Method and device for solid-state battery pressurization evaluation

Abstract

The present invention relates to a method and a device for solid-state battery pressurization evaluation. The method comprises the steps of: (1) manufacturing a test sample by positioning a pressure-sensitive member on at least one of the top surface and bottom surface of a solid-state battery including a cathode, an anode, and a solid electrolyte layer positioned between the cathode and the anode; (2) pressurizing the test sample in the thickness direction of the solid-state battery; (3) obtaining image information of the pressure-sensitive member after the completion of the pressurization in the step (2); and (4) determining the pressure distribution of the solid-state battery from the obtained image information of the pressure-sensitive member. The device comprises a pressurization means for providing image information to the test sample and the pressure-sensitive member so as to identify the pressure distribution.

Description

Pressure evaluation method and pressure evaluation device for all-solid-state batteries

[0001] The present invention relates to a pressure evaluation method and a pressure evaluation device for an all-solid-state battery.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0190035, filed December 22, 2023, and Korean Patent Application No. 10-2024-0170546, filed November 26, 2024, which are incorporated herein by reference in their entirety.

[0003] Lithium secondary batteries have been mainly applied to small fields such as mobile devices and laptop computers, but recently, the research direction is expanding to medium and large fields such as energy storage systems (ESS) and electric vehicles (EVs).

[0004] For these medium and large-sized lithium secondary batteries, unlike small ones, the operating environment (e.g., temperature, shock) is harsher, and more batteries must be used, so safety must be secured along with excellent performance and an appropriate price.

[0005] Most commercially available lithium secondary batteries utilize organic liquid electrolytes, which consist of lithium salts dissolved in flammable organic solvents. This poses a potential risk of leakage, fire, and explosion. Therefore, replacing these liquid electrolytes with solid electrolytes is gaining attention as a viable solution to address these safety concerns.

[0006] Lithium secondary batteries using solid electrolytes offer increased safety, improved reliability by preventing electrolyte leakage, and the ease of manufacturing thin batteries. Furthermore, the use of lithium metal as the anode enhances energy density. Consequently, solid electrolytes are attracting attention as next-generation batteries, promising applications in both compact secondary batteries and high-capacity secondary batteries for electric vehicles.

[0007] However, lithium secondary batteries using solid electrolytes have lower ionic conductivity than liquid electrolytes, and their output characteristics deteriorate, especially at low temperatures. Furthermore, solid electrolytes have lower surface adhesion to active materials than liquid electrolytes, and the volume of the active material expands during the charge / discharge process, increasing interfacial resistance. Furthermore, solid electrolytes are distributed in a non-contact state with the electrode active material, which reduces output characteristics and capacity compared to the amount of conductive material introduced.

[0008] In addition, even in the case of lithium secondary batteries using solid electrolytes, lithium dendrites are inevitably generated during the charging and discharging process of the battery, and lithium dendrites formed in a dendritic shape can grow by penetrating the solid electrolyte as described above, causing reversible lithium loss and short-circuiting of the battery, and are evaluated as factors that have a negative impact on the lifespan of lithium secondary batteries.

[0009] As a solution to these problems, a 'pressurization process' is performed to apply external force during the operation of lithium secondary batteries using solid electrolytes, but it is difficult to easily confirm whether uniform pressure is applied to the entire area of ​​the battery.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Japanese Patent Application Publication No. 2012-172984 (September 10, 2012)

[0013] The purpose of the present invention is to provide a method for evaluating the pressure of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, wherein a pressure-sensitive member is positioned on the all-solid-state battery, and then pressurized, and the pressure distribution of the all-solid-state battery can be determined through image information of the pressure-sensitive member obtained according to the pressurization.

[0014] Another object of the present invention is to provide a pressure evaluation device for an all-solid-state battery, including a test object including an all-solid-state battery in which the pressure-sensitive member is positioned, and a pressure means for providing image information so as to confirm the pressure distribution on the pressure-sensitive member.

[0015] A first aspect of the present invention provides a method for evaluating a pressure of an all-solid-state battery including a solid electrolyte, comprising: (1) a step of manufacturing a test subject by positioning a pressure-sensitive member on at least one of an upper surface or a lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode; (2) a step of pressing the test subject in the thickness direction of the all-solid-state battery using a pressing means; (3) a step of acquiring image information of the pressure-sensitive member after the pressing in step (2) is completed; and (4) a step of determining a pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member.

[0016] In one specific example of the present invention, the step of acquiring image information of the pressure-sensitive member in step (3) is to acquire information on the intensity of pressure applied to the all-solid-state battery and the uniformity of pressure through the degree of discoloration, the discolored area, and the distribution of the discolored portion in the pressure-sensitive member.

[0017] In one specific example of the present invention, the step of determining the pressure distribution of the all-solid-state battery from the image information of the pressure-sensitive member obtained in the step (4) is to obtain color information for each of a plurality of unit inspection areas within the image of the pressure-sensitive member, calculate an average value thereof, and compare the average value with a standard color sample of the pressure-sensitive member to determine the pressure distribution of the all-solid-state battery.

[0018] In one specific example of the present invention, the pressure reducing member is included in the test body n times (provided that n is an integer greater than or equal to 1).

[0019] In one specific embodiment of the present invention, in one specific embodiment of the present invention, the test body includes p solid-state batteries and q pressure sensitive members (provided that p and q are the same as or different from each other and are each independently an integer greater than or equal to 1), and when the p solid-state batteries are sequentially stacked, the pressure sensitive member is included between each solid-state battery.

[0020] In one specific example of the present invention, the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced, and the pressure applied to the subject is measured based on the color development state of the pressure-sensitive paper.

[0021] In one specific embodiment of the present invention, the pressurizing means is a device including a hydraulic press, a jig or a warm hydrostatic press.

[0022] In one specific example of the present invention, before the pressurization in step (2), an elastic member is further included on at least one of the upper or lower surfaces of the subject in step (1).

[0023] In one specific example of the present invention, the ratio (a / b) of the size (a) of the cross-sectional area of ​​the part of the pressurizing means that comes into contact with the test object during the pressurizing step (2) and the size (b) of the cross-sectional area of ​​the part of the test object that comes into contact with the pressurizing means is 8:1 or more.

[0024] A second aspect of the present invention provides a pressure evaluation device for an all-solid-state battery, including a test body having a pressure-sensitive member positioned on at least one of an upper surface or a lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and a pressure applying means for applying pressure to the test body to provide image information so as to confirm a pressure distribution on the pressure-sensitive member.

[0025] In one specific example of the present invention, the pressure applied to the subject is applied in the thickness direction of the all-solid-state battery.

[0026] In one specific example of the present invention, the pressure reducing member is included in the test body n times (provided that n is an integer greater than or equal to 1).

[0027] In one specific example of the present invention, the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced.

[0028] In one specific embodiment of the present invention, the pressurizing means is a device including a hydraulic press, a jig or a warm hydrostatic press.

