Manufacturing method of all-solid rechargeable battery

Abstract

Provided is a manufacturing method of an all-solid rechargeable battery. The manufacturing method of an all-solid rechargeable battery, according to an embodiment, comprises: a first step for attaching an atypical reel-type thin film sheet to a carrier film; a second step for continuously supplying a negative electrode plate provided with a solid electrolyte layer; a third step for attaching the thin film sheet to the solid electrolyte layer and then removing the carrier film; a fourth step for notching the thin film sheet, the solid electrolyte layer, and the negative electrode plate; a fifth step for pressing and attaching the thin film sheet to the solid electrolyte layer; a sixth step for inserting a positive electrode plate over the solid electrolyte layer inside the thin film sheet; and a seventh step for forming a unit cell by cutting the thin film sheet, the solid electrolyte layer, and the negative electrode plate.

Description

Manufacturing method of all-solid-state secondary battery

[0001] The present disclosure relates to a method for manufacturing an all-solid-state secondary battery.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0003] Lithium-ion batteries currently on the market use electrolytes containing flammable organic solvents, which poses a risk of overheating and fire in the event of a short circuit. To address this issue, all-solid-state secondary batteries using solid electrolytes are being proposed.

[0004] All-solid-state secondary batteries do not use flammable organic solvents, significantly reducing the risk of fire or explosion even if a short circuit occurs. Therefore, these all-solid-state batteries significantly improve safety compared to lithium-ion batteries that use electrolytes.

[0005] The above-described information disclosed in the background technology of this invention is only intended to improve understanding of the background of the present disclosure and may therefore include information that does not constitute prior art.

[0006] One embodiment provides a method for manufacturing an all-solid-state secondary battery by attaching a thin film sheet to a carrier film and continuously supplying it in a reel form to improve productivity.

[0007] A method for manufacturing an all-solid-state secondary battery according to one embodiment includes a first step of attaching an irregular reel-type thin film sheet to a carrier film, a second step of continuously supplying a negative electrode plate having a solid electrolyte layer, a third step of attaching the thin film sheet to the solid electrolyte layer and then removing the carrier film, a fourth step of notching the thin film sheet, the solid electrolyte layer, and the negative electrode plate, a fifth step of pressurizing and attaching the thin film sheet to the solid electrolyte layer, a sixth step of inserting a positive electrode plate onto the solid electrolyte layer inside the thin film sheet, and a seventh step of cutting the thin film sheet, the solid electrolyte layer, and the negative electrode plate to form a unit cell.

[0008] The above first step may further attach a cover film to the inner surface of the carrier film.

[0009] The first step may include attaching the thin film sheet by interposing an adhesive on the outer inner surface of the carrier film, and separating the cover film from the adhesive.

[0010] The fourth step above can notch the tab while notching the negative electrode plate.

[0011] The above fifth step can be applied by pressure attachment using a roll press.

[0012] The sixth step can adhere the outer side of the positive electrode plate to the inner side of the thin film sheet.

[0013] The seventh step cuts the thin film sheet positioned between the adjacent positive electrode plates, so that the thin film sheet, the solid electrolyte layer, and the outer surface of the negative electrode plate can form a straight line in the thickness direction.

[0014] The seventh step can bring the outer surface of the positive electrode plate and the inner surface of the thin film sheet into surface contact with each other.

[0015] The seventh step can form the unit cell into a monocell by cutting the thin film sheet that accommodates the positive electrode plate, the solid electrolyte layer, and the negative electrode plate.

[0016] The above thin film sheet includes a first thin film sheet and a second thin film sheet, the carrier film includes a first carrier film and a second carrier film, and the first step can attach the first thin film sheet to the first carrier film and attach the second thin film sheet to the second carrier film.

[0017] The above solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, and the second step can continuously supply a negative electrode plate having the first solid electrolyte layer and the second solid electrolyte layer on both sides.

[0018] In the third step, the first thin film sheet and the second thin film sheet are attached to the first solid electrolyte layer and the second solid electrolyte layer provided on both sides of the negative electrode plate, respectively, and then the first carrier film and the second carrier film can be removed, respectively.

[0019] The above-described positive electrode plate includes a first positive electrode plate and a second positive electrode plate, and the sixth step may insert the first positive electrode plate onto the first solid electrolyte layer inside the first thin film sheet attached to the first solid electrolyte layer, and insert the second positive electrode plate onto the second solid electrolyte layer inside the second thin film sheet attached to the second solid electrolyte layer.

[0020] The seventh step may be performed by cutting the first thin film sheet, the negative electrode plate, and the second thin film sheet positioned between the neighboring first positive electrode plates in the first solid electrolyte layer, and the second thin film sheet positioned between the neighboring second positive electrode plates in the second solid electrolyte layer, so that the outer surfaces of the first thin film sheet, the first solid electrolyte layer, the negative electrode plate, the second solid electrolyte layer, and the second thin film sheet may be formed in a straight line in the thickness direction.

[0021] The seventh step may allow the outer surfaces of the first positive electrode plate and the second positive electrode plate and the inner surfaces of the first thin film sheet and the second thin film sheet to come into surface contact with each other.

[0022] The seventh step may form the unit cell into a bi-cell by cutting the first thin film sheet that accommodates the first positive electrode plate, the first solid electrolyte layer, the negative electrode plate, and the second thin film sheet that accommodates the second positive electrode plate and the second solid electrolyte layer.

[0023] In one embodiment, a thin film sheet is attached to a carrier film and continuously supplied in a reel form, the thin film sheet is attached to a solid electrolyte layer and then removed, a positive electrode plate is inserted into a space formed by the thin film sheet and the solid electrolyte layer, and the thin film sheet, the solid electrolyte layer, and the negative electrode plate are cut to form a unit cell. Therefore, one embodiment can improve the productivity of an all-solid-state secondary battery.

