Anode for all-solid-state battery and all-solid-state battery comprising same

Abstract

The present invention relates to an anode for an all-solid-state battery, a manufacturing method therefor, and an all-solid-state battery comprising the anode, the anode comprising: an anode current collector; and an anode layer disposed on the anode current collector and containing an anode active material, a solid electrolyte, polytetrafluoroethylene, and polyvinylidene fluoride, wherein the mixing ratio of polytetrafluoroethylene and polyvinylidene fluoride is 95:5 to 80:20 in terms of weight ratio.

Description

Anode for an all-solid-state battery and an all-solid-state battery comprising the same

[0001] The present invention relates to a cathode for an all-solid-state battery and an all-solid-state battery including the same.

[0002] Recently, rapid developments have been made in electronic devices that use batteries, such as cell phones, laptop computers, and electric vehicles.

[0003] Development of all-solid-state batteries using lithium metal as the cathode is underway. All-solid-state batteries are composed entirely of solid materials, specifically those using solid electrolytes. Because the electrolyte is solid, all-solid-state batteries are structurally robust, reducing the risk of fire or explosion due to leakage from external impacts. Furthermore, they can be shaped into a variety of battery shapes.

[0004] One embodiment provides a cathode for an all-solid-state battery exhibiting excellent cycle life characteristics.

[0005] Another embodiment provides an all-solid-state battery comprising the above negative electrode.

[0006] One embodiment provides an all-solid-state battery negative electrode comprising: a current collector; and a negative electrode layer positioned on the current collector and including a negative electrode active material, a solid electrolyte, polytetrafluoroethylene, and polyvinylidene fluoride, wherein the mixing ratio of the polytetrafluoroethylene and the polyvinylidene fluoride is 95:5 to 80:20 by weight.

[0007] An all-solid-state battery negative electrode according to one embodiment can exhibit excellent lifespan characteristics.

[0008] Figure 1 is a cross-sectional view schematically showing an all-solid-state battery according to one embodiment.

[0009] Figure 2 is a cross-sectional view schematically showing an all-solid-state battery according to another embodiment.

[0010] Figure 3 is an FE-SEM photograph of a negative electrode for an all-solid-state battery according to Example 1.

[0011] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention. The present invention is defined solely by the scope of the claims set forth below.

[0012] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0013] “Combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0014] It should be understood that terms such as "include," "comprise," or "have" are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0015] Throughout this specification, when it is said that a part "includes" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0016] In addition, the terms "about", "substantially", etc. used throughout this specification are used in the sense of numerical values ​​or near numerical values ​​when manufacturing and material tolerances inherent to the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0017] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0018] Unless otherwise specified herein, when a part such as a layer, film, region, or plate is said to be “on top of” another part, this includes not only cases where it is “directly on top of” the other part, but also cases where there is another part in between.

[0019] In the present invention, "particle size" or "particle diameter" may be an average particle diameter. In addition, the average particle diameter may be defined as the average particle diameter (D50) based on 50% of the cumulative volume in a particle diameter distribution curve. The particle diameter may be measured by a method widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope, a scanning electron microscope, or a field emission scanning electron microscope (FE-SEM). Alternatively, the average particle diameter (D50) may be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from this. Alternatively, the average particle diameter (D50) may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle diameter (D50) based on 50% of the particle diameter distribution in the measuring device can be calculated.

[0020] "Thickness" may be measured, for example, from photographs taken with an optical microscope such as a scanning electron microscope.

[0021] One embodiment provides an all-solid-state battery negative electrode comprising: a current collector; and a negative electrode layer positioned on the current collector and including a negative electrode active material, a solid electrolyte, polytetrafluoroethylene, and polyvinylidene fluoride, wherein the mixing ratio of the polytetrafluoroethylene and the polyvinylidene fluoride is 95:5 to 80:20 by weight.

[0022] According to one embodiment, the negative electrode comprises polytetrafluoroethylene and polyvinylidene fluoride as binders, suitably in a weight ratio of 95:5 to 80:20. According to another embodiment, the polytetrafluoroethylene and polyvinylidene fluoride may be in a weight ratio of 90:10 to 85:15.

[0023] Polytetrafluoroethylene and polyvinylidene fluoride are dry binders, and thus can appropriately form a cathode layer without using a solvent. In one embodiment, a dry binder refers to a binder that does not use a solvent in the cathode layer composition for forming the cathode layer, i.e., can be used in a dry process.

