Preparation method of sulfide-type solid electrolyte sheet

Abstract

The present invention relates to a preparation method of a sulfide-type solid electrolyte sheet, comprising the steps of: mixing a sulfide-type solid electrolyte and a polymer binder with a solvent so as to prepare a solid electrolyte slurry; applying the solid electrolyte slurry onto a carrier film so as to form a slurry layer; disposing a prepared sheet-shaped support on the slurry layer; rolling the slurry layer, on which the sheet-shaped support is disposed, so as to form an initial solid electrolyte sheet; and drying the initial solid electrolyte sheet, and then rolling same so as to peel off the sulfide-type solid electrolyte sheet.

Description

Method for manufacturing a sulfide-based solid electrolyte sheet

[0001] The present invention relates to a method for manufacturing a sulfide-based solid electrolyte sheet.

[0002]

[0003] Research on the safety issues and energy density of high-capacity batteries is gaining attention, and all-solid-state batteries are gaining attention as next-generation batteries. These all-solid-state batteries replace liquid electrolytes, which can cause explosions, with solid electrolytes. This eliminates the use of flammable solvents within the battery, eliminating the risk of ignition or explosion caused by reactions like the decomposition of conventional electrolytes, ensuring battery safety.

[0004] In addition, since lithium metal or a lithium alloy can be used as the negative electrode material, the energy density in relation to the mass and volume of the battery can be improved. The solid electrolyte used in the above-mentioned all-solid-state battery is generally an inorganic solid electrolyte, and various studies are being conducted on a sulfide-based solid electrolyte having a composition such as Li6PS5Cl, which has an argyrodite structure among the above-mentioned all-solid-state batteries.

[0005] In order to commercialize all-solid-state batteries, large-area batteries must be manufactured. To manufacture large-area all-solid-state batteries, sheeting of the positive electrode, separator, and negative electrode, like in existing lithium-ion batteries, is essential.

[0006] In particular, the solid electrolyte layer must be manufactured in the form of a membrane to be used as a separator. However, due to the characteristics of ceramic materials, their elasticity and supporting strength are insufficient, making large-area mass production difficult. In addition, the brittle nature of the solid-state battery cell causes cracks to occur, resulting in a high cell failure rate. To reduce this cracking rate, if the membrane is manufactured in the form of a thick film, the ionic conductivity decreases, lowering the energy density of the solid-state battery cell.

[0007] For separators, a roll-to-roll process is required for large-scale production, and suitable tensile strength of the solid electrolyte membrane is essential for easy cell assembly. Furthermore, thin solid electrolyte membranes are essential for achieving high cell energy density in all-solid-state batteries.

[0008] Conventional methods for manufacturing large-area solid electrolyte membranes involve applying a solid electrolyte solution slurry onto a substrate, coating and drying it via casting, and then peeling it from the substrate to create a self-supporting membrane. This method not only hampers the mechanical rigidity of the solid electrolyte membrane, making it difficult to apply to roll-to-roll processes for mass production, but also makes handling the solid electrolyte membranes used for all-solid-state battery cell assembly challenging.

[0009] Meanwhile, the existing method of manufacturing a solid electrolyte membrane using a porous support is a method of placing a porous support on a substrate and casting a slurry, so it is difficult to manufacture it in the form of a thin film, and it may not be suitable for a roll-to-roll process due to the substrate and porous support not being bonded.

[0010] When a solid electrolyte membrane containing a solid electrolyte is made into a thin film, there is a problem of reduced mechanical strength, and in addition, since the solid electrolyte membrane acts as an ion channel between the anode and cathode, high ion conductivity is required.

[0011] Therefore, there is a need to develop a manufacturing process technology that can mass-produce sulfide-based solid electrolyte sheets with excellent strength and ionic conductivity while simultaneously controlling resistance increase.

[0012]

[0013] One object of the present invention is to provide a manufacturing method capable of mass-producing a sulfide-based solid electrolyte sheet having high ionic conductivity and mechanical strength while having a controlled thickness.

[0014]

[0015] This application claims priority to Republic of Korea Patent Application No. 10-2024-0080529, filed June 20, 2024, the entire contents of which are incorporated herein by reference.

[0016] A method for manufacturing a sulfide-based solid electrolyte sheet according to the present invention comprises the steps of: preparing a solid electrolyte slurry by mixing a sulfide-based solid electrolyte and a polymer binder with a solvent; applying the solid electrolyte slurry onto a carrier film to form a slurry layer; disposing a prepared sheet-shaped support on the slurry layer; rolling the slurry layer on which the sheet-shaped support is disposed to form an initial solid electrolyte sheet; and drying the initial solid electrolyte sheet and then rolling it to peel off the sulfide-based solid electrolyte sheet.

[0017] In the step of forming a slurry layer by applying the above solid electrolyte slurry onto a carrier film, the thickness of the slurry layer may be greater than 150 μm and less than 650 μm.

