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

Abstract

The present invention relates to a positive electrode for an all-solid-state battery. More specifically, the invention comprises a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode current collector comprises a main body portion and a positive electrode tab protruding in one direction from the main body portion, and the positive electrode active material layer comprises a first layer provided on the main body portion and a second layer on the first layer, and each of the first layer and the second layer may comprise a positive electrode active material, a solid electrolyte, and a binder. The binder content of the first layer is greater than the binder content of the second layer, and the second layer comprises a first region adjacent to the positive electrode tab and a second region remaining excluding the first region, wherein the binder content of the first region is greater than the binder content of the second region, and the ratio of the area of ​​the first region to the area of ​​the second region may be 1:9 to 4:6.

Description

Technology Field

[0001] This is about all-solid-state batteries. Background Technology

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and stability is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Recently, all-solid-state batteries in which liquid electrolytes are replaced with solid electrolytes have been proposed. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes. The problem to be solved

[0005] The problem that the present invention aims to solve is to improve the electrochemical balance of a positive electrode for an all-solid-state battery and enhance lifespan characteristics by designing a multilayer electrode plate and controlling the composition of the electrode plate. means of solving the problem

[0007] A positive electrode for an all-solid-state battery according to the concept of the present invention comprises a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode current collector comprises a main body portion and a positive electrode tab protruding in one direction from the main body portion, and the positive electrode active material layer comprises a first layer provided on the main body portion and a second layer on the first layer, and each of the first layer and the second layer may comprise a positive electrode active material, a solid electrolyte, and a binder. The binder content of the first layer is greater than the binder content of the second layer, and the second layer comprises a first region adjacent to the positive electrode tab and a second region remaining excluding the first region, wherein the binder content of the first region is greater than the binder content of the second region, and the ratio of the area of ​​the first region to the area of ​​the second region may be 1:9 to 4:6.

[0008] A method for manufacturing an anode for an all-solid-state battery according to another concept of the present invention may comprise: forming a first active material region on a metal substrate; forming a second active material region and a third active material region on the first active material region, arranged parallel to each other in the width direction of the metal substrate; drying the first, second, and third active material regions to form an anode sheet, wherein each of the first, second, and third active material regions comprises an anode active material, a solid electrolyte, and a binder; and cutting the anode sheet to form an anode composite layer. The anode sheet comprises a first non-active portion formed on one side thereof, and the second active material region is adjacent to the first non-active portion in the width direction, and the anode composite layer comprises an electrode tab formed by cutting the first non-active portion, a first anode active material layer including the first active material region, and a second anode active material layer including the second and third active material regions, wherein the binder content of the second active material region is smaller than the binder content of the first active material region, and the binder content of the third active material region may be smaller than the binder content of the second active material region.

[0009] A solid-state battery according to another concept of the present invention may include: the positive electrode; a negative electrode comprising a negative current collector and a negative coating layer on the negative current collector; and a solid electrolyte layer between the positive electrode and the negative electrode. Effects of the invention

[0011] According to one aspect, the stability and lifespan of the battery can be improved by improving the electrochemical balance of the electrodes.

[0012] According to another aspect, short circuits can be prevented by minimizing resistance and preventing irreversible precipitation through the design of the electrodes. Brief explanation of the drawing

[0014] FIGS. 1 and FIGS. 2 are plan views of a positive electrode for an all-solid-state battery according to an embodiment of the present invention. Figure 3 is a cross-sectional view along the line A-A' of Figure 1. Figure 4 is an enlarged view of the M region of Figure 3. FIG. 5 is a cross-sectional view of a positive electrode for an all-solid-state battery according to one embodiment of the present invention. FIGS. 6 and FIGS. 7 are cross-sectional views of an all-solid-state battery unit cell according to an embodiment of the present invention. FIGS. 8 to 12 illustrate a method for manufacturing an anode according to an embodiment of the present invention. Figure 13 is a photograph showing the appearance of an all-solid-state battery according to a comparative example. Specific details for implementing the invention

[0015] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0016] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0017] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0018] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0019] In this specification, "combination of these" may mean a mixture of components, a laminate, a composite, a copolymer, an alloy, a blend, and a reaction product, etc.

[0020] Unless otherwise defined in this specification, the particle size may be the average particle size. Additionally, the particle size refers to the average particle size (D50), which means the diameter of the particle whose cumulative volume in the particle size distribution is 50% by volume. The average particle size (D50) may be measured by methods widely known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) image or a scanning electron microscope (SEM) image. Alternatively, the average particle size (D50) value may be obtained by measuring using a measuring device utilizing dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and then calculating from this. Alternatively, it may be measured using a laser diffraction method. When measuring by laser diffraction, more specifically, after dispersing the particles to be measured in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasound of about 28 kHz at an output of 60 W, and then the average particle size (D50) at 50% of the particle size distribution in the measuring device can be calculated.

[0021] In this specification, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0023] All-solid-state battery

[0024] An all-solid-state battery according to an embodiment of the present invention may include a unit cell. A unit cell may refer to a minimum unit for operating the battery. A unit cell may include a minimum component of an all-solid-state battery. That is, a unit cell may include a positive electrode, a negative electrode, and a solid electrolyte layer between the positive and negative electrodes. In some cases, the unit cell may further include an additional functional layer, such as an adhesion-enhancing layer, disposed between the positive electrode and the solid electrolyte layer or between the negative electrode and the solid electrolyte layer. An all-solid-state battery may include a plurality of unit cells.

[0025] FIGS. 1 and 2 are plan views of a positive electrode (CSH) according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the positive electrode (CSH) along the line A-A' of FIG. 1. FIG. 4 is an enlarged view of region M of FIG. 3. A positive electrode (CSH) according to an embodiment of the present invention may include a positive electrode current collector (COL1) and a positive electrode active material layer (CML) disposed on the positive electrode current collector (COL1). The positive electrode active material layer (CML) may include a positive electrode active material (CAC), a solid electrolyte (SEP), and a binder (BID). Although not illustrated, the positive electrode active material layer (CML) may further include a conductive material.

[0026] The positive current collector (COL1) can provide a reference surface on which the positive active material layer (CML) is placed. The positive current collector (COL1) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0027] To increase the bonding strength between the positive current collector (COL1) and the positive active material layer (CML), a carbon-containing layer with a thickness of 0.1 μm to 4 μm, or 1 μm to 3 μm, may be further disposed between the positive current collector (COL1) and the positive active material layer (CML). As an example, the carbon-containing layer may contain a relatively large amount of binder. The carbon-containing layer can improve the adhesion strength between the positive current collector (COL1) and the positive active material layer (CML) while simultaneously improving the conductivity of the positive (CSH).

