All-solid rechargeable battery

Abstract

Provided is an all-solid rechargeable battery, the all-solid rechargeable battery according to an embodiment comprising: a negative electrode; a solid electrolyte layer laminated on the negative electrode; a positive electrode laminated on the solid electrolyte layer, the positive electrode being provided with a positive active material layer on a positive electrode current collector; and an insulation gasket interposed on the outer edge between the positive active material layer and solid electrolyte layer, wherein the positive active material layer includes a high-density area that corresponds to the gasket and is compressed by the insertion thereof, and a low-density area provided to the inside of the high-density area.

Description

All-solid-state secondary battery

[0001] The present disclosure relates to 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 an all-solid-state secondary battery in which the positive and negative electrodes have the same size and the positive and negative electrode capacitance ratio (NP ratio) of the negative and positive electrodes is greater than 1.0 (NP ratio > 1) to suppress electrical short-circuiting.

[0007] One embodiment provides a method for manufacturing an all-solid-state secondary battery in which the sizes of the positive and negative electrodes are the same and the positive and negative electrode capacitance ratio (NP ratio) of the negative and positive electrodes is greater than 1.0 (NP ratio > 1) to suppress electrical short circuits.

[0008] According to one embodiment, an all-solid-state secondary battery includes a negative electrode, a solid electrolyte layer laminated on the negative electrode, a positive electrode having a positive electrode active material layer on a positive electrode current collector and laminated on the solid electrolyte layer, and an insulating gasket interposed on the outer surface between the positive electrode active material layer and the solid electrolyte layer, wherein the positive electrode active material layer includes a high-density region corresponding to the gasket and compressed by the penetration of the gasket, and a low-density region provided on the inner side of the high-density region.

[0009] The above-mentioned positive electrode collector may include a low-contrast region (smooth surface) corresponding to the high-contrast region, and a high-contrast region (rough surface) provided inside the low-contrast region.

[0010] The first end of the above anode and the above gasket are aligned with each other, and the second end of the solid electrolyte layer can protrude outward by a protrusion width (W) more than the first end.

[0011] The above positive electrode active material layer and the above gasket can form the same plane on the solid electrolyte layer side.

[0012] The above positive electrode active material layer and the gasket can form a step structure.

[0013] The penetration amount of the above gasket may be within 20% of the thickness of the above gasket.

[0014] The above gasket can penetrate into the solid electrolyte layer.

[0015] The above gasket can form a step structure with the positive electrode active material layer and a reverse step structure with the solid electrolyte layer.

[0016] A method for manufacturing an all-solid-state secondary battery according to one embodiment of the present invention includes a first step of pressing a positive electrode having a positive electrode active material layer formed on a positive electrode current collector by a first roll press, a second step of transferring a gasket to an outer surface of the positive electrode active material layer by a second roll press, a third step of pressing the positive electrode having the gasket transferred thereto to form a flat plate, a fourth step of laminating an anode on a solid electrolyte layer, and a fifth step of laminating the solid electrolyte layer on the positive electrode active material layer and the gasket side and pressing it by a third roll press.

[0017] The first step can increase the first adhesive force between the positive electrode active material layer and the gasket to be greater than the second adhesive force between the gasket and the carrier film by pressurizing the positive electrode active material layer by 50% of the total pressurization amount.

[0018] The second step may pressurize a first region corresponding to the gasket among the positive electrode active material layers at a high density, and pressurize a second region set inside the first region at a lower density than the first region.

[0019] The second step may be performed by pressing a first corresponding region corresponding to the first region of the positive electrode current collector with low roughness (relatively smooth surface), and forming a second corresponding region set inside the first corresponding region with high roughness (relatively rough surface) higher than the first corresponding region.

[0020] The fifth step may align the first end of the anode and the gasket with each other, and protrude the second end of the solid electrolyte layer outward by a protrusion width (W) more than the first end.

[0021] The fifth step can form the positive electrode active material layer and the gasket in the same plane on the solid electrolyte layer side.

[0022] In the fifth step, the gasket can be made to protrude further from the surface border of the positive electrode active material on the solid electrolyte layer side and penetrate into the solid electrolyte layer.

[0023] One embodiment can suppress electrical short-circuiting between the positive and negative electrodes while ensuring that the positive and negative electrodes have the same size through a gasket interposed at the edge between the solid electrolyte layer and the positive active material layer.

[0024] Figure 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment.

[0025] 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.

[0026] Figure 3 is a longitudinal cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention.

