Positive electrode for all-solid-state battery, manufacturing method thereof, and all-solid-state battery comprising same

Abstract

The present invention relates to a positive electrode for an all-solid-state battery, a manufacturing method thereof, and an all-solid-state battery comprising same. More specifically, by introducing a positive electrode active material layer manufactured by integrating a first positive electrode active material layer and a second positive electrode active material layer having different compositions into a positive electrode for an all-solid-state battery, it is possible to implement a high-loading positive electrode while reducing a concentration gradient of components in the positive electrode, thereby preventing deterioration of battery performance.

Description

Cathode for all-solid-state battery, method for manufacturing same, and all-solid-state battery including same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0099965, filed July 29, 2024, and Korean Patent Application No. 10-2025-0101985, filed July 28, 2025, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a positive electrode for an all-solid-state battery, a method for manufacturing the same, and an all-solid-state battery including the same.

[0005] As interest in energy storage technology grows and its applications expand to include energy storage in mobile phones, tablets, laptops, camcorders, and even electric vehicles (EVs) and hybrid electric vehicles (HEVs), research and development on electrochemical devices are steadily increasing. Electrochemical devices are receiving the most attention in this regard, and within this field, the development of rechargeable secondary batteries is a particular focus. Recently, research and development has been focused on novel electrode and battery designs to improve capacity density and specific energy.

[0006] Recently, a dry type electrode manufacturing method that does not involve the use of solvents has been proposed to reduce deterioration of electrode materials due to solvents used in electrode manufacturing or side reactions due to solvents remaining after electrode manufacturing.

[0007] A dry electrode can be manufactured by mixing electrode materials such as an electrode active material, a conductive material, and a binder in a powder state without using a solvent to manufacture a mixed powder for an electrode, calendering the mixed powder to manufacture a free-standing type dry electrode film, and laminating the mixed powder with a current collector.

[0008] According to the dry process of manufacturing electrodes in a dry manner, it is possible to manufacture electrodes with high loading compared to the wet process.

[0009] Since the dry process is a process for manufacturing electrodes without a solvent, electrodes manufactured by the dry process include electrode active materials, solid electrolytes, conductive materials, and binders as components.

[0010] When increasing the electrode thickness to manufacture a high-loading electrode, a concentration gradient of electrode components may occur within the electrode as the thickness increases. This concentration gradient within the electrode can lead to a reduction in the active area and accumulation of electrochemical stress, which can lead to poor battery performance.

[0011] Therefore, there is a need for the development of a technology to prevent battery performance degradation by alleviating the concentration gradient of electrode components within the high-loading electrode.

[0012] [Prior Art Literature]

[0013] (Patent Document 1) Korean Patent Publication No. 2020-0083439

[0014] The inventors of the present invention have conducted various studies to solve the above problems and have confirmed that by introducing a positive electrode active material layer manufactured by integrating a first positive electrode active material layer and a second positive electrode active material layer having different compositions into a positive electrode for an all-solid-state battery, a high-loading positive electrode can be realized while reducing the concentration gradient of components within the positive electrode, thereby preventing inferiority in battery performance.

[0015] Accordingly, the purpose of the present invention is to provide a high-loading all-solid-state battery positive electrode with a reduced concentration gradient of components within the positive electrode.

[0016] Another object of the present invention is to provide a method for manufacturing a high-loading all-solid-state battery positive electrode having a reduced concentration gradient of components within the positive electrode.

[0017] Another object of the present invention is to provide an all-solid-state battery including a high-loading all-solid-state battery positive electrode having a reduced concentration gradient of components within the positive electrode.

[0018] In order to achieve the above object, the present invention provides a positive electrode for an all-solid-state battery, comprising: a positive electrode current collector; and a positive electrode active material layer formed on one surface of the positive electrode current collector;

[0019] The positive electrode active material layer includes a first positive electrode active material layer in contact with one surface of the positive electrode current collector; and a second positive electrode active material layer formed on one surface of the first positive electrode active material layer;

[0020] The first positive electrode active material layer includes a first positive electrode active material, a first solid electrolyte, a first conductive material, and a first fibrous binder, and the second positive electrode active material layer includes a second positive electrode active material, a second solid electrolyte, a second conductive material, and a second fibrous binder.

[0021] The first positive electrode active material layer and the second positive electrode active material layer are integrated without an interface therebetween,

[0022] The contents of the first solid electrolyte and the second solid electrolyte are different,

[0023] The content of the first conductive agent and the content of the second conductive agent are different,

[0024] A positive electrode for an all-solid-state battery is provided, wherein the first positive electrode active material layer and the second positive electrode active material layer are solvent-free.

[0025] In one embodiment of the present invention, the content of the first solid electrolyte is 10 to 25 wt% based on the total weight of the first positive electrode active material layer,

[0026] A positive electrode for an all-solid-state battery is provided, wherein the content of the second solid electrolyte is 10 to 25 wt% based on the total weight of the second positive electrode active material layer.

[0027] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer is 1:4 to 4:1.

[0028] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the thickness of the positive electrode active material layer is 50 to 500 μm.

[0029] In one embodiment of the present invention, a positive electrode for an all-solid-state battery is provided, wherein the porosity of the first positive electrode active material layer is 8% to 20%, and the porosity of the second positive electrode active material layer is 8% to 20%.

[0030] In one embodiment of the present invention, an all-solid-state battery positive electrode is provided, wherein the first fibrous binder and the second fibrous binder each include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), ethylene-vinyl acetate (EVA), styrene-ethylene-butylene-styrene (SEBS), and copolymers containing the same.

[0031] In one embodiment of the present invention, an all-solid-state battery positive electrode is provided, wherein the first solid electrolyte and the second solid electrolyte each include at least one selected from the group consisting of a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0032] In one embodiment of the present invention, an all-solid-state battery positive electrode is provided, wherein the first conductive material and the second conductive material each include at least one linear conductive material selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers.

[0033] In one embodiment of the present invention, the loading of the positive electrode is 6 mAh / cm 2 A positive electrode for an all-solid-state battery is provided.

[0034]

[0035] The present invention also comprises a step of forming a first positive electrode active material layer by mixing (S1) a first positive electrode active material, a first solid electrolyte, a first conductive material, and a first binder and then forming the mixture into a film form using a first sheeting / calendaring process;

[0036] (S2) A step of forming a second positive electrode active material layer by mixing a second positive electrode active material, a second solid electrolyte, a second conductive agent, and a second binder and then forming the mixture into a film shape through a second sheeting / calendering process;

[0037] (S3) A step of sequentially laminating the first positive electrode active material layer and the second positive electrode active material layer on one side of the positive electrode current collector; and

[0038] (S4) A method for manufacturing a positive electrode for an all-solid-state battery is provided, including a step of sequentially stacking a positive electrode laminate, a solid electrolyte membrane, and a negative electrode obtained in the step (S3), and then performing warm isostatic pressing (WIP) to integrate a first positive electrode active material layer and a second positive electrode active material layer included in the positive electrode laminate.