[0018] In the step of forming a slurry layer by applying the above solid electrolyte slurry onto a carrier film, the thickness of the sheet-shaped support may be 5 to 40 μm.

[0019] In the step of preparing a solid electrolyte slurry by mixing the above sulfide-based solid electrolyte and polymer binder with a solvent, the solid content in the solid electrolyte slurry may be 30 to 60 wt%.

[0020] In the step of preparing a solid electrolyte slurry by mixing the above sulfide-based solid electrolyte and polymer binder with a solvent, the sulfide-based solid electrolyte and the polymer binder can be mixed in a weight ratio (sulfide-based solid electrolyte: polymer binder) of 90:10 to 99:1.

[0021] In the step of drying the above-mentioned initial solid electrolyte sheet and then rolling it to obtain a sulfide-based solid electrolyte sheet, the initial solid electrolyte sheet can be dried at a temperature in the range of 40 to 100°C.

[0022] The step of forming an initial solid electrolyte sheet by rolling the slurry layer on which the sheet-shaped support is arranged is performed by rolling the slurry layer on which the sheet-shaped support is arranged while passing it between two rollers positioned horizontally in parallel, and the gap between the two rollers may be in the range of 20 to 100 um.

[0023] The step of drying the initial solid electrolyte sheet and then rolling it to peel off the sulfide-based solid electrolyte sheet includes rolling the dried initial solid electrolyte sheet while passing it between two rollers positioned horizontally in parallel, and the gap between the two rollers may be in the range of 30 to 70 um.

[0024] The above sulfide-based solid electrolyte may be a material represented by the following chemical formula 1.

[0025] [Chemical Formula 1]

[0026] Li x1 P y1 S z1 D w1 M1 a1

[0027] In the above chemical formula 1, D is at least one selected from among F, Cl, Br, and I, M1 is at least one selected from among B, Al, Si, Ga, Ge, In, Sn, O, N, As, Se, Sb, and Te, and 4≤x1≤8, 0.5≤y1≤1.5, 3≤z1≤7, 0≤a1≤2.

[0028] The above sheet-shaped support may be one or more polymers selected from PE, PP, PET, and PI.

[0029] In another embodiment of the present invention, a sulfide-based solid electrolyte sheet manufactured according to the method for manufacturing the sulfide-based solid electrolyte sheet is provided.

[0030] In another embodiment of the present invention, an all-solid-state battery comprising the sulfide-based solid electrolyte sheet is provided.

[0031]

[0032] A method for manufacturing a sulfide-based solid electrolyte sheet according to one embodiment of the present invention has the advantage of being able to efficiently mass-produce a sulfide-based solid electrolyte sheet having excellent ionic conductivity and mechanical strength while having a controlled thickness.

[0033]

[0034] Figure 1 briefly illustrates a manufacturing process flow of a solid electrolyte sheet according to one embodiment of the present invention.

[0035] Figure 2 is a cross-sectional SEM analysis image of a solid electrolyte sheet manufactured according to Manufacturing Example 1.

[0036] Figure 3 is a photograph of a solid electrolyte sheet manufactured according to Manufacturing Example 4.

[0037] Figure 4 is a photograph of a solid electrolyte sheet manufactured according to Comparative Manufacturing Example 4.

[0038] Figure 5 is a graph showing the results of an electrochemical stability evaluation of a solid electrolyte sheet manufactured according to Manufacturing Example 4.

[0039]

[0040] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0042] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0043] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0044] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0045] In this specification, the term "combination(s) thereof" described in the expression in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expression in the Makushi format, and means including any one or more selected from the group consisting of said components.

[0046] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0047]

[0048] 1. Method for manufacturing solid electrolyte sheets

[0049] According to another embodiment of the present invention, a method for manufacturing a solid electrolyte sheet may include the steps of: preparing a solid electrolyte slurry by mixing a sulfide-based solid electrolyte and a polymer binder with a solvent; applying the solid electrolyte slurry onto a carrier film to form a slurry layer; placing a prepared sheet-shaped support on the applied slurry layer; rolling the slurry layer on which the sheet-shaped support is placed to form an initial solid electrolyte sheet; and drying and then rolling the initial solid electrolyte sheet to obtain a sulfide-based solid electrolyte sheet.

[0050]

[0051] Hereinafter, a method for manufacturing a solid electrolyte sheet according to the present invention will be described.

[0052]

[0053] First, a step of preparing a solid electrolyte slurry by mixing a sulfide-based solid electrolyte and a polymer binder with a solvent is performed.

[0054] The above solid electrolyte may be a sulfide-based solid electrolyte, and may further include an oxide-based, polymer-based, or halide-based solid electrolyte, but is not limited thereto.

[0055] The above sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (wherein m, n are positive numbers, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers, and M is one of P, Si, Ge, B, Al, Ga In), Li3PS4, Li7P3S 11 , Li 7-x PS 6-x Cl x (However, 0≤x≤2), Li 7-x PS 6-x Br x (where 0≤x≤2), and Li 7-x PS 6-x I x (However, there can be one or more selected from 0≤x≤2).

