Method and apparatus for evaluating pressurization of all-solid-state batteries

Abstract

The present invention relates to a method for evaluating pressure applied to an all-solid-state battery, the method including: (1) a step of preparing a test specimen by positioning a pressure-sensitive member on at least one of the upper and lower surfaces of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; (2) a step of applying pressure to the test specimen in the thickness direction of the all-solid-state battery; (3) a step of obtaining image information of the pressure-sensitive member after completion of the pressure application in step (2); and (4) a step of determining a pressure distribution in the all-solid-state battery from the obtained image information of the pressure-sensitive member; and a pressure evaluation device for evaluating pressure applied to the test specimen and the pressure-sensitive member, the device including a pressure applying means for applying image information to the test specimen and the pressure-sensitive member so that the pressure distribution can be confirmed.

Description

[Technical Field]

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

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0190035, filed December 22, 2023, and Korean Patent Application No. 10-2024-0170546, filed November 26, 2024, and includes all of the contents disclosed in the documents of said Korean patent application as part of the specification. [Background technology]

[0003] Lithium secondary batteries have been mainly used in small devices such as mobile devices and laptops, but in recent years, research into them has expanded to medium and large devices such as energy storage systems (ESS) and electric vehicles (EV).

[0004] Unlike small-sized batteries, medium- to large-sized lithium secondary batteries are subject to harsh operating environments (e.g., temperature and impact) and require the use of more batteries, so they must be safe along with excellent performance and reasonable prices.

[0005] Most currently commercially available lithium secondary batteries use organic liquid electrolytes in which lithium salts are dissolved in flammable organic solvents, which poses potential risks of leakage, fire, and explosion. Therefore, the use of solid electrolytes instead of organic liquid electrolytes has been attracting attention as an alternative to overcome these safety issues.

[0006] Lithium secondary batteries using solid electrolytes have the advantages of increased battery safety, the prevention of electrolyte leakage, improved battery reliability, and the ease of fabricating thin batteries. Furthermore, because lithium metal can be used in the anode, the energy density can be improved. This makes them attractive for applications in compact secondary batteries as well as high-capacity secondary batteries for electric vehicles, and they are attracting attention as next-generation batteries.

[0007] However, lithium secondary batteries using solid electrolytes have lower ionic conductivity than liquid electrolytes, resulting in decreased output characteristics, especially at low temperatures. Furthermore, solid electrolytes have lower surface adhesion to active materials than liquid electrolytes, and the volume of the active materials expands during charge and discharge, increasing interface resistance. Since the active materials are distributed in the solid electrolyte without contacting the electrode active materials, there are problems with output and capacity characteristics being lower than the amount of conductive material added.

[0008] Furthermore, even in the case of lithium secondary batteries using solid electrolytes, the generation of lithium dendrites is unavoidable during the charge and discharge process of the battery, and the dendritic lithium dendrites grow by penetrating the solid electrolyte, which may cause reversible lithium loss and short-circuiting of the battery, and is therefore considered to be a factor that adversely affects the life of the lithium secondary battery.

[0009] To solve this problem, a "pressure process" is performed to apply an external force during the operation of a lithium secondary battery using a solid electrolyte. However, it is currently difficult to easily check whether pressure is being applied uniformly over the entire area of ​​the battery. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-172984 Summary of the Invention [Problem to be solved by the invention]

[0011] An object of the present invention is to provide a method for evaluating a pressure applied to an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode, the method comprising: positioning a pressure-sensitive member on the all-solid-state battery; applying pressure to the all-solid-state battery; and determining a pressure distribution in the all-solid-state battery through image information of the pressure-sensitive member obtained by the pressure application.

[0012] Another object of the present invention is to provide an apparatus for evaluating pressure on an all-solid-state battery, the apparatus including a test object including an all-solid-state battery in which the pressure-sensitive member is located, and a pressure means for applying image information to the pressure-sensitive member so that pressure distribution can be confirmed. [Means for solving the problem]

[0013] A first aspect of the present invention provides a method for evaluating an all-solid-state battery containing a solid electrolyte under pressure, the method comprising: (1) a step of preparing a test specimen by positioning a pressure-sensitive member on at least one of the upper surface and the lower surface of an all-solid-state battery containing a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; (2) a step of applying pressure to the test specimen in the thickness direction of the all-solid-state battery using a pressure means; (3) a step of acquiring image information of the pressure-sensitive member after completion of the pressure application in the step (2); and (4) a step of determining a pressure distribution in the all-solid-state battery from the acquired image information of the pressure-sensitive member.

[0014] In one embodiment of the present invention, the step (3) of acquiring image information of the pressure-sensitive member includes acquiring information on the strength and uniformity of pressure applied to the all-solid-state battery through the degree of discoloration of the pressure-sensitive member, the discolored area, and the distribution of the discolored areas.

[0015] In one embodiment of the present invention, the step of determining the pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member in step (4) includes obtaining color information for each of a plurality of unit inspection areas in the image of the pressure-sensitive member, calculating an average value thereof, and comparing the average value with a standard color sample of the pressure-sensitive member to determine the pressure distribution of the all-solid-state battery.

[0016] In one embodiment of the present invention, the subject includes n pressure-sensitive members (where n is an integer of 1 or more).

[0017] In one embodiment of the present invention, the test subject includes p all-solid-state batteries and q pressure-sensitive members (where p and q are the same or different and each independently represents an integer of 1 or more), and the pressure-sensitive members are included between each of the p all-solid-state batteries, based on the time when the p all-solid-state batteries are sequentially stacked.

[0018] In one embodiment of the present invention, the pressure-sensitive member is pressure-sensitive paper that changes color when it is subjected to pressure, and the pressure applied to the subject is measured based on the color change state of the pressure-sensitive paper.

[0019] In one embodiment of the present invention, the pressing is performed by a device including a hydraulic press, a jig, or a warm isostatic press.

[0020] In one embodiment of the present invention, an elastic member is further included on at least one of the upper and lower surfaces of the subject in step (1) before the pressure is applied in step (2).

[0021] In one embodiment of the present invention, when pressurizing in step (2), the ratio (a / b) of the cross-sectional area (a) of the portion of the pressurizing means that comes into contact with the specimen to the cross-sectional area (b) of the portion of the specimen that comes into contact with the pressurizing means is 8:1 or more.

[0022] A second aspect of the present invention provides a pressure evaluation device for an all-solid-state battery, including: an object to be tested, in which a pressure-sensitive member is located 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 located between the positive electrode and the negative electrode; and pressure means for applying pressure to the object to provide image information on the pressure-sensitive member so that pressure distribution can be confirmed.