[0024] Additionally, since the thin film sheets are connected, no gaps are formed in the planes corresponding to adjacent unit cells. Therefore, cracks are prevented from occurring in the active material of the positive electrode plate inserted into the thin film sheets, thereby reducing the possibility of a short circuit occurring.

[0025] In addition, since the outer surface of the positive electrode plate and the inner surface of the thin film sheet are in surface contact with each other, the formation of a stepped structure, i.e., a step difference, in the height direction between the positive electrode plate and the solid electrolyte layer is prevented. Accordingly, the occurrence of cracks in the active material of the positive electrode plate is prevented, and thus, the possibility of a short circuit can be reduced.

[0026] Figure 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment of the present invention.

[0027] FIG. 2 is a cross-sectional view showing the formation of a lithium metal layer of an all-solid-state secondary battery according to one embodiment.

[0028] Figure 3 is a flowchart of a method for manufacturing an all-solid-state secondary battery according to a first embodiment of the present invention.

[0029] Figure 4 is a cross-sectional view of a thin film sheet attached to a carrier film.

[0030] FIG. 5 is a plan view of a state in which a thin film sheet attached to a carrier film is attached to a negative electrode plate having a solid electrolyte layer during the manufacturing method of FIG. 3, and then the carrier film is removed.

[0031] Figure 6 is a plan view of forming a tab by notching a thin film sheet, a solid electrolyte layer, and a negative electrode plate in the manufacturing method of Figure 3.

[0032] Figure 7 is a plan view of the thin film sheet, solid electrolyte layer, negative electrode plate, and tab formed after the notching of Figure 6.

[0033] Figure 8 is a cross-sectional view taken along line Ⅷ-Ⅷ of Figure 7.

[0034] Figure 9 is a plan view showing the thin film sheet being pressurized and attached to the solid electrolyte layer after the notching of Figure 6.

[0035] Figure 10 is a plan view of the positive electrode plate inserted onto the solid electrolyte layer inside the thin film sheet after the pressurized attachment of Figure 9.

[0036] Figure 11 is a plan view showing the formation of a unit cell by cutting a thin film sheet, a solid electrolyte layer, and a negative electrode plate after insertion of Figure 10.

[0037] Fig. 12 is a plan view of a thin film sheet applied to the unit cell of Fig. 11.

[0038] Fig. 13 is a cross-sectional view of an all-solid-state secondary battery unit cell cut along line ⅩⅢ-ⅩⅢ of Fig. 11.

[0039] FIG. 14 is a cross-sectional view of a method for manufacturing an all-solid-state secondary battery according to a second embodiment of the present invention, which supplies a negative electrode plate having first and second solid electrolyte layers on both sides.

[0040] Fig. 15 is a cross-sectional view of the manufacturing method of Fig. 14, in which the first and second thin film sheets attached to the first and second carrier films are attached to the negative electrode plate having the first and second solid electrolyte layers.

[0041] Figure 16 is a cross-sectional view of Figure 15 with the carrier film removed.

[0042] Fig. 17 is a cross-sectional view of adjacent unit cells cut after inserting the first and second positive electrode plates in Fig. 16 and before cutting the first and second thin film sheets and the first and second solid electrolyte layers and the negative electrode plate.

[0043] FIG. 18 is a cross-sectional view of a unit cell of an all-solid-state secondary battery after forming and cutting the unit cell in a method for manufacturing an all-solid-state secondary battery according to a second embodiment of the present invention.

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

[0045] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0046] To clearly illustrate various layers and regions in the drawings, their thicknesses are enlarged, and similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" or "on" another element, this includes not only the case where it is "directly over" the other element, but also the case where there is another element in between. Conversely, when an element is said to be "directly over" another element, it means that there is no other element in between.

[0047] Furthermore, the term "layer" here includes not only shapes formed on the entire surface when observed in a plan view, but also shapes formed on a portion of the surface. Here, "or" is not interpreted in an exclusive sense; for example, "A or B" is interpreted to include A, B, A+B, etc.

[0048] Cathode for all-solid-state secondary batteries

[0049] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, comprising a current collector and a positive electrode active material layer positioned on the current collector, wherein the positive electrode active material layer comprises at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material. However, without limitation thereto, the positive electrode for an all-solid-state secondary battery may comprise more or less components than the components described above.

[0050] In one embodiment, the positive electrode for the all-solid-state secondary battery is manufactured by applying a positive electrode composition including at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive agent to a current collector, followed by drying and rolling.

[0051] positive electrode active material

[0052] The above-mentioned positive electrode active material can be applied without limitation as long as it is generally used in all-solid-state secondary batteries. For example, the above-mentioned positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0053] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0054] Li a A 1-b X b O 2-c D c(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0055] Li a HAVE BEEN 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0056] Li a HAVE BEEN 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0057] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0058] Li a Ni 1-b-c Co b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0059] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0060] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0061] Li a Ni1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0062] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0063] Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0064] Li a Ni b Co c Mr d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0065] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0066] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0067] Li a Mr 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0068] Li a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0069] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0070] QO2; QS2; LiQS2;

[0071] V2O5; LiV2O5;

[0072] LiZO2;

[0073] LiNiVO4;

[0074] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0075] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0076] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0077] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0078] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate (LFP).

[0079] The above positive electrode active material may include a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, or a combination thereof.

[0080] [Chemical Formula 1]

[0081] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0082] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M 2 is one or more elements independently selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0083] [Chemical Formula 2]

[0084] Li a2 Co x2 M 3 1-x2 O2

[0085] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0086] [Chemical Formula 3]

[0087] Li a3 Fe x3 M 4 (1-x3) PO4

[0088] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0089] The average particle diameter (D50) of the positive electrode active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 5 μm to 25 μm, 5 μm to 20 μm, 8 μm to 20 μm, or 10 μm to 18 μm. A positive electrode active material having such a particle diameter range can be harmoniously mixed with other components within the positive electrode active material layer and can realize high capacity and high energy density.