[0056] The above sulfide-based solid electrolyte is manufactured by treating starting materials such as Li2S and P2S5 by a melting rapid cooling method or a mechanical milling method. In addition, a heat treatment may be performed after the treatment. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may be, for example, one of the above-described sulfide-based solid electrolyte materials that contains at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements. For example, the solid electrolyte may be a material containing Li2S-P2S5.

[0057] From the perspective of more desirable implementation of ionic conductivity, the sulfide-based solid electrolyte may have an argyrodite-based crystal structure.

[0058] A sulfide-based solid electrolyte having an argyrodite crystal structure may contain, for example, Li, P, S, and halogen elements, and may further contain other doping elements as needed. By further including other doping elements in the argyrodite crystal structure, the moisture stability of the solid electrolyte may be improved, or the electrochemical properties, such as the capacity of the battery, may be more preferably realized.

[0059] For example, the sulfide-based solid electrolyte may be a material represented by the following chemical formula 1.

[0060] [Chemical Formula 1]

[0061] Li x1 P y1 S z1 D w1 M a1

[0062] In the above chemical formula 1, D is at least one selected from among F, Cl, Br, and I, M is at least one selected from among B, Al, Si, Ga, Ge, In, Sn, O, N, As, Se, Sb, and Te, and 4≤x1≤8, 0.5≤y1≤1.5, 3≤z1≤7, 0≤a1≤2.

[0063]

[0064] The above polymer binder may include a repeating unit including one or more polar functional groups selected from a nitrile group (-CN), an ester group (-C(=O)O-), and an acetate group (-OC(=O)-), and specifically may include one or more selected from polymers of the NBR, HNBR, and Acrylate series.

[0065] In the present invention, it is preferable to use the polymer binder described above to form a chemically stable bond with the sulfide solid electrolyte.

[0066] The above sulfide-based solid electrolyte and polymer binder can be mixed at a weight ratio (sulfide-based solid electrolyte:polymer binder) of 80:20 or more, and specifically, can be mixed in a range of 80:20 to 99.5:0.5, 85:15 to 99:1, or 90:10 to 99:1.

[0067] The above sulfide-based solid electrolyte and polymer binder can be mixed with a solvent and then stirred using a stirring member at a stirring speed of 500 to 5000 rpm for 1 minute to 1 hour to prepare a solid electrolyte slurry. The stirring speed can be specifically 1000 to 3000 rpm or 1500 to 2500 rpm.

[0068] The solid content in the above solid electrolyte slurry may be 20 wt% or more, and specifically 25 to 70 wt%, 30 to 60 wt%, or 40 to 50 wt%.

[0069] The above solids content means the total weight percentage of solid matter excluding solvent based on the total weight of the slurry.

[0070] The solvent may be, for example, xylene, toluene, isobutyl isobutyrate, or a combination thereof, but is not necessarily limited thereto, and any solvent used in the art may be used.

[0071] The above solid electrolyte composition may further include a dispersant that can improve the dispersibility of the solid content in the solid electrolyte composition, and may further include other additives as needed.

[0072]

[0073] Next, a step of applying the solid electrolyte slurry onto a carrier film to form a slurry layer is performed.

[0074] The thickness of the above slurry layer may be greater than 150 µm and less than 650 µm, and specifically may be 200 to 600 µm, 300 to 500 µm, or 350 to 450 µm.

[0075] In the present invention, the thickness of the slurry layer can be adjusted to control the amount of solid electrolyte slurry impregnated into the porous support in the form of a sheet described later.

[0076] When the thickness of the slurry layer is within the above range, it is preferable because there is an advantage in that a solid electrolyte sheet of excellent quality can be manufactured by uniformly disposing a support in the form of a sheet as described below on the slurry layer.

[0077] If the thickness of the slurry layer is thinner than the above range, there is a problem that the solid electrolyte is difficult to impregnate into the porous support, and if the thickness of the slurry layer is thicker than the above range, the support cannot support it, so there is a problem that the slurry remaining in excess on the surface of the support causes cracks to occur after drying.

[0078] In the present invention, slurry application may utilize a blade bar head, but the method of applying the slurry is not particularly limited as long as the desired slurry layer can be formed.

[0079] The carrier film may be a hydrophobic film having at least one wide surface coated with Mylar film, PET, PTFE, etc.

[0080] Meanwhile, the support impregnated with the solid electrolyte slurry is placed on the hydrophobic surface of the carrier film.

[0081] In this way, by imparting hydrophobicity to the surface of the carrier film facing the support impregnated with the solid electrolyte slurry, there is an advantage in that the solid electrolyte slurry impregnated in the support can be prevented from escaping from the pores of the support.

