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

Abstract

The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery comprising same. More specifically, in the present invention, the positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive. By allowing the particle diameter of the porous carbon additive to be included between the particle diameter of the positive electrode active material and the particle diameter of the sulfide-based solid electrolyte, the interface between the positive electrode active material and the sulfide-based solid electrolyte can be increased and at the same time the porosity of the entire positive electrode can be reduced, thereby exhibiting the effect of increasing the energy density of a cell without decreasing the cell performance while maintaining the conductivity of a bipolar electrode.

Description

Cathode for all-solid-state battery and all-solid-state battery containing same

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0094993, dated July 21, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same.

[0003] Various batteries are being studied to overcome the limitations of current lithium secondary batteries in terms of battery capacity, safety, output, large-scale development, and miniaturization.

[0004] Representative examples include metal-air batteries with much larger theoretical capacity than lithium secondary batteries, all-solid-state batteries with no risk of explosion in terms of safety, supercapacitors for output, NaS batteries or RFBs (redox flow batteries) for large-scale applications, and thin film batteries for miniaturization, all of which are being continuously researched in academia and industry.

[0005] Among the various next-generation batteries, all-solid-state batteries are batteries that replace the liquid electrolytes used in conventional lithium secondary batteries with solid electrolytes. Since they do not use flammable solvents within the battery, there is no risk of fire or explosion due to decomposition reactions of conventional electrolytes, which can significantly improve safety. Furthermore, among all-solid-state batteries, technological development is continuing for sulfide-based all-solid-state batteries, which have high ionic conductivity of solid electrolytes and can theoretically achieve high energy densities of over 900 Wh / L. Here, the term "sulfide-based all-solid-state battery" refers to an all-solid-state battery that contains a sulfide-based solid electrolyte.

[0006] In all-solid-state battery systems, lithium ion conduction does not occur through the liquid electrolyte contained in conventional lithium-ion batteries (LIBs). Therefore, when manufacturing a cathode for a sulfide-based all-solid-state battery, small-diameter sulfide-based solid electrolyte particles must be added to the inside of the cathode to increase the contact interface between the cathode active material and the sulfide-based solid electrolyte particles, thereby increasing lithium ion conduction. Furthermore, to improve energy density, the physical contact between the cathode active material, sulfide-based solid electrolyte particles, and other battery components within the cathode must be promoted, and the porosity of the cathode after rolling must be reduced, which must be maintained during charge and discharge.

[0007] Accordingly, there is a constant need for technological development that can further reduce porosity in the positive electrode of a sulfide-based all-solid-state battery and thereby improve the performance of the all-solid-state battery.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] (Patent Document 1)

[0011] Korean Patent Publication No. 2016-0118597

[0012] The present inventors have conducted various studies to solve the above problems and have confirmed that when manufacturing a positive electrode active material layer of an all-solid-state battery positive electrode, a positive electrode active material, a sulfide-based solid electrolyte, a conductive agent, and a porous carbon additive are used, and the particle size of the porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte so as to fill the pores between the particles of the positive electrode active material and the sulfide-based solid electrolyte, and at the same time, the specific surface area of ​​the porous carbon additive is limited to a certain level or less, the porosity of the positive electrode active material layer is reduced, thereby improving the energy density of the all-solid-state battery.

[0013] Accordingly, an object of the present invention is to provide a positive electrode for an all-solid-state battery with reduced porosity.

[0014] Another object of the present invention is to provide an all-solid-state battery including the positive electrode for an all-solid-state battery with reduced porosity.

[0015] In order to achieve the above object, the present invention provides a positive electrode for an all-solid-state battery comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive,

[0016] The particle size of the above porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte,

[0017] The above porous carbon additive provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is a low-surface-area porous carbon additive having a BET surface area of ​​100 m2 / g or less.

[0018] The present invention also provides a positive electrode for an all-solid-state battery, wherein the BET specific surface area of ​​the porous carbon additive is 70 m2 / g or less.

[0019] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the porous carbon additive is 1.0 ㎛ to 4.0 ㎛.

[0020] The present invention also provides a positive electrode for an all-solid-state battery, wherein the bulk density of the porous carbon additive is 0.18 g / cc or more.

[0021] The present invention also provides a positive electrode for an all-solid-state battery, wherein the powder resistance of the porous carbon additive is 0.05 ohm·cm or less.

[0022] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the positive electrode active material is 3.0 ㎛ to 8.0 ㎛.

[0023] The present invention also provides a positive electrode for an all-solid-state battery, wherein the particle size (D50) of the sulfide-based solid electrolyte is 0.1 ㎛ to 1.5 ㎛.

[0024] The present invention also provides a positive electrode for an all-solid-state battery, wherein the positive electrode is in the form of a pellet including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

[0025] The present invention also comprises: the positive electrode, a positive electrode current collector; and a positive electrode active material layer formed on one surface of the positive electrode current collector;

[0026] The above-mentioned positive electrode active material layer provides a positive electrode for an all-solid-state battery, which includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

[0027] The present invention also provides a method for producing a composition comprising the binder comprising: polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, A positive electrode for an all-solid-state battery is provided, comprising at least one selected from the group consisting of polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene.

[0028] The present invention also provides an all-solid-state battery positive electrode, wherein the conductive material is at least one linear conductive material selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers (CNFs).

[0029] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is at least one selected from the group consisting of soft carbon and hard carbon.

[0030] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is at least one selected from the group consisting of activated carbon and carbon black.

[0031] The present invention also provides a positive electrode for an all-solid-state battery, wherein the porosity of the positive electrode is 5 vol% to 19 vol%.

