Method for manufacturing an electrode for an all-solid-state battery and electrode manufactured by the same

Abstract

A method for manufacturing an electrode for an all-solid-state battery is provided, comprising the steps of: preparing primary granules including an active material, a conductive material, and a binder; mixing the prepared primary granules with a solid electrolyte to prepare secondary granules coated with the solid electrolyte by a mechanofusion method; and coating the prepared secondary granules on a current collector to prepare an electrode. According to one embodiment of the present invention, the primary granules have an average particle diameter (D 50 ) is 50 μm to 110 μm, and the secondary granules have an average particle diameter (D 50 The electrode manufactured by the above manufacturing method improves the electrical network between the active material and the solid electrolyte, thereby contributing to the improvement of the performance of the battery when applied to an all-solid-state battery.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electrode for an all-solid-state battery and an electrode manufactured thereby. Specifically, the present invention relates to a method for manufacturing an electrode for an all-solid-state battery using secondary granules formed from primary granules by a mechanofusion method and an electrode manufactured thereby.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0004645 dated January 12, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] Various batteries that can overcome the limitations of current lithium secondary batteries are being researched in terms of battery capacity, safety, output, size, and miniaturization.

[0004] The academic and industrial sectors are continuously conducting research into metal-air batteries, which have a much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries, which are safe and do not pose a risk of explosion, supercapacitors, NaS batteries or RFBs (redox flow batteries), which are large-scale batteries, and thin film batteries, which are ultra-small.

[0005] Among these, all-solid-state batteries are batteries that replace the liquid electrolyte used in existing lithium secondary batteries with a solid, and because they do not use flammable solvents inside the battery, they can significantly improve safety by eliminating the risk of fire or explosion caused by the decomposition reaction of conventional electrolytes.In addition, because lithium metal or lithium alloys can be used as the anode material, they have the advantage of dramatically improving the energy density relative to the mass and volume of the battery.

[0006] In particular, inorganic solid electrolytes for solid-state batteries can be divided into sulfide-based and oxide-based solid electrolytes. Currently, the solid electrolyte that has seen the most technological development is sulfide-based solid electrolytes, and materials have been developed that have ionic conductivity close to that of organic electrolytes.

[0007] Unlike existing lithium secondary batteries that use liquid electrolytes, all-solid-state batteries use a solid electrolyte, which prevents the solid electrolyte from easily penetrating into the pores of the electrode, leading to problems such as physical contact. Research has been conducted to address these issues, including preparing granules containing an active material, creating pores outside the granules, and then injecting a liquid solid electrolyte into the pores and solidifying it. However, this approach has led to additional problems, such as the granules easily detaching from the current collector and the formation of an uneven surface layer due to reduced fluidity of the granules when rolled at high temperatures to form the electrode layer.

[0008] Therefore, the present inventors have studied methods for solving the problem of physical contact between granules containing an active material and a solid electrolyte in the manufacture of electrodes for all-solid-state batteries, and have completed the present invention. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent Publication No. 10-2016-0146737 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides a method for manufacturing an electrode for an all-solid-state battery using secondary granules formed from primary granules by a mechanofusion method in order to improve the performance of the electrode for the all-solid-state battery, and an electrode manufactured thereby. [Means for solving the problem]

[0011] According to a first aspect of the present invention, a method for manufacturing an electrode for an all-solid-state battery is provided, which includes the steps of manufacturing primary particles containing an active material, a conductive material, and a binder, mixing the manufactured primary particles with a solid electrolyte to manufacture secondary particles coated with the solid electrolyte by a mechanofusion method, and applying the manufactured secondary particles onto a current collector to manufacture an electrode.

[0012] According to a specific example of the present invention, the average diameter (D z , 1-y , z , 1-y , c , b , a , 1-y ,

[0016] , y , y , c , 2-z , a , 2-z , b , y , , ) of the particles is 50 μm to 110 μm.

[0013] According to a specific example of the present invention, the average diameter (D 50 ) of the particles is 10 μm to 30 μm.