[0082]

[0083] Next, a step of placing a prepared sheet-shaped support on the slurry layer is performed.

[0084] The above sheet-shaped support may be a non-woven fabric, a glass fiber fabric, or a combination thereof.

[0085] The thickness of the above sheet-shaped support may be 5 to 40 μm, is made of polymer or glass fiber, and has the characteristic of having breathability.

[0086] When the thickness of the above sheet-shaped support is within the above range, it is possible to manufacture a thin solid electrolyte membrane capable of increasing cell energy density, and there is an advantage in that solid electrolytes can be uniformly and comprehensively impregnated, and a self-supporting solid electrolyte sheet of excellent quality can be manufactured.

[0087] In addition, the nonwoven fabric may include one or more polymer resins selected from among polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyvinylidene fluoride (PVDF), and Teflon (PTFE), but is not limited thereto.

[0088] The nonwoven fabric may be a porous support including pores having a diameter of 0.5 to 2.0 μm, specifically 1.0 to 2.0 μm, and the basis weight of the nonwoven fabric may be 10 to 20 g / m 2 , specifically 12 to 18 g / m 2 The support of the nonwoven fabric may have a thickness of 50 μm or less, specifically 5 to 40 μm, and the air permeability of the nonwoven fabric may be 400 to 700 cm 3 / cm 2 / s, specifically 500 to 600 cm 3 / cm 2 / s may be.

[0089] In addition, the glass fiber fabric may include one or more polymer resins selected from SiO2, Al2O3, CaO, and MgO, but is not limited thereto.

[0090] The present invention utilizes the sheet-shaped porous support, thereby providing mechanical rigidity for the roll-to-roll process required for large-area production. Furthermore, the application of the porous support provides self-supporting properties to the solid electrolyte sheet, facilitating the manufacturing process when manufacturing large-area all-solid-state batteries.

[0091]

[0092] Next, a step of rolling the slurry layer on which the sheet-shaped support is placed is performed to form an initial solid electrolyte sheet.

[0093] Specifically, the solid electrolyte slurry applied on the carrier film can be impregnated into the porous support through rolling to impregnate the porous support to the inside.

[0094] In the present invention, the slurry layer on which the sheet-shaped support is arranged can be rolled by passing it between two rollers positioned horizontally in parallel.

[0095] In the present invention, the gap between the two rollers may be 0 to 300 um, specifically 15 to 250 um, or 20 to 100 um.

[0096] The rolling thickness, i.e. the gap, was set to be greater than the combined thickness of the minimum support and carrier film.

[0097] When rolling is performed with a rolling thickness gap within the above range, there is an advantage in that the solid electrolyte powder and binder are impregnated from the surface of the support to the opposite end, and when it is less than the lower limit of the above range, there is a problem in that the impregnation is insufficient to the inside of the support, so that pores exist inside, thereby reducing ionic conductivity, and when it exceeds the upper limit of the above range, excessive rolling causes the support to tear, which causes a problem in membrane uniformity.

[0098] At this time, the rolling pressure may be 2 to 20 MPa, specifically 5 to 10 MPa, 6 to 9 MPa.

[0099] When rolling in the above pressure range, it is preferable that the sheet-shaped support be prevented from being deformed or broken, and the solid electrolyte sheet desired in the present invention can be manufactured.

[0100]

[0101] Next, a step of drying the initial solid electrolyte sheet and then rolling it to obtain a sulfide-based solid electrolyte sheet is performed.

[0102] The step of drying the initial solid electrolyte sheet can be performed at a temperature of 100°C or lower for the purpose of removing the solvent within the initial solid electrolyte sheet, and specifically, can be performed at a temperature in the range of 40°C to 100°C, or a temperature in the range of 40°C to 60°C.

[0103] The above drying can be performed for 30 minutes or more, and specifically for 1 to 6 hours.

[0104] When drying is performed within the above temperature range and time range, it is preferable to manufacture a solid electrolyte sheet of excellent quality.

[0105]

[0106] After the above drying is completed, a step of rolling the dried initial solid electrolyte sheet to peel off the solid electrolyte sheet is performed.

[0107] In the present invention, the dried initial solid electrolyte sheet can be rolled by passing it between two rollers positioned horizontally and parallel.

[0108] In the present invention, the gap between the two rollers through which the dried initial solid electrolyte sheet passes may be in the range of 10 to 100 um, specifically 20 to 90 um, 30 to 70 um, or 40 to 60 um.

[0109] The above rolling can be performed by applying pressure in the range of 10 to 100 MPa, and specifically, can be performed by applying pressure in the range of 20 to 90 MPa, 30 to 70 MPa, or 30 to 50 MPa.

[0110] Rolling can improve the membrane tensile strength by binding the solid electrolytes and binder to the support.

[0111] The above rolling can facilitate the densification of the solid electrolytes within the porous support, facilitating their separation from the carrier film. Furthermore, the densification between the solid electrolyte powders increases the interparticle contact area, thereby forming numerous lithium ion migration paths, thereby enhancing ionic conductivity.