[0032] The present invention also provides that the positive electrode active material is included in an amount of 55 to 90 wt% based on the total weight of the positive electrode,

[0033] The above sulfide-based solid electrolyte is included in an amount of 10 to 50 wt% based on the total weight of the positive electrode,

[0034] The above-mentioned conductive material is included in an amount of 0.05 to 10 wt% based on the total weight of the anode,

[0035] The present invention provides a positive electrode for an all-solid-state battery, wherein the porous carbon additive is included in an amount of 0.1 to 3 wt% based on the total weight of the positive electrode.

[0036]

[0037] The present invention also provides an all-solid-state battery comprising the positive electrode, the negative electrode, and the solid electrolyte membrane interposed therebetween.

[0038] According to the positive electrode for an all-solid-state battery of the present invention, the porous carbon additive fills the pores between the particles of the positive electrode active material and the sulfide-based solid electrolyte, thereby reducing the porosity of the positive electrode, thereby improving the energy density of the all-solid-state battery. Furthermore, by using a linear conductive material as the conductive material of the positive electrode for an all-solid-state battery, the conductivity of the positive electrode is maintained, thereby improving the energy density without reducing the performance of the all-solid-state battery.

[0039] Figure 1 is a scanning electron microscope photograph of the side surface of the anode prepared from the mixtures prepared in Example 2, Comparative Example 3, and Comparative Example 4.

[0040] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0041] The terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0042] In this specification, in order to distinguish between positive electrodes manufactured according to whether or not the positive electrode active material layer includes a binder, when the positive electrode does not include a binder, it may be referred to as a “composite positive electrode,” and when the positive electrode includes a binder, it may be referred to as a “positive electrode.”

[0043]

[0044] Cathode for all-solid-state batteries

[0045] The present invention relates to a positive electrode for an all-solid-state battery.

[0046] The positive electrode for an all-solid-state battery according to the present invention includes a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

[0047] In one embodiment of the present invention, the positive electrode may be in the form of a pellet. The positive electrode in the form of a pellet may be used in a current collector-free form, or the positive electrode may be formed by placing the pellet on the current collector. The pellet may be formed by pressing a composite powder including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive. Since the pellet does not include a binder, resistance that may be caused by the binder can be eliminated.

[0048] In another embodiment of the present invention, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on one surface of the positive electrode current collector. The positive electrode active material layer may include the positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

[0049] The particle size of the porous carbon additive may be between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte, and the porous carbon additive may have a BET specific surface area of ​​100 m2 / g or less. The conductive material may be a linear conductive material in consideration of the specific surface area. In the present specification, a positive electrode not including a binder may correspond to a composite positive electrode.

[0050] In the positive electrode for an all-solid-state battery according to the present invention, a gap is formed due to a difference in particle size between the positive electrode active material and the sulfide-based solid electrolyte, and the gap is filled with the porous carbon additive, so that the porosity of the positive electrode can be reduced and the energy density can be improved. Since the particle size (D50) of the porous carbon additive is larger than the particle size (D50) of the sulfide-based solid electrolyte and smaller than the particle size (D50) of the positive electrode active material, the gap can be filled with the porous carbon additive.

[0051]

[0052] In one embodiment of the present invention, the BET specific surface area of ​​the porous carbon additive may be 100 m2 / g or less. Specifically, the specific surface area of ​​the porous carbon additive may be 100 m2 / g or less, 90 m2 / g or less, 80 m2 / g or less, 70 m2 / g or less, 60 m2 / g or less, 50 m2 / g or less, 40 m2 / g or less, or 30 m2 / g or less. When the BET specific surface area exceeds 100 m2 / g, the contact interface between the porous carbon additive having a high specific surface area and the sulfide-based all-solid-state electrolyte for the positive electrode increases, thereby increasing the electrolyte decomposition reaction and decreasing the ionic conductivity of the positive electrode itself. In addition, the lower limit of the BET specific surface area is not particularly limited, but may be 5 m2 / g or more.

[0053] The above porous carbon additive has a low specific surface area as defined above and can be called macroporous carbon.

[0054] In addition, the particle size (D50) of the porous carbon additive may be 1.0 ㎛ to 4.0 ㎛. Specifically, the particle size (D50) of the porous carbon additive may be 1.0 ㎛ or more, 1.5 ㎛ or more, or 2.0 ㎛ or more, and 3.0 ㎛ or less, 3.5 ㎛ or less, or 4.0 ㎛ or less. If the particle size (D50) of the porous carbon additive is less than 1.0 ㎛, the particles are excessively small, so that rather than filling the pores formed by the difference in particle sizes between the particles of the positive active material and the sulfide-based solid electrolyte, the porous carbon additive may be adsorbed only on the surface of the positive active material, and if it exceeds 4.0 ㎛, it is difficult to fill the pores formed by the difference in particle sizes between the particles of the positive active material and the sulfide-based solid electrolyte, so that the effect of reducing the porosity of the positive electrode may be minimal.

[0055] The above particle size (D50) can be measured by adding a porous carbon additive to a particle size analyzer (Mastersizer 3000, Malvern).

[0056]

[0057] Additionally, the bulk density of the porous carbon additive may be 0.18 g / cc or more.

[0058] Specifically, the bulk density may be 0.18 g / cc or more, 0.19 g / cc or more, or 0.20 g / cc or more. If the bulk density is less than 0.18 g / cc, the density of the porous carbon additive itself may be low, which may reduce the overall density of the anode. The upper limit of the bulk density is not particularly limited, but may be 0.5 g / cc or less.

[0059] The above bulk density can be measured using a densitometer following the ASTM D 1895 method.

[0060]

[0061] Additionally, the powder resistivity of the porous carbon additive may be 0.05 ohm·cm or less.