[0090] The above-mentioned positive electrode active material may be in the form of a secondary particle formed by agglomeration of a plurality of primary particles, or may be in the form of a single particle. In addition, the above-mentioned positive electrode active material may be spherical or nearly spherical in shape, or may be polyhedral or irregular in shape.

[0091] Sulfide-based solid electrolyte

[0092] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, for example, I or Cl), 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 Sn (m, n are integers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or a combination thereof.

[0093] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or 50:50 to 80:20, and optionally heat-treating them. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0094] Methods for mixing sulfur-containing raw materials for producing sulfide-based solid electrolytes include mechanical milling or the solution method. Mechanical milling involves placing the starting raw materials in a reactor and vigorously stirring them with a ball mill or similar device to finely atomize and mix them. Using the solution method, the starting raw materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can solidify the crystals of the solid electrolyte and improve ionic conductivity. For example, a sulfide-based solid electrolyte can be produced by mixing sulfur-containing raw materials and heat-treating them twice or more, resulting in a sulfide-based solid electrolyte with high ionic conductivity and robustness.

[0095] For example, the sulfide-based solid electrolyte particles may include argyrodite-type sulfides. The argyrodite-type sulfides may include, for example, Li a M b P c S d A e(wherein a, b, c, d and e are all 0 or more and 12 or less, M is a metal other than Li or a combination of multiple metals other than Li, and A is F, Cl, Br, or I) and a specific example is Li 7-x PS 6-x A x (x is 0.2 or more and 1.8 or less, and A is F, Cl, Br, or I) can be expressed by the chemical formula. The above argyrodite-type sulfide is specifically Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0096] Sulfide-based solid electrolyte particles containing these argyrodite-type sulfides have an ionic conductivity of 10, which is the ionic conductivity of a typical liquid electrolyte at room temperature. -4 10 inland -2 It has a high ionic conductivity approaching the S / cm range, can form a close bond between a positive electrode active material and a solid electrolyte without causing a decrease in ionic conductivity, and can further form a close interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0097] An argyrodite-type sulfide-based solid electrolyte can be prepared, for example, by mixing lithium sulfide, phosphorus sulfide, and optionally, a lithium halide. After mixing, a heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0098] According to one embodiment, the average particle diameter (D50) of the sulfide-based solid electrolyte particles may be 5.0 ㎛ or less, for example, 0.1 ㎛ to 5.0 ㎛, 0.1 ㎛ to 4.0 ㎛, 0.1 ㎛ to 3.0 ㎛, 0.5 ㎛ to 2.0 ㎛, or 0.1 ㎛ to 1.5 ㎛. Alternatively, the sulfide-based solid electrolyte particles may be small particles having an average particle diameter (D50) of 0.1 ㎛ to 1.0 ㎛, or may be large particles having an average particle diameter (D50) of 1.5 ㎛ to 5.0 ㎛, depending on the location or purpose of use. The sulfide-based solid electrolyte particles having such a particle diameter range can effectively penetrate between solid particles in a battery, and have excellent contact with an electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured from a microscope image, for example, by measuring the sizes of about 20 particles in a scanning electron microscope image to obtain a particle size distribution and calculating D50 from this.

[0099] The content of the solid electrolyte in the positive electrode for the all-solid-state battery may be 0.5 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. This is the content relative to the total weight of components in the positive electrode, and specifically, it can be said to be the content relative to the total weight of the positive electrode active material layer.

[0100] In one embodiment, the positive electrode active material layer may include 50 wt% to 99.35 wt% of the positive electrode active material, 0.5 wt% to 35 wt% of the sulfide-based solid electrolyte, 0.1 wt% to 10 wt% of the fluorine-based resin binder, and 0.05 wt% to 5 wt% of the vanadium oxide, based on 100 wt% of the positive electrode active material layer. When this content range is satisfied, the positive electrode for an all-solid-state secondary battery can implement high capacity and high ionic conductivity while maintaining high adhesiveness, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0101] bookbinder

[0102] The binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector, and representative examples thereof include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0103] Challenge

[0104] The above-described positive electrode active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode, and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, and the like in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or combinations thereof.

[0105] The conductive material may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on the total weight of each component of the positive electrode for the all-solid-state battery, or based on the total weight of the positive electrode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0106] When the positive electrode active material layer further includes a conductive material, the positive electrode active material layer may include 45 wt% to 99.25 wt% of the positive electrode active material, 0.5 wt% to 35 wt% of the sulfide-based solid electrolyte, 0.1 wt% to 10 wt% of the fluorine-based resin binder, 0.05 wt% to 5 wt% of the vanadium oxide, and 0.1 wt% to 5 wt% of the conductive material, based on 100 wt% of the positive electrode active material layer.

[0107] Meanwhile, the positive electrode for the lithium secondary battery may further include an oxide-based inorganic solid electrolyte in addition to the above-described solid electrolyte. The oxide-based inorganic solid electrolyte may be, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y(PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or a combination thereof.

[0108] All-solid-state secondary battery

[0109] In one embodiment, an all-solid-state secondary battery is provided, which includes the aforementioned positive electrode and negative electrode and a solid electrolyte layer positioned between the positive electrode and negative electrode. The all-solid-state secondary battery may also be referred to as an all-solid-state battery or an all-solid-state lithium secondary battery.

[0110] Fig. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to Fig. 1, the all-solid-state secondary battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative electrode current collector (401) and a negative electrode active material layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode current collector (201) are laminated is housed in a case such as a pouch. The all-solid-state secondary battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). Although Fig. 1 illustrates one electrode assembly including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies.

