Method for producing a solid electrode with a solid electrolyte concentration gradient

Abstract

Method for producing an electrode of a solid battery 100 by laminating a cathode current collector 13, a layer of active cathode material 14, a solid electrolyte layer, a layer of active anode material 12 and an anode current collector 11, wherein the layer of active cathode material 14 contains an active cathode material 3, a solid electrolyte and a conductor and the layer of active anode material 12 contains an active anode material 1 and a solid electrolyte, wherein the concentration of the active cathode material 3 closer to the cathode current collector 13 is greater than the concentration of the active cathode material 3 closer to the solid electrolyte layer in the layer of active cathode material 14, the concentration of the active anode material 1 closer to the anode current collector 11 is greater than the concentration of the active anode material 1 closer to the solid electrolyte layer in the layer of active anode material 12, and the concentration level of the layer of active cathode material 14 or the layer of active anode material 12 has a substantially continuous gradient, wherein the active material is introduced into a deposition chamber by injection and applied to the solid electrolyte surface, while the concentration level is controlled by adjusting a flow rate in two or more aerosol containers containing different concentrations of the active material. which includes setting a flow rate in the two or more aerosol containers: Increasing the flow rate from a first generator applied to the solid electrolyte surface, Maintaining the flow rate from the first generator, Increasing the flow rate of a second generator while decreasing the flow rate of the first generator until the flow rate becomes 0, and maintaining the flow rate of the second generator.

Description

TECHNICAL AREA

[0001] The present invention relates to a solid electrode structure with a solid electrolyte concentration gradient and a method for improving the output performance of the solid electrode with improved ion diffusion and for obtaining a high-capacity battery by depositing an anode or cathode electrode, which has such a continuous concentration gradient that it has a higher solid electrolyte content closer to a solid electrolyte interface and a higher active material content similar to a current collector interface, such that the active material content and the solid electrolyte content in the active material layers of the anode and cathode exhibit a concentration gradient, by a single process using an aerosol deposition method. BACKGROUND

[0002] Currently available lithium batteries use electrolytes containing flammable organic solvents, and therefore, the installation of safety devices to suppress temperature increases during short circuits, improvements to the structure to prevent short circuits, and the use of enhanced materials for structural improvement may be necessary. Consequently, it is expected that solid-state batteries, which do not use flammable organic solvents in the battery structure, will offer simplified safety features and improved productivity.

[0003] Electrodes of solid-state lithium batteries typically use a mixture of solid electrolyte materials to enhance the conductivity of lithium ions. For example, in the related prior art, a solid-state lithium secondary battery was provided by sequentially laminating an anode electrode, containing an anode plating layer with an active anode material powder and a solid electrolyte powder, a solid electrolyte layer, and a cathode electrode onto both sides of a plate-shaped anode current collector. This allows for the provision of a solid electrolyte with high adhesion between the anode and cathode electrodes within the battery, thus reducing battery flexion or cracking due to the expansion and contraction of the anode and cathode electrodes during charging and discharging.

[0004] Many solid-state lithium batteries can be among the next generation of batteries, requiring significantly high capacity and output. In one example, a layer of active electrode material can be thickened to achieve the higher capacity. However, the output characteristic can degrade due to the increased resistance caused by the thickening.

[0005] Meanwhile, in the related prior art, a solid-state battery has been developed in which an output characteristic is improved by reducing the diffusion resistance of lithium ions with a composition distribution in which the volume fraction of an active material increases the closer it is to a solid electrolyte interface, relative to a thickness direction. As in Fig.As shown in Figure 1, for example, in an electrode, a layer of active anode material is divided into two sections, and layer 2 of active anode material has a higher solid electrolyte content than layer 1. In this example, the process for manufacturing an electrode with different material ratios can involve several steps to increase the electrode density, such as a rolling process that can be performed after applying each layer with different material ratios, and the rolling process can then be repeated. More precisely, when manufacturing two layers, the layers can be limited to one layer with a high proportion of anode material and one layer with a high proportion of solid electrolyte material.Furthermore, a continuous change in concentration can be applied to the layers, but specific examples or instructions regarding the manufacturing process have not yet been provided.