[0029] In one specific embodiment of the present invention, an elastic member is further included on at least one of the upper and lower surfaces of the subject.

[0030] According to the present invention, by obtaining information on the pressure applied to an all-solid-state battery through image information on a pressure member obtained in a method for evaluating the pressure of an all-solid-state battery, it is possible to confirm and simultaneously visualize the degree of fastening pressure applied in the plane direction or thickness direction of the all-solid-state battery, thereby obtaining information that can determine a method for applying fastening pressure to an all-solid-state battery, or the material and thickness of an elastic member further included in the all-solid-state battery, the size of a jig, etc. In addition, there is an advantage in that the pressure applied to an all-solid-state battery through the pressure member can be easily confirmed through the image information of the pressure-reducing member through a pressure evaluation device including a test object including an all-solid-state battery and a pressure means.

[0031] Figure 1 is a schematic diagram showing a test subject of a pressure evaluation method according to one specific example of the present invention.

[0032] Figure 2 is a schematic diagram showing a test subject of a pressure evaluation method according to another specific example of the present invention.

[0033] Figure 3 is a schematic diagram showing the contact state between a pressurizing means and a subject during pressurization according to one specific example of the present invention.

[0034] Figure 4 is a photograph showing a test subject of a pressure evaluation method according to one specific example of the present invention.

[0035] FIGS. 5 to 7 are photographs showing a pressurizing means according to one specific example of the present invention, and FIG. 8 is a photograph showing a test subject to which pressure is applied according to the pressurizing means according to FIG. 7.

[0036] Figures 9 and 10 illustrate image information of a pressure-sensitive member to which pressure is applied according to one specific example of the present invention.

[0037] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings, and should be interpreted with meanings and concepts that conform to the technical spirit of the present invention based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention. Therefore, the configurations described in the embodiments described in this specification are merely the most preferred specific examples of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0038] In this specification, when a part is said to 'include' a certain component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated.

[0039] In this specification, descriptions that specify or add elements can be applied to all inventions unless there are special limitations, and are not limited to specific inventions.

[0040] In this specification, the singular expressions used throughout the description and claims of the invention include the plural, unless otherwise stated.

[0041] In this specification, throughout the description and claims of the invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases of including A, including B, or including A and B.

[0042] In this specification, when a component is said to be "above" or "below" another component, it means not only that it is positioned on the upper or lower side in direct contact with the other component, but also that another component exists between the component and the other component.

[0043] In this specification, all numerical ranges include both extreme values ​​and all intermediate values ​​therebetween, unless explicitly stated otherwise.

[0044]

[0045] Pressure evaluation method for all-solid-state batteries

[0046] The present invention provides a method for evaluating the pressure of an all-solid-state battery.

[0047] Hereinafter, the pressure evaluation method of the all-solid-state battery of the present invention will be described in detail.

[0048] The pressure evaluation method of the all-solid-state battery of the present invention comprises the steps of (1) preparing a test subject by positioning a pressure-sensitive member on at least one of the upper surface or the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, (2) pressing the test subject in the thickness direction of the all-solid-state battery, (3) obtaining image information of the pressure-sensitive member after the pressurization in step (2) is completed, and (4) determining the pressure distribution of the all-solid-state battery from the obtained image information of the pressure-sensitive member.

[0049] First, (step (1)) in a method for evaluating the pressure of an all-solid-state battery according to the present invention, a test object is manufactured by positioning a pressure-sensitive member on at least one of the upper surface or the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode.

[0050] Figure 1 schematically illustrates a test subject (100a) that is the target of a pressure evaluation method of a battery according to one specific example of the present invention.

[0051] Referring to FIG. 1, a test body (100a) according to one specific example of the present invention includes an electrode assembly (10) of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and a pressure-sensitive member (20), and the pressure-sensitive member is positioned on the upper or lower surface of the electrode assembly. In addition,

[0052] In one specific example of the present invention, the subject is in a form in which the all-solid-state battery and the pressure-sensitive member are housed in an outer material (50) such as a pouch.

[0053] Figure 4 is an image showing the external appearance of a test subject in which the solid-state battery and pressure-sensitive member are stored and sealed in a pouch.

[0054] In one specific example of the present invention, the test object has a pressure-sensitive member positioned only on the upper surface of the electrode assembly, a pressure-sensitive member positioned only on the lower surface of the electrode assembly, or a pressure-sensitive member positioned on both the upper surface and the lower surface of the electrode assembly.

[0055] In addition, the subject according to the pressure evaluation method of an all-solid-state battery according to one specific example of the present invention includes a plurality of electrode assemblies and a plurality of pressure-sensitive members, and when the subject includes a plurality of electrode assemblies and a plurality of pressure-sensitive members as described above, the plurality of pressure-sensitive members may be included in a shape in which they are alternately positioned between individual electrode assemblies constituting the plurality of electrode assemblies.

[0056] Figure 2 schematically illustrates a test subject (100b) that is the target of a pressure evaluation method of a battery according to another specific example of the present invention.

[0057] Referring to FIG. 2, the test object (100b) according to one specific example of the present invention further includes a buffer layer (30).

[0058] The buffer layer is intended to facilitate application of the subject to the battery, and any material capable of preventing side reactions that may occur between electrode assemblies may be used in the buffer layer. For example, polymers such as polyurethane (PU) and polytetrafluoroethylene (PTFE), silicon (Si), compounds containing the same, or combinations thereof may be used, but is not limited thereto as long as it is commonly used in the relevant technical field.

[0059] The buffer layer may also have a thickness that does not affect battery operation, and may be included at a thickness that is commonly known in the art.

[0060] In one specific embodiment of the present invention, the buffer layer is located between the all-solid-state battery and the pressure reducing member.

[0061] In one specific example of the present invention, the buffer layer is located on the lower surface of the all-solid-state battery.

[0062] In one specific embodiment of the present invention, the buffer layer is located between the lower surface of the all-solid-state battery and the pressure reducing member.

[0063] When the above buffer layer satisfies the above position, application to the battery can be made easier.

[0064] In one specific example of the present invention, the all-solid-state battery in the subject means an electrode assembly of the all-solid-state battery.

[0065] In one specific embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer.

[0066] The above-mentioned positive electrode current collector is a conductive member that functions as a path for electrons that are emitted from the positive electrode toward an external load or that flow from a power source toward the positive electrode according to a battery reaction.

[0067] The above-described positive electrode current collector may generally have a thickness of 3 μm to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The current collector may also form fine irregularities on its surface to increase the adhesive strength of the positive electrode active material, and may be in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0068] In addition, the above-mentioned positive electrode current collector may have a single-layer structure made of a single material, or may have a laminated structure in which layers made of such materials are appropriately combined. In the case of the current collector for reducing weight, it may include at least a conductive resin layer made of a conductive resin.

[0069] The above positive electrode active material layer may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0070] The above-mentioned positive electrode active material is not particularly limited as long as it is a lithium composite oxide material capable of reversible insertion and de-insertion of lithium ions. For example, it may include at least one of a composite oxide of cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0071] For a more specific example, as the positive electrode active material, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b R b D2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b R b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Co b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Co b R c O 2-αZ2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Mn b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG bO2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); and LiFePO4.