[0028] The positive active material (CAC) of the positive active material layer (CML) may include a material capable of reversibly absorbing and desorbing lithium ions. The positive active material (CAC) may include a plurality of particles. The positive active material (CAC) may include, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each positive active material (CAC) may be a single material or a mixture of two or more materials.

[0029] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c(0≤b≤0.5, 0≤c≤0.05), Li a Nor 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor 1-b-c Mn b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-fJ2(PO4)3(0≤f≤2), Li 3-f It is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0030] The cathode active material (CAC) may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNix Co y Mn z O2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극 활물질(CAC)이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 단위셀의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0031] The aforementioned compound contained in the positive electrode active material (CAC) may be covered by a coating layer (not shown). The positive electrode active material (CAC) may also be a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material (CAC) may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material (CAC). The method for forming the coating layer is, for example, spray coating or immersion.

[0032] When the cathode active material (CAC) is a ternary lithium transition metal oxide, such as NCA or NCM, containing nickel (Ni), it is possible to increase the capacity density of the unit cell and reduce the leaching of metal from the cathode active material in the charged state. Consequently, the cycle characteristics of the unit cell in the charged state are improved. Meanwhile, "cycle characteristics" refers to the degree of degradation of the unit cell due to charging and discharging; unit cells with high cycle characteristics experience less degradation due to charging and discharging, while unit cells with low cycle characteristics may experience greater degradation.

[0033] The positive active material (CAC) may have particle shapes such as spheres or ellipsoids. The particle size and content of the positive active material (CAC) are not particularly limited. For example, the average particle size of the positive active material (CAC) analyzed by scanning electron microscope (SEM) images may be 200 nm to 25 µm.

[0034] The solid electrolyte (SEP) of the positive electrode active material layer (CML) may have a particulate shape. The solid electrolyte (SEP) may be dispersed among the positive electrode active materials (CAC). The solid electrolyte (SEP) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS 6-x I x It may include at least one of (0≤x≤2).

[0035] Sulfide-based solid electrolytes are, for example, Li 7-x PS6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising at least one of (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I.

[0036] Alternatively, sulfide-based solid electrolytes are Li 7-a-c M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, 0≤c≤2). Here, X may be F, Br, Cl, I, or a combination thereof. M can be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. there is.

[0037] The density of the azyrodite-type solid electrolyte (SEP) may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte (SEP), the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte (SEP) may be, for example, 15 GPa to 35 GPa.

[0038] The average particle size of the solid electrolyte (SEP) in the positive active material layer (CML) may be smaller than that of the solid electrolyte in the solid electrolyte layer described later. For example, the average particle size of the solid electrolyte (SEP) in the positive active material layer (CML) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size of the solid electrolyte in the solid electrolyte layer. Meanwhile, the average particle size may be the median diameter measured using a laser particle size distribution meter.

[0039] The positive active material layer (CML) may further include a binder (BID). The binder (BID) can bind the positive active material (CAC), solid electrolyte (SEP), and conductive material within the positive active material layer (CML) together. The binder (BID) may include a material to improve the bonding strength between the positive active material layer (CML) and the positive current collector (COL1). The binder (BID) may include, for example, at least one of polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate.

[0040] The positive active material layer (CML) may further include a conductive material. The conductive material may provide conductivity without causing chemical changes in the unit cell, thereby increasing the conductivity of the positive active material (CAC) and the solid electrolyte (SEP). The conductive material may include a carbon-based material. The conductive material may include, for example, at least one of graphite, carbon black, acetylene black, carbon nanofibers, or carbon nanotubes.

[0041] In one embodiment, the content of the positive active material (CAC) with respect to the total weight of the positive active material layer (CML) may be 10 wt% to 99 wt%, 30 wt% to 80 wt%, 40 wt% to 70 wt%, 40 wt% to 50 wt%, 60 wt% to 90 wt%, or 70 wt% to 90 wt%.

[0042] In one embodiment, the content of the solid electrolyte (SEP) in the positive active material layer (CML) may be 10% to 70% by weight, 10% to 60% by weight, 5% to 30% by weight, 5% to 25% by weight, or 10% to 40% by weight of the total weight of the positive active material layer (CML).

[0043] The positive active material layer (CML) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the aforementioned positive active material (CAC), solid electrolyte (SEP), conductive material, and binder.

[0044] Hereinafter, an anode according to an embodiment of the present invention will be described in more detail with reference to the drawings. Referring to FIG. 1, the anode current collector (COL1) may include a main body portion (MBD) and an anode tab (CTB). The main body portion (MBD) may provide an area where an anode active material layer (CML) is disposed. The anode tab (CTB) may refer to an unprotected area protruding in one direction from the main body portion (MBD). That is, the anode active material layer (CML) may be provided on the main body portion (MBD) but may not be provided on the anode tab (CTB).

[0045] As shown in FIG. 1, when describing an embodiment in which the positive tab (CTB) protrudes in a second direction (D2), the main body (MBD) may include a first end (ED1) and a second end (ED2) facing each other in the second direction (D2). Each of the first end (ED1) and the second end (ED2) may represent one end of the main body (MBD). The first end (ED1) may cross the boundary between the positive tab (CTB) and the main body (MBD). That is, the positive current collector (COL1) may be separated into the main body (MBD) and the positive tab (CTB) based on the first end (ED1).

[0046] As shown in FIG. 2, even if the specific location of the positive tab (CTB) is different, the main body (MBD) and the positive tab (CTB) are distinguished based on the first end (ED1), and the positive tab (CTB) protrudes in the second direction (D2) in the same way.

[0047] The positive tab (CTB) is electrically connected to the lead tab and can be connected to the outside of the unit cell. The positive tab (CTB) can transmit the current generated from the positive electrode to an external circuit. The positive tab (CTB) can serve to provide a stable flow of current between the inside and outside of the unit cell. However, a problem of increased local current density may occur in the region of the positive active material layer (CML) adjacent to the positive tab (CTB).

[0048] Irreversible lithium precipitation may occur when the cathode active material (CAC) is used in a biased manner in a portion of the cathode active material layer (CML) adjacent to the cathode tab (CTB). This degrades the structural stability of the cathode (CSH) and can cause a short circuit. Furthermore, this problem may be exacerbated if the electrode loading amount or thickness is increased to improve the capacity of the all-solid-state battery.

