All-solid-state battery and method for manufacturing same

Abstract

The present invention is designed to reduce a residual solvent of an all-solid-state battery to 2500 ppm or less, and comprises the steps of: after accommodating an all-solid-state battery in a storage portion of a battery case, sealing three sides of the battery case that are adjacent to the all-solid-state battery to form a first sealing portion while forming an opening on the remaining one side; drying the all-solid-state battery at a high temperature under a vacuum condition through the opening; forming, at the opening, a cutting line along the edge of the all-solid-state battery so as to be adjacent to the all-solid-state battery; sealing, under a vacuum condition, an outer circumferential surface between the cutting line and the all-solid-state battery to form a second sealing portion; and cutting along the cutting line to remove a surplus portion.

Description

All-solid-state battery and method for manufacturing the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0094187, filed July 17, 2024, and Korean Patent Application No. 10-2025-0095778, filed July 16, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an all-solid-state battery and a method for manufacturing the same.

[0003]

[0004] A secondary battery is a device that converts external electrical energy into chemical energy, stores it, and then generates electricity when needed. They are also called rechargeable batteries, as they can be recharged multiple times. Common secondary batteries include lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium secondary batteries. Compared to disposable primary batteries, secondary batteries offer both economic and environmental benefits.

[0005] Meanwhile, with the gradual advancement of wireless communication technology, demand for lighter, thinner, and smaller portable devices and automotive components is increasing, leading to a growing demand for secondary batteries as the energy source for these devices. In particular, with the commercialization of hybrid and electric vehicles to prevent environmental pollution, research is focusing on using secondary batteries in next-generation automotive batteries to reduce manufacturing costs and weight while extending their lifespan. Among various secondary batteries, lithium secondary batteries have recently been attracting attention due to their lightweight nature, high energy density, high operating potential, and long cycle life.

[0006] In general, lithium secondary batteries are manufactured by mounting an electrode stack composed of a negative electrode, a positive electrode, and a separator inside a battery case made of a cylindrical or square metal can or an aluminum laminate sheet, and injecting an electrolyte into the electrode stack.

[0007] Conventionally, liquid electrolytes, consisting of lithium salts dissolved in non-aqueous organic solvents, have been primarily used for lithium secondary batteries. However, these liquid electrolytes not only present a high risk of electrode material degradation and organic solvent volatilization, but also pose a risk of combustion or explosion due to increased ambient and battery temperature, as well as the risk of leakage. This complicates the implementation of various safe lithium secondary batteries.

[0008] Meanwhile, all-solid-state batteries using solid electrolytes have the advantage of being able to produce electrode stacks in a safe and simple form because they exclude organic solvents.

[0009] The negative electrode, positive electrode, and solid electrolyte constituting the all-solid-state battery may be manufactured by mixing powder and solvent to prepare a slurry for the negative electrode, a slurry for the positive electrode, and a slurry for the solid electrolyte, respectively, and then coating and drying the same to manufacture the negative electrode, positive electrode, and solid electrolyte layers, and laminating these. Alternatively, after manufacturing the negative electrode, a slurry for the solid electrolyte may be coated on one surface of the negative electrode, and then dried to manufacture a negative electrode-solid electrolyte layer laminate, and a positive electrode may be laminated thereon to manufacture the all-solid-state battery. Since the positive electrode, negative electrode, and solid electrolyte layers are manufactured using slurry, the solvent may remain even if the drying step is performed. In addition, during the manufacturing process of the all-solid-state battery, moisture in the air may permeate the interior during the manufacturing process, causing moisture to remain.

[0010] The residual solvent and moisture can subsequently trigger side reactions within the all-solid-state battery, acting as resistance components and reducing the initial efficiency and capacity of the all-solid-state battery. Therefore, minimizing residual solvent and moisture during the manufacture of all-solid-state batteries remains a challenge.

[0011]

[0012] [Previous literature]

[0013] [Patent Document]

[0014] Republic of Korea Publication Patent No. 10-2014-0030431

[0015]

[0016] The purpose of the present invention is to provide an all-solid-state battery having excellent initial efficiency and lifespan characteristics by minimizing the content of solvent remaining in the all-solid-state battery.

[0017] In addition, the present invention aims to provide a method for manufacturing an all-solid-state battery capable of minimizing the content of solvent remaining in the all-solid-state battery.

[0018]

[0019] To achieve the above purpose,

[0020] The present invention relates to an all-solid-state battery comprising at least one unit cell including a positive electrode, a solid electrolyte layer, and a negative electrode,

[0021] An all-solid-state battery is provided, wherein a residual solvent content in one unit cell or a plurality of unit cells is 2500 ppm or less.