[0072] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z 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; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0073] The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fiber or metal fiber; metal powders such as fluorinated carbon, aluminum, and nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0074] The above binder is a component added in consideration of the binding properties of the positive active material, solid electrolyte, and conductive material included in the positive active material layer, and may be any type of binder as long as it can be used for electrode formation in the technical field to which the present invention pertains. For example, it may be at least one selected from the group consisting of nitrile-butadiene rubber (NBR), polystyrene, and styrene-butadiene rubber (SBR), and preferably, it may be a binder of the butadiene rubber series such as nitrile-butadiene rubber (NBR) or styrene-butadiene rubber (SBR).

[0075] In one specific example of the present invention, the solid electrolyte included in the positive electrode active material layer includes at least one of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and a polymer-based solid electrolyte.

[0076] In one specific example of the present invention, the solid electrolyte includes a sulfide-based solid electrolyte.

[0077] The sulfide-based solid electrolyte included in the above positive electrode active material layer may be, for example, represented by the following chemical formula 1.

[0078] [Chemical Formula 1]

[0079] Li a M b S c X d

[0080] In the above chemical formula 1, M is Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, X is F, Cl, Br, I, Se, Te, or O, and 0 <a≤6, 0<b≤6, 0<c≤6 및 0<d≤6이다.

[0081] For example, in the above chemical formula 1, M can be B, Si, Ge, P or N.

[0082] For example, in the above chemical formula 1, X can be F, Cl, Br, I or O.

[0083] For example, the sulfide-based solid electrolyte represented by the above chemical formula 1 may be Li2S-P2S5-LiBr, Li2S-P2S5-LiCl-LiBr, Li2S-SiS2-LiBr, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-GeS2, Li2S-SiS2-Li3PO4, or a combination thereof.

[0084] The above sulfide-based solid electrolyte may have an argyrodite-type crystal structure. Since the sulfide-based solid electrolyte has an argyrodite-type crystal structure, the purity and crystallinity of the sulfide-based solid electrolyte are high, and a stable interfacial phase is formed, thereby achieving a high energy density while significantly improving potential stability and ionic conductivity.

[0085] Examples of the above oxide-based solid electrolyte include compounds having a NASICON-type structure. An example of a compound having a NASICON-type structure is a compound having the general formula Li 1+xAl x Ge 2-x A compound (LAGP) represented by (PO4) 3 (0 ≤ x ≤ 2), general formula Li 1+x Al x Ti 2-x (PO4) 3 (0 ≤ x ≤ 2) compounds (LATP) can be mentioned. Also, other examples of oxide solid electrolytes include LiLaTiO (e.g., Li 0.34 La 0.51 TiO3), LiPON (e.g. Li 2.9 PO 3.3 N 0.46 ), LiLaZrO (e.g. Li7La3Zr2O 12 ) can be cited.

[0086] Examples of the shape of the above solid electrolyte include particle shapes such as spherical, elliptical, and spherical, and thin film shapes. However, when the shape of the solid electrolyte is particle shape, the average particle diameter may be 0.1 ㎛ to 5 ㎛.

[0087] The above-mentioned positive electrode active material layer can be manufactured according to a method widely known in the art, and is not limited to a specific manufacturing method, but for example, it can be manufactured by a dry electrode process method in which the positive electrode active material, a solid electrolyte, a conductive material, and a binder are mixed to manufacture a dough and then the manufactured dough is sheeted, or a wet process in which the positive electrode mixture is manufactured in a slurry state by mixing in a solvent and then the positive electrode mixture is applied to a positive electrode current collector.

[0088] The above-described positive electrode active material layer may further include additives such as fillers, coating agents, dispersants, and ion-conducting aids in addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder. The fillers, coating agents, dispersants, ion-conducting aids, and the like may be known materials generally used in electrodes of all-solid-state batteries.

[0089] The thickness of the positive electrode active material layer may vary depending on the configuration of the intended all-solid-state battery, but is preferably in the range of 0.1 µm to 1,000 µm, and more preferably 40 µm to 100 µm.

[0090] The above solid electrolyte layer is a layer interposed between the positive electrode and the negative electrode, which contains a solid electrolyte as its main component. The solid electrolyte layer contains a solid electrolyte, and the solid electrolyte may be the same as or different from the solid electrolyte contained in the positive electrode active material layer. Since the specific type thereof is the same as that described for the positive electrode active material layer, a detailed description thereof will be omitted.

[0091] The elastic modulus of the solid electrolyte layer, i.e., Young's modulus, may be, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, or 23 GPa or less. The elastic modulus of the solid electrolyte layer, i.e., Young's modulus, may be, for example, 10 to 35 GPa, 15 to 35 GPa, 15 to 30 GPa, or 15 to 25 GPa. Since the solid electrolyte layer has an elastic modulus in this range, pressurization and / or sintering of the solid electrolyte included in the solid electrolyte layer may be performed more easily.

[0092] The above solid electrolyte layer further includes, for example, a binder. The binder included in the solid electrolyte layer is not limited to, but may include, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., and any binder used in the relevant technical field may be used. The binder of the solid electrolyte layer may be the same as or different from the binder of the positive electrode active material layer.

[0093] The thickness of the solid electrolyte layer may vary depending on the configuration of the intended all-solid-state battery, and from the viewpoint of improving the volumetric energy density of the battery, it may be preferably 600 μm or less, more preferably 500 μm or less or 400 μm or less. Meanwhile, there is no particular limitation on the lower limit of the thickness of the solid electrolyte layer, but it may preferably be 1 μm or more, 5 μm or more, or 10 μm or more.

[0094] The above negative electrode may include a negative electrode active material layer and a negative electrode current collector.

[0095] The above-described negative current collector is a conductive member that functions as a path for electrons that are emitted from the negative electrode toward the power source or that flow into the negative electrode from an external source according to the charge / discharge behavior of the battery. The negative current collector is composed of, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound. The material constituting the negative current collector is, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited thereto, and any material that is used as an electrode current collector in the relevant technical field may be used. The negative current collector may be composed of one type of the above-described metal, or may be composed of an alloy or a coating material of two or more types of metals. The negative current collector is, for example, in the form of a plate or a foil.

[0096] The negative electrode active material layer includes, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0097] The negative active material included in the negative active material layer may have, for example, a particle form.

[0098] The negative electrode active material included in the negative electrode active material layer includes, for example, at least one selected from a carbon-based negative electrode active material and a metal or metalloid negative electrode active material.

[0099] The carbon-based negative electrode active material is, in particular, amorphous carbon. Amorphous carbon includes, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0100] The metal or metalloid negative electrode active material includes, but is not limited to, one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), and any metal or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used. For example, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0101] The negative electrode active material layer includes a type of negative electrode active material among these negative electrode active materials, or includes a mixture of a plurality of different negative electrode active materials. For example, the negative electrode active material layer includes only amorphous carbon, or includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the negative electrode active material layer includes a mixture of amorphous carbon and at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of amorphous carbon and silver (Ag) etc. is a weight ratio, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to this range and is selected according to the characteristics of the required all-solid-state battery.