[0014] According to a specific example of the present invention, the primary particles have a porosity of 55% to 75%. <00,00147>

[0015] According to a specific example of the present invention, the active material is a positive electrode active material, and the positive electrode active material is LiCoO2, LiNiO2, LiMnO2, Li2MnO3, LiMn2O4, Li(Ni a Co b Mn c )O2 (0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1), LiNi 1-y Co y O2 (0 < y < 1), LiCo 1-y Mn y O2 (0 < y < 1), LiNi 1-y Mn y O2 (0 < y < 1), Li(Ni a Co b Mn c )O4 (0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-z Ni z O4 (0 < z < 2), LiMn 2-z Co z O4 (0 < z < 2) and combinations thereof.

[0016] According to one embodiment of the present invention, the solid electrolyte is a sulfide-based solid electrolyte, and the sulfide-based solid electrolyte is selected from the group consisting of Li2S-P2S5, 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, and combinations thereof.

[0017] According to one embodiment of the present invention, the primary granules include 85 wt % to 99.8 wt % of an active material, 0.1 wt % to 10 wt % of a binder, and 0.1 wt % to 10 wt % of a conductive material, based on the total weight of the primary granules.

[0018] According to one embodiment of the present invention, the secondary granules contain 5 wt % to 25 wt % of a solid electrolyte based on the total weight of the secondary granules.

[0019] According to one embodiment of the present invention, the secondary granules have a porosity of 5% to 25%.

[0020] According to one embodiment of the present invention, the secondary granules are coated on the current collector to a thickness of 100 μm to 300 μm.

[0021] According to a second aspect of the present invention, An electrode for an all-solid-state battery is provided, comprising a current collector and a granular layer formed on the current collector.

[0022] According to one embodiment of the present invention, the granular layer is composed of a plurality of granules, and the granules include an active material, a conductive material, and a binder, and are coated with a solid electrolyte.

[0023] According to one embodiment of the present invention, the granules have an average particle diameter (D 50 ) is 10 μm to 30 μm.

[0024] According to one embodiment of the present invention, the solid electrolyte is contained in the granules in an amount of 5 to 25% by weight based on the total weight of the granules. [Effects of the Invention]

[0025] According to a method for manufacturing an electrode for an all-solid-state battery according to an embodiment of the present invention, primary particles having a large average particle size are manufactured, and then the manufactured primary particles are mixed with a solid electrolyte and subjected to a mechanofusion method to manufacture secondary particles having a smaller particle size than the primary particles. As a result, the solid electrolyte can be more densely and uniformly coated on the secondary particles that are actually applied to the current collector.

[0026] This improves the electrical network between the active material and the solid electrolyte, and contributes to improving the performance of the battery when an electrode for an all-solid-state battery manufactured by such a method is applied to the all-solid-state battery. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating a process of forming secondary granules from primary granules according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The embodiments provided by the present invention can all be achieved by the following description. The following description should be understood as describing preferred embodiments of the present invention, and it should be understood that the present invention is not necessarily limited thereto.

[0029] Unless the measurement conditions and methods for the physical properties described herein are specifically described, the physical properties are measured using measurement conditions and methods commonly used by those of ordinary skill in the art.

[0030] One aspect of the present invention is to provide a method for manufacturing an electrode for an all-solid-state battery by coating granules containing an active material on a current collector. According to one embodiment of the present invention, the method for manufacturing an electrode for an all-solid-state battery includes the steps of: preparing primary granules containing an active material, a conductive material, and a binder; mixing the prepared primary granules with a solid electrolyte to prepare secondary granules coated with the solid electrolyte by a mechanofusion method; and coating the prepared secondary granules on a current collector to manufacture an electrode. The primary granules and secondary granules can be distinguished by their preparation process, but they can also be distinguished by physical characteristics such as particle size, which will be described below.