[0111] cathode

[0112] An anode for an all-solid-state battery may include, for example, a current collector and a layer of anode active material positioned on the current collector. The layer of anode active material includes a cathode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0113] The above negative active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0114] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0115] As the above lithium metal alloy, an alloy of lithium and one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0116] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and the Si-based negative electrode active material may be silicon, a silicon-carbon composite, or SiO. x(0<x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0117] The silicon-carbon composite may be, for example, a silicon-carbon composite including a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. As the amorphous carbon precursor, coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin may be used. At this time, the content of silicon may be 10 wt% to 50 wt% with respect to the total weight of the silicon-carbon composite. In addition, the content of the crystalline carbon may be 10 wt% to 70 wt% with respect to the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20 wt% to 40 wt% with respect to the total weight of the silicon-carbon composite. In addition, the thickness of the amorphous carbon coating layer may be 5 nm to 100 nm.

[0118] The average particle diameter (D50) of the above silicon particles may be 10 nm to 20 μm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, and at this time, the atomic content ratio of Si:O in the silicon particles, which indicates the degree of oxidation, may be 99:1 to 33:67. The silicon particles may be SiO x It can be a particle, in which case SiO x In the range of x, it can be greater than 0 and less than 2. Here, the average particle diameter (D50) is measured by a particle size analyzer using laser diffraction and means the diameter of particles having a cumulative volume of 50% by volume in the particle size distribution.

[0119] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material can be 1:99 to 90:10 by weight.

[0120] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0121] In one embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. In addition, when the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0122] The above binder serves to adhere the negative active material particles well to each other and also to adhere the negative active material well to the current collector. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0123] The above-described non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0124] The water-soluble binder may be a rubber-based binder or a polymer resin binder. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0125] When a water-soluble binder is used as the negative electrode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, an alkali metal salt thereof, or a combination thereof. Na, K, or Li may be used as the alkali metal. The amount of the thickener used may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0126] The conductive material is used to provide conductivity to the electrode, and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0127] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0128] As another example, the negative electrode for the all-solid-state battery may be a precipitation-type negative electrode. The precipitation-type negative electrode refers to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which lithium metal or the like is precipitated when the battery is charged, and this acts as a negative electrode active material.

[0129] FIG. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation-type negative electrode according to one embodiment. Referring to FIG. 2, the precipitation-type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) positioned on the current collector. An all-solid-state battery including such a precipitation-type negative electrode (400') starts initial charging in a state in which no negative electrode active material is present, and upon charging, high-density lithium metal or the like is precipitated between the current collector (401) and the negative electrode coating layer (405) to form a lithium metal layer (404), which may function as a negative electrode active material. Accordingly, in an all-solid-state battery that has been charged at least once, the precipitation-type negative electrode (400') may include a current collector (401), a lithium metal layer (404) positioned on the current collector, and a negative electrode coating layer (405) positioned on the metal layer. The above lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and may be referred to as a metal layer or a negative electrode active material layer.

[0130] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0131] The metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one type of these or may be composed of an alloy of several types. When the metal is present in the form of particles, the average particle diameter (D50) thereof may be about 4 μm or less, for example, 10 nm to 4 μm.

[0132] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0133] When the above-described negative electrode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-described negative electrode coating layer (405) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0134] The above cathode coating layer (405) may include, for example, the metal and amorphous carbon, in which case it can effectively promote the precipitation of lithium metal.

[0135] The above cathode coating layer (405) may further include a binder, and the binder may be a conductive binder. In addition, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0136] The thickness of the cathode coating layer (405) may be, for example, 100 nm to 20 ㎛, or 500 nm to 10 ㎛, or 1 ㎛ to 5 ㎛.

[0137] The above-described precipitated negative electrode (400') may further include, for example, a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one type thereof or may be composed of multiple types of alloys. The thin film may further flatten the precipitated form of the lithium metal layer (404) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0138] solid electrolyte layer

[0139] The solid electrolyte layer (300) may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, etc. The specific details of the sulfide-based solid electrolyte and the oxide-based solid electrolyte are as described above.

[0140] In one example, the solid electrolyte included in the positive electrode (200) and the solid electrolyte included in the solid electrolyte layer (300) may include the same compound or different compounds. For example, when both the positive electrode (200) and the solid electrolyte layer (300) include an argyrodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. In addition, for example, when both the positive electrode (200) and the solid electrolyte layer (300) include the above-described coated solid electrolyte, the all-solid-state secondary battery may implement high capacity and high energy density while implementing excellent initial efficiency and lifespan characteristics.

[0141] Meanwhile, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (200) may be smaller than the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (300). In this case, the energy density of the all-solid-state battery can be maximized while increasing the mobility of lithium ions, thereby improving the overall performance. For example, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (200) may be 0.1 ㎛ to 1.0 ㎛, or 0.1 ㎛ to 0.8 ㎛, and the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (300) may be 1.5 ㎛ to 5.0 ㎛, or 2.0 ㎛ to 4.0 ㎛, or 2.5 ㎛ to 3.5 ㎛. When this particle size range is satisfied, the energy density of the all-solid-state secondary battery can be maximized while lithium ion transport is facilitated, resistance is suppressed, and the overall performance of the all-solid-state secondary battery can be improved. Here, the average particle diameter (D50) of the solid electrolyte can be measured using a particle size analyzer using laser diffraction. Alternatively, the particle size can be measured by selecting 20 or so random particles from a microscope image such as a scanning electron microscope, obtaining a particle size distribution, and calculating the D50 value from this.

[0142] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. At this time, the binder may be styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, but is not limited thereto, and any binder used in the relevant technical field may be used. The acrylate polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0143] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent of the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the solid electrolyte layer formation process is widely known in the art, a detailed description thereof will be omitted.

[0144] The thickness of the solid electrolyte layer may be, for example, 10 ㎛ to 150 ㎛.

[0145] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0146] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt may improve ion conductivity by enhancing the lithium ion mobility of the solid electrolyte layer.