[0039] In one embodiment of the present invention, a method for manufacturing a positive electrode for an all-solid-state battery is provided, wherein the first calendaring process and the second calendaring process are each performed at a temperature of 20°C to 200°C for 1 to 50 loops.

[0040] In one embodiment of the present invention, a method for manufacturing a positive electrode for an all-solid-state battery is provided, wherein the isostatic pressing is performed at a temperature of 50°C to 90°C and a pressure of 300 MPa to 700 MPa.

[0041]

[0042] The present invention also provides an all-solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte membrane interposed therebetween.

[0043] According to the positive electrode for an all-solid-state battery according to the present invention, since the positive electrode is formed by integrating a first positive electrode active material layer and a second positive electrode active material layer having different internal compositions, the possibility of a concentration gradient of components occurring within the positive electrode active material layer is reduced, and thus, there is an effect of preventing deterioration of the electrode due to the occurrence of a concentration gradient.

[0044] Figure 1 is a schematic diagram showing a longitudinal cross-section of a positive electrode for an all-solid-state battery according to one embodiment of the present invention.

[0045] Figure 2 is a schematic diagram showing a positive electrode for an all-solid-state battery and a method for manufacturing an all-solid-state battery according to Example 1 of the present invention.

[0046] Figure 3 is a schematic diagram showing a positive electrode for an all-solid-state battery and a method for manufacturing an all-solid-state battery according to Comparative Example 1 of the present invention.

[0047] FIG. 4a and FIG. 4b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result for a cross-section of an all-solid-state battery manufactured in Example 1.

[0048] FIG. 5a and FIG. 5b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result of a cross-section of a bonding surface of a first positive electrode active material layer and a second positive electrode active material layer included in a positive electrode of an all-solid-state battery manufactured in Example 1 of the present invention.

[0049] Figures 6a and 6b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result for a cross-section of an all-solid-state battery manufactured in Comparative Example 1.

[0050] Figure 7 is a graph showing the initial charge / discharge characteristics of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.

[0051] Figures 8a and 8b are graphs showing the initial charge / discharge characteristics and output characteristics of the all-solid-state batteries manufactured in Examples 1 and 3, respectively.

[0052] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0053] The terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0054] The term “concentration gradient” as used herein means a form in which the concentration of a component within the anode gradually increases or decreases.

[0055] The term “integrated” as used herein means that a first positive electrode active material layer and a second positive electrode active material layer having different internal compositions form a single positive electrode active material layer. Specifically, it means a form in which the interfaces of the first positive electrode active material layer and the second positive electrode active material layer are in contact with each other without a physical space or distance therebetween. Although the internal compositions of the first positive electrode active material layer and the second positive electrode active material layer are different, the integrated first positive electrode active material layer and the second positive electrode active material layer have no physical space or distance therebetween, and thus electrons and ions can be transferred to each other.

[0056]

[0057] Cathode for all-solid-state batteries

[0058] The present invention relates to a positive electrode for an all-solid-state battery.

[0059] The positive electrode for an all-solid-state battery according to the present invention is an all-solid-state battery positive electrode including a positive electrode current collector; and a positive electrode active material layer formed on one surface of the positive electrode current collector;

[0060] The positive electrode active material layer includes a first positive electrode active material layer in contact with one surface of the positive electrode current collector; and a second positive electrode active material layer formed on one surface of the first positive electrode active material layer;

[0061] The first positive electrode active material layer includes a first positive electrode active material, a first solid electrolyte, a first conductive material, and a first fibrous binder, and the second positive electrode active material layer includes a second positive electrode active material, a second solid electrolyte, a second conductive material, and a second fibrous binder.

[0062] The first positive electrode active material layer and the second positive electrode active material layer are integrated without an interface therebetween,

[0063] The first solid electrolyte and the second solid electrolyte are different,

[0064] The contents of the first and second conductive agents are different,

[0065] The content of the first solid electrolyte and the content of the first conductive material are weights based on the total weight of the first positive electrode active material layer, and the content of the second solid electrolyte and the content of the second conductive material are weights based on the total weight of the second positive electrode active material layer.

[0066] The first positive electrode active material layer and the second positive electrode active material layer may be solvent-free.

[0067]

[0068] Figure 1 is a schematic diagram showing a longitudinal cross-section of a positive electrode for an all-solid-state battery according to one embodiment of the present invention.

[0069] Referring to FIG. 1, a positive electrode (100) for an all-solid-state battery includes a positive electrode current collector (110); and a positive electrode active material layer (20) formed on one surface of the positive electrode current collector (110), wherein the positive electrode active material layer (20) includes a first positive electrode active material layer (121) in contact with one surface of the positive electrode current collector (110); and a second positive electrode active material layer (122) formed on one surface of the first positive electrode active material layer (121).

[0070]

[0071] In one embodiment of the present invention, the positive electrode active material layer is formed by integrating the first positive electrode active material layer and the second positive electrode active material layer, and there is no physical space or distance between the positive electrode active material layer and the second positive electrode active material layer. The first positive electrode active material layer and the second positive electrode active material layer differ in the content of the solid electrolyte, the content of the conductive material, and the thickness.

[0072] Specifically, since the first positive electrode active material layer is in contact with the positive electrode current collector, its conductivity may be better than that of the second positive electrode active material layer. However, since the distance from the solid electrolyte membrane is far, its ionic conductivity may be relatively poor compared to that of the second positive electrode active material layer. Accordingly, the first positive electrode active material layer may include a larger amount of solid electrolyte than the second positive electrode active material layer to supplement the ionic conductivity.

[0073] In addition, since the second positive electrode active material layer is in contact with the solid electrolyte membrane, the ionic conductivity may be better than that of the first positive electrode active material layer, but the distance from the positive electrode current collector is far, so the conductivity may be relatively poor compared to that of the first positive electrode active material layer. Accordingly, the second positive electrode active material layer may include a larger amount of conductive material than the first positive electrode active material layer to supplement the conductivity.

[0074]

[0075] In one embodiment of the present invention, the first solid electrolyte and the second solid electrolyte may each include at least one selected from the group consisting of a sulfide-based solid electrolyte and an oxide-based solid electrolyte. The first solid electrolyte and the second solid electrolyte may be the same or different.

[0076] The above sulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0077] <Chemical Formula 1>

[0078] L a1 M b1 P c1 S d1 A e1

[0079] In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, and a1 to e1 represent the composition ratio of each element, with a1: b1:c1:d1:e1 being 1 to 12:0 to 1:1:2 to 12:0 to 5.