[0031] The active material, conductive material, and binder are agglomerated to prepare primary granules. The primary granules may be prepared by a method commonly used in the relevant technical field and are not particularly limited. For example, the primary granules may be prepared by preparing a slurry and then spray-drying the slurry. The active material, which is a powder of fine particles, is added to a binder solution along with the conductive material to grow the granules to a specific size. According to one embodiment of the present invention, the primary granules are spherical particles containing the active material, conductive material, and binder. The term "spherical" does not strictly mean a perfect sphere, but is generally used as a comprehensive concept that includes particles with a round shape.

[0032] According to one embodiment of the present invention, the primary granules have an average particle diameter (D 50 The average diameter (D 50 The average diameter (D) is the particle diameter (median diameter) at 50% cumulative volume of the particle size distribution, and refers to the particle size at the point where the cumulative value reaches 50% on the cumulative curve obtained by calculating the particle size distribution on a volume basis and setting the total volume to 100%. 50 ) can be measured by laser diffraction. Specifically, the average diameter (D 50The average diameter (D) of such primary granules is 50 μm or more, 55 μm or more, 60 μm or more, 65 μm or more, 70 μm or more, and 110 μm or less, 105 μm or less, 100 μm or less, 95 μm or less, 90 μm or less, or may be 50 μm to 110 μm, 60 μm to 100 μm, or 70 μm to 90 μm. 50 ) was adjusted taking into consideration the particle size of the secondary granules that are subsequently produced by mixing the primary granules with the solid electrolyte and then processing them using the mechanofusion method.

[0033] According to one embodiment of the present invention, the primary granules have a porosity of 55% to 75%. The porosity of the granules refers to the volume ratio of voids in the granules. The porosity can be measured, for example, by Brunauer-Emmett-Teller (BET) measurement or mercury penetration (Hg) porosimetry, but is not limited thereto. Alternatively, the porosity can be calculated using other parameters, such as size, thickness, and density. In all-solid-state batteries, it is important that the granules containing the active material form an electrical network with the solid electrolyte. While the primary granules do not have the final shape when coated on the current collector, the porosity has a significant impact on the morphology of the secondary granules. The higher the porosity of the primary granules, the better the granules can be pulverized. However, because ease of pulverization alone does not have a positive effect on the morphology of the secondary granules, the porosity of the primary granules must be appropriately controlled. Specifically, the porosity of the primary granules is 55% or more, 56% or more, 57% or more, 58% or more, 59% or more, 60% or more, 75% or less, 74% or less, 73% or less, 72% or less, 71% or less, 70% or less, or 55% to 75%, 57% to 72%, 60% to 70%. Within this range, the primary granules can be easily formed into secondary granules of an appropriate shape by the mechanofusion method.

[0034] The electrode for an all-solid-state battery according to an embodiment of the present invention may be either an anode or a cathode, and more specifically, the electrode for an all-solid-state battery is a cathode.

[0035] When the electrode is a negative electrode, the electrode active material contained in the primary particles is not particularly limited as long as it is a material that can be used as a negative electrode active material of a lithium-ion secondary battery. For example, as the negative electrode active material, carbon such as non-graphitizable carbon and graphite-based carbon; Li x Fe2O3(0≦x≦1), Li x WO2(0≦x≦1), Sn x Me 1-x Me' y O z (Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, halogen; 0 < x ≦ 1; 1 ≦ y ≦ 3; 1 ≦ z ≦ 8) and other metal composite oxides; lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; metal oxides such as SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4 and Bi2O5; conductive polymers such as polyacetylene; Li-Co-Ni-based materials; titanium oxides; lithium titanium oxides, etc. One or more species selected from the above can be used. According to a specific example of the present invention, the negative electrode active material can contain a carbon-based material and / or Si.