[0062] Specifically, the powder resistance may be 0.05 ohm·cm or less, 0.04 ohm·cm or less, or 0.03 ohm·cm or less. If the powder resistance exceeds 0.05 ohm·cm, the resistance of the entire positive electrode may increase when the porous carbon additive in the positive electrode is contained at a certain fraction or more. The lower limit of the powder resistance is not particularly limited, but may be 0.005 ohm·cm or more. If the powder resistance becomes excessively small, electron transfer between the sulfide-based solid-state electrolyte in contact with the porous carbon additive may be active, and the sulfide-based solid-state electrolyte may exhibit a decomposition reaction.

[0063] The above powder resistance can be measured using a powder resistance meter (HPRM-FA2, Hantech). After attaching the lower punch to the body of the powder resistance mold, a conductive material sample of known weight is weighed, the upper punch is attached, and the sample is placed in the powder resistance meter. Afterwards, the powder resistance meter is operated to apply pressure from 0 to 2000 kgf in 400 kgf increments, and the final powder resistance can be observed at 2000 kgf (196 MPa).

[0064]

[0065] In addition, the porous carbon additive may include at least one selected from the group consisting of soft carbon and hard carbon, but is not limited thereto if the carbon material is in particle form. For example, the porous carbon additive may be at least one selected from activated carbon and carbon black.

[0066] In addition, the porous carbon additive may be included in an amount of 0.1 to 3 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the porous carbon additive may be 0.1 wt%, 0.2 wt% or more, 0.3 wt% or more, 0.4 wt% or more, or 0.5 wt% or more, and may be 1.2 wt% or less, 1.5 wt% or less, 2.0 wt% or less, 2.5 wt% or less, or 3.0 wt% or less. If the content of the porous carbon additive is less than 0.1 wt%, the effect of improving energy density due to the reduced porosity caused by the use of the porous carbon additive may be minimal, and if it exceeds 3 wt%, the mass transfer resistance may increase.

[0067]

[0068] In one embodiment of the present invention, the particle size (D50) of the positive electrode active material may be 3.0 ㎛ to 8.0 ㎛.

[0069] Specifically, the particle size (D50) of the positive electrode active material may be 3.0 ㎛ or more, 3.5 ㎛ or more, or 4.0 ㎛ or more, and may be 6.0 ㎛ or less, 6.5 ㎛ or less, 7.0 ㎛ or less, 7.5 ㎛ or less, or 8.0 ㎛ or less. If the particle size (D50) of the positive electrode active material is less than 3.0 ㎛, even if the positive electrode active material and the all-solid electrolyte are dispersed at the same weight ratio, the particle size of the positive electrode active material may be small, which may reduce dispersibility, and if it exceeds 7.0 ㎛, excessively large pores may be formed within the positive electrode active material layer, which may reduce the performance of the all-solid-state battery.

[0070] The above particle size (D50) can be measured by putting the positive electrode active material powder into a particle size analyzer (Mastersizer 3000, Malvern).

[0071] In addition, the positive electrode active material is not particularly limited as long as it is a material capable of reversibly absorbing and releasing lithium ions, and examples thereof include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), and Li[Ni x Co y Mn z M v ]O2 (wherein M is one or two or more elements selected from the group consisting of Al, Ga, and In; 0.3≤x<1.0, 0≤y, z≤0.5, 0≤v≤0.1, x+y+z+v=1), Li(Li a M b-a-b' M' b' )O 2-c A c(In the above formula, 0≤a≤0.2, 0.6≤b≤1, 0≤b'≤0.2, 0≤c≤0.2; M includes at least one selected from the group consisting of Mn and Ni, Co, Fe, Cr, V, Cu, Zn and Ti; M' is at least one selected from the group consisting of Al, Mg and B, and A is at least one selected from the group consisting of P, F, S and N.) layered compounds or compounds substituted with one or more transition metals; chemical formula Li 1+y Mn 2-y Lithium manganese oxides such as O4 (where y is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiFe3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-y Ni-site type lithium nickel oxide represented by MyO2 (wherein, M=Co, Mn, Al, Cu, Fe, Mg, B or Ga, and y is 0.01 to 0.3); chemical formula LiMn 2-y M y Lithium manganese composite oxides represented by O2 (wherein M is Co, Ni, Fe, Cr, Zn or Ta, and y is 0.01 to 0.1) or Li2Mn3MO8 (wherein M is Fe, Co, Ni, Cu or Zn); LiMn2O4 in which a portion of Li in the chemical formula is replaced by an alkaline earth metal ion; disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0072] In addition, the positive electrode active material may be included in an amount of 55 to 90 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the positive electrode active material may be 55 wt%, 60 wt% or more, or 65 wt% or more, and may be 83 wt% or less, 85 wt% or less, or 90 wt% or less. If the content of the positive electrode active material is less than 55 wt%, battery performance may deteriorate, and if it is more than 90 wt%, mass transfer resistance may increase.

[0073]

[0074] In one embodiment of the present invention, the particle size (D50) of the sulfide-based solid electrolyte may be 0.1 ㎛ to 1.5 ㎛.

[0075] Specifically, the particle size (D50) of the sulfide-based solid electrolyte may be 0.1 ㎛ or more, 0.3 ㎛ or more, or 0.5 ㎛ or more, and may be 0.9 ㎛ or less, 1.0 ㎛ or less, 1.2 ㎛ or less, or 1.5 ㎛ or less. If the particle size (D50) of the sulfide-based solid electrolyte is less than 0.1 ㎛, the ultrafine particles of the all-solid electrolyte may not be sufficiently dispersed within the positive electrode layer and may aggregate, and if it exceeds 1.5 ㎛, dispersion may be somewhat easy, but the contact surface with the positive electrode active material particles may decrease and the positive electrode porosity may increase.