[0102] The negative active material included in the negative active material layer includes a mixture of first particles made of, for example, amorphous carbon and second particles made of a metal or a metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The metalloid is alternatively a semiconductor. The content of the second particles is 8 wt% to 60 wt%, 10 wt% to 50 wt%, 15 wt% to 40 wt%, or 20 wt% to 30 wt%, based on the total weight of the mixture.

[0103] The negative active material layer includes, for example, a binder. The binder is, but is not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., and any binder used in the art may be used. The binder may be composed of a single binder or a plurality of different binders.

[0104] By including a binder in the negative active material layer, the negative active material layer is stabilized on the negative electrode current collector. Furthermore, cracking of the negative active material layer is suppressed despite changes in the volume and / or relative position of the negative active material layer during charge and discharge processes. For example, if the negative active material layer does not include a binder, it is possible for the negative active material layer to easily separate from the negative electrode current collector. The portion where the negative active material layer separates from the negative electrode current collector is exposed and comes into contact with the solid electrolyte layer, increasing the possibility of a short circuit. The negative active material layer is manufactured, for example, by applying a slurry containing dispersed materials for the negative electrode active material layer onto the negative electrode current collector and drying it. Incorporating a binder into the negative electrode active material layer enables stable dispersion of the negative active material in the slurry. For example, when applying the slurry onto the negative electrode current collector using a screen printing method, it is possible to suppress screen clogging (e.g., clogging by aggregates of the negative electrode active material).

[0105] The above negative electrode may further include additives used in conventional all-solid-state batteries, such as fillers, dispersants, and ionic conductors.

[0106] The above all-solid-state battery can be manufactured by manufacturing the positive electrode, the solid electrolyte layer, and the negative electrode, respectively, and then sequentially stacking them.

[0107] In one embodiment of the present invention, the electrode assemblies stacked in the above order may be structured to be housed in a case such as a pouch. In addition, an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0108] The above pressure sensitive member refers to a material capable of measuring whether pressure is applied and its magnitude. In the present invention, the pressure sensitive member may be of any type as long as it can measure whether pressure is applied to the subject and evaluate the applied pressure. For example, a pressure sensitive paper may be used as the pressure sensitive member.

[0109] In one specific example of the present invention, the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced.

[0110] The above pressure-sensitive paper is a paper that changes color depending on the pressure applied state. If no discolored area appears on the pressure-sensitive paper, it can be known that no pressure is applied to the relevant area. This pressure-sensitive paper has microcapsules and a developer applied to the substrate, so that a certain color develops when pressure is applied. In addition, the color density changes depending on the strength of the pressure, and a darker color appears when higher pressure is applied. Therefore, it can be known that higher pressure is applied to the relevant area by visually confirming that the density of the discolored area on the pressure-sensitive paper is darker. In other words, if the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced, the pressure applied to the subject can be measured based on the color development state of the pressure-sensitive paper.

[0111] There are pressure sensitive papers on the market, such as 'prescale' manufactured by Fujifilm, and depending on the pressure range, it can measure whether the pressure is applied in 7 stages: low pressure between 0.05 MPa and 0.2 MPa, ultra-low pressure between 0.2 MPa and 0.6 MPa, ultra-low pressure between 0.5 MPa and 2.5 MPa, low pressure between 2.5 MPa and 10 MPa, medium pressure between 10 MPa and 50 MPa, high pressure between 50 MPa and 130 MPa, and ultra-high pressure between 130 MPa and 300 MPa.

[0112] Whether or not there is discoloration in the pressure-sensitive member can be measured by visually evaluating the discoloration concentration of the pressure-sensitive member by comparing it with a reference such as a standard color sample, thereby measuring the magnitude of the pressure applied to the subject.

[0113] In one specific example of the present invention, n of the pressure-sensitive members are included in the subject (provided that n is an integer greater than or equal to 1).

[0114] In one specific example of the present invention, the test body includes p solid-state batteries and q pressure sensitive members (provided that p and q are the same as or different from each other and are each independently an integer greater than or equal to 1), and the pressure sensitive member is included between each solid-state battery when the p solid-state batteries are sequentially stacked.

[0115] In one specific example of the present invention, the subject includes m+1 or more pressure sensitive members within the subject when m solid-state batteries (wherein m is an integer greater than or equal to 1) are included within the subject, the subject includes pressure sensitive members on the upper surface and the lower surface, and the pressure sensitive members are included between each solid-state battery when the m solid-state batteries are sequentially stacked.

[0116] An evaluation method according to one specific example of the present invention includes pressure-sensitive members on the upper and lower surfaces of a test body and includes a pressure-sensitive member between all-solid-state batteries, thereby enabling pressure evaluation to be performed on a plurality of all-solid-state batteries, thereby improving the efficiency of the evaluation.

[0117] Next, (step (2)) is a step of pressing the subject in the thickness direction of the all-solid-state battery using a pressing means.

[0118] The specific composition of the above-mentioned subject is the same as that described in step (1) above, so a detailed description thereof will be omitted below.

[0119] The pressurizing means may be any type of means capable of applying pressure to the test object, and for example, a pressurizing means using a device including a hydraulic press, specifically a hand hydraulic press, may be used. A representative example of this is a 'jig' that is mainly used to apply pressure or fastening pressure during the operation process of an all-solid-state battery, and examples of the jig include a spring type jig as in FIG. 5 and a washer type jig as in FIG. 6. In addition, a method such as a warm isostatic press (WIP) as in FIG. 7 may be used as the pressurizing means, and specifically, a test object manufactured by a pressurizing method using a warm isostatic press as in FIG. 7 may be as in FIG. 8.

[0120] In one specific embodiment of the present invention, the pressurizing means is applied by a device including a hydraulic press, a jig, or a warm hydrostatic press. The pressurizing in the thickness direction means applying pressure in a direction perpendicular to the surface on which the all-solid-state battery and the pressure reducing member are laminated.

[0121] In one specific example of the present invention, the ratio (a / b) of the size (a) of the cross-sectional area of ​​the portion of the pressurizing means that comes into contact with the subject during the pressurizing step (2) and the size (b) of the cross-sectional area of ​​the portion of the subject that comes into contact with the pressurizing means is 8:1 or more. Specifically, the ratio (a / b) of the cross-sectional area sizes may be 8:1 or more, 9:1 or more, 10:1 or more, 11:1 or more, 12:1 or more, 13:1 or more, or 14:1 or more. When the ratio (a / b) of the cross-sectional area sizes satisfies the above range, pressurization can be uniformly applied to the entire portion of the subject, and the degree of pressurization can be evaluated even with a low pressurizing pressure.

