All-solid rechargeable battery

Abstract

Provided is an all-solid rechargeable battery, the all-solid rechargeable battery according to one embodiment comprising: a negative electrode; a first solid electrolyte layer provided on one surface of the negative electrode; a second solid electrolyte layer provided on one surface of the first solid electrolyte layer; and a positive electrode provided on one surface of the second solid electrolyte layer, wherein the first solid electrolyte layer contains round-type first solid electrolyte particles and has a first thickness of 2µm or less.

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 a first solid electrolyte layer and a second solid electrolyte layer provided on both sides between a cathode and an anode are formed differently from each other.

[0007] According to one embodiment, an all-solid-state secondary battery includes an anode, a first solid electrolyte layer provided on one surface of the anode, a second solid electrolyte layer provided on one surface of the first solid electrolyte layer, and a cathode provided on one surface of the second solid electrolyte layer, wherein the first solid electrolyte layer includes round-type first solid electrolyte particles and is formed to have a first thickness of 2 μm or less.

[0008] The above first solid electrolyte particles can be formed into one of a spherical, oval, and disc shape.

[0009] The second solid electrolyte layer includes second solid electrolyte particles, and the second solid electrolyte particles can be formed in a sharp type.

[0010] The first solid electrolyte layer may include first solid electrolyte particles in the form of a powder manufactured by a wet process.

[0011] The second solid electrolyte layer may include second solid electrolyte particles in the form of powder manufactured by a dry process.

[0012] The second solid electrolyte layer includes second solid electrolyte particles, and the second solid electrolyte particles may have a second thickness of 3 μm to 5 μm.

[0013] The above first solid electrolyte particles may have a first thickness of 0.5 μm to 1 μm.

[0014] The above first solid electrolyte particles are formed with an average particle diameter (D50) of 10 nm to 10 ㎛, and the first solid electrolyte layer can form a first thickness of 50 ㎛ to 100 ㎛ before pressurization.

[0015] The second solid electrolyte layer includes second solid electrolyte particles, and the second solid electrolyte particles have an average particle diameter (D50) of 10 nm to 10 μm, and the second solid electrolyte layer can form a second thickness of 250 μm to 50 μm before pressurization.

[0016] The first solid electrolyte layer may be formed with a first thickness (t1'), and the second solid electrolyte layer may be formed with a second thickness (t2') greater than the first thickness (t2'>t1').

[0017] One embodiment includes placing first solid electrolyte particles, which are wet-manufactured and consist of smooth, round, and fine particles on the cathode side, and placing second solid electrolyte particles, which are dry-manufactured and consist of rough, sharp, and large particles on the anode side.

[0018] One embodiment reduces the amount of dry-manufactured, rough-surfaced second solid electrolyte particles that improve battery performance while partially using wet-manufactured, smooth-surfaced first solid electrolyte particles that have somewhat lower performance, thereby preventing damage to the negative electrode and reducing physical defects within the cell while maintaining the performance of the all-solid-state secondary battery.

[0019] In this way, one embodiment can improve short circuits due to reduced cathode breakage and physical defects.

[0020] Figure 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment.

[0021] 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.

[0022] Figure 3 is a longitudinal cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention.

[0023] Figure 4 is a cross-sectional view showing the pre-pressurization state of the all-solid-state secondary battery of Figure 3.

[0024] Figure 5 is a cross-sectional view showing the pressurized state of the all-solid-state secondary battery of Figure 4.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] Cathode for all-solid-state secondary batteries

[0030] 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.

[0031] 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.

[0032] 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.

[0033] vanadium oxide

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Fluorine resin binder

[0040] 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.

[0041] 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.

[0042] 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.

[0043] positive electrode active material

[0044] 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.

[0045] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0046] Li a A 1-b Xb O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0047] 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);

[0048] 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);

[0049] 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);

[0050] 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);

[0051] 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);

[0052] 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);

[0053] 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);

[0054] 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);

[0055] 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);

[0056] 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);

[0057] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0058] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0059] Li a Mr 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0060] Li a Mn2G bO4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0061] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0062] QO2; QS2; LiQS2;

[0063] V2O5; LiV2O5;

[0064] LiZO2;

[0065] LiNiVO4;

[0066] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0067] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0068] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0069] 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.

[0070] 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).