[0076] In addition, the sulfide-based solid electrolyte may include at least one selected from the group consisting of LiPSX (X = Cl, Br or I), LiGePS, and LiPS. However, the sulfide-based solid electrolyte is not limited to these, and a sulfide-based solid electrolyte commonly used in the art can be widely used.

[0077] In addition, the sulfide-based solid electrolyte may be included in an amount of 10 to 50 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the sulfide-based solid electrolyte may be 10 wt% or more, 20 wt% or more, or 30 wt% or more, and may be 40 wt% or less, 45 wt% or less, or 50 wt% or less. If the content of the positive electrode active material is less than 10 wt%, it may not be sufficient to fill the pores formed in the positive electrode active material layer, making it difficult to reduce the porosity of the positive electrode active material. If it exceeds 50 wt%, the content of the positive electrode active material and the conductive material may be relatively reduced, resulting in deterioration in battery performance.

[0078]

[0079] In one embodiment of the present invention, the conductive material may be a linear conductive material, and the linear conductive material may be at least one selected from the group consisting of carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The linear conductive material may improve electrical conductivity due to its morphological characteristics.

[0080] In addition, the conductive material may be included in an amount of 0.05 to 10 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the conductive material may be 0.05 wt% or more, 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 2 wt% or more, or 3 wt% or more, and may be 5 wt% or less, 7 wt% or less, or 10 wt% or less. If the content of the conductive material is less than 0.05 wt%, the electrical conductivity of the positive electrode may be reduced, and if it exceeds 10 wt%, the content of the positive electrode active material and the sulfide-based solid electrolyte may be relatively reduced, thereby deteriorating battery performance.

[0081]

[0082] In one embodiment of the present invention, the positive electrode active material layer may further include a binder. The binder may be included to facilitate bonding between materials included in the positive electrode active material layer and between the positive electrode active material layer and the positive electrode current collector. The binder may promote bonding between materials included in the positive electrode active material layer, thereby further reducing the positive electrode porosity.

[0083] The above binder may be a fibrous binder. During the mixing process of manufacturing the positive electrode, the binder may undergo fiberization and be incorporated into the positive electrode active material layer in a fibrous form. Therefore, it is preferable that the binder have physical properties that can be easily modified.

[0084] In addition, the binder is polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, It may include at least one selected from the group consisting of polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0085] In addition, the binder may be included in an amount of 0.1 to 3 wt% based on the total weight of the positive electrode active material layer. Specifically, the content of the binder may be 0.1 wt% or more, 0.5 wt% or more, or 0.8 wt% or more, and may be 1.5 wt% or less, 2 wt% or less, or 3 wt% or less. If the content of the binder is less than 0.1 wt%, the effect of improving the bonding strength between materials included in the positive electrode active material layer may be minimal, and thus the electrode sheet may not be properly formed. If the content of the binder is more than 3 wt%, ionic conductivity or electrical conductivity may be reduced.

[0086]

[0087] In one embodiment of the present invention, the porosity of the positive electrode active material layer may be 5 vol% to 19 vol%.

[0088] Specifically, the porosity may be 5 vol% or more, 8 vol% or more, 10 vol% or more, or 13 vol% or more, and 17 vol% or less, 18 vol% or less, or 19 vol% or less. The porosity is an optimized range considering performance such as the energy density of the battery, and if the porosity exceeds 19 vol%, the energy density of the battery may decrease.

[0089]

[0090] In one embodiment of the present invention, the thickness of the positive electrode active material layer may be 100 μm to 300 μm, and specifically, may be 100 μm or more, 110 μm or more, or 120 μm or more, and may be 200 μm or less, 250 μm or less, or 300 μm or less. However, the thickness of the positive electrode active material layer is not limited thereto, and the thickness may be adjusted to have an appropriate positive electrode loading according to the improvement in the performance of various positive electrode elements included in the positive electrode active material layer.

[0091]

[0092] In one embodiment of the present invention, the positive electrode current collector supports the positive electrode active material layer and serves to transfer electrons between the external conductor and the positive electrode active material layer.

[0093] The positive electrode current collector is not particularly limited as long as it has high electronic conductivity without causing chemical changes in the all-solid-state battery. For example, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, stainless steel surface-treated with carbon, nickel, silver, etc., aluminum-cadmium alloy, etc. can be used as the positive electrode current collector.

[0094] The positive electrode current collector may have a finely irregular structure on its surface or may employ a three-dimensional porous structure to strengthen the bonding strength with the positive electrode active material layer. Accordingly, the positive electrode current collector may include various forms such as a film, sheet, foil, mesh, net, porous body, foam, or non-woven fabric.

[0095]

[0096] Method for manufacturing a cathode for an all-solid-state battery

[0097] The present invention also relates to a method for manufacturing a positive electrode for an all-solid-state battery. The specific materials, properties, and contents of the positive electrode active material, sulfide-based solid electrolyte, conductive agent, porous carbon additive, and binder used in the method for manufacturing a positive electrode for an all-solid-state battery according to the present invention are as described above.

[0098] In the present invention, the positive electrode may be referred to as a “composite positive electrode” when it does not contain a binder, or as a “positive electrode” when it contains a binder, depending on whether or not it contains a binder.

[0099] In one embodiment of the present invention, a method for manufacturing a composite positive electrode not including a binder may include: (A1) a step of mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive; and (A2) a step of manufacturing the mixed powder obtained in step (A1) into a pellet form. At this time, the pellet form in step (A2) may be formed by pressing with a jig.

[0100] The composite anode manufactured as described above can be applied to a pressure jig cell. Since the composite anode does not contain a binder, the binder's resistance factor can be eliminated. Therefore, the composite anode can be used to conduct performance evaluations using a pressure jig cell, eliminating the resistance factor.