[0027] Figure 4 is a plan view of the all-solid-state secondary battery of Figure 3, with each component laid out.

[0028] Figure 5 is an enlarged cross-sectional view of a portion of Figure 3.

[0029] Figure 6 is a cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention.

[0030] Figure 7 is a flowchart showing a method for manufacturing an all-solid-state secondary battery according to one embodiment of the present invention.

[0031] Figure 8 is a cross-sectional view of a gasket transferred to the anode without removing the carrier film.

[0032] Figure 9a is a cross-sectional view of a gasket transferred to an anode.

[0033] Figure 9b is a cross-sectional view of the anode transferred in Figure 9a after being struck and the carrier film removed.

[0034] Figure 10 is a cross-sectional view of a state in which a cathode is laminated on a solid electrolyte layer.

[0035] Figure 11 is a cross-sectional view of a state in which a gasket is formed by punching out a transferred anode and stacking it on a solid electrolyte layer.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Cathode for all-solid-state secondary batteries

[0041] 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 a positive electrode active material, a sulfide-based solid electrolyte, a fluorine-based resin binder, and vanadium oxide.

[0042] The above-mentioned positive electrode for an all-solid-state secondary battery is manufactured by applying a positive electrode composition including a positive electrode active material, a sulfide-based solid electrolyte, a fluorine-based resin binder, and vanadium oxide to a current collector, followed by drying and rolling.

[0043] The above-described positive electrode composition generally exhibits strong alkalinity due to residual lithium such as LiOH and other components, which may result in gelation or aggregation of the fluorine-based resin binder. However, according to one embodiment, the addition of vanadium oxide suppresses gelation of the fluorine-based resin binder, thereby maintaining the viscosity of the positive electrode composition and ensuring processability. Furthermore, since there is no need for a neutralizing agent, deterioration of the sulfide-based solid electrolyte caused by the neutralizing agent can be prevented, thereby improving the performance of the all-solid-state secondary battery.

[0044] vanadium oxide

[0045] The above vanadium oxide is a component that does not dissolve in the solvent of the positive electrode composition, and can control the strong basicity of the positive electrode composition to prevent gelation of the fluorine-based resin binder, while simultaneously suppressing deterioration of the sulfide-based solid electrolyte, thereby improving the ionic conductivity of the positive electrode. It is understood that vanadium oxide controls the pH through physical and / or chemical reactions with the -OH group in the positive electrode composition in a strongly basic state, thereby suppressing gelation of the fluorine-based resin binder. The vanadium oxide has a more excellent ability to suppress gelation of the fluorine-based resin binder by controlling basicity than other transition metal oxides such as titanium oxide or tungsten oxide, has low reactivity with the sulfide-based solid electrolyte, and suppresses deterioration of the sulfide-based solid electrolyte, thereby improving the ionic conductivity of the all-solid-state secondary battery and enhancing the overall performance.

[0046] The above vanadium oxides include, for example, V2O3, VO2, V2O4, V2O 5,Or a combination thereof may be included. In addition, the vanadium oxide may be included in an amount of 0.01 wt% to 5 wt% based on 100 wt% of the positive electrode active material layer, for example, 0.05 wt% to 5 wt%, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 0.5 wt% to 3 wt%. When the vanadium oxide is included in such an amount, the viscosity of the positive electrode composition can be appropriately maintained without a decrease in capacity, thereby improving processability and enhancing the ionic conductivity of the positive electrode.

[0047] According to one embodiment, since vanadium oxide is added to the positive electrode composition and dispersed therein, the positive electrode composition is coated on the current collector, so the vanadium oxide may be dispersed within the manufactured positive electrode active material layer. This is distinct from a form in which vanadium oxide is coated on the surface of the positive electrode active material or the sulfide-based solid electrolyte.

[0048] In one example, the vanadium oxide may be pentavalent vanadium oxide (vanadium(V) oxide), in which case the melting point of the vanadium oxide may be 1000°C or lower, for example, 600°C to 800°C, or 650°C to 690°C. The pentavalent vanadium oxide is excellent in suppressing gelation of a fluorine-based resin binder in the positive electrode and is advantageous in improving the overall performance of the battery.