[0049] Furthermore, when the loading amount of the anode (CSH) increases, the distribution of the binder (BID) within the anode (CSH) becomes uneven, which may lead to reduced adhesion with the anode current collector (COL1). This can cause the electrode plate to detach, thereby degrading the long-term lifespan characteristics of the battery. In particular, this problem can be further exacerbated when a dry process is used for anode manufacturing.

[0050] To address this, the embodiments of the present invention aim to maintain the overall electrochemical stability of the anode uniformly by controlling the compositional distribution within the anode through electrode structure design. Below, the anode according to the embodiments of the present invention will be described in detail, focusing on its structural features.

[0051] Referring to FIG. 3, the anode (CSH) according to an embodiment of the present invention may include a positive active material layer (CML) having a multilayer structure. For example, the positive active material layer (CML) may include a first layer (CML1) on a positive current collector (COL1) and a second layer (CML2) on the first layer (CML1). Each of the first layer (CML1) and the second layer (CML2) may include a positive active material (CAC), a solid electrolyte (SEP), and a binder (BID). The compositional ratio of the first layer (CML1) and the second layer (CML2) may differ from each other. The thicknesses of the first layer (CML1) and the second layer (CML2) may be the same or different.

[0052] In one embodiment of the present invention, the binder (BID) content of the first layer (CML1) may be greater than the binder (BID) content of the second layer (CML2). In this case, the binder (BID) content of the first layer (CML1) may refer to the weight ratio of the binder (BID) to the total weight of the first layer (CML1). By increasing the binder (BID) content of the first layer (CML1), the adhesion between the positive active material layer (CML) and the positive current collector (COL1) can be improved.

[0053] By improving the adhesion between the positive active material layer (CML) and the positive current collector (COL1), heat and resistance at the contact interface where current flow occurs can be reduced. In addition, the embodiment of the present invention can prevent the positive active material layer from detaching due to shrinkage / expansion during charging / discharging. In particular, when all components of a battery are made of solids, such as in an all-solid-state battery, mechanical stress due to volume change becomes a factor that impairs the stability of the electrode structure; therefore, it is even more important to improve the adhesion of the positive.

[0054] In one embodiment, the binder content of the first layer (CML1) may be 1 weight% or more, and the binder content of the second layer (CML2) may be less than 1 weight%. The binder content of the first layer (CML1) may be 1 weight% to 1.5 weight%. Within the above range, the first layer (CML1) can improve the bonding strength between the positive active material layer (CML) and the positive current collector (COL1), while simultaneously exhibiting proper performance as an active material layer.

[0055] In one embodiment, the binder (BID) content of the second layer (CML2) may be 0.4 wt% to 0.9 wt%. By including a relatively low amount of binder (BID) in the second layer (CML2), the ion conductivity between the positive active material layer (CML) and the solid electrolyte layer can be improved, and the energy density of the positive electrode can be increased.

[0056] Referring to FIG. 5, the positive active material layer (CML) according to an embodiment of the present invention comprises a first layer (CML1) and a second layer (CML2), wherein the second layer (CML2) may include a first region (AR1) adjacent to the positive tab (CTB) and a second region (AR2) excluding the first region (AR1). In this case, the composition of the first region and the second region may be different from each other.

[0057] In one embodiment, the binder content of the first region (AR1) may be greater than the binder content of the second region (AR2). By relatively increasing the binder content of the first region (AR1) adjacent to the positive electrode tab (CTB), the overall balance of the positive electrode active material layer (CML) can be improved, and lifespan characteristics, such as preventing short circuits, can be enhanced.

[0058] More specifically, a high current density may be formed in a portion of the positive electrode active material layer (CML) adjacent to the positive electrode tab (CTB). This increases the electrical load in that area and can consequently cause a localized temperature rise. This localized temperature rise not only degrades the stability of the battery but also poses a risk of causing the delamination of the positive electrode active material layer (CML).

[0059] To address this, increasing the binder (BID) content in the first region (AR1) can strengthen the bonding force between materials and improve mechanical stability. Specifically, by increasing the binder (BID) content in the first region (AR1), degradation and detachment that may occur in high current density regions can be mitigated, and interfacial degradation caused by temperature rise can be prevented. Consequently, by controlling the local input amount of binder (BID), the overall balance of the anode (CSH) can be maintained, and the lifespan characteristics and stability of the battery can be simultaneously improved.

[0060] According to an embodiment of the present invention, the area ratio of the first region (AR1) and the second region (AR2) of the second layer (CML2) may be in the range of 1:9 to 4:6. That is, the area of ​​the first region (AR1) may be in the range of 10% to 40% of the total area of ​​the second layer (CML2).

[0061] The above area ratio may be calculated based on the cross-sectional area of ​​a two-dimensional plane parallel to the positive current collector (COL1). For example, the area of ​​the first region (AR1) may refer to the area of ​​a plane formed by the first direction (D1) and the second direction (D2) (see FIG. 1 and FIG. 2).

[0062] If the area of ​​the first region (AR1) is less than 10%, the binder (BID) content in the second layer (CML2) becomes very low, which may reduce the bonding strength of the upper part of the positive active material layer (CML). This may reduce the bonding performance between the positive active material layer (CML) and the solid electrolyte layer. If the area of ​​the first region (AR1) exceeds 40%, the binder (BID) content of the entire positive active material layer (CML) increases, which may reduce the performance of the positive electrode, such as by decreasing the ion conductivity between the solid electrolyte layer and the positive active material layer. By having the first region (AR1) have an area within the above range, the aforementioned problems can be solved, and at the same time, appropriate physical properties as a positive active material layer can be provided.

[0063] In one embodiment, the binder content of the first region (AR1) may be 0.7 wt% to 0.9 wt%. The binder content of the second region (AR2) may be 0.4 wt% to 0.6 wt%.

[0064] The thicknesses of the first layer (CML1) and the second layer (CML2) may differ from each other. In one embodiment, the first layer (CML1) may be thinner than the second layer (CML2). Referring to the above description, by including the first layer (CML1) with a high binder content relatively thinly in the positive active material layer (CML), the bonding strength with the positive current collector can be improved, while the performance of the positive can be optimized. That is, the first layer (CML1) can function as a bonding layer of the positive active material layer (CML).

[0065] Referring again to FIGS. 1 to 3, the main body (MBD) may include a tap adjacent part (ADJ) adjacent to the positive tap (CTB). Specifically, the main body (MBD) may include a tap adjacent part (ADJ) extending from a first end (ED1) toward a second end (ED2). The tap adjacent part (ADJ) may be an area adjacent to the first end (ED1).