[0112]

[0113] 2. Solid electrolyte sheet

[0114] A sulfide-based solid electrolyte sheet manufactured according to the above solid electrolyte manufacturing method includes a sulfide-based solid electrolyte; a polymer binder; and a sheet-shaped support.

[0115]

[0116] The solid electrolyte, polymer binder, and sheet-shaped support have been described in detail above, so they are omitted here.

[0117]

[0118] The solid electrolyte sheet according to one embodiment of the present invention may have a thickness in the range of 20 µm to 500 µm, specifically 20 µm to 100 µm, 30 µm to 70 µm.

[0119] The ionic conductivity of the solid electrolyte sheet according to one embodiment of the invention may be 0.40 mS / cm or more, and specifically, 0.40 to 1.5 mS / cm, 0.40 to 1.20 mS / cm.

[0120] The tensile strength of the solid electrolyte sheet according to one embodiment of the invention may be 3.0 MPa or more, and specifically may be in the range of 4.0 to 7.0 MPa.

[0121]

[0122] 3. All-solid-state battery

[0123] Another embodiment of the present invention provides an all-solid-state battery comprising: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer positioned between the positive electrode layer and the negative electrode layer, the solid electrolyte layer including the aforementioned solid electrolyte sheet.

[0124] More specifically, the above positive electrode layer may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.

[0125] The above-described positive electrode active material layer may include, for example, a positive electrode active material and a solid electrolyte. The solid electrolyte included in the positive electrode active material layer may be the same as or different from the solid electrolyte included in the solid electrolyte sheet.

[0126] A cathode active material is a material that can reversibly absorb and desorb lithium ions. Examples of cathode active materials include, but are not limited to, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate; nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide; and the like. Any material used as a cathode active material in the relevant technical field may be used. The cathode active materials may be singly or in a mixture of two or more.

[0127] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2 (in the above formula, 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α F α(In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α F2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2 (in the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoGb O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f)Fe2(PO4)3(0 ≤ f ≤ 2); A compound represented by any one of the chemical formulas of LiFePO4. In this compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. It is also possible to use a compound having a coating layer added to the surface of this compound, and it is also possible to use a mixture of the above-mentioned compound and the compound having a coating layer added. The coating layer added to the surface of these compounds includes a coating element compound of, for example, an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method includes, for example, spray coating and dipping. Since the specific coating method is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0128] The positive electrode active material layer may include, for example, a solid electrolyte. The solid electrolyte included in the positive electrode layer may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0129] The positive electrode active material layer may include, for example, a binder. The binder may include, but is not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like, and any binder used in the art may be used.

[0130] The positive electrode active material layer may include, for example, a conductive material. The conductive material may include, but is not limited to, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc., and any conductive material used in the relevant technical field may be used.

[0131] The positive electrode active material layer may further include, for example, additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the above-described positive electrode active material, solid electrolyte, binder, and conductive agent.

[0132] As fillers, coating agents, dispersants, ion conductive aids, etc. that the positive electrode active material layer may include, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0133] The positive electrode collector may be, for example, a plate or foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The thickness of the positive electrode collector may be, for example, 1 um to 100 um, 1 um to 50 um, 5 um to 25 um, or 10 um to 20 um.

[0134]

[0135] The above negative electrode layer may more specifically include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.

[0136] The above negative electrode active material layer may include, for example, a negative electrode active material and a binder.

[0137] The above negative electrode active material may include, for example, a carbon-based negative electrode active material, a metal / metalloid negative electrode active material, or a combination thereof.

[0138] The above carbon-based negative electrode active material may be amorphous carbon. The amorphous carbon may include, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., and any material classified as amorphous carbon in the relevant technical field may be used. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0139] The metal / metalloid negative electrode active material includes at least one selected from the group consisting of lithium (Li), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto, and any metal negative electrode active material or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used.

[0140] The binder included in the negative electrode active material layer may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited thereto, and any binder used in the relevant technical field may be used. The binder may be composed of a single binder or a plurality of different binders.

[0141] By including a binder in the negative electrode active material layer, the negative electrode active material layer is stabilized on the negative electrode current collector. Furthermore, cracking of the negative electrode active material layer is suppressed despite changes in volume and / or relative position of the negative electrode active material layer during the charge / discharge process.

[0142] The negative active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, coating agents, dispersants, and ion conductive aids.

[0143] The all-solid-state battery may further include a second negative electrode active material layer disposed between the negative electrode current collector and the negative electrode active material layer during charging. The second negative electrode active material layer may be deposited between the negative electrode current collector and the negative electrode current collector during the charging process, or may be further disposed on the negative electrode active material layer during electrode assembly. The second negative electrode active material layer may be a metal layer containing lithium or a lithium alloy. The lithium alloy includes, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, and the like, and any lithium alloy used in the art may be used. The second negative electrode active material layer may be made of one of these alloys and / or lithium, or may be made of multiple types of alloys and / or lithium.