[0080] For example, the above sulfide-based solid electrolyte may be an LPS-type sulfide containing sulfur and phosphorus, an LPSCl-type sulfide, or Li 4-x Ge 1-x P x S4 (x is 0.1 to 2, specifically x is 3 / 4, 2 / 3), Li 10±1 MP2X 12 (M=Ge, Si, Sn, Al, X=S, Se), Li 3.833 Sn 0.833 As 0.166 S4, Li4SnS4, Li 3.25 Ge 0.25 P 0.75 S4, Li2S-P2S5, B2S3-Li2S, xLi2S-(100-x)P2S5 (x is 70 to 80), Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-LiCl-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-SiS2-Li3N, Li2S-SiS2-LiI, Li2S-B2S3-LiI, etc., but It is not necessarily limited. For example, the LPSCl type sulfide may be Li6PS5Cl.

[0081] In addition, the oxide-based solid electrolyte may be represented by the following chemical formula 2:

[0082] <Chemical Formula 2>

[0083] Li1+x+y Al x Ti 2-x Si y P 3-y O 12

[0084] (In the above chemical formula 2, x is 0≤ x ≤2, and y is 0≤ y ≤3.)

[0085] For example, the above oxide-based solid electrolyte is Li 3x La 2 / 3-x LLT system with perovskite structure such as TiO3, Li 14 LISICON, Li such as Zn(GeO4)4 1.3 Al 0.3 Ti 1.7 LATP series such as (PO4)3, (Li 1+x Ge 2-x Al x LAGP systems such as (PO4)3) and phosphate systems such as LiPON can be appropriately selected and used, but are not necessarily limited thereto.

[0086] Additionally, the solid electrolyte may be in an amorphous or crystalline state. Additionally, it may be in a mixed amorphous and crystalline state.

[0087]

[0088] In one embodiment of the present invention, the content of the first solid electrolyte may be 10 to 25 wt% based on the total weight of the first positive electrode active material layer, and the content of the second solid electrolyte may be 10 to 25 wt% based on the total weight of the second positive electrode active material layer. Specifically, the content of the first solid electrolyte may be 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, 17 wt% or more, or 18 wt% or more, and may be 25 wt% or less, 24 wt% or less, 23 wt% or less, 22 wt% or less, 21 wt% or less, 20 wt% or less, or 19 wt% or less, based on the total weight of the first positive electrode active material layer. In addition, the content of the second solid electrolyte may be 10 wt% or more, 11 wt% or more, 12 wt% or more, 13 wt% or more, 14 wt% or more, 15 wt% or more, 16 wt% or more, 17 wt% or more, or 18 wt% or more, and may be 25 wt% or less, 24 wt% or less, 23 wt% or less, 22 wt% or less, 21 wt% or less, 20 wt% or less, or 19 wt% or less, based on the total weight of the second positive electrode active material layer.

[0089] If the content of the first solid electrolyte is less than 10 wt%, the effect of improving the ionic conductivity of the first positive electrode active material layer may be minimal, and if it exceeds 25 wt%, the content of the first positive electrode active material, the first conductive material, or the second fibrous binder inside the first positive electrode active material layer may relatively decrease, thereby lowering the capacity, conductivity, or bonding strength of the battery.

[0090] In addition, if the content of the second solid electrolyte is less than 10 wt%, the ionic conductivity of the second positive electrode active material layer may decrease, and if it exceeds 25 wt%, the content of the second positive electrode active material, the second conductive material, or the second fibrous binder inside the second positive electrode active material layer may relatively decrease, thereby lowering the capacity, conductivity, or bonding strength of the battery.

[0091] In one specific example, the content of the first solid electrolyte may be greater than the content of the second solid electrolyte.

[0092]

[0093] In one embodiment of the present invention, the first positive electrode active material layer and the second positive electrode active material layer may be solvent-free.

[0094] Both the first positive electrode active material layer and the second positive electrode active material layer may be manufactured by a dry process that does not use a solvent. Specifically, the first positive electrode active material layer may be manufactured by applying a mixture of a first positive electrode active material, a first conductive material, and a first binder as raw materials to a first calendaring process. The second positive electrode active material layer may also be manufactured by applying a mixture of a second positive electrode active material, a second conductive material, and a second binder to a second calendaring process. Therefore, the manufactured first positive electrode active material layer and the manufactured second positive electrode active material layer do not contain any solvent at all.

[0095] In addition, the first binder and the second binder, which are raw materials used to manufacture the first positive electrode active material layer and the second positive electrode active material layer, are converted into fibers through a calendaring process as described below, thereby becoming the first fibrous binder and the second fibrous binder. Since these first fibrous binders and second fibrous binders are entangled to form a net shape, the strength of the positive electrode can be improved.

[0096] In addition, since a separate solvent is not used, the phenomenon of the crystal structure of the solid electrolyte being destroyed by the solvent and the ionic conductivity being reduced can be prevented.

[0097]

[0098] In one embodiment of the present invention, the content of the first conductive material may be 0.01 to 3 wt% based on the total weight of the first positive electrode active material layer, and the content of the second conductive material may be 0.01 to 3 wt% based on the total weight of the second positive electrode active material layer. Specifically, the content of the first conductive material or the second conductive material may be 0.01 wt% or more, 0.05 wt% or more, 0.1 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1 wt% or more, 1.1 wt% or more, 1.2 wt% or more, 1.3 wt% or more, 1.4 wt% or more, or 1.5 wt% or more, and may be 3 wt% or less, 2.9 wt% or less, 2.8 wt% or less, 2.7 wt% or less, 2.6 wt% or less, 2.5 wt% or less, 2.4 wt% or less, 2.3 wt% or less, 2.2 wt% or less, It may be 2.1 wt% or less, 2 wt% or less, 1.9 wt% or less, 1.8 wt% or less, 1.7 wt% or less, or 1.6 wt% or less.

[0099] If the content of the first conductive material is less than 0.01 wt%, the conductivity within the first positive electrode active material layer may be reduced, and if it exceeds 3 wt%, the content of the first positive electrode active material, the first solid electrolyte, or the first fibrous binder within the first positive electrode active material layer may be relatively reduced, thereby reducing the capacity, ionic conductivity, or binding force of the battery.

[0100] In addition, if the content of the second conductive agent is less than 0.01 wt%, the effect of improving the conductivity of the second positive electrode active material layer may be minimal, and if it exceeds 3 wt%, the content of the second positive electrode active material, the second solid electrolyte, or the second fibrous binder inside the second positive electrode active material layer may relatively decrease, thereby lowering the capacity, ionic conductivity, or binding force of the battery.

[0101]

[0102] In addition, the first and second conductive materials are not particularly limited as long as they prevent side reactions in the internal environment of the all-solid-state battery and have excellent electrical conductivity without causing chemical changes in the battery. For example, the first and second conductive materials may each include at least one linear conductive material selected from the group consisting of carbon nanotubes and carbon nanofibers.