[0006] The foregoing information disclosed in this Background section is intended only to enhance the understanding of the background of the invention and may therefore also contain information that does not represent the prior art already known to a person skilled in the art in this country.

[0007] JP 2011-124 028 A discloses a manufacturing process for a solid-state lithium-ion secondary battery, wherein a solid electrolyte layer is arranged between a negative electrode material layer and a positive electrode material layer, each consisting of active materials and lithium-ion-conducting solid electrolytes, and a negative electrode current collector and a positive electrode current collector are arranged on the outer surface of each of these electrode material layers.

[0008] US 2012 / 0115028 A1 relates to a solid-state battery designed such that an electrode active material layer of at least one of the positive and negative electrodes has a composition distribution such that a local volume ratio, expressed as the ratio of the volume of an electrode active material contained in a part of the electrode active material layer to the volume of a solid electrolyte material contained in that part of the electrode active material layer, increases in a thickness direction of the electrode active material layer as the part of the electrode active material layer approaches an interface of the solid electrolyte layer towards an interface of a current collector, and a void fraction of the electrode active material layer increases in the thickness direction as the part of the electrode active material layer approaches the interface of the solid electrolyte layer towards the interface of the current collector.

[0009] JP H11-283 664 A describes a solid-state battery consisting essentially of a pair of positive and negative electrodes with a solid electrolyte arranged between them and at least one intermediate layer arranged between the solid electrode and at least one of the electrodes.

[0010] JP 2009-280 874 A provides a method for producing a film-like body wherein the ratio (weight ratio) of a substance originating from a first particle and a substance originating from a second particle in the film is suitably controlled during the formation of the film by an aerosol deposition process using the first particle and the second particle. SUMMARY

[0011] The present invention provides technical solutions to the technical difficulties described above in the prior art. Accordingly, the present invention provides a method for producing an electrode with a structure that improves the output characteristics of a solid-state battery. In particular, the method may include an aerosol deposition process.

[0012] In one respect, the present invention provides a method for manufacturing an electrode of a solid-state battery. The solid-state battery is manufactured by laminating the following: a cathode current collector, a layer of active cathode material, a solid electrolyte layer, a layer of active anode material, and an anode current collector. The active cathode material layer contains an active cathode material, a solid electrolyte, and a conductor, and the active anode material layer contains an active anode material and a solid electrolyte. In particular, in the active cathode material layer, the concentration of the active cathode material is higher closer to the cathode current collector than the concentration of the active cathode material closer to the solid electrolyte layer.Furthermore, in the active anode material layer, the concentration of the active anode material is higher closer to the anode current collector than the concentration of the active anode material closer to the solid electrolyte layer. As such, the concentration level of the active anode and cathode materials exists in a continuous gradient.

[0013] According to the invention, the active material is introduced into a deposition chamber by injection and applied to the solid electrolyte surface, while the concentration level is controlled by adjusting a flow rate in two or more aerosol containers containing different concentrations of the active material, wherein adjusting a flow rate in the two or more aerosol containers comprises: increasing a flow rate from a first generator applied to the solid electrolyte surface, maintaining the flow rate from the first generator, increasing a flow rate from a second generator while decreasing the flow rate of the first generator until the flow rate becomes 0, and maintaining the flow rate of the second generator.Furthermore, a volume ratio of the active material (Vra), which can be represented in the following equation, can be present in a range of about 0.1 to about 0.5 in the solid electrolyte interface and in a range of about 0.5 to about 0.9 in the current collector interface. Volume ratio of active material (Vra) = Volume of active material (Volume of active material + Volume of solid electrolyte) BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The foregoing and further features of the present invention are described in detail below with reference to exemplary embodiments thereof, which are illustrated in the accompanying drawings, which are given here only for illustration and are therefore not limiting to the present invention, and wherein: Fig. Figure 1 schematically represents an exemplary, completely solid electrode of the related prior art, Fig. 2 schematically illustrates an exemplary plurality of aerosols for the production of a consistently solid electrode with a concentration gradient according to an exemplary embodiment of the present invention, Fig. Figure 3 schematically shows an exemplary solid battery electrode with a concentration gradient according to an exemplary embodiment of the present invention, Fig. 4 is an exemplary diagram showing a concentration gradient of an exemplary electrode according to an exemplary embodiment of the present invention, Fig. 5 shows an exemplary aerosol device according to an exemplary embodiment of the present invention and Fig. 6 to Fig. Nine exemplary diagrams are shown, illustrating concentration gradients of electrodes in examples and comparative examples of the present invention.