[0144] The negative electrode current collector may be composed of, for example, a material that does not react with lithium, i.e., does not form an alloy or compound. The negative electrode current collector may include, but is not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material that is used as an electrode current collector in the art may be used. The negative electrode current collector may be composed of one of the above-described metals, or may be composed of an alloy or a coating material of two or more metals. The negative electrode current collector may be, for example, in the form of a plate or foil.

[0145]

[0146] Hereinafter, embodiments of the present invention will be described in more detail through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0147]

[0148] <Manufacturing Example>

[0149] (Preparation of binder solution)

[0150] A binder solution was obtained by mixing isobutyl isobutyrate, an organic solvent, and nitrile butadiene rubber (NBR), a binder, in a mass ratio of 90:10.

[0151]

[0152] (Slurry manufacturing)

[0153] Li6PS5Cl was added to the binder solution prepared above and mixed to prepare a slurry. The weight ratio of the solid electrolyte Li6PS5Cl and the binder (NBR) (Li6PS5Cl: NBR) was 98:2.

[0154] At this time, the solid content in the slurry was 30 wt%.

[0155] Here, the above solid content was calculated by the following equation.

[0156] Solid content (wt%) = (binder weight + solid electrolyte weight) / (binder weight + solid electrolyte weight + solvent weight) * 100%

[0157]

[0158] (Applied on carrier film)

[0159] The above-mentioned slurry was applied onto a carrier film, and the slurry layer thickness was adjusted using a blade bar head. Slurry layers were formed at thicknesses of 200 um (Manufacturing Example 1), 300 um (Manufacturing Example 2), 400 um (Manufacturing Example 3), 500 um (Manufacturing Example 4), and 600 um (Manufacturing Example 5).

[0160] The amount impregnated into the porous support is controlled depending on the thickness of the applied slurry, and thus the thickness of the final solid electrolyte membrane can be controlled.

[0161]

[0162] (Porous support bonding)

[0163] A porous support was placed on the solid electrolyte slurry cast on the carrier film manufactured above, thereby forming a slurry layer on which the support was placed.

[0164] Here, a porous support made of polypropylene and having a thickness of 30 μm was used.

[0165]

[0166] (rolling)

[0167] In order to impregnate the solid electrolyte slurry applied on the carrier film into the porous support, the slurry layer on which the support was placed was rolled while passing between two rollers positioned horizontally in parallel.

[0168] At this time, the gap between the two rollers was fixed to 200 μm, and the rolling was performed to form an initial solid electrolyte sheet.

[0169] Additionally, the pressure during rolling is 50 MPa.

[0170]

[0171] (dry)

[0172] The above initial solid electrolyte sheet was dried in a vacuum atmosphere at 50 degrees for 1 hour.

[0173]

[0174] (Peel)

[0175] The above dried initial solid electrolyte sheet was rolled by passing it between two rollers positioned horizontally parallel with a gap of 50 μm at 30 MPa, thereby peeling off the solid electrolyte sheet.

[0176] Figure 2 shows a photograph of a solid electrolyte sheet manufactured according to Manufacturing Example 4.

[0177]

[0178] <Comparative Manufacturing Example 1>

[0179] (Preparation of binder solution)

[0180] A binder solution was obtained by mixing isobutyl isobutyrate, an organic solvent, and nitrile butadiene rubber (NBR), a binder, in a mass ratio of 90:10.

[0181]

[0182] (Slurry manufacturing)

[0183] Li6PS5Cl and the porous support used in Preparation Example 1 were added to the binder solution prepared above and mixed to prepare a slurry. The weight ratio of the solid electrolyte Li6PS5Cl and the binder (NBR) (Li6PS5Cl: NBR) was 98:2.

[0184] At this time, the solid content in the slurry was 30 wt%.

[0185] Here, the above solid content was calculated by the following equation.

[0186] Solid content (wt%) = (binder weight + solid electrolyte weight) / (binder weight + solid electrolyte weight + solvent weight) * 100%

[0187]

[0188] (Integrated with carrier film)

[0189] The above slurry was applied onto a PET carrier film.

[0190] At this time, the thickness of the coating layer formed on the carrier film is 50 μm.

[0191]

[0192] (dry)

[0193] The carrier film coated with the above slurry was dried at 50°C for 1 hour to obtain a carrier film having a solid electrolyte sheet layer formed thereon.

[0194]

[0195] (Peel)

[0196] The carrier film on which the above-mentioned dried solid electrolyte sheet layer was formed was rolled at a pressure of 30 MPa to peel off the solid electrolyte sheet.

[0197]

[0198]

[0199] <Comparative Manufacturing Example 2>

[0200] A solid electrolyte sheet was manufactured in the same manner as in Manufacturing Example 1, except that the slurry manufactured above was applied onto a carrier film to form a slurry layer with a thickness of 100 μm, dried in a dryer at a temperature of 70°C for 1 hour under atmospheric pressure conditions, and then a porous support was bonded.