[0147] The above lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0148] In addition, the lithium salt may be an imide-based one, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0149] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0150] The above ionic liquid may be a compound including a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) one or more anions selected from BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, Cl-, Br-, I-, BF4-, SO4-, CF3SO3-, (FSO2)2N-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, and (CF3SO2)2N-.

[0151] The ionic liquid may be at least one selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0152] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0153] The above-mentioned all-solid-state battery may be a unit battery having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit battery is repeated.

[0154] The shape of the above-mentioned all-solid-state battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. In addition, the above-mentioned all-solid-state battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring large amounts of power storage, and for example, it can be used in electric bicycles or power tools.

[0155] All-solid-state secondary batteries utilize solid electrolytes, so they pose a relatively lower risk of short circuits than conventional lithium-ion batteries. Specifically, all-solid-state secondary batteries comprise a cathode, a solid electrolyte layer, a cathode, and an elastic layer. Furthermore, to prevent short circuits between the anode and cathode, all-solid-state secondary batteries additionally include thin film sheets positioned on the outer surfaces of the anode and cathode.

[0156] For example, the thin film sheet may have a rectangular frame shape or a similar irregular shape. The attachment of the thin film sheet may be performed through a process of transporting and attaching individual units of the thin film sheet. Methods for attaching the thin film sheet include a heat pressing method, which applies pressure using a heated press, and a laminating method, which attaches the thin film sheet by passing it between heated rollers.

[0157] When placing an irregularly shaped thin film sheet on an electrode plate, precise attachment of the thin film sheet to the electrode plate is difficult due to the irregular shape of the thin film sheet. Consequently, a gap may be generated in the plane between adjacent thin film sheets, and a step structure, i.e., a height difference, may be formed at the ends of the electrode plate and the thin film sheet.

[0158] The gaps in the plane between the thin film sheets and the step structures in the height direction between the thin film sheets and the electrode plate, i.e., the steps, can cause cracks in the active material of the electrode plate, thereby increasing the possibility of a short circuit.

[0159] One embodiment is a method for producing an all-solid-state secondary battery, in which a thin film sheet to be attached to an electrode plate is continuously supplied and attached, and then cut, thereby eliminating gaps between thin film sheets and height differences between the thin film sheets and the electrode plate, and overcoming a decrease in productivity that occurs when the thin film sheets are individually supplied and attached to the electrode plate.

[0160] In addition, one embodiment can eliminate problems caused by the irregular shape of the thin film sheet when continuously supplying the thin film sheet by manufacturing it in a reel type. For example, problems such as the inability to run the thin film sheet, distortion of the attachment surface of the thin film sheet, and wrinkles occurring during attachment can be eliminated.

[0161] Figure 3 is a flowchart of a method for manufacturing an all-solid-state secondary battery according to a first embodiment of the present invention. Referring to Figure 3, the manufacturing method of the first embodiment includes a first step (ST1), a second step (ST2), a third step (ST3), a fourth step (ST4), a fifth step (ST5), a sixth step (ST6), and a seventh step (ST7) to manufacture an all-solid-state secondary battery.

[0162] Fig. 13 is a cross-sectional view of an all-solid-state secondary battery unit cell cut along line ⅩⅢ-ⅩⅢ of Fig. 11. Referring to Fig. 13, an all-solid-state secondary battery (1) manufactured by the manufacturing method of Fig. 3 includes a laminated negative electrode plate (11), a solid electrolyte layer (12), a positive electrode plate (13), and a thin film sheet (14).

[0163] Fig. 4 is a cross-sectional view of a thin film sheet attached to a carrier film. Referring to Figs. 3 and 4, the first step (ST1) attaches an irregular reel-type thin film sheet (14) to a carrier film (20). The first step (ST1) attaches the thin film sheet (14) to one surface of the carrier film (20) by interposing a first adhesive (14a). Therefore, the thin film sheet (14) can be continuously supplied using the carrier film (20) as a medium.

[0164] Step 1 (ST1) further attaches a cover film (21) to the inner surface of the carrier film (20). That is, a cover film (21) is further provided on the inner surface of the carrier film (20). The cover film (21) can protect the solid electrolyte layer (12) by preventing the carrier film (20) from contacting the solid electrolyte layer (12) when attaching the thin film sheet (14) to the solid electrolyte layer (12). Therefore, the cover film (21) is formed of a material capable of protecting the solid electrolyte layer (12).

[0165] The solid electrolyte layer (12) is laminated and attached to the negative electrode plate (11). Therefore, the exact position of the thin film sheet (14) in the solid electrolyte layer (12) can be viewed as the exact position of the thin film sheet (14) in the negative electrode plate (11).

[0166] Step 1 (ST1) involves attaching a thin film sheet (14) to the inner surface of the outer surface of a carrier film (20) by interposing a first adhesive (14a), and separating a cover film (21) from the first adhesive (14a). The first adhesive (14a) maintains adhesion between the carrier film (20) and the thin film sheet (14) until the thin film sheet (14) is attached to the solid electrolyte layer (12), and has an adhesive strength that allows the carrier film (20) to be easily separated from the thin film sheet (14) after the thin film sheet (14) is attached to the solid electrolyte layer (12).

[0167] The thin film sheet (14) further includes a second adhesive (14b) on the opposite side of the first adhesive (14a). Therefore, the thin film sheet (14) is attached to the solid electrolyte layer (12) via the second adhesive (14b). When the first adhesive (14a) separates the carrier film (20) from the thin film sheet (14), the second adhesive (14b) must maintain the thin film sheet (14) in a state of being attached to the solid electrolyte layer (12). Therefore, the adhesive strength of the second adhesive (14b) must be greater than that of the first adhesive (14a).

[0168] FIG. 5 is a plan view of a state in which a thin film sheet attached to a carrier film is attached to a negative electrode plate having a solid electrolyte layer during the manufacturing method of FIG. 3, and then the carrier film is removed.

