Electrode for all-solid-state battery

Abstract

An electrode for an all-solid-state battery is provided, comprising granules coated with a sulfide-based solid electrolyte. The granules include an active material, a conductive material, and a binder, and the conductive material is a carbon nanotube having a diameter of 1 nm to 10 nm. The carbon nanotube has a diameter of 400 mm or less. 2 / g~1000m 2 When the electrode for an all-solid-state battery is applied to an all-solid-state battery, the performance of the battery can be improved.

Description

[Technical field]

[0001] The present invention relates to an electrode for an all-solid-state battery, in particular an electrode for an all-solid-state battery comprising granules coated with a sulfide-based solid electrolyte.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2021-0115690 filed on August 31, 2021, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference. [Background technology]

[0003] Currently, various batteries capable of overcoming the limitations of lithium secondary batteries are being researched from the standpoints of battery capacity, safety, output, size increase, and miniaturization.

[0004] Representatively, metal-air batteries, which have a much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries, which are safe and have no risk of explosion, supercapacitors, which have higher output, NaS batteries or RFBs (redox flow batteries), and thin film batteries, which are small in size, are being continuously researched in both academia and industry.

[0005] Among these, all-solid-state batteries refer to batteries in which the liquid electrolyte used in existing lithium secondary batteries has been replaced with a solid, and they can significantly improve safety by not using flammable solvents in the battery and by eliminating the risk of fire or explosion caused by the decomposition reaction of conventional electrolytes. In addition, they have the advantage of being able to dramatically improve the energy density relative to the mass and volume of the battery, as Li metal or Li alloy can be used as the anode material.

[0006] In particular, inorganic solid electrolytes in solid-state batteries are divided into sulfide-based and oxide-based solid electrolytes. Currently, the solid electrolyte that has undergone the most technological development is the sulfide-based solid electrolyte, and the ionic conductivity of this solid electrolyte has been developed to a level close to that of organic electrolytes.

[0007] Sulfide-based solid electrolytes are 10% of all solid electrolytes. -3 ~10 -2 It has a high ionic conductivity of S / cm, is ductile, and has good contact with the interface, which is advantageous for improving resistance, but it is necessary to create an extremely dry environment during production due to its moisture sensitivity, such as generating H2S gas when in contact with water. In addition, it is necessary to improve the cohesion between the active material and the solid electrolyte, and a high-density electrode is required by reducing the porosity.

[0008] Therefore, in order to solve the problems faced in the art, the present inventors have continuously studied electrodes for solid-state batteries and 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 an electrode for an all-solid-state battery, which includes granules coated with a sulfide-based solid electrolyte, and which can improve the performance of the battery when used as an electrode for an all-solid-state battery. [Means for solving the problem]

[0011] According to a first aspect of the present invention, The present invention provides an electrode for all-solid-state battery including particles coated with a sulfide-based solid electrolyte, wherein the particles contain an active material, a conductive material, and a binder, and the conductive material is a carbon nanotube having a diameter of 1 nm to 10 nm.

[0012] In one specific example of the present invention, the carbon nanotube has a BET specific surface area of 400 m 2 / g to 1000 m 2 / g.

[0013] In one specific example of the present invention, the carbon nanotube is a single-walled carbon nanotube.

[0014] In one specific example of the present invention, the particles are spherical particles having a diameter of 30 μm to 150 μm.

[0015] In one specific example of the present invention, the particles have a porosity of 10% to 40%.

[0016] In one specific example of the present invention, the electrode for all-solid-state battery is a positive electrode, and the 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, 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.

[0017] In one embodiment of the present invention, the binder is an organic binder, and the organic binder is 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, polyamide-imide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butylene rubber, and fluororubber.

[0018] In one embodiment of the present invention, the granules contain 85% to 99.8% by weight of active material, 0.1% to 10% by weight of binder, and 0.1% to 10% by weight of conductive material.