[0122] The ratio of the cross-sectional area sizes (a / b) above can achieve uniform pressurization if it is 8:1 or more, and in consideration of cases where the pressurization of multiple test subjects is evaluated, it can have a value significantly greater than 8:1. However, in consideration of economic aspects for commercial use, the ratio of the cross-sectional area sizes (a / b) can be 100:1 or less. Specifically, it can be 100:1 or less, 90:1 or less, 80:1 or less, 70:1 or less, 60:1 or less, 50:1 or less, 40:1 or less, 30:1 or less, or 20:1 or less.

[0123] Figure 3 is a schematic diagram showing the contact state between a pressurizing means and a subject during pressurization according to one specific example of the present invention.

[0124] Referring to FIG. 3, the size (a) of the cross-sectional area of ​​the portion of the pressurizing means (200) that comes into contact with the subject (100) refers to the area of ​​the surface of the pressurizing means (200) that comes into contact with the subject (100), and the size (b) of the cross-sectional area of ​​the portion of the subject (100) that comes into contact with the pressurizing means (200) refers to the area of ​​the surface of the subject (100) that comes into contact with the pressurizing means (200).

[0125] In one specific example of the present invention, the pressure applied in the step (2) for the evaluation is 0.05 MPa to 10 MPa. Specifically, it is 0.05 MPa or more, 0.1 MPa or more, 0.5 MPa or more, 1 MPa or more, 1.5 MPa or more, or 2 MPa or more, and 10 MPa or less, 9.5 MPa or less, 9 MPa or less, 8.5 MPa or less, 8 MPa or less, 7.5 MPa or less, 7 MPa or less, 6.5 MPa or less, 6 MPa or less, 5.5 MPa or less, 5 MPa or less, 4.5 MPa or less, 4 MPa or less, 3.5 MPa or less, 3 MPa or less, or 2.5 MPa or less, and may be 0.05 MPa to 10 MPa, 1 MPa to 8 MPa, or 1 MPa to 6 MPa.

[0126] An evaluation method according to one specific embodiment of the present invention can uniformly pressurize a test subject even with a small amount of pressure, thereby enabling evaluation of the degree of pressurization even with a small amount of pressure. When the pressure satisfies the above range, the efficiency and economic feasibility of the evaluation can be improved.

[0127] Next, (step (3)) image information of the pressure reducing member is acquired after the pressurization type of step (2), and (step (4)) the pressure distribution of the all-solid-state battery is determined from the acquired image information of the pressure reducing member.

[0128] In the above-mentioned test object, the pressure applied vertically to the pressure-sensitive member located on at least one side of the all-solid-state battery is transmitted as a visual image through the pressure-sensitive member, and through the visual image, the pressure information about the pressure applied to the pressure-sensitive member and further to the all-solid-state battery located adjacent thereto can be obtained through the image. That is, the pressure evaluation method of the all-solid-state battery according to the present invention has the advantage of easy pressure evaluation because the process of obtaining information about the intensity and uniformity of the pressure applied to the all-solid-state battery through the degree of discoloration, the area of ​​discoloration, and the distribution of the discolored portion in the pressure-sensitive member is transmitted as visual image information using the pressure-sensitive member included in the test object, and is convenient in that no separate power source is required for the pressure evaluation and the size can be adjusted and used depending on the size of the test object.

[0129] In one specific example of the present invention, the step of acquiring image information of the pressure-sensitive member in step (3) is to acquire information on the intensity of pressure applied to the all-solid-state battery and the uniformity of pressure through the degree of discoloration, the discolored area, and the distribution of the discolored portion in the pressure-sensitive member.

[0130] In one specific example of the present invention, when the subject includes n pressure-sensitive members (provided that n is an integer greater than or equal to 1), the image information of the pressure-sensitive members of the step (3) is, when n is an even number and is the image information of the (n / 2)-th or (n / 2)+1-th pressure-sensitive member when n pressure-sensitive members are sequentially stacked, and is the image information of the (n+1) / 2-th pressure-sensitive member when n is an odd number. For example, when the subject includes 8 pressure-sensitive members, which is an even number, the image information of the pressure-sensitive member may be the image information of the (n / 2)-th or (n / 2)+1-th pressure-sensitive member, which is the 4th position in the stacking order, or the image information of the 5th pressure-sensitive member, which is the 5th position in the stacking order. Alternatively, when the subject includes 9 pressure-sensitive members, which is an odd number, the image information of the pressure-sensitive member may be the image information of the (n+1) / 2-th pressure-sensitive member, which is the 5th position in the stacking order.

[0131] That is, in the pressure evaluation method of an all-solid-state battery according to the present invention, when the subject includes a plurality of pressure-sensitive members, by obtaining image information of the pressure-sensitive member located at the innermost position based on the stacking order of the plurality of pressure-sensitive members, it is possible to confirm and evaluate whether the pressure applied through the pressure means can be completely transmitted to the inside of the all-solid-state battery, and thus the image information of the pressure-sensitive member can be utilized to improve the interface characteristics between the positive electrode active material and the solid electrolyte, which can directly affect the operation and life characteristics of the all-solid-state battery.

[0132] In one specific example of the present invention, the step of determining the pressure distribution of the all-solid-state battery from the image information of the pressure-sensitive member obtained in step (4) is to obtain color information for each of a plurality of unit inspection areas within the image of the pressure-sensitive member, calculate an average value thereof, and compare the average value with a standard color sample of the pressure-sensitive member to determine the pressure distribution of the all-solid-state battery.

[0133] Even when pressure is applied through a pressurizing means, there may be cases where the same pressure is not applied based on the entire area of ​​the pressure-sensitive member. In this case, in the pressure evaluation method of the all-solid-state battery according to the present invention, the pressure-sensitive member that has gone through the pressurizing process of step (2) is divided into a plurality of arbitrary unit inspection areas, the color image information of each divided individual area is acquired, the average value is calculated, and the calculated average value is compared with a reference such as a standard color sample to determine the pressure distribution of the all-solid-state battery according to the acquired image information.

[0134] In one specific example of the present invention, before the pressurization in step (2), an elastic member is further included on at least one of the upper or lower surfaces of the subject in step (1).

[0135] The above elastic member may be expressed as a reinforcing material, a buffer layer, or an elastic layer, and serves to ensure that the pressure applied to the electrode assembly including the all-solid-state battery is uniformly transmitted, thereby ensuring good contact between solid components included in the all-solid-state battery, and to ensure that uniform pressure is applied to the pressure-sensitive member capable of acquiring image information by externally applied pressure. Any one of polytetrafluoroethylene (PTFE), silicone, organic rubber, polyurethane, polystyrene, polyethylene, polypropylene, ethylene vinyl acetate (EVA), and polyethylene terephthalate (PET) may be used as the material of the above elastic member, but is not limited to these examples.

[0136]

[0137] Pressure evaluation device for all-solid-state batteries

[0138] The present invention also provides a pressure evaluation device for an all-solid-state battery.