[0022] In one embodiment of the present invention, the residual solvent content in one unit cell or multiple unit cells may be 500 ppm or less.

[0023] In one embodiment of the present invention, the all-solid-state battery may be a monocell including one unit cell, a bicell including one or more unit cells, or a stack cell including a plurality of unit cells.

[0024] In one embodiment of the present invention, the all-solid-state battery may be stored in a storage compartment of a battery case.

[0025]

[0026] In addition, the present invention comprises: (1) a step of storing an all-solid-state battery in a storage portion of a battery case;

[0027] (2) A step of sealing three sides of a battery case adjacent to the above-mentioned all-solid-state battery to form a first sealing portion, and forming an open portion on the remaining side;

[0028] (3) A step of drying the all-solid-state battery at high temperature in a vacuum state through the opening of the battery case;

[0029] (4) A step of forming a cutting line along the edge of the all-solid-state battery adjacent to the all-solid-state battery in the above-mentioned opening, and sealing the outer surface between the cutting line and the all-solid-state battery in a vacuum state to form a second sealing portion; and

[0030] (5) A method for manufacturing an all-solid-state battery of the present invention is provided, including a step of cutting along the cutting line to remove excess portion.

[0031] In one embodiment of the present invention, the high-temperature drying may be performed at a temperature of 45 to 120°C for 30 minutes to 48 hours.

[0032] In one embodiment of the present invention, a step of pressurizing the all-solid-state battery may be additionally included after step (5).

[0033]

[0034] The all-solid-state battery of the present invention can suppress side reactions that may occur in an all-solid-state battery by minimizing the content of residual solvent, and can improve initial efficiency and life characteristics.

[0035]

[0036] Figure 1 is a cross-sectional view of a unit cell.

[0037] Figure 2 is a cross-sectional view of an all-solid-state battery in the form of a monocell containing one unit cell.

[0038] Figure 3 is a cross-sectional view of a bi-cell type all-solid-state battery including one unit cell.

[0039] Figure 4 is a cross-sectional view of an all-solid-state battery including a plurality of unit cells.

[0040] Figures 5 to 8 are drawings showing a method for manufacturing an all-solid-state battery of the present invention.

[0041] Figure 9 is a graph measuring the initial efficiency of the all-solid-state battery of Experimental Example 1.

[0042] Figure 10 is a graph measuring the capacity retention rate of the all-solid-state battery of Experimental Example 1.

[0043]

[0044] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0045] In order to clearly explain the present invention, parts that are not related to the description are omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0046] In addition, terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain the invention in the dictionary in the best way.

[0047] Hereinafter, embodiments will be described in detail with reference to the attached drawings. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0048]

[0049] The present invention relates to an all-solid-state battery.

[0050] The all-solid-state battery of the present invention (200) includes at least one unit cell (260) including a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230),

[0051] The residual solvent content in one unit cell or multiple unit cells may be less than 2500 ppm.

[0052]

[0053] The all-solid-state battery of the present invention may have a residual solvent content of one unit cell (260) or a plurality of unit cells (260) including a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230) of 2500 ppm or less, preferably 500 ppm or less. This residual solvent content is based on the unit cell (260) having a size of 20×20 mm and a weight of 250 g, but is not limited thereto. In the present invention, the plurality of unit cells (260) may be 2 to 100 unit cells (260), but may be more than that as needed, and the number of the plurality of unit cells is not particularly limited in the present invention.

[0054] If the residual solvent content of the above-mentioned one unit cell or multiple unit cells is 2500 ppm or less, problems such as side reactions, initial efficiency reduction, and capacity reduction arising from the residual solvent can be solved. Therefore, the all-solid-state battery of the present invention can have excellent initial efficiency and lifespan characteristics.

[0055] The content of the above residual solvent can be minimized by step (3) of the all-solid-state battery manufacturing method described later, and this will be described in detail in the all-solid-state battery manufacturing method described later.

[0056] In addition, the positive electrode (210) and negative electrode (230) of the above unit cell (260) may be excluded if they are dry positive electrodes and dry negative electrodes, respectively.

[0057] The above-mentioned all-solid-state battery (200) may be a monocell including one unit cell (260), a bicell including one or more unit cells (260), or a stack cell including multiple unit cells (260).

[0058] Figure 1 is a cross-sectional view of a unit cell, and referring to Figure 1, the unit cell (260) may include one each of an anode (210), a solid electrolyte layer (220), and a cathode (230).

[0059] Fig. 2 is a cross-sectional view of a monocell, and since the monocell includes only one unit cell (260), the monocell and the unit cell (260) may be the same. Therefore, the residual solvent content of the unit cell (260) may be the residual solvent content of the monocell. Referring to Fig. 1, the monocell may be formed by stacking a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230) in that order, and it may be preferable to stack a positive electrode current collector (210a) on the positive electrode (210) and a negative electrode current collector (230a) on the negative electrode (230) to form a positive electrode current collector (210a) and a negative electrode current collector (230a) as the outermost layer of the monocell.

