All-solid rechargeable battery

Abstract

An all-solid rechargeable battery is provided. The all-solid secondary battery according to one embodiment comprises: a negative electrode; a solid electrolyte layer stacked on the negative electrode; a positive electrode having a positive electrode active material layer on a positive electrode current collector and stacked on the solid electrolyte layer; an elastic layer provided on at least one side of the positive electrode and the negative electrode; and an insulating frame interposed between the solid electrolyte layer and the positive electrode active material layer.

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 equal areas and electrical short-circuiting is suppressed.

[0007] An all-solid-state secondary battery according to one embodiment 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, an elastic layer provided on at least one side of the positive electrode and the negative electrode, and an insulating frame interposed on the outer surface between the solid electrolyte layer and the positive electrode active material layer.

[0008] The above insulating frame may be an insulating member.

[0009] The pre-compressed thickness (t1) of the above insulation frame is 5㎛ <t1<10㎛ 일 수 있다.

[0010] The thickness (t2) after compression of the above insulating frame is 1㎛ <t2<10㎛ 일 수 있다.

[0011] The thickness (t2) after compression of the above insulating frame is 1㎛ <t2<2.5㎛ 일 수 있다.

[0012] The above insulating frame can be formed by coating a binder on a non-woven fabric.

[0013] The above insulating frame may have a porosity of 5% to 80%.

[0014] The above insulating frame may have a porosity of 50% to 80%.

[0015] The above insulating frame may include an insertion portion having a first width (W1) interposed between the solid electrolyte layer and the positive electrode active material layer, and a non-compressed protrusion portion having a second width (W2) protruding outward from the insertion portion.

[0016] The first width may be 1 mm to 5 mm, and the second width may be 1 mm to 10 mm.

[0017] The above first width may be 2 mm to 5 mm, and the above second width may be 2 mm to 5 mm.

[0018] The above insulating frame can form a compression groove on the positive electrode side and a compression plane on the solid electrolyte layer side.

[0019] The above insulating frame may further include a non-compressible protrusion on the outer surface of the anode and the solid electrolyte layer.

[0020] The above insulating frame can form a compression groove on the solid electrolyte layer side and a compression plane on the anode side.

[0021] The above insulating frame may further include a non-compressible protrusion on the outer surface of the anode and the solid electrolyte layer.

[0022] The above insulating frame can form a first compression groove on the positive electrode side and a second compression groove on the solid electrolyte layer side.

[0023] The above insulating frame may further include a non-compressible protrusion on the outer surface of the anode and the solid electrolyte layer.

[0024] One embodiment can realize uniform pressurization of the solid electrolyte layer through an insulating frame interposed on the outer surface between the solid electrolyte layer and the positive electrode active material layer, even when the areas of the positive and negative electrodes are the same, and suppress electrical short-circuiting between the positive and negative electrodes.

[0025] Figure 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment.

[0026] 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.

[0027] Figure 3 is a longitudinal cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention.

[0028] Figure 4 is a plan view of the all-solid-state secondary battery of Figure 3, with each component laid out.

[0029] Figure 5 is a longitudinal cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention.

[0030] Figure 6 is a cross-sectional view showing an all-solid-state secondary battery according to a third embodiment of the present invention.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] Cathode for all-solid-state secondary batteries

[0036] 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.

[0037] 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, and then drying and rolling.

[0038] 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.

[0039] vanadium oxide

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Fluorine resin binder

[0046] 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.

[0047] 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.

[0048] 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.

[0049] positive electrode active material

[0050] 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.

[0051] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0052] Li a A 1-b Xb O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0053] 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);

[0054] 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);

[0055] 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);

[0056] 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);

[0057] 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);

[0058] 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);

[0059] 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);

[0060] 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);

[0061] 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);

[0062] 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);

[0063] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0064] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0065] Li a Mr 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0066] Li a Mn2G bO4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0067] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0068] QO2; QS2; LiQS2;

[0069] V2O5; LiV2O5;

[0070] LiZO2;

[0071] LiNiVO4;

[0072] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0073] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0074] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0075] 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.

