Electrodes for all-solid-state batteries

Abstract

An electrode for an all-solid-state battery is provided, comprising granules coated with a sulfide-based solid electrolyte. The granules comprise an active material, a conductive material, and a binder, and the conductive material is carbon black having an average particle size of 120 nm to 200 nm. The carbon black aggregates to form secondary particles, and the secondary particles have a particle size of 600 nm to 1,100 nm. The granules containing the conductive material not only have high electrical conductivity, but also improve the performance of the battery when applied to a battery in one electrode configuration.

Description

[Technical Field]

[0001] This application relates to an electrode for an all-solid-state battery. Specifically, it relates to a positive electrode for an all-solid-state battery comprising granules coated with a sulfide-based solid electrolyte.

[0002] This application claims priority under Korean Patent Application No. 10-2022-0110540 dated September 1, 2022, and incorporates all the contents disclosed in the said Korean Patent Application as part of this Specification. [Background technology]

[0003] From the perspectives of battery capacity, safety, output, scaling up, and miniaturization, various types of batteries are currently being researched that can overcome the limitations of lithium-ion secondary batteries.

[0004] Typically, metal-air batteries, which have a much larger theoretical capacity than lithium-ion batteries; all-solid-state batteries, which pose no risk of explosion in terms of safety; supercapacitors, which offer greater power output; NaS batteries or RFB (redox flow batteries), which are designed for larger sizes; and thin-film batteries, which are designed for ultra-miniaturization, are all being continuously researched in academia and industry.

[0005] Of these, all-solid-state batteries refer to batteries in which the liquid electrolyte used in conventional lithium secondary batteries is replaced with a solid. Because they do not use flammable solvents within the battery, there is absolutely no risk of ignition or explosion due to the decomposition reaction of conventional electrolytes, thus significantly improving safety. In addition, because lithium metal or lithium alloy can be used as the negative electrode material, there is an advantage in that the energy density relative to the mass and volume of the battery can be dramatically improved.

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

[0007] Sulfide-based solid electrolytes are among the 10 solid electrolytes. -3 ~10 -2 It possesses high ionic conductivity (S / cm), is ductile, and makes good contact with interfaces, which is advantageous for improving resistance. However, it is sensitive to moisture, generating H2S gas when it comes into contact with water, so a very dry environment must be created during manufacturing. Furthermore, it is necessary to improve the aggregation of the active material and solid electrolyte, and a reduction in porosity is required to produce high-density electrodes.

[0008] Therefore, in order to solve the problems faced in the field of the present invention, the inventors have continuously researched electrodes for all-solid-state batteries and have completed the present invention. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent Publication No. 10-2016-0146737 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The aim is to provide an electrode for an all-solid-state battery that includes granules coated with a sulfide-based solid electrolyte, and which, when applied as an electrode for an all-solid-state battery, can improve the performance of the battery. [Means for solving the problem]

[0011] According to the 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 carbon black having an average particle size of 120 nm to 200 nm.

[0012] In one embodiment of the present invention, the carbon black has a BET specific surface area of 15 m 2 / g to 35 m 2 / g.

[0013] In one embodiment of the present invention, the carbon black has a DBP absorption rate of 70 ml / 100 g to 100 ml / 100 g.

[0014] In one embodiment of the present invention, the carbon black aggregates to form secondary particles, and the secondary particles have a particle size of 600 nm to 1,100 nm.

[0015] In one embodiment of the present invention, the particles are spherical particles having a diameter of 30 μm to 150 μm, which is a feature of the electrode for all-solid-state battery.

[0016] In one embodiment of the present invention, the particles have a porosity of 20% to 40%, which is a feature of the electrode for all-solid-state battery.

[0017] In one embodiment 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 (0 < y < 1), LiNi 1-y Mn y [[ID=?]] 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 It is selected from the group consisting of O4(0 < z < 2) and combinations thereof.