[0066] In one embodiment, the tab adjacent region (ADJ) may be defined as an area having 20% ​​of the total area of ​​the main body (MBD). That is, the tab adjacent region (ADJ) is an area extended from the first end (ED1) toward the second end (ED2) and may have an area of ​​approximately 20% of the area of ​​the main body (MBD).

[0067] In one embodiment, the tap adjacent portion (ADJ) may be an area having a constant width with respect to the second direction (D2). More specifically, the tap adjacent portion (ADJ) may refer to an area extending from the first end (ED1) toward the second end (ED2) by a second length (L2). That is, with respect to the second direction (D2), the width of the tap adjacent portion (ADJ) may be the second length (L2).

[0068] At this time, the area of ​​the tap adjacent portion (ADJ) may be the value obtained by multiplying the width of the first end portion (ED1) and the second length (L2). Based on the second direction (D2), the width of the main body portion (MBD) may be the first length (L1). When the width of the main body portion (MBD) in the first direction (D1) is constant, the value of the second length relative to the first length (L2 / L1) may be approximately 0.2.

[0069] Referring again to FIG. 3, the first region (AR1) may be located on the tap adjacent portion (ADJ). The area of ​​the first region (AR1) may match the area of ​​the tap adjacent portion (ADJ), but may differ. For example, part or all of the first region (AR1) may be included within a virtual cross-sectional area parallel to the tap adjacent portion (ADJ).

[0070] In one embodiment, the first region (AR1) may be vertically overlapped with the tab adjacent region (ADJ). By setting the binder content of the first region (AR1) on the tab adjacent region within the second layer to a high level, the bonding strength of the electrode plate in the region adjacent to the anode tab (CTB) can be improved. This prevents the binder from deforming due to heat and resistance caused by high current density, and improves the stability of the anode.

[0071] As described above, the cathode (CSH) according to an embodiment of the present invention can optimize the performance of the cathode by controlling the area and composition within the cathode active material layer (CML). Through the cathode active material layer (CML) having a multilayer structure, the performance and stability of a high-capacity thick-film electrode can be improved. Furthermore, it is possible to balance the overall performance of the electrode and improve its performance by controlling the binder content and area ratio of the first region (AR1) and the second region (AR2). This facilitates the design of a cathode that meets the various requirements of an all-solid-state battery. Consequently, by improving the stability and lifespan performance of the cathode (CSH), a high-performance all-solid-state battery can be provided.

[0072] Hereinafter, other components of an all-solid-state battery according to an embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIGS. 6 and 7 are cross-sectional views of a unit cell (CEL) according to embodiments of the present invention.

[0073] A unit cell (CEL) may include a positive electrode (CSH), a negative electrode (ASH), and a solid electrolyte layer (SEL) between the positive electrode (CSH) and the negative electrode (ASH). The positive electrode (CSH) may include a positive current collector (COL1) and a positive active material layer (CML) on the positive current collector (COL1). The negative electrode (ASH) may include a negative current collector (COL2) and a negative coating layer (AML) on the negative current collector (COL2). The negative current collector (COL2) may include a negative tab (ATB) protruding in one direction. The negative tab (ATB) may face in the same direction as the positive tab (CTB), but may be positioned in an opposite direction.

[0074] The cathode (ASH) may include a cathode current collector (COL2) and a cathode coating layer (AML) on the cathode current collector (COL2). The cathode current collector (COL2) may provide a reference surface on which the cathode coating layer (AML) is placed. The cathode current collector (COL2) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the cathode current collector (COL2) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the cathode current collector (COL2) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0075] The negative current collector (COL2) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (COL2) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (COL2) may be omitted.

[0076] Although not illustrated, the negative current collector (COL2) according to the embodiment may include a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon the occurrence of a short circuit, thereby interrupting battery operation and suppressing a sudden increase in current. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative current collector (COL2) may additionally include a metal piece and / or a lead tab. For more specific details regarding the base film, metal layer, metal chip, and lead tab of the negative current collector (COL2), refer to the anode current collector (110) described above. By having this structure, the negative current collector (COL2) can reduce the weight of the negative electrode (ASH) and, consequently, improve the energy density of the unit cell (CEL).

[0077] The negative electrode coating layer (AML) can be configured to allow lithium metal to grow between the unit cell (CEL) and the negative current collector (COL2) during charging. The negative electrode coating layer (AML) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0078] The cathode coating layer (AML) may include metal and carbon. For example, the cathode coating layer (AML) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The metal of the cathode coating layer (AML) can help lithium ions move toward the cathode current collector during charging and discharging of the all-solid-state battery.

[0079] The cathode coating layer (AML) may include at least one of amorphous carbon, crystalline carbon, or porous carbon. The cathode coating layer (AML) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. The carbon of the cathode coating layer (AML) can minimize volume change of the all-solid-state battery during charging and discharging and can provide structural stability of the cathode coating layer.

[0080] In one embodiment, the cathode coating layer (AML) may include a mixture (or composite) of carbon black and silver (Ag).

[0081] The thickness of the negative electrode coating layer (AML) may be smaller than that of the positive electrode active material layer (CML). The thickness of the negative electrode coating layer (AML) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (CML). The thickness of the negative electrode coating layer (AML) may be, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. If the thickness of the negative electrode coating layer (AML) is excessively thin, lithium dendrites formed between the negative electrode coating layer (AML) and the negative electrode current collector (COL2) may cause the negative electrode coating layer (AML) to collapse, thereby degrading the cycle characteristics of the unit cell (CEL). If the thickness of the cathode coating layer (AML) increases excessively, the energy density of the unit cell (CEL) decreases, and the internal resistance of the unit cell (CEL) due to the cathode coating layer (AML) increases, which may degrade the cycle characteristics of the cell.

[0082] The cathode coating layer (AML) may further include other additives in addition to metal and carbon. The cathode coating layer (AML) may further include at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion-conducting aids.

[0083] Meanwhile, although not illustrated, a carbon layer may be further included to improve adhesion between the cathode coating layer (AML) and the solid electrolyte layer (SEL).

[0084] In another embodiment, the negative electrode (ASH) of the unit cell (CEL) may further include a lithium metal layer (not shown) between the negative current collector (COL2) and the negative coating layer (AML). The thickness of the lithium metal layer may increase further during charging of the all-solid-state battery. The negative coating layer (AML) acts as a protective layer for the lithium metal layer and, at the same time, can suppress the growth of lithium dendrites from the lithium metal layer.