[0024] In one embodiment, since polytetrafluoroethylene and polyvinylidene fluoride are included in the above content range, even if polytetrafluoroethylene is partially decomposed into LiF during the charge / discharge process, polyvinylidene fluoride included in the above content range can maintain the structural stability of the negative electrode. In addition, since polytetrafluoroethylene, which can be fibrillated at room temperature and thus can be well entangled with the negative electrode active material during electrode manufacturing to form a good negative electrode active material layer in a dry process, is used as the main binder in excess, the fiberization is well achieved in the dry process, so that the uniformity of the negative electrode composition can be maintained. Polyvinylidene fluoride can provide structural stability to the negative electrode layer, further improve adhesiveness, and when used in a small amount together with polytetrafluoroethylene, for example, in a weight ratio of 5 to 20, it can play a role in maintaining cohesion between active materials and adhesion with a substrate.

[0025] If polytetrafluoroethylene and polyvinylidene fluoride are included in a ratio greater than 95 / 5, for example, if polytetrafluoroethylene is included in too much, the structural stability of the negative electrode may decrease with repeated cycles, resulting in deterioration of the lifespan.

[0026] Additionally, when polytetrafluoroethylene and polyvinylidene fluoride are used in a ratio less than 80 / 20, for example, when the polyvinylidene fluoride content increases, there may be problems of non-uniformity resulting in poor dispersibility in the dry manufacturing process.

[0027] In one embodiment, the mixed content of the polytetrafluoroethylene and the polyvinylidene fluoride may be 1 wt% to 7 wt%, 1.5 wt% to 6 wt%, or 2 wt% to 4 wt%, based on 100 wt% of the total weight of the negative electrode layer. When the polytetrafluoroethylene and the polyvinylidene fluoride are included in the negative electrode layer at the above mixing ratio and their mixed content is within the above range, a decrease in ionic conductivity and electrical conductivity due to an excess of binder can be more effectively prevented.

[0028] In the cathode layer according to one embodiment, the polytetrafluoroethylene may be fiberized polytetrafluoroethylene.

[0029] According to one embodiment, the cathode comprises a solid electrolyte and, as described above, uses a dry binder together, eliminating the need for a solvent during the manufacture of the cathode. Therefore, the problem of the solid electrolyte deteriorating due to a reaction between the solid electrolyte and the solvent does not arise.

[0030] The above solid electrolyte may be a sulfide-based solid electrolyte. Since the negative electrode comprises a solid electrolyte, particularly a sulfide-based solid electrolyte with excellent ionic conductivity, sufficient lithium ion conductivity can be exhibited. Therefore, sufficient operation as a battery is possible.

[0031] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (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 S n(m and n are integers greater than or equal to 0 and less than or equal to 12, respectively, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers greater than or equal to 0 and less than or equal to 12, respectively; M is one of P, Si, Ge, B, Al, Ga In), Li a M b P c S d A e (a, b, c, d and e are each integers greater than or equal to 0 and less than or equal to 12, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I). The sulfide-based solid electrolyte may be, for example, Li 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) or Li 7-x PS 6-x I x (0≤x≤2) can be. Also, specifically, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0032] In one embodiment, the sulfide-based solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte. The argyrodite-type sulfide-based solid electrolyte may be, for example, Li a M b P c S d A e(a, b, c, d, and e are all 0 or greater and 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I).

[0033] As specific examples, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 , Li6PS5I, Li 5.75 PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )PS 4.75 Cl 1.25 , (Li 5.72 Cu 0.03 )PS 4.75 Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 , (Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 , (Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , (Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 , Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 , or combinations thereof, but are not limited thereto.

[0034] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof. For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. 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.

[0035] Methods for mixing sulfur-containing raw materials for manufacturing sulfide-based solid electrolytes include mechanical milling and solution methods. Mechanical milling involves placing the starting raw materials in a reactor and vigorously stirring them with a ball mill, thereby finely agitating the starting raw materials 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 manufactured by mixing sulfur-containing raw materials and heat-treating them twice or more, in which case a sulfide-based solid electrolyte with high ionic conductivity and robustness can be manufactured.

[0036] Of course, a commercially available solid electrolyte can be used as the sulfide-based solid electrolyte.

[0037] The above solid electrolyte may be in the form of particles. At this time, the average particle diameter (D50) of the solid electrolyte may be 5.0 ㎛ or less, for example, 0.1 ㎛ to 5.0 ㎛, 0.5 ㎛ to 5.0 ㎛, 0.5 ㎛ to 4.0 ㎛, 0.5 ㎛ to 3.0 ㎛, 0.5 ㎛ to 2.0 ㎛, or 0.5 ㎛ to 1.0 ㎛.