[0015] The in Fig. The reference figures shown in point 1 include a reference to the following elements, as further explained below: 100 continuous solid battery 1 Anode material 2 Solid electrolyte material 3 Cathode material 11, 13 current collectors 12 layers of active anode material 14 layers of active cathode material 20 anode 30 Cathode 40 Solid electrolyte 12a Layer of active material with high anode material content 12b Layer of active material with a high proportion of solid electrolyte material

[0016] It should be self-evident that the accompanying drawings are not necessarily to scale and represent a slightly simplified depiction of various exemplary features illustrating the basic principles of the invention. The specific design features of the present invention, as disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, are partly determined by the intended application and environment of use. In the figures, the reference numerals refer to the same or equivalent parts of the present invention in all figures of the drawing. DETAILED DESCRIPTION

[0017] The terminology used herein serves only to describe certain embodiments and is not intended to limit the invention. As used herein, the singular forms "a," "an," etc., and "the," etc., are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the terms "comprises" and / or "comprehensive," when used in this description, indicate the presence of the aforementioned features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the related items listed.

[0018] Unless explicitly stated or evident from the context, the term "approximately" should be understood as within a range of normal tolerance in the prior art, for example, within 2 standard deviations from 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 stated value. Unless otherwise indicated by the context, all numerical values ​​provided herein are modified by the term "approximately".

[0019] The following section refers in detail to various exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the invention is described in connection with exemplary embodiments, it should be clear that the present description is not intended to limit the invention to these exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the accompanying claims.

[0020] The present invention provides a new method with which essentially continuous concentration changes can be obtained, such that a higher proportion of electrode material is present in a layer close to a solid electrolyte for a high capacity of an active material.

[0021] In one respect, the present invention provides a method for manufacturing an electrode of a solid-state battery. The solid-state battery is manufactured by laminating a cathode current collector, a layer of active cathode material, a solid electrolyte layer, a layer of active anode material, and an anode current collector. The active cathode material layer contains an active cathode material, a solid electrolyte, and a conductor, and the active anode material layer contains an active anode material and a solid electrolyte. In particular, in the active cathode material layer, the concentration of the active cathode material is higher closer to the cathode current collector than the concentration of the active cathode material closer to the solid electrolyte layer.Furthermore, in the active anode material layer, the concentration of the active anode material is higher closer to the anode current collector than the concentration of the active anode material closer to the solid electrolyte layer. Consequently, the concentration level of the active anode and cathode materials exists in a continuous gradient.

[0022] According to the invention, the active material is introduced by injection, while the concentration level is controlled by adjusting the flow rate in two or more aerosol containers, each containing a different concentration of the respective active material. Furthermore, the volume ratio of the active material (Vra) can be obtained using the following equation. Volume ratio of active material (Vra) = Volume of active material (Volume of active material + Volume of solid electrolyte)

[0023] In certain exemplary embodiments, the volume ratio of the active material can be in the range of approximately 0.1 to approximately 0.5 in the solid electrolyte interface and in the range of approximately 0.5 to approximately 0.9 in the current collector interface. Furthermore, the active material and the solid electrolyte can be introduced into an aerosol container with a first generator in a volume ratio of approximately 1:1 to 3:7, and the active material and the solid electrolyte can be contained in an aerosol container with a second generator in a volume ratio of 7:3.More precisely, the manufacturing process comprises the following: increasing the flow rate of the first generator applied to the solid electrolyte surface, maintaining the flow rate of the first generator, increasing the flow rate of the second generator while decreasing the flow rate of the first generator until the flow rate becomes approximately 0, and maintaining the flow rate of the second generator.