[0139] In one specific example of the present invention, the pressure evaluation device of the all-solid-state battery is a pressure evaluation device of the all-solid-state battery, including a test body having a pressure-sensitive member positioned on at least one of the upper surface or the lower surface of the all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, and a pressure applying means for applying pressure to the test body and providing image information to the pressure-sensitive member so as to confirm the pressure distribution.

[0140] The positive electrode, negative electrode, and solid electrolyte layer of the all-solid-state battery included in the above-mentioned test object, and the pressure-sensitive member are the same as those described in the pressure evaluation method of the all-solid-state battery, so a detailed description thereof will be omitted.

[0141] In one specific embodiment of the present invention, the test body further includes a buffer layer.

[0142] The buffer layer is intended to facilitate application of the subject to the battery, and any material capable of preventing side reactions that may occur between electrode assemblies may be used in the buffer layer. For example, polymers such as polyurethane (PU) and polytetrafluoroethylene (PTFE), silicon (Si), compounds containing the same, or combinations thereof may be used, but is not limited thereto as long as it is commonly used in the relevant technical field.

[0143] The buffer layer may also have a thickness that does not affect battery operation, and may be included at a thickness that is commonly known in the art.

[0144] In one specific embodiment of the present invention, the buffer layer is located between the all-solid-state battery and the pressure reducing member.

[0145] In one specific example of the present invention, the buffer layer is located on the lower surface of the all-solid-state battery.

[0146] In one specific embodiment of the present invention, the buffer layer is located between the lower surface of the all-solid-state battery and the pressure reducing member.

[0147] When the above buffer layer satisfies the above position, application to the battery can be made easier.

[0148] In one specific example of the present invention, the all-solid-state battery in the subject means an electrode assembly of the all-solid-state battery.

[0149] The pressurizing means for applying pressure to the above-mentioned subject may be any type of means capable of applying pressure to the above-mentioned subject, and for example, a pressurizing means using a device including a hydraulic press, specifically a hand hydraulic press, may be used. A representative example of this is a 'jig' that is mainly used to apply pressure or fastening pressure during the operation process of an all-solid-state battery, and examples of the jig include a spring type jig as in FIG. 5 and a washer type jig as in FIG. 6. In addition, a method such as a warm isostatic press (WIP) as in FIG. 7 may be used as the pressurizing means, and specifically, a subject manufactured by a pressurizing method using a warm isostatic press as in FIG. 7 may be as in FIG. 8.

[0150] In one specific embodiment of the present invention, the pressurizing means is a device including a hydraulic press, a jig or a warm hydrostatic press.

[0151] In one specific example of the present invention, the pressure applied to the subject is applied in the thickness direction of the all-solid-state battery. The pressure applied in the thickness direction means applying pressure in a direction perpendicular to the surface on which the all-solid-state battery and the pressure-sensitive member are laminated.

[0152] In one specific example of the present invention, when pressure is applied to the subject, the ratio (a / b) of the size of the cross-sectional area of ​​the portion of the pressurizing means that comes into contact with the subject and the size of the cross-sectional area of ​​the portion of the subject that comes into contact with the pressurizing means is 8:1 or more. Specifically, the ratio (a / b) of the cross-sectional area sizes may be 8:1 or more, 9:1 or more, 10:1 or more, 11:1 or more, 12:1 or more, 13:1 or more, or 14:1 or more. When the ratio (a / b) of the cross-sectional area sizes satisfies the above range, pressurization can be uniformly applied to the entire portion of the subject, and the degree of pressurization can be evaluated even with a low pressurization pressure.

[0153] The ratio of the cross-sectional area sizes (a / b) above can achieve uniform pressurization if it is 8:1 or more, and in consideration of cases where the pressurization of multiple test subjects is evaluated, it can have a value significantly greater than 8:1. However, in consideration of economic aspects for commercial use, the ratio of the cross-sectional area sizes (a / b) can be 100:1 or less. Specifically, it can be 100:1 or less, 90:1 or less, 80:1 or less, 70:1 or less, 60:1 or less, 50:1 or less, 40:1 or less, 30:1 or less, or 20:1 or less.

[0154] In the above-mentioned subject, the pressure applied vertically to the pressure-sensitive member located on at least one side of the all-solid-state battery is transmitted as a visual image through the pressure-sensitive member, and through the visual image, the pressure applied to the pressure-sensitive member and further to the all-solid-state battery located adjacent thereto can be obtained through the image, and pressure distribution information can be obtained. That is, the pressure evaluation device of the all-solid-state battery according to the present invention has the advantage of easy pressure evaluation because the process of obtaining information on the intensity and uniformity of the pressure applied to the all-solid-state battery through the degree of discoloration, the area of ​​discoloration, and the distribution of the discolored portion in the pressure-sensitive member is transmitted as visual image information using the pressure-sensitive member included in the subject, and a separate power source is not required for the pressure evaluation, and the device is convenient in that the size can be adjusted and used according to the size of the subject.

[0155] In one specific example of the present invention, the pressure evaluation device obtains information on the intensity and uniformity of the pressure applied to the all-solid-state battery through the degree of discoloration, the discolored area, and the distribution of the discolored portion in the pressure-sensitive member for evaluation.

[0156] In one specific example of the present invention, the pressure-sensitive member is included in the subject n times (provided that n is an integer greater than or equal to 1). For example, when n pressure-sensitive members are sequentially stacked, the image information of the pressure-sensitive member may be image information of the (n / 2)-th or (n / 2)+1-th positioned pressure-sensitive member when n is an even number, and may be image information of the (n+1) / 2-th positioned pressure-sensitive member when n is an odd number. Specifically, when the subject includes an even number of 8 pressure-sensitive members, the image information of the pressure-sensitive member may be image information of the (n / 2)-th or (n / 2)+1-th pressure-sensitive member, which is the 4th position in the stacking order, or the 5th positioned pressure-sensitive member. Alternatively, when the subject includes an odd number of 9 pressure-sensitive members, the image information of the pressure-sensitive member may be image information of the (n+1) / 2-th pressure-sensitive member, which is the 5th position in the stacking order.

[0157] That is, in a case where the subject of the pressure evaluation device of the all-solid-state battery according to the present invention includes a plurality of pressure-sensitive members, by acquiring image information of the pressure-sensitive member located at the innermost position based on the stacking order of the plurality of pressure-sensitive members, it is possible to confirm and evaluate whether the pressure applied through the pressure means can be completely transmitted to the inside of the all-solid-state battery, and thus the image information of the pressure-sensitive member can be utilized to improve the interface characteristics between the positive electrode active material and the solid electrolyte, which can directly affect the operation and life characteristics of the all-solid-state battery.

[0158] In one specific example of the present invention, the test body includes p solid-state batteries and q pressure sensitive members (provided that p and q are the same as or different from each other and are each independently an integer greater than or equal to 1), and the pressure sensitive member is included between each solid-state battery when the p solid-state batteries are sequentially stacked.