[0038] In one embodiment, the content of the solid electrolyte may be 5 wt% to 28 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%, based on 100 wt% of the entire negative electrode layer. When the content of the solid electrolyte is within the above range, ion conduction between active materials can be facilitated more smoothly.

[0039] In one embodiment, the negative active material may be crystalline carbon, a Si-based material, or a combination thereof, and in another embodiment, the negative active material may be crystalline carbon.

[0040] The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, carbon nanotubes, graphene, or a combination thereof. The crystalline carbon may be amorphous, plate-shaped, flake-shaped, spherical, or fibrous.

[0041] The above Si-based materials include silicon, silicon-carbon composites, and SiOx(0 <x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소(Si를 제외함), 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합에서 선택됨), 또는 이들의 조합일 수 있다.

[0042] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and amorphous carbon coated on the surface of the silicon particles. For example, the composite may include secondary particles (cores) in which silicon primary particles are assembled and an amorphous carbon coating layer (shell) positioned on the surface of the secondary particles. The amorphous carbon may also be positioned between the silicon primary particles, such that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed and present in an amorphous carbon matrix.

[0043] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core.

[0044] The above silicon particles may be nanoparticles. The particle size of the silicon nanoparticles may be 10 nm to 1,000 nm, and according to another embodiment, 10 nm to 200 nm, or 20 nm to 150 nm. When the particle size of the silicon nanoparticles is within the above range, excessive volume expansion occurring during charge and discharge can be suppressed, and the disconnection of the conductive path due to particle fragmentation during charge and discharge can be prevented.

[0045] The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, or a combination thereof.

[0046] In one embodiment, the content of the negative electrode active material may be 70 wt% to 85 wt%, 75 wt% to 85 wt%, or 80 wt% to 85 wt% based on 100 wt% of the entire negative electrode layer. When the content of the negative electrode active material is within the above range, a higher capacity can be obtained.

[0047] The cathode layer according to one embodiment may further include a conductive material. The conductive material is used to provide conductivity to the electrode, and any material that does not cause a chemical change and is electronically conductive can be used in the battery to be constructed. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0048] In one embodiment, the content of the conductive material may be 1 wt% to 10 wt%, 1 wt% to 5 wt%, or 1 wt% to 4 wt% with respect to 100 wt% of the cathode layer.

[0049] The thickness of the cathode layer may be, for example, 1 µm to 500 µm, 1 µm to 200 µm, 1 µm to 100 µm, or 1 µm to 50 µm, but is not limited thereto.

[0050] The negative current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet. The thickness of the negative current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0051] The above-described negative current collector may be formed of the metal as a substrate and may further include a thin film formed on the substrate. The thin film includes an element capable of forming an alloy with lithium, and may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or a combination thereof, but is not limited thereto, and any element capable of forming an alloy with lithium in the art may be used. When the current collector further includes a thin film, when the lithium-containing layer is formed by precipitation during charging, a more planarized lithium-containing layer can be formed, thereby further improving the cycle life of the all-solid-state battery.

[0052] The thickness of the above thin film may be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thin film thickness is within the above range, the cycle life characteristics can be further improved.

[0053] <Method for manufacturing cathode>

[0054] According to one embodiment, a negative electrode can be manufactured by a manufacturing method including a process of mixing a negative electrode active material, a solid electrolyte, and polyvinylidene fluoride to manufacture a mixture, mixing the mixture with polytetrafluoroethylene to manufacture a negative electrode layer mixture, and pressurizing the negative electrode layer mixture to manufacture a negative electrode layer film.

[0055] In the negative electrode layer manufacturing process, if polytetrafluoroethylene is first mixed with the negative electrode active material and solid electrolyte, fiberization occurs, the viscosity of the mixture becomes too high, and it is difficult to mix uniformly with polyvinylidene fluoride, which is not suitable.

[0056] Below, each process is described.

[0057] First, the active material, polyvinylidene fluoride, and solid electrolyte are mixed. A conductive material may also be added during this mixing process. The active material, polyvinylidene fluoride, solid electrolyte, and conductive material can be used in powder form.

[0058] The above mixing process can be carried out by a dry method without using a solvent.

[0059] The above mixing process can be carried out at a speed of 500 rpm to 2500 rpm, 800 rpm to 2000 rpm, or 1000 rpm to 2500 rpm, and can be carried out for 0.5 to 10 minutes, or 1 to 3 minutes. When the above mixing process is carried out under the above speed and time conditions, the advantage of uniform mixing within a range where the active material is not broken during dry mixing can be obtained.