[0060] Fig. 3 is a cross-sectional view of a bicell, and specifically, a cross-sectional view of an a-type bicell including one unit cell (260). The a-type bicell is formed by stacking a positive electrode (210), a solid electrolyte layer (220), a negative electrode (230), a solid electrolyte layer (220), and a positive electrode (210) in that order. Therefore, the a-type bicell may include one unit cell (260), and in the a-type bicell, the unit cell (260) may be stacked in the order of the positive electrode (210), the solid electrolyte layer (220), and the negative electrode (230), or may be stacked in the order of the negative electrode (230), the solid electrolyte layer (220), and the positive electrode (210). In addition, it may be preferable to stack a positive electrode current collector (210a) on the outermost layer of the a-type bicell to form a positive electrode current collector (210a) on the outermost layer of the a-type bicell.

[0061] In addition, the C-type bicell is laminated in the order of a negative electrode (230), a solid electrolyte layer (220), a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230). Therefore, the C-type bicell may include one unit cell (260), and in the C-type bicell, the unit cell (260) may be laminated in the order of a negative electrode (230), a solid electrolyte layer (220), and a positive electrode (210), or may be laminated in the order of a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230). In addition, it may be preferable to laminate a negative electrode current collector (230a) on the outermost layer of the C-type bicell to form a negative electrode current collector (230a) on the outermost layer of the C-type bicell.

[0062] The residual solvent content of the unit cell (260) included in the above-mentioned a-type bicelle or c-type bicelle may be 2500 ppm or less, preferably 500 ppm or less.

[0063] FIG. 4 is a cross-sectional view of a stack cell including a plurality of unit cells (260). In one embodiment, the stack cell may be manufactured by manufacturing a first stacked body in which a negative electrode current collector (230a), a negative electrode (230), a solid electrolyte layer (220), and a positive electrode (210) are stacked in that order, a second stacked body in which a positive electrode current collector (210a), a positive electrode (210), a solid electrolyte layer (220), and a negative electrode (230) are stacked in that order, and then alternately stacking the first stacked body and the second stacked body to manufacture the stack cell. For example, the positive electrode (210) may be stacked so that it is positioned on both sides of the positive electrode current collector (210a). In another example, the negative electrode (230) may be stacked so that it is positioned on both sides of the negative electrode current collector (230a). When the first stacked body and the second stacked body are alternately stacked, the outermost layer of the stack cell is the positive electrode (210) or the negative electrode (230). Therefore, it may be desirable to form a positive electrode current collector (210a) or a negative electrode current collector (230a) on the positive electrode (210) or negative electrode (230) of the outermost layer of the stack cell by stacking the positive electrode current collector (210a) or negative electrode current collector (230a).

[0064] Even if the stack cell includes a plurality of unit cells (260), the number of the anodes (210), solid electrolyte layers (220), and cathodes (230) included in the plurality of unit cells may not match the number of the anodes (210), solid electrolyte layers (220), and cathodes (230) included in the stack cell, depending on the stacking structure of the stack cell or the stacking method of the anodes (210), solid electrolyte layers (220), and cathodes (230).

[0065] The above stack cell includes a plurality of unit cells (260), and the content of residual solvent in the plurality of unit cells may be 2500 ppm or less, preferably 500 ppm or less.

[0066]

[0067] The positive electrode (210) includes a positive electrode active material and a solid electrolyte, and may additionally include a binder or a conductive material. The positive electrode (210) may be formed on one or both sides of a positive electrode current collector (210a). The positive electrode (210) may be formed by mixing a positive electrode active material, a solid electrolyte, and a solvent to prepare a slurry-type positive electrode forming composition, and then applying and drying the composition on the positive electrode current collector (210a). Alternatively, the positive electrode may be formed by applying and drying the positive electrode forming composition on one side of a release film, and then peeling the release film. The positive electrode (210) may be a dry positive electrode in which a positive electrode active material and a solid electrolyte are applied on the positive electrode current collector (210a) without a solvent.

[0068] The above 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; chemical formula Li 1+x Mn 2-x Lithium manganese oxides such as O4(0≤x≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, 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 expressed as 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-xLithium manganese composite oxides with spinel structure represented by O4; LiCoPO4; LiFePO4; Elemental sulfur (S8); Li2Sn(n=1), organosulfur compounds or carbon-sulfur polymers (C2S x ) n : It may include sulfur series compounds such as x=2.5 ~ 50, n≥2), but is not limited to these.