[0049] In addition, the vanadium oxide may be in the form of particles, and the average particle diameter (D50) may be 10 nm to 10 ㎛, for example, 10 nm to 5 ㎛, 10 nm to 3 ㎛, 50 nm to 1 ㎛, 50 nm to 500 nm, or 500 nm to 1 ㎛. Vanadium oxide having such properties is suitable for incorporation into a positive electrode composition, and can effectively suppress gelation of the positive electrode composition without adversely affecting the positive electrode. If the particle diameter of the vanadium oxide is too small, it may not be properly dispersed within the positive electrode, thereby blocking the movement path of electrons and ions, thereby deteriorating battery performance, or may not sufficiently perform its role of suppressing gelation of the binder. On the contrary, if the particle diameter of the vanadium oxide is too large, it itself may block the movement path of electrons and ions, thereby deteriorating battery performance.

[0050] Fluorine resin binder

[0051] The above fluorine-based resin binder may be a general resin binder containing fluorine, and may include, for example, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polytetrafluoroethylene, or a combination thereof.

[0052] The weight average molecular weight of the fluorinated resin binder may be approximately 50 kDa to 5,000 kDa, or 100 kDa to 2,000 kDa. In addition, the glass transition temperature of the fluorinated resin binder may be -10°C or lower, and the melting point may be 100°C or higher. The melting viscosity of the fluorinated resin binder may be approximately 10 kP to 50 kP. In addition, the fluorinated resin binder may be in the form of particles, and the average particle diameter thereof may be approximately 50 nm to 200 μm. The fluorinated resin binder having such properties can implement excellent adhesive strength even when added in a small amount to the positive electrode composition, and can increase the durability of the battery without adversely affecting the battery performance.

[0053] The fluorine-based resin binder may be included in an amount of 0.1 wt% to 10 wt% based on 100 wt% of the positive electrode active material layer, for example, 0.1 wt% to 8 wt%, 0.1 wt% to 6 wt%, 0.1 wt% to 5 wt%, 0.5 wt% to 4 wt%, or 1 wt% to 3 wt%. When the fluorine-based resin binder is included in the above content range, it can exhibit excellent adhesive strength without adversely affecting the positive electrode.

[0054] positive electrode active material

[0055] 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.

[0056] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0057] Li a A 1-b Xb O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0058] 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);

[0059] 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);

[0060] 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);

[0061] 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);

[0062] 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);

[0063] 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);

[0064] Li a Ni 1-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);

[0065] 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);

[0066] 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);

[0067] 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);

[0068] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0069] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0070] Li a Mr 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0071] Li a Mn2G bO4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0072] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0073] QO2; QS2; LiQS2;

[0074] V2O5; LiV2O5;

[0075] LiZO2;

[0076] LiNiVO4;

[0077] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0078] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0079] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0080] 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.

[0081] 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).

[0082] 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.

[0083] [Chemical Formula 1]

[0084] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0085] 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.

[0086] [Chemical Formula 2]

[0087] Li a2 Co x2 M 3 1-x2 O2

[0088] 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.

[0089] [Chemical Formula 3]

[0090] Li a3 Fe x3 M 4 (1-x3) PO4

[0091] 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.

[0092] 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.

[0093] 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.

[0094] Sulfide-based solid electrolyte

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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 Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I) and can be expressed by the chemical formula, 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.

[0099] 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 an electrode layer and a 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] Challenge

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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 yTiO3, 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.

[0109] All-solid-state secondary battery

[0110] 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.

[0111] 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 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 collector (201) are laminated is housed in a case such as a pouch. The all-solid-state 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.

[0112] cathode

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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 ㎛.

[0138] 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.

[0139] solid electrolyte layer

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] The thickness of the solid electrolyte layer may be, for example, 10 ㎛ to 150 ㎛.

[0146] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0147] 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.

[0148] The 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.

[0149] 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.

[0150] 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.

[0151] 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-.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] FIG. 3 is a cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention, FIG. 4 is a plan view showing the all-solid-state secondary battery of FIG. 3 spread out by component, and FIG. 5 is a cross-sectional view showing an enlarged portion of a part of FIG. 3.

[0157] Referring to FIGS. 3 to 5, the all-solid-state secondary battery (1) of the first embodiment includes a negative electrode (400), a solid electrolyte layer (300), a positive electrode (210), an elastic layer (500), and an insulating gasket (10). The all-solid-state secondary battery (1) of the first embodiment is referred to as a mono-cell composed of a single-sided electrode plate. Although not separately illustrated, the gasket (10) can also be applied in the same structure to a bi-cell.

[0158] The positive electrode (210) of the cross-section has a positive electrode active material layer (213) manufactured by bonding a slurry coating or solvent-free active material to one surface of a positive electrode current collector (211). The negative electrode (400) has a negative electrode active material layer (403) on a negative electrode current collector (401). The solid electrolyte layer (300) can be formed as a film by directly coating a solid electrolyte film on the negative electrode active material layer (403).