[0101]

[0102] In addition, in one embodiment of the present invention, a method for manufacturing a positive electrode including a binder includes: (B1) a step of mixing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive binder; (B2) a step of applying the mixed powder obtained in step (B1) to a calendaring process to form it into a film shape; and (B3) a step of attaching a positive electrode active material layer in a film shape obtained in step (B2) to a positive electrode current collector.

[0103] The mixing in step (B1) above may be physical mixing, and the physical mixing may cause the binder to be fiberized. During the physical mixing, the binder may be physically deformed by friction with the particles in the mixed powder due to shear force, thereby causing fiberization. For example, PTFE, which has properties that facilitate physical deformation, may be used as the binder. Furthermore, to facilitate physical deformation, the mixing may be performed by introducing an induction heating device, ball milling, or roll pressing.

[0104]

[0105] Additionally, in the above step (B2), the mixed powder obtained in the above step (B1) can be formed into a film shape by applying a calendaring process.

[0106] The conditions for the above-mentioned calendering process may be applied by appropriately controlling process conditions that can be formed into a film form. For example, the calendering process may be performed at a temperature of 50°C to 200°C for 5 to 50 loops. However, any of the calendering process conditions, such as temperature, pressure, and number of loops, that are used in electrode manufacturing processes commonly used in the battery field may be used.

[0107]

[0108] In addition, in the step (B3), a film-shaped positive electrode active material layer obtained in the step (B2) can be attached to a positive electrode current collector to manufacture a positive electrode for an all-solid-state battery.

[0109]

[0110] All-solid-state batteries

[0111] The present invention also relates to an all-solid-state battery including the solid electrolyte membrane.

[0112] The all-solid-state battery according to the present invention comprises the positive electrode, the negative electrode, and a sulfide-based solid electrolyte layer interposed therebetween. The positive electrode is as described above.

[0113]

[0114] In one embodiment of the present invention, the negative electrode includes a negative electrode active material layer, and the negative electrode active material layer may be formed on one surface of a negative electrode current collector.

[0115] The above negative active material layer may include a negative active material, a conductive material, and a binder. Alternatively, the negative active material layer may be an anodeless layer.

[0116]

[0117] In the above negative electrode active material layer, the negative electrode active material is lithium (Li + ) can be reversibly intercalated or deintercalated, a material that can react with lithium ions to form a reversibly lithium-containing compound, or a lithium metal or a lithium alloy.

[0118] The above lithium ion (Li + ) can be reversibly inserted or de-inserted, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The lithium ion (Li + ) can be, for example, tin oxide, titanium nitrate or silicon. The lithium alloy can be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al) and tin (Sn).

[0119] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In), and specifically, may be in the form of a lithium metal or lithium and a thin film or a lithium-indium alloy thin film or powder.

[0120] The negative electrode active material may be included in an amount of 40 to 80 wt% based on the total weight of the negative electrode active material layer. Specifically, the content of the negative electrode active material may be 40 wt% or more or 50 wt% or more, and 70 wt% or less or 80 wt% or less. If the content of the negative electrode active material is less than 40 wt%, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if it exceeds 80 wt%, the material transfer resistance may increase.

[0121] In addition, the binder is a component that assists in the bonding of the negative electrode active material and the conductive material and the bonding to the negative electrode current collector, and includes styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile butadiene rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluorine rubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose It may include at least one selected from the group consisting of acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethylsucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0122] In addition, the binder may be included in an amount of 0.5 wt% to 4 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, or 1.5 wt% or more, and 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the content of the binder is less than 0.5 wt%, the adhesive strength between the positive electrode active material and the negative electrode current collector may be reduced, and if it exceeds 4 wt%, the adhesive strength may be improved, but the content of the negative electrode active material may be reduced, which may lower the battery capacity.

[0123]

[0124] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery, does not cause chemical changes in the battery, and has excellent electrical conductivity. Representative examples thereof include graphite or conductive carbon, and examples thereof include graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black, and summer black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fiber and metal fiber; fluorinated carbon; metal powder such as aluminum powder and nickel powder; conductive whiskey such as zinc oxide and potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives; which may be used alone or in combination of two or more thereof, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0125] The conductive material may typically be included in an amount of 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too low, such as less than 1 wt%, it may be difficult to expect an effect of improving electrical conductivity or the electrochemical characteristics of the battery may deteriorate, and if it exceeds 5 wt%, the amount of the negative electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the negative electrode is not particularly limited, and conventional methods known in the art, such as mixing with the negative electrode active material or coating, may be used.

[0126] In addition, the negative electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. In addition, the negative electrode current collector, like the positive electrode current collector, may be made of various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc. having fine irregularities formed on the surface.

[0127] The method for manufacturing the above negative electrode is not particularly limited, and can be manufactured by forming a negative electrode active material layer on the negative electrode current collector using a method for forming a layer or film commonly used in the art. For example, methods such as compression, coating, and deposition can be used. In addition, a case in which a battery is assembled on the negative electrode current collector without a lithium thin film and then a metallic lithium thin film is formed on the metal plate through initial charging is also included in the negative electrode of the present invention.

[0128]

[0129] In addition, the above-mentioned non-cathode layer refers to a cathode layer in which lithium metal or lithium alloy, which can be a lithium source among the cathode active materials, does not exist in the cathode when the battery is first assembled, and lithium is deposited in the cathode through charging. A battery including the above-mentioned non-cathode layer can be referred to as a cathode-free battery.