[0024] Alternatively, only the solid electrolyte can be introduced into an aerosol container with a first generator, and the active material and the solid electrolyte can be introduced into an aerosol container with a second generator in a volume ratio of approximately 7:3. More precisely, the manufacturing process can involve: producing the solid electrolyte layer by increasing the flow rate of the first generator, increasing the flow rate of the second generator while decreasing the flow rate of the first generator until it reaches approximately 0, and maintaining the flow rate of the second generator.

[0025] Aerosol deposition processes are typically used to apply a material composition. As in Fig.As shown in Figure 2, to produce an electrode with a concentration gradient according to exemplary embodiments of the present invention, starting material containers, for example aerosol generator 1 and aerosol generator 2, containing two or more compositions of material in different concentrations, can be manufactured. In certain exemplary embodiments, the compositions, which have different compositions, can be mixed and deposited by adjusting the flow rate of each aerosol generated from the respective aerosol generator. Furthermore, the slope of the concentration can be changed, or a concentration gradient can be established, without limitation by adjusting the flow rate.

[0026] As in Fig.As shown in Figure 3, high output power and capacity can be achieved by adjusting the active material / solid electrolyte ratio in the active cathode material layer to create a concentration gradient. Output power can be improved by depositing a greater proportion of solid electrolyte at the solid electrolyte interface than at the current collector interface, thus facilitating ion diffusion. Furthermore, high battery capacity can be achieved by depositing a greater proportion of active material the closer the electrode is to the current collector interface.

[0027] According to certain exemplary embodiments of the present invention, the cathode or anode electrode structure, which has a continuous concentration gradient, can be produced in a single process by aerosol deposition. The methods for producing the present invention may include a method for preparing two aerosol containers with different concentrations and adjusting the flow rate injected from each container such that essentially a continuous concentration gradient is obtained when the coating is applied.

[0028] Furthermore, the volume ratio of the active material (Vra) can be in a range of approximately 0.1 to 0.5 when the active material is located in the solid electrolyte interface, and in a range of approximately 0.5 to 0.9 when the active material is located in the current collector interface. As in Fig.As shown in Figure 4, the concentration changes can have a linear or curved shape without restriction.

[0029] In certain exemplary embodiments, a total of three aerosol generators can be used, and the active anode material layer, the solid electrolyte layer, and the active cathode material layer can be applied in a single process. For example, in one exemplary process, an aerosol generator 1 containing active cathode material / solid electrolyte, an aerosol generator 2 containing solid electrolyte, and an aerosol generator 3 containing active anode material / solid electrolyte can be used to apply the active material layers.

[0030] An aerosol deposition method (ADM) is a process capable of forming a thick, high-density film by propelling a starting material powder with a size below one micrometer onto a substrate at a considerably high velocity through a nozzle, as in Fig.5 is shown. Since the procedure was developed by Dr. Since Akedo from Japan proposed this technology in the late 1990s, there has been significant progress in this area (Properties and Application of Jet Printed Piezoelectric PZT Film for Actuation Purposes, A. Schroth, M. Ichiki, J. Akedo, M. Tanaka, R. Maeda Mechanical Engineering Laboratory, AIST, MITI; Surface and Interface Technology Division Namiki 1-2, Tsukuba 305 Japan; and M. Lebedev, J. Akedo and Y. Akiyama, “Dynamic properties of PZT thick films structured on Si membrane by the aerosol deposition method,” ISAF 2000. Proceedings of the 2000 12th IEEE International Symposium on Applications of Ferroelectrics (IEEE Cat. No. 00CH37076), Honolulu, HI, USA, 2000, pages 455-458, vol. 1).In particular, the process offers the advantages of providing a coating method that allows the production of a thick, high-density film with crystalline structural properties at room temperature; the coating can be applied to various substrates using powders made from starting materials such as metals, ceramics, and polymers; and a stoichiometric ratio of the starting material powders can be maintained, as applied in a thick film (e.g., with a predetermined thickness). Consequently, the process has been used as a new coating technology that offers many advantages compared to existing spraying methods.