[0159] The elastic layer (500) is provided on at least one side of the positive electrode (210) and the negative electrode (400), and in the present embodiment, on both sides. The elastic layer (500) provides flatness between the negative electrode (400) and the solid electrolyte layer (300) with buffering force and elasticity in response to Li precipitation and dissociation of the negative electrode (400) during charging and discharging, and provides flatness between the solid electrolyte layer (300) and the positive electrode (200).

[0160] A gasket (10) is interposed at the edge between the positive electrode active material layer (213) and the solid electrolyte layer (300) to enable uniform pressing of the solid electrolyte layer (300) against the positive electrode (210) and the negative electrode (400). When the negative electrode (400) is of the Li ion precipitation type, Li ions that pass through the solid electrolyte layer (300) from the positive electrode (210) during charging are precipitated at the negative electrode (400), and are dissociated and moved to the positive electrode (210) during discharge.

[0161] During charging, Li ions are precipitated from the negative electrode (400), and the cell volume expands. In addition, if no pressure is applied to the cell, the Li ion precipitation becomes uneven in a free state, and as charging and discharging proceed, the unevenness of the lithium ion precipitation is amplified, which may partially break the solid electrolyte layer (300), leading to a short circuit.

[0162] The gasket (10) is configured to enable uniform pressurization of the solid electrolyte layer (300) while preventing the movement of lithium ions from the outer surface of the positive electrode active material layer (213). To this end, the gasket (10) has zero ionic conductivity.

[0163] The solid electrolyte layer (300) may be a self-supporting membrane, in which case it contains a non-woven fabric inside. That is, the gasket (10) may be formed by coating a binder on polypropylene (PP) or polypropylene non-woven fabric.

[0164] A gasket (10) is interposed on the outer surface between the solid electrolyte layer (300) and the anode (210), so as to increase the uniformity of pressurization of the solid electrolyte layer (300) through changes in the thickness, density, and roughness of the anode (210) during the pressurization process. The gasket (10) can be formed of an oxide and has a set thickness (t) and width (W1).

[0165] The change in the thickness of the positive electrode (210) due to the pressurizing process appears in the positive electrode active material layer (213). By the pressurizing process, the positive electrode active material layer (213) includes a high density area (HDA) and a low density area (LDA) by the gasket (10). As an example, the high density area (HDA) has a density of 3.4 to 3.6 g / cm. 3 , and the low density area (LDA) has a density of 3.2–3.4 g / cm 3 can be displayed as

[0166] The high-density area (HDA) corresponds to the width (W1) of the gasket (10) and is compressed with an indentation corresponding to the thickness (t) of the gasket (10). The low-density area (LDA) is provided on the inside of the high-density area (HDA) and does not correspond to the width (W1) of the gasket (10). That is, the high-density area (HDA) and the low-density area (LDA) are set corresponding to the boundary line by the width (W1) of the gasket (10).

[0167] In addition, the change in the thickness of the positive electrode (210) due to the pressurizing process is expressed as a change in the intensity of the positive electrode current collector (211). Due to the pressurizing process, the positive electrode current collector (211) includes a low intensity area (LIA) and a high intensity area (HIA) by the gasket (10). As an example, the low intensity area (LIA) may be expressed as 800 to 1500 nm, and the high intensity area (HIA) may be expressed as 150 to 800 nm.

[0168] The low-roughness area (LIA) forms a smooth surface corresponding to the width (W1) of the gasket (10), i.e., the high-density area (HDA). The high-roughness area (HIA) forms a rough surface corresponding to the outside of the width (W1) of the gasket (10), i.e., the low-density area (LDA), and is provided on the inside of the low-roughness area (LIA).

[0169] The first end (E1) of the anode (210) and the gasket (10) are aligned with each other, and the second end (E2) of the solid electrolyte layer (300) protrudes outward by a protrusion width (W2) more than the first end (E1). At this time, the anode (210) and the cathode (400) have the same size.

[0170] The solid electrolyte layer (300) is the same size as the cathode (400) before the pressurizing process, and becomes larger than the cathode (400) due to stretching after the pressurizing process. That is, the solid electrolyte layer (300) becomes larger on one side by the protrusion width (W2) than the cathode (400), and therefore, when considering both sides of the total width, it becomes twice as large (W2*2).

[0171] The gasket (10) is formed of a thin oxide layer and may have a width (W1) and a thickness (t) of the gasket (10). For example, the width (W1) is greater than 0 and less than 5 mm (0 <W1<5 mm). 두께(t)는 0보다 크고 10㎛보다 작다(0<t<10㎛).