[0130] In the above negative electrode-free battery, while the battery is being charged and discharged, lithium ions released from the positive electrode move to the negative electrode to form a negative electrode active material layer. For example, when the battery is being charged, lithium ions are desorbed from the positive electrode active material and move to the negative electrode, forming a lithium metal layer in the form of a layer on the negative electrode current collector, which is purely composed of lithium, or a lithium metal structure in an arbitrary form other than a layer form can be formed. The arbitrary form can be, for example, a structure in which lithium metal is aggregated in the form of particles.

[0131]

[0132] In one embodiment of the present invention, the sulfide-based solid electrolyte included in the sulfide-based solid electrolyte layer may include at least one selected from the group consisting of LiPSX (X = Cl, Br or I), LiGePS, and LiPS. However, the sulfide-based solid electrolyte is not limited to these, and a sulfide-based solid electrolyte commonly used in the art can be widely used.

[0133]

[0134] battery module

[0135] The present invention also relates to a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0136] Hereinafter, specific examples of the device include, but are not limited to, a power tool that is powered by an electric motor; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); an electric two-wheeled vehicle including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; and a power storage system. Hereinafter, preferred embodiments are presented to help understand the present invention, but the following embodiments are only illustrative of the present invention and it will be apparent to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it will be apparent that such changes and modifications also fall within the scope of the appended patent claims.

[0137] Hereinafter, preferred examples are presented to help understand the present invention, but the following examples are only illustrative of the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is also natural that such changes and modifications fall within the scope of the appended patent claims.

[0138] In the following examples and comparative examples, a positive electrode and an all-solid-state battery including the same were manufactured according to the composition of the positive electrode active material layer and the properties of the raw materials as described in Table 1 below.

[0139]

[0140] Composition of the positive electrode active material layer (wt%) Properties of raw materials Porous carbon additive Positive electrode active material Sulfide-based solid electrolyte Positive electrode active material Sulfide-based solid electrolyte Conductive material Porous carbon additive Binder BET specific surface area (㎡ / g) Particle size (D50) (㎛) Particle size (D50) (㎛) Particle size (D50) (㎛) Example 1603541-60 ㎡ / g or less 1.7 주1)5.30.8 Example 283150.80.2160 ㎡ / g or less 1.7 주1) 5.30.8 Comparative Example 160355----5.30.8 Comparative Example 2603541-500 ㎡ / g or more 1.7 주3) 5.30.8 Comparative Example 383151-1--5.30.8 Comparative Example 483150.8 0.2 160 ㎡ / g or less 1.0 주2) 5.30.8 Note 1) The porous carbon additive used in Examples 1 and 2 is referred to as “low specific surface area porous additive 1.” Note 2) The porous carbon additive used in Comparative Example 4 has a smaller particle size than the low specific surface area porous additive 1, and is referred to as “low specific surface area porous additive 2” for distinction. Note 3) The porous carbon additive used in Comparative Example 2 is referred to as “high specific surface area porous additive.”

[0141]

[0142] Example 1: Preparation of composite anode

[0143] LiN as a cathode active material 0.8 Co 0.1 Mn 0.1 A cathode was manufactured as follows using O2 (NCM 811), Li6PS5Cl as a sulfide-based solid electrolyte, carbon nanofibers (CNF) as a linear conductive material, and a porous carbon additive (Heraeus, BET 60 m2 / g or less) as a conductive material. Hereinafter, the porous carbon additive is referred to as low surface area porous carbon additive 1.

[0144] Powder mixing was performed with a weight ratio of 60:35:4:1 for the positive electrode active material, sulfide-based solid electrolyte, conductive agent, and porous carbon additive. Specifically, the positive electrode active material and sulfide-based solid electrolyte were quantified in powder form and mixed for 15 minutes using an agate mortar in a dry room environment to obtain a mixture. Thereafter, the conductive agent and porous carbon additive were quantified and added to the mixture, and then mixed for an additional 15 minutes to obtain a mixed powder.

[0145] The above mixed powder was pressurized using a pressurizing jig to produce a composite positive electrode in the form of a pellet with a loading of 3 mAh / cm2.

[0146]

[0147] Example 2: Anode fabrication

[0148] LiN as a cathode active material 0.8 Co 0.1 Mn 0.1 The positive electrode was manufactured as follows using O2 (NCM 811), Li6PS5Cl as a sulfide-based solid electrolyte, CNF as a linear conductive material, low surface area porous carbon additive 1 (Heraeus, BET 60 ㎡ / g or less) as a porous carbon additive, and polytetrafluoroethylene (PTFE) as a binder.

[0149] A powder mixing was performed with a positive electrode active material, a sulfide-based solid electrolyte, a conductive agent, a porous carbon additive, and a binder in a weight ratio of 83:15:0.8:0.2:1. Specifically, the positive electrode active material and the sulfide-based solid electrolyte were quantified in powder form and mixed for 15 minutes using a blade mixer in a dry room environment to obtain a mixture. Thereafter, the conductive agent and low-porous carbon additive 1 were quantified and added to the mixture, followed by mixing. The binder PTFE (Polytetrafluoroethylene) powder was quantified and further mixed to obtain a mixed powder.

[0150] After the above mixed powder was injected into the inducer, fiberization was performed in the inducer, and calendaring was performed on a roller to manufacture a positive electrode having a thickness of 150 μm.

[0151]

[0152] Comparative Example 1

[0153] A composite anode was prepared in the same manner as in Example 1, except that no porous carbon additive was used.

[0154]

[0155] Comparative Example 2

[0156] A composite anode was manufactured in the same manner as in Example 1, except that a high specific surface area porous carbon additive (Heraeus, BET 500 m2 / g or more) was used instead of the low specific surface area porous carbon additive 1 as the porous carbon additive.