[0019] In one embodiment of the present invention, when the granule is separated into a first region, a second region, and a third region from the center of the granule to the outside of the granule at equal intervals across the inner diameter of the granule, the conductive material content in the granule increases in the order of the first region, the second region, and the third region.

[0020] In one embodiment of the present invention, the third region of the granule is 40 wt % or more based on the total content of the conductive material in the granule.

[0021] In one embodiment of the present invention, the electrode active material layer including granules coated with a sulfide-based solid electrolyte in the all-solid-state battery electrode has a thickness of 100 μm to 300 μm.

[0022] In one embodiment of the present invention, the electrode active material layer including granules coated with a sulfide-based solid electrolyte in the all-solid-state battery electrode includes 20 wt % to 40 wt % of the sulfide-based solid electrolyte based on the content of the granules.

[0023] According to a second aspect of the present invention, The present invention provides an all-solid-state battery including the above-mentioned all-solid-state battery electrode as a positive electrode or a negative electrode. Effect of the Invention

[0024] In an electrode for an all-solid-state battery including granules coated with a sulfide-based solid electrolyte, the granules include an active material, a conductive material, and a binder. By selecting the conductive material included in the granules as carbon nanotubes having a diameter of 1 nm to 10 nm, the interaction between the active material included in the granules and the sulfide-based solid electrolyte coated on the granules is improved, and the performance of the battery can be improved when the electrode for an all-solid-state battery is applied to the all-solid-state battery. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 is a diagram showing the shape of a granule according to one embodiment of the present invention. [Diagram 2] 1 is a scanning electron microscope (SEM) image of the granules prepared according to Example 1 of the present invention, the magnification of which is ×1,000. [Diagram 3] 1 is a scanning electron microscope (SEM) image of the granules prepared according to Example 1 of the present invention, the magnification of the image is ×10,000. [Figure 4] 1 is a scanning electron microscope (SEM) image of the granules prepared according to Comparative Example 1 of the present invention, the magnification of which is ×2,000. [Diagram 5] 1 is a scanning electron microscope (SEM) image of the granules prepared according to Comparative Example 1 of the present invention, the magnification of the image is ×500. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] All of the embodiments provided by the present invention can be achieved by the following description. It should be understood that the following description describes preferred embodiments of the present invention, and that the present invention is not necessarily limited thereto.

[0027] Unless the measurement conditions and methods are specifically described for the physical properties described in this specification, the physical properties are measured according to the measurement conditions and methods commonly used by those of ordinary skill in the art.

[0028] In one aspect of the present invention, an electrode for an all-solid-state battery is provided, which includes granules coated with a sulfide-based solid electrolyte. The granules are spherical particles including an active material, a conductive material, and a binder. Here, the term "spherical" does not mean a perfect sphere in the strict sense, but is used as a general concept including particles of a round shape. The fine particles of the active material in a powder state are bound together with the conductive material by a binder solution to grow into particles having a specific range of specifications.

[0029] According to one embodiment of the present invention, the granules are spherical particles having a diameter of 30 μm to 150 μm. Here, the spherical particles do not mean perfectly spherical particles, so the diameter means the largest value among the distances from any one point on the particle surface to another point on the surface. Specifically, the diameter of the granules may be 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, or 150 μm or less, 145 μm or less, 140 μm or less, 135 μm or less, 130 μm or less, 125 μm or less, or 120 μm or less. If the diameter of the granules is less than the above range, the voids in the granule layer are small, and the amount of the sulfide-based solid electrolyte that penetrates between the granules and coats them is reduced, so that the improvement in battery performance may not be evident. If the diameter of the granules is more than the above range, the distance between the surface in contact with the sulfide-based solid electrolyte and the center of the granule becomes large, so that the improvement in battery performance may not be evident.

[0030] The electrode for an all-solid-state battery according to one embodiment of the present invention may be either a negative electrode or a positive electrode, and more specifically, the electrode for an all-solid-state battery may be a positive electrode.