[0076] 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).

[0077] 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.

[0078] [Chemical Formula 1]

[0079] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0080] 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.

[0081] [Chemical Formula 2]

[0082] Li a2 Co x2 M 3 1-x2 O2

[0083] 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.

[0084] [Chemical Formula 3]

[0085] Li a3 Fe x3 M 4 (1-x3) PO4

[0086] 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.

[0087] 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.

[0088] 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.

[0089] Sulfide-based solid electrolyte

[0090] 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.

[0091] 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.

[0092] 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, thereby finely agitating them and mixing 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] Challenge

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] All-solid-state secondary battery

[0105] In one embodiment, an all-solid-state secondary battery is provided, including 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.

[0106] 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.

[0107] cathode

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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 ㎛.

[0133] 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.

[0134] solid electrolyte layer

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] The thickness of the solid electrolyte layer may be, for example, 10 ㎛ to 150 ㎛.

[0141] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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-.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] FIG. 3 is a cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention, and FIG. 4 is a plan view showing the all-solid-state secondary battery of FIG. 3 spread out by each component.

[0152] Referring to FIGS. 3 and 4, the all-solid-state secondary battery (1) of the first embodiment includes a negative electrode (400), a solid electrolyte layer (300), a positive electrode (200), an elastic layer (500), and an insulating frame (10). The all-solid-state secondary battery (1) of the first embodiment is called a mono-cell composed of a single-sided electrode plate.

[0153] The positive electrode (200) of the cross-section has a positive electrode active material layer (203) manufactured by bonding a slurry coating or solvent-free active material to one surface of a positive electrode current collector (201). 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).

[0154] The elastic layer (500) is provided on at least one side of the positive electrode (200) 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 elastic force 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).

[0155] The insulating frame (10) is interposed on the outer surface between the solid electrolyte layer (300) and the positive electrode active material layer (203) to enable uniform pressing of the solid electrolyte layer (300) against the positive electrode (200) 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 (200) during charging are precipitated from the negative electrode (400), and are dissociated and moved to the positive electrode (200) during discharge.

[0156] 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.

[0157] The insulating frame (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 (203). To this end, the insulating frame (10) is made of an insulating material.

[0158] The solid electrolyte layer (300) may be a self-supporting membrane, and in this case, it contains a non-woven fabric inside. That is, the insulating frame (10) may be formed by coating a binder on polypropylene (PP) or polypropylene non-woven fabric.

[0159] As an example, the insulating frame (10) may have a porosity of 5 to 80%. The insulating frame (10) may be formed by coating a binder on a nonwoven fabric having a porosity of 5 to 80%. The insulating frame (10) may have a thickness (t1) greater than 5 μm and less than 10 μm before compression depending on the porosity (5 μm). <t1<10㎛), 압축 후에 1㎛보다 크고 10㎛보다 작은 두께(t2)를 가질 수 있다(1㎛<t2<10㎛).

[0160] The insulating frame (10) is interposed on the outer surface between the solid electrolyte layer (300) and the anode (200) to increase the uniformity of pressing of the solid electrolyte layer (300) through thickness change (t1-t2) before and after compression.

[0161] The insulating frame (10) can be attached to the solid electrolyte layer (300) by heat and pressure. As a result, a laminate of a cathode (400) / solid electrolyte layer (300) / insulating frame (10) can be created. When this laminate is laminated to the anode (200) and pressed using a heated roll press, a laminated cell is created. At this time, the binder in the insulating frame (10) blocks the non-woven fabric holes, thereby limiting the elongation of the elongated insulating frame (10), thereby increasing the uniformity of pressing of the solid electrolyte layer (300).