[0036] When the electrode is a positive electrode, the electrode active material contained in the primary particles is not particularly limited as long as it can be used as a positive electrode active material of a lithium-ion secondary battery. For example, as the positive electrode active material, a lithium transition metal oxide containing one or more transition metals can be used. According to a specific example of the present invention, the positive electrode active material is LiCoO2, LiNiO2, LiMnO2, Li2MnO3, LiMn2O4, Li(Ni a Co b Mn c )O2(0 < a < 1, 0 < b < 1, 0 < c < 1, a + b + c = 1), LiNi 1-y Co y [[ID= 26]]O2(0 < y < 1), LiCo 1-y Mn y O2(0 < y < 1), LiNi 1-y Mn y O2(0 < y < 1), Li(Ni a Co b Mn c)O4(0 < a < 2, 0 < b < 2, 0 < c < 2, a + b + c = 2), LiMn 2-z Ni z O4(0 < z < 2), LiMn 2-z Co z O4(0 < z < 2) and is selected from the group consisting of combinations thereof.

[0037] The conductive material contained in the primary particles is not particularly limited as long as it is a material that can be located within the particles and impart conductivity between the active material and the electrolyte. For example, nickel powder, cobalt oxide, titanium oxide, carbon, etc. can be used as the conductive material. Among the carbon, any one selected from the group consisting of ketjen black, acetylene black, furnace black, graphite, carbon fiber, and fullerene, or one or more thereof can be mentioned.

[0038] The binder contained in the primary particles according to a specific example of the present invention is fine particles in powder form and is mixed with the active material and the conductive material to bond each component and assist in the growth of the particles. Among solid electrolytes, sulfide-based solid electrolytes have moisture-sensitive characteristics such as generating H2S gas when contacting moisture, so it is preferable to exclude moisture to the maximum extent from the time of forming the particles. According to a specific example of the present invention, the binder is an organic binder. The organic binder means a binder dissolved or dispersed in an organic solvent, particularly N-methylpyrrolidone (NMP), and is distinguished from an aqueous binder using water as a solvent or dispersion medium. Specifically, the organic binder can be selected from the group consisting of polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polyimide, polyamideimide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluorine rubber, but is not limited thereto.

[0039] According to one embodiment of the present invention, the active material of the primary granules is 85 wt% to 99.8 wt%, specifically 88 wt% to 99.5 wt%, more specifically 90 wt% to 99.3 wt%, the binder is 0.1 wt% to 10 wt%, specifically 0.2 wt% to 8 wt%, more specifically 0.3 wt% to 7 wt%, and the conductive material is 0.1 wt% to 10 wt%, specifically 0.2 wt% to 8 wt%, more specifically 0.3 wt% to 7 wt%. When the contents of the active material, binder, and conductive material are adjusted within the above ranges, battery performance is advantageously improved.

[0040] The produced primary granules are mixed with a solid electrolyte and then mechanofusion is used to produce secondary granules coated with the solid electrolyte. Figure 1 shows the process of forming secondary granules from the primary granules. As shown in Figure 1, the structure of the primary granules 10 is broken down by the mechanofusion method, and the broken primary granules 10 are coated with a solid electrolyte 20 to form secondary granules 2.

[0041] The solid electrolyte may be coated on at least a part or all of the surface of the disintegrated primary granules. The solid electrolyte may be one or more selected from polymer-based solid electrolytes, sulfide-based solid electrolytes, and oxide-based solid electrolytes. The polymer-based solid electrolyte may be a polymer solid electrolyte formed by adding a polymer resin to a solvated lithium salt, or a polymer gel electrolyte formed by adding an organic electrolyte solution containing an organic solvent and a lithium salt, an ionic liquid, a monomer or an oligomer, etc., to a polymer resin. According to one embodiment of the present invention, the lithium salt is an ionizable lithium salt, such as Li + X - The anion of such a lithium salt is not particularly limited, but may be F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 -, (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - 、 CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - , (CF3CF2SO2)2N - Examples include:

[0042] According to one embodiment of the present invention, the solid electrolyte is a sulfide-based solid electrolyte, which contains sulfur (S) and has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and may include Li-PS-based glass or Li-PS-based glass ceramics. Non-limiting examples of such sulfide-based solid electrolytes include Li2S-P2S5, 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, and the like, and one or more of these may be included.