[0023] In one embodiment of the present invention, the pressure applied to the subject is applied in a thickness direction of the all-solid-state battery.

[0024] In one embodiment of the present invention, the subject includes n pressure-sensitive members (where n is an integer of 1 or more).

[0025] In one embodiment of the present invention, the pressure-sensitive member is pressure-sensitive paper that changes color when exposed to pressure.

[0026] In one embodiment of the present invention, the pressing means is an apparatus including a hydraulic press, a jig or a warm isostatic press.

[0027] In one embodiment of the present invention, the subject further includes an elastic member on at least one of the upper and lower surfaces. [Effects of the Invention]

[0028] According to the present invention, by obtaining pressure information applied to an all-solid-state battery through image information on a pressure member obtained in a pressure evaluation method for an all-solid-state battery, it is possible to confirm and visualize the degree of clamping pressure applied to the all-solid-state battery in the surface direction or thickness direction, thereby obtaining information that can be used to determine a method of applying clamping pressure to the 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. Another advantage is that a pressure evaluation device including a test object including an all-solid-state battery and a pressure means can easily confirm the pressure applied to the all-solid-state battery through the pressure means through image information of a pressure-sensitive member. [Brief explanation of the drawings]

[0029] [Figure 1] 1 is a schematic diagram showing a subject of a pressure evaluation method according to an embodiment of the present invention; [Figure 2] FIG. 10 is a schematic diagram showing a subject in a pressure evaluation method according to another embodiment of the present invention. [Figure 3]1 is a schematic diagram showing a contact state between a pressure applying means and a test object when pressure is applied according to an embodiment of the present invention. [Figure 4] 1 is a photograph showing a subject in a pressure evaluation method according to an embodiment of the present invention. [Figure 5] 1 is a photograph showing a pressure means according to one embodiment of the present invention. [Figure 6] 1 is a photograph showing a pressure means according to one embodiment of the present invention. [Figure 7] 1 is a photograph showing a pressure means according to one embodiment of the present invention. [Figure 8] 8 is a photograph showing a subject to which pressure is applied according to the pressure applying means of FIG. 7. [Figure 9] FIG. 10 is a diagram showing image information of a pressure-sensitive member to which pressure is applied in accordance with one embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing image information of a pressure-sensitive member to which pressure is applied in accordance with one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms and phrases used in the specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that correspond to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term in order to best describe his or her invention. Therefore, it should be understood that the configurations described in the examples described in this specification are merely the most preferred embodiments of the present invention and do not fully represent the technical idea of ​​the present invention, and therefore, various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] In this specification, when a part is said to "comprise" a certain component, this means that it can further include other components, rather than excluding other components, unless otherwise specified.

[0032] In this specification, descriptions that limit or add specific elements can be applied to all inventions unless otherwise specified, and are not limited to a specific invention.

[0033] Herein, throughout the description and claims of this application, the singular includes the plural unless otherwise stated.

[0034] Throughout this specification, throughout the description of the invention and claims of this application, "or" includes "and" unless otherwise stated. Thus, "including A or B" means all three cases: including A, including B, or including A and B.

[0035] In this specification, when a structure is "above" or "below" another structure, it does not only mean that the structure is in direct contact with the other structure and is located on the upper or lower side, but also means that there is another structure between the structure and the other structure.

[0036] All numerical ranges herein include the endpoints and all intermediate values ​​therebetween unless expressly stated to the contrary.

[0037] Pressurization evaluation method for all-solid-state batteries The present invention provides a method for evaluating an all-solid-state battery under pressure.

[0038] Hereinafter, the method for evaluating the pressure applied to the all-solid-state battery of the present invention will be described in detail.

[0039] The method for evaluating pressure applied to an all-solid-state battery of the present invention includes: (1) a step of preparing a test specimen by positioning a pressure-sensitive member on at least one of the upper surface and the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; (2) a step of applying pressure to the test specimen in the thickness direction of the all-solid-state battery; (3) a step of acquiring image information of the pressure-sensitive member after completion of the pressure application in step (2); and (4) a step of determining the pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member.

[0040] First, (Step (1)) In the method for evaluating pressure of an all-solid-state battery according to the present invention, a test specimen is prepared by placing a pressure-sensitive member on at least one of the upper surface and the lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0041] FIG. 1 is a diagram showing a schematic view of a test object (100a) that is the subject of a method for evaluating a battery under pressure according to an embodiment of the present invention.

[0042] Referring to FIG. 1, a test object (100a) according to one embodiment of the present invention includes an electrode assembly (20) of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode, and a pressure-sensitive member (10), and the pressure-sensitive member is located on the upper or lower surface of the electrode assembly. In one embodiment of the present invention, the test subject has a configuration in which the all-solid-state battery and the pressure-sensitive member are housed in an exterior material (50) such as a pouch.

[0043] FIG. 4 is an image showing the external appearance of a subject in which such an all-solid-state battery and a pressure-sensitive member are housed in a pouch and sealed.

[0044] In one embodiment of the present invention, the subject has a pressure-sensitive member located only on the upper surface of the electrode assembly, a pressure-sensitive member located only on the lower surface of the electrode assembly, or a pressure-sensitive member located on both the upper and lower surfaces of the electrode assembly.

[0045] Furthermore, a test subject in the method for evaluating a solid-state battery under pressure according to an embodiment of the present invention includes a plurality of electrode assemblies and a plurality of pressure-sensitive members. When the test subject includes a plurality of electrode assemblies and a plurality of pressure-sensitive members as described above, the test subject may include a plurality of pressure-sensitive members alternately positioned between individual electrode assemblies constituting the plurality of electrode assemblies.

[0046] FIG. 2 is a diagram showing a schematic view of a test object (100b) that is the subject of a battery pressurization evaluation method according to another embodiment of the present invention.

[0047] Referring to FIG. 2, the specimen (100b) according to one embodiment of the present invention further comprises a buffer layer (30).

[0048] The buffer layer is intended to facilitate application of the analyte to the battery, and any material that can prevent side reactions that may occur between the electrode assemblies can be used for the buffer layer. For example, polymers such as polyurethane (PU) and polytetrafluoroethylene (PTFE), silicon (Si), compounds containing these, or combinations of these can be used, but the buffer layer may be any material commonly used in the art, without being limited thereto.

[0049] The buffer layer may have a thickness that does not affect battery operation, and may be included in a thickness that is generally known in the art.

[0050] In one embodiment of the present invention, the buffer layer is located between the all-solid-state battery and the pressure-sensitive member.

[0051] In one embodiment of the present invention, the buffer layer is located on the lower surface of the all-solid-state battery.

[0052] In one embodiment of the present invention, the buffer layer is located between the lower surface of the all-solid-state battery and the pressure-sensitive member.

