Electrolyte layer structure for solid-state battery and method for producing a solid-state battery having the electrolyte layer structure and vehicle

Abstract

Electrolyte layer structure (20) for a solid-state accumulator, comprising: a first electrolyte layer (21) formed on a substrate (10), the first electrolyte layer (21) comprising a first binder and a first solid electrolyte; and a second electrolyte layer (22) formed on the first electrolyte layer (21), the second electrolyte layer (22) comprising a second binder and a second solid electrolyte, wherein a thickness (t1) of the first electrolyte layer (21) is less than a thickness (t2) of the second electrolyte layer (22), and wherein a content of the first binder of the first electrolyte layer (21) is lower than a content of the second binder of the second electrolyte layer (22).

Description

TECHNICAL FIELD

[0001] The present invention relates to a solid-state battery having an electrolyte layer structure and a method for manufacturing a solid-state battery having the electrolyte layer structure. In particular, the quality of the solid-state battery can be ensured by means of a durable lamination between the electrolyte layer structure and an electrode layer. BACKGROUND

[0002] A solid-state battery has a solid-state electrolyte that replaces a polymer electrolyte to improve chemical stability and avoid problems such as liquid leakage or ignition.

[0003] In a solid-state battery, an electrode layer and an electrolyte layer may have an increased thickness to improve properties of a solid-state electrolyte and to increase energy density.

[0004] In order to increase the thickness of the electrode layer and the electrolyte layer, various methods have been used to manufacture a solid-state battery in which the electrolyte layer and the electrode layer were laminated together.

[0005] For example, a method for manufacturing an all-solid-state storage battery is known from the related art. A substrate, such as a sheet or film, is coated with a solid electrolyte slurry having a predetermined thickness and dried to form an electrolyte layer, and the substrate is disposed on one surface of the electrolyte layer. A positive electrode layer (a layer constituting a positive electrode) or a negative electrode layer (a layer constituting a negative electrode) is laminated onto the other surface of the electrolyte layer and subsequently affixed thereto by pressing. Thereafter, the substrate disposed on one surface of the electrolyte layer is removed, and an electrode layer of opposite polarity can be affixed to one surface of the electrolyte layer by pressing.However, in the method for manufacturing an all-solid-state battery according to the related art, the substrate cannot be smoothly removed from the one surface of the electrolyte layer, and therefore, the quality cannot be ensured, and an interface between the electrolyte layer and the electrode layer may be defective.

[0006] JP 2007-66703 A discloses a lithium-ion secondary battery and a solid electrolyte. JP 2015-69967 A discloses a secondary battery. SHORT DESCRIPTION

[0007] The invention provides an electrolyte layer structure for an all-solid-state battery according to claim 1, a method for manufacturing an all-solid-state battery according to claim 3, a vehicle according to claim 8, and a vehicle according to claim 9. Further embodiments are described in the dependent claims. Accordingly, the different multiple electrolyte layers can enable a substrate to be smoothly removed from the electrolyte layers and an interface between the electrolyte layer structure and an electrode layer to be flat when a lamination technique is used.

[0008] In particular, two or more electrolyte layers may be different with respect to the binder, for example different with respect to the concentration, the amount, and / or the type of binder.

[0009] Furthermore, two or more electrolyte layers differ from each other, for example, due to (1) the type of binder, (2) the concentration and / or amount of binder in each layer, (3) the type of electrolyte, or (4) all of these differences.

[0010] Each of the two or more electrolyte layers can be prepared using (1) a binder solution prepared by mixing the binder and a solvent, and (2) a slurry comprising the solid electrolyte.

[0011] The first electrolyte layer may be formed by mixing a first binder solution comprising the first binder and a first solvent, and a first slurry or mixture comprising the first solid electrolyte. Similarly, the second electrolyte layer may be formed by mixing a second binder solution comprising the second binder and a second solvent, and a second slurry or mixture comprising the second solid electrolyte.

[0012] Attaching the electrode layer to the second electrolyte layer may comprise applying pressure.

[0013] In particular, the difference in thickness between two layers, for example, t1 and t2, can suitably be between 0.5 µm and 30 µm or between 50 µm and 80 µm. The substrate can be suitably coated with the first mixture or slurry by electrospray coating or other methods.

[0014] The first electrolyte layer may be coated with the second mixture or slurry using any suitable coating technique, such as die coating, comma coating, or gravure coating.