[0157]

[0158] Comparative Example 3

[0159] A positive electrode was manufactured in the same manner as in Example 2, except that no porous carbon additive was used.

[0160]

[0161] Comparative Example 4

[0162] A positive electrode was manufactured in the same manner as in Example 2, except that a porous carbon additive (Heraeus, BET 60 m2 / g or less) having a smaller particle size than the porous carbon additive (low specific surface area porous additive 1) used in Example 2 was used. Hereinafter, the porous carbon additive having a smaller particle size than the low specific surface area porous additive 1 is referred to as low specific surface area porous carbon additive 2.

[0163]

[0164] Experimental Example 1: Performance Evaluation of All-Solid-State Battery

[0165] The performance of an all-solid-state battery was evaluated according to the inclusion of a porous carbon additive in the positive electrode active material layer and the specific surface area of ​​the porous carbon additive. The composite positive electrodes manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were evaluated.

[0166] To evaluate the performance of the above all-solid-state battery, a pressure jig cell was manufactured using the following method.

[0167] After transferring the composite anode in the form of a pellet to a pressure jig cell, a sulfide-based solid electrolyte powder (200 mg) was placed on the pellet, and pressurized with a force of 400 Mpa for 60 seconds to form a membrane-like sulfide-based solid electrolyte layer. Thereafter, a lithium metal negative electrode was placed facing one side of the sulfide-based solid electrolyte layer, and pressurized again with a force of 100 Mpa to increase the contact between the sulfide-based solid electrolyte layer and the negative electrode. Thereafter, the pressure jig cell was manufactured by fastening with an appropriate pressure.

[0168] The capacity capability was observed through a protocol in which the pressure jig cell was activated in a charger / discharger at 0.05 C for 2 cycles and then discharged up to 1 C, and the results are shown in Tables 2 and 3 below. Specifically, the capacity capability was observed through a protocol in which 0.05 C CC / CV (Constant Current / Constant Voltage) charging, 0.05 C CC (Constant Current) discharge 2 cycles, and then 0.1 C CC / CV charging was maintained, but CC discharge was performed at 0.1 C / 0.2 C / 0.33 C / 0.5 C / 1 C.

[0169]

[0170] Voltage range / temperature 3.0 ~ 4.25 V / 60℃Distinction Example 1Comparative Example 1Comparative Example 2Loading (mAh / ㎠)31 st Charging capacity (0.05C) mAh / g 228.1215.3221.71 st Discharge capacity (0.05C) 210.2201.2205.7 Efficiency % 92.193.492.82 nd Charging capacity (0.05C) mAh / g 216.2206.8211.52 ndDischarge capacity (0.05C) 209.1 199.6 204.4 Efficiency % 96.7 96.8 96.7

[0171]

[0172] Referring to Table 2 above, Example 1 and Comparative Example 1 are cases where the low specific surface area porous carbon additive 1 was included and not included, respectively, and it was confirmed that Example 1 showed superior performance in terms of discharge capacity compared to Comparative Example 1 after performing formation for 2 cycles. In addition, Example 1 and Comparative Example 2 are cases where the low specific surface area porous carbon additive 1 and the high specific surface area porous carbon additive were included, respectively, and it was found that in the case of Comparative Example 2, the initial efficiency was at the same level as Comparative Example 1, but the discharge capacity was somewhat inferior.

[0173]

[0174] mAh (%)Example 1Comparative Example 1Comparative Example 2Rate (0.1C charge)0.1C206.6195.82090.2C203.3192205.50.33C199.8187.5202.10.5C194.9180.6195.31.0C185.4169.5163.2

[0175] Referring to Table 3 above, it was confirmed that Example 1 had a superior discharge capacity retention rate compared to Comparative Examples 1 and 2. Specifically, Example 1 maintained a discharge capacity of 185 mAh / g even at 1C discharge, while Comparative Examples 1 and 2 measured discharge capacities of 170 mAh / g or less. This is due to the phenomenon that, when the specific surface area of ​​the porous carbon additive in the composite positive electrode is high (Comparative Example 2), the decomposition reaction of the sulfide-based solid electrolyte in contact with the porous carbon additive is accelerated as the c-rate increases. In addition, when the porous carbon additive is not included in the positive electrode (Comparative Example 1), although a conductive network is sufficiently formed due to the use of a linear conductive material, the porosity of the composite positive electrode in the pressure jig cell may be higher than that of the positive electrode using the porous carbon additive, and accordingly, the lithium ion conductivity may decrease, which may infer that the discharge capacity retention rate may decrease.

[0176]

[0177] Experimental Example 2: Confirming the Internal Structure of the Anode

[0178] An experiment was conducted to measure the internal structure and electrical conductivity of a positive electrode according to the presence or absence of a porous carbon additive in a positive electrode active material layer including a binder and the particle size of the porous carbon additive. Example 2, Comparative Examples 3 and 4 were evaluated. All of these examples include a binder in the positive electrode active material layer.

[0179] The positive electrodes manufactured according to Example 2, Comparative Example 3, and Comparative Example 4 were further pressurized using WIP (Warm Isostatic Press) to form a completely adhered form of the positive electrode elements, and then the side surfaces of the positive electrodes were observed using a scanning electron microscope (SEM). Example 2, Comparative Example 3, and Comparative Example 4 all use a binder in the manufacture of the positive electrodes. Example 2 includes a low-surface-area porous carbon additive 1, Comparative Example 3 does not include a porous carbon additive, and Comparative Example 4 includes a low-surface-area porous carbon additive 2 having a smaller particle size than Example 2.

[0180]

[0181] Figure 1 is a scanning electron microscope photograph of the side surface of an anode manufactured using the anode materials of Example 2, Comparative Example 3, and Comparative Example 4.