[0069] The above solid electrolyte may include at least one selected from the group consisting of a sulfide-based solid electrolyte, a polymer-based solid electrolyte, and an oxide-based solid electrolyte.

[0070] The above sulfide-based solid electrolyte contains sulfur (S) and has the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramic.

[0071] Specifically, the sulfide-based solid electrolyte may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, Li6PS5I, Li2S-P2S5, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, and Li2S-GeS2-ZnS, and preferably may include at least one selected from the group consisting of Li6PS5Cl, Li6PS5Br, and Li6PS5I. The above Li6PS5Cl, Li6PS5Br, and Li6PS5I may be argyrodite type solid electrolytes. In addition, the sulfide-based solid electrolyte may be in a form doped with trace elements, for example, Li6PS5Cl may be additionally doped with bromine (Br).

[0072] The above polymer-based solid electrolyte is a polymer electrolyte material formed by adding a polymer resin to a composite of a lithium salt and a polymer resin, that is, a solvated lithium salt, and is about 1x10 -7 S / cm or more, preferably about 1x10 -5 It can exhibit ionic conductivity of S / cm or more.

[0073] 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., and may include one or more of these. In addition, the polymer electrolyte may include, as a polymer resin, a branched copolymer in which an amorphous polymer such as PMMA, polycarbonate, polysiloxane (PDMS) and / or phosphazene is copolymerized as a comonomer in a polyethylene oxide (PEO) main chain, a comb-like polymer, and a cross-linked polymer resin, and may include one or more of these.

[0074] In the above polymer solid electrolyte, the above-mentioned lithium salt is an ionizable lithium salt, Li + X - It can be expressed as . There is no particular limitation on the anion of these lithium salts, but 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:

[0075] The above oxide-based solid electrolyte may contain oxygen (O) and have the ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table. For example, an LLTO-based compound, Li6La2CaTa2O 12 , Li6La2ANb2O 12 (A is Ca or Sr), Li2Nd3TeSbO 12 , Li3BO 2.5 N 0.5 , Li9SiAlO8, LAGP compounds, LATP compounds, Li1 +x Ti 2-x Al x Si y (PO4) 3-y (where, 0≤x≤1, 0≤y≤1), LiAl x Zr 2-x (PO4)3(where, 0≤x≤1, 0≤y≤1), LiTi x Zr 2-x (PO4)3 (wherein, 0≤x≤1, 0≤y≤1), may include at least one selected from among LISICON compounds, LIPON compounds, perovskite compounds, NASICON compounds, and LLZO compounds.

[0076] The above 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 the current collector to the positive electrode active material. Any material that does not cause chemical changes in a lithium secondary battery and has porosity and conductivity can be used without restriction.

[0077] For example, the conductive material may be a porous carbon-based material, such as carbon black, graphite, graphene, activated carbon, carbon fiber, etc.; metallic fibers such as metal mesh; metallic powders such as copper, silver, nickel, aluminum, etc.; or organic conductive materials such as polyphenylene derivatives. The conductive materials may be used alone or in combination.

[0078] Current commercially available products include acetylene black series (such as those from Chevron Chemical Company or Gulf Oil Company), Ketjen Black EC series (from Armak Company), Vulcan XC-72 (from Cabot Company), and Super P (from MMM). Examples include acetylene black, carbon black, and graphite.

[0079] In addition, the binder increases the bonding strength between the components constituting the positive electrode and between them and the current collector, and any binder known in the industry can be used.

[0080] For example, the binder may be a fluororesin binder including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber binder including styrene butadiene rubber (SBR), acrylonitrile-butidiene rubber, and styrene-isoprene rubber; a cellulose binder including carboxyl methyl cellulose (CMC), starch, hydroxy propyl cellulose, and regenerated cellulose; a polyalcohol binder; a polyolefin binder including polyethylene and polypropylene; a polyimide binder; a polyester binder; and a silane binder. One, two or more mixtures or copolymers selected from the group consisting of may be used.

[0081] The above positive electrode current collector (210a) can form fine irregularities on its surface to strengthen the bonding strength with the negative electrode active material, and can be used in various forms such as a film, sheet, foil, mesh, net, porous body, foam, and non-woven fabric.

[0082] The above negative electrode (230) includes a negative electrode active material and may additionally include a solid electrolyte or a binder. The negative electrode (230) may be formed on one side or both sides of a negative electrode current collector (230a). The negative electrode (230) may be formed by mixing a negative electrode active material and a solvent to prepare a slurry-type negative electrode forming composition, and then applying and drying the composition on the negative electrode current collector (230a). Alternatively, the negative electrode may be formed by applying and drying the negative electrode forming composition on one side of a release film, and then peeling the release film. The negative electrode (230) may be excluded from a dry negative electrode in which a negative electrode active material and a solid electrolyte are applied on the negative electrode current collector (230a) without a solvent. In addition, a case in which the negative electrode (230) is a lithium metal film containing 80 wt% or more of lithium metal may be excluded.