[0015] After the process of removing the substrate, an additional electrode layer may be disposed on the first electrolyte layer, wherein the additional electrode layer has an opposite polarity to the electrode layer disposed on the second electrolyte layer. Accordingly, if the electrode layer forms a positive electrode, after removing the substrate from the first electrolyte layer, an additional electrode layer forming a negative electrode may be laminated onto the first electrolyte layer from which the substrate is removed. If the electrode layer forms a negative electrode, after removing the substrate from the electrolyte layer, an additional electrode layer forming a positive electrode may be laminated onto the first electrolyte layer from which the substrate is removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Fig. 1 shows an exemplary method for manufacturing a solid-state battery according to an exemplary embodiment of the present invention. Fig. 2 shows an exemplary process of forming a first electrolyte layer during a method of manufacturing a solid-state battery according to an exemplary embodiment of the present invention. Fig. 3 shows an exemplary process of forming a second electrolyte layer during a method of manufacturing a solid-state battery according to an exemplary embodiment of the present invention. Fig. 4 shows an exemplary process of laminating an electrolyte layer and an electrode layer during a method of manufacturing an all-solid-state battery according to an exemplary embodiment of the present invention. Fig. 5 shows an exemplary process of attaching an electrode layer to a second electrolyte layer of an electrolyte layer structure during a method of manufacturing a solid-state battery according to an exemplary embodiment of the present invention. Fig. 6 shows an exemplary process of removing a substrate from a first electrolyte layer of an electrolyte layer structure during a method of manufacturing a solid-state battery according to an example embodiment of the present invention. Fig. 7 shows an exemplary process of attaching an electrode layer to a first electrolyte layer of an electrolyte layer structure during a method of manufacturing a solid-state battery according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0017] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the reference, dimensions of elements or thicknesses of lines shown in the drawings and referred to to describe the invention may be exaggerated for ease of understanding. Furthermore, the terms used hereinafter must be defined in consideration of the functions of the present invention and may vary depending on the intention of a user or practitioner or conventional practice. Therefore, the terms should be defined based on the entire contents of this specification.

[0018] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a" and "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It is further to be understood that terms such as "comprises" and / or "comprising," when used in this specification, specify the presence of certain features, numbers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features, numbers, steps, acts, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the corresponding listed items.

[0019] Unless otherwise specifically stated or obvious from the context, the term "approximately" as used herein is to be understood as being within a range of tolerance normal in the art, for example, within two standard deviations of the mean. "Approximately" may be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the standard value. Unless otherwise clear from the context, all numerical values ​​provided herein are modified by the term "approximately."

[0020] It is to be understood that the term "vehicle" or "vehicle-related" or other similar terms as used herein include motor vehicles in general, such as passenger automobiles including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including a variety of boats and vessels, aircraft, and the like, and including hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative-fuel vehicles (e.g., powered by fuels derived from resources other than oil). As referred to herein, a hybrid vehicle is a vehicle that has two or more power sources, for example, a gas-powered and electric-powered vehicle.

[0021] Fig. 1 is a flowchart showing a method of manufacturing a solid-state battery according to an exemplary embodiment of the present invention.

[0022] As in Fig. 1, the method for manufacturing a solid-state battery according to an exemplary embodiment of the present invention may include: a first electrolyte layer forming step S1 in which a first electrolyte layer 21 is formed on a substrate 10, a second electrolyte layer forming step S2 in which a second electrolyte layer 22 is formed on the first electrolyte layer 21, a laminating step S3 in which an electrode layer 31 is laminated onto the second electrolyte layer 22, a first attachment process S4 in which the electrode layer 31 is attached to the second electrolyte layer 22, a substrate removing step S5 in which the substrate 10 is removed from the first electrode layer 21, and a second attachment step S6 in which an opposing electrode layer 32 is attached to the first electrolyte layer 21,from which the substrate 10 is removed., Formation of the first electrolyte layer

[0023] As in Fig. 2, in step S1, the substrate 10 may be coated with a first mixture or slurry, which may be dried to form the first electrolyte layer 21 having a thickness t1.

[0024] The first mixture or slurry may comprise a first electrolyte in the form of a solid powder and a first binder solution, and the first binder solution may be suitably prepared by mixing a first binder and a first solvent. Therefore, according to one aspect, the first electrolyte layer 21 may be formed as electrolyte particles 21a bound by the binder 21b, as shown in Fig. 2 shown.