[0043] The solid electrolyte can be coated onto granules containing an active material using various methods commonly used in the art, including a coating method that can form mechanochemical bonding to increase the bonding strength between the solid electrolyte coating layer and the granules. According to one embodiment of the present invention, the solid electrolyte can be coated onto the granules using a mechanofusion method that can apply high shear force during coating. While the mechanofusion method essentially applies high shear force to the granules, it can cause deformation or collapse of the granules depending on their physical properties. The primary granules according to one embodiment of the present invention are larger in particle size and have larger voids than the secondary granules that are actually coated on the current collector, making their structure more susceptible to collapse during the mechanofusion method. According to one embodiment of the present invention, the mechanofusion method can be performed at a rotational speed of 1,000 rpm to 5,000 rpm for 5 to 20 minutes. Specifically, the rotation speed may be 1000 rpm to 5000 rpm, 1500 rpm to 4500 rpm, 2000 rpm to 4000 rpm, or 2500 rpm to 3500 rpm, and the rotation time may be 5 minutes to 20 minutes, 8 minutes to 17 minutes, or 10 minutes to 15 minutes. Within these ranges, secondary granules of appropriate size, in which the solid electrolyte is densely coated on the granules, can be formed.

[0044] According to one embodiment of the present invention, the secondary granules have an average particle diameter (D 50 The average diameter (D) of the secondary granules is 10 μm to 30 μm. 50 ) is measured in the same manner as for the primary granules. Specifically, the average diameter (D 50) is 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, or 16 μm or more, or 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, or 24 μm or less, and may be 10 μm to 30 μm, 13 μm to 27 μm, or 16 μm to 24 μm. Within this average diameter range, the secondary granules can more easily form an electrical network between the solid electrolyte and the active material, and a certain level of voids can be introduced between the granules when stacked on a current collector, making it easy to introduce additional solid electrolyte.

[0045] According to one embodiment of the present invention, the secondary granules have a porosity of 5% to 25%. The porosity of the secondary granules is measured in the same manner as the primary granules. Specifically, the porosity of the secondary granules is 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, or 10% or more, and 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, or 20% or less, and 5% to 25%, 7% to 22%, or 10% to 20%. The secondary granules are formed by the disintegration of primary granules and are coated with a solid electrolyte, so they have a lower porosity than the primary granules. Within this porosity range, the secondary granules can form an appropriate level of electrical network between the solid electrolyte and the active material.

[0046] According to one embodiment of the present invention, the secondary granules contain 5 wt % to 25 wt % of solid electrolyte, based on the total weight of the secondary granules. Specifically, the solid electrolyte content is 5 wt % or more, 6 wt % or more, 7 wt % or more, 8 wt % or more, 9 wt % or more, or 10 wt % or more, and 25 wt % or less, 24 wt % or less, 23 wt % or less, 22 wt % or less, 21 wt % or less, or 20 wt % or less, or may be 5 wt % to 25 wt %, 7 wt % to 22 wt %, or 10 wt % to 20 wt %. It is preferable that the solid electrolyte content in the secondary granules be appropriately adjusted in relation to the active material of the solid electrolyte. If the solid electrolyte content is too high, the active material content may be undesirably low, while if the solid electrolyte content is too low, the electrical network between the solid electrolyte and the active material may be poorly formed. When a solid electrolyte is coated using the mechanofusion method according to one embodiment of the present invention, the content of the solid electrolyte may be high because the solid electrolyte can be sufficiently supplied between the voids of the granules, but the content of the solid electrolyte may be reduced because the solid electrolyte can be uniformly coated on the entire surface of the granules.