[0053] When the buffer layer fills the location, it may be easier to apply to a battery.

[0054] In one embodiment of the present invention, the all-solid-state battery in the subject refers to an electrode assembly of an all-solid-state battery.

[0055] In one embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer.

[0056] The positive electrode current collector is a conductive member that functions as a flow path for electrons that are released from the positive electrode toward an external load in response to a battery reaction or that flow from a power source toward the positive electrode.

[0057] The positive electrode current collector may generally have a thickness of 3 μm to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity and does not induce chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, baked carbon, or aluminum or stainless steel whose surface has been treated with carbon, nickel, titanium, silver, or the like can be used. The current collector may have fine irregularities on its surface to enhance the adhesive strength of the positive electrode active material, and may be in various forms such as a film, sheet, foil, net, porous material, foam, or nonwoven fabric.

[0058] The positive electrode current collector may have a single layer structure made of a single material, or a laminate structure made of an appropriate combination of layers made of these materials. From the viewpoint of reducing the weight of the current collector, it may also include a conductive resin layer made of at least a resin having conductivity.

[0059] The positive electrode active material layer may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0060] The positive electrode active material is not particularly limited as long as it is a lithium composite oxide-based material that allows reversible insertion and desorption of lithium ions, and may include, for example, one or more composite oxides of cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0061] More specifically, the positive electrode active material may be a compound represented by any one of the following chemical formulas: a A 1-b R b D2 (wherein 0.90≦a≦1.8 and 0≦b≦0.5); Li a E 1-b Rb O 2-c D c (wherein 0.90≦a≦1.8, 0≦b≦0.5, and 0≦c≦0.05); LiE 2-b R b O 4-c D c (wherein 0≦b≦0.5 and 0≦c≦0.05); Li a Ni 1-b-c Co b R c D α (wherein 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 (wherein 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 Z2 (wherein 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 (wherein 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 (wherein 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 (wherein 0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05, and 0<α<2); Li a Ni b E c G dO2 (wherein 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 (wherein 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 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a CoG b O2 (wherein 0.90≦a≦1.8 and 0.001≦b≦0.1); Li a MnG b O2 (wherein 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.

[0062] 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; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0063] The conductive material is not particularly limited as long as it is conductive and does not induce chemical changes in the battery. For example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; conductive fibers such as carbon fiber or metal fiber; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives can be used.

[0064] The binder is a component added in consideration of the binding properties of the positive electrode active material, solid electrolyte, and conductive material contained in the positive electrode active material layer. The binder is not limited to any particular type as long as it can be used for forming an electrode in the technical field to which the present invention pertains. For example, the binder may be at least one selected from the group consisting of nitrile-butadiene rubber (NBR), polystyrene, and styrene-butadiene rubber (SBR), and preferably may be a butadiene rubber-based binder such as nitrile-butadiene rubber (NBR) or styrene-butadiene rubber (SBR).

[0065] In one embodiment of the present invention, the solid electrolyte contained 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.

[0066] In one embodiment of the present invention, the solid electrolyte includes a sulfide-based solid electrolyte.

[0067] The sulfide-based solid electrolyte contained in the positive electrode active material layer may be, for example, one represented by the following chemical formula 1.

[0068] [Chemical formula 1] Li aM b S c X d In 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; 0 < a ≤ 6, 0 < b ≤ 6, 0 < c ≤ 6, and 0 < d ≤ 6.

[0069] For example, in Chemical Formula 1, M may be B, Si, Ge, P, or N.

[0070] For example, in Chemical Formula 1, X may be F, Cl, Br, I, or O.

[0071] For example, the sulfide-based solid electrolyte represented by 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.

[0072] The sulfide-based solid electrolyte may have an argyrodite-type crystal structure. By having an argyrodite-type crystal structure, the purity and crystallinity of the sulfide-based solid electrolyte are high, a stable interfacial phase is formed, and while having a high energy density, the potential stability and ionic conductivity can be significantly improved.

[0073] The oxide-based solid electrolyte may be, for example, a compound having a NASICON structure. An example of a compound having a NASICON structure is a compound represented by the general formula Li 1+x Al x Ge 2-x (PO4)3 (0≦x≦2) (LAGP), a compound of the general formula Li 1+x Al x Ti 2-x Examples of oxide-based solid electrolytes include compounds represented by the formula (PO4)3 (0≦x≦2) (LATP). Other examples of oxide-based solid electrolytes include LiLaTiO (for example, Li 0.34 La 0.51 TiO3), LiPON (e.g., Li 2.9 PO 3.3 N 0.46 ), LiLaZrO (e.g., Li7La3Zr2O 12 ) etc.

[0074] The solid electrolyte may have, for example, a particulate shape such as a sphere or oval sphere, or a thin film shape. When the solid electrolyte has a particulate shape, the average particle size may be 0.1 μm to 5 μm.

[0075] The positive electrode active material layer may be prepared according to a method widely known in the art and is not limited to a specific preparation method. For example, the positive electrode active material layer may be prepared by a dry electrode process in which the positive electrode active material, a solid electrolyte, a conductive material, a binder, etc. are mixed to prepare a dough, and then the prepared dough is sheeted; or by a wet process in which the positive electrode active material layer is mixed in a solvent to prepare a slurry positive electrode mixture, and then the slurry is coated on a positive electrode current collector.

[0076] In addition to the above-described positive electrode active material, solid electrolyte, conductive material, and binder, the positive electrode active material layer may further include additives such as a filler, a coating agent, a dispersant, an ion-conductive auxiliary, etc. As the filler, coating agent, dispersant, ion-conductive auxiliary, etc., known materials generally used in electrodes of all-solid-state batteries may be used.

[0077] The thickness of the positive electrode active material layer can be varied depending on the intended configuration of the all-solid-state battery, but is preferably within the range of, for example, 0.1 μm to 1,000 μm, and more preferably 40 μm to 100 μm.

[0078] The solid electrolyte layer is a layer interposed between the positive electrode and the negative electrode, containing a solid electrolyte as a 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. The specific type of the solid electrolyte is the same as that described for the positive electrode active material layer, and therefore a detailed description thereof will be omitted.

[0079] 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. When the solid electrolyte layer has an elastic modulus in such a range, the solid electrolyte contained in the solid electrolyte layer can be more easily pressed and / or sintered.

[0080] The solid electrolyte layer may further include a binder. Examples of the binder included in the solid electrolyte layer include, but are not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Any binder commonly used in the art 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.

[0081] The thickness of the solid electrolyte layer can be varied 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. On the other hand, the lower limit of the thickness of the solid electrolyte layer is not particularly limited, but may be preferably 1 μm or more, 5 μm or more, or 10 μm or more.