[0085] The lithium metal layer may be a thin metal film containing lithium or a lithium alloy. The lithium alloy is, for example, Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but is not limited to these; any alloy used as a lithium alloy is possible. The lithium metal layer may contain one of these alloys or lithium. Alternatively, the lithium metal layer may contain various types of alloys.

[0086] The lithium metal layer can serve as the negative electrode active material layer. That is, the negative electrode according to an embodiment of the present invention may use lithium or a lithium alloy as the negative electrode active material. The negative electrode active material may form a lithium metal layer or exist in a dispersed form within the negative electrode coating layer (AML). The negative electrode active material may exist within the lithium metal layer or the negative electrode coating layer (AML).

[0087] A solid electrolyte layer (SEL) may be provided between the positive electrode (CSH) and the negative electrode (ASH). The solid electrolyte layer (SEL) may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (SEL) may be the same as or different from any one of the materials included in the solid electrolyte (SEP) in the aforementioned positive electrode active material layer (CML).

[0088] The solid electrolyte may have particle shapes such as spheres or ellipsoids. For example, the average particle size of the solid electrolyte may be 1 μm to 20 μm, 1 μm to 15 μm, or 3 μm to 10 μm.

[0089] The solid electrolyte may include a sulfide-based solid electrolyte. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Additionally, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0090] In one embodiment, the solid electrolyte is Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), or Li 7-x PS 6-x I x It may include an argyrodite-type compound comprising at least one of (0≤x≤2). The solid electrolyte may include an argyrodite-type compound comprising at least one of Li6PS5Cl, Li6PS5Br, or Li6PS5I.

[0091] In another embodiment, the solid electrolyte is Li 7-a-c M a PS 6-c X c It may include an argyrodite-type compound comprising. Here, X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. a and c may each be real numbers between 0 and 2.

[0092] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0093] The solid electrolyte layer (SEL) may further include a binder. The binder included in the solid electrolyte layer (SEL) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. For example, the binder included in the solid electrolyte layer (SEL) may include at least one selected from the group consisting of styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polyacrylate. The binder of the solid electrolyte layer (SEL) may be the same as or different from the binder included in the positive active material layer (120) or the binder included in the coating layer (AML).

[0095] Method for manufacturing all-solid-state batteries

[0096] Hereinafter, a method for manufacturing an all-solid-state battery according to an embodiment of the present invention will be described. The manufacturing of an all-solid-state battery may include manufacturing a positive electrode, a negative electrode, and a solid electrolyte layer, respectively; however, this specification focuses on the method for manufacturing the positive electrode.

[0097] In particular, regarding the manufacturing process of an all-solid-state battery, excluding the method for manufacturing a positive electrode for an all-solid-state battery according to an embodiment of the present invention, methods commonly used in the industry may be freely applied.

[0098] A method for manufacturing an anode for an all-solid-state battery according to an embodiment of the present invention may include forming an active material region on a metal substrate; drying the active material region to form an anode sheet; and cutting the anode sheet to form an anode composite layer.

[0099] Referring to FIGS. 8 and 9, a metal substrate (MST) is transported in a first direction (D1), and an active material composition may be coated on the transported metal substrate (MST). A portion of the metal substrate (MST) may be defined as a coated area (CTA), and the remaining portion may be defined as an uncoated area (NCA). The uncoated area (NCA) may be formed at one end with respect to the width direction (D2) of the metal substrate (MST). For example, as shown in FIG. 8, the metal substrate (MST) may include an uncoated area (NCA) defined at the first end (WED1) with respect to the second direction (D2). As another example, the metal substrate (MST) may include an uncoated area (NCA) defined at the second end (WED2) opposite to the first end (WED1).

[0100] In this case, the active material region may be formed only in the coating region (CTA). That is, the non-coated region (NCA) may be defined as a region where the active material region is omitted. By leaving a portion of the metal substrate (MST) as the non-coated region (NCA), the convenience of electrode manufacturing can be improved. For example, the non-coated region (NCA) may be cut to form the electrode tab of the anode according to an embodiment of the present invention. The coating region (CTA) may be cut to form the main body of the anode according to an embodiment of the present invention.

[0101] By continuously coating an active material composition onto a metal substrate (MST) transported in the first direction (D1), the electrode production efficiency can be improved. Additionally, by coating active material compositions of different compositions, the composition of the anode active material layer to be manufactured can be easily designed. At this time, active material regions can be formed by considering the composition and structure of the anode to be manufactured. Furthermore, by controlling the area range where the anode active material regions of different compositions are coated, electrode design can be made even easier. In this way, by considering the shape and composition of the electrode to be manufactured from the step of coating the active material region on the metal substrate (MST), the productivity and yield of electrode manufacturing can be improved.

[0102] In one embodiment, referring to FIGS. 9 and 10, the active material region may include a first active material region (AMR1) on a metal substrate (MST). The first active material region (AMR1) may be formed on all or part of a coating region (CTA). Second and third active material regions (AMR2, AMR3) may be formed on the first active material region (AMR1). In this case, each of the first, second, and third active material regions (AMR1, AMR2, AMR3) may include a positive active material, a solid electrolyte, and a binder, but the composition ratios thereof may differ from each other.

[0103] In one embodiment, the binder content of the first active material region (AMR1) may be greater than the binder content of the second active material region (AMR2). The binder content of the second active material region (AMR2) may be greater than the binder content of the third active material region (AMR3). The binder content of the first active material region (AMR1) may be 1 wt% to 1.5 wt%. The binder content of the second active material region (AMR2) may be 0.7 wt% to 0.9 wt%. The binder content of the third active material region (AMR3) may be 0.4 wt% to 0.6 wt%.

[0104] The second active material region (AMR2) and the third active material region (AMR3) can be formed parallel to each other in the width direction (D2) on the first active material region (AMR1). Each of the second active material region (AMR2) and the third active material region (AMR3) can be formed on the first active material region (AMR1) with a constant width. The second active material region (AMR2) can have a first width (W1). The third active material region (AMR3) can have a second width (W2). The first width (W1) and the second width (W2) can be adjusted to suit the structure of the electrode to be manufactured. For example, the first width (W1) can be smaller than the second width (W2).

[0105] A metal substrate (MST) having a first active material region (AMR1) formed thereon is transported in a first direction (D1), and a second active material slurry (SD2) is coated with a constant width on the transported metal substrate (MST) to form a second active material region (AMR2). A third active material region (AMR3) can be formed by coating a third active material slurry (SD3) parallel to the second active material region (AMR2) with respect to the width direction (D2) of the metal substrate (MST). Through such a continuous process, it becomes easier to mass-produce a positive active material layer having a structure according to an embodiment of the present invention.