[0018] 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, polyvinyl pyrrolidone, polyimide, polyamideimide, polyethylene, polypropylene, ethylene - propylene - diene monomer (EPDM), sulfonated EPDM, styrene - butadiene rubber, and fluorine rubber.

[0019] In one embodiment of the present invention, the granules contain 85 wt% - 99.8 wt% of active material, 0.1 wt% - 10 wt% of binder, and 0.1 wt% - 10 wt% of conductive material.

[0020] In one embodiment of the present invention, in the electrode for all - solid - state battery, the electrode active material layer containing granules coated with a sulfide - based solid electrolyte has a thickness of 100 μm - 300 μm.

[0021] In one embodiment of the present invention, in the electrode for all - solid - state battery, the electrode active material layer containing granules coated with a sulfide - based solid electrolyte contains 10 wt% - 30 wt% of sulfide - based solid electrolyte based on the content of the granules.

[0022] In one embodiment of the present invention, when the granules are divided at the same interval of the inner diameter of the granules and separated into a first region, a second region, and a third region in order from the center of the granules to the outside of the granules, the content of the conductive material in the granules increases in the order of the first region, the second region, and the third region.

[0023] In one embodiment of the present invention, the granules have an R value of 5 or less, and the R value is defined by the following formula 1.

[0024] According to a second aspect of the present invention, The present invention provides an all-solid-state battery that includes the aforementioned all-solid-state battery electrode as either the positive or negative electrode. [Effects of the Invention]

[0025] In an electrode for an all-solid-state battery containing granules coated with a sulfide-based solid electrolyte, the granules contain an active material, a conductive material, and a binder. By specifying the physical properties of the primary or secondary particles of carbon black, which is the conductive material contained in the granules, not only can the electrical conductivity of the granules be improved, but the performance of the battery to which the granules are applied can also be improved. [Brief explanation of the drawing]

[0026] [Figure 1a] This is an SEM image (1,000x magnification) of the granules from Manufacturing Example 1, produced according to Experimental Example 1. [Figure 1b] This is an SEM image (5,000x magnification) of the granules from Manufacturing Example 1, produced according to Experimental Example 1. [Figure 2a] This is an SEM image (1,000x magnification) of the granules from comparative manufacturing example 1, based on experimental example 1. [Figure 2b] This is an SEM image (5,000x magnification) of the granules from comparative manufacturing example 1, based on experimental example 1. [Figure 3] This diagram schematically shows the locations of the first region (A), the second region (B), and the third region (C) in the granule. [Modes for carrying out the invention]

[0027] All embodiments provided in accordance with the present invention can 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.

[0028] If the measurement conditions and methods for any physical properties described herein are not specifically described, such physical properties shall be measured in accordance with the measurement conditions and methods commonly used by ordinary artisans in that field.

[0029] In one aspect of the present invention, an electrode for an all-solid-state battery is provided, comprising granules coated with a sulfide-based solid electrolyte. The granules are spherical particles comprising an active material, a conductive material, and a binder. Here, "spherical" does not mean perfectly spherical in the strict sense, but is used as a general concept that includes particles with a round shape. The active material, in the form of fine powder particles, is bound together with the conductive material, which is either a primary or secondary particle, by a binder solution to grow into particles having a specific range of specifications. The conductive material may be applied as primary particles, as secondary particles, or in a mixed form of primary and secondary particles.

[0030] According to one embodiment of the present invention, the granules are spherical particles having a diameter of 30 μm to 150 μm. Here, the term "spherical particle" does not mean a perfectly spherical particle; therefore, the diameter refers to the largest distance between any point on the particle surface and any other 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, 150 μm or less, 145 μm or less, 140 μm or less, 135 μm or less, 130 μm or less, 125 μm or less, 120 μm or less, or 30 μm to 150 μm, 40 μm to 140 μm, or 50 μm to 120 μm. If the diameter of the granules is less than the range mentioned above, the voids within the granule layer are small, reducing the amount of sulfide-based solid electrolyte that penetrates and coats between the granules, which may result in a lack of significant improvement in battery performance. If the diameter of the granules exceeds the range mentioned above, the distance between the surface in contact with the sulfide-based solid electrolyte and the center of the granules increases, which may also result in a lack of significant improvement in battery performance.