[0047] An electrode for an all-solid-state battery according to one embodiment of the present invention is fabricated by loading fabricated secondary granules onto a current collector to form a sheet-shaped granule layer. The current collector may be an electrically conductive material such as a metal sheet, and an electrode known in the art may be used depending on the polarity of the battery. Because the secondary granules constituting the granule layer are individually coated with a solid electrolyte, a sufficient electrical network can be formed between the granules constituting the granule layer. However, the electrical network can be supplemented by impregnating the voids between the granule layers with a solid electrolyte and drying it. Furthermore, using the same type of solid electrolyte as the coating layer for the supplemented solid electrolyte can reduce resistance within the battery and contribute to improved battery performance.

[0048] According to one embodiment of the present invention, the secondary granules are coated on the current collector to a thickness of 100 μm to 300 μm. In other words, the electrode active material layer in the electrode for the all-solid-state battery has a thickness of 100 μm to 300 μm. Here, the electrode active material layer refers to a sheet-shaped layer coated on the current collector, excluding the current collector if a current collector is used in manufacturing the electrode, and the electrode active material layer includes the above-mentioned granules and a solid electrolyte that is filled in the gaps between the granules as needed. Specifically, the thickness of the electrode active material layer may be 100 μm or more, 110 μm or more, 120 μm or more, 130 μm or more, 140 μm or more, or 150 μm or more, or 300 μm or less, 290 μm or less, 280 μm or less, 270 μm or less, 260 μm or less, or 250 μm or less, such as 100 μm to 300 μm, 120 μm to 270 μm, or 150 μm to 250 μm. If the thickness of the electrode active material layer is less than this range, the loading amount of the active material may be reduced, and the improvement in battery performance may not be significant. If the thickness of the electrode active material layer is greater than this range, the durability of the electrode may be reduced, and the improvement in battery performance may not be significant.

[0049] According to one embodiment of the present invention, the porosity of the granule layer formed by coating the secondary granules on the current collector is 30% to 60%. Here, the granule layer refers to the region formed by the granules coated on the current collector, and is the same layer as the electrode active material layer in which no additional solid electrolyte is introduced other than the secondary granules. The porosity of the granule layer is measured in the same manner as for the primary granules or secondary granules. Specifically, the porosity of the granule layer is 30% or more, 31% or more, 32% or more, 33% or more, 34% or more, or 35% or more, and 60% or less, 59% or less, 58% or less, 57% or less, 56% or less, or 55% or less, and may be 30% to 60%, 32% to 57%, or 35% to 55%. If necessary, additional solid electrolyte may be introduced into the pores of the granule layer.

[0050] In one aspect of the present invention, an all-solid-state battery is provided that includes the above-described all-solid-state battery electrode as a cathode and / or anode. In constructing the all-solid-state battery, a separate solid electrolyte layer may be disposed between the cathode and anode in addition to the solid electrolyte contained in the electrodes. This solid electrolyte layer may also function as a separator in a typical lithium secondary battery. The above-described electrodes may be used together with a liquid electrolyte to form a semi-solid-state battery, in which case a separate polymer separator may be required.

[0051] The polymer separator is interposed between the anode and the cathode and serves to electrically insulate the anode and the cathode while allowing lithium ions to pass through. The polymer separator may be any polymer insulating film commonly used in the field of all-solid-state batteries, and is not particularly limited.

[0052] In one aspect of the present invention, there are provided a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0053] Specific examples of the device include, but are not limited to, power tools powered by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and energy storage systems.

[0054] Preferred examples are presented below to aid in understanding the present invention. However, the following examples are provided merely to facilitate understanding of the present invention, and the present invention is not limited thereto.

[0055] Example Example 1 LiNi as the active material 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), carbon black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were mixed in N-methylpyrrolidone solvent at a weight ratio of 94:3:3 (active material: conductive material: binder) to prepare a slurry, which was then spray-dried to produce a powder with an average diameter (D 50 ) primary granules (porosity: approximately 65%) were produced.

[0056] The sulfide-based solid electrolyte Li2S-P2S5 was used together with the primary granules in a mechanofusion device (manufacturer: Hosokawa Micron, product: Nobilta NOB-130) at 3,000 rpm for 10 minutes to produce a granule with an average diameter of approximately 20 μm and a coating of approximately 15 wt% sulfide-based solid electrolyte (D 50 ) secondary granules (porosity: approximately 16%) were produced.