[0060] Next, polytetrafluoroethylene is added to the obtained mixture and stirred to prepare a cathode layer mixture. The stirring process may be performed for 0.5 to 10 minutes or 1 to 3 minutes. Depending on the stirring process, the polytetrafluoroethylene may fiberize and its viscosity may increase, resulting in a clay-like state.

[0061] Next, a pressurizing process is performed to apply pressure to the obtained cathode layer mixture. Prior to the pressurizing process, a flattening process using a roller may be further performed to adjust the desired thickness.

[0062] The above pressurization process can be performed by applying a pressure of 2 MPa to 10 MPa. When the pressurization process is performed within the above pressure range, there may be an advantage in that the pressure is applied uniformly without destroying the physical structure of the mixture.

[0063] The amounts of the negative active material, polytetrafluoroethylene, polyvinylidene fluoride, conductive agent, and solid electrolyte can be appropriately adjusted to achieve the content and mixing ratio in the negative electrode layer described above.

[0064] The thickness of the above cathode layer film may be 1 µm to 100 µm, 10 µm to 80 µm, or 20 µm to 80 µm.

[0065] A negative electrode can be manufactured by positioning a current collector on the manufactured negative electrode layer film. The process of positioning the current collector can be performed by positioning the current collector on the negative electrode layer film before battery manufacturing, or by positioning the negative electrode layer in contact with the solid electrolyte layer during the battery manufacturing process, and then positioning the current collector on the other side of the negative electrode layer that is not in contact with the solid electrolyte.

[0066] All-solid-state battery

[0067] Another embodiment provides an all-solid-state battery comprising the above negative electrode.

[0068] The above-mentioned all-solid-state battery includes a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode. The negative electrode may be a negative electrode according to one embodiment.

[0069] [anode]

[0070] According to one embodiment, a positive electrode of an all-solid-state battery includes a positive electrode current collector and a positive electrode active material layer positioned on one surface of the positive electrode current collector.

[0071] The above-described positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may use at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≤a≤1.8, 0≤b≤0.5); Li a E 1-b B 1 b O 2-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5); Li a E 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤05); Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Co b B 1 c O 2-α F1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mr b B 1 c D 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α≤2); Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); 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); Li a Ni b Co c L 1 d G e O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2( 0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Lia MnG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); or LiFePO4.

[0072] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D 1 is O, F, S, P, or a combination thereof, and E is Co, Mn, or a combination thereof; F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I 1 is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is Mn, Al or a combination thereof.

[0073] According to one implementation example, LiNi is used as the positive electrode active material. x Co y Al z O2(NCA), LiNi x Co y Mn z O2(NCM)(but, 0 <x<1, 0<y<1, 0<z<1, x+y+z=1) 등의 삼성분계 리튬 전이 금속 산화물을 들 수 있다.

[0074] Of course, it is also possible to use a compound having a coating layer on the surface of the compound, or it is also possible to use a mixture of the compound and a compound having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, and a hydroxycarbonate of the coating element. The compounds forming these coating layers may be amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer forming process may use any coating method as long as it can coat the compound with these elements in a method that does not adversely affect the properties of the positive electrode active material (for example, spray coating, dipping, etc.), and since this is well understood by those working in the relevant field, a detailed description thereof will be omitted.

[0075] In addition, as the above coating layer, any known coating layer for the positive electrode active material of an all-solid-state battery can be applied. For example, it can be a buffer layer that plays a role in lowering the interfacial resistance between the positive electrode active material and the solid electrolyte. For example, the buffer layer can include a lithium-metal-oxide, wherein the metal can be one or more elements selected from the group consisting of Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, and Zr. A specific example of the buffer layer can be Li2O-ZrO2 (LZO).

[0076] Furthermore, when the cathode active material is a ternary compound containing nickel, cobalt, and manganese, or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved and metal dissolution from the cathode active material can be further reduced in a charged state. Consequently, the all-solid-state battery can exhibit improved long-term reliability and cycle performance in a charged state.

[0077] The average particle size of the positive electrode active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. For example, the positive electrode active material may include small particles having an average particle size (D50) of 1 μm to 9 μm and large particles having an average particle size (D50) of 10 μm to 25 μm. A positive electrode active material having such a particle size range can be harmoniously mixed with other components within a positive electrode active material layer and can realize high capacity and high energy density.