[0031] Another aspect is provided, including the design of the device as it is described in Fig.The apparatus is described in section 5. It can include a chamber in which the deposition is carried out, an aerosol generator, and a vacuum pump installed to maintain a vacuum of a few to several tens of Torr when a film is produced. Furthermore, starting material powders can be aerosolized by vacuuming the deposition chamber and the aerosol generator containing the starting material powders using a vacuum pump. Physical vibration can then be applied simultaneously with the release of a transport gas, such as helium and nitrogen, from the aerosol generator. Aerosol, as used here, refers to a state in which powder particles are suspended in the atmosphere, such as cigarette smoke, and aerosolized particles can be accelerated toward the chamber due to the pressure differences created between the main chamber and the aerosol generator.When the aerosol particles are sprayed onto the substrate through the nozzle within the deposition chamber, the spray velocity of the aerosol particles can reach approximately 200 to 400 m / s, and the film formation rate can reach a few µm / min. Therefore, the application area can cover electronic ceramics, structural ceramics, and similar materials. EXAMPLES Example 1 (FIG. 6)

[0032] An active cathode material (LiCoO2), an active anode material (graphite), and a solid electrolyte (Li2S-P2S5 sulfide-based) were prepared. To coat each of the two electrodes with a layer of active material in a concentration gradient, an aerosol generator 1 was filled with a composition of active material and solid electrolyte in a ratio of approximately 30:70 (v / v), and an aerosol generator 2 was filled with a composition of active material and solid electrolyte in a ratio of approximately 70:30 (v / v). When the aerosol coating was applied to the surface of the solid electrolyte electrode, initially only the flux from generator 1 was generated, while the flux from generator 2 was increased and then gradually decreased. Subsequently, the flux from generator 1 was stopped, and only the flux from generator 2 was maintained.This resulted in an electrode in which the composition changed from an initial proportion of approximately 30% v / v of active material at the solid electrolyte interface to approximately 70% v / v at the current collector interface. The volume fraction of the active material in the entire electrode was approximately 50%. Example 2 (FIG. 7)

[0033] An active cathode material (LiCoO2), an active anode material (graphite), and a solid electrolyte (Li2S-P2S5 sulfide-based) were prepared. To coat each of the two electrodes with a layer of active material in a concentration gradient, an aerosol generator 1 was filled with a composition of active material and solid electrolyte in a ratio of approximately 50:50 (v / v), and an aerosol generator 2 was filled with a composition of active material and solid electrolyte in a ratio of approximately 70:30 (v / v). When the aerosol coating was applied to the surface of the solid electrolyte electrode, initially only the flux from generator 1 was generated, while the flux from generator 2 was increased and then gradually decreased. Subsequently, the flux from generator 1 was stopped, and only the flux from generator 2 was maintained.This resulted in an electrode in which the composition changed from an initial proportion of approximately 50% v / v of active material at the solid electrolyte interface to 70% v / v at the current collector interface. The volume fraction of the active material in the entire electrode was approximately 60%. Example 3 (FIG. 8)

[0034] An active cathode material (LiCoO2), an active anode material (graphite), and a solid electrolyte (Li2S-P2S5 sulfide-based) were prepared. To coat the solid electrolyte layer and each of the two electrodes with the active material layer using a concentration gradient, an aerosol generator 1 was filled with a composition of active material and solid electrolyte in a ratio of approximately 0:100 (v / v), and an aerosol generator 2 was filled with a composition of active material and solid electrolyte in a ratio of approximately 70:30 (v / v). The solid electrolyte layer was prepared by generating a flow from aerosol generator 1, thereby producing the solid electrolyte layer. Subsequently, the coating was applied while increasing the flow from generator 2 and decreasing the flow from generator 1.