[0082] The negative electrode may include a negative electrode active material layer and a negative electrode current collector.

[0083] The negative electrode current collector is a conductive member that functions as a path for electrons that are released from the negative electrode toward a power source or flow from an external load toward the negative electrode depending on the charge / discharge behavior of the battery. The negative electrode current collector is made of, for example, a material that does not react with lithium, i.e., does not form any alloys or compounds. Materials that constitute the negative electrode current collector include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material commonly used as an electrode current collector in the art can be used. The negative electrode current collector can be made of one of the aforementioned metals, or an alloy or coating material of two or more metals. The negative electrode current collector is, for example, in the form of a plate or foil.

[0084] The negative electrode active material layer contains, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0085] The negative electrode active material contained in the negative electrode active material layer may have, for example, a particle form.

[0086] The negative electrode active material included in the negative electrode active material layer may include, for example, at least one selected from a carbon-based negative electrode active material and a metal or semimetal negative electrode active material.

[0087] The carbon-based negative electrode active material is particularly amorphous carbon. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Any material classified as amorphous carbon in the art can be used. Amorphous carbon is carbon that has no or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon.

[0088] The metal or semimetal negative electrode active material may be any metal or semimetal negative electrode active material known in the art that forms an alloy or compound with lithium, including, but not limited to, 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). For example, nickel (Ni) is not a metal negative electrode active material because it does not form an alloy with lithium.

[0089] The negative electrode active material layer may contain one of these negative electrode active materials or a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer may contain only amorphous carbon, or may contain 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). Alternatively, the negative electrode active material layer may contain a mixture of amorphous carbon and 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). The weight ratio of the mixture of amorphous carbon and silver (Ag) or the like is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to these ranges and may be selected depending on the required characteristics of the all-solid-state battery.

[0090] The negative electrode active material layer includes a mixture of first particles of amorphous carbon and second particles of a metal or semi-metal. Examples of the metal or semi-metal include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Other examples of the semi-metal include semiconductors. 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.

[0091] The negative electrode active material layer includes, for example, a binder. Examples of the binder include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. Any binder commonly used in the art can be used. The binder can be a single binder or a combination of multiple different binders.

[0092] The inclusion of a binder in the negative electrode active material layer stabilizes the negative electrode active material layer on the negative electrode current collector. Furthermore, cracking of the negative electrode active material layer is suppressed despite volume changes and / or relative position changes of the negative electrode active material layer during charge / discharge cycles. For example, if the negative electrode active material layer does not contain a binder, the negative electrode active material layer can easily separate from the negative electrode current collector. When the negative electrode active material layer separates from the negative electrode current collector, the negative electrode current collector is exposed and comes into contact with the solid electrolyte layer, increasing the possibility of short circuiting. The negative electrode active material layer is produced, for example, by applying a slurry containing dispersed materials for the negative electrode active material layer to the negative electrode current collector and drying it. The inclusion of a binder in the negative electrode active material layer allows for stable dispersion of the negative electrode active material in the slurry. For example, when applying the slurry to the negative electrode current collector by screen printing, clogging of the screen (e.g., clogging due to aggregates of the negative electrode active material) can be suppressed.

[0093] The negative electrode may further contain additives used in conventional all-solid-state batteries, such as fillers, dispersants, ion conductive materials, and the like.

[0094] The all-solid-state battery can be manufactured by producing the positive electrode, the solid electrolyte layer, and the negative electrode, and then stacking them in this order.

[0095] In one embodiment of the present invention, the electrode assembly stacked in the above order may be housed in a case such as a pouch. Also, two or more electrode assemblies may be stacked to fabricate an all-solid-state battery.

[0096] The pressure-sensitive member refers to a material that can measure whether or not pressure is applied and the magnitude of the pressure. In the present invention, the pressure-sensitive member is not limited to a specific type as long as it can measure whether or not pressure is applied to the subject and evaluate the applied pressure. For example, pressure-sensitive paper can be used as the pressure-sensitive member.

[0097] In one embodiment of the present invention, the pressure-sensitive member is pressure-sensitive paper that changes color when exposed to pressure.

[0098] The pressure-sensitive paper is paper whose color changes depending on the state of pressure applied. If no discoloration or the like appears on the pressure-sensitive paper, it can be determined that no pressure is being applied to that area. Such pressure-sensitive paper has a base material coated with microcapsules and a developer, and develops a certain color when pressure is applied. Furthermore, the color density changes depending on the strength of pressure, and when higher pressure is applied, a darker color appears. Therefore, by visually confirming that the discolored area on the pressure-sensitive paper becomes darker, it can be determined that higher pressure has been applied to that area. In other words, if the pressure-sensitive member is pressure-sensitive paper that changes color when it is pressure-sensitive, the pressure applied to the subject can be measured based on the color development state of the pressure-sensitive paper.

[0099] Commercially available pressure-sensitive paper includes "Prescale" manufactured by Fujifilm Corporation, which can measure the presence or absence of pressure in seven levels depending on the pressure range: minute pressure between 0.05MPa and 0.2MPa, extremely low pressure between 0.2MPa and 0.6MPa, ultra-low pressure between 0.5MPa and 2.5MPa, low pressure between 2.5MPa and 10MPa, medium pressure between 10MPa and 50MPa, high pressure between 50MPa and 130MPa, and ultra-high pressure between 130MPa and 300MPa.

[0100] The presence or absence of discoloration on the pressure-sensitive member can be compared with a reference, such as a standard color sample, and the magnitude of the pressure applied to the subject can be measured through visual evaluation of the density of the discoloration on the pressure-sensitive member.

[0101] In one embodiment of the present invention, the subject includes n pressure-sensitive members (where n is an integer of 1 or more).

[0102] In one embodiment of the present invention, the test subject includes p all-solid-state batteries and q pressure-sensitive members (where p and q are the same or different and each independently represents an integer of 1 or more), and the pressure-sensitive members are included between each of the p all-solid-state batteries, based on the time when the p all-solid-state batteries are sequentially stacked.

[0103] In one embodiment of the present invention, when the subject includes m all-solid-state batteries (where m is an integer of 1 or more) within the subject, the subject includes m+1 or more pressure-sensitive members within the subject, the pressure-sensitive members being on an upper surface and a lower surface of the subject, and the pressure-sensitive members being included between each of the all-solid-state batteries based on the time when the m all-solid-state batteries are sequentially stacked.

[0104] According to an embodiment of the present invention, an evaluation method includes pressure-sensitive members on the upper and lower surfaces of a test object and between all-solid-state batteries, thereby enabling pressure evaluation of a plurality of all-solid-state batteries, thereby improving the efficiency of the evaluation.