[0031] When the electrode is a negative electrode, any electrode active material contained in the granules can be used as long as it is a material that can be used as a negative electrode active material for a lithium ion secondary battery. For example, the negative electrode active material may be carbon such as non-graphitizable carbon or 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 and the like, and one or more species selected therefrom can be used. According to one specific example of the present invention, the negative electrode active material may contain a carbon-based material and / or Si.

[0032] When the electrode is a positive electrode, any electrode active material contained in the granules can be used without limitation as long as it can be used as a positive electrode active material for a lithium ion secondary battery. For example, the positive electrode active material may be a lithium transition metal oxide containing one or more transition metals. In one 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 O2(0 < y < 1), LiCo 1-y Mn y O2, 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 04(0 < z < 2), LiMn 2-z Co z It is selected from the group consisting of O4(0 < z < 2) and combinations thereof.

[0033] The conductive material contained in the particles according to a specific example of the present invention is a carbon nanotube having a diameter of 1 nm to 10 nm. Here, the diameter means the largest value among the distances from any one outermost point based on the circular cross-section of the carbon nanotube to another point. Specifically, the diameter of the carbon nanotube may be 1 nm or more, 2 nm or more, 3 nm or more, and may be 10 nm or less, 9 nm or less, 8 nm or less. When the diameter of the carbon nanotube is less than the above range, the external area of the carbon nanotube is small, and it is difficult to form an effective structure among the active materials, such as a reduction in the area in contact with the active material, and the improvement of the battery performance may not be clearly manifested. When the diameter of the carbon nanotube exceeds the above range, it is difficult to finely connect the active materials, and a large amount of active materials cannot be systematically covered compared to the input weight of the carbon nanotube, and the improvement of the battery performance may not be clearly manifested.

[0034] According to a specific example of the present invention, the carbon nanotube has a BET specific surface area of 400 m 2 / g to 1000 m 2 / g. The BET specific surface area is the specific surface area measured by the BET method. Specifically, it is preferably calculated by obtaining the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-miniII of BEL Japan. Specifically, the BET specific surface area of the carbon nanotube may be 400 m 2 / g or more, 450 m 2 / g or more, 500 m 2 / g or more, and may be 1000 m 2 / g or less, 950 m 2 / g or less, 900 m 2 / g or less, 850 m 2 / g or less, 800 m2 / g or less, 750m 2 / g or less, 700m 2 If the BET specific surface area of ​​the carbon nanotube is less than the above range, the area in contact with the active material is reduced relative to the weight of the carbon nanotube, and the improvement in battery performance may not be evident, whereas if the BET specific surface area of ​​the carbon nanotube is more than the above range, the carbon nanotube cannot easily come into contact with the active material or solid electrolyte, and the improvement in battery performance may not be evident.

[0035] According to one embodiment of the present invention, the carbon nanotube is a single-walled carbon nanotube. The single-walled carbon nanotube has a structure that is advantageous for contacting with an active material even with a small weight compared to the multi-walled carbon nanotube, and is therefore advantageous for improving the performance of a battery. The carbon nanotube may have a single molecular fiber structure.

[0036] The binder contained in the granule according to one embodiment of the present invention is mixed with the active material and the conductive material, which are fine particles in a powder state, to bind the components and promote particle growth. Since the sulfide-based solid electrolyte has a moisture-sensitive property, such as generating H2S gas when in contact with moisture, it is preferable to remove moisture as much as possible from the time of forming the granule. According to one embodiment of the present invention, the binder is an organic binder. The organic binder refers to a binder that dissolves or disperses in an organic solvent, particularly N-methylpyrrolidone (NMP), and is distinguished from an aqueous binder that uses water as a solvent or dispersion medium. Specifically, the organic binder may 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, polyamide-imide, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butylene rubber, and fluororubber, but is not limited thereto.