[0106] As described above, the metal substrate (MST) may include a non-active region (NCA) in which an active material region is omitted. The non-active region (NCA) may be formed on one side or both sides of the metal substrate (MST). In one embodiment, referring to FIG. 10, the metal substrate (MST) may include a first non-active region (NCA1) formed on one side. At this time, a second active material region (AMR2) may be adjacent to the first non-active region (NCA1) in the width direction (D2). The first active material region (AMR1) may be disposed at the base of the second and third active material regions (AMR2, AMR3).

[0107] That is, the metal substrate (MST) includes a first active material region (AMR1) on the coating region (CTA), and second and third active material regions (AMR2, AMR3) may be formed on the first active material region (AMR1). In this case, the second active material region (AMR2) is adjacent to the first uncoated portion (NCA1), and the first uncoated portion (NCA1), the second active material region (AMR2), and the third active material region (AMR3) may be arranged side by side in the width direction (D2) of the metal substrate (MST). In some cases, the metal substrate (MST) may further include a second uncoated portion formed on the opposite side of the first uncoated portion (NCA1). In this case, the third active material region (AMR3) may be adjacent to the second uncoated portion in the width direction (D2).

[0108] An anode sheet (CST) can be formed by drying an active material region on a metal substrate (MST). By drying the active material region, it can be used as an anode active material layer having a suitable thickness and physical properties.

[0109] A formed anode sheet (CST) can be cut to form an anode composite layer (CCL). The anode composite layer (CCL) formed by cutting the anode sheet (CST) can be used as a positive electrode for an all-solid-state battery. By cutting the anode sheet (CST) into an appropriate size and shape, a positive electrode for an all-solid-state battery can be provided.

[0110] For example, referring to FIG. 11, a cutting line (CTT) is provided to match the shape of the anode to be manufactured, and an anode sheet (CST) can be cut along the cutting line (CTT). At this time, the size and shape of the cutting line (CTT) can be adjusted to match the required capacity, size, or shape of the anode.

[0111] FIG. 12 illustrates an anode composite layer (CCL) of one embodiment formed by cutting an anode sheet (CST). By cutting the anode sheet (CST), a portion of the first non-existent portion (NCA1) may be cut. By cutting a portion of the first non-existent portion (NCA1), the anode composite layer (CCL) may form an anode tab (CTB). That is, the anode tab (CTB) of the anode composite layer (CCL) may be formed by cutting the first non-existent portion (NCA1). By cutting the anode sheet (CST), only a portion of the active material region may be separated. That is, the anode composite layer (CCL) may include an anode active material layer formed by cutting a portion of the active material region.

[0112] In one embodiment, the positive electrode composite layer (CCL) may include a first active material region (AMR1), a second active material region (AMR2), and a third active material region (AMR3). That is, the positive electrode composite layer (CCL) may include a positive electrode active material layer formed by cutting the first active material region (AMR1), the second active material region (AMR2), and the third active material region (AMR3).

[0113] The positive active material layer may have a double-layer structure comprising a first layer (CML1) including a first active material region (AMR1) and a second layer (CML2) including second and third active material regions (AMR2, AMR3). The thicknesses of the first layer (CML1) and the second layer (CML2) may be the same or different. For example, the thickness of the first layer (CML1) may be smaller than the thickness of the second layer (CML2).

[0114] In the second layer (CML2), the area of ​​the second active material region (AMR2) and the area of ​​the third active material region (AMR3) may differ from each other. By adjusting the area of ​​the second active material region (AMR2) and the area of ​​the third active material region (AMR3), an appropriate composition and structure of the positive active material layer can be designed.

[0115] Referring again to FIG. 11, the area of ​​the active material regions can be controlled through the size and shape of the cutting line (CTT). The final area ratio of the anode composite layer (CCL) can be controlled by controlling the area of ​​each of the first active material region (AMR1), the second active material region (AMR2), and the third active material region (AMR3) from the coating stage, but the final area ratio of the anode composite layer (CCL) can also be controlled by cutting the anode sheet (CST). For example, a cutting line (CTT) of the shape shown in FIG. 11 can maintain a constant width of the second active material region (AMR2) before and after cutting, but can reduce the width of the third active material region (AMR3).

[0116] In one embodiment, the area of ​​the second active material region (AMR2) is controlled during the step of forming the second active material region (AMR2) on the metal substrate, and the area of ​​the third active material region (AMR3) can be controlled by cutting the anode sheet (CST). The area of ​​the first active material region (AMR1) can also be controlled by cutting the anode sheet (CST). In the anode sheet (CST), the width (W1) of the second active material region may be relatively smaller than the width (W2) of the third active material region.

[0117] That is, the area ratio of the active material regions can be calculated based on the width of the active material regions. Specifically, referring to FIG. 12, the area ratio of the active material regions can be calculated as the width (W1) of the second active material region (AMR2) relative to the width (W3) of the positive active material layer based on the second direction (D2). The area and width of the first layer (CML1) and the second layer (CML2) in the positive active material layer can be substantially the same. That is, the area and width of the positive active material layer can be the same as the area and width of the second layer (CML2).

[0118] In one embodiment, the area of ​​the second active material region (AMR2) may be 10 to 40% of the total area of ​​the second layer (CML2). By adjusting the area of ​​the second active material region (AMR2), which has a high binder content, to the above range, the performance of the anode to be manufactured can be improved. By setting the binder content in the area adjacent to the anode tab (CTB) in the second layer (CML2) to be high, the bonding strength of the electrode plate can be improved.

[0119] As described above, the method for manufacturing an anode according to an embodiment of the present invention can optimize the design and performance of the anode by controlling the area and composition of the active material region on a metal substrate and cutting it. Specifically, by controlling the binder content and area ratio of the first active material region, the second active material region, and the third active material region, it is possible to balance the overall electrode and improve performance by considering the current density of the anode. Furthermore, according to the method for manufacturing an anode of the present invention, by realizing a multilayer structure of the anode active material layer, it is possible to facilitate the design of an anode that meets various requirements of an all-solid-state battery. Consequently, it contributes to improving the productivity and yield of the anode and can provide a high-performance all-solid-state battery.

[0121] The present invention will be explained in more detail below through embodiments. However, these embodiments are intended to illustrate the invention and the scope of the invention is not limited to these embodiments.