[0031] 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 the all-solid-state battery may be a positive electrode.

[0032] When the electrode is a negative electrode, the electrode active material contained in the granule may be any material that can be used as a negative electrode active material of a lithium ion secondary battery. For example, the negative electrode active material may be carbon such as 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, elements of Group 1, Group 2, Group 3 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 selected therefrom may be used. According to one embodiment of the present invention, the negative electrode active material may contain a carbon-based material and / or Si.

[0033] When the electrode is a positive electrode, the electrode active material contained in the granule may be used without limitation as long as it can be used as a positive electrode active material of 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 embodiment 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(0 < y < 1), LiNi 1-y Mn y O2(0 < y < 1), Li(Ni a Cob 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.

[0034] The conductive material contained in the granules according to one embodiment of the present invention is carbon black having an average particle size of 120 nm to 200 nm. Here, the average particle size is the arithmetic average value of the particle sizes. Specifically, the average particle size of the carbon black is 120 nm or more, 125 nm or more, 130 nm or more, 135 nm or more, and 200 nm or less, 190 nm or less, 180 nm or less, 170 nm or less, and may be 120 nm to 200 nm, 130 nm to 190 nm, 135 nm to 170 nm. When the diameter of the carbon black is less than the above range, the external area of the carbon black is small, and it is difficult for the conductive material to form a structure effective for exhibiting functionality among a large number of active material particles. When the diameter of the carbon black exceeds the above range, it is difficult for the conductive material to be dispersed and located at an appropriate position. In addition, the conductive material having a particle size within the above-described range helps to form secondary particles having preferable physical properties.

[0035] According to one embodiment of the present invention, the carbon black is 15 m 2 / g to 35 m 2 / g has a BET specific surface area. The BET specific surface area is the specific surface area measured by the BET method. Specifically, the BET specific surface area of the carbon black is 15 m 2 / g or more, 16 m 2 / g or more, 17 m 2 / g or more, 18 m 2 / g or more, 19 m 2 / g or more, 20 m 2 / g or more, and 35 m 2 / g or less, 34 m 2 / g or less, 33 m 2 / g or less, 32 m 2 / g or less, 31 m 2 / g or less, 30 m2 / g or less, 15m 2 / g~35m 2 / g, 17m 2 / g~33m 2 / g, 20m 2 / g~30m 2 It may also be / g. If the BET specific surface area of ​​the carbon black is less than the range mentioned above, the area in contact with the active material decreases relative to the weight of the carbon black, which may make it difficult to ensure functionality. If the BET specific surface area of ​​the carbon black exceeds the range mentioned above, it does not come into contact with the active material or solid electrolyte as easily as the excess specific surface area, which may make it difficult to ensure functionality. Furthermore, conductive materials having particle sizes within the range mentioned above are useful for forming secondary particles with desirable physical properties.

[0036] According to one embodiment of the present invention, the carbon black used as a conductive material aggregates to form secondary particles, the secondary particles having a particle size of 600 nm to 1,100 nm. In this specification, carbon black before aggregation into secondary particles can be expressed as primary particles. The secondary particles may aggregate in various forms during aggregation, and the particle size refers to the largest distance from any point on the particle surface to any other point on the surface. When carbon black is aggregated and used in the form of secondary particles, a highly functional structure can be formed because electrolytes and active materials can access the voids between the carbon black particles while maintaining the conductive network between each carbon black particle constituting the secondary particle. Specifically, the particle size of the secondary particles may be 600 nm or more, 650 nm or more, 700 nm or more, 1,100 nm or less, 1,000 nm or less, 900 nm or less, 600 nm to 1,100 nm, 650 nm to 1,000 nm, or 700 nm to 900 nm. If the particle size of the secondary particles is less than the range mentioned above, the functionality obtained by forming the secondary particles may be minimal, and if the particle size of the secondary particles exceeds the range mentioned above, the conductive material may aggregate excessively, making it difficult to efficiently disperse the conductive material throughout the granules.