[0159] In one specific example of the present invention, the subject includes m+1 or more pressure sensitive members within the subject when m solid-state batteries (wherein m is an integer greater than or equal to 1) are included within the subject, the subject includes pressure sensitive members on the upper surface and the lower surface, and the pressure sensitive members are included between each solid-state battery when the m solid-state batteries are sequentially stacked.

[0160] An evaluation device according to one specific example of the present invention includes pressure-sensitive members on the upper and lower surfaces of a test body and includes a pressure-sensitive member between all-solid-state batteries, thereby enabling pressure evaluation to be performed on a plurality of all-solid-state batteries, thereby improving the efficiency of the evaluation.

[0161] In one specific example of the present invention, the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced.

[0162] The above pressure-sensitive paper is a paper that changes color depending on the pressure applied state. If no discolored area appears on the pressure-sensitive paper, it can be known that no pressure is applied to the relevant area. This pressure-sensitive paper has microcapsules and a developer applied to the substrate, so that a certain color develops when pressure is applied. In addition, the color density changes depending on the strength of the pressure, and a darker color appears when higher pressure is applied. Therefore, it can be known that higher pressure is applied to the relevant area by visually confirming that the density of the discolored area on the pressure-sensitive paper is darker. In other words, if the pressure-sensitive member is a pressure-sensitive paper that develops color when pressure is reduced, the pressure applied to the subject can be measured based on the color development state of the pressure-sensitive paper.

[0163] There are pressure sensitive papers on the market, such as 'prescale' manufactured by Fujifilm, and depending on the pressure range, it can measure whether the pressure is applied in 7 stages: low pressure between 0.05 MPa and 0.2 MPa, ultra-low pressure between 0.2 MPa and 0.6 MPa, ultra-low pressure between 0.5 MPa and 2.5 MPa, low pressure between 2.5 MPa and 10 MPa, medium pressure between 10 MPa and 50 MPa, high pressure between 50 MPa and 130 MPa, and ultra-high pressure between 130 MPa and 300 MPa.

[0164] Whether or not there is discoloration in the pressure-sensitive member can be measured by visually evaluating the discoloration concentration of the pressure-sensitive member by comparing it with a reference such as a standard color sample, thereby measuring the magnitude of the pressure applied to the subject.

[0165] In one specific embodiment of the present invention, an elastic member may be further included on at least one of the upper or lower surfaces of the subject.

[0166] The above elastic member may be expressed as a reinforcing material, a buffer layer, or an elastic layer, and serves to ensure that the pressure applied to the electrode assembly including the all-solid-state battery is uniformly transmitted, thereby ensuring good contact between solid components included in the all-solid-state battery, and to ensure that uniform pressure is applied to the pressure-sensitive member capable of acquiring image information by externally applied pressure. Any one of polytetrafluoroethylene (PTFE), silicone, organic rubber, polyurethane, polystyrene, polyethylene, polypropylene, ethylene vinyl acetate (EVA), and polyethylene terephthalate (PET) may be used as the material of the above elastic member, but is not limited to these examples.

[0167] Below, specific embodiments of the present invention are presented. However, the embodiments described below are intended solely to specifically illustrate or explain the present invention and are not intended to limit the scope of the invention. Furthermore, any details not described herein are technically feasible to those skilled in the art and thus are omitted.

[0168]

[0169] Manufacturing example: Manufacturing of a test specimen for pressurization evaluation of an all-solid-state battery

[0170] (1) Manufacturing of anode

[0171] Based on 100 parts by weight of the total positive electrode layer, LiNi having a particle size (D50) of 5 ㎛ as the positive electrode active material 0.8 Co 0.1 Mn 0.1 78 parts by weight of O2 powder, 19.5 parts by weight of lithium argyrodite-type solid electrolyte Li6PS5Cl, 1.5 parts by weight of carbon black conductive agent, and 1.0 parts by weight of styrene-butadiene rubber (SBR) binder are added to a xylene solvent, 2 mm zirconia balls are added, and a slurry is prepared by stirring with a sinky mixer.

[0172] The manufactured slurry is applied to one side of an aluminum current collector having a thickness of 15 ㎛, which is a positive electrode collector, and dried in a vacuum oven at 100°C for 8 hours to prepare a positive electrode of an all-solid-state battery.

[0173] (2) Manufacturing of solid electrolyte layer

[0174] A lithium argyrodite-type solid electrolyte Li6PS5Cl is added to a binder solution in which an acrylic binder (SX-A334, manufactured by Zeon) is dissolved in an isobutyl isobutyrate (IBIB) solvent, and the solution is stirred in a sinky mixer to adjust the viscosity to an appropriate level. After adjusting the viscosity, 2 mm zirconia balls are added and stirred again in a sinky mixer to prepare a slurry. The slurry contains 98.5 wt% of the solid electrolyte and 1.5 wt% of the binder. The slurry is applied on a release PET film using a bar coater and dried at room temperature to prepare a solid electrolyte layer.

[0175] (3) Manufacturing of all-solid-state battery electrode assembly

[0176] The prepared positive electrode and solid electrolyte layer are cut together, and lithium metal with a thickness of 100 ㎛ is used as the negative electrode, and the positive electrode, solid electrolyte layer, and negative electrode current collector are laminated in that order, then sealed in a pouch shape and subjected to a warm isostatic press (WIP) at a high temperature of 80°C and 500 MPa for 30 minutes to manufacture an all-solid-state battery electrode assembly. In a pressurized state, the thickness of the positive electrode is about 100 ㎛, the thickness of the negative electrode is about 100 ㎛, and the thickness of the solid electrolyte layer is about 60 ㎛.

[0177] (4) Preparation of pressure evaluation specimens

[0178] A 0.2 mm thick polyurethane (PU) pad is used as a buffer layer, and a pressure-sensitive member is used as a pressure-sensitive member (Prescale manufactured by Fujifilm). TM, for Low Pressure) is punched out to 18 mm × 18 mm, and the lower surface of the manufactured electrode assembly is positioned in the order of a buffer layer and a pressure-sensitive member to manufacture one set of 'all-solid-state battery electrode assembly-buffer layer-pressure-sensitive paper'. The three sets of 'all-solid-state battery electrode assembly-buffer layer-pressure-sensitive paper' are prepared, and these are placed in a laminate-type pouch and vacuum-sealed to -100 kPa to manufacture a test subject for pressure evaluation. The test subject for pressure evaluation manufactured as described above is shown in Fig. 4.

[0179]

[0180] Example 1: Pressure evaluation of all-solid-state batteries (1)

[0181] The pressure evaluation specimen manufactured in the above manufacturing example is installed in a jig cell, and pressures of 2.5 MPa, 5.0 MPa, and 7.5 MPa are applied in the thickness direction of the specimen, as shown in Fig. 9, using a pressurizing means of 1) pressurizing using a torque wrench, and 2) pressurizing by applying hydraulic pressure to the jig cell. The method 1) is a method in which a fixed jig plate made of aluminum is positioned on the upper and lower parts of the specimen, and a torque wrench is used to pressurize bolts / nuts located at the square corners of the fixed jig plate, and the method 2) is a method in which the fixed jig plates located on the upper and lower parts of the specimen are directly pressurized by hydraulic pressure.