[0172] If the width (W1) of the gasket (10) is zero (W1=0), an insulating layer cannot be formed on the positive electrode (210), and if the width (W1) of the gasket (10) is greater than 5 mm (W1>5 mm), the performance of the positive electrode active material layer (213) may be reduced, resulting in a decrease in capacity. In addition, if the thickness (t) of the gasket (10) is 10 μm or more, a step is created too large on the positive electrode active material layer (213), making it unsuitable for uniform pressurization of the solid electrolyte layer (300).

[0173] Compared to the negative electrode (400), the protrusion (W2) of the solid electrolyte layer (300) is zero (W2=0) before the pressing process, and is 1 mm or less (0≤W2≤1mm) as it protrudes due to lateral stretching during the roll press pressing process. Due to the protrusion (W2) of the solid electrolyte layer (300), physical contact between the negative electrode (400) and the positive electrode (210) can be suppressed. The protrusion (W2) is derived from the pressing process and is therefore not easily broken or dropped.

[0174] In this way, while the sizes of the anode (210) and cathode (400) are the same, the functional anode-cathode capacity ratio (NP ratio) of the cathode (400) and the anode (200) becomes greater than 1.0 (NP ratio>1) due to the protrusion width (W2) of the gasket (10). As a result, electrical short-circuiting between the cathode (400) and the anode (200) can be suppressed.

[0175] Due to the penetration of the gasket (10), the positive electrode active material layer (213) and the gasket (10) form the same plane on the solid electrolyte layer (300) side. The all-solid positive electrode active material layer (213) and the gasket (10) form a step structure.

[0176] Therefore, even when a gasket (10) is applied, the pressure between the solid electrolyte layer (300) where the gasket (10) is positioned and the positive electrode active material layer (213) and the pressure between the solid electrolyte layer (300) where the gasket (10) is not positioned and the gasket (10) can be balanced.

[0177] Fig. 6 is a cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention. Referring to Fig. 6, in the all-solid-state secondary battery (2) of the second embodiment, a gasket (20) is interposed on the outer surface between the solid electrolyte layer (300) and the positive electrode (220), thereby increasing the uniformity of pressing of the solid electrolyte layer (320) through changes in thickness, density, and roughness of the positive electrode (220) and the solid electrolyte layer (320) during the pressing process.

[0178] The positive electrode (220) includes a positive electrode current collector (221) and a positive electrode active material layer (223). The gasket (20) can penetrate into the positive electrode active material layer (223) and the solid electrolyte layer (320). At this time, the penetration amount (D1) of the gasket (20) into the solid electrolyte layer (320) can be within 20% of the thickness (t) of the gasket (20) (D1≤0.2t). The gasket (20) forms a step structure with the positive electrode active material layer (223) and a reverse step structure with the solid electrolyte layer (320).

[0179] Therefore, even when a gasket (20) is applied, the pressure between the solid electrolyte layer (320) where the gasket (20) is positioned and the positive electrode active material layer (223) and the pressure between the solid electrolyte layer (320) where the gasket (20) is not positioned and the gasket (20) can be balanced.

[0180] Figure 7 is a flowchart illustrating a method for manufacturing an all-solid-state secondary battery according to one embodiment of the present invention. For convenience, the all-solid-state secondary battery (1) of the first embodiment will be described as an example.

[0181] Referring to Fig. 7, a method for manufacturing an all-solid-state secondary battery of one embodiment includes a first step (ST1), a second step (ST2), a third step (ST3), a fourth step (ST4), and a fifth step (ST5). In the first step (ST1), a positive electrode (210) having a positive electrode active material layer (213) formed on a positive electrode current collector (211) is pressed using a first roll press.

[0182] Fig. 8 is a cross-sectional view showing a gasket transferred to the positive electrode without removing the carrier film. Referring to Figs. 7 and 8, the gasket (10) is handled in a state of being adhered to the carrier film (11), and is supplied to the positive electrode active material layer (213) together with the carrier film (11), and then transferred.

[0183] Step 1 (ST1) pressurizes the positive electrode active material layer (213) by 50% of the total process pressure for the positive electrode active material layer (213). At this time, the first adhesive force formed between the positive electrode active material layer (213) and the gasket (10) increases to a greater degree than the second adhesive force formed between the gasket (10) and the carrier film (11).