[0162] Additionally, the insulating frame (10) can be thermally pressed and attached or transferred to the anode (200). This allows a laminate of the anode (200) / insulating frame (10) to be created. This laminate is laminated onto the laminate of the solid electrolyte layer (300) / cathode (400) and pressed using a heated roll press to create a laminated cell.

[0163] The elastic layer (500) is provided on both sides of the laminate of the cathode (400) / solid electrolyte layer (300) / anode (200) and is supported by the end plate (20). The elastic layer (500) is arranged at the outermost part of the laminate and buffers the volume change of the laminate during charging and discharging.

[0164] In the all-solid-state secondary battery (1) of the first embodiment, the area (PA, Positive Electrode Area) of the positive electrode (200) and the area (NA, Negative Electrode Area) of the negative electrode (400) are equal (PA=NA). In other words, the areas into which lithium ions can enter the positive electrode (200) and the negative electrode (400) are equal.

[0165] An insulating frame (10) is placed on the outer edge between the positive electrode (200) and the solid electrolyte layer (300). The insulating frame (10) includes an insertion portion (11) of a first width (W1) interposed between the solid electrolyte layer (300) and the positive electrode active material layer (203), and a non-compressed protrusion portion (12) of a second width (W2) protruding outward from the insertion portion (11).

[0166] In the insulating frame (10), the insertion portion (11) contributes to the uniform pressurization of the solid electrolyte layer (300), and the non-compressed protrusion portion (12) protrudes outward from the anode (200) and the solid electrolyte layer (300) even when the areas of the anode and the cathode are the same, thereby suppressing electrical short-circuiting between the anode (200) and the cathode (400). That is, the area of ​​the cathode (400) (NA, Negative Electrode Area) and the area of ​​the solid electrolyte layer (300) (SA, Solid Electrolyte Area) are the same (NA=SA).

[0167] In this way, the insulating frame (10) is formed as a plate-shaped frame having a combined width (W1+W2) of the first width (W1) and the second width (W2). That is, the insulating frame (10) forms an opening (13) at the inner end of the combined width (W1+W2), and through this opening (13), the solid electrolyte layer (300) and the positive electrode active material layer (203) form a close-contact structure with each other.

[0168] The inner area (IA) of the insulating frame (10) set as the opening (13) is smaller than the area (PA, Positive Electrode Area) of the anode (200) (IA <PA), 양극(200)의 면적(PA)에서 제1폭(W1)의 4배(W1*4)만큼 뺀 크기와 같다(IA=PA-W1*4).

[0169] The outer area (OA) of the insulating frame (10) is larger than the area (PA) of the anode (200) and is equal to the area (PA) of the anode (200) plus four times the second width (W2) (W2*4) (OA=PA+W2*4). For convenience, the inner and outer areas (IA, OA) of the insulating frame (10) and the area (PA) of the anode (200) are considered as rectangles.

[0170] For example, in the insulating frame (10), the first width (W1) is greater than zero and less than 5 mm (0 <W1<5mm). 제1폭(W1)이 5mm보다 크게 되면(W1> 5 mm), a decrease in capacity occurs due to a decrease in the area of ​​the positive electrode active material layer (203).

[0171] In the insulating frame (10), the second width (W2) is greater than zero and less than 10 mm (0 <W2<10mm). 제2폭(W2)이 영이면(W2=0) 절연 프레임(10)이 양극(200)과 음극(400) 사이에서 절연 구조를 형성하지 못하므로 양극(200)과 음극(400) 사이에서 단락이 발생할 수 있다. 제2폭(W2)이 10mm보다 크면(W2> 10mm), the outer size of the cell increases, resulting in a decrease in energy density.

[0172] In the insulating frame (10), the thickness (t1) before pressing is greater than 5㎛ and less than 10㎛ (5㎛ <t1<10㎛). 절연 프레임(10)의 두께(t2)는 압축 후에 1㎛보다 크고 10㎛보다 작다(1㎛<t2<10㎛).