[0078] 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 crystal. In addition, the above-mentioned positive electrode active material may be in the form of a spherical or nearly spherical shape, or may be polyhedral or irregular.

[0079] In addition, the content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and may be within a range applicable to the positive electrode layer of a conventional all-solid-state secondary battery. For example, with respect to the total 100 wt% of the positive electrode active material layer, the positive electrode active material may be included in an amount of 55 wt% to 99.5 wt%, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0080] The above positive electrode active material layer may further include a binder and / or a conductive material.

[0081] The above binder may include, but is not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0082] The above binder may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on 100 wt% of the total positive electrode active material layer. Within the above content range, the binder can sufficiently exhibit adhesive ability without deteriorating battery performance.

[0083] The conductive material is used to provide conductivity to the electrode, and any material that does not cause chemical changes and is electronically conductive can be used in the battery. Examples of the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0084] 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 100 wt% of 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.

[0085] The above positive electrode active material layer may additionally include a solid electrolyte. The solid electrolyte included in the positive electrode active material layer may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

[0086] The above sulfide-based solid electrolyte is as described in the negative electrode layer. The sulfide-based solid electrolyte included in the positive electrode active material layer may be the same as or different from the sulfide-based solid electrolyte included in the negative electrode layer.

[0087] The above oxide-based solid electrolyte is, 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 mixture thereof.

[0088] The above halide-based solid electrolyte may include a Li element, an M element (M is a metal other than Li), and an X element (X is a halogen). As X, for example, F, Cl, Br, and I may be mentioned. In particular, in the halide-based solid electrolyte, at least one of Br and Cl is suitable as X. In addition, as the M, for example, a metal element such as Sc, Y, B, Al, Ga, or In may be mentioned.

[0089] The composition of the above halide-based solid electrolyte is not particularly limited, but Li 6-3a M a Br b Cl c (In the formula, M is a metal other than Li, and 0 <a<2, 0≤b≤6, 0≤c≤6, b+c=6)로 표현될 수 있다. 이때, 상기 a는 0.75 이상일 수 있고, 1 이상일 수 있고, a는, 1.5 이하일 수 있다. 상기 b는 1 이상일 수 있고, 2 이상일 수 있다. 또한, 상기 c는, 3 이상일 수 있고, 4 이상일 수도 있다. 상기 할라이드계 고체 전해질의 구체적인 예로는 Li3YBr6, Li3YCl6또는 Li3YBr2Cl4를 들 수 있다.

[0090] The above solid polymer electrolytes include, for example, polyethylene oxide, poly(diallyldimethylammonium)trifluoromethanesulfonyl imide (poly(diallyldimethylammonium)TFSI), Cu3N, Li3N, LiPON, and Li3PO. 4· Li2S · SiS2, Li2S · GeS2· Ga2S3, Li2O · 11Al2O3, Na2O · 11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3(0.1≤x≤0.9), Li 1+x Hf 2-x Al x (PO4)3(0.1≤x≤0.9), Na3Zr2Si2PO 12 , Li3Zr2Si2PO 12 , Na5ZrP3O 12 , Na5TiP3O 12 , Na3Fe2P3O 12 , Na4NbP3O 12 , Na-Silicates, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (M is a rare earth element such as Nd, Gd, Dy) Li5ZrP3O 12 , Li5TiP3O 12 , Li3Fe2P3O 12 , Li4NbP3O 12 , Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3(0≤x≤0.8, 0≤y≤1.0, M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 <x≤0.4, 0<y≤0.6, Q는 Al 또는 Ga), Li6BaLa2Ta2O 12 , Li7La3Zr2O 12 , Li5La3Nb2O 12 , Li5La3M2O 12 (M is Nb, Ta) and Li 7+x A x La 3-x Zr2O 12(0 <x<3, A는 Zn) 중에서 선택된 하나 이상을 포함할 수 있다.

[0091] The above anode current collector may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li) or an alloy thereof, and may be in the form of a foil or sheet.

[0092] Solid electrolyte layer

[0093] The above solid electrolyte layer includes a solid electrolyte. The solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a halide-based solid electrolyte, or a solid polymer electrolyte.

[0094] In one embodiment, the inorganic solid electrolyte and / or solid polymer electrolyte, such as the sulfide-based solid electrolyte, sulfide-based solid electrolyte, oxide-based solid electrolyte, and halide-based solid electrolyte, are as described above.

[0095] The above solid electrolyte is in the form of particles, and the average particle diameter (D50) may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.5 μm to 1.0 μm.