[0169] Referring to FIGS. 1 and 5, the second step (ST2) continuously supplies a negative electrode plate (11) having a solid electrolyte layer (12). The negative electrode plate (11) is continuously supplied, and the solid electrolyte layer (12) is continuously provided on the negative electrode plate (11) so that it can correspond to a unit cell even when a thin film sheet (14) is attached. The negative electrode plate (11) further has an extended width portion (112) on one side in the width direction (y-axis direction) intersecting the length direction (x-axis direction) in order to form a tab (111). The solid electrolyte layer (12) is not provided on the extended width portion (112).

[0170] Step 3 (ST3) involves attaching a thin film sheet (14) to a solid electrolyte layer (12) and then removing the carrier film (20). By attaching the thin film sheet (14) to the carrier film (20) and supplying the carrier film (20) in a reel form, the thin film sheet (14) is continuously supplied.

[0171] When the first roll press (31) presses the lower surface of the negative electrode plate (11) and the upper surface of the carrier film (20), the second adhesive (14b) attaches the thin film sheet (14) to the solid electrolyte layer (12) with the required adhesive force. In the third step (ST3), the thin film sheet (14) is initially attached to the solid electrolyte layer (12) with the second adhesive (14b).

[0172] And when the carrier film (20) is separated, the first adhesive (14a) is separated, and the carrier film (20) is separated from the thin film sheet (14). Accordingly, the carrier film (20) is separated and removed from the first adhesive (14a) while the thin film sheet (14) is attached to the solid electrolyte layer (12) via the second adhesive (14b).

[0173] In the third step (ST3), the carrier film (20) is removed after the thin film sheet (14) is attached to the solid electrolyte layer (12), so that the thin film sheet (14) can be more effectively attached to the correct position on the solid electrolyte layer (12).

[0174] FIG. 6 is a plan view of forming a tab by notching a thin film sheet, a solid electrolyte layer, and a negative electrode plate in the manufacturing method of FIG. 3, FIG. 7 is a plan view of the thin film sheet, the solid electrolyte layer, the negative electrode plate, and the tab formed after notching of FIG. 6, and FIG. 8 is a cross-sectional view taken along the line Ⅷ-Ⅷ of FIG. 7.

[0175] Referring to FIG. 1 and FIG. 6 to FIG. 8, the fourth step (ST4) notches the thin film sheet (14), the solid electrolyte layer (12), and the negative electrode plate (11). The fourth step (ST4) notches the outer edges of the thin film sheet (14), the solid electrolyte layer (12), and the negative electrode plate (11) corresponding to the unit cell using a notching punch (41).

[0176] Step 4 (ST4) notches the tab (111) while notching the negative electrode plate (11). Accordingly, the tab (111) protrudes from the negative electrode plate (11) in the width direction (y-axis direction), and the thin film sheet (14) is maintained in an attached state as an additional portion (143) to a portion of the protruding tab (111). The thin film sheet (14) prevents an electrical short circuit between the negative electrode plate (11) and the positive electrode plate (13), and the additional portion (143) further prevents an electrical short circuit between the tab (111) and the positive electrode plate (13).

[0177] In addition, since the thin film sheets (14) are connected, a gap is not formed by the thin film sheets (14) in the plane corresponding to the neighboring unit cells. Accordingly, cracks are prevented from occurring in the active material of the positive electrode plate (13) inserted into the thin film sheet (14), and thus, the possibility of a short circuit occurring can be reduced.

[0178] Fig. 9 is a plan view of the thin film sheet being press-attached to the solid electrolyte layer after the notching of Fig. 6. Referring to Figs. 1, 8, and 9, the fifth step (ST5) press-attaches the thin film sheet (14) to the solid electrolyte layer (12).

[0179] As an example, in step 5 (ST5), a thin film sheet (14) is pressurized and attached to a solid electrolyte layer (12) using a second roll press (51). The thin film sheet (14) is maintained in a firmly attached state to the solid electrolyte layer (12) using a second adhesive (14b).

[0180] Fig. 10 is a plan view of inserting the positive electrode plate onto the solid electrolyte layer inside the thin film sheet after the pressurized attachment of Fig. 9. Referring to Figs. 1, 9, and 10, the sixth step (ST6) inserts the positive electrode plate (13) onto the solid electrolyte layer (12) inside the thin film sheet (14).

[0181] Step 6 (ST6) is to adhere the outer side of the positive electrode plate (13) to the inner side of the thin film sheet (14). Referring to FIG. 13, the outer side of the positive electrode plate (13) is adhered to the inner side of the thin film sheet (14). Since the thin film sheet (14) is provided on the solid electrolyte layer (12), a step structure, i.e., a difference in height between the positive electrode plate (13) and the solid electrolyte layer (12), is not formed. Therefore, cracks are prevented from occurring in the active material of the positive electrode plate (13), and thus, the possibility of a short circuit occurring can be reduced.

[0182] FIG. 11 is a plan view showing a unit cell formed by cutting a thin film sheet, a solid electrolyte layer, and a negative electrode plate after insertion of FIG. 10, FIG. 12 is a plan view of a thin film sheet applied to the unit cell of FIG. 11, and FIG. 13 is a cross-sectional view of an all-solid-state secondary battery unit cell cut along the line ⅩⅢ-ⅩⅢ of FIG. 11. Referring to FIG. 1 and FIGS. 11 to 13, the seventh step (ST7) forms a unit cell (UC) by cutting a thin film sheet (14), a solid electrolyte layer (12), and a negative electrode plate (11).

[0183] Step 7 (ST7) cuts the thin film sheet (14) positioned between adjacent positive electrode plates (13), so that the thin film sheet (14), the solid electrolyte layer (12), and the outer surface of the negative electrode plate (11) form a straight line in the thickness direction. That is, no step is formed on the outer surface, and the positive electrode plate (13) is protected by the thin film sheet (14). Therefore, cracks are prevented from occurring in the active material of the positive electrode plate (13), and thus, the possibility of a short circuit occurring can be reduced.