[0105] Next, (step (2)) is a step of pressurizing the specimen in the thickness direction of the all-solid-state battery using a pressurizing means.

[0106] The specific configuration of the subject is the same as that explained in the above step (1), and therefore a detailed explanation thereof will be omitted below.

[0107] The pressurizing means may be any means capable of applying pressure to the specimen, and may be, for example, a hydraulic press, specifically, a hand hydraulic press. A representative example of such a pressurizing means is a "jig" that is primarily used to apply pressure or fastening pressure during the operation of an all-solid-state battery. Examples of such a jig include a spring-type jig as shown in FIG. 5 and a washer-type jig as shown in FIG. 6. Furthermore, a warm isostatic press (WIP) method as shown in FIG. 7 may be used as the pressurizing means. Specifically, a specimen manufactured by the WIP method as shown in FIG. 7 may have the appearance shown in FIG. 8.

[0108] In one embodiment of the present invention, the pressing means is performed by a device including a hydraulic press, a jig, or a warm isostatic press. Pressing in the thickness direction means applying pressure in a direction perpendicular to the plane where the all-solid-state battery and the pressure-sensitive member are stacked.

[0109] In one embodiment of the present invention, during pressurization in step (2), the ratio (a / b) of the cross-sectional area (a) of the portion of the pressurizing means that contacts the specimen to the cross-sectional area (b) of the portion of the specimen that contacts the pressurizing means is 8:1 or more. Specifically, the cross-sectional area ratio (a / b) 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 cross-sectional area ratio (a / b) satisfies the above range, pressurization can be uniformly performed over the entire specimen, and the degree of pressurization can be evaluated even with a low pressurization pressure.

[0110] When the cross-sectional area ratio (a / b) is 8:1 or more, uniform pressure can be applied, and when considering the case of evaluating pressure on multiple subjects, the ratio can be significantly greater than 8:1. However, considering the economical aspect for commercial use, the cross-sectional area ratio (a / b) may be 100:1 or less. Specifically, the ratio may 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.

[0111] FIG. 3 is a schematic diagram showing a contact state between the pressure applying means and the subject when pressure is applied according to one embodiment of the present invention.

[0112] Referring to FIG. 3, the cross-sectional area (a) of the portion of the pressure applying means (200) that comes into contact with the specimen (100) means the area of ​​the surface of the pressure applying means (200) that comes into contact with the specimen (100), and the cross-sectional area (b) of the portion of the specimen (100) that comes into contact with the pressure applying means (200) means the area of ​​the surface of the specimen (100) that comes into contact with the pressure applying means (200).

[0113] In one embodiment of the present invention, the pressure applied in step (2) for the evaluation is 0.05 MPa to 10 MPa. Specifically, the pressure 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 is 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.

[0114] According to an embodiment of the present invention, a test subject can be uniformly pressurized even at a moderate pressure, thereby enabling evaluation of the degree of pressure even at a moderate pressure. When the pressure is within the above range, the efficiency and economy of the evaluation can be improved.

[0115] Next, (step (3)) after the pressure application in step (2) is completed, image information of the pressure-sensitive member is acquired, and (step (4)) the pressure distribution of the all-solid-state battery is determined from the acquired image information of the pressure-sensitive member.

[0116] In the test subject, pressure applied perpendicularly to a pressure-sensitive member located on at least one side of the all-solid-state battery is transmitted to a visual image via the pressure-sensitive member, and pressure information about the pressure applied to the pressure-sensitive member and the adjacent all-solid-state battery can be obtained through the visual image. That is, the method for evaluating pressure applied to an all-solid-state battery according to the present invention has the advantage that the process of obtaining information about the strength and uniformity of the pressure applied to the all-solid-state battery through the degree of discoloration, the discolored area, and the distribution of discolored areas in the pressure-sensitive member using the pressure-sensitive member included in the test subject is transmitted as visual image information, making it easy to evaluate pressure, and is convenient in that no separate power source is required for pressure evaluation and the size can be adjusted depending on the size of the test subject.

[0117] In one embodiment of the present invention, the step (3) of acquiring image information of the pressure-sensitive member includes acquiring information on the strength and uniformity of pressure applied to the all-solid-state battery through the degree of discoloration of the pressure-sensitive member, the discolored area, and the distribution of the discolored areas.

[0118] In one embodiment of the present invention, when the object includes n pressure-sensitive members (where n is an integer greater than or equal to 1), the image information of the pressure-sensitive members in step (3) is image information of the pressure-sensitive member located at the (n / 2)th or (n / 2)+1th position when n is an even number, and image information of the pressure-sensitive member located at the (n+1) / 2th position when n is an odd number, based on the n pressure-sensitive members being stacked sequentially. For example, when the object includes eight pressure-sensitive members (an even number), the image information of the pressure-sensitive members may be image information of the pressure-sensitive member located at the fourth or fifth position in the stacking order, which is the (n / 2)th or (n / 2)+1st position, respectively. Alternatively, when the object includes nine pressure-sensitive members (an odd number), the image information of the pressure-sensitive member may be image information of the pressure-sensitive member located at the fifth position in the stacking order, which is the (n+1) / 2th position.

[0119] That is, in the method for evaluating pressure of an all-solid-state battery according to the present invention, when a test object includes a plurality of pressure-sensitive members, image information of the innermost pressure-sensitive member is acquired based on the stacking order of the plurality of pressure-sensitive members. This makes it possible to confirm and evaluate whether the pressure applied through the pressure means is fully transmitted to the inside of the all-solid-state battery. In addition, the image information of the pressure-sensitive member can be used to improve the interfacial characteristics between the cathode active material and the solid electrolyte, which can directly affect the driving and life characteristics of the all-solid-state battery.

[0120] In one embodiment of the present invention, the step of determining the pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member in step (4) includes obtaining color information for each of a plurality of unit inspection areas in the image of the pressure-sensitive member, calculating an average value thereof, and comparing the average value with a standard color sample of the pressure-sensitive member to determine the pressure distribution of the all-solid-state battery.

[0121] Even when pressure is applied through a pressure means, the same pressure may not be applied across the entire area of ​​the pressure-sensitive member. In this case, as a method for evaluating pressure on an all-solid-state battery according to the present invention, the pressure-sensitive member that has undergone the pressure process of step (2) may be divided into a plurality of unit test areas, color image information of each divided area may be obtained, an average value thereof may be calculated, and the calculated average value may be compared with a reference such as a standard color sample, thereby determining the pressure distribution of the all-solid-state battery based on the obtained image information.

[0122] In one embodiment of the present invention, an elastic member is further included on at least one of the upper and lower surfaces of the subject in step (1) before the pressure is applied in step (2).