[0173] If the thickness (t1) of the insulation frame (10) before compression is less than 5 ㎛, the pressure is insufficient, making it unsuitable for uniform pressurization of the solid electrolyte layer (300). If the thickness (t2) of the insulation frame (10) after compression is greater than 10 ㎛, the step between the solid electrolyte layer (300) and the insulation frame (10) increases, making it unsuitable for uniform pressurization of the solid electrolyte layer (300).

[0174] The insulating frame (10) forms a compression groove (14) on the anode (200) side and a compression plane (15) on the solid electrolyte layer (300) side. The compression groove (14) and the compression plane (15) enable uniform pressurization of the solid electrolyte layer (300).

[0175] In addition, since the compression groove (14) and the non-compression protrusion (12) surround and protect the edge side of the positive electrode active material layer (203), the positive electrode active material layer (203) can be prevented from being broken.

[0176] In addition, since the non-compressed protrusion (12) protrudes further than the positive electrode (200), even when the areas of the positive electrode (200) and the negative electrode (400) are the same, it protrudes to the outside of the positive electrode (200) and the solid electrolyte layer (300), thereby suppressing electrical short-circuiting between the positive electrode (200) and the negative electrode (400).

[0177] Experimental examples applying the insulation frame (10) of the first embodiment are described. In the first to fifth experimental examples, the porosity of the nonwoven fabric of the insulation frame (10) was changed to 50 to 80%, the first and second widths (W1, W2) of the insulation frame (10) were changed to 2 to 5 mm, and the thickness (t1) of the insulation frame (10) before compression was changed from 5 μm to 1 to 2.5 μm after compression.

[0178] In the first to fourth comparative examples, the porosity of the nonwoven fabric of the insulating frame (10) was changed to 10 to 30%, the first and second widths (W1, W2) of the insulating frame (10) were set to 2 mm, and the thickness (t2) after compression of the insulating frame (10) was changed from 5 ㎛ before compression (t1) to 3.5 to 9 ㎛ after compression. In the fifth comparative example, the insulating frame was not applied.

[0179] Insulation frame (non-woven fabric) Evaluation application Porosity Thickness (㎛) Size (mm) Pressurized initial capacity Short circuit Compression voltage axis After W1W2 Uniformity (mAh / g) Occurrence time 1st experiment example applied 805122 Excellent 195>300 2nd experiment example applied 5052.522 Good 195>300 3rd experiment example applied 5052.552 Good 150>300 4th experiment example applied 5052.525 Good 195>300 5th experiment example applied 5052.555 Good 150>300 1st comparative example applied 3053.522 Suitable 195<250 2nd comparative example applied 205422 Suitable 195<150 3rd comparative example applied 1054.522 Suitable 195<120 4th comparative example applied 1010922 Poor 195<100 5th comparative example not applied----- Excellent 80<1

[0180] In the negative electrode (400), the pre-pressure of the negative electrode active material layer (403) 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. In the positive electrode (400), the specific capacity of the positive electrode active material layer (203) is 200 (mAh / g), the positive electrode active material is 85%, and the L / L (loading level) is 20.56 (mg / cm). 2 ) 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℃.

[0181] The cathode (400) / solid electrolyte layer (300) / anode (200) were welded. The diameter (Ø) 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.

[0182] In the first embodiment, the areas of the cathode (400) and the anode (200) are the same, and the solid electrolyte layer (300), which is a separating layer between the cathode (400) and the anode (200), is uniformly pressurized. As in the first to fifth experimental examples of Table 1, when the areas of the cathode (400) and the anode (300) are the same, the solid electrolyte layer (300) between the cathode and the anode (400, 200) is uniformly pressurized.

[0183] In the first to fourth comparative examples, when the areas of the cathode (400) and the anode (300) are the same, the solid electrolyte layer (300) between the cathode and the anode (400, 200) is pressed with lower uniformity than in the first to fifth experimental examples, where the solid electrolyte layer (300) has a porosity of 50% to 80% according to a porosity of 10% to 30%.