[0037] According to one embodiment of the present invention, the carbon black used as the conductive material has a DBP absorption rate of 70 ml / 100 g to 100 ml / 100 g. The DBP absorption rate is measured by the change in torque generated by impregnation with DBP (dibutyl phthalate), which is a plasticizer, and the DBP absorption rate of the conductive material can affect the formation of secondary particles by the conductive material. Specifically, the DBP absorption rate of the carbon black is 70 ml / 100g or more, 71 ml / 100g or more, 72 ml / 100g or more, 73 ml / 100g or more, 74 ml / 100g or more, 75 ml / 100g or more, 100 ml / 100g or less, 98 ml / 100g or less, 96 ml / 100g or less, 94 ml / 100g or less, 92 ml / 100g or less, 90 ml / 100g or less, and may be between 70 ml / 100g and 100 ml / 100g, 73 ml / 100g and 94 ml / 100g, or between 75 ml / 100g and 90 ml / 100g. Carbon black having a DBP absorption rate within the above range is useful for forming secondary particles with desirable physical properties.

[0038] In one embodiment of the present invention, the binder contained in the granules is mixed with the active material, which is a fine powder, and the conductive material, which is a primary or secondary particle, to bind the components together and help the particles grow. Since sulfide-based solid electrolytes have properties that are sensitive to moisture, such as generating H2S gas when they come into contact with water, it is preferable to remove as much moisture as possible from the time the granules are formed. According to one embodiment of the present invention, the binder is an organic binder. The organic binder means a binder that dissolves or disperses in an organic solvent, particularly N-methylpyrrolidone (NMP), and is distinguished from aqueous binders that use water as a solvent or dispersion medium. Specifically, the organic binder may be selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene 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 to these.

[0039] According to one embodiment of the present invention, in the granules, the active material is 85% to 99.8% by weight, specifically 88% to 99.5% by weight, more specifically 90% to 99.3% by weight; the binder is 0.1% to 10% by weight, specifically 0.2% to 8% by weight, more specifically 0.3% to 7% by weight; and the conductive material is 0.1% to 10% by weight, specifically 0.15% to 8% by weight, more specifically 0.2% to 5% by weight. Adjusting the content of the active material, binder, and conductive material within the aforementioned ranges is advantageous for improving the performance of the battery.

[0040] According to one embodiment of the present invention, the granules have a porosity of 20% to 40%. The porosity of the granules refers to the volume ratio of voids in the granules. Specifically, the porosity of the granules may be 20% or more, 21% or more, 22% or more, 23% or more, 24% or more, 25% or more, 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, or 35% or less. If the porosity of the granules is less than the above range, the sulfide-based solid electrolyte does not easily come into close contact with the granules, and the improvement in battery performance may not be significant. If the porosity of the granules exceeds the above range, the amount of active material decreases compared to the volume of the granules, and the improvement in battery performance may not be significant, as it is difficult to provide electrodes with a high load of active material.

[0041] Generally, when manufacturing granules, a binder solution is added along with powdered fine particles of active material and conductive material to grow the granule size to a specific level. During this process, the inside of the apparatus may rotate to sphericalize the granules and separate them. Due to this rotation, centrifugal force acts on the granules, and the constituent components of the granules may be concentrated on the outside of the granules rather than in the center. However, when manufacturing granules according to one embodiment of the present invention, the movement of the conductive material toward the surface of the granules during the high-temperature solvent drying process can be minimized, allowing for a uniform distribution of the conductive material within the granules. This can be confirmed through the SEM images in Figures 1 and 2 from Experimental Example 1 below. As shown in Figure 2, if a large amount of conductive material moves toward the surface of the granules, not only does the porosity of the granules decrease, but the active material within the granules is not easily exposed to the electrolyte, which can lead to a decrease in battery performance.