[0083] The above negative electrode active material may include at least one selected from a material capable of reversibly inserting and de-inserting lithium ions, lithium metal, or a metal material capable of being alloyed with lithium, and preferably includes at least one selected from a carbon-based negative electrode active material and a metal or metalloid negative electrode active material.

[0084] The above carbon-based negative electrode active material may be natural graphite, artificial graphite, or amorphous carbon, and the amorphous carbon may be carbon black, acetylene black, furnace black, ketjen black, graphene, or the like, but is not necessarily limited thereto.

[0085] The above metal or metalloid negative electrode active material includes at least one selected from the group consisting of 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 or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used. For example, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0086] In one specific example, the negative electrode active material may include only a carbon-based negative electrode active material, or, when the carbon-based negative electrode active material is amorphous carbon, may include at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In another specific example, the negative electrode active material may include a mixture of amorphous carbon and at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of the amorphous carbon and gold, etc., is, for example, a weight ratio of 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to this range.

[0087] The above negative electrode collector (230a) may be the same as the above-described positive electrode collector (210a).

[0088] The above solid electrolyte layer (220) may be manufactured by mixing solid electrolyte powder, a binder, and a solvent to prepare a slurry-type solid electrolyte layer forming composition, and then applying and drying the composition. In one embodiment, the composition may be applied and dried on a release film, and the release film may be peeled off to manufacture the solid electrolyte layer. In another embodiment, the composition may be applied and dried on a negative electrode active material layer to manufacture a negative electrode-solid electrolyte layer laminate.

[0089] The above solid electrolyte follows the above-described.

[0090] As described above, the positive electrode (210) is manufactured using a composition for forming a positive electrode, the solid electrolyte layer (220) is manufactured using a composition for forming a solid electrolyte layer, and the negative electrode (230) is manufactured using a composition for forming a negative electrode, and all of the compositions include a solvent. As the solvents of the compositions are dried, the positive electrode (210), the solid electrolyte layer (220), and the negative electrode (23) are formed. However, since the solvent is not completely dried, residual solvent may be generated in the positive electrode (210), the solid electrolyte layer (220), and the negative electrode (230). In addition, moisture and solvent in the air may permeate during the storage process of the all-solid-state battery (200) or the assembly process of the all-solid-state battery (200), resulting in residual moisture and solvent. Therefore, in the case where there is one or more unit cells (260) in the all-solid-state battery (200), the content of the residual solvent may be 2500 ppm or less, preferably 500 ppm or less.

[0091]

[0092] The above all-solid-state battery may include a positive electrode tab (not shown), a negative electrode tab (not shown), a positive electrode lead (240), and a negative electrode lead (250).

[0093] The above positive electrode tab may be integral with the positive electrode current collector (210a) or may be electrically connected to the positive electrode current collector (210a) by welding or the like. A positive electrode active material layer may not be formed on the positive electrode tab. The positive electrode current collector (210a) and the positive electrode lead (240) may be electrically connected through the positive electrode tab.

[0094] The above negative electrode tab may be integral with the negative electrode collector (230a) or may be electrically connected to the negative electrode collector (230a) by welding or the like. A negative electrode active material layer may not be formed on the negative electrode tab. The negative electrode collector (230a) and the negative electrode lead (250) may be electrically connected through the negative electrode tab.

[0095] The above-mentioned all-solid-state battery (200) may be stored in a storage compartment (110) of a battery case (100) including a storage compartment (110). The type of the battery case (100) is not limited as long as it is used in the art, and may be, for example, pouch-shaped, cylindrical, square, or coin-shaped.

[0096]

[0097] The present invention relates to a method for manufacturing an all-solid-state battery.

[0098] (1) A step of storing an all-solid-state battery in the storage compartment of a battery case (100);

[0099] (2) A step of sealing three sides of the battery case (100) adjacent to the above-mentioned all-solid-state battery to form a first sealing portion (120), and forming an open portion (140) on the remaining side;

[0100] (3) A step of drying the all-solid-state battery (200) at high temperature through the opening (140) of the battery case (100);

[0101] (4) A step of forming a cutting line (160) along the edge of the all-solid-state battery (200) adjacent to the all-solid-state battery (200) in the above-mentioned opening (140), and sealing the outer surface between the cutting line (160) of the battery case (100) and the all-solid-state battery (200) in a vacuum state to form a second sealing portion (130); and

[0102] (5) It may include a step of removing the excess portion (150) by cutting along the cutting line (160) of the battery case (100).