[0184] Fig. 9a is a cross-sectional view of a state in which a gasket is transferred to a positive electrode, and Fig. 9b is a cross-sectional view of a state in which the positive electrode transferred in Fig. 9a is punched out and the carrier film is removed. Referring to Fig. 7 and Fig. 9a, in the second step (ST2), a gasket (10) is transferred to the outer surface of the positive electrode active material layer (213) by applying pressure with a second roll press.

[0185] In the second step (ST2), the first region (AR1) corresponding to the gasket (10) among the positive electrode active material layers (213) is pressed into a high-density region (HDA), and the second region (AR2) set inside the first region (AR1) is pressed into a low-density region (LDA) lower than the first region (AR1).

[0186] In addition, the second stage (ST2) pressurizes the first response area (RA1, response area) corresponding to the first area (AR1) of the positive electrode collector (211) to a low-irradiance area (smooth surface) (LIA), and pressurizes the second response area (RA2) set inside the first response area (RA1) to a high-irradiance area (rough surface) (HIA) higher than the first response area (RA1).

[0187] Referring to FIGS. 7 and 9b, the third step (ST3) pressurizes and stamps out the positive electrode (210) onto which the gasket (10) has been transferred. In the stamped positive electrode (210), the positive electrode active material layer (213) includes a first region (AR1) and a second region (AR2), and the positive electrode current collector (211) includes a first corresponding region (RA1) and a second corresponding region (RA2).

[0188] Fig. 10 is a cross-sectional view of a state in which a cathode is laminated on a solid electrolyte layer. Referring to Figs. 7 and 10, in step 5 (ST5), a cathode (400) is laminated on a solid electrolyte layer (300). A laminate of the solid electrolyte layer (300) and the cathode (400) is formed. At this time, the outer surfaces of the solid electrolyte layer (300) and the cathode (400) remain aligned.

[0189] Figure 11 is a cross-sectional view of a state in which a positive electrode with a gasket transferred is pressed and laminated on a solid electrolyte layer. Referring to Figures 7 and 11, in the fifth step (ST5), a solid electrolyte layer (300) is laminated on the positive electrode active material layer (213) and the gasket (10) side and pressed using a third roll press. At this time, the solid electrolyte layer (300) is elongated and protrudes further to one side than the negative electrode (400) by a protrusion width (W2).

[0190] That is, through the pressurization process, the fifth step (ST5) aligns the first end (E1) of the anode (210) and the gasket (10) with each other, and protrudes the second end (E2) of the solid electrolyte layer (300) outward by a protrusion width (W) more than the first end (E1).

[0191] In the fifth step (ST5), the gasket (10) penetrates into the positive electrode active material layer (213), and the positive electrode active material layer (213) and the gasket (10) are formed on the same plane on the solid electrolyte layer (300) side (see FIG. 5 and FIG. 11).

[0192] Therefore, even when a gasket (10) is applied, the pressure between the solid electrolyte layer (300) where the gasket (10) is positioned and the positive electrode active material layer (213) and the pressure between the solid electrolyte layer (300) where the gasket (10) is not positioned and the gasket (10) can be balanced.

[0193] When applying the all-solid-state secondary battery (2) of the second embodiment, in the fifth step (ST5), the gasket (20) penetrates into the positive electrode active material layer (223), and on the solid electrolyte layer (320) side, the gasket (20) protrudes further beyond the surface border of the positive electrode active material (223) and penetrates into the solid electrolyte layer (320) (see FIG. 6).

[0194] Therefore, even when a gasket (20) is applied, the pressure between the solid electrolyte layer (320) where the gasket (20) is positioned and the positive electrode active material layer (223) and the pressure between the solid electrolyte layer (320) where the gasket (20) is not positioned and the gasket (20) can be balanced.

[0195] Referring to Table 1 below, actual experimental examples and comparative examples manufactured using the all-solid-state secondary battery manufacturing method of the embodiment are compared and explained.

[0196] Gasket evaluation application Partial binder thickness (㎛) Width (W1) (mm) Pressurization uniformity Initial capacity (mAh / g) Short circuit occurrence time Composition Size (D50, ㎛) PVDF-HFP (wt.%) 1st experiment example Application Al2O3 0.35 12⊙181>300 2nd experiment example Application SiO2 0.35 12⊙180>300 3rd experiment example Application ZrO2 0.35 12⊙182>300 4th experiment example Application TiO2 0.35 12⊙179>300 5th experiment example Application Al2O3 0.35 2 2⊙181>300 6th experiment example Experimental example application Al2O30.350.52⊙170>300 Experimental example 7 application Al2O30.3532○165<200 Experimental example 8 application Al2O30.3521⊙190<200 Experimental example 9 application Al2O30.3520.5⊙195<100 Experimental example 1 application Not applied-----⊙200>300 Experimental example 2 application Not applied-----⊙80<1

[0197] ⊙ Excellent, ○ Good

[0198] The pre-pressure of the negative electrode active material layer (403) in the negative electrode (400) is 1.5 (ton.f / cm) in line pressure, and RT (room temperature) is 25°C. The solid electrolyte layer (300) is directly coated on the negative electrode active material layer (403) and dried to have a thickness of 100 μm.