[0096] The above solid electrolyte layer may further include a binder. At this time, the binder may be, but is not limited to, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, and any binder used in the relevant technical field may be used. The acrylate polymer may be butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0097] 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 for 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 herein.

[0098] The solid electrolyte layer may further comprise an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The above ionic liquid comprises a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) 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 - It may be a compound containing one or more anions selected from among.

[0104] 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.

[0105] 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 secondary battery can be improved.

[0106] Elastic layer

[0107] An all-solid-state battery according to one embodiment may further include an elastic layer for buffering thickness changes that occur during charging and discharging. The elastic layer may be positioned between the negative electrode and the case.

[0108] The above elastic layer may be a material having an elastic recovery rate of 50% or more and an insulating function, and specifically may be silicone rubber, acrylic rubber, fluorine rubber, nylon, synthetic rubber, or a combination thereof. The above cushioning material may be in the form of a polymer sheet.

[0109] <Method for manufacturing an all-solid-state battery>

[0110] An all-solid-state battery according to one embodiment can be manufactured by a step of preparing a laminate by positioning a cathode, an anode, and a solid electrolyte layer between the cathode and the anode, and pressing the laminate.

[0111] The pressurizing process can be performed at a temperature ranging from 25°C to 90°C. In addition, the pressurizing process can be performed by pressurizing at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, 1 MPa to 500 MPa. The pressurizing time can vary depending on the temperature and pressure, and can be, for example, less than 30 minutes. The pressurizing process can be, for example, isostatic pressing, roll pressing, plate pressing, or warm isostatic pressing.

[0112] The above-mentioned all-solid-state secondary battery may be a unit cell 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 cell is repeated.

[0113] The shape of the above-mentioned all-solid-state secondary 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 secondary battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0114] FIG. 1 is a cross-sectional view of an all-solid-state battery according to one embodiment. Referring to FIG. 1, the all-solid-state 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 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.

[0115] Fig. 2 schematically illustrates an all-solid-state battery according to another embodiment. The all-solid-state battery (100) illustrated in Fig. 2 includes a positive electrode (200) including a positive electrode current collector (201) and a positive electrode active material layer (203), a negative electrode (400) including a negative electrode current collector (401), a negative electrode layer (403), and a solid electrolyte layer (300) positioned between the positive electrode (200) and the negative electrode (400), and includes a battery case (500) in which these are housed, and further includes a lithium precipitation layer (405') between the negative electrode current collector (401) and the negative electrode layer (403). When the all-solid-state battery is charged, the lithium precipitation layer can be formed by lithium ions being released from the positive electrode active material and deposited on the negative electrode current collector (401').

[0116] Hereinafter, examples and comparative examples of the present invention will be described. The following examples are merely exemplary of the present invention, and the present invention is not limited to the following examples.

[0117] (Example 1)

[0118] (1) Cathode manufacturing

[0119] A mixture was prepared by mixing artificial graphite, polyvinylidene fluoride, Ketjen Black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl in powder form using a Thinky mixer at 1000 rpm for 5 minutes.

[0120] A cathode layer mixture was prepared by mixing the above mixture with polytetrafluoroethylene. The mixture was flattened using a roller, and a pressure of 2 MPa was applied to prepare a cathode layer with a thickness of 30 μm.

[0121] At this time, the amount of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl used was 90 wt% of artificial graphite, 3.2 wt% of polytetrafluoroethylene, and 0.8 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0122] The above cathode layer film was placed on a stainless steel (SUS) current collector to manufacture a cathode.

[0123] (2) Manufacturing of solid electrolyte layer

[0124] A solid electrolyte solution was prepared by adding argyrodite-type solid electrolyte Li6PS5Cl to an isobutylyl isobutylate binder solution containing an acrylate polymer (solid content: 50 wt%, mixing ratio of the solid electrolyte and binder: 98.7:1.3 wt ratio).

[0125] The above solid electrolyte solution was applied to a heterogeneous polytetrafluoroethylene film and dried to produce a solid electrolyte layer having a thickness of 100 μm.

[0126] (3) Manufacturing of anode

[0127] LiNi 0.8 Co 0.15 Mn0.05 A cathode composition was prepared by mixing 85 wt% of O2 cathode active material, 13.5 wt% of lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.0 wt% of polyvinylidene fluoride binder, and 0.5 wt% of carbon nanotube conductive material in an N-methyl pyrrolidone solvent.

[0128] The manufactured positive electrode composition was coated on an aluminum positive electrode current collector, dried, and rolled to manufacture a positive electrode.