[0103]

[0104] Hereinafter, the method for manufacturing the all-solid-state battery of the present invention as described above will be described in detail with reference to the attached drawings.

[0105] Figures 5 to 8 are step-by-step schematic diagrams showing a method for manufacturing an all-solid-state battery of the present invention.

[0106] In FIGS. 5 to 8, the battery case (100) is illustrated as a pouch type, but the battery case (200) in the present invention is not limited to a pouch, and any battery case used in the industry can be used.

[0107]

[0108] The above step (1) is a step of storing an all-solid-state battery (200) in the storage portion (110) of the battery case (100).

[0109] Figure 5 is a drawing showing an all-solid-state battery (200) stored in a storage portion (110) of a battery case (100). The all-solid-state battery (200) is stored in the storage portion (110) of the battery case (100), and the positive electrode lead (240) and the negative electrode lead (250) of the all-solid-state battery (200) can protrude outside the battery case (100).

[0110]

[0111] The above step (2) is a step of forming a first sealing portion (120) by sealing three sides of the battery case (100) adjacent to the all-solid-state battery (200) as shown in FIG. 6, and forming an open portion (140) on the remaining side. That is, the sealing may be performed through thermal fusion. Since the open portion (140) is not sealed, residual solvent and moisture of the all-solid-state battery (200) can be removed through the open portion (140). Depending on the structure of the battery case (100), one of the three sides may already be sealed, in which case sealing may be performed on only two sides.

[0112]

[0113] The above step (3) is a step of drying the all-solid-state battery (200) at high temperature in a vacuum state through the opening (140) of the battery case (100).

[0114] As described above, the positive electrode (210) of the all-solid-state battery (200) is manufactured by applying a slurry-type positive electrode forming composition to a positive electrode collector (210a) and drying it, or by applying it to a release film, drying it, and then peeling off the release film. The negative electrode (230) is manufactured by applying a slurry-type negative electrode forming composition to a negative electrode collector (230a) and drying it, or by applying it to a release film, drying it, and then peeling off the release film. The solid electrolyte layer (220) is manufactured by applying a slurry-type solid electrolyte layer forming composition to a release film, drying it, and then peeling off the release film. Even if the positive electrode forming composition, the negative electrode forming composition, and the solid electrolyte layer forming composition are applied and then dried, a solvent may remain in the positive electrode (210), the negative electrode (230), and the solid electrolyte layer (220). In addition, during the process of manufacturing a monocell, stack cell, or bicell, moisture in the atmosphere may infiltrate, and the positive electrode (210), negative electrode (230), and solid electrolyte layer (220) of the all-solid-state battery (200) may contain residual solvent. The residual solvent may cause side reactions within the all-solid-state battery, acting as a resistance component and reducing the initial efficiency and capacity of the all-solid-state battery. Therefore, the amount of solvent remaining in the all-solid-state battery must be minimized.

[0115] The present invention can minimize residual solvent in an all-solid-state battery by drying the all-solid-state battery (200) located in the storage portion (110) inside the battery case (100) through the opening portion (140) at high temperature in a vacuum state in the step (3). In the case of a lithium secondary battery using a liquid electrolyte, the liquid electrolyte may evaporate if high temperature drying is performed in a vacuum state, and therefore the manufacturing method of the present invention can only be applied to an all-solid-state battery.

[0116] The above high-temperature drying may be a desolvation process and may be performed at a temperature of 45 to 120°C for 30 minutes to 48 hours. During the temperature and time, the solvent remaining in the all-solid-state battery may evaporate, thereby minimizing the residual solvent in the all-solid-state battery. The residual solvent content of a unit cell including one positive electrode (210), one solid electrolyte layer (220), and one negative electrode (230) in the all-solid-state battery (200) located in the storage compartment (110) inside the battery case (100) may be 2500 ppm or less, and preferably 500 ppm or less.

[0117]

[0118] The above step (4) is a step of forming a cutting line (160) along the edge of the all-solid-state battery (200) adjacent to the all-solid-state battery (200) at the opening (140) as shown in Fig. 7, and sealing the outer surface between the cutting line (160) of the battery case (100) and the all-solid-state battery (200) in a vacuum state to form a second sealing portion (130). The sealing may be performed by thermal fusion, and by forming the second sealing portion (130), the battery case (100) is in a sealed state.

[0119] The second sealing portion (130) may be formed in a vacuum state. If the second sealing portion (130) is not formed in a vacuum state, laboratory atmospheric components may remain inside the battery case (100), and the atmospheric components may react with the all-solid-state battery (200) stored in the storage portion (110) of the battery case, which may cause a problem. However, if the second sealing portion (130) is formed in a vacuum state, the above problem may not occur. In addition, since the second sealing portion (130) is formed in a vacuum state, the manufacturing method of the present invention cannot manufacture a lithium secondary battery using a liquid electrolyte, and can only manufacture an all-solid-state battery.