[0199] The specific capacity of the positive electrode active material layer (213) in the positive electrode (210) is 200 (mAh / g), the positive electrode active material is 85%, and the L / L (loading level) is 20.56 (mg / cm2 ) and the current density is 4.11 (mAh / cm 2 ), and when pre-pressurized, the line pressure is 5.0 (ton.f / cm) and the temperature is 120℃.

[0200] The cathode (400) / solid electrolyte layer (300) / anode (210) were welded. The diameter (f) of the two rolls of the roll press was 400x400mm, the effective length was 120mm, the line pressure was 5.0 (tonf / cm), and the temperature was 120°C. The elastic layer (500) was made of acrylic foam or polyurethane foam with a thickness of 300 (㎛), and was applied to the charge / discharge evaluation. The initial capacity was 0.1C-0.05C charge and 0.1C discharge, and the short-circuit occurrence time was 0.33C-0.1C charge and 0.33C discharge.

[0201] Experimental examples 1 to 9 were pressurized using a roll press, and comparative example 1 applied isostatic pressurization (500 MPa, 98°C, 30 min) similar to warm isostatic pressurization (WIP) using a gasket. Comparative example 2 was pressurized under the same conditions as the roll press. In comparative example 2, normal charge / discharge evaluation was difficult due to a micro-short circuit during the first charge.

[0202] In the first to ninth experimental examples, the sizes of the positive electrode (210) and the negative electrode (400) are the same, so the positive electrode capacity ratio (NP ratio) is set to 1.0, and the solid electrolyte layer (300), which is the separation layer of the negative electrode (210) and the positive electrode (400), can be uniformly pressurized.

[0203] Experimental examples 1 to 9 applied a single-axis roll press to which shear force was applied, and a gasket (10) was applied to the edge of the positive electrode (210) to verify normal charging and discharging and long life. Experimental examples 1 to 9 suppressed short circuits similar to comparative example 2.

[0204] The gasket (10) is composed of oxide powder and a binder. As an example, the powder size is 300 nm, and 5 wt.% of PVDF-HFP, which has low reactivity with sulfide-based electrolytes, is applied as the binder. The thickness (t) of the gasket (10) is 0.5 to 10 ㎛, and the width (W1) is adjusted in the range of 0.5 to 2 mm.

[0205] And the evaluation criteria for each condition are the uniformity of pressurization of the solid electrolyte layer (300), the initial capacity during charge and discharge, and the time of occurrence of a short circuit during the lifespan.

[0206] Experimental examples 1 to 4 changed the powder composition of the gasket (10), but equivalent characteristics were confirmed in terms of pressurization uniformity and short-circuit occurrence time (i.e., insulation characteristics). Experimental examples 5 to 7 changed the thickness (t) of the gasket (10), and here, as the thickness (t) increased, pressurization uniformity worsened, and also the initial capacity and lifespan deteriorated compared to the reference.

[0207] In the 8th and 9th experimental examples, the width (W1) of the gasket (10) was reduced, and although the initial capacity increased as the width (W1) decreased, the lifespan, on the contrary, worsened compared to the reference. In other words, it was found that as the width (W1) of the gasket (10) decreases, the amount of Li precipitation at the edge of the negative electrode (4100) increases, and also the stress of Li toward the solid electrolyte layer (300) increases, shortening the short-circuit time.

[0208] In general, if the sizes of the anode and cathode are not identical, it is impossible to uniformly pressurize the intermediate solid electrolyte layer using a uniaxial pressurization method. Furthermore, if the sizes of the anode and cathode are identical, there is a problem of short-circuiting due to excessive lithium precipitation and lithium ion migration at the cathode edge.

[0209] However, in the experimental examples of the present invention, even when the positive electrode capacity ratio (NP ratio) is 1.0, a gasket (10) is applied between the positive electrode (210) and the solid electrolyte layer (300), so that a short circuit does not occur even with a single-axis roll press, and the solid electrolyte layer (300) can be uniformly pressed.