[0184] Furthermore, Comparative Example 5 makes normal charge-discharge evaluation difficult due to a micro-short circuit during the first charge. Therefore, conventional techniques, such as Comparative Example 5, involve introducing a gasket around the anode or applying isostatic pressurization, such as warm-in-place (WIP).

[0185] Experimental examples 1 to 5 applied a single-axis roll press to which a full shear force was applied, and an insulating frame (10) was introduced to the positive electrode (200) surface of the solid electrolyte layer (300) to suppress short circuits compared to comparative examples 1 to 5, and normal charge / discharge and long life were verified.

[0186] Depending on the porosity of the nonwoven fabric forming the insulating frame (10) and the thickness of the nonwoven fabric, the uniformity of pressure, initial capacity, and the time of occurrence of a short circuit were evaluated according to the thickness (t1, t2) before and after compression, and the first and second widths (W1, W2). The thickness (t1) before compression of the insulating frame (10) is 5 μm.

[0187] Experimental examples 1 to 5 confirmed that the porosity of the nonwoven fabric of the insulating frame (10) was 50% to 80% and that the uniformity of the pressure was maintained with the same thickness (t2) of 1 to 2.5 ㎛ after pressure, and that the short-circuit occurrence time was similar at over 300.

[0188] When the porosity of the nonwoven fabric of the insulating frame (10) exceeds 80%, the uniformity of pressing increases, but there is a disadvantage that the nonwoven fabric is not easy to handle. When the porosity of the nonwoven fabric of the insulating frame (10) is lower than 50%, the fabric becomes thicker, which improves handling, but the uniformity of pressing decreases significantly due to the increase in the step of the edge of the positive electrode (200).

[0189] Comparative examples 1 to 4 confirmed that when the first and second widths (W1, W2) of the insulating frame (10) are the same and the porosity of the nonwoven fabric of the insulating frame (10) is 10 to 30%, the short-circuit occurrence time is less than 150 to 250.

[0190] In the first to fifth experimental examples, as the first width (W1) increased, the initial capacity of the positive electrode (200) decreased from 195 mAh / g to 150 mAh / g. On the other hand, when the second width (W2) increased, there was no difference in the basic evaluation, but a decrease in energy density was inevitable.

[0191] Various embodiments of the present invention are described below. Descriptions of identical components are omitted, and descriptions of different components are provided.

[0192] Fig. 5 is a cross-sectional view showing an all-solid-state secondary battery according to a second embodiment of the present invention. Referring to Fig. 5, in the all-solid-state secondary battery (2) of the second embodiment, the insulating frame (20) forms a compression groove (24) on the solid electrolyte layer (300) side and a compression plane (25) on the positive electrode active material layer (203) side of the positive electrode (200). The compression groove (24) and the compression plane (25) enable uniform pressurization of the solid electrolyte layer (300).

[0193] In addition, since the compression groove (24) and the non-compression protrusion (22) surround and protect the edge side of the solid electrolyte layer (300), the solid electrolyte layer (300) can be prevented from being broken.

[0194] In addition, since the non-compressed protrusion (22) protrudes further than the positive electrode (200), even when the areas of the positive electrode (200) and the negative electrode (400) are the same, it protrudes to the outside of the positive electrode (200) and the solid electrolyte layer (300), thereby suppressing electrical short-circuiting between the positive electrode (200) and the negative electrode (400).

[0195] Fig. 6 is a cross-sectional view showing an all-solid-state secondary battery according to a third embodiment of the present invention. Referring to Fig. 6, in the all-solid-state secondary battery (3) of the third embodiment, the insulating frame (30) forms a first compression groove (341) on the positive electrode (200) side and a second compression groove (342) on the solid electrolyte layer (300) side. The first and second compression grooves (341, 342) enable uniform pressurization of the solid electrolyte layer (300).