[0037] According to one embodiment of the present invention, the granules contain 85% to 99.8% by weight of active material, specifically 88% to 99.5% by weight, more specifically 90% to 99.3% by weight of binder, 0.1% to 10% by weight, specifically 0.2% to 8% by weight, more specifically 0.3% to 7% by weight of conductive material, and 0.1% to 10% by weight, specifically 0.2% to 8% by weight, more specifically 0.3% to 7% by weight of conductive material. When the contents of the active material, binder, and conductive material are adjusted within the above ranges, it may be advantageous to improve the performance of the battery.

[0038] According to one embodiment of the present invention, the granules have a porosity of 10% to 40%. The porosity of the granules means a volume ratio of voids in the granules, and the porosity may be measured by, for example, a Brunauer-Emmett-Teller (BET) measurement method or a mercury penetration method (Hg porosimeter), but is not limited thereto. Specifically, the porosity of the granules may be 10% or more, 15% or more, 20% or more, or 25% or more, or 40% or less, 35% or less, or 30% or less. If the porosity of the granules is less than the above range, the sulfide-based solid electrolyte may not be in close contact with the granules, and the improvement in battery performance may not be evident. If the porosity of the granules is more than the above range, the amount of active material is reduced compared to the volume of the granules, and it is difficult to provide an electrode with a high loading of active material, and therefore the improvement in battery performance may not be evident.

[0039] When manufacturing granules, a binder solution is added along with the fine particles of active material and conductive material in powder form to grow the particle size of the granules to a specific level, and the inside of the device can rotate to make the granules spherical and separate each granule. This rotation causes centrifugal force to act on the granules, and the components of the granules can be more densely concentrated on the outside of the granules than in the center of the granules. In particular, the carbon nanotubes, which are conductive materials, are more susceptible to the centrifugal force due to their structure and other characteristics.

[0040] When preparing granules, a binder solution is added along with the fine particles of active material and conductive material in powder form to grow the particle size of the granules to a specific level. As the solvent dries from the formed granules, the binder and conductive material, which are relatively light in weight, are positioned outside the granules, and the density of the outside of the granules may increase. In particular, the aforementioned carbon nanotubes, which are conductive materials, are small and light in size and may be positioned in greater numbers at the outside of the granules after drying.

[0041] FIG. 1 is a diagram showing the shape of a granule according to an embodiment of the present invention. As shown in FIG. 1, the inside of the granule can be separated into a first region (region A), a second region (region B), and a third region (region C). The first region, the second region, and the third region are separated by dividing the inside diameter of the granule at equal intervals, and the first region is located at the center of the granule, the third region is located at the outermost part of the granule, and the second region is located between the first region and the third region. According to an embodiment of the present invention, the content of the conductive material in the granule increases in the order of the first region, the second region, and the third region. According to an embodiment of the present invention, the third region of the granule is 40% by weight or more, specifically 50% by weight or more, more specifically 60% by weight or more, based on the total content of the conductive material in the granule. Due to the structural characteristics of the carbon nanotubes described above, even if the conductive material has a higher content distribution outside the granule than in the center, it can still function sufficiently as a path for electrons to move between the sulfide-based solid electrolyte and the active material.

[0042] In the electrode for the all-solid-state battery, the solid electrolyte is coated on at least a part or the whole of the surface of the granule. The solid electrolyte may be a polymer solid electrolyte formed by adding a polymer resin to a lithium salt in which the polymer solid electrolyte is solvated, or may be a polymer gel electrolyte in which an organic electrolyte containing an organic solvent and a lithium salt, an ionic liquid, a monomer or an oligomer, etc. is contained in a polymer resin. The solid electrolyte may be one or more selected from a polymer solid electrolyte, a sulfide solid electrolyte, and an oxide solid electrolyte, and according to one embodiment of the present invention, the solid electrolyte is a sulfide solid electrolyte. In the electrode for the all-solid-state battery, the sulfide solid electrolyte is applied by impregnating a granule layer made of the granules described above in a sulfide electrolyte and then drying.