[0025] Thus, the substrate 10 may be coated with the first slurry or mixture which is dried to form the first electrolyte layer 21, and the first electrolyte layer 21 may be in a state in which the substrate 10 is attached to a first surface thereof.

[0026] According to an exemplary embodiment, the first slurry or mixture may be formed as a layer to form the first electrolyte layer and have a predetermined thickness t1. Preferably, the predetermined thickness t1 on the substrate 10 may be in a range from about 0.5 μm to about 30 μm. The coating method may not be particularly limited, and generally used coating methods in the art may be used without limitation. For example, coating with the slurry or mixture may be performed using a doctor blade and subsequently dried at a temperature of about 90 to 130°C under an atmosphere having a moisture content of 1 ppm or less for about 1 to 6 hours to form the first electrode layer 21 on the substrate 10.

[0027] The first solvent may not react with the first electrolyte and may have a suitable viscosity of approximately 1.3 cp at a room temperature of 300 K or more.

[0028] For example, dodecane may be used as the first solvent and poly(ethylene-co-propylene-co-5-methylene-2-norbornene) as the first binder, but the examples are not limited to this.

[0029] According to an exemplary embodiment, the first binder solution can be prepared by mixing an amount of the first binder of approximately 0 to 2 wt% (excluding 0 wt%) based on the total weight of the first solvent into the first solvent and heating the mixture at a temperature of approximately 40°C while stirring the mixture and / or mixing the mixture in an ultrasonic bath. Thus, the first binder solution can have a content of the first binder that is lower than the content of a binder in a conventional electrolyte layer of the conventional solid-state battery. Therefore, the substrate 10 can be easily removed from the electrolyte layer as described below.

[0030] The first binder solution thus prepared, which comprises the first binder in an amount of about 0 to 0.2 wt% (not including 0) based on the total weight of the first binder solution, may be added to and mixed with the first solid electrolyte (for example, a solid powder) to produce the first slurry or mixture having a solid content of about 50 to 70 wt% based on the total weight of the first slurry or mixture.

[0031] The substrate 10 may suitably comprise or be formed from aluminum (Al) or nickel (Ni). Formation of the second electrolyte layer

[0032] As in Fig. 3, the first electrolyte layer 21 may be coated with the second mixture or slurry, which may be dried to form the second electrolyte layer 22 having a predetermined thickness t2 on the other surface of the first electrolyte layer 21 (step S2).

[0033] The second mixture or slurry may comprise an electrolyte in the form of a solid powder and a second binder solution. The second binder solution may be prepared by mixing the second electrolyte and a second solvent. Therefore, the second electrolyte layer 22 may be formed as electrolyte particles 22a arranged or secured by the binder 22b, as shown in Fig. 3 shown.

[0034] Accordingly, the first electrolyte layer 21 may be coated with the second mixture or slurry, which is subsequently dried to form the second electrolyte layer 22, and the first electrolyte layer 21 may be integrally formed on a first surface of the second electrolyte layer 22, or in other words, the second electrolyte layer 22 may be formed on a second surface of the first electrolyte layer 21 that has an opposite polarity to the first surface where it contacts the substrate. A mounting surface to which a first electrode layer 31, as described below, is attached may be formed on the other surface (a second surface) of the second electrolyte layer 22.

[0035] According to an exemplary embodiment, the second electrolyte layer 22 may be formed on another surface (a second surface) of the first electrolyte layer 21 by coating it with the second mixture or slurry. The formed second electrolyte layer 22 may have the predetermined thickness t2 in the range of about 50 to about 80 μm on the substrate 10. The coating methods for forming the second slurry or mixture are not particularly limited. For example, the coating may be suitably performed using a doctor blade, and subsequently, the second slurry or mixture may be dried under an atmosphere having a humidity of 1 ppm or less for about 3 to 8 hours at a temperature of about 90 to 130°C.

[0036] The second solvent may not react with the second electrolyte and may have a viscosity of approximately 1.3 cp at a temperature of 300K or more.

[0037] According to an exemplary embodiment, dodecane can be used as the second solvent and poly(ethylene-co-propylene-co-5-methylene-2-norbornene) can be used as the second binder.

[0038] According to an exemplary embodiment, the second binder solution can be prepared by mixing an amount of approximately 2 to 10 wt% of the second binder based on the total weight of the second solvent with the second solvent, and heating the mixture at a temperature of approximately 40°C while stirring the mixture in an ultrasonic bath. Therefore, the second binder solution can have a second binder content similar to that of the conventional electrolyte layer of the related-art solid-state battery, thereby ensuring a stable and strong connection with the electrode layer 31, as described below.