[0103]

[0104] In one embodiment of the present invention, the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer may be 1:4 to 4:1. The thickness ratio may also be expressed as 1:4 (1 / 4) or more and 4:1 (4 / 1) or less. Specifically, the thickness ratio may be 1:4 or more, 2:4 or more, or 3:4 or more, and may be 4:1 or less, 3:1 or less, or 2:1 or less. If the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer is less than 1:4, the thickness of the first positive electrode active material layer may become relatively excessively small, thereby lowering the conductivity, and if it exceeds 4:1, the thickness of the second positive electrode active material layer may become relatively excessively small, thereby lowering the ionic conductivity. The thickness ratio may be appropriately adjusted within the above range in consideration of the conductivity and ionic conductivity of the first positive electrode active material layer and the second positive electrode active material layer.

[0105]

[0106] In one embodiment of the present invention, the thickness of the positive electrode active material layer may be 50 ㎛ to 500 ㎛.

[0107] If the thickness of the positive electrode active material layer is less than 50 ㎛, the loading of the positive electrode may decrease, and if it exceeds 500 ㎛, it may act as resistance within the battery. Specifically, the thickness of the positive electrode active material layer may be 50 ㎛ or more, 60 ㎛ or more, 70 ㎛ or more, 80 ㎛ or more, 90 ㎛ or more, 100 ㎛ or more, 110 ㎛ or more, 120 ㎛ or more, 130 ㎛ or more, 140 ㎛ or more, 150 ㎛ or more, 160 ㎛ or more, 170 ㎛ or more, 180 ㎛ or more, or 190 ㎛ or more, or 500 ㎛ or less, 490 ㎛ or less, 480 ㎛ or less, 470 ㎛ or less, 460 ㎛ or less, 450 ㎛ or less, 440 ㎛ or less, 430 ㎛ or less, 420 ㎛ or less, 410 ㎛ or less, 400 ㎛ or less, 390 ㎛ or less, 380 ㎛ or less, 370 ㎛ or less, 360 It may be ㎛ or less, 350 ㎛ or less, 340 ㎛ or less, 330 ㎛ or less, 320 ㎛ or less, 310 ㎛ or less, 300 ㎛ or less, 290 ㎛ or less, 280 ㎛ or less, 270 ㎛ or less, 260 ㎛ or less, 250 ㎛ or less, 240 ㎛ or less, 230 ㎛ or less, 220 ㎛ or less, or 210 ㎛ or less.

[0108]

[0109] In one embodiment of the present invention, the porosity of the first positive electrode active material layer may be 8% to 20%, and the porosity of the second positive electrode active material layer may be 8% to 20%. Both the first positive electrode active material layer and the second positive electrode active material layer are manufactured by a dry process that does not use a solvent, and thus may have relatively low porosity. Specifically, the porosity of the first positive electrode active material layer and the second positive electrode active material layer may be 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more, or 14% or more, and 20% or less, 19% or less, 18% or less, 17% or less, or 16% or less, respectively.

[0110]

[0111] If the porosity of the first positive electrode active material layer or the second positive electrode active material layer is less than 8%, the durability of the positive electrode may be reduced, and if it is more than 20%, the ionic conductivity may be reduced.

[0112]

[0113] In one embodiment of the present invention, the first fibrous binder and the second fibrous binder may each include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), ethylene-vinyl acetate (EVA), styrene-ethylene-butylene-styrene (SEBS), and copolymers containing the same. The first fibrous binder and the second fibrous binder may be the same or different.

[0114] The first positive electrode active material layer and the second positive electrode active material layer may both be manufactured by a dry process. The dry process is a calendaring process performed without using a solvent, and through the calendaring process, a first fibrous binder and a second fibrous binder can be obtained in a fibrous form. The first fibrous binder and the second fibrous binder are each connected to form a network shape, so that the strength of the first positive electrode active material layer and the second positive electrode active material layer can be enhanced.

[0115] In addition, the content of the first fibrous binder may be 0.2 to 3 wt% based on the total weight of the first positive electrode active material layer, and the content of the second fibrous binder may be 0.2 to 3 wt% based on the total weight of the second positive electrode active material layer. Specifically, the content of the first fibrous binder or the second fibrous binder may be 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, 0.5 wt% or more, 0.6 wt% or more, 0.7 wt% or more, 0.8 wt% or more, 0.9 wt% or more, 1 wt% or more, 1.1 wt% or more, 1.2 wt% or more, 0.3 wt% or more, 1.4 wt% or more, or 1.5 wt% or less, and may be 3 wt% or less, 2.5 wt% or less, or 2 wt% or less.

[0116] If the content of the first fibrous binder is less than 0.2 wt%, the bonding strength within the first positive electrode active material layer or the bonding strength with the positive electrode current collector may be reduced, and if it exceeds 3 wt%, the content of the first positive electrode active material, the first solid electrolyte, or the first conductive material within the first positive electrode active material layer may be relatively reduced, thereby reducing the capacity, ionic conductivity, or conductivity of the battery.

[0117] In addition, if the content of the second fibrous binder is less than 0.2 wt%, the bonding strength within the second positive electrode active material layer or the bonding strength with the solid electrolyte membrane may be reduced, and if it exceeds 3 wt%, the content of the second positive electrode active material, the second solid electrolyte, or the second conductive material within the second positive electrode active material layer may be relatively reduced, thereby reducing the capacity, ionic conductivity, or conductivity of the battery.

[0118]

[0119] In one embodiment of the present invention, the first positive electrode active material and the second positive electrode active material are not particularly limited as long as they are materials capable of reversibly absorbing and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v ]O2 (wherein M is one or two or more elements selected from the group consisting of Al, Ga, and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, x+y+z+v=1), Li(Li a M b-a-b' M' b' )O 2-c A c (In the above formula, 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, 0≤c≤0.2; M includes at least one selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B, and A is at least one selected from the group consisting of P, F, S and N.) layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-yLithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (wherein, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0120] In addition, the first positive electrode active material and the second positive electrode active material may be included in an amount of 60 to 90 wt% based on the total weight of the first positive electrode active material layer and the second positive electrode active material layer, respectively. Specifically, the content of the first positive electrode active material and the second positive electrode active material may be 60 wt%, 65 wt% or more, or 68 wt% or more, and may be 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, or 72 wt% or less, respectively. If the content of the first positive electrode active material or the second positive electrode active material is less than 60 wt%, battery performance may be deteriorated, and if it is more than 90 wt%, mass transfer resistance may increase.

[0121]

[0122] In one embodiment of the present invention, the positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between the external conductor and the positive electrode active material layer.

[0123] The positive electrode current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, the positive electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or an aluminum-cadmium alloy.

[0124] The above-mentioned positive electrode current collector may have a finely irregular structure on its surface or may employ a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer. Accordingly, the positive electrode current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, or non-woven fabric.