[0123] The elastic member may be a reinforcing material, a buffer layer, or an elastic layer, and serves to uniformly transmit pressure applied to an electrode assembly including the solid-state battery, improve contact between solid components included in the solid-state battery, and ensure that pressure is applied uniformly to a pressure-sensitive member that can acquire image information through externally applied pressure. The elastic member may be made of any one of polytetrafluoroethylene (PTFE), silicone, organic rubber, polyurethane, polystyrene, polyethylene, polypropylene, ethylene vinyl acetate (EVA), and polyethylene terephthalate (PET), but is not limited to these examples.

[0124] Pressurized evaluation device for all-solid-state batteries The present invention also provides a pressurized evaluation device for an all-solid-state battery.

[0125] In one embodiment of the present invention, the pressure evaluation device for an all-solid-state battery includes an object to be tested, in which a pressure-sensitive member is located 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 located between the positive electrode and the negative electrode, and pressure means for applying pressure to the object to provide image information on the pressure-sensitive member so that pressure distribution can be confirmed.

[0126] The positive electrode, negative electrode, and solid electrolyte layer of the all-solid-state battery included in the test subject, and the pressure-sensitive member are the same as those described in the pressurization evaluation method for an all-solid-state battery, and therefore, detailed description thereof will be omitted.

[0127] In one embodiment of the present invention, the specimen further comprises a buffer layer.

[0128] The buffer layer is intended to facilitate application of the analyte to the battery, and any material that can prevent side reactions that may occur between the electrode assemblies can be used for the buffer layer. For example, polymers such as polyurethane (PU) and polytetrafluoroethylene (PTFE), silicon (Si), compounds containing these, or combinations of these can be used, but the buffer layer may be any material commonly used in the art, without being limited thereto.

[0129] The buffer layer may have a thickness that does not affect battery operation, and may be included in a thickness that is generally known in the art.

[0130] In one embodiment of the present invention, the buffer layer is located between the all-solid-state battery and the pressure-sensitive member.

[0131] In one embodiment of the present invention, the buffer layer is located on the lower surface of the all-solid-state battery.

[0132] In one embodiment of the present invention, the buffer layer is located between the lower surface of the all-solid-state battery and the pressure-sensitive member.

[0133] When the buffer layer fills the location, it may be easier to apply to a battery.

[0134] In one embodiment of the present invention, the all-solid-state battery in the subject refers to an electrode assembly of an all-solid-state battery.

[0135] The pressurizing means for applying pressure to the specimen is not limited to any particular type, as long as it is capable of applying pressure to the specimen. For example, a pressurizing means using a device including a hydraulic press, specifically a hand hydraulic press, can be used. A representative example of such a pressurizing means is a "jig" that is primarily used to apply pressure or fastening pressure during the operation of an all-solid-state battery. Examples of such a jig include a spring-type jig as shown in FIG. 5 and a washer-type jig as shown in FIG. 6. Furthermore, a warm isostatic press (WIP) method, as shown in FIG. 7, can be used as the pressurizing means. Specifically, a specimen manufactured by the pressurizing method using a warm isostatic press as shown in FIG. 7 may be as shown in FIG. 8.

[0136] In one embodiment of the present invention, the pressing is performed by a device including a hydraulic press, a jig, or a warm isostatic press.

[0137] In one embodiment of the present invention, the pressure applied to the test object is applied in a thickness direction of the all-solid-state battery. The pressure in the thickness direction means that the pressure is applied in a direction perpendicular to the plane where the all-solid-state battery and the pressure-sensitive member are stacked.

[0138] In one embodiment of the present invention, when applying pressure to the subject, the ratio (a / b) of the cross-sectional area (a) of the portion of the pressurizing means that contacts the subject to the cross-sectional area (b) of the portion of the subject that contacts the pressurizing means is 8:1 or more. Specifically, the cross-sectional area ratio (a / b) 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 cross-sectional area ratio (a / b) satisfies the above range, pressurization can be uniformly applied to the entire subject, and the degree of pressurization can be evaluated even with a low pressurization pressure.

[0139] When the cross-sectional area ratio (a / b) is 8:1 or more, uniform pressure can be applied, and when considering the case of evaluating pressure on multiple subjects, the ratio can be significantly greater than 8:1. However, considering the economical aspect for commercial use, the cross-sectional area ratio (a / b) may be 100:1 or less. Specifically, the ratio may 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.

[0140] In the test subject, pressure applied perpendicularly to a pressure-sensitive member located on at least one side of the all-solid-state battery is transmitted to a visual image via the pressure-sensitive member, and pressure distribution information can be obtained through the visual image regarding the pressure applied to the pressure-sensitive member and further to the all-solid-state battery located adjacent thereto. That is, the pressure evaluation device for an all-solid-state battery according to the present invention has the advantage that the process of obtaining information regarding the strength and uniformity of the pressure applied to the all-solid-state battery through the degree of discoloration, the discolored area, and the distribution of discolored areas of the pressure-sensitive member using the pressure-sensitive member included in the test subject is transmitted as visual image information, making it easy to evaluate pressure, and is convenient in that it does not require a separate power source for pressure evaluation and can be adjusted in size depending on the size of the test subject.

[0141] In one embodiment of the present invention, the pressure evaluation device acquires information on the strength and uniformity of pressure applied to the all-solid-state battery through the degree of discoloration, the discolored area, and the distribution of discolored areas in the pressure-sensitive member for evaluation.

[0142] In one embodiment of the present invention, the object contains n pressure-sensitive members (where n is an integer greater than or equal to 1). For example, the image information of the pressure-sensitive members may be image information of the pressure-sensitive member located at the n / 2th or (n / 2)+1th position when n is an even number, or image information of the pressure-sensitive member located at the (n+1) / 2th position when n is an odd number, based on the case where n pressure-sensitive members are stacked sequentially. Specifically, when the object contains eight pressure-sensitive members (an even number), the image information of the pressure-sensitive members may be image information of the n / 2th or (n / 2)+1th pressure-sensitive member located at the fourth or fifth position in the stacking order, respectively. Alternatively, when the object contains nine pressure-sensitive members (an odd number), the image information of the pressure-sensitive member may be image information of the (n+1) / 2th pressure-sensitive member located at the fifth position in the stacking order, respectively.

[0143] That is, in the pressure evaluation device for an all-solid-state battery according to the present invention, when a test object includes a plurality of pressure-sensitive members, image information of the innermost pressure-sensitive member is acquired based on the stacking order of the plurality of pressure-sensitive members, thereby making it possible to confirm and evaluate whether the pressure applied through the pressurizing means is fully transmitted to the inside of the all-solid-state battery. In addition, the image information of the pressure-sensitive member can be used to improve the interfacial characteristics between the positive electrode active material and the solid electrolyte, which can directly affect the driving and life characteristics of the all-solid-state battery.