[0122] (Anode manufacturing)

[0123] LiNi as the positive active material 0.94 Co 0.04 Mn 0.02Particles of O2 with an average particle size of about 5 μm were prepared. As a solid electrolyte, an argyrodite-type crystal Li6PS5Cl with an average particle size of about 2 μm was prepared. PVdF-HFP was prepared as a binder. As a cathode slurry composition, a mixture of the aforementioned cathode active material, solid electrolyte, and binder was used.

[0124] Preparation Example 1: First anode composition

[0125] The first anode composition was prepared by mixing the anode active material: solid electrolyte: binder in a weight ratio of 85: 13.5: 1.5.

[0126] Preparation Example 2: Second anode composition

[0127] The first anode composition was prepared by mixing the anode active material: solid electrolyte: binder in a weight ratio of 92: 7.2: 0.8.

[0128] Preparation Example 3: Third Anode Composition

[0129] The first anode composition was prepared by mixing the anode active material: solid electrolyte: binder in a weight ratio of 92: 7.5: 0.5.

[0130] As will be described in detail below in the examples and comparative examples, the anode is manufactured by dry-coating an anode composition onto an anode current collector made of carbon-coated aluminum foil and applying pressure at about 10 MPa and 130°C for 10 minutes.

[0131] (Cathode manufacturing)

[0132] Carbon black (CB) was prepared as a carbon-based material and silver (Ag) particles were prepared as a metal particle. After mixing the carbon black and silver particles in a weight ratio of 3:1, 4 g of the mixed powder was placed in a container, and a mixed solution was prepared by adding 4 g of a methylpyrrolidone (NMP) solution containing 7 wt% of a polyvinylidene fluoride (PVDF) binder (Kureha # 9300).

[0133] A slurry was prepared by stirring the mixed solution while adding NMP little by little to the prepared mixed solution. The prepared slurry was applied to a SUS sheet using a bar coater, dried at 80°C in air for 10 minutes, and then vacuum dried at 40°C for 10 hours to produce a laminate. The surface of the prepared laminate was flattened by cold roll pressing to produce a cathode having a cathode coating layer / cathode current collector structure. At this time, the thickness of the cathode coating layer was approximately 15 μm, and the area of ​​the cathode coating layer and the cathode current collector were the same.

[0134] (Preparation of solid electrolyte layer)

[0135] A mixture was prepared by adding 98.5 parts by weight of Li6PS5Cl solid electrolyte, an argyrodite-type crystal, and 1.5 parts by weight of an acrylic binder. A slurry was prepared by stirring while adding octyl acetate to the prepared mixture. The prepared slurry was applied using a bar coater onto a 15 μm thick nonwoven fabric placed on a 75 μm thick PET substrate, and a laminate was prepared by drying in air at 80 °C for 10 minutes. A solid electrolyte layer was prepared by vacuum drying the prepared laminate at 80 °C for 2 hours.

[0136] (Assembly of all-solid-state batteries)

[0137] A solid electrolyte layer was placed on the cathode, and an anode was placed on the solid electrolyte layer. The prepared laminate was approximately 85 o Plate press treatment was performed at a pressure of 500 MPa for 30 min at C. This pressurization treatment sintered the solid electrolyte layer, improving battery characteristics. The thickness of the sintered solid electrolyte layer was approximately 45 μm.

[0138] An all-solid-state battery was manufactured by placing a pressurized laminate into a pouch and vacuum sealing it. Parts of the positive and negative current collectors were extended outside the sealed battery to be used as the positive terminal and negative terminal.

[0140] Example 1

[0141] A first positive active material layer was formed by coating the first positive composition of Preparation Example 1 onto a carbon-coated positive current collector. A second positive active material layer was formed by coating the second positive composition of Preparation Example 2 and the third positive composition of Preparation Example 3 onto the first positive active material layer. Specifically, the second positive composition was coated on the tab-adjacent portion, and the third positive composition was coated parallel to it in the width direction. At this time, the width direction is based on the direction in which the positive tab protrudes. That is, the second positive composition and the third positive composition are coated sequentially in order adjacent to the positive tab.

[0142] In the manufactured anode, the thickness of the first anode active material layer was about 50 μm, and the thickness of the second anode active material layer was about 50 μm. In addition, the anode was manufactured such that the area coated with the second anode composition was about 15% of the total area of ​​the second anode active material layer, and the area coated with the third anode composition was about 85%.

[0143] Example 2

[0144] An anode identical to Example 1 was manufactured, except that the area coated with the second anode composition was about 35% of the total area of ​​the second anode active material layer and the area coated with the third anode composition was about 65%.

[0145] Example 3

[0146] An anode identical to that of Example 1 was manufactured, except that the thickness of the first anode active material layer was about 30 μm and the thickness of the second anode active material layer was about 70 μm.

[0147] Example 4

[0148] An anode identical to that of Example 2 was manufactured, except that the thickness of the first anode active material layer was about 30 μm and the thickness of the second anode active material layer was about 70 μm.

[0150] Comparative Example 1

[0151] An anode identical to Example 1 was manufactured, except that the area coated with the second anode composition was about 5% of the total area of ​​the second anode active material layer and the area coated with the third anode composition was about 95%.

[0152] Comparative Example 2

[0153] An anode identical to Example 1 was manufactured, except that the area coated with the second anode composition was about 50% of the total area of ​​the second anode active material layer and the area coated with the third anode composition was about 50%.

[0155] All-solid-state batteries comprising the same negative electrode and solid electrolyte layer, except for the positive electrode being distinguished according to the above-described examples and comparative examples, were manufactured. The all-solid-state batteries according to the examples and comparative examples are summarized in Table 1 below.

[0156] 1st floor 2nd floor thickness Area ratio thickness Area of ​​the second composition Area of ​​the third composition Example 1 50μm 15% 85% 50μm Example 2 50μm 35% 65% 50μm Example 3 30μm 15% 85% 70μm Example 4 30μm 35% 65% 70μm Comparative Example 1 50μm 5% 95% 50μm Comparative Example 2 50μm 50% 50% 50μm

[0158] Evaluation Example 1: Battery Performance Evaluation

[0159] The performance of the all-solid-state battery according to the above-described examples and comparative examples was evaluated. Specifically, the first cycle was charged for 20 hours at a constant current of 0.05C until the battery voltage reached 4.2 V. Subsequently, discharge was performed for 20 hours at a current of 0.05C until the battery voltage reached 3.0 V.

[0160] The second cycle involved charging at a constant current of 0.1 C for 10 hours until the battery voltage reached 4.2 V. Subsequently, discharging was performed at a constant current of 0.1 C for 10 hours until the battery voltage reached 3.0 V.