[0182] The above specimen was installed inside a jig cell after positioning a 0.2 mm thick polyurethane (PU) pad as an elastic member on the upper and lower surfaces of the specimen.

[0183] The pouch of the subject subjected to pressure application is disassembled to obtain image information based on the color change of the internal pressure sensitive paper, and then compared with a standard color sample to determine the pressure distribution applied to the all-solid-state battery. The results are shown in Fig. 9.

[0184] Referring to Fig. 9, when pressure is applied to the subject by '1) applying pressure using a torque wrench', the color of the chromogenic paper changes only when a relatively high pressure of 5.0 MPa or higher is applied, and it can be seen that the pressure is not applied uniformly even when a pressure of 7.5 MPa is applied. In contrast, when pressure is applied to the subject by '2) applying pressure by applying hydraulic pressure to the jig cell', it can be seen that pressure is applied to the subject even at a relatively low pressure (2.5 MPa), and it can be confirmed that the pressure is applied uniformly in both the area direction and the thickness direction of the subject.

[0185]

[0186] Example 2: Pressure evaluation of all-solid-state batteries (2)

[0187] The pressure evaluation specimen manufactured in the above manufacturing example is installed in two jig cells (a first jig cell and a second jig cell) each including fixed jig plates of different areas, and pressure is applied in the thickness direction of the specimen. The fixed jig plate of the first jig cell has an area of ​​770% of the area of ​​the specimen, and the fixed jig plate of the second jig cell has an area of ​​1,480% of the area of ​​the specimen.

[0188] The pouch of each subject after pressure application is disassembled to obtain image information based on the color change of the internal pressure sensitive paper, and then this is compared with a standard color sample to determine the pressure distribution applied to the all-solid-state battery. The results are shown in Fig. 10.

[0189] Referring to Fig. 10, when pressure is applied to the subject by the '1) first jig cell', it can be seen that a relatively high pressure is applied to the pressure-sensitive paper located at the upper part of the subject, and the applied pressure is not effectively transmitted to the pressure-sensitive paper located at the lower part of the subject. In addition, when pressure is applied to the subject by using the '1) first jig cell', which is relatively smaller in size than the '2) second jig cell', it can be seen that it is difficult to apply a relatively low pressure of 5 MPa.

[0190] On the other hand, when pressure is applied to the subject using the '2) second jig cell', it can be confirmed that uniform pressure is applied in the area direction and thickness direction of the subject at both relatively high and low pressures.

[0191]

[0192] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0193]

[0194] [Explanation of symbols]

[0195] 10: Decompression member

[0196] 20: Electrode assembly

[0197] 30: Buffer layer

[0198] 50: Exterior material

[0199] 100: Subject

[0200] 100a: Subject according to one specific example of the present invention

[0201] 100b: Subject according to another specific example of the present invention

[0202] 200: Pressurizing means

Claims

1. A method for evaluating the pressure of an all-solid-state battery containing a solid electrolyte, (1) A step of manufacturing a test subject by positioning a pressure-sensitive member on at least one of the upper surface or the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode; (2) A step of pressurizing the above-mentioned subject in the thickness direction of the all-solid-state battery using a pressurizing means; (3) a step of obtaining image information of a decompression member after the pressurization in step (2) is completed; and (4) A step of determining the pressure distribution of the all-solid-state battery from the image information of the pressure reducing member obtained above; A method for evaluating the pressure of an all-solid-state battery including a 2. In paragraph 1, The step of obtaining image information of the pressure-reducing member of step (3) above is: Information about the intensity of pressure applied to the all-solid-state battery and the uniformity of pressure is obtained through the degree of discoloration, the discolored area, and the distribution of the discolored portion in the above-mentioned pressure-reducing member. A method for evaluating the pressurization of an all-solid-state battery.

3. In paragraph 1, The step of determining the pressure distribution of the all-solid-state battery from the image information of the pressure reducing member obtained in the above step (4) is as follows. Obtain color information for each of multiple unit inspection areas within the image of the above pressure-sensitive member and calculate the average value, The pressure distribution of the all-solid-state battery is determined by comparing the above average value with the standard color sample of the above pressure reducing member. A method for evaluating the pressurization of an all-solid-state battery.

4. In paragraph 1, The above pressure reducing member is included in n of the above test body (wherein n is an integer greater than or equal to 1). A method for evaluating the pressurization of an all-solid-state battery.

5. In paragraph 1, The above-mentioned subject comprises p solid-state batteries and q pressure-sensitive elements (wherein p and q are the same or different from each other and are each independently an integer greater than or equal to 1), When the above p solid-state batteries are sequentially stacked, the pressure reducing member is included between each solid-state battery. A method for evaluating the pressurization of an all-solid-state battery.

6. In paragraph 1, The above pressure-sensitive member is a pressure-sensitive paper that develops color by being pressure-sensitive, It measures the pressure applied to the subject based on the color development state of the above pressure sensitive paper. A method for evaluating the pressurization of an all-solid-state battery.

7. In paragraph 1, The above pressurizing means is carried out by a device including a hydraulic press, a jig or a warm hydrostatic press. A method for evaluating the pressurization of an all-solid-state battery.

8. In paragraph 1, Before pressurizing in step (2), an elastic member is further included on at least one of the upper or lower surfaces of the subject in step (1). A method for evaluating the pressurization of an all-solid-state battery.

9. In paragraph 1, In the pressurization step (2) above, the ratio (a / b) of the size of the cross-sectional area of ​​the part of the pressurizing means that comes into contact with the test object and the size of the cross-sectional area of ​​the part of the test object that comes into contact with the pressurizing means is 8:1 or more. A method for evaluating the pressurization of an all-solid-state battery.

10. A test body having a pressure-sensitive member positioned on at least one of the upper surface or the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode; and A pressurizing means for applying pressure to the above-mentioned subject and providing image information so as to confirm the pressure distribution in the above-mentioned pressure-sensitive member; A pressurization evaluation device for an all-solid-state battery including a 11. In Article 10, The pressure applied to the above-mentioned subject is applied in the thickness direction of the above-mentioned all-solid-state battery. A pressurization evaluation device for an all-solid-state battery.

12. In Article 10, The above pressure reducing member is included in n of the above test body (wherein n is an integer greater than or equal to 1). A pressurization evaluation device for an all-solid-state battery.

13. In Article 10, The above pressure-sensitive member is a pressure-sensitive paper that develops color by being pressure-sensitive. A pressurization evaluation device for an all-solid-state battery.

14. In Article 10, The pressurizing means is a device including a hydraulic press, a jig or a warm hydrostatic press. A pressurization evaluation device for an all-solid-state battery.

15. In Article 10, At least one of the upper or lower surfaces of the above-mentioned subject further comprises an elastic member. A pressurization evaluation device for an all-solid-state battery.

Images