[0071] 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.

[0072] [Chemical Formula 1]

[0073] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0074] 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.

[0075] [Chemical Formula 2]

[0076] Li a2 Co x2 M 3 1-x2 O2

[0077] 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.

[0078] [Chemical Formula 3]

[0079] Li a3 Fe x3 M 4 (1-x3) PO4

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Sulfide-based solid electrolyte

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] Challenge

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] All-solid-state secondary battery

[0099] 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.

[0100] 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.

[0101] cathode

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The above binder serves to adhere the negative active material particles well to each other and also to adhere the negative active material well to the current collector. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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 ㎛.

[0127] 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.

[0128] solid electrolyte layer

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] The thickness of the solid electrolyte layer may be, for example, 10 ㎛ to 150 ㎛.

[0135] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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-.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] Fig. 3 is a cross-sectional view showing an all-solid-state secondary battery according to a first embodiment of the present invention. Referring to Fig. 3, the all-solid-state secondary battery (1) of the first embodiment includes a negative electrode (400), a solid electrolyte layer (310'), a positive electrode (200), and an elastic layer (500). The all-solid-state secondary battery (1) of the first embodiment is called a mono-cell composed of a single-sided electrode plate.

[0146] 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).

[0147] The solid electrolyte layer (310') can be formed as a film by directly coating a solid electrolyte film on the negative electrode active material layer (403). Specifically, the solid electrolyte layer (310') includes a first solid electrolyte layer (311') and a second solid electrolyte layer (312') that are laminated to each other.

[0148] The first solid electrolyte layer (311') can be formed as a film by directly coating first solid electrolyte particles on the negative electrode active material layer (403). The second solid electrolyte layer (312') can be formed as a film by directly coating second solid electrolyte particles on the first solid electrolyte layer (311'). A positive electrode (200) including a positive electrode active material layer (203) and a positive electrode current collector (201) is laminated on the second solid electrolyte layer (312').

[0149] Accordingly, the all-solid-state secondary battery (1) of the first embodiment forms a laminated structure of the negative electrode current collector (401) and the negative electrode active material layer (403) of the negative electrode (400), the first solid electrolyte layer (311') and the second solid electrolyte layer (312') which are the solid electrolyte layer (310'), and the positive electrode active material layer (203) and the positive electrode (200) of the positive electrode current collector (201).

[0150] 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, it is provided on each side of 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 (310') 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.

[0151] The elastic layer (500) provides flatness between the negative electrode (400) and the first solid electrolyte layer (311') with buffering force and elasticity in response to expansion and contraction due to Li precipitation and dissociation of the negative electrode (400) during charging and discharging, and provides flatness between the second solid electrolyte layer (312') and the positive electrode (200).

[0152] The elastic layer (500) is provided on both sides of the laminate of the cathode (400) / solid electrolyte layer (310') / anode (200) and is supported by the end plate (20). The elastic layer (500) is arranged at the outermost part of the laminate and provides cushioning and elasticity against changes in the volume of the laminate during charging and discharging.

[0153] Fig. 4 is a longitudinal cross-sectional view showing the state before pressurization of the all-solid-state secondary battery of Fig. 3, and Fig. 5 is a longitudinal cross-sectional view showing the state after pressurization of the all-solid-state secondary battery of Fig. 4. There is a process of pressurizing a laminate during the manufacturing process of the all-solid-state secondary battery (1).

[0154] Before pressurizing the laminate, the first solid electrolyte layer (311) formed on the cathode (400) side of the solid electrolyte layer (310) is formed with a first thickness (t1), and the second solid electrolyte layer (312) formed on both sides (200) is formed with a second thickness (t2) greater than the first thickness (t1) (t2>t1).

[0155] Before pressurization, the first and second thicknesses (t1, t2) of the first and second solid electrolyte layers (311, 312) (see Fig. 4) are thinned to the first' and second' thicknesses (t1', t2') of the first and second solid electrolyte layers (311', 312') after pressurization (see Fig. 5). That is, the first and second thicknesses (t1, t2) are thinned to the first' and second' thicknesses (t1', t2') (t1>t1', t2>t2').