[0042] Figure 3 schematically shows the shape of granules according to one embodiment of the present invention. As shown in Figure 3, the interior of the granules can be separated into a first region (region A), a second region (region B), and a third region (region C). The first, second, and third regions are separated by dividing the internal diameter of the granule at equal intervals. The first region is located at the very center of the granule, the third region is located at the very outermost part of the granule, and the second region is located between the first and third regions. According to one embodiment of the present invention, the content of the conductive material in the granules increases in the order of the first region, the second region, and the third region.

[0043] According to one embodiment of the present invention, the granules have R values ​​of 5 or less, 4.5 or less, and 4 or less. Here, the R value is a numerical representation of the change in the content of conductive material between adjacent regions, and is defined by the following formula 1.

[0044] [Formula 1]

number

[0045] Here, r A is the content (%) of conductive material in the first region, and r B This is the content (%) of conductive material in the second region, and r C This represents the conductive material content (%) in the third region. The conductive material content in each region is based on the total conductive material content of the granules, so r A , r B , r C The sum is 100%. Basically, the content of the conductive material in one embodiment of the present invention increases in the order of the first region, second region, and third region, so the R value is 1 or greater. If the deviation of the conductive material content between each region is large, the R value may be high, and if the deviation of the conductive material content between each region is small, the R value may be low. When the R value is low, the conductive material is distributed uniformly and may help to improve the electrical conductivity of the entire granule, but the electrical conductivity of the granule is affected not only by the R value but also by the size, shape, and content of the conductive material.

[0046] In the all-solid-state electrode, the solid electrolyte is coated on at least a part or all of the surface of the aforementioned particles. The solid electrolyte may be a polymer solid electrolyte formed by adding a polymer resin to a solvated lithium salt, an organic electrolyte solution containing an organic solvent and a lithium salt, an ionic liquid, a monomer or an oligomer contained in a polymer resin, or a polymer gel electrolyte. The solid electrolyte may be one or more selected from polymer-based solid electrolytes, sulfide-based solid electrolytes, and oxide-based solid electrolytes. According to one embodiment of the present invention, a sulfide-based solid electrolyte is used as the solid electrolyte. In the all-solid-state electrode, the sulfide-based solid electrolyte is applied after being impregnated with a particle layer composed of the aforementioned particles in a sulfide-based electrolyte and then dried.

[0047] According to one embodiment of the present invention, the lithium salt can be represented as Li + X - There is no particular limitation on the anion of such a lithium salt, but 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 - and the like. In one embodiment of the present invention, the sulfide-based solid electrolyte 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-P-S-based glass or Li-P-S-based glass ceramic. Non-limiting examples of these 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, etc., and one or more of these may be included.

[0048] The electrode for all-solid-state battery according to one embodiment of the present invention may be manufactured by loading particles on a current collector to produce a sheet-like particle layer, and then impregnating the particle layer with a sulfide-based electrolyte and drying it. At this time, the current collector exhibits electrical conductivity such as a metal plate, and an electrode known in the art may be appropriately used according to the polarity of the battery.

[0049] According to one embodiment of the present invention, in the electrode for the all-solid-state battery, the electrode active material layer containing granules coated with a sulfide-based solid electrolyte has a thickness of 100 μm to 300 μm. Here, the electrode active material layer refers to a sheet-like layer applied on the current collector, excluding the current collector itself, when a 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 decreases, and the improvement in battery performance may not be significant. If the thickness of the electrode active material layer exceeds the above range, the durability of the electrode decreases, and the improvement in battery performance may not be significant.