[0144] In one embodiment of the present invention, the test subject includes p all-solid-state batteries and q pressure-sensitive members (where p and q are the same or different and each independently represents an integer of 1 or more), and the pressure-sensitive members are included between each of the p all-solid-state batteries, based on the time when the p all-solid-state batteries are sequentially stacked.

[0145] In one embodiment of the present invention, when the subject includes m all-solid-state batteries (where m is an integer of 1 or more) within the subject, the subject includes m+1 or more pressure-sensitive members within the subject, the pressure-sensitive members being on an upper surface and a lower surface of the subject, and the pressure-sensitive members being included between each of the all-solid-state batteries based on the time when the m all-solid-state batteries are sequentially stacked.

[0146] An evaluation device according to an embodiment of the present invention includes pressure-sensitive members on the upper and lower surfaces of a test object and between all-solid-state batteries, thereby enabling pressure evaluation of a plurality of all-solid-state batteries, thereby improving the efficiency of the evaluation.

[0147] In one embodiment of the present invention, the pressure-sensitive member is pressure-sensitive paper that changes color when exposed to pressure.

[0148] The pressure-sensitive paper is paper whose color changes depending on the state of pressure applied. If no discoloration or the like appears on the pressure-sensitive paper, it can be determined that no pressure is being applied to that area. Such pressure-sensitive paper has a base material coated with microcapsules and a developer, and develops a certain color when pressure is applied. Furthermore, the color density changes depending on the strength of pressure, and when higher pressure is applied, a darker color appears. Therefore, by visually confirming that the discolored area on the pressure-sensitive paper becomes darker, it can be determined that higher pressure has been applied to that area. In other words, if the pressure-sensitive member is pressure-sensitive paper that changes color when it is pressure-sensitive, the pressure applied to the subject can be measured based on the color development state of the pressure-sensitive paper.

[0149] Commercially available pressure-sensitive paper includes "Prescale" manufactured by Fujifilm Corporation, which can measure the presence or absence of pressure in seven levels depending on the pressure range: minute pressure between 0.05MPa and 0.2MPa, extremely low pressure between 0.2MPa and 0.6MPa, ultra-low pressure between 0.5MPa and 2.5MPa, low pressure between 2.5MPa and 10MPa, medium pressure between 10MPa and 50MPa, high pressure between 50MPa and 130MPa, and ultra-high pressure between 130MPa and 300MPa.

[0150] The presence or absence of discoloration on the pressure-sensitive member can be compared with a reference, such as a standard color sample, and the magnitude of the pressure applied to the subject can be measured through visual evaluation of the density of the discoloration on the pressure-sensitive member.

[0151] In one embodiment of the present invention, the subject may further include an elastic member on at least one of the upper and lower surfaces.

[0152] The elastic member may be a reinforcing material, a buffer layer, or an elastic layer, and serves to uniformly transmit pressure applied to an electrode assembly including the solid-state battery, improve contact between solid components included in the solid-state battery, and ensure that pressure is applied uniformly to a pressure-sensitive member that can acquire image information through externally applied pressure. The elastic member may be made of any one of polytetrafluoroethylene (PTFE), silicone, organic rubber, polyurethane, polystyrene, polyethylene, polypropylene, ethylene vinyl acetate (EVA), and polyethylene terephthalate (PET), but is not limited to these examples.

[0153] Specific examples of the present invention will be presented below. However, the examples described below are merely for the purpose of specifically illustrating or explaining the present invention, and the present invention is not limited thereby. Furthermore, the content not described here can be fully inferred by a person skilled in the art, and therefore, a description thereof will be omitted.

[0154] Manufacturing example: Manufacturing of specimens for pressure evaluation of all-solid-state batteries (1) Manufacturing of the positive electrode Based on a total of 100 parts by weight of the positive electrode layer, LiNi with a particle size (D50) of 5 μm was used as the positive electrode active material. 0.8 Co 0.1 Mn 0.178 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 material, and 1.0 part by weight of styrene butadiene rubber (SBR) binder were placed in a xylene solvent, and 2 mm zirconia balls were added and stirred in a Thinky mixer to produce a slurry.

[0155] The produced slurry is applied to one side of a 15 μm thick aluminum current collector, which serves as a positive electrode current collector, and dried in a vacuum oven at 100°C for 8 hours to prepare a positive electrode for an all-solid-state battery.

[0156] (2) Manufacturing of solid electrolyte layer An acrylic binder (SX-A334, Zeon) was dissolved in an isobutyl isobutyrate (IBIB) solvent to prepare a binder solution. The lithium argyrodite solid electrolyte Li6PS5Cl was added to the binder solution and stirred with a Thinky mixer to adjust the viscosity to an appropriate level. After adjusting the viscosity, 2 mm zirconia balls were added, and the mixture was stirred again with the Thinky mixer to produce a slurry. The slurry contained 98.5 wt% solid electrolyte and 1.5 wt% binder. The slurry was applied to a release PET film with a bar coater and dried at room temperature to produce a solid electrolyte layer.

[0157] (3) Manufacturing of all-solid-state battery electrode assemblies The prepared cathode and solid electrolyte layer were cut and used as the anode. A 100 μm thick lithium metal cathode, solid electrolyte layer, and anode current collector were stacked in this order, sealed into a pouch, and hot isostatically pressed (WIP) at 80°C and 500 MPa for 30 minutes to produce an all-solid-state battery electrode assembly. Under pressure, the cathode was approximately 100 μm thick, the anode approximately 100 μm thick, and the solid electrolyte layer approximately 60 μm thick.

[0158] (4) Manufacturing of pressure evaluation specimens A 0.2 mm thick polyurethane (PU) pad was used as the buffer layer, and pressure-sensitive paper (Prescale manufactured by Fujifilm) was used as the pressure-sensitive material. TM A 18mm x 18mm piece of paper (for low pressure) was punched out, and the buffer layer and pressure-sensitive member were placed on the bottom of the electrode assembly in that order to produce one set of "all-solid-state battery electrode assembly-buffer layer-pressure-sensitive paper." Three sets of "all-solid-state battery electrode assembly-buffer layer-pressure-sensitive paper" were prepared, placed in a laminate-type pouch, and vacuum-sealed at -100 kPa to produce a specimen for pressure evaluation. The specimen for pressure evaluation produced as described above is shown in Figure 4.