[0043] According to one embodiment of the present invention, the lithium salt is Li as an ionizable lithium salt. + 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 - In one embodiment of the present invention, the sulfide-based solid electrolyte contains sulfur (S) and has ion 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 ceramic. 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 may include one or more of these.

[0044] The electrode for an all-solid-state battery according to an embodiment of the present invention may be prepared by loading granules onto a current collector to prepare a granular layer in the form of a sheet, impregnating the granular layer with a sulfide-based electrolyte, and drying the same. In this case, the current collector is an electrically conductive material such as a metal plate, and an electrode known in the art may be appropriately used depending on the polarity of the battery.

[0045] According to one embodiment of the present invention, the electrode active material layer including the granules coated with the sulfide-based solid electrolyte in the all-solid-state battery electrode has a thickness of 100 μm to 300 μm. Here, the electrode active material layer means a layer in the form of a sheet applied on the current collector excluding the current collector when the current collector is used in the manufacture of the electrode. 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, 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. If the thickness of the electrode active material layer is less than the above range, the loading amount of the active material may decrease, and the improvement in the performance of the battery may not be clearly observed, and if the thickness of the electrode active material layer exceeds the above range, the durability of the electrode may decrease, and the improvement in the performance of the battery may not be clearly observed.

[0046] According to one embodiment of the present invention, the electrode active material layer including the granules coated with the sulfide-based solid electrolyte in the all-solid-state battery electrode includes 20% by weight to 40% by weight of the sulfide-based solid electrolyte based on the content of the granules. Specifically, the content of the sulfide-based solid electrolyte may be 20% by weight or more, 21% by weight or more, 22% by weight or more, 23% by weight or more, 24% by weight or more, or 25% by weight or more, or 40% by weight or less, 39% by weight or less, 38% by weight or less, 37% by weight or less, 36% by weight or less, or 35% by weight or less. If the content of the sulfide-based solid electrolyte is less than the above range, the electron transfer between the electrolyte and the active material in the all-solid-state battery is not easy, and the improvement in the battery performance may not be clearly observed. If the content of the sulfide-based solid electrolyte is more than the above range, the loading amount of the active material is relatively reduced, and the improvement in the battery performance may not be clearly observed.

[0047] 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 positive electrode and / or a negative electrode. In constructing the all-solid-state battery, a separate solid electrolyte layer may be introduced between the positive electrode and the negative electrode in addition to the solid electrolyte contained in the electrode, and such a solid electrolyte layer may also function as a separator in a general lithium secondary battery. The above-described electrode may be used as a semi-solid-state battery by using a liquid electrolyte together, in which case a separate polymer separator may be further required.

[0048] The polymer separator is interposed between the negative electrode and the positive electrode, and serves to electrically insulate the negative electrode from the positive electrode and to allow lithium ions to pass through. The polymer separator may be any polymer separator membrane used in the field of general all-solid-state batteries, and is not particularly limited.

[0049] In one aspect of the present invention, there is 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.

[0050] 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), plug-in hybrid electric vehicles (PHEVs), and the like; electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; and power storage systems.

[0051] Preferred examples are presented below to aid in understanding the present invention. However, the following examples are provided only to facilitate understanding of the present invention, and the present invention is not limited thereto.

[0052] Manufacturing example: Manufacturing granules containing active materials Manufacturing Example 1 LiNi as active material 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), linear single-walled carbon nanotubes (diameter: approx. 5 nm, BET specific surface area: approx. 600 m 2 The active material was mixed with polyvinylidene fluoride (PVDF) as a binder in a weight ratio of 94:3:3 (active material: conductive material: binder) in N-methylpyrrolidone solvent to prepare a slurry, which was then spray-dried to produce granules with a diameter of approximately 60 μm (porosity: 30%).

[0053] Comparative Manufacturing Example 1 LiNi as active material 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), spherical carbon black (diameter: approx. 20 nm, BET specific surface area: approx. 200 m 2 The active material was mixed with water (H20) in a weight ratio of 94:3:3 (active material:conductive material:binder) to prepare a slurry, which was then spray-dried to prepare granules with a diameter of approximately 60 μm (porosity: 20%).