[0125]

[0126] In one embodiment of the present invention, the loading of the positive electrode is 6 mAh / cm 2 It may be more than that. Specifically, the loading of the positive electrode is 6 mAh / cm 2 Above, 7 mAh / cm 2 Above, 8 mAh / cm 2 Above, 9 mAh / cm 2 Above, 10 mAh / cm 2 Above, 11 mAh / cm 2 Above, 12 mAh / cm 2 Above, 13 mAh / cm 2 Above, 14 mAh / cm 2 or more than 15 mAh / cm 2 It can be above. The upper limit of the loading of the above anode is not particularly limited, for example, 30 mAh / cm 2 Below, 25 mAh / cm 2 Less than or equal to 20 mAh / cm 2 It could be as follows:

[0127] As described above, the first positive electrode active material layer and the second positive electrode active material layer have different internal compositions, but are joined and integrated so as not to form an interface, thereby forming a positive electrode active material layer. The concentration gradient of each component within the positive electrode active material layer is minimized, thereby preventing deterioration of the battery.

[0128]

[0129] Method for manufacturing a cathode for an all-solid-state battery

[0130] The present invention also relates to a method for manufacturing a positive electrode for an all-solid-state battery.

[0131] The method for manufacturing a positive electrode for an all-solid-state battery according to the present invention comprises: (S1) a step of forming a first positive electrode active material layer by mixing a first positive electrode active material, a first solid electrolyte, a first conductive material, and a first binder and then forming the mixture into a film shape by a first sheeting / calendaring process; (S2) a step of forming a second positive electrode active material layer by mixing a second positive electrode active material, a second solid electrolyte, a second conductive material, and a second binder and then forming the mixture into a film shape by a second sheeting / calendaring process; (S3) a step of sequentially stacking the first positive electrode active material layer and the second positive electrode active material layer on one surface of a positive electrode current collector; And (S4) a step of sequentially stacking the positive electrode laminate, the solid electrolyte membrane, and the negative electrode obtained in the step (S3), and then performing warm isostatic pressing (WIP) to integrate the first positive electrode active material layer and the second positive electrode active material layer included in the positive electrode laminate.

[0132]

[0133] Hereinafter, the method for manufacturing an all-solid-state battery positive electrode according to the present invention will be described in more detail step by step. Since an all-solid-state battery can be manufactured by the method for manufacturing an all-solid-state battery positive electrode described below, the method for manufacturing an all-solid-state battery positive electrode described below may also be referred to as a method for manufacturing an all-solid-state battery.

[0134]

[0135] In one embodiment of the present invention, in the step (S1), a first positive electrode active material, a first solid electrolyte, a first conductive agent, and a first binder are mixed and then formed into a film form through a first sheeting / calendaring process, thereby forming a first positive electrode active material layer. The types and contents of the first positive electrode active material, the first solid electrolyte, and the first conductive agent are as described above. In addition, the first binder is formed into a fibrous form through the first sheeting / calendaring process. Therefore, the first binder used as a raw material and the first fibrous binder obtained through the first sheeting / calendaring process may have the same constituent materials and contents, with only the shape of the binder being different.

[0136] The above first sheeting / calendaring process may refer to a process of forming the target material of the first sheeting / calendaring process into a film shape using two rollers. At this time, the binder can be fiberized by the sheeting, and the film thickness can be controlled while being formed into a film shape by the calendering.

[0137] In one embodiment of the present invention, the temperature of the first sheeting / calendaring process may be 20°C to 200°C. Specifically, the temperature may be 20°C or higher, 30°C or higher, 40°C or higher, 50°C or higher, 60°C or higher, 70°C or higher, or 80°C or higher, and may be 100°C or lower, 120°C or lower, 140°C or lower, 160°C or lower, 180°C or lower, or 200°C or lower. If the temperature is lower than 20°C, less fiberization of the binder may occur, thereby reducing the strength of the first positive electrode active material layer. If the temperature is higher than 200°C, even if the temperature increases, the strength of the first positive electrode active material layer may no longer increase, or the raw materials may deteriorate.

[0138]

[0139] The first sheeting / calendaring process may be performed for 1 to 50 loops. Specifically, if the number of loops of the first sheeting / calendaring process is less than 1, the binder may not be fiberized, and if it is more than 50, fiberization may progress excessively, so that the strength of the positive electrode no longer increases, or the processability may deteriorate. Specifically, the number of loops of the first calendaring process may be 1 or more, 5 or more, 10 or more, 15 or more, 20 or more, 23 or more, or 25 or more, and may be 50 or less, 45 or less, 40 or less, or 35 or less.

[0140]

[0141] In addition, the orientation of the first sheeting / calendaring process may be performed uniaxially or biaxially. Here, uniaxially means that the sheeting / calendaring direction proceeds in one direction, and biaxially means that the sheeting / calendaring is performed in one direction and then alternately in the horizontal and vertical directions of the first positive electrode active material layer.

[0142] When the above sheeting / calendering process is performed biaxially, fiberization can proceed evenly in multiple directions, further improving the strength of the anode.

[0143]

[0144] In one embodiment of the present invention, in the step (S2), a second positive electrode active material, a second solid electrolyte, a second conductive material, and a second fibrous binder are mixed and then formed into a film form through a second sheeting / calendering process, thereby forming a second positive electrode active material layer. The types and contents of the second positive electrode active material, the second solid electrolyte, the second conductive material, and the second fibrous binder are as described above.

[0145] The description of the above second seating / calendaring process may be the same as the description of the first seating / calendaring process.

[0146]

[0147] In one embodiment of the present invention, in the step (S3), the first positive electrode active material layer and the second positive electrode active material layer are sequentially laminated on one surface of the positive electrode current collector, thereby obtaining a positive electrode laminate.

[0148]

[0149] In one embodiment of the present invention, after sequentially stacking the positive electrode laminate, solid electrolyte membrane, and negative electrode obtained in step (S3) above (S4), warm isostatic pressing (WIP) is performed to integrate the first positive electrode active material layer and the second positive electrode active material layer included in the positive electrode laminate.

[0150] The above WIP process refers to a process that simultaneously applies high temperature and isotropic pressure. When the WIP process is performed on the laminate obtained in step (S3), the bonding surface between the first positive electrode active material layer and the second positive electrode active material layer disappears without a boundary. Therefore, the first positive electrode active material layer and the second positive electrode active material layer can be integrated without an interface therebetween, forming a single positive electrode active material layer.

[0151] Additionally, the WIP process may be performed at a temperature of 50°C to 90°C and a pressure of 300 MPa to 700 MPa.

[0152]

[0153] If the temperature of the WIP process is less than 50°C, it may be difficult for the first positive electrode active material layer and the second positive electrode active material layer to be integrated without an interface, and if it is more than 90°C, the temperature may be too high, causing damage to the first positive electrode active material layer and the second positive electrode active material layer. Specifically, the temperature of the WIP process may be 50°C or higher, 55°C or higher, 55°C or higher, 60°C or higher, or 65°C or higher, and may be 90°C or lower, 85°C or lower, or 80°C or lower.