[0159] Example 1: Pressure evaluation of all-solid-state batteries (1) The specimen for pressure evaluation manufactured in the above manufacturing example was placed in a jig cell, and pressures of 2.5 MPa, 5.0 MPa, and 7.5 MPa were applied to the specimen in the thickness direction using pressure means: 1) a torque wrench to apply pressure to the specimen, and 2) hydraulic pressure to the jig cell, as shown in Figure 9. In method 1, aluminum fixture plates were placed above and below the specimen, and pressure was applied to the bolts and nuts located at the four corners of the fixture plates using a torque wrench. In method 2, hydraulic pressure was directly applied to the fixture plates located above and below the specimen.

[0160] The specimen was placed in a jig cell after 0.2 mm thick polyurethane (PU) pads were placed on the upper and lower surfaces of the specimen as elastic members.

[0161] After pressure application was completed, the test pouch was disassembled and image information was obtained from the color change of the pressure-sensitive paper inside. This was then compared with a standard color sample to determine the pressure distribution applied to the solid-state battery. The results are shown in Figure 9.

[0162] 9, when pressure is applied to the test specimen using "method 1) applying pressure using a torque wrench," the color of the color-developing paper changes only when a relatively high pressure of 5.0 MPa or more is applied, and even when a pressure of 7.5 MPa is applied, the pressure is not uniform. In contrast, when pressure is applied to the test specimen using "method 2) applying pressure by applying hydraulic pressure to a jig cell," pressure is applied to the test specimen even at a relatively low pressure (2.5 MPa), confirming that pressure is applied uniformly in both the area and thickness directions of the test specimen.

[0163] Example 2: Pressure evaluation of all-solid-state batteries (2) The specimen for pressure evaluation manufactured in the above manufacturing example was placed in two jig cells (first jig cell and second jig cell) each containing fixture plates of different areas, and pressure was applied in the thickness direction of the specimen. The fixture plate of the first jig cell was 770% of the specimen area, and the fixture plate of the second jig cell was 1,480% of the specimen area.

[0164] After pressure application was completed, the pouches of each test specimen were disassembled, and image information was obtained based on the color change of the pressure-sensitive paper inside. This information was then compared with a standard color sample to determine the pressure distribution applied to the solid-state battery. The results are shown in Figure 10.

[0165] 10, when pressure is applied to the test object using "1) first jig cell," a relatively high pressure is applied to the pressure-sensitive paper located at the top of the test object, and the applied pressure is not effectively transmitted to the pressure-sensitive paper located at the bottom of the test object. Also, when pressure is applied to the test object using "first jig cell," which is relatively smaller than "2) second jig cell," it is difficult to apply a relatively low pressure of 5 MPa.

[0166] On the other hand, when pressure is applied to the specimen using "2) Second fixture cell," it can be confirmed that a uniform pressure is applied to the specimen in the area and thickness directions at both relatively high and low pressures.

[0167] 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. [Explanation of symbols]

[0168] 10: Pressure-sensitive member 20: Electrode assembly 30: Buffer layer 50: Exterior material 100: Subject 100a: Subject according to one embodiment of the present invention 100b: Subject according to another embodiment of the present invention 200: Pressurizing means

Claims

1. A method for pressurizing and evaluating an all-solid-state battery including a solid electrolyte, (1) preparing a test specimen by positioning a pressure-sensitive member on at least one of an upper surface and a lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; (2) applying pressure to the specimen in the thickness direction of the all-solid-state battery using a pressure means; (3) after the pressure in the step (2) is applied, acquiring image information of the pressure-sensitive member; (4) determining a pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member; A method for pressurizing and evaluating all-solid-state batteries.

2. The step (3) of acquiring image information of the pressure-sensitive member includes: Obtaining information about the strength and uniformity of pressure applied to the all-solid-state battery through the degree of discoloration, the discolored area, and the distribution of discolored areas of the pressure-sensitive member; The method for evaluating an all-solid-state battery under pressure according to claim 1 .

3. The step of determining the pressure distribution of the all-solid-state battery from the acquired image information of the pressure-sensitive member in the step (4) includes: acquiring color information for each of a plurality of unit inspection areas within the image of the pressure-sensitive member and calculating an average value thereof; The average value is compared with a standard color sample of the pressure-sensitive member to determine the pressure distribution of the all-solid-state battery. The method for evaluating an all-solid-state battery under pressure according to claim 1 .

4. The subject includes n pressure-sensitive members (where n is an integer of 1 or more), The method for evaluating an all-solid-state battery under pressure according to claim 1 .

5. The subject includes p all-solid-state batteries and q pressure-sensitive members (where p and q are the same or different and each independently represents an integer of 1 or more); When the p number of all-solid-state batteries are stacked in order, the pressure-sensitive member is included between each of the all-solid-state batteries. The method for evaluating an all-solid-state battery under pressure according to claim 1 .

6. the pressure-sensitive member is pressure-sensitive paper that changes color when exposed to pressure, measuring the pressure applied to the subject based on the color development state of the pressure-sensitive paper; The method for evaluating an all-solid-state battery under pressure according to claim 1 .

7. The pressing means is performed by a device including a hydraulic press, a jig, or a warm isostatic press. The method for evaluating an all-solid-state battery under pressure according to claim 1 .

8. and (2) further comprising an elastic member on at least one of the upper and lower surfaces of the subject in (1) before the pressure is applied thereto. The method for evaluating an all-solid-state battery under pressure according to claim 1 .

9. During the pressurization in step (2), the ratio (a / b) of the cross-sectional area (a) of the portion of the pressurizing means that comes into contact with the specimen to the cross-sectional area (b) of the portion of the specimen that comes into contact with the pressurizing means is 8:1 or more. The method for evaluating an all-solid-state battery under pressure according to claim 1 .

10. a test object having a pressure-sensitive member located on at least one of an upper surface and a lower surface of an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; a pressure means for applying pressure to the subject and providing image information to the pressure-sensitive member so that pressure distribution can be confirmed; A pressurized evaluation device for all-solid-state batteries.

11. The pressure applied to the subject is applied in a thickness direction of the all-solid-state battery. The apparatus for evaluating pressurization of an all-solid-state battery according to claim 10.

12. The subject includes n pressure-sensitive members (where n is an integer of 1 or more), The apparatus for evaluating pressurization of an all-solid-state battery according to claim 10.

13. The pressure-sensitive member is pressure-sensitive paper that changes color when exposed to pressure. The apparatus for evaluating pressurization of an all-solid-state battery according to claim 10.

14. The pressing means is a device including a hydraulic press, a jig, or a warm isostatic press; The apparatus for evaluating pressurization of an all-solid-state battery according to claim 10.

15. The device further includes an elastic member on at least one of the upper and lower surfaces of the subject. The apparatus for evaluating pressurization of an all-solid-state battery according to claim 10.

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