[0039] The second binder solution having an amount of about 0.5 to 3 wt% of the second binder based on the total weight of the second binder solution may be added to and mixed with the second solid electrolyte (for example, in the form of a solid powder) to produce the second slurry or mixture having the solid content of about 40 to 70 wt% based on the total weight of the second slurry or mixture.

[0040] As can be seen from the foregoing description, the first slurry or mixture in the first electrolyte layer 21 may have a content of the first binder which is lower than the content of the second binder of the second slurry or mixture of the second electrolyte layer 22.

[0041] In addition, the thickness t1 of the first electrolyte layer 21 may be smaller than the thickness t2 of the second electrolyte layer 22. In particular, the thickness t1 of the first electrolyte layer 21 may be appropriately adjusted to facilitate removal (delamination) of the substrate 10, as described below, and to maintain a stable bonding force with respect to the second electrolyte layer 22. Laminating the electrolyte layer and the electrode layer

[0042] Since the second electrolyte layer 22 is integrally formed on the second surface of the first electrolyte layer 21, the first electrolyte layer 21 and the second electrolyte layer 22 may be stacked to form an electrolyte layer structure 20 as shown in Fig. 4. Subsequently, an electrode layer 31 can be laminated onto the second surface of the second electrolyte layer 22 of the electrolyte layer structure 20 (step S3). Here, the electrode layer 31 can be configured as a positive electrode or a negative electrode. First fastening

[0043] The laminated, e.g., bonded, electrolyte layer structure 20 and electrode layer 31 can be fixed to each other by applying a pressure of approximately 5 to 20 MPa (step S4). Removing the substrate

[0044] After the electrode layer 31 is attached to the second electrolyte layer 22 of the electrolyte layer structure 20, the substrate 10 can be removed from the first surface of the first electrolyte layer 21, as shown in Fig. 6 (step S5). Second fastening

[0045] An electrode layer 32 having an opposite polarity to the electrode layer 31 (counter electrode) as described above may be attached to the first surface of the first electrolyte layer 21 from which the substrate 10 has been removed, for example, by applying a pressure of 25 to 40 MPa (step S6). For example, if the electrode layer 31 attached in the first attachment step S5 is a positive electrode, the electrode layer 32 attached in the second attachment step S6 may be a negative electrode, and conversely, if the electrode layer 31 attached in the first attachment step S5 is a negative electrode, the electrode layer 32 attached in the second attachment step S6 may be a positive electrode. Manufacturing the electrode layers

[0046] The electrode layers 31 and 32 can be formed before the electrolyte layer structure 20 is formed.

[0047] According to an exemplary embodiment, the electrode layers 31 and 32 can be formed as a positive electrode complex or a negative electrode complex. A method for forming the electrode layers 31 and 32 will be described in detail below.

[0048] First, an amount of 50 to 85 wt% of active material for the positive electrode or the negative electrode, an amount of 35 to 15 wt% of a solid electrolyte and an amount of 2 to 5 wt% of a conductive material based on the total weight of the mixture can be mixed by means of a tube mixer or by grinding.

[0049] The mixture can then be mixed using a mortar, a bubble-free kneader, a planetary mixer or a vortex mixer.

[0050] A binder solution containing an amount of about 1 to 10 wt% of a third binder, a third solvent, and the like may be added to and mixed with the electrode complex to form a slurry containing an amount of about 40 to 70 wt% solids based on the total weight of the slurry. A substrate may be coated with the slurry to a thickness ranging from about 100 to about 500 µm using a doctor blade, and the positive electrode or negative electrode complex may be dried in a vacuum oven at a temperature of about 90 to 130°C for about 1 to 6 hours to produce a positive electrode layer and a negative electrode layer. The substrate may suitably be formed from Al, C-Al, Ni, and Cu foils.

[0051] The first slurry or mixture of the first electrode layer 21 may have a first binder content lower than a second binder content of the second slurry or mixture of the second electrolyte layer 22 and may therefore have a lower viscosity. Therefore, in the first electrolyte layer forming step S1 described above, the coating with the first slurry or mixture to form the first electrolyte layer 21 may be performed by electrospray coating. When the coating with the first slurry or mixture is performed by electrospray coating, the thickness t1 of the first electrolyte layer 21 can be uniform and durable.