[0057] Here, the average diameter (D 50 The particle size was measured using a particle analyzer (manufacturer: Malvern, product name: Mastersizer), and the porosity was measured using a mercury porosity analyzer (manufacturer: Micromeritics, product name: Autopore).

[0058] The secondary granules were applied to an aluminum current collector of approximately 100 μm in thickness and then rolled to prepare a cathode of approximately 300 μm in thickness. The granule layer in the cathode had a porosity of approximately 45%.

[0059] Furthermore, Li2S-LiCl-P2S5 was mixed with a polyvinylidene fluoride (PVDF) solution (a solution of PVDF and toluene mixed in a weight ratio of 8:92) to prepare a slurry, which was then dried to prepare a solid electrolyte membrane approximately 50 μm thick. Lithium foil approximately 100 μm thick was used as the anode. The cathode, solid electrolyte membrane, and anode were stacked and compressed to prepare an electrode assembly, which was then placed inside a battery case to prepare an all-solid-state battery.

[0060] Comparative Example 1 Average diameter (D 50 An all-solid-state battery was manufactured in the same manner as in Example 1, except that primary granules having a particle size of about 150 μm were prepared and used.

[0061] Comparative Example 2 During the production of the positive electrode, the average diameter (D 50 An all-solid-state battery was manufactured in the same manner as in Example 1, except that primary granules having a particle size of about 20 μm were prepared and used.

[0062] Comparative Example 3 An all-solid-state battery was manufactured in the same manner as in Example 1, except that a simple mechanical mixing device (manufacturer: Red Devil, product: Classic Shaker 1400, conditions: 60 Hz, 60 minutes) was used instead of the mechanofusion device when manufacturing the positive electrode.

[0063] The average diameter (D 50 ) are as shown in Table 1 below.

[0064] [Table 1]

[0065] Experimental example: Performance evaluation of manufactured batteries The all-solid-state batteries prepared in Example 1 and Comparative Examples 1 to 3 were charged / discharged, and the discharge capacity (mAh / g) and coulombic efficiency (%) in the first cycle were measured, and the results are shown in Table 2. When evaluating the battery performance, charge / discharge was performed at a temperature of 60°C under the following conditions.

[0066] Charging conditions: 0.05C, 4.25V CC / CV, 0.01C cut-off Discharge conditions: 0.05C, 3V

[0067] [Table 2]

[0068] According to Table 2, in Example 1, the primary particles were crushed into appropriate-sized secondary particles by the strong shear force of the mechanofusion method, and the solid electrolyte was thinly and uniformly coated on the surfaces of the crushed secondary particles, resulting in the all-solid-state battery of Example 1 exhibiting high discharge capacity and coulombic efficiency.

[0069] In contrast, in Comparative Example 1, the primary particles were large and were broken into relatively large secondary particles even when strong shear force was applied using the mechanofusion method. As a result, the solid electrolyte was coated only on the surfaces of the large secondary particles, preventing the active material inside the particles from easily contacting the solid electrolyte. As a result, the all-solid-state battery of Comparative Example 1 did not exhibit the same high discharge capacity and coulombic efficiency as Example 1.

[0070] In Comparative Example 2, the size of the primary particles containing the active material, conductive material, and binder was too small, so when a strong shear force was applied according to the mechanofusion method, the conductive material and binder separated and became coated with the solid electrolyte. This could act as resistance when using the active material, so the all-solid-state battery of Comparative Example 2 did not exhibit the same high discharge capacity and coulombic efficiency as Example 1.