[0184] The thin film sheet (14) positioned between the positive electrode plates (13) does not form a gap between them. That is, the seventh step (ST7) causes the outer surface of the positive electrode plate (13) and the inner surface of the thin film sheet (14) to be in surface contact with each other. Therefore, the formation of a step between the positive electrode plate (13) and the solid electrolyte layer (12) is prevented. The occurrence of cracks in the active material of the positive electrode plate (13) is prevented, and thus, the possibility of a short circuit can be reduced.

[0185] Step 7 (ST7) cuts a thin film sheet (14) that accommodates a positive electrode plate (13), a solid electrolyte layer (12), and a negative electrode plate (11), thereby forming a unit cell (UC) into a monocell. By stacking unit cells (UC), an all-solid-state secondary battery having a required output can be manufactured.

[0186] Hereinafter, a second embodiment of the present invention will be described. Compared to the first embodiment, descriptions of the same components will be omitted and descriptions of different components will be described. Referring to FIG. 15, in the second embodiment, the thin film sheet (14) includes a first thin film sheet (141) and a second thin film sheet (142), and the carrier film (20) includes a first carrier film (120) and a second carrier film (220). The first step (ST1) attaches the first thin film sheet (141) to the first carrier film (120) (see FIG. 4), and attaches the second thin film sheet (142) to the second carrier film (220) (omitted because it is the same as FIG. 4).

[0187] Fig. 14 is a cross-sectional view of a method for manufacturing an all-solid-state secondary battery according to a second embodiment of the present invention, which supplies a negative electrode plate having first and second solid electrolyte layers on both sides. Referring to Figs. 3 and 14, the second step (ST2') continuously supplies a negative electrode plate (11) having a first solid electrolyte layer (121) and a second solid electrolyte layer (122) on both sides.

[0188] FIG. 15 is a cross-sectional view of the manufacturing method of FIG. 14, in which the first and second thin film sheets attached to the first and second carrier films are attached to the negative electrode plate having the first and second solid electrolyte layers. Referring to FIG. 3 and FIG. 15, the third step (ST3') is a state in which the first thin film sheet (141) and the second thin film sheet (142) are attached to the first solid electrolyte layer (121) and the second solid electrolyte layer (122) provided on both sides of the negative electrode plate (11), respectively.

[0189] Fig. 16 is a cross-sectional view of Fig. 15 with the carrier film removed. Referring to Figs. 3 and 16, in the third step (ST3"), the first thin film sheet (141) and the second thin film sheet (142) are attached to the first solid electrolyte layer (121) and the second solid electrolyte layer (122), respectively, and then the first carrier film (120) and the second carrier film (220) are removed, respectively.

[0190] Fig. 17 is a cross-sectional view of adjacent unit cells cut after inserting the first and second positive electrode plates in Fig. 16 and before cutting the first and second thin film sheets and the first and second solid electrolyte layers and the negative electrode plate.

[0191] Referring to FIG. 3 and FIG. 17, the sixth step (ST6') inserts the first positive electrode plate (131) onto the first solid electrolyte layer (121) inside the first thin film sheet (141) attached to the first solid electrolyte layer (121), and inserts the second positive electrode plate (132) onto the second solid electrolyte layer (122) inside the second thin film sheet (142) attached to the second solid electrolyte layer (122).

[0192] FIG. 18 is a cross-sectional view of a unit cell of an all-solid-state secondary battery after forming and cutting the unit cell of the method for manufacturing an all-solid-state secondary battery according to the second embodiment of the present invention. Referring to FIG. 3 and FIG. 18, the seventh step (ST7') cuts the first thin film sheet (141) positioned between the neighboring first positive electrode plates (131) in the first solid electrolyte layer (121), the negative electrode plate (11), and the second thin film sheet (142) positioned between the neighboring second positive electrode plates (132) in the second solid electrolyte layer (122).

[0193] Therefore, the seventh step (ST7') forms the outer surfaces of the first thin film sheet (141), the first solid electrolyte layer (121), the negative electrode plate (11), the second solid electrolyte layer (122), and the second thin film sheet (142) in a straight line in the thickness direction. That is, no steps are formed on the outer surfaces, and the first and second positive electrode plates (131, 132) are protected by the first and second thin film sheets (141, 142), respectively. Therefore, cracks are prevented from occurring in the active materials of the first and second positive electrode plates (131, 132), and thus, the possibility of a short circuit occurring can be reduced.

[0194] The first thin film sheet (141) positioned between the first positive electrode plates (131) does not form a gap between them. The second thin film sheet (142) positioned between the second positive electrode plates (132) does not form a gap between them. That is, the seventh step (ST7') causes the outer surfaces of the first positive electrode plates (131) and the second positive electrode plates (132) and the inner surfaces of the first thin film sheet (141) and the second thin film sheet (142) to be in surface contact with each other.

[0195] Accordingly, the formation of a step structure, i.e., a step difference, in the height direction of each of the first and second positive electrode plates (131, 132) and the first and second solid electrolyte layers (121, 122) is prevented. The occurrence of cracks in the active material of the first and second positive electrode plates (131, 132) is prevented, and thus, the possibility of a short circuit can be reduced.

[0196] Step 7 (ST7') cuts the first thin film sheet (141) that accommodates the first positive electrode plate (131), the first solid electrolyte layer (121), the negative electrode plate (11), and the second thin film sheet (142) that accommodates the second positive electrode plate (132) and the second solid electrolyte layer (122), thereby forming a unit cell (UC2) as a bi-cell. By stacking the unit cells (UC2), an all-solid-state secondary battery having a required output can be manufactured.