[0156] The first solid electrolyte layer (311) has an average particle diameter (D50) of 10 nm to 10 μm of the first solid electrolyte particles (SEP1) and forms a first thickness (t1) of 50 μm to 100 μm before pressurization. The second solid electrolyte layer (312) has an average particle diameter (D50) of 10 nm to 10 μm of the second solid electrolyte particles (SEP2) and forms a second thickness (t2) of 25 μm to 50 μm before pressurization.

[0157] As an example, in the solid electrolyte layer (310), the first solid electrolyte layer (311) includes round-type first solid electrolyte particles (SEP1, solid electrolyte particles) (see FIG. 4). After pressurization, the first solid electrolyte layer (311') in the solid electrolyte layer (310') is formed on one surface of the negative active material layer (403) with a first 'thickness (t1') of 2 ㎛ or less (see FIG. 5). The round-type first solid electrolyte particles (SEP1') enable uniform pressurization even in the case of uniaxial pressurization such as roll press.

[0158] More specifically, the first solid electrolyte layer (311) of the solid electrolyte layer (310) can form the first solid electrolyte particles (SEP) in one of a spherical, oval, and disc shape. The spherical, oval, and disc-shaped first solid electrolyte particles (SEP1) enable more uniform pressing by distributing the load even in the case of uniaxial pressing such as roll pressing (see FIG. 4). After pressing, the first solid electrolyte layer (311') is formed on one surface of the negative electrode active material layer (403) with a first 'thickness (t1') of 2 ㎛ or less (see FIG. 5). The spherical, oval, and disc-shaped first solid electrolyte particles (SEP1') enable uniform pressing even in the case of uniaxial pressing such as roll pressing.

[0159] In comparison, the second solid electrolyte layer (312) of the solid electrolyte layer (310) includes sharp-type second solid electrolyte particles (SEP2, solid electrolyte particles) (see FIG. 4). After pressurization, the second solid electrolyte layer (312') is formed on one surface of the negative active material layer (403) with a second'thickness (t2') of 3 µm to 5 µm (see FIG. 5). The sharp-type second solid electrolyte layer (312') formed on the first solid electrolyte layer (311') helps uniform pressurization together with the first solid electrolyte layer (311').

[0160] In a state where uniform pressurization is enabled by the first solid electrolyte layer (311), the sharp type second solid electrolyte particles (SEP2') disperse the load even in the case of uniaxial pressurization such as a roll press, thereby enabling more uniform pressurization.

[0161] The negative active material layer (403) includes a carbon layer of several tens of nm in size containing Ag powder of several tens of nm in size and a binder. The negative active material layer (403) is a structure that has a very weak physical bonding force even though it is in a pre-pressurized state.

[0162] Even when the first solid electrolyte particles (SEP1) of the first solid electrolyte layer (311) having the first thickness (t1) are pressed together in one axis and the thickness of the first solid electrolyte particles (SEP1') of the first solid electrolyte layer (311') becomes thinner (from t1 to t1'), the negative active material layer (403) is not damaged. Accordingly, a short circuit due to the detachment of the negative active material can be prevented.

[0163] Before and after pressurization, the first solid electrolyte layer (311, 311') is formed on the negative electrode active material layer (403), so that the second solid electrolyte particles (SEP2, SEP2') do not reach the negative electrode active material layer (403) despite being sharp, and thus do not damage the negative electrode active material layer (403).

[0164] The first solid electrolyte particles (SEP1, SEP1') facing the negative electrode active material layer (403) have a small particle size and form a soft powder due to their round structure. The first solid electrolyte layer (311, 311') includes the first solid electrolyte particles (SEP1, SEP1'), and before pressurization, the first solid electrolyte particles (SEP1) can be manufactured in a wet manner. The first solid electrolyte particles (SEP1, SEP1') disposed on the negative electrode (400) side are manufactured in a wet manner to form particles with a smooth, round, and fine surface.

[0165] The second solid electrolyte particles (SEP2, SEP2') facing the positive electrode active material layer (203) have a large particle size and form sharp powder due to their sharp structure. The second solid electrolyte layer (312, 312') includes the second solid electrolyte particles (SEP2, SEP2'), and before pressurization, the second solid electrolyte particles (SEP2) can be manufactured in a dry manner. The second solid electrolyte particles (SEP2, SEP2') disposed on the positive electrode (200) side are manufactured in a dry manner to form large particles with a rough and sharp surface.