[0182] Referring to FIG. 1, it was found that the dispersibility of the constituent materials included in the positive electrode active material layer was not particularly reduced in Example 2 and Comparative Example 4, which included a porous carbon additive, compared to Comparative Example 3, which did not include a porous carbon additive.

[0183]

[0184] In addition, the porosity before and after the WIP rolling was measured, and the electrical conductivity was measured using the manufactured positive electrode, and the results are shown in Table 4 below. At this time, the porosity was measured using the positive electrode density calculated from 1) the thickness of the positive electrode after WIP rolling, 2) the weight of the positive electrode, 3) the area of ​​the positive electrode, and 4) the true density of the positive electrode element used, according to the following mathematical formula 1.

[0185]

[0186] [Mathematical Formula 1]

[0187] Anode porosity (%) = (1-([Anode weight] / [Anode area x Anode thickness] / [Anode density] x 100)

[0188]

[0189] In addition, the electrical conductivity (S / cm) was measured by reciprocally calculating the resistance value (ohmㆍcm) obtained by placing an electrically conductive Al foil on one side of the anode after manufacturing it and pressing it with WIP to make an electrode for measuring electrical conductivity, and then placing it against the multi probe of an electrode resistance measurement system (RM2610, Hioki). The average value was recorded after three measurements.

[0190]

[0191] Example 2 Comparative Example 3 Comparative Example 4 Porosity (vol%) after rolling 1619.220.5 Electrical conductivity (S / cm) 5.9.E-05 5.0.E-05 4.7.E-05

[0192]

[0193] Referring to Table 4 above, the porosity of the anode of Example 2 including the low surface area porous carbon additive 1 was reduced by approximately 3 vol% compared to before rolling, compared to Comparative Example 3 not including the porous carbon additive. In addition, the electrical conductivity measured using the anode of Example 2 was also confirmed to be greater than those of Comparative Examples 3 and 4.

[0194] It was confirmed that the anode of Comparative Example 4, which included low surface area porous carbon additive 2 having a smaller particle size than low surface area porous carbon additive 1 of Example 2, had increased porosity after rolling and had the lowest electrical conductivity.

[0195] The low surface area porous carbon additive 1 (D50 1.7 ㎛) used in Example 2 has a particle size between that of the positive electrode active material (D50 5 ㎛) and the sulfide-based solid electrolyte (D50 0.7 ㎛). The low surface area porous carbon additive 2 used in Comparative Example 4 has a smaller particle size than the low surface area porous carbon additive 1 of Example 2, and thus it was expected to more effectively fill the pores formed by the positive electrode active material and the sulfide-based solid electrolyte. However, it was confirmed that, due to the very low particle size and the resulting fine particles, it was adsorbed only on the surface of the positive electrode active material and did not reduce the porosity of the entire positive electrode active material layer.

[0196] Therefore, it can be predicted that the porosity of the positive electrode active material layer will be reduced due to the low surface area porous carbon additive 1 used in Example 2, and thus the performance of the positive electrode will be increased.

Claims

1. A positive electrode for an all-solid-state battery comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive, The particle size of the above porous carbon additive is between the particle size of the positive electrode active material and the particle size of the sulfide-based solid electrolyte, A positive electrode for an all-solid-state battery, wherein the above porous carbon additive is a low-surface-area porous carbon additive having a BET surface area of ​​100 m2 / g or less.

2. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the BET specific surface area of ​​the above porous carbon additive is 70 m2 / g or less.

3. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the particle size (D50) of the porous carbon additive is 1.0 ㎛ to 4.0 ㎛.

4. In paragraph 1, A cathode for an all-solid-state battery, wherein the bulk density of the porous carbon additive is 0.18 g / cc or more.

5. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the powder resistance of the above porous carbon additive is 0.05 ohm·cm or less.

6. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the particle size (D50) of the positive electrode active material is 3.0 ㎛ to 8.0 ㎛.

7. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the particle size (D50) of the above sulfide-based solid electrolyte is 0.1 ㎛ to 1.5 ㎛.

8. In paragraph 1, An all-solid-state battery positive electrode, wherein the positive electrode is in the form of a pellet containing a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a porous carbon additive.

9. In paragraph 1, The above positive electrode includes a positive electrode current collector; and a positive electrode active material layer formed on one surface of the positive electrode current collector, An all-solid-state battery positive electrode, wherein the positive electrode active material layer comprises a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, a binder, and a porous carbon additive.

10. In paragraph 9, The above binder is polytetrafluoroethylene (PTFE), polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, polyethylene oxide, chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenol resin, epoxy resin, carboxymethylcellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylcellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, An all-solid-state battery positive electrode comprising at least one selected from the group consisting of polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropene.

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

12. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the porous carbon additive is at least one selected from the group consisting of soft carbon and hard carbon.

13. In paragraph 1, An all-solid-state battery positive electrode, wherein the porous carbon additive is at least one selected from the group consisting of activated carbon and carbon black.

14. In paragraph 1, A positive electrode for an all-solid-state battery, wherein the porosity of the positive electrode is 5 vol% to 19 vol%.

15. In paragraph 1, The positive electrode active material is included in an amount of 55 to 90 wt% based on the total weight of the positive electrode, The above sulfide-based solid electrolyte is included in an amount of 10 to 50 wt% based on the total weight of the positive electrode, The above-mentioned conductive material is included in an amount of 0.05 to 10 wt% based on the total weight of the anode, A positive electrode for an all-solid-state battery, wherein the porous carbon additive is contained in an amount of 0.1 to 3 wt% based on the total weight of the positive electrode.

16. An all-solid-state battery comprising the positive electrode, negative electrode and a sulfide-based solid electrolyte layer interposed therebetween.

Images