[0201]

[0202] <Comparative Manufacturing Examples 3 and 4>

[0203] A solid electrolyte sheet was manufactured using the same method as Manufacturing Example 1, except that the thickness of the slurry layer formed by applying the above-mentioned manufactured slurry onto a carrier film was formed as shown in Table 1 below.

[0204]

[0205] FIG. 3 is a photograph of a solid electrolyte sheet manufactured according to Manufacturing Example 4, and FIG. 4 is a photograph of a solid electrolyte sheet manufactured according to Comparative Manufacturing Example 4.

[0206] Referring to Fig. 3, when the slurry layer thickness was 500 μm, an electrolyte sheet of excellent quality was finally manufactured.

[0207] On the other hand, referring to Fig. 5, when the slurry layer thickness is 650 μm, it can be confirmed that the final manufactured electrolyte sheet is cracked. This is believed to be due to the cracks occurring after drying of the slurry remaining in excess on the support surface.

[0208]

[0209]

[0210] <Evaluation Example 1: SEM Image Analysis>

[0211] SEM image analysis was performed on the surface of the solid electrolyte sheet manufactured according to Manufacturing Example 1, and the results are shown in Fig. 1.

[0212] SEM image analysis was performed using a common method used in the field of solid-state batteries, so a detailed description is omitted.

[0213] Referring to Figures 1 and 2, it can be seen that the solid electrolytes are uniformly distributed, and the cross-section shows that the solid electrolyte powders are impregnated with the porous support at the center. From this, it is believed that the solid electrolytes are in close contact, securing a movement path for lithium ions and achieving high ionic conductivity.

[0214]

[0215] <Evaluation Example 2: Tensile Strength>

[0216] The tensile strength of the solid electrolyte sheets manufactured according to Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 4 was evaluated using a UTM tensile tester (Ultimate Tensile strength).

[0217] Specifically, the upper and lower parts of a solid electrolyte sheet sample (5 cm in length X 5 cm in width) are fixed, and the sample is pulled in tension to measure the stress at which the sample breaks.

[0218]

[0219] <Evaluation Example 3: Lithium-ion Conductivity>

[0220] The solid electrolyte sheets manufactured according to Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 4 were used as working electrodes to fasten the cells at a pressure of 70 MPa using SUS, and then a voltage of 10 mV was applied at 30°C to measure the impedance.

[0221] Table 1 below shows the evaluation results of solid electrolyte sheets manufactured according to Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 4.

[0222]

[0223]

[0224] Referring to Table 1 above, when the slurry layer thickness is 400 μm or more, the carrier film / non-woven fabric is sufficiently impregnated through rolling after attaching the porous support, and the remaining excess slurry is removed (squeegeed out) from the rolling roll, so it can be confirmed that even if the slurry casting thickness is increased, the ionic conductivity, tensile strength, and thickness do not increase significantly.

[0225] Meanwhile, in the case of comparative manufacturing example 4 in which the slurry layer thickness increased to 650 μm, it can be confirmed that the ionic conductivity and tensile strength decreased compared to manufacturing example 5.

[0226]

[0227] <Evaluation Example 4: Electrochemical Stability Evaluation Analysis>

[0228] Electrochemical stability evaluation (cyclic voltammetry) was conducted on the manufactured solid electrolyte sheet.

[0229] To evaluate the electrochemical stability of the manufactured solid electrolyte sheet, stainless steel was used as the working electrode and lithium metal was used as the counter electrode. The current scan rate was 1 mV / s, and the voltage range was set to 0 V to 5 V.

[0230] The results of the electrochemical stability evaluation of the solid electrolyte sheet manufactured according to Manufacturing Example 4 are shown in Fig. 5.

[0231] Referring to Fig. 5, the fabricated solid electrolyte membrane did not exhibit any side reaction peaks within the cell potential range of 0 to 5 V. This indicates that the carrier film, nonwoven fabric, solvent, binder, etc. used during the manufacturing process did not induce any separate oxidation / reduction reactions within the potential range. This suggests that the solid electrolyte was not affected during the solid electrolyte membrane manufacturing process.

[0232]

[0233] <Evaluation Example 5: All-solid-state battery performance evaluation>

[0234] After manufacturing the all-solid-state battery, it was aged at room temperature for 2 hours and then subjected to initial cycling. Capacity evaluation was performed using 180 mAh / g as the reference capacity, and charge / discharge conditions were applied at CC / CV 2.5 to 4.20 V with a 1 / 20 C cut-off. One cycle was performed under 0.1 C charge / 0.1 C discharge conditions.

[0235] Additionally, the internal resistance of the battery was evaluated by measuring the impedance while the all-solid-state battery was charged to the upper limit voltage of 4.20 V.