[0054] Comparative Manufacturing Example 2 LiNi as active material 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), and linear multi-walled carbon nanotubes (diameter: approx. 13 nm, BET specific surface area: approx. 200 m 2 The active material was mixed with polyvinylidene fluoride (PVDF) as a binder in a weight ratio of 94:3:3 (active material: conductive material: binder) in N-methylpyrrolidone solvent to prepare a slurry, which was then spray-dried to produce granules with a diameter of approximately 60 μm (porosity: 23%).

[0055] Example: Manufacture of a battery containing the produced granules Example 1 The granules prepared in Preparation Example 1 were applied to one side of an aluminum current collector, rolled, impregnated with a sulfide-based electrolyte of Li2S-P2S5, dried and rolled to prepare a positive electrode with a thickness of about 200 μm (sulfide-based electrolyte was about 30% by weight of the granules). Li2S-LiCl-P2S5 was mixed with a polyvinylidene fluoride (PVDF) solution (a solution in which PVDF and toluene were mixed in a weight ratio of 8:92) to prepare a slurry, which was then applied to a thickness of about 50 μm on a lithium foil (Li foil) with a thickness of about 150 μm to prepare a solid electrolyte and a negative electrode including the same. The positive and negative electrodes were stacked and pressed to prepare an electrode assembly, which was then placed inside a battery case to prepare an all-solid-state battery.

[0056] Comparative Example 1 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the granules prepared in Comparative Preparation Example 1 were used instead of Preparation Example 1 when preparing the positive electrode.

[0057] Comparative Example 2 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the granules prepared in Comparative Preparation Example 2 were used instead of Preparation Example 1 when preparing the positive electrode.

[0058] Comparative Example 3 The granules prepared in Preparation Example 1 were applied to one side of an aluminum current collector and rolled to prepare a positive electrode having a thickness of about 200 μm. A lithium foil having a thickness of about 150 μm was prepared as a negative electrode, and a porous polyethylene was prepared as a separator. An electrode assembly was prepared by interposing the porous polyethylene separator between the positive and negative electrodes. The electrode assembly was placed inside a battery case, and an electrolyte was injected into the case to prepare a lithium secondary battery. The electrolyte was prepared by dissolving lithium hexafluorophosphate (LiPF6) at a concentration of 1.0 M in an organic solvent consisting of ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate (EC / DMC / EMC mixed volume ratio = 3 / 4 / 3).

[0059] Comparative Example 4 A lithium secondary battery was manufactured in the same manner as in Comparative Example 3, except that the granules prepared in Comparative Preparation Example 1 were used instead of Preparation Example 1 when preparing the positive electrode.

[0060] Comparative Example 5 A lithium secondary battery was manufactured in the same manner as in Comparative Example 3, except that the granules prepared in Comparative Preparation Example 2 were used instead of Preparation Example 1 when manufacturing the positive electrode.

[0061] Experimental example: Performance evaluation of manufactured batteries The batteries manufactured in Example 1 and Comparative Examples 1 to 5 were charged / discharged, and the discharge capacity (mAh / g) and Coulombic efficiency (%) after 10 cycles were measured and shown in Table 1. Meanwhile, when evaluating the battery performance, the batteries were charged / discharged at 0.05 C at a temperature of 60° C., and the 10 cycles were completed in a discharged state (a state in which lithium was not present at the negative electrode), and the discharge capacity (mAh / g) and Coulombic efficiency (%) were measured.

[0062] Charging conditions: 0.05C, 4.25V CC / CV, 0.01C cut-off Discharge conditions: 0.05C, 3V The results are shown in Table 1 below.