[0196] In addition, since the first compression groove (341) and the non-compressed protrusion (32) surround and protect the edge side of the positive electrode active material layer (203), the positive electrode active material layer (203) can be prevented from being broken. Since the second compression groove (342) and the non-compressed protrusion (32) surround and protect the edge side of the solid electrolyte layer (300), the solid electrolyte layer (300) can be prevented from being broken.

[0197] 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.

[0198] (Explanation of symbols)

[0199] 1, 2, 3: All-solid-state secondary battery 10, 20, 30: Insulating frame

[0200] 11: Insert 12: Non-compressed protrusion

[0201] 13: Aperture 14: Compression groove

[0202] 15: Compression plane 24: Compression groove

[0203] 25: Compression plane 100: All-solid-state secondary battery

[0204] 200: positive pole 400, 400': negative pole

[0205] 201: Cathode current collector 203: Cathode active material layer

[0206] 300: Solid electrolyte layer 341: First compression groove

[0207] 342: Second compression groove 401: Negative current collector

[0208] 403: Negative active material layer 404: Lithium metal layer

[0209] 405: Cathode coating layer 500: Elastic layer

[0210] IA: Medial area PA: Area of ​​the anode

[0211] OA: outer area t1, t2: thickness

[0212] W1, W2: 1st and 2nd widths

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; An elastic layer provided on at least one side of the positive electrode and the negative electrode; and An insulating frame interposed on the outer surface between the above solid electrolyte layer and the above positive electrode active material layer An all-solid-state secondary battery comprising:

2. In paragraph 1, The above insulating frame is an all-solid-state secondary battery which is an insulating member.

3. In paragraph 1, The pre-compressed thickness (t1) of the above insulation frame is 5㎛ <t1<10㎛ 인 전고체 이차 전지.

4. In paragraph 3, The thickness (t2) after compression of the above insulating frame is 1㎛ <t2<10㎛ 인 전고체 이차 전지.

5. In paragraph 3, The thickness (t2) after compression of the above insulating frame is 1㎛ <t2<2.5㎛ 인 전고체 이차 전지.

6. In paragraph 1, The above insulating frame is an all-solid-state secondary battery formed by coating a binder on non-woven fabric.

7. In paragraph 1, The above insulating frame is an all-solid-state secondary battery having a porosity of 5 to 80%.

8. In paragraph 7, The above insulating frame is an all-solid-state secondary battery having a porosity of 50 to 80%.

9. In paragraph 1, The above insulating frame An insertion portion of a first width (W1) interposed between the solid electrolyte layer and the positive electrode active material layer, and An all-solid-state secondary battery comprising a non-compressible protrusion of a second width (W2) protruding outward from the above insertion portion.

10. In paragraph 9, An all-solid-state secondary battery wherein the first width is 1 mm to 5 mm and the second width is 1 mm to 10 mm.

11. In paragraph 10, An all-solid-state secondary battery wherein the first width is 2 mm to 5 mm and the second width is 2 mm to 5 mm.

12. In paragraph 1, The above insulating frame An all-solid-state secondary battery that forms a compression groove on the positive electrode side and a compression plane on the solid electrolyte layer side.

13. In paragraph 12, An all-solid-state secondary battery wherein the insulating frame further has a non-compressible protrusion on the outer surface of the positive electrode and the solid electrolyte layer.

14. In paragraph 1, An all-solid-state secondary battery in which the insulating frame forms a compression groove on the solid electrolyte layer side and a compression plane on the positive electrode side.

15. In paragraph 14, An all-solid-state secondary battery wherein the insulating frame further has a non-compressible protrusion on the outer surface of the positive electrode and the solid electrolyte layer.

16. In paragraph 1, An all-solid-state secondary battery in which the insulating frame forms a first compression groove on the positive electrode side and a second compression groove on the solid electrolyte layer side.

17. In paragraph 16, An all-solid-state secondary battery wherein the insulating frame further has a non-compressible protrusion on the outer surface of the positive electrode and the solid electrolyte layer.

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