[0154] In addition, if the pressure of the WIP process is less than 300 MPa, it may be difficult for the first positive electrode active material layer and the second positive electrode active material layer to be integrated without an interface, and if it exceeds 700 MPa, the temperature may be too high, causing damage to the first positive electrode active material layer and the second positive electrode active material layer. Specifically, the pressure of the WIP process may be 300 MPa or more, 350 MPa or more, 400 MPa or more, or 450 MPa or more, and may be 700 MPa or less, 650 MPa or less, 600 MPa or less, or 550 MPa or less.

[0155] In addition, the cathode and the solid electrolyte membrane are as described below.

[0156]

[0157] All-solid-state batteries

[0158] The present invention also relates to an all-solid-state battery.

[0159] An all-solid-state battery according to the present invention includes the positive electrode, the negative electrode, and a solid electrolyte membrane interposed therebetween.

[0160]

[0161] In one embodiment of the present invention, the positive electrode may be an all-solid-state battery positive electrode as described above. In the positive electrode, the second positive electrode active material layer may be in contact with one surface of the solid electrolyte membrane.

[0162]

[0163] In one embodiment of the present invention, the negative electrode may include a negative current collector; and a negative active material layer formed on the negative current collector, and the negative active material layer may be laminated so as to be in contact with the solid electrolyte layer. Alternatively, the negative electrode layer may include a negative current collector; and a non-cathode coating layer formed on the negative current collector, and the non-cathode coating layer may be laminated so as to be in contact with the solid electrolyte layer.

[0164]

[0165] The above negative active material is lithium (Li + ) can be reversibly intercalated or deintercalated, a material that can react with lithium ions to form a reversibly lithium-containing compound, or a lithium metal or a lithium alloy.

[0166] The above lithium ion (Li + ) can be reversibly inserted or de-inserted, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The lithium ion (Li + ) can be, for example, tin oxide, titanium nitrate or silicon. The lithium alloy can be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al) and tin (Sn).

[0167] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), and specifically, may be in the form of lithium metal or lithium and a thin film or a lithium-indium alloy thin film or powder.

[0168] The negative electrode active material may be included in an amount of 40 to 80 wt% based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt% or more or 50 wt% or more, and 70 wt% or less or 80 wt% or less. If the content of the negative electrode active material is less than 40 wt%, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80 wt%, the material transfer resistance may increase.

[0169] In addition, the binder is a component that assists in the bonding of the negative electrode active material and the conductive material and the bonding to the negative electrode current collector, and includes styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose It may include at least one selected from the group consisting of acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0170] In addition, the binder may be included in an amount of 0.5 wt% to 10 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, 2 wt% or more, 3 wt% or more, 4 wt% or more, or 5 wt% or more, and 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, or 6 wt% or less. If the content of the binder is less than 0.5 wt%, the adhesive strength between the negative electrode active material and the negative electrode current collector may be reduced, and if it exceeds 10 wt%, the adhesive strength may be improved, but the content of the negative electrode active material may be reduced, which may lower the battery capacity.

[0171]

[0172] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery, and has excellent electrical conductivity. Representative examples thereof include graphite or conductive carbon, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; metal powder such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more thereof, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0173] The conductive material may typically be included in an amount of 1 wt% to 10 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 2 wt% or more, 3 wt% or more, 4 wt% or more, or 5 wt% or more, and 10 wt% or less, 9 wt% or less, 8 wt% or less, 7 wt% or less, or 6 wt% or less. If the content of the conductive material is too low, such as less than 1 wt%, it may be difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 10 wt%, too much, the amount of the negative electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the negative electrode is not particularly limited, and a conventional method known in the art, such as mixing with the negative electrode active material or coating, may be used.

[0174] In addition, the negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. In addition, the negative electrode current collector, like the positive electrode current collector, may be made of various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc. having fine irregularities formed on the surface.

[0175]

[0176] In addition, the non-cathode coating layer does not contain a negative electrode active material, and a negative electrode active material may be formed in the non-cathode coating layer by charging. For example, when the battery is charged, lithium ions may move from the positive electrode and lithium metal may be precipitated from the negative electrode. In other words, the non-cathode coating layer may be a film that induces lithium precipitation.

[0177] The above-mentioned cathode-free coating layer may include metal compound particles and carbon material particles, and specifically, may include a carbon material-metal composite.

[0178] The above carbon material particles may be, for example, amorphous carbon material particles. However, the carbon material particles are not limited to amorphous particles. Specific examples of the above amorphous carbon material include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or combinations thereof.

[0179] In addition, the metal particles used in the metal compound particles may be particles that form an alloy with lithium, and the metal particles may be at least one type of particle selected from silver (Ag), gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc. The non-cathode coating layer may be formed as a very thin film with a micro-thickness, and may be formed with a thickness of, for example, 10 μm or less.

[0180] Preferably, the non-cathode coating layer may include an Ag-C composite as a carbon material-metal composite, and upon first charging, lithium may be precipitated between the negative electrode current collector and the coating layer including the Ag-C composite.

[0181]

[0182] The method for manufacturing the above negative electrode is not particularly limited, and can be manufactured by forming a negative electrode active material layer on the negative electrode current collector using a method for forming a layer or film commonly used in the art. For example, methods such as compression, coating, and deposition can be used. In addition, a case in which a battery is assembled on the negative electrode current collector without a lithium thin film and then a metallic lithium thin film is formed on the metal plate through initial charging is also included in the negative electrode of the present invention.

[0183]

[0184] In one embodiment of the present invention, the solid electrolyte membrane may include at least one selected from the group consisting of a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

[0185] The above sulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0186] <Chemical Formula 1>

[0187] L a1 M b1 P c1 S d1 A e1

[0188] In the above chemical formula 1, L is an element selected from Li, Na, and K, M is an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge, A represents I, Br, Cl, or F, and a1 to e1 represent the composition ratio of each element, with a1: b1:c1:d1:e1 being 1 to 12:0 to 1:1:2 to 12:0 to 5.

[0189] For example, the above sulfide-based solid electrolyte may be an LPS-type sulfide containing sulfur and phosphorus, an LPSCl-type sulfide, or Li 4-x Ge 1-x P x S4 (x is 0.1 to 2, specifically x is 3 / 4, 2 / 3), Li 10±1 MP2X 12 (M=Ge, Si, Sn, Al, X=S, Se), Li 3.833 Sn 0.833 As 0.166 S4, Li4SnS4, Li 3.25 Ge 0.25 P 0.75S4, Li2S-P2S5, B2S3-Li2S, xLi2S-(100-x)P2S5 (x is 70 to 80), Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiBr-P2S5, Li2S-LiCl-P2S5, Li2S-Li2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SnS, Li2S-P2S5-Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-SiS2-Li3N, Li2S-SiS2-LiI, Li2S-B2S3-LiI, etc., but It is not necessarily limited. For example, the LPSCl type sulfide may be Li6PS5Cl.