[0050] According to one embodiment of the present invention, in the electrode for the all-solid-state battery, the electrode active material layer containing granules coated with a sulfide-based solid electrolyte contains 10% to 30% 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 10% or more by weight, 11% or more by weight, 12% or more by weight, 13% or more by weight, 14% or more by weight, 15% or more by weight, or 30% or less by weight, 29% or less by weight, 28% or less by weight, 27% or less by weight, 26% or less by weight, or 25% or less by weight. If the content of the sulfide-based solid electrolyte is less than the above range, electron transfer between the electrolyte and the active material is not easy in the all-solid-state battery, and the improvement in battery performance may not be significant. If the content of the sulfide-based solid electrolyte exceeds the above range, the loading amount of the active material is relatively reduced, and the improvement in battery performance may not be significant.

[0051] In one aspect of the present invention, an all-solid-state battery is provided, comprising the aforementioned electrodes for all-solid-state batteries as a positive electrode and / or a negative electrode. In constructing the all-solid-state battery, in addition to the solid electrolyte contained in the electrodes, another solid electrolyte layer may be introduced between the positive and negative electrodes, and such a solid electrolyte layer can also serve a role similar to that of a separator membrane in a typical lithium secondary battery. The aforementioned electrodes may, in some cases, be used together with a liquid electrolyte and utilized as a semi-solid-state battery, in which case another polymer separator membrane may be required.

[0052] The polymer separation membrane is interposed between the negative electrode and the positive electrode, and serves to electrically insulate the negative electrode and the positive electrode while simultaneously allowing lithium ions to pass through. The polymer separation membrane can be any polymer separator membrane used in the field of conventional all-solid-state batteries, and is not particularly limited.

[0053] In one aspect of the present invention, a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source are provided.

[0054] Specific examples of the aforementioned devices 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 power storage systems.

[0055] The following are preferred embodiments to aid in understanding the present invention, but these embodiments are provided to make the present invention easier to understand, and the present invention is not limited thereto.

[0056] Manufacturing example: Production of granules containing active material Manufacturing Example 1 LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), carbon black as conductive material (average particle size (D 50 ): approx. 150nm, BET specific surface area: approx. 25m 2 Secondary particles (particle size: approximately 800 nm) were agglomerated from ( / g, DBP absorption rate: approximately 81 ml / 100 g), and polyvinylidene fluoride (PVDF) was used as a binder. A slurry was prepared by mixing these particles in N-methylpyrrolidone solvent in a weight ratio of 94:3:3 (active material: conductive material: binder), and then granules with a diameter of approximately 60 μm (porosity: 31%) were produced by spray drying.

[0057] Comparative Manufacturing Example 1 LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), carbon black as conductive material (average particle size (D 50 ): approx. 30nm, BET specific surface area: approx. 120m 2 Secondary particles (particle size: approximately 150 nm) were agglomerated from ( / g, DBP absorption rate: approximately 190 ml / 100 g), and polyvinylidene fluoride (PVDF) was used as a binder. A slurry was prepared by mixing these particles in N-methylpyrrolidone solvent in a weight ratio of 94:3:3 (active material: conductive material: binder), and then granules with a diameter of approximately 60 μm (porosity: 15%) were produced by spray drying.

[0058] Comparative Manufacturing Example 2 LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), carbon black as conductive material (average particle size (D 50 ): approx. 40nm, BET specific surface area: approx. 90m 2Secondary particles (particle size: approximately 750 nm) were agglomerated from ( / g, DBP absorption rate: approximately 230 ml / 100 g), and polyvinylidene fluoride (PVDF) was used as a binder. A slurry was prepared by mixing these particles in N-methylpyrrolidone solvent in a weight ratio of 94:3:3 (active material: conductive material: binder), and then granules with a diameter of approximately 60 μm (porosity: 19%) were produced by spray drying.

[0059] Comparative Manufacturing Example 3 LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622), carbon black as conductive material (average particle size (D 50 ): approx. 280nm, BET specific surface area: approx. 9m 2 Secondary particles (particle size: approximately 3,000 nm) were agglomerated from ( / g, DBP absorption rate: approximately 40 ml / 100 g) and polyvinylidene fluoride (PVDF) was used as a binder. A slurry was prepared by mixing these particles in N-methylpyrrolidone solvent in a weight ratio of 94:3:3 (active material: conductive material: binder), and then granules with a diameter of approximately 60 μm (porosity: 37%) were produced by spray drying.