[0210] The above description is only one embodiment for implementing the method for manufacturing an all-solid-state battery, the process plate, and the all-solid-state 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 present invention pertains.

[0211] - Explanation of symbols -

[0212] 1, 2: All-solid-state secondary battery 10, 20: Gasket

[0213] 210, 220: Anode 211, 221: Anode current collector

[0214] 213, 223: Cathode active material layer 300, 320: Solid electrolyte layer

[0215] 400: Cathode 401: Cathode current collector

[0216] 403: Negative active material layer 500: Elastic layer

[0217] AR1: Area 1 AR2: Area 2

[0218] D1: Intrusion amount E1: First end

[0219] E2: Second stage HAD: High density area

[0220] HIA: High intensity area LDA: Low density area

[0221] LIA: Low-Intensity Area RA1: First Response Area

[0222] RA2: Second response area t: Thickness

[0223] W1: Width W2: Projection width

Claims

1. Cathode; A solid electrolyte layer laminated on the above cathode; A cathode having a cathode active material layer on a cathode current collector and laminated on the solid electrolyte layer; and It includes an insulating gasket interposed on the outer surface between the positive electrode active material layer and the solid electrolyte layer, The above positive electrode active material layer A high-density region corresponding to the above gasket and compressed by the penetration of the above gasket, and A low-density region provided inside the above high-density region An all-solid-state secondary battery comprising:

2. In paragraph 1, The above positive electrode current collector A low-light area corresponding to the high-density area, and A high-light area provided inside the above low-light area An all-solid-state secondary battery comprising:

3. In paragraph 2, The first end of the above anode and the above gasket are coincident with each other, An all-solid-state secondary battery in which the second end of the above-mentioned solid electrolyte layer protrudes outward by a protrusion width (W) more than the first end.

4. In paragraph 2, An all-solid-state secondary battery in which the positive electrode active material layer and the gasket form the same plane on the solid electrolyte layer side.

5. In paragraph 4, An all-solid-state secondary battery in which the positive electrode active material layer and the gasket form a step structure.

6. In paragraph 1, An all-solid-state secondary battery wherein the penetration amount of the above gasket is within 20% of the thickness of the above gasket.

7. In paragraph 1, The above gasket An all-solid-state secondary battery that penetrates into the above solid electrolyte layer.

8. In paragraph 7, The above gasket Forming a step structure with the above positive electrode active material layer, An all-solid-state secondary battery forming a reverse step structure with the above solid electrolyte layer.

9. The first step of pressing the positive electrode, which has a positive electrode active material layer formed on the positive electrode current collector, using a first roll press; A second step of transferring a gasket to the outer surface of the positive electrode active material layer by applying pressure to a second roll press; A third step of pressing and punching the anode to which the gasket has been transferred; A fourth step of laminating a cathode on a solid electrolyte layer; and Step 5 of laminating the solid electrolyte layer on the positive electrode active material layer and the gasket side and applying pressure through a third roll press A method for manufacturing an all-solid-state secondary battery comprising:

10. In paragraph 9, The above first step is By pressurizing the positive electrode active material layer by 50% of the total pressurization amount, A method for manufacturing an all-solid-state secondary battery, wherein the first adhesive strength of the positive electrode active material layer and the gasket is increased to a greater extent than the second adhesive strength of the gasket and the carrier film.

11. In paragraph 9, The above second step is Among the above positive electrode active material layers, the first region corresponding to the gasket is pressurized at high density, A method for manufacturing an all-solid-state secondary battery, wherein a second region set inside the first region is pressurized to a lower density than the first region.

12. In paragraph 11, The above second step is The first corresponding region corresponding to the first region among the above-mentioned positive electrode collectors is pressurized at low light, A method for manufacturing an all-solid-state secondary battery, wherein the second response area, which is set inside the first response area, is formed at a higher luminosity than the first response area.

13. In paragraph 12, The above 5th step is Align the first end of the above anode and the above gasket with each other, A method for manufacturing an all-solid-state secondary battery in which the second end of the above-mentioned solid electrolyte layer protrudes outward by a protrusion width (W) more than the first end.

14. In paragraph 12, The above 5th step is A method for manufacturing an all-solid-state secondary battery, wherein the positive electrode active material layer and the gasket are formed in the same plane on the solid electrolyte layer side.

15. In paragraph 14, The above 5th step is A method for manufacturing an all-solid-state battery in which the gasket protrudes further from the surface border of the positive electrode active material and penetrates into the solid electrolyte layer on the solid electrolyte layer side.

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