[0190] In addition, the oxide-based solid electrolyte may be represented by the following chemical formula 2:

[0191] <Chemical Formula 2>

[0192] Li 1+x+y Al x Ti 2-x Si y P 3-y O 12

[0193] (In the above chemical formula 2, x is 0≤ x ≤2, and y is 0≤ y ≤3.)

[0194] For example, the above oxide-based solid electrolyte is Li 3x La 2 / 3-x LLT system with perovskite structure such as TiO3, Li 14 LISICON, Li such as Zn(GeO4)4 1.3 Al 0.3 Ti 1.7 LATP series such as (PO4)3, (Li 1+x Ge 2-x Al x LAGP systems such as (PO4)3) and phosphate systems such as LiPON can be appropriately selected and used, but are not necessarily limited thereto.

[0195] Additionally, the solid electrolyte may be in an amorphous or crystalline state. Additionally, it may be in a mixed amorphous and crystalline state.

[0196] In addition, the solid electrolyte membrane may further include a binder. Examples of the binder material include resins such as styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polyacrylic acid. The binder material may be the same as or different from the material constituting the binder in the positive electrode active material layer and the negative electrode active material layer.

[0197]

[0198] battery module

[0199] The present invention also relates to a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0200] At this time, specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), etc.; an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system.

[0201] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0202]

[0203] Unit: wt%Example 1Example 2Example 3Comparative Example 1Comparative Example 2First positive electrode active material layerFirst positive electrode active material8080808080First solid electrolyte18.318.317.518.318.3First conductive agent0.20.210.20.2First binder1.51.51.51.51.5Second positive electrode active material layerSecond positive electrode active material8080808080Second solid electrolyte17.516.518.317.516.5Second conductive agent120.212Second binder1.51.51.51.51.5After laminating the first and second positive electrode active material layers, whether or not WIP process is performed○○○XX

[0204]

[0205] Example 1

[0206] (1) Formation of the first positive electrode active material layer

[0207] A first mixture was obtained by mixing 80 wt% of the first cathode active material NMC (NMC811, LGChem), 18.3 wt% of the first solid electrolyte Li6PS5Cl powder, 0.2 wt% of the first conductive material carbon nanotube, and 1.5 wt% of the first binder PTFE particles (polytetrafluoroethylene, Chemours) in a mortar.

[0208] The first mixture was subjected to 80 sheeting / calendaring loops using a roll press at a temperature of 20°C and under biaxial orientation conditions to produce a first positive electrode active material layer having a thickness of 100 μm.

[0209]

[0210] (2) Formation of the second positive electrode active material layer

[0211] A second mixture was obtained by mixing 80 wt% of NMC (NMC811, LGChem) as a second positive electrode active material, 17.5 wt% of Li6PS5Cl powder as a second solid electrolyte, 1 wt% of carbon nanotubes as a second conductive material, and 1.5 wt% of PTFE particles (polytetrafluoroethylene, Chemours) as a second binder in a mortar.

[0212] The second mixture was subjected to 80 first sheeting / calendering loops using a roll press under conditions of a temperature of 20°C and biaxial orientation to produce a second positive electrode active material layer having a thickness of 100 μm.

[0213]

[0214] (3) Formation of positive electrode active material layer

[0215] After laminating the first positive electrode active material layer on one side of the Al foil, which is the positive electrode current collector, the second positive electrode active material layer was laminated on one side of the first positive electrode active material layer, thereby obtaining a positive electrode laminate. The loading amount of the positive electrode was set to 8.2 mAh / cm2.

[0216]

[0217] (4) WIP process implementation

[0218] A sulfide-based solid electrolyte membrane containing LPSCl was laminated on one surface of the above-described positive electrode laminate, and a lithium negative electrode was laminated on one surface of the above-described solid electrolyte membrane, followed by isostatic pressing (WIP). At this time, the second positive electrode active material layer included in the positive electrode laminate was brought into contact with the above-described solid electrolyte membrane.

[0219] The above warm isostatic pressing (WIP) was performed at a temperature of 80°C and a pressure of 500 MPa (Fig. 2).

[0220]

[0221] Example 2

[0222] The same method as Example 1 was performed, except that the content of the second solid electrolyte in the second positive electrode active material layer was set to 16.5 wt% and the content of the second conductive material was set to 2 wt%.

[0223]

[0224] Example 3

[0225] The same method as Example 1 was performed, except that the content of the first conductive agent and the second conductive agent was set to 1 wt% and 0.2 wt%, respectively, and that the content of the first conductive agent included in the first positive electrode active material layer adjacent to the positive electrode current collector was set to be greater than the content of the second conductive agent.

[0226]

[0227] Comparative Example 1

[0228] After laminating a cathode on one side of a solid electrolyte membrane, warm isostatic pressing (WIP) was performed. At this time, the solid electrolyte membrane and the cathode active material layer were in contact.

[0229] Thereafter, a positive electrode laminate was laminated on the other side of the solid electrolyte membrane, thereby manufacturing an all-solid-state battery. At this time, the solid electrolyte membrane and the second positive electrode active material layer included in the positive electrode laminate were in contact. In addition, the composition and manufacturing method of the first positive electrode active material layer and the second positive electrode active material layer, the positive electrode laminate manufacturing method, the solid electrolyte membrane, and the negative electrode were the same as in Example 1, and the WIP process conditions were also the same as in Example 1 (Fig. 3).

[0230]

[0231] Comparative Example 2

[0232] The same method as Comparative Example 1 was performed, except that the content of the second solid electrolyte in the second positive electrode active material layer was set to 16.5 wt% and the content of the second conductive material was set to 2 wt%.

[0233]

[0234] Experimental Example 1: Confirming the Internal Structure of the Anode

[0235] The internal structure was confirmed by observing the cross-sections of the positive electrode and all-solid-state battery manufactured in Example 1 and Comparative Example 1. A scanning electron microscope (SEM, JEOL FESEM J05 (IT-800SHL)) and an energy dispersive spectrometer (EDS, Oxford AZtec) were used.

[0236]

[0237] FIG. 4a and FIG. 4b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result for a cross-section of an all-solid-state battery manufactured in Example 1.

[0238] FIG. 5a and FIG. 5b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result of a cross-section of a bonding surface of a first positive electrode active material layer and a second positive electrode active material layer included in a positive electrode of an all-solid-state battery manufactured in Example 1 of the present invention.