[0063] [Table 1]

[0064] According to Table 1, in the all-solid-state batteries, the all-solid-state battery of Example 1 exhibited superior effects in Coulombic efficiency and discharge capacity even after 10 cycles compared to the all-solid-state batteries of Comparative Examples 1 and 2. However, when the same active material granules were evaluated in a lithium secondary battery using a liquid electrolyte, the lithium secondary battery of Comparative Example 3 corresponding to Example 1 did not exhibit superior effects in Coulombic efficiency and discharge capacity after 10 cycles compared to the lithium secondary batteries of Comparative Examples 4 and 5 corresponding to Comparative Examples 1 and 2, respectively, and instead exhibited lower Coulombic efficiency and discharge capacity.

[0065] In an all-solid-state battery, the electrode is impregnated with a ductile sulfide-based electrolyte, dried and rolled, and the porosity of the electrode is significantly reduced compared to a lithium secondary battery using a liquid electrolyte. The functionality of the active material granules may change depending on the environment inside the battery, and the electrodes according to the present invention, such as Example 1, have improved functionality and can be suitably applied, particularly in all-solid-state batteries.

[0066] Any mere variations or modifications of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

Claims

1. An electrode for an all-solid-state battery comprising granules coated with a sulfide-based solid electrolyte, The granules include an active material, a conductive material, and a binder; the conductive material is a carbon nanotube having a diameter of 1 nm to 10 nm; The carbon nanotubes have a BET specific surface area of ​​400 m 2 / g to 1000 m 2 / g; The granules have a porosity of 10% to 40%.

2. An electrode for an all-solid-state battery comprising granules coated with a sulfide-based solid electrolyte, The granules include an active material, a conductive material, and a binder; the conductive material is a carbon nanotube having a diameter of 1 nm to 10 nm; An electrode for an all-solid-state battery, characterized in that when the internal diameter of the granule is divided into a first region, a second region, and a third region in the order from the center of the granule to the outside of the granule at equal intervals, the content of the conductive material in the granule increases in the order of the first region, the second region, and the third region.

3. The carbon nanotube is 400 m ２ / g to 1000m ２ The electrode for an all-solid-state battery according to claim 2 , characterized in that it has a BET specific surface area of ​​1000 nm / g.

4. 3. The electrode for an all-solid-state battery according to claim 1, wherein the carbon nanotube is a single-walled carbon nanotube.

5. The electrode for an all-solid-state battery according to claim 1 or 2, wherein the granules are spherical particles having a diameter of 30 μm to 150 μm.

6. The electrode for an all-solid-state battery according to claim 2, wherein the granules have a porosity of 10% to 40%.

7. The electrode for an all-solid-state battery is a positive electrode, The 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 , 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 The electrode for an all-solid-state battery according to claim 1 or 2, wherein z is selected from the group consisting of (0<z<2) and combinations thereof.

8. The binder is an organic binder, 3. The electrode for an all-solid-state battery according to claim 1 or 2, characterized in that the organic binder is 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-butylene rubber, and fluororubber.

9. 3. The electrode for an all-solid-state battery according to claim 1, wherein the granules contain 85% by weight to 99.8% by weight of an active material, 0.1% by weight to 10% by weight of a binder, and 0.1% by weight to 10% by weight of a conductive material.

10. The electrode for an all-solid-state battery according to claim 2 , wherein the third region of the granule is 40% by weight or more based on the total content of the conductive material in the granule.

11. 3. The electrode for an all-solid-state battery according to claim 1, wherein the electrode active material layer including the granules coated with the sulfide-based solid electrolyte in the electrode for an all-solid-state battery has a thickness of 100 μm to 300 μm.

12. 3. The electrode for an all-solid-state battery according to claim 1, wherein the electrode active material layer including granules coated with a sulfide-based solid electrolyte in the electrode for an all-solid-state battery includes 20 wt % to 40 wt % of the sulfide-based solid electrolyte based on the content of the granules.

13. An all-solid-state battery comprising the electrode for an all-solid-state battery according to claim 1 or 2 as a positive electrode or a negative electrode.

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