[0161] After the second cycle, charging and discharging were performed for up to 100 cycles under the same conditions as the second cycle. The capacity retention rate was evaluated as shown in Equation 1 below.

[0162] [Mathematical Formula 1]

[0163] Capacity Retention Rate[%] = [n-th cycle discharge capacity / 1st cycle discharge capacity] × 100

[0164] Based on the initial charge / discharge capacity, the capacity after 100 cycles was evaluated. The results are shown in Table 2 below.

[0165] Dose retention rate (%) Example 1 92 Example 2 91 Example 3 95 Example 4 94 Comparative Example 1 - Comparative Example 2 80

[0166] Referring to the evaluation results above, it can be seen that the capacity retention rate of the all-solid-state battery according to the embodiments of the present invention is formed to be relatively high. This means that the cathode according to the embodiments of the present invention has its overall electrochemical balance optimized through the compositional design of the cathode active material layer, and consequently, its lifespan characteristics are improved.

[0167] In the case of Comparative Example 1, the capacity retention rate could not be evaluated because a short circuit occurred during the charging / discharging process. Referring to FIG. 13, the protruding part of the all-solid-state battery pouch of Comparative Example 1 can be seen. In addition, in the case of Comparative Example 2, reduced performance compared to the embodiments can also be seen.

[0168] In particular, in the case of Comparison 1, the area coated with the third anode composition occupies most of the area of ​​the second layer. As a result, the overall binder content of the second layer is reduced, and it is presumed that the above result was caused by the reduced binding force of the upper part of the anode active material layer in contact with the solid electrolyte layer.

Claims

Claim 1 A positive current collector; a positive active material layer on the positive current collector, wherein the positive current collector comprises a main body portion and a positive tab protruding in one direction from the main body portion, and the positive active material layer comprises a first layer provided on the main body portion and a second layer on the first layer, wherein each of the first layer and the second layer comprises a positive active material, a solid electrolyte, and a binder, wherein the binder content of the first layer is greater than the binder content of the second layer, and the second layer comprises a first region adjacent to the positive tab and a second region remaining excluding the first region, wherein the binder content of the first region is greater than the binder content of the second region, and the ratio of the areas of the first region and the second region is 1:9 to 4:6, a positive electrode for an all-solid-state battery. Claim 2 A positive electrode for an all-solid-state battery according to claim 1, wherein the binder content of the first layer is 1 weight% or more and the binder content of the second layer is less than 1 weight%. Claim 3 A positive electrode for an all-solid-state battery according to claim 1, wherein the binder content of the first layer is 1 weight% to 1.5 weight%. Claim 4 A positive electrode for an all-solid-state battery according to claim 1, wherein the binder content of the second layer is 0.4 weight% to 0.9 weight%. Claim 5 A positive electrode for an all-solid-state battery according to claim 4, wherein the binder content of the first region is 0.7 weight% to 0.9 weight%. Claim 6 A positive electrode for an all-solid-state battery according to claim 4, wherein the binder content of the second region is 0.4 weight% to 0.6 weight%. Claim 7 A positive electrode for an all-solid-state battery according to claim 1, wherein the thickness of the first layer is thinner than the thickness of the second layer. Claim 8 A positive electrode for an all-solid-state battery according to claim 1, wherein the main body comprises a first end and a second end facing each other in one direction, the first end crosses the boundary between the positive electrode tab and the main body, the main body comprises a tab adjacent portion extending from the first end toward the second end, and the first region vertically overlaps the tab adjacent portion. Claim 9 A positive electrode for an all-solid-state battery according to claim 1, further comprising a carbon coating layer between the positive current collector and the positive active material layer. Claim 10 In claim 1, the solid electrolyte is Li 7-a-c M a PS 6-c X c It comprises an argyrodite-type sulfide-based solid electrolyte represented by (0≤a≤2, 0≤c≤2), wherein X is F, Br, Cl, or a combination thereof, and M is scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), A positive electrode for an all-solid-state battery, which is indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof. Claim 11 A positive electrode for an all-solid-state battery according to claim 1, wherein the binder comprises at least one of polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, or polymethyl methacrylate. Claim 12 Forming a first active material region on a metal substrate; forming a second active material region and a third active material region on the first active material region, arranged parallel to each other in the width direction of the metal substrate; drying the first, second, and third active material regions to form an anode sheet, wherein each of the first, second, and third active material regions comprises an anode active material, a solid electrolyte, and a binder; A method for manufacturing an anode for an all-solid-state battery, comprising cutting the anode sheet to form an anode composite layer, wherein the anode sheet includes a first non-existent portion formed on one side thereof, and the second active material region is adjacent to the first non-existent portion in the width direction, and the anode composite layer includes an electrode tab formed by cutting the first non-existent portion, a first anode active material layer including the first active material region, and a second anode active material layer including the second and third active material regions, wherein the binder content of the second active material region is smaller than the binder content of the first active material region, and the binder content of the third active material region is smaller than the binder content of the second active material region. Claim 13 A method for manufacturing a positive electrode for an all-solid-state battery according to claim 12, wherein the binder content of the first active material region is 1% to 1.5% by weight. Claim 14 A method for manufacturing a positive electrode for an all-solid-state battery according to claim 12, wherein the binder content of the second active material region is 0.7 wt% to 0.9 wt% and the binder content of the third active material region is 0.4 wt% to 0.6 wt%. Claim 15 A method for manufacturing a positive electrode for an all-solid-state battery, wherein, in claim 12, the thickness of the first positive electrode active material layer is thinner than the thickness of the second positive electrode active material layer. Claim 16 A method for manufacturing an anode for an all-solid-state battery, wherein, in claim 12, a carbon layer is further formed on the metal substrate, and the first active material region is formed on the carbon layer. Claim 17 A method for manufacturing a positive electrode for an all-solid-state battery, wherein, in claim 12, the first active material region has an area of ​​10% to 40% of the total area of ​​the second positive electrode active material layer. Claim 18 An all-solid-state battery comprising: an anode according to claim 1; a cathode comprising a cathode current collector and a cathode coating layer on the cathode current collector; and a solid electrolyte layer between the anode and the cathode. Claim 19 In claim 18, the cathode coating layer comprises a carbonaceous material and metal particles, wherein the metal particles comprise at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), or zinc (Zn), and the carbonaceous material comprises at least one of amorphous carbon, crystalline carbon, or porous carbon, all-solid-state battery. Claim 20 In claim 18, an all-solid-state battery further comprising a lithium metal layer between the negative electrode current collector and the negative electrode coating layer, wherein the lithium metal layer comprises lithium metal or an alloy of lithium metal.

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