[0166] More specifically, the first solid electrolyte layer (311) is formed of round-type first solid electrolyte particles (SEP1', solid electrolyte particles) (see FIG. 4). After pressurization, the first solid electrolyte layer (311') is formed on one surface of the negative electrode active material layer (403) with a first 'thickness (t1') of 0.5 µm to 1 µm (see FIG. 5).

[0167] In comparison, the second solid electrolyte layer (312) is formed of sharp-shaped second solid electrolyte particles (SEP2) (see FIG. 4). After pressurization, the second solid electrolyte layer (312') is formed on one surface of the negative electrode active material layer (403) with a second thickness (t2') of 3 µm to 5 µm (see FIG. 5). The second thickness (t2') is formed to be larger than the first thickness (t1') (t2>t1). The first solid electrolyte layers (311, 311') are formed on the negative electrode active material layer (403) side with the first, first thicknesses (t1, t1') and can be formed with a minimum thickness that prevents damage to the negative electrode active material layer (403).

[0168] The all-solid-state secondary battery (1) of the first embodiment is manufactured in a dry manner to improve the performance of the battery, and reduces the amount of the second solid electrolyte particles (SEP2) with a rough surface, while the first solid electrolyte particles (SEP1) with a smooth surface, manufactured in a wet manner but with somewhat lower performance, are partially used on the negative electrode (400) side, thereby minimizing the deterioration of the performance of the all-solid-state secondary battery (10) and preventing damage to the negative electrode (400).

[0169] In this way, the first solid electrolyte particles (SEP1, SEP1') are formed as powder particles having a round shape and a small diameter, and face the negative electrode active material layer (403) and, after pressurization, form a first 'thickness (t1') of 0.5 µm to 1 µm. The second solid electrolyte particles (SEP2, SEP2') are formed as powder particles having a sharp shape and a larger diameter than the first solid electrolyte particles (SEP1, SEP1'), and face the positive electrode active material layer (203) and, after pressurization, form a second 'thickness (t2') of 3 µm to 5 mm. In this case, the negative electrode (400) is not damaged after roll pressing. Therefore, a short circuit due to the detachment of the negative electrode active material is prevented.

[0170] In the all-solid-state secondary battery (1) of the first embodiment, damage to the surface of the negative electrode active material layer (403) due to the solid electrolyte layer (310') is reduced, so that no physical defects occur at the interface between the solid electrolyte layer (310') and the negative electrode active material layer (403). As a result, short circuits are not induced during charging and discharging, and a long lifespan is possible.

[0171] Experimental examples applying the first solid electrolyte layer (311, 311') and the second solid electrolyte layer (312, 312') of the first embodiment are described. Experimental examples 1 to 7 confirmed the uniformity of pressurization, initial capacity, and short-circuit occurrence time for the first solid electrolyte layer (311, 311') and the second solid electrolyte layer (312, 312').

[0172] In the first to third comparative examples, only the solid electrolyte layer corresponding to the second solid electrolyte layer (312, 313') was applied without applying the first solid electrolyte layer (311, 311'), and the uniformity of pressurization, initial capacity, and short-circuit occurrence time for the solid electrolyte layer were confirmed. The solid electrolyte particle size was D50. That is, in the first to third comparative examples, the first solid electrolyte particles, which are wet-manufactured and consist of smooth, round, and fine particles, were not placed on the negative electrode side.

[0173] Cathode solid electrolyte layer evaluation pre-pressurized layer 1 (cathode facing) 2nd layer (anode facing) shape size (D50 )(mm)Pressure thickness(mm)Shape size(D) 50 )(mm)Pressurized thickness (mm)Pressurized uniformityInitial capacity (mAh / g)Short circuit occurrence timeFirst experiment exampleApplied round type0.550.0Sharp type3.050.0Good190.0>200Second experiment exampleApplied round type0.575.0Sharp type3.025.0Good175.0>250Third experiment exampleApplied round type0.5100.0---Excellent150.0>300Fourth experiment exampleApplied round type1.050.0Sharp type3.050.0Good175.0>180Fifth experiment exampleApplied round type1.075.0Sharp Type 3.025.0 Good 165.0>250 Experiment 6 Example applied Round type 1.0100.0---Excellent 135.0>280 Experiment 7 Example not applied Round type 0.550.0 Sharp type 3.050.0 Average 120.0>100 Experiment 1 Comparison Example not applied---Square 1.0100.0 Poor 80.0<1 Experiment 2 Comparison Example not applied---Square 3.0100.0 Poor 50.0<1 Experiment 3 Comparison Example not applied---Square 5.0100.0 Poor 20.0<1