[0035] Finally, the flow from generator 1 was stopped, and only the flow from generator 2 was maintained, thus producing each of the two electrodes, which possessed the concentration gradient of the active material layer. The volume fraction of the active material in the entire electrode was approximately 55%. Comparative example 1 (FIG. 9)

[0036] To coat each electrode with the layer of active material that had no concentration gradient, an aerosol generator 1 was filled with a composition of active material and solid electrolyte in a ratio of about 70:30 and the aerosol coating was applied to the surface of the solid electrolyte electrode. Comparative example 2 (FIG. 9)

[0037] To coat each electrode with the layer of active material that had no concentration gradient, an aerosol generator 1 was filled with a composition of active material and solid electrolyte in a ratio of about 50:50 (v / v) and then the aerosol coating was applied to the surface of the solid electrolyte electrode.

[0038] The materials used in the comparison examples were an active cathode material (LiCoO2), an active anode material (graphite) and a solid electrolyte (Li2S-P2S5 based on sulfide).

[0039] The results of the battery output comparison are shown in Table 1 below. Table 1 Discharge capacity (mAh / g) plating layer ratio Comparison example 1 Comparison example 2 Example 1 Example 2 Example 3 0,1 55 83 106 80 99 0,5 24 64 85 61 76 2 9 30 58 27 47 5 2 10 36 8 26

[0040] Example 1 shows improved output performance compared to example 2, which has an identical plating layer ratio.

[0041] Example 2 shows a similar output power even with an electrode ratio that is about 20% higher (high capacity) than in comparison example 2.

[0042] Example 3 shows improved performance compared to the comparison examples.

[0043] The present invention relates to a solid electrode structure with a solid electrolyte concentration gradient and provides a method for improving output performance due to improved ion diffusion and obtaining a high-capacity battery by depositing an anode or cathode electrode with a continuous concentration gradient such that it has a higher solid electrolyte content the closer it is to a solid electrolyte interface and a higher active material content near a current collector interface, so that the active material / solid electrolyte ratio of the active material layers of the anode and the cathode exhibits a concentration gradient, by a single method using an aerosol deposition process.

Claims

[1] Method for producing an electrode of a solid battery 100 by laminating a cathode current collector 13, a layer of active cathode material 14, a solid electrolyte layer, a layer of active anode material 12 and an anode current collector 11, wherein the layer of active cathode material 14 contains an active cathode material 3, a solid electrolyte and a conductor and the layer of active anode material 12 contains an active anode material 1 and a solid electrolyte, wherein the concentration of the active cathode material 3 closer to the cathode current collector 13 is greater than the concentration of the active cathode material 3 closer to the solid electrolyte layer in the layer of active cathode material 14, the concentration of the active anode material 1 closer to the anode current collector 11 is greater than the concentration of the active anode material 1 closer to the solid electrolyte layer in the layer of active anode material 12, and the concentration level of the layer of active cathode material 14 or the layer of active anode material 12 has a substantially continuous gradient, wherein the active material is introduced into a deposition chamber by injection and applied to the solid electrolyte surface, while the concentration level is controlled by adjusting a flow rate in two or more aerosol containers containing different concentrations of the active material. which includes setting a flow rate in the two or more aerosol containers: Increasing the flow rate from a first generator applied to the solid electrolyte surface, Maintaining the flow rate from the first generator, Increasing the flow rate of a second generator while decreasing the flow rate of the first generator until the flow rate becomes 0, and maintaining the flow rate of the second generator. [2] Method according to claim 1, wherein a volume ratio of the active material (Vra) is in a range of 0.1 to 0.5 in the solid electrolyte interface and in a range of 0.5 to 0.9 in the current collector interface, wherein the volume ratio of the active material is obtained as follows: Volume ratio of active material (Vra) = Volume of active material (Volume of active material + Volume of solid electrolyte) [3] Method according to claim 1, wherein the active material and the solid electrolyte are contained in a volume ratio of 1:1 to 3:7 in the aerosol container with the first generator and the active material and the solid electrolyte are contained in a volume ratio of 7:3 in the aerosol container with the second generator. [4] Method of claim 1, wherein only the solid electrolyte is introduced into the aerosol container with the first generator and the active material and the solid electrolyte are contained in the aerosol container with the second generator in a volume ratio of 7:3.

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