[0052] The second electrolyte layer 22 has a second binder content similar to that of the conventional electrolyte layer of the solid-state battery of the related art. In the second electrolyte layer forming step S2 described above, coating with the second slurry or mixture to form the second electrolyte layer 22 can be performed using any of the coating techniques of die coating, comma coating, or gravure coating.

[0053] Accordingly, in accordance with various exemplary embodiments of the present invention, since the content of the binder of the first slurry or mixture is lower than the content of the binder of the second slurry or mixture, the first electrolyte layer 21 can have lower adhesion than the second electrolyte layer 22, and therefore, the substrate 10 attached to the first surface of the first electrolyte layer 21 can be easily removed, thereby ensuring safety of the lamination process, which is therefore advantageous in terms of quality assurance.

[0054] In addition, since the electrolyte layer structure 20 is formed by sequentially forming the first electrolyte layer 21 and the second electrolyte layer 22, a thickness of the electrolyte layer structure 20 can be uniformly implemented, thereby uniformly distributing a current, thereby significantly improving the performance of the secondary battery.

[0055] In particular, an interface resistance between the electrode layer 31 and the electrolyte layer structure 20 can be minimized by appropriately adjusting the thickness of the first electrolyte layer 21, which has a relatively low binder content.

[0056] As described above, in accordance with various exemplary embodiments of the present invention, by forming the electrolyte layer structure having a structure in which two or more electrolyte layers having different binder contents are laminated, the substrate can be smoothly removed from the electrolyte layer and the interface between the electrolyte layer and electrode layer can be formed flat when a lamination technique is applied. LIST OF REFERENCE SYMBOLS 10 Substrat 20 Electrolyte layer structure 21 first electrolyte layer 22 second electrolyte layer 31, 32 Electrode layer

Claims

[1] Electrolyte layer structure (20) for a solid-state accumulator, comprising: a first electrolyte layer (21) formed on a substrate (10), the first electrolyte layer (21) comprising a first binder and a first solid electrolyte; and a second electrolyte layer (22) formed on the first electrolyte layer (21), the second electrolyte layer (22) comprising a second binder and a second solid electrolyte, wherein a thickness (t1) of the first electrolyte layer (21) is less than a thickness (t2) of the second electrolyte layer (22), and wherein a content of the first binder of the first electrolyte layer (21) is lower than a content of the second binder of the second electrolyte layer (22). [2] The electrolyte layer structure (20) of claim 1, wherein each of the first and second electrolyte layers (21, 22) is prepared using, first, a respective binder solution comprising the respective binder and a respective solvent, and second, a respective slurry or mixture comprising the respective solid electrolyte, wherein the respective solvent does not react with the respective solid electrolyte. [3] A method for producing a solid-state accumulator, the method comprising: Coating a substrate (10) with a first slurry or mixture to form a first electrolyte layer (21) having a thickness (t1); Coating the first electrolyte layer (21) with a second slurry or mixture to form a second electrolyte layer (22) having a thickness (t2); Laminating an electrode layer (31) onto the second electrolyte layer (22); Attaching the electrode layer (31) to the second electrolyte layer (22); and Removing the substrate (10) from the first electrolyte layer (21), wherein a content of a first binder contained in the first slurry or mixture for forming the first electrolyte layer (21) is less than a content of a second binder contained in the second slurry or mixture for forming the second electrolyte layer (22), and wherein the thickness (t1) of the first electrolyte layer (21) is less than the thickness (t2) of the second electrolyte layer (22). [4] The method of claim 3, wherein the substrate (10) is coated with the first slurry or mixture by electrospray coating. [5] Method according to one of claims 3 to 4, wherein the first electrolyte layer (21) is coated with the second slurry or mixture by means of spray printing, dip bath printing or texture roller printing. [6] A method according to any one of claims 3 to 5, wherein the electrode layer (31) forms a positive electrode and, after removing the substrate (10) from the first electrolyte layer (21), an additional electrode layer (32) forming a negative electrode is laminated onto the first electrolyte layer (21) from which the substrate (10) is removed. [7] A method according to any one of claims 3 to 5, wherein the electrode layer (31) forms a negative electrode and, after removing the substrate (10) from the first electrolyte layer (21), an additional electrode layer (32) forming a positive electrode is laminated onto the first electrolyte layer (21) from which the substrate (10) is removed. [8] A vehicle having an electrolyte layer structure (20) according to claim 1 or 2. [9] A vehicle comprising a solid-state accumulator manufactured by a method according to any one of claims 3 to 7.

Images