[0120]

[0121] The above step (5) is a step of removing the excess portion (150) by cutting along the cutting line (160) of the battery case (100) as shown in FIG. 8. When the second sealing portion (130) is formed, an unnecessary excess portion (150) is formed in the battery case (100). Therefore, by performing the step of removing the excess portion (150) by cutting along the cutting line (160), an all-solid-state battery can be finally manufactured.

[0122] In addition, a step of pressurizing the all-solid-state battery may be additionally included after the step (5).

[0123] As described above, the method for manufacturing an all-solid-state battery of the present invention can minimize the content of solvent remaining in the all-solid-state battery (200) by drying the all-solid-state battery (200) located inside the battery case (100) at high temperature through the opening (140) of the battery case (100) in step (3), thereby solving problems such as side reactions, initial efficiency reduction, and capacity reduction arising from the remaining solvent.

[0124] Therefore, the all-solid-state battery manufactured by the manufacturing method of the present invention can have excellent initial efficiency and lifespan characteristics.

[0125]

[0126] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0127]

[0128] <Manufacturing of all-solid-state batteries>

[0129] Example 1.

[0130] A positive electrode active material (NCM811 coated with LiNbO3), a conductive agent (amorphous carbon), a binder (SBR-based), and a solid electrolyte (Li6PS5Cl) were mixed in a ratio of 83:1:15:1, and added to a solvent to prepare a slurry-type positive electrode forming composition. The positive electrode forming composition was applied, dried, and rolled onto a positive electrode current collector to prepare a positive electrode.

[0131] A negative electrode active material (graphite), a solid electrolyte (Li6PS5Cl), and a binder (rubber series) were mixed in a ratio of 70:28:2, and added to a solvent to prepare a slurry-type negative electrode forming composition. The negative electrode forming composition was applied, dried, and rolled onto a negative electrode current collector (STS) to prepare a negative electrode.

[0132] Li6PS5Cl was used as a solid electrolyte, and this was added to a solvent to prepare a slurry-type solid electrolyte layer-forming composition, which was then applied onto a release film. Thereafter, the composition was dried in a vacuum for 5 hours, and the release film was removed to prepare a solid electrolyte layer.

[0133] The solid electrolyte layer was interposed between the positive and negative electrodes and pressurized to manufacture an all-solid-state battery. The all-solid-state battery includes one unit cell.

[0134] An all-solid-state battery was stored in the storage compartment of a pouch, which is a battery case, and three sides of the pouch adjacent to the all-solid-state battery were sealed. Thereafter, an opening was formed in the remaining unsealed side, and the all-solid-state battery was dried at high temperature at 100°C for 2 hours in a vacuum through the opening.

[0135] After that, the pouch was sealed by sealing the outer circumference between the cutting line of the pouch and the solid-state battery, and the excess was removed by cutting along the cutting line, and the solid-state battery was manufactured by pressing it.

[0136]

[0137] Comparative Example 1.

[0138] An all-solid-state battery was manufactured in the same manner as in Example 1 above.

[0139] An all-solid-state battery was manufactured by storing the all-solid-state battery in the storage compartment of the pouch and sealing the outer surface of the pouch.

[0140]

[0141] Experimental Example 1. Measurement of Residual Solvent Content in All-Solid-State Batteries

[0142] The residual solvent content of the unit cell in the all-solid-state battery manufactured in Example 1 and Comparative Example 1 was measured using Karl Fischer coulometry, and the size of the unit cell was 20×20 mm and 250 g.

[0143] As a result, the unit cell of the all-solid-state battery of Example 1 had a residual solvent content of 472.4 ppm, while the unit cell of Comparative Example 1 had a residual solvent content of 2560 ppm.

[0144] In Example 1, the all-solid-state battery was dried at high temperature in a vacuum state through the opening of the pouch during the manufacture of the all-solid-state battery, and in Comparative Example 1, high-temperature drying was not performed.

[0145] Therefore, it was confirmed that the unit cell of the all-solid-state battery of Example 1 had a minimized content of residual solvent.

[0146]

[0147] Experimental Example 2. Characteristic Evaluation of All-Solid-State Battery

[0148] The initial efficiency and capacity retention rate of the all-solid-state batteries of Example 1 and Comparative Example 1 were measured.

