin shape can be used.

[0066] Below, preferred examples are presented to help understand the present invention. However, the following examples are merely illustrative of the present invention, and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical spirit of the present invention. It is of course also understood that such changes and modifications fall within the scope of the appended claims.

[0067] <Manufacturing solid electrolyte membranes for all-solid-state batteries> Example 1 98.5 wt % of argyrodite (Li6PS5Cl) was used as the solid electrolyte, and 1.5 wt % of polyphenylene sulfide was used as the linear structure additive. These were dispersed in anisole and stirred to produce a slurry for forming the solid electrolyte layer.

[0068] Polyethylene terephthalate was used as a release film, and the slurry for forming the solid electrolyte layer was coated on the release film, which was then vacuum dried at 100°C for 12 hours and rolled to produce a solid electrolyte membrane for an all-solid-state battery with a thickness of 38 μm.

[0069] Example 2 A 45 μm thick solid electrolyte membrane for an all-solid-state battery was prepared in the same manner as in Example 1, except that 97 wt % of argyrodite (Li6PS5Cl) and 3 wt % of polyphenylene sulfide were used.

[0070] Example 3 A 40 μm thick solid electrolyte membrane for an all-solid-state battery was prepared in the same manner as in Example 1, except that 95 wt % of argyrodite (Li6PS5Cl) and 5 wt % of polyphenylene sulfide were used.

[0071] Comparative Example 1 Argyrodite (Li6PS5Cl) was used alone as the solid electrolyte, and this was filled into a titanium mold to produce a 732 μm thick solid electrolyte membrane for all-solid-state batteries.

[0072] Comparative Example 2 95% by weight of argyrodite (Li6PS5Cl) was used as the solid electrolyte, and 5% by weight of polytetrafluoroethylene was used as the binder. These were dispersed in anisole and stirred to prepare a slurry for forming the solid electrolyte layer.

[0073] Polyethylene terephthalate was used as a release film, and the slurry for forming the solid electrolyte layer was coated on the release film. After vacuum drying at a temperature of 100°C for 12 hours, a 50 μm-thick solid electrolyte membrane for an all-solid-state battery was produced.

[0074] Comparative Example 3 The same procedure as in Comparative Example 1 was carried out, except that 97 wt% of argyrodite (Li6PS5Cl) and 3 wt% of polytetrafluoroethylene were used. However, due to the low binder content, the strength was low and the structure could not be maintained, resulting in breakage.

[0075] Comparative Example 4 A 49 μm thick solid electrolyte membrane for an all-solid-state battery was prepared in the same manner as in Example 1, except that a nonwoven fabric (porosity 48%, thickness 38 μm) was used instead of the linear structure additive.

[0076] Experimental Example 1: Measurement of ionic conductivity of solid electrolyte membrane for all-solid-state battery The ionic conductivities of the solid electrolyte membranes for all-solid-state batteries prepared in Examples 1 to 3 and Comparative Examples 1, 2 and 4 were measured.

[0077] The solid electrolyte membranes for all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1, 2, and 4 were interposed between SUS plates, and then the ionic resistance was measured by impedance spectroscopy at room temperature, and the ionic conductivity was calculated. The results are shown in Table 1 below.

[0078] [Table 1]

[0079] From the results in Table 1, it was confirmed that the solid electrolyte membranes of Examples 1 to 3, which contain a linear structure additive that plays a role in supporting the solid electrolyte, have excellent ionic conductivity. It was also found that the solid electrolyte membrane can maintain its structure (free-standing) even when it contains a small amount of additive, 0.5 to 5 wt %.

[0080] On the other hand, in Comparative Example 1, which used only a solid electrolyte, the thin film was broken when slurry coating was carried out to produce a thin film, making it impossible to measure ionic conductivity. When a solid electrolyte membrane of the above thickness was produced using a mold for ionic conductivity measurement, high ionic conductivity was observed. In other words, Comparative Example 1 had high ionic conductivity, but it was found that it was impossible to produce a thin film.

[0081] The solid electrolyte membrane of Comparative Example 2, in which a binder was used instead of the additive having a linear structure, had lower ionic conductivity than the solid electrolyte membrane of Example 3, in which the same amount of the additive having a linear structure was used. The solid electrolyte membrane of Comparative Example 3 had a low binder content, and the structure of the solid electrolyte membrane could not be maintained.

[0082] Comparative Example 4, which used a nonwoven fabric instead of a linear structure additive, showed lower ionic conductivity than Examples 1 to 3. This result was due to the fact that although the nonwoven fabric is connected to the linear structure, it is difficult to completely fill the pores between the fibers with solid electrolyte. In addition, the use of a nonwoven fabric can also cause problems such as limited adhesive strength between electrodes.

[0083] Therefore, it is clear that the solid electrolyte membrane for an all-solid-state battery of the present invention can be thinned and still exhibit high ionic conductivity.

Claims

1. The solid electrolyte has a particle form and an additive has a linear structure, The additive having a linear structure has an average length of 500 nm to 5 mm and an average diameter of 50 nm to 5 μm; The linear structure additive has a ratio of average length to average diameter (average length / average diameter) of 10 to 200; The solid electrolyte membrane for an all-solid-state battery, wherein the additive having a linear structure is made of at least one selected from the group consisting of polyphenylene sulfide, polyether ether ketone, and polysulfone.

2. The solid electrolyte membrane for an all-solid-state battery according to claim 1 , wherein the additive having a linear structure is in the form of polymer fibers.

3. 2. The solid electrolyte membrane for an all-solid-state battery according to claim 1, wherein the additive having a linear structure is contained in an amount of 0.5 to 5 wt % based on the total weight of the solid electrolyte membrane for an all-solid-state battery.

4. 2. The solid electrolyte membrane for an all-solid-state battery according to claim 1, wherein the solid electrolyte is a sulfide-based solid electrolyte or a polymer-based solid electrolyte.

5. 2. The solid electrolyte membrane for an all-solid-state battery according to claim 1, wherein the thickness of the solid electrolyte membrane for an all-solid-state battery is 5 to 50 μm.

6. 2. The solid electrolyte membrane for an all-solid-state battery according to claim 1, wherein the ionic conductivity of the solid electrolyte membrane for an all-solid-state battery is 0.01 to 10 mS / cm.

7. An all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte membrane interposed between the positive electrode and the negative electrode, The solid electrolyte membrane is the solid electrolyte membrane for an all-solid-state battery according to any one of claims 1 to 6.

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