[0060] The physical properties of the granules produced in Production Example 1 and Comparative Production Examples 1-3 are summarized in Table 1 below.

[0061] [Table 1]

[0062] 1) Average particle size (nm) of primary conductive material particles: After measuring the particle size of each particle distinguishable in the SEM (Scanning Electron Microscope) image, the arithmetic mean of the measured values ​​was calculated.

[0063] 2) BET specific surface area (m²) of primary conductive particles 2 ( / g): Calculated from the amount of mass gas adsorbed under liquid nitrogen temperature (77K) using BELSORP-mino II from BEL Japan.

[0064] 3) DBP absorption rate of primary conductive material particles (ml / 100g): Using an oil absorption measuring device (Asahi's S-500), DBP (dibutyl phthalate), a plasticizer, was mixed with the conductive material, and the change in torque generated by plasticizer impregnation was measured. The amount of oil absorbed at which the viscosity expressed as the torque value reached its maximum was calculated as the DBP adsorption value.

[0065] 4) Particle size (nm) of conductive material secondary particles: Measured using a wet method with a particle size analyzer (Malvern's Mastersizer).

[0066] 5) Granule porosity (%): Measured using a mercury porosity analyzer (Autopore, Micromeritics).

[0067] 6) Conductive material content (%) in the first, second, or third granule region: The ratio of conductive material content in a specific region to the total conductive material within the granule cross-section was calculated using SEM, EDS (Energy Dispersive Spectroscopy) measurements and image analysis programs.

[0068] 7) R value of granular conductive material: Calculated using formula 1 based on the result value in 6) above.

[0069] 8) Electrical conductivity of granules (%): After measuring using a 4-Probe powder electrical conductivity measuring electrode (Mitsubishi Chemical's powder resistance system (MCP-PD51)), the %) was calculated as a percentage based on Production Example 1.

[0070] Example: Manufacturing of electrodes and batteries containing the manufactured granules Example 1 The granules produced in Production Example 1 were coated onto one side of an aluminum current collector, rolled, and then impregnated with a Li2S-P2S5 sulfide-based electrolyte. After drying and rolling, a positive electrode with a thickness of approximately 130 μm was produced (the sulfide-based electrolyte contained approximately 20% by weight relative to the granules). A slurry was produced by mixing Li2S-LiCl-P2S5 with a polyvinylidene fluoride (PVDF) solution (a solution in which PVDF and toluene are mixed in a weight ratio of 8:92). This slurry was then coated onto a lithium foil (Li foil) with a thickness of approximately 50 μm to a thickness of approximately 100 μm to produce a solid electrolyte and a negative electrode containing it. The positive and negative electrodes were stacked and compressed to produce an electrode assembly, which was then placed inside a battery case to produce an all-solid-state battery.

[0071] Comparative Example 1 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the granules manufactured in Comparative Manufacturing Example 1 were used instead of those in Manufacturing Example 1 during the manufacturing of the positive electrode.

[0072] Comparative Example 2 An all-solid-state battery was manufactured in the same manner as in Example 1, except that the granules manufactured in Comparative Manufacturing Example 2 were used instead of those in Manufacturing Example 1 during the manufacturing of the positive electrode.

[0073] Comparative Example 3 An all-solid-state battery was manufactured in the same manner as in Example 1, except that granules manufactured in Comparative Manufacturing Example 3 were used instead of those in Manufacturing Example 1 during the manufacturing of the positive electrode.