[0149] The all-solid-state batteries of Example 1 and Comparative Example 1 were each charged in CCCV mode at a temperature of 60°C at 0.05C, a charge voltage of 4.2 V, until a 0.01C cut-off was reached, and discharged in CC mode at 0.05C, a charge voltage of 3.0 V, to measure the initial efficiency when one charge / discharge cycle was performed, and the results are shown in Fig. 9.

[0150] Each of the all-solid-state batteries of Example 1 and Comparative Example 1 was charged in CCCV mode at a temperature of 60°C at 0.33C, a charge voltage of 4.2 V, and a 0.01C cut-off, and discharged in CC mode at 0.33C, a charge voltage of 3.0 V, and the capacity retention rate was measured when 100 charge / discharge cycles were performed, and the results are shown in Fig. 10.

[0151] In the initial efficiency measurement, the initial efficiency of the all-solid-state battery of Example 1 was 91.2%, and the initial efficiency of the all-solid-state battery of Comparative Example 1 was 85.3%.

[0152] In the capacity retention rate measurement, the initial capacity of the all-solid-state battery of Example 1 was 180 mAh / g, and the initial capacity of the all-solid-state battery of Comparative Example 1 was 162.9 mAh / g. In addition, the discharge capacity of the all-solid-state battery of Example 1 after 100 cycles was 164.2 mAh / g, and the initial capacity of the all-solid-state battery of Comparative Example 1 was 145.8 mAh / g, and from this, it was confirmed that the capacity retention rate of the all-solid-state battery of Example 1 was 91.2%, and the capacity retention rate of the all-solid-state battery of Comparative Example 1 was 89.5%.

[0153] The all-solid-state battery of Example 1 was manufactured by including a step of drying the all-solid-state battery at high temperature in a vacuum state through an opening of a pouch, and by minimizing the residual solvent of the unit cell in the all-solid-state battery located inside the pouch, the all-solid-state battery showed excellent results in initial efficiency and capacity retention.

[0154] The all-solid-state battery of Comparative Example 1 was manufactured without performing a step of high-temperature drying of the all-solid-state battery in a vacuum state through the opening of the pouch, and the residual solvent in the unit cell of the all-solid-state battery located inside the pouch was about 5 times more than that of Example 1, and as a result, the initial efficiency and capacity retention rate of the all-solid-state battery showed worse results than those of Example 1.

[0155] From the above results, it was found that the initial efficiency and capacity retention rate of the all-solid-state battery can be improved by performing a step of high-temperature drying of the all-solid-state battery in a vacuum state through an opening of the battery case to reduce the content of residual solvent in the all-solid-state battery located inside the battery case.

[0156]

[0157] [Explanation of symbols]

[0158] 100: Battery case 110: Storage compartment

[0159] 120: 1st sealing part 130: 2nd sealing part

[0160] 140: Open part 150: Surplus part

[0161] 160: Cutting line 200: All-solid-state battery

[0162] 210: Anode 210a: Anode current collector

[0163] 220: Solid electrolyte layer 230: Cathode

[0164] 230a: Negative current collector 240: Positive lead

[0165] 250: Cathode lead 260: Unit cell

Claims

1. An all-solid-state battery comprising at least one unit cell including a positive electrode, a solid electrolyte layer, and a negative electrode, An all-solid-state battery having a residual solvent content of 2500 ppm or less in one unit cell or a plurality of unit cells.

2. In the above paragraph 1, An all-solid-state battery having a residual solvent content of 500 ppm or less in one or more unit cells.

3. In the above paragraph 1, The above all-solid-state battery is an all-solid-state battery that is a monocell including one unit cell, a bicell including one or more unit cells, or a stack cell including multiple unit cells.

4. In the above paragraph 1, The above all-solid-state battery is an all-solid-state battery stored in a storage compartment of a battery case. 5.(1) A step of storing an all-solid-state battery in a storage compartment of a battery case; (2) A step of sealing three sides of a battery case adjacent to the above-mentioned all-solid-state battery to form a first sealing portion, and forming an open portion on the remaining side; (3) A step of drying the all-solid-state battery at high temperature in a vacuum state through the opening of the battery case; (4) A step of forming a cutting line along the edge of the all-solid-state battery adjacent to the all-solid-state battery in the above-mentioned opening, and sealing the outer surface between the cutting line and the all-solid-state battery in a vacuum state to form a second sealing portion; and (5) A method for manufacturing an all-solid-state battery according to claim 1, comprising the step of cutting along the above-mentioned cutting line to remove excess portion.

6. In paragraph 5, A method for manufacturing an all-solid-state battery, wherein the high-temperature drying is performed at a temperature of 45 to 120°C for 30 minutes to 48 hours.

7. In paragraph 5, A method for manufacturing an all-solid-state battery, further comprising a step of pressurizing the all-solid-state battery after the above step (5).

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