[0071] In Comparative Example 3, similar to Example 1, secondary particles of appropriate size could be formed using the mechanical mixing method, but detailed analysis of the particle surfaces revealed that the solid electrolyte was not uniformly coated thinly on the surfaces of the secondary particles, but rather aggregated unevenly to form islands. As a result, the active material and the solid electrolyte did not make proper electrical contact, and the all-solid-state battery of Comparative Example 3 did not exhibit as high a discharge capacity and coulombic efficiency as Example 1.

[0072] Any simple modifications or variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be defined by the appended claims. [Explanation of symbols]

[0073] 1:1st granule 2: Secondary granules 10: Disintegrated primary granules (including active material, conductive material, and binder) 20: Solid electrolyte

Claims

1. (1) preparing primary granules containing an active material, a conductive material, and a binder; (2) mixing the prepared primary granules with a solid electrolyte to prepare secondary granules coated with the solid electrolyte by a mechanofusion method; and (3) applying the produced secondary granules onto a current collector to produce an electrode; The primary granules have an average particle diameter (D ５０ ) is 50 μm to 110 μm, The primary granules have a porosity of 55% to 75%; The secondary granules have an average particle diameter (D 50 ) of 10 μm to 30 μm, The method for manufacturing an electrode for an all-solid-state battery, wherein the secondary granules have a porosity of 5% to 25%.

2. the active material is a positive electrode active material, The positive electrode active material is LiCoO ２ , LiNiO ２ , LiMnO ２ , Li ２ MnO ３ , LiMn ２ O ４ , Li(Ni ａ Co ｂ Mn ｃ ) O ２ (0<a<1, 0<b<1, 0<c<1, a+b+c=1), LiNi １－ｙ Co ｙ O ２ (0<y<1), LiCo １－ｙ Mn ｙ O ２ (0<y<1), LiNi １－ｙ Mn ｙ O ２ (0<y<1), Li(Ni ａ Co ｂ Mn ｃ ) O ４ (0<a<2, 0<b<2, 0<c<2, a+b+c=2), LiMn ２－ｚ Ni ｚ O ４ (0<z<2), LiMn ２－ｚ Co ｚ O ４ 2. The method for producing an electrode for an all-solid-state battery according to claim 1, wherein z is selected from the group consisting of (0<z<2) and combinations thereof.

3. the solid electrolyte is a sulfide-based solid electrolyte, The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ , Li ２ S-LiI-P ２ S ５ , Li ２ S-LiI-Li ２ O-P ２ S ５ , Li ２ S-LiBr-P ２ S ５ , Li ２ S-LiCl-P ２ S ５ , Li ２ S-Li ２ O-P ２ S ５ , Li ２ S-Li ３ P.O. ４ -P ２ S ５ , Li ２ S-P ２ S ５ -P ２ O ５ , Li ２ S-P ２ S ５ -SiS ２ , Li ２ S-P ２ S ５ - SnS, Li ２ S-P ２ S ５ -Al ２ S ３ , Li ２ S-GeS ２ , Li ２ S-GeS ２ 2. The method for producing an electrode for an all-solid-state battery according to claim 1, wherein the metal oxide is selected from the group consisting of ZnS, ZnS, and combinations thereof.

4. 2. The method of claim 1, wherein the primary granules contain 85 wt % to 99.8 wt % of an active material, 0.1 wt % to 10 wt % of a binder, and 0.1 wt % to 10 wt % of a conductive material, based on a total weight of the primary granules.

5. 2. The method of claim 1, wherein the secondary granules contain 5 to 25 wt % of the solid electrolyte based on the total weight of the secondary granules.

6. The method of claim 1 , wherein the secondary granules are applied to a current collector to a thickness of 100 μm to 300 μm.

7. An electrode for an all-solid-state battery comprising a current collector and a granular layer formed on the current collector, The granular layer is composed of a plurality of granules, The granules contain an active material, a conductive material, and a binder, and are coated with a solid electrolyte; The granules have an average particle diameter (D ５０ ) is 10 μm to 30 μm, The solid electrolyte is contained in the granules in an amount of 5 to 25% by weight based on the total weight of the granules, The granules have a porosity of 5% to 25%.

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