[0236] The results of the all-solid-state battery performance evaluation are shown in Table 2 below.

[0237]

[0238]

[0239] Referring to Table 2 above, the charge capacity of the all-solid-state batteries manufactured according to Manufacturing Examples 1 to 5 was found to be 202 mAh / g or more, the discharge capacity was found to be 178 mAh / g or more, and the resistance was found to be 52Ω or less. In addition, in the case of Manufacturing Examples 3 and 4, the discharge capacity was found to exceed 185 mAh / g, and the resistance was found to be less than 40Ω.

[0240] On the other hand, the charge capacity of the all-solid-state battery manufactured according to Comparative Manufacturing Examples 1 to 3 was found to be less than 200 mAh / g, the discharge capacity was found to be less than 154 mAh / g, and the resistance was found to be 120 Ω or more.

[0241] In the case of Comparative Manufacturing Example 1, the solid electrolyte was not impregnated at all within the porous support, so lithium ions could not conduct and thus did not contribute to the discharge capacity.

[0242]

[0243] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

[0244] Accordingly, the actual scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A step of preparing a solid electrolyte slurry by mixing a sulfide-based solid electrolyte and a polymer binder with a solvent; A step of forming a slurry layer by applying the solid electrolyte slurry onto a carrier film; A step of placing a prepared sheet-shaped support on top of the slurry layer; A step of forming an initial solid electrolyte sheet by rolling a slurry layer on which a sheet-shaped support is arranged; and A step of drying the initial solid electrolyte sheet and then rolling it to peel off the sulfide-based solid electrolyte sheet; Method for manufacturing a sulfide-based solid electrolyte sheet.

2. In paragraph 1, In the step of forming a slurry layer by applying the above solid electrolyte slurry onto a carrier film, The thickness of the above slurry layer is greater than 150㎛ and less than 650㎛, Method for manufacturing a sulfide-based solid electrolyte sheet.

3. In paragraph 1, In the step of forming a slurry layer by applying the above solid electrolyte slurry onto a carrier film, The thickness of the above sheet-shaped support is 5 to 40 μm. Method for manufacturing a sulfide-based solid electrolyte sheet.

4. In paragraph 1, In the step of preparing a solid electrolyte slurry by mixing the above sulfide-based solid electrolyte and polymer binder with a solvent, The solid content in the above solid electrolyte slurry is 30 to 60 wt%, Method for manufacturing a sulfide-based solid electrolyte sheet.

5. In paragraph 1, In the step of preparing a solid electrolyte slurry by mixing the above sulfide-based solid electrolyte and polymer binder with a solvent, The above sulfide-based solid electrolyte and polymer binder are mixed in a weight ratio (sulfide-based solid electrolyte: polymer binder) of 90:10 to 99:

1. Method for manufacturing a sulfide-based solid electrolyte sheet.

6. In paragraph 1, In the step of drying the above initial solid electrolyte sheet and then rolling it to obtain a sulfide-based solid electrolyte sheet, Drying the above initial solid electrolyte sheet at a temperature in the range of 40 to 100°C, Method for manufacturing a sulfide-based solid electrolyte sheet.

7. In paragraph 1, The step of forming an initial solid electrolyte sheet by rolling a slurry layer on which the above sheet-shaped support is arranged is as follows: Rolling the slurry layer on which the above sheet-shaped support is placed by passing it between two rollers positioned horizontally in parallel, The gap between the two rollers is in the range of 20 to 100um, Method for manufacturing a sulfide-based solid electrolyte sheet.

8. In paragraph 1, The step of drying the above initial solid electrolyte sheet and then rolling it to peel off the sulfide-based solid electrolyte sheet is: Rolling the above dried initial solid electrolyte sheet by passing it between two rollers positioned horizontally parallel, The gap between the two rollers is in the range of 30 to 70um, Method for manufacturing a sulfide-based solid electrolyte sheet.

9. In paragraph 1, The above sulfide-based solid electrolyte is a material represented by the following chemical formula 1: Method for manufacturing a sulfide-based solid electrolyte sheet. [Chemical Formula 1] Li x1 P y1 S z1 D w1 M1 a1 (In the above chemical formula 1, D is at least one selected from among F, Cl, Br, and I, M1 is at least one selected from among B, Al, Si, Ga, Ge, In, Sn, O, N, As, Se, Sb, and Te, and 4≤x1≤8, 0.5≤y1≤1.5, 3≤z1≤7, 0≤a1≤2.) 10. In paragraph 1, The above sheet-shaped support is made of one or more polymers selected from PE, PP, PET, and PI. Method for manufacturing a sulfide-based solid electrolyte sheet.

11. Manufactured according to the method for manufacturing a sulfide-based solid electrolyte sheet according to Article 1. Sulfide-based solid electrolyte sheet.

12. A solid electrolyte sheet comprising a sulfide-based electrolyte sheet according to Article 11. All-solid-state battery.

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