[0197] The above description is only one embodiment for implementing the all-solid-state secondary battery according to the present disclosure, and the present disclosure is not limited to the above-described embodiment, and as claimed in the following claims, it will be understood that the technical spirit of the present disclosure encompasses a range in which various modifications can be implemented without departing from the gist of the present disclosure by anyone having ordinary skill in the art to which the invention pertains.

[0198] - Explanation of symbols -

[0199] 1, 2: All-solid-state secondary battery 11: Negative electrode plate

[0200] 12: Solid electrolyte layer 13: Positive electrode plate

[0201] 14: Thin film sheet 14a: First adhesive

[0202] 14b: Second adhesive 20: Carrier film

[0203] 21: Cover film 31: First roll press

[0204] 41: Notching Punch 111: Tap

[0205] 112: Extended width section 121: First solid electrolyte layer

[0206] 122: Second solid electrolyte layer 131: First positive electrode plate

[0207] 132: Second anode electrode plate 141: First thin film sheet

[0208] 142: Second thin film sheet 143: Additional part

[0209] 120: 1st carrier film 220: 2nd carrier film

[0210] UC: unit cell UC2: unit cell

Claims

1. A first step of attaching a thin film sheet of an irregular reel type to a carrier film; A second step of continuously supplying a cathode electrode plate having a solid electrolyte layer; A third step of removing the carrier film after attaching the thin film sheet to the solid electrolyte layer; A fourth step of notching the thin film sheet, the solid electrolyte layer, and the negative electrode plate; A fifth step of pressurizing and attaching the thin film sheet to the solid electrolyte layer; A sixth step of inserting the positive electrode plate onto the solid electrolyte layer inside the thin film sheet; and Step 7 of forming a unit cell by cutting the above thin film sheet, the solid electrolyte layer, and the negative electrode plate A method for manufacturing an all-solid-state secondary battery comprising:

2. In paragraph 1, The above first step is A method for manufacturing an all-solid-state secondary battery, wherein a cover film is further attached to the inner surface of the carrier film.

3. In paragraph 1, The above first step is The thin film sheet is attached by interposing an adhesive on the outer inner surface of the carrier film, A method for manufacturing an all-solid-state secondary battery, wherein the cover film is separated from the adhesive.

4. In paragraph 1, The above 4th step is A method for manufacturing an all-solid-state secondary battery, comprising notching a tab while notching the negative electrode plate.

5. In paragraph 1, The above 5th step is A method for manufacturing an all-solid-state secondary battery by pressurizing and attaching using a roll press.

6. In paragraph 1, The above 6th step is A method for manufacturing an all-solid-state secondary battery, wherein the outer side of a positive electrode plate is adhered to the inner side of the thin film sheet.

7. In paragraph 1, The above 7th step is By cutting the thin film sheet located between the adjacent positive electrode plates, A method for manufacturing an all-solid-state secondary battery, wherein the outer surfaces of the thin film sheet, the solid electrolyte layer, and the negative electrode plate form a straight line in the thickness direction.

8. In paragraph 7, The above 7th step is A method for manufacturing an all-solid-state secondary battery, wherein the outer surface of the positive electrode plate and the inner surface of the thin film sheet are brought into surface contact with each other.

9. In paragraph 1, The above 7th step is By cutting the thin film sheet that accommodates the positive electrode plate, the solid electrolyte layer, and the negative electrode plate, A method for manufacturing an all-solid-state secondary battery, wherein the above unit cells are formed into a monocell.

10. In paragraph 1, The above thin film sheet includes a first thin film sheet and a second thin film sheet, The above carrier film includes a first carrier film and a second carrier film, The above first step is Attaching the first thin film sheet to the first carrier film and attaching the second thin film sheet to the second carrier film, A method for manufacturing an all-solid-state secondary battery.

11. In paragraph 10, The above solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer, The second step above is A method for manufacturing an all-solid-state secondary battery, which continuously supplies a negative electrode plate having the first solid electrolyte layer and the second solid electrolyte layer on both sides.

12. In paragraph 11, The third step above is A method for manufacturing an all-solid-state secondary battery, wherein the first thin film sheet and the second thin film sheet are respectively attached to the first solid electrolyte layer and the second solid electrolyte layer provided on both sides of the negative electrode plate, and then the first carrier film and the second carrier film are respectively removed.

13. In paragraph 12, The above anode electrode plate includes a first anode electrode plate and a second anode electrode plate, The above 6th step is The first positive electrode plate is inserted into the first solid electrolyte layer inside the first thin film sheet attached to the first solid electrolyte layer, A method for manufacturing an all-solid-state secondary battery, wherein the second positive electrode plate is inserted onto the second solid electrolyte layer inside the second thin film sheet attached to the second solid electrolyte layer.

14. In paragraph 13, The above 7th step is The first thin film sheet positioned between the adjacent first positive electrode plates in the first solid electrolyte layer, The above negative electrode plate, and The second thin film sheet positioned between the adjacent second positive electrode plates in the second solid electrolyte layer By cutting, A method for manufacturing an all-solid-state secondary battery, wherein the first thin film sheet, the first solid electrolyte layer, the negative electrode plate, the second solid electrolyte layer, and the outer surface of the second thin film sheet are formed in a straight line in the thickness direction.

15. In paragraph 14, The above 7th step is A method for manufacturing an all-solid-state secondary battery, wherein the outer surfaces of the first positive electrode plate and the second positive electrode plate and the inner surfaces of the first thin film sheet and the second thin film sheet are brought into surface contact with each other.

16. In paragraph 15, The above 7th step is The first thin film sheet accommodating the first positive electrode plate and the first solid electrolyte layer, The above negative electrode plate, and The second thin film sheet accommodating the second positive electrode plate and the second solid electrolyte layer By cutting it, A method for manufacturing an all-solid-state secondary battery, wherein the above unit cells are formed into bicells.

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