[0129] (3) Manufacturing of half-cells

[0130] The manufactured negative electrode, solid electrolyte layer, and lithium metal counter electrode were sequentially laminated, and a pressure of 8 MPa was applied to manufacture a half-cell.

[0131] (5) All-solid-state full cell

[0132] The manufactured negative electrode, solid electrolyte layer, and positive electrode were sequentially laminated, and a pressure of 8 MPa was applied to manufacture an all-solid-state battery (full cell).

[0133] (Example 2)

[0134] A negative electrode was manufactured in the same manner as in Example 1, except that the amounts of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl were changed to 90 wt% of artificial graphite, 3.4 wt% of polytetrafluoroethylene, 0.6 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0135] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0136] (Example 3)

[0137] A negative electrode was manufactured in the same manner as in Example 1, except that the amounts of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl were changed to 90 wt% of artificial graphite, 3.6 wt% of polytetrafluoroethylene, 0.4 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0138] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0139] (Example 4)

[0140] A negative electrode was manufactured in the same manner as in Example 1, except that the amounts of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl were changed to 90 wt% of artificial graphite, 3.8 wt% of polytetrafluoroethylene, 0.2 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0141] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0142] (Comparative Example 1)

[0143] A negative electrode was manufactured in the same manner as in Example 1, except that the amounts of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl were changed to 90 wt% of artificial graphite, 3.16 wt% of polytetrafluoroethylene, 0.84 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0144] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0145] (Comparative Example 2)

[0146] A negative electrode was manufactured in the same manner as in Example 1, except that the amounts of artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl were changed to 90 wt% of artificial graphite, 3.84 wt% of polytetrafluoroethylene, 0.16 wt% of polyvinylidene fluoride, 3 wt% of Ketjen black conductive agent, and 3 wt% of argyrodite-type solid electrolyte Li6PS5Cl, based on 100 wt% of the total negative electrode layer mixture.

[0147] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0148] (Comparative Example 3)

[0149] (1) Cathode manufacturing

[0150] A cathode layer mixture was prepared by mixing artificial graphite, polytetrafluoroethylene, polyvinylidene fluoride, Ketjen Black conductive agent, and argyrodite-type solid electrolyte Li6PS5Cl in a weight ratio of 95:4:0:0.8:3:3.

[0151] The above cathode layer film was placed on a stainless steel current collector to manufacture a cathode.

[0152] Half cells and full cells were manufactured in the same manner as in Example 1 except that the above-mentioned negative electrode was used.

[0153] Experimental Example 1) Overvoltage Measurement

[0154] The all-solid-state half-cells manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 were charged at 0.05 C, and the voltage drop began at OCV (Open Circuit Voltage, approximately 2.5 V). Subsequently, the voltage was measured up to the point where an inflection point occurred around 0 mV. This result is shown in Table 1 below as the initial overvoltage.

[0155] Experimental Example 2) Initial Efficiency Evaluation

[0156] For the all-solid-state half-cells manufactured according to Examples 1 to 4 and Comparative Examples 1 to 3, a 0.05C charge / discharge cycle was performed once, and the ratio of the discharge capacity to the charge capacity was calculated as in Equation 1 below to obtain the initial efficiency. The results are shown in Table 1 below.

[0157] [Formula 1]

[0158] Initial efficiency (%) = (discharge capacity / charge capacity)*100

[0159] Experimental Example 3) Life Evaluation

[0160] The solid-state full cells manufactured in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to 100 charge-discharge cycles at 0.33 C. The ratio (C) of the 100-cycle discharge capacity to the 1-cycle discharge capacity was calculated according to Equation 1 below. The ratio (C) was classified according to the following criteria, and the results are shown in Table 1 below.

[0161] [Formula 1]

[0162] C = (100 discharge capacity / 1 discharge capacity) * 100

[0163] X: C<90%

[0164] O: C≥90%

[0165] Overvoltage (mV) Initial efficiency (%) Lifespan (%) Example 115.990.5O Example 216.090.0O Example 315.590.3O Example 415.690.4O Comparative example 116.587.8X Comparative example 216.388.8X Comparative example 315.990.5X

[0166] As shown in Table 1 above, the batteries of Examples 1 to 4 containing polytetrafluoroethylene and polyvinylidene fluoride in a weight ratio of 95:5 to 80:20 exhibited low overvoltage and excellent initial efficiency and lifespan. On the other hand, the batteries of Comparative Examples 1 and 2 containing polytetrafluoroethylene and polyvinylidene fluoride in a weight ratio outside of 95:5 to 80:20 exhibited high overvoltage, somewhat low initial efficiency, and deteriorated lifespan.