[0074] Experimental Examples: Evaluation of Manufacturing Examples and Embodiments Experimental Example 1: SEM image of granules SEM images were taken of the granules produced in Production Example 1 and Comparative Production Example 1, and are shown in Figure 1 (Production Example 1) and Figure 2 (Comparative Production Example 1). Specifically, in Figures 1a and 2a, the overall shape of the granules was confirmed by measuring at a magnification of ×1,000, and in Figures 1b and 2b, the distribution of conductive material on the active material surface of the granules was confirmed by measuring at a magnification of ×5,000.

[0075] According to Figures 1a and 1b, the conductive material was distributed on the surface of the active material in the form of more distinct particles, and each active material particle was clearly distinguishable from the granules. On the other hand, according to Figures 2a and 2b, at this magnification, the conductive material consisted of very fine particles that covered the active material particles to such an extent that the surface of the active material was not visible, and the boundary between the granules and active material particles was ambiguous.

[0076] Experiment Example 2: Battery Performance Evaluation The batteries of Example 1 and Comparative Examples 1-3 were discharged at 0.1C and 1.0C, respectively, and the discharge capacity ratio (1.0C discharge capacity / 0.1C discharge capacity × 100, %) was measured. The results are shown in Table 2 below.

[0077] [Table 2]

[0078] According to Tables 1 and 2, the granules produced in Manufacturing Example 1 had higher electrical conductivity than the granules produced in Comparative Manufacturing Examples 1 to 3. Furthermore, the battery of Example 1, which included electrodes produced using the granules of Manufacturing Example 1, did not experience a significant decrease in battery performance even under higher C-rate conditions compared to the batteries of Comparative Examples 1 to 3, which included electrodes produced using the granules of Comparative Manufacturing Examples 1 to 3.

[0079] Any mere modification or alteration of the present invention falls within the scope of the present invention, and the specific scope of protection of the present invention is 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 comprise an active material, a conductive material, and a binder. The conductive material is carbon black having an average particle size of 120 nm to 200 nm. The carbon black aggregates to form secondary particles. The secondary particles have a particle size of 600 nm to 1,100 nm and are electrodes for all-solid-state batteries.

2. The carbon black is 15m ２ / g ~ 35m ２ An electrode for an all-solid-state battery according to claim 1, characterized by having a BET specific surface area of ​​1 / g.

3. The electrode for an all-solid-state battery according to claim 1, characterized in that the carbon black has a DBP absorption rate of 70 ml / 100 g to 100 ml / 100 g.

4. The electrode for an all-solid-state battery according to claim 1, characterized in that the granules are spherical particles having a diameter of 30 μm to 150 μm.

5. The electrode for an all-solid-state battery according to claim 1, characterized in that the granules have a porosity of 20% to 40%.

6. The electrode for the all-solid-state battery is the 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 (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 The electrode for an all - solid - state battery according to claim 1, characterized in that it is selected from the group consisting of these and combinations thereof.

7. The aforementioned binder is an organic binder. The electrode for an all-solid-state battery according to claim 1, characterized in that the organic binder is selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene 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.

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

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

10. The electrode for an all-solid-state battery according to claim 1, characterized in that the electrode active material layer containing granules coated with a sulfide-based solid electrolyte contains 10% to 30% by weight of the sulfide-based solid electrolyte based on the content of the granules.

11. The electrode for an all-solid-state battery according to claim 1, characterized in that when the granules are divided into first, second, and third regions in order from the center to the outside of the granules by dividing the inner diameter of the granules into equal intervals, the content of the conductive material in the granules increases in the order of first region, second region, and third region.

12. The electrode for an all-solid-state battery according to claim 11, characterized in that the granules have an R value of 5 or less, and the R value is defined by the following formula 1: [Formula 1] [Math 1] Here, r Ａ is the content (%) of conductive material in the first region, and r Ｂ is the content (%) of conductive material in the second region, and r Ｃ This represents the conductive material content (%) in the third region, and the conductive material content in each region is based on the total conductive material content of the granules.

13. A solid-state battery comprising the electrode for solid-state batteries described in claim 1 as the positive electrode or the negative electrode.

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