[0174] In the negative electrode (400), the pre-pressure (experimental examples 1 to 6) of the negative electrode active material layer (403) is 1.5 (ton.f / cm) in line pressure, and RT (room temperature) is 25°C. In the positive electrode (200), the specific capacity of the positive electrode active material layer (203) is 200 (mAh / g), the positive electrode active material is 85%, and 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℃.

[0175] The cathode (400) / solid electrolyte layer (300) / anode (200) 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 (mm), 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.

[0176] Experimental examples and comparative examples show the application of a high-temperature roll press to the production of an all-solid-state battery containing a sulfide-based solid electrolyte, and the configuration of the negative electrode (400) and the first solid electrolyte layer (311, 311') so that, when the roll press is applied, no physical defects that may cause a short circuit during charging and discharging are generated at the interface between the negative electrode (400) and the first sulfide-based solid electrolyte layer (311, 311').

[0177] Experimental examples and comparative examples show that, unlike conventional isostatic pressing, it is difficult to uniformly pressurize with conventional solid electrolyte powder and single layer when applying pressurization with a roll press that has severe lateral elongation and shear on the film.

[0178] Experimental examples and comparative examples show what characteristics the state of the cathode (400) and the state of the first solid electrolyte layer (311, 311') must have in order for the two different layers to be physically uniformly pressurized.

[0179] The cathode (400) is a carbon layer containing silver particles tens of nanometers in size. The carbon layer is very fragile and susceptible to scratches. Uneven lithium deposition occurs at the scratched area, causing a short circuit. Therefore, pre-pressing is necessary in the case of roll pressing rather than isotropic pressing.

[0180] The first solid electrolyte layer (311, 311') of the round-shaped first solid electrolyte particle (SEP1, SEP1') was applied to the first to seventh experimental examples, and the second solid electrolyte layer (312, 312') of the sharp-shaped second solid electrolyte particle (SEP2, SEP2') was applied to the first, second, fourth, fifth, and seventh experimental examples. In the first to third comparative examples, the first solid electrolyte layer (311, 311') was not applied, and the solid electrolyte layer of the square-shaped solid electrolyte particle was applied.

[0181] Pre-pressurization was not applied to the cathodes of Comparative Examples 1 to 3, and a typical coarse sulfide-based solid electrolyte powder was applied to the solid electrolyte layer. Comparative Examples 1 to 3 exhibited poor uniformity of pressurization, making it difficult to evaluate normal charge and discharge.

[0182] In Experimental Examples 1 to 7, pre-pressurization was applied to the cathode (400), and in Experimental Example 7, pre-pressurization was not applied to the cathode (400). Since the first solid electrolyte layer (311, 311') of the round first solid electrolyte particles (SEP1, SEP1') smoothly faced the cathode (400), the uniformity of the pressurization was appropriate. Since the powder properties of the first solid electrolyte layer (311, 311') itself are poor, the initial capacity is not high, but it is superior to Comparative Examples 1 to 3.

[0183] In the first to sixth experimental examples, it can be confirmed that the uniformity of pressurization, initial capacity, and short-circuit occurrence time are slightly different depending on the configuration of the first solid electrolyte layer (311, 311') on the cathode (400) to which pre-pressurization is applied, i.e., the first thickness (t1, t1').

[0184] In the third and sixth experimental examples, the first solid electrolyte layer (311, 311') of the first solid electrolyte particles (SEP1, SEP1') manufactured in a wet manner and composed of smooth, round, and fine particles was disposed throughout, and the second solid electrolyte layer (312, 312') of the second solid electrolyte particles manufactured in a dry manner and composed of rough, sharp, and large particles was not used.

[0185] Experimental examples 3 and 6 partially use first solid electrolyte particles (SEP1, SEP1') that are manufactured wet and have smooth surfaces, thereby preventing damage to the negative electrode (400), thereby reducing physical defects within the cell while maintaining the performance of the all-solid-state secondary battery. Experimental examples 3 and 6 have superior performance in terms of pressurization uniformity, initial capacity, and short-circuit occurrence time compared to comparative examples 1 to 3.