[0239] Figures 6a and 6b are photographs showing a scanning electron microscope (SEM) photograph and an energy-dispersive X-ray spectroscopy (EDS) result for a cross-section of an all-solid-state battery manufactured in Comparative Example 1.

[0240]

[0241] As shown in FIGS. 4a and 4b and FIGS. 5a and 5b, in the positive electrode and all-solid-state battery manufactured in Example 1, there is no boundary separating the first positive electrode active material layer (121) and the second positive electrode active material layer (122), so that it can be seen that a substantially integrated positive electrode active material layer (20) is formed.

[0242] On the other hand, as shown in FIGS. 6a and 6b, in the positive electrode and all-solid-state battery manufactured in Comparative Example 1, an interface (I) separating the first positive electrode active material layer (121) and the second positive electrode active material layer (122) was clearly observed (6a: x350; 6b: x2.00k).

[0243]

[0244] Example 1 and Comparative Example 1 differ in the presence or absence of a WIP process after laminating the first positive electrode active material (121) and the second positive electrode active material layer (122). It was confirmed that in Example 1, the boundary separating the first positive electrode active material (121) and the second positive electrode active material layer (122) disappears through the WIP process performed after laminating them, thereby forming an integrated positive electrode active material layer (20).

[0245]

[0246] Experimental Example 2: Battery Performance Measurement

[0247] The capacity capability of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 was observed through a protocol of activating them in a charger / discharger at 0.05 C for 2 cycles and then discharging them up to 1 C.

[0248]

[0249] Figure 7 is a graph showing the initial charge / discharge characteristics of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.

[0250] As shown in Fig. 7, it was confirmed that the initial charge / discharge characteristics of the all-solid-state batteries of Examples 1 and 2 were superior to those of the all-solid-state batteries of Comparative Examples 1 and 2.

[0251]

[0252] In addition, experiments were conducted on the performance of all-solid-state batteries according to the content of the conductive material included in the first and second positive electrode active material layers. Example 1 is an all-solid-state battery having a large content of the second conductive material included in the second positive electrode active material layer, and Example 3 is an all-solid-state battery having a large content of the first conductive material included in the first positive electrode active material layer.

[0253] Figures 8a and 8b are graphs showing the initial charge / discharge characteristics and output characteristics of the all-solid-state batteries manufactured in Examples 1 and 3, respectively.

[0254] As shown in FIG. 8a and FIG. 8, it was confirmed that the charge / discharge characteristics and output characteristics of the all-solid-state battery manufactured in Example 3 were better than those of Example 1. Specifically, it was confirmed that the initial capacities of Examples 1 and 3 were 183.8 mAh / g and 182.5 mAh / g, respectively, and the 1.0C rate was 40.8% and 72.8%, respectively.

[0255]

[0256] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0257]

[0258] [Explanation of symbols]

[0259] 100: Bipolar

[0260] 110: Positive current collector

[0261] 120: Positive electrode active material layer

[0262] 121: First positive electrode active material layer

[0263] 122: Second positive electrode active material layer

[0264] 200: Cathode

[0265] 210: Negative current collector

[0266] 220: Negative active material layer

[0267] 300: Solid electrolyte membrane

[0268] I: Interface between the first positive electrode active material layer and the second positive electrode active material layer

Claims

1. A positive electrode for an all-solid-state battery, comprising: a positive electrode current collector; and a positive electrode active material layer formed on one surface of the positive electrode current collector; The positive electrode active material layer includes a first positive electrode active material layer in contact with one surface of the positive electrode current collector; and a second positive electrode active material layer formed on one surface of the first positive electrode active material layer; The first positive electrode active material layer includes a first positive electrode active material, a first solid electrolyte, a first conductive material, and a first fibrous binder, and the second positive electrode active material layer includes a second positive electrode active material, a second solid electrolyte, a second conductive material, and a second fibrous binder. The first positive electrode active material layer and the second positive electrode active material layer are integrated without an interface therebetween, The contents of the first solid electrolyte and the second solid electrolyte are different, The contents of the first and second conductive agents are different, A positive electrode for an all-solid-state battery, wherein the first positive electrode active material layer and the second positive electrode active material layer are solvent-free.

2. In paragraph 1, The content of the first solid electrolyte is 10 to 25 wt% based on the total weight of the first positive electrode active material layer, A positive electrode for an all-solid-state battery, wherein the content of the second solid electrolyte is 10 to 25 wt% based on the total weight of the second positive electrode active material layer.

3. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer is 1:4 to 4:

1.

4. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the thickness of the positive electrode active material layer is 50 to 500 ㎛.

5. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the porosity of the first positive electrode active material layer is 8% to 20%, and the porosity of the second positive electrode active material layer is 8% to 20%.

6. In paragraph 1, An all-solid-state battery positive electrode, wherein the first fibrous binder and the second fibrous binder each include at least one selected from the group consisting of polytetrafluoroethylene (PTFE), ethylene-vinyl acetate (EVA), styrene-ethylene-butylene-styrene (SEBS), and copolymers containing the same.

7. In paragraph 1, An all-solid-state battery positive electrode, wherein the first solid electrolyte and the second solid electrolyte each include at least one selected from the group consisting of a sulfide-based solid electrolyte and an oxide-based solid electrolyte.

8. In paragraph 1, An all-solid-state battery positive electrode, wherein the first conductive material and the second conductive material each include at least one linear conductive material selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers.

9. In paragraph 1, The loading of the above positive electrode is 6 mAh / cm 2 An ideal, all-solid-state battery cathode. 10.(S1) A step of forming a first positive electrode active material layer by mixing a first positive electrode active material, a first solid electrolyte, a first conductive agent, and a first binder and then forming the mixture into a film form using a first sheeting / calendaring process; (S2) A step of forming a second positive electrode active material layer by mixing a second positive electrode active material, a second solid electrolyte, a second conductive agent, and a second binder and then forming the mixture into a film shape through a second sheeting / calendering process; (S3) A step of sequentially laminating the first positive electrode active material layer and the second positive electrode active material layer on one side of the positive electrode current collector; and (S4) A method for manufacturing a positive electrode for an all-solid-state battery, comprising: sequentially stacking the positive electrode laminate, the solid electrolyte membrane, and the negative electrode obtained in the step (S3), and then performing warm isostatic pressing (WIP) to integrate the first positive electrode active material layer and the second positive electrode active material layer included in the positive electrode laminate.

11. In paragraph 10, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the first calendaring process and the second calendaring process are each performed at a temperature of 20°C to 200°C for 1 to 50 loops.

12. In paragraph 10, A method for manufacturing a positive electrode for an all-solid-state battery, wherein the above-mentioned isostatic pressing is performed at a temperature of 50°C to 90°C and a pressure of 300 MPa to 700 MPa.

13. An all-solid-state battery comprising a positive electrode, a negative electrode and a solid electrolyte membrane interposed therebetween according to any one of claims 1 to 9.

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