[0167] In addition, even though the battery of Comparative Example 3 was manufactured by mixing polytetrafluoroethylene and polyvinylidene fluoride together, even though the battery contained polytetrafluoroethylene and polyvinylidene fluoride in a weight ratio of 95:5 to 80:20, it was found that although the initial efficiency was appropriate, the life characteristics deteriorated as charge and discharge progressed due to the non-uniformity of the binder.

[0168] Experimental Example 4) FE-SEM (Field Emission SEM) Evaluation

[0169] The cathode manufactured in Example 1 was cross-polished to flatten the cross-section, and then measured using FE-SEM. The results are shown in Fig. 3. In Fig. 3, arrows represent artificial graphite, solid circles represent solid electrolytes, and dotted circles represent dry binders, i.e., polytetrafluoroethylene and polyvinylidene fluoride.

[0170] From these results, it can be seen that polytetrafluoroethylene and polyvinylidene fluoride are well positioned within the cathode layer.

[0171] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Negative current collector; and A cathode layer positioned on the above cathode current collector and including a cathode active material, a solid electrolyte, polytetrafluoroethylene, and polyvinylidene fluoride, The mixing ratio of the above polytetrafluoroethylene and the above polyvinylidene fluoride is 95:5 to 80:20 by weight. Cathode for all-solid-state batteries.

2. In paragraph 1, The above negative electrode active material is an all-solid-state battery negative electrode comprising crystalline carbon, Si-based material or a combination thereof.

3. In paragraph 1, The above negative electrode active material is an all-solid-state battery negative electrode made of crystalline carbon.

4. In paragraph 3, The above crystalline carbon is an all-solid-state battery negative electrode made of natural graphite, artificial graphite or a combination thereof.

5. In paragraph 1, An all-solid-state battery negative electrode having a mixing ratio of the polytetrafluoroethylene and the polyvinylidene fluoride of 90:10 to 85:15 by weight.

6. In paragraph 1, The above polytetrafluoroethylene is a solid-state battery negative electrode which is a fiberized polytetrafluoroethylene.

7. In paragraph 1, The above solid electrolyte is an all-solid-state battery negative electrode which is a sulfide-based solid electrolyte.

8. In paragraph 1, An all-solid-state negative electrode for a battery, wherein the mixed content of the polytetrafluoroethylene and the polyvinylidene fluoride is 1 to 7 wt% with respect to 100 wt% of the entire negative electrode layer.

9. In paragraph 1, An all-solid-state battery negative electrode, wherein the content of the negative active material is 70 to 85 wt% with respect to 100 wt% of the entire negative electrode layer.

10. In paragraph 1, An all-solid-state battery negative electrode having a content of the solid electrolyte of 5 to 28 wt% based on 100 wt% of the entire negative electrode layer.

11. In paragraph 1, An all-solid-state negative electrode, wherein the negative electrode layer further includes a conductive material.

12. A mixture is prepared by mixing a negative active material, polyvinylidene fluoride, and a solid electrolyte; A cathode layer mixture is prepared by mixing the above mixture with polytetrafluoroethylene; Pressurizing the above cathode layer mixture A method for manufacturing a cathode for an all-solid-state battery including a process.

13. In paragraph 12, A method for manufacturing an all-solid-state battery negative electrode, wherein the pressurizing process is performed by applying a pressure of 2 MPa to 10 MPa.

14. In paragraph 12, A method for manufacturing an anode for an all-solid-state battery, wherein the anode active material is crystalline carbon, a Si-based material, or a combination thereof.

15. In paragraph 12, A method for manufacturing an all-solid-state battery negative electrode, wherein the negative active material is crystalline carbon.

16. In paragraph 12, A method for manufacturing an all-solid-state negative electrode, wherein in the negative electrode mixture, the mixing ratio of the polytetrafluoroethylene and the polyvinylidene fluoride is 95:5 to 80:20 by weight.

17. In paragraph 16, A method for manufacturing an all-solid-state negative electrode, wherein in the negative electrode mixture, the mixing ratio of the polytetrafluoroethylene and the polyvinylidene fluoride is 90:10 to 85:15 by weight.

18. In paragraph 12, A method for manufacturing an all-solid-state battery negative electrode, wherein the above solid electrolyte is a sulfide-based solid electrolyte.

19. The cathode of any one of clauses 1 to 11; Bipolar; and A solid electrolyte layer positioned between the cathode and the anode An all-solid-state battery comprising:

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