[0186] In the first, second, fourth, fifth, and seventh experimental examples, a first solid electrolyte layer (311, 311') of first solid electrolyte particles (SEP1, SEP1') manufactured wet and composed of smooth, round, and fine particles with a smooth surface is placed on the cathode (400) side, and a second solid electrolyte layer (312, 312') of second solid electrolyte particles (SEP2, SEP2') manufactured dry and composed of rough, sharp, and large particles with a rough surface is placed on the anode (200) side.

[0187] Experimental examples 1, 2, 4, 5, and 7 are manufactured in a dry manner to improve the performance of the battery, and reduce the amount of the second solid electrolyte particles (SEP2, SEP2') with a rough surface, while partially using the first solid electrolyte particles (SEP1, SEP1') manufactured in a wet manner to have a smooth surface, although the performance is somewhat lowered, thereby preventing damage to the negative electrode (400), thereby maintaining the performance of the all-solid-state secondary battery (1) and reducing physical defects inside the cell.

[0188] Therefore, the first, second, fourth, fifth, and seventh experimental examples can have superior performance in terms of pressure uniformity, initial capacity, and short-circuit occurrence time compared to the first to third comparative examples in which the first solid electrolyte layer (311, 311') of the first solid electrolyte particles (SEP1, SEP1') is not arranged.

[0189] 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.

[0190] - Explanation of symbols -

[0191] 1, 100: All-solid-state secondary battery 20: End plate

[0192] 200: Anode 201: Anode current collector

[0193] 203: Cathode active material layer 300, 310: Solid electrolyte layer

[0194] 311, 311': first solid electrolyte layer 312, 312': second solid electrolyte layer

[0195] 400, 400': Cathode 401: Cathode current collector

[0196] 403: Negative active material layer 500: Elastic layer

[0197] SEP1, SEP1': first solid electrolyte particles SEP2, SEP2': second solid electrolyte particles

[0198] t1, t1': first, 1'th thickness t2, t2': second, 2'th thickness

Claims

1. Cathode; A first solid electrolyte layer provided on one surface of the above cathode; A second solid electrolyte layer provided on one surface of the first solid electrolyte layer; and It includes an anode provided on one surface of the second solid electrolyte layer, The above first solid electrolyte layer Containing a round type first solid electrolyte particle, An all-solid-state secondary battery formed with a first thickness of 2㎛ or less.

2. In paragraph 1, An all-solid-state secondary battery in which the first solid electrolyte particles are formed into one of a spherical, oval, and disc shape.

3. In paragraph 1, The second solid electrolyte layer includes second solid electrolyte particles, An all-solid-state secondary battery in which the second solid electrolyte particles are formed in a sharp type.

4. In paragraph 1, The above first solid electrolyte layer An all-solid-state secondary battery comprising first solid electrolyte particles manufactured by a wet process.

5. In paragraph 4, The above second solid electrolyte layer An all-solid-state secondary battery comprising second solid electrolyte particles in the form of powder manufactured by a dry process.

6. In paragraph 1, The second solid electrolyte layer includes second solid electrolyte particles, An all-solid-state secondary battery, wherein the second solid electrolyte particles have a second thickness of 3 ㎛ to 5 ㎛.

7. In paragraph 1, An all-solid-state secondary battery, wherein the first solid electrolyte particles have a first thickness of 0.5 μm to 1 μm.

8. In paragraph 1, The above first solid electrolyte particles are formed with an average particle diameter (D50) of 10 nm to 10 μm, The above first solid electrolyte layer An all-solid-state secondary battery that forms a first thickness of 50㎛ to 100㎛ before pressurization.

9. In paragraph 8, The second solid electrolyte layer includes second solid electrolyte particles, The above second solid electrolyte particles are formed with an average particle diameter (D50) of 10 nm to 10 μm, An all-solid-state secondary battery, wherein the second solid electrolyte layer forms a second thickness of 25 μm to 50 μm before pressurization.

10. In paragraph 1, The first solid electrolyte layer is formed with a first thickness, An all-solid-state secondary battery, wherein the second solid electrolyte layer is formed to have a second thickness greater than the first thickness.

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