Negative electrode for all-solid-state battery and all-solid-state battery including same

Abstract

The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery including same. More specifically, by introducing a porous carbon layer to a graphite-containing negative electrode for an all-solid-state battery to facilitate the movement of lithium ions, the ionic conductivity of the negative electrode for an all-solid-state battery can be improved.

Description

Anode for an all-solid-state battery and an all-solid-state battery comprising the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0078677, filed June 18, 2024, and Korean Patent Application No. 10-2025-0076835, filed June 12, 2025, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery including the same.

[0005] Graphite has been used in lithium-ion batteries (LIBs) as a stable, high-rate rechargeable cathode material.

[0006] In batteries using existing liquid electrolytes, the liquid electrolyte can easily penetrate into the negative electrode containing graphite, so lithium ions can be easily transferred between the graphite inside the negative electrode, and thus ion conductivity inside the negative electrode is excellent.

[0007] However, since all-solid-state batteries, which have recently seen increasing demand, use solid electrolytes, there is a problem in that it is not easy to secure ion conductivity inside the cathode as when using liquid electrolytes.

[0008] To address these issues, a technology has been developed to secure ionic conductivity within the anode by introducing a solid electrolyte material into the graphite-containing anode in an all-solid-state battery and utilizing the solid electrolyte as a lithium ion path. However, introducing a solid electrolyte material into the graphite-containing anode complicates the process and lowers the energy density of the battery. Furthermore, because the solid electrolyte is utilized as a lithium ion path, it is not easy to secure ionic conductivity comparable to that of batteries using conventional liquid electrolytes. Furthermore, side reactions may occur between the solid electrolyte and graphite, which may increase resistance.

[0009] Accordingly, in order to use graphite as an anode material for all-solid-state batteries, it is necessary to develop a technology that can prevent an increase in resistance within the anode while simultaneously increasing the ionic conductivity of the anode.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Chinese Patent Publication No. 117691060

[0013] The inventors of the present invention have conducted multifaceted research to solve the above problems and have confirmed that by introducing a porous carbon layer into an all-solid-state battery negative electrode including graphite, the movement of lithium ions can be facilitated, thereby preventing an increase in resistance of the all-solid-state battery negative electrode and improving ionic conductivity.

[0014] Accordingly, an object of the present invention is to provide a negative electrode for an all-solid-state battery in which an increase in resistance is prevented while ionic conductivity is improved.

[0015] In addition, another object of the present invention is to provide an all-solid-state battery including an all-solid-state battery negative electrode in which the increase in resistance is prevented and ionic conductivity is improved.

[0016] In order to achieve the above purpose, the present invention,

[0017] negative current collector;

[0018] A negative electrode active material layer formed on one surface of the negative electrode current collector and including graphite; and

[0019] Provided is an anode for an all-solid-state battery including a porous carbon layer formed on one surface of the anode active material layer.

[0020] In one embodiment of the present invention, an anode for an all-solid-state battery is provided, wherein the porosity of the porous carbon layer is 30% to 60%.

[0021] In one embodiment of the present invention, an anode for an all-solid-state battery is provided, wherein the thickness of the porous carbon layer is greater than 0 μm and less than or equal to 10 μm.

[0022] In one embodiment of the present invention, an anode for an all-solid-state battery is provided, wherein the porous carbon layer includes at least one type of carbon black selected from the group consisting of thermal black, acetylene black, and ketjen black.

[0023] In one embodiment of the present invention, an all-solid-state battery negative electrode is provided, wherein the negative electrode active material layer further includes a binder.

[0024] In one embodiment of the present invention, an anode for an all-solid-state battery is provided, wherein the binder includes at least one selected from the group consisting of polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), and carboxymethyl cellulose (CMC).

[0025] In one embodiment of the present invention, an all-solid-state battery negative electrode is provided, wherein the binder is included in an amount of 1 to 5 wt% based on the total weight of the negative electrode active material layer.

[0026] In one embodiment of the present invention, an all-solid-state battery negative electrode is provided, wherein the negative electrode active material layer is solid electrolyte-free (SE-free).

[0027] In one embodiment of the present invention, an anode for an all-solid-state battery is provided, wherein the anode current collector comprises stainless steel (SS), copper (Cu), nickel (Ni), or titanium (Ti).

[0028]

[0029] The present invention also provides an all-solid-state battery comprising: a positive electrode; the negative electrode; and a solid electrolyte membrane interposed between the positive electrode and the negative electrode.

[0030] In one embodiment of the present invention, an all-solid-state battery is provided, wherein the solid electrolyte membrane includes a sulfide-based solid electrolyte.

[0031] According to the present invention, by introducing a porous carbon layer into an all-solid-state battery negative electrode including graphite as a negative electrode active material, the movement of lithium ions is facilitated, thereby improving the ionic conductivity of the all-solid-state battery negative electrode.

[0032] In addition, since a separate material for use as a lithium ion transfer path is not introduced to improve the ion conductivity of the negative electrode for the above-mentioned all-solid-state battery, there is an effect of preventing an increase in resistance due to a side reaction between the negative electrode active material and the separate material for use as a lithium ion transfer path.

[0033] Figure 1 is a graph showing the capacity retention (cycle retention) according to the number of cycles of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Example 1.

[0034] Figure 2 is a graph showing the Coulomb efficiency according to the number of cycles of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Example 1.

[0035] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0036] 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.

[0037]

[0038] Cathode for all-solid-state batteries

[0039] The present invention relates to a negative electrode for an all-solid-state battery.

[0040] An anode for an all-solid-state battery according to the present invention comprises: a cathode current collector; a cathode active material layer formed on one surface of the cathode current collector and including graphite; and a porous carbon layer formed on one surface of the cathode active material layer.

[0041] In one embodiment of the present invention, the porosity of the porous carbon layer may be 30% to 60%.

[0042] The porous carbon layer can improve the ion conductivity of the negative electrode by increasing the oxygen saturation while the pores formed inside serve as a lithium ion transfer path.

[0043] In addition, if the porosity of the porous carbon layer is less than 30%, the degree of improvement in the ionic conductivity of the negative electrode may be minimal, and if it exceeds 60%, the mechanical properties of the negative electrode may deteriorate. Specifically, the porosity of the porous carbon layer may be 30% or more, 35% or more, or 40% or more, and may be 60% or less, 55% or less, or 50% or less.

[0044]

[0045] In one embodiment of the present invention, the thickness of the porous carbon layer may be greater than 0 μm and less than or equal to 10 μm.

[0046] If the thickness of the porous carbon layer is 0 ㎛, the effect of improving the ion conductivity of the negative electrode is minimal, and when applied to an all-solid-state battery, the life characteristics of the battery may deteriorate, and if it exceeds 10 ㎛, it may act as resistance within the battery due to the excessive thickness. Specifically, the thickness of the porous carbon layer may be more than 0 ㎛, 1 ㎛ or more, 2 ㎛ or more, or 3 ㎛ or more, and may be 10 ㎛ or less, 9 ㎛ or less, 8 ㎛ or less, 7 ㎛ or less, 6 ㎛ or less, or 5 ㎛ or less.

[0047]

[0048] In one embodiment of the present invention, the porous carbon layer may include at least one type of carbon black selected from the group consisting of thermal black, acetylene black, and ketjen black. However, the carbon that may be included in the porous carbon layer is not particularly limited as long as it has the characteristics of good ionic conductivity, low reactivity with lithium ions, and good ion permeability.

[0049] Additionally, the carbon may be doped with one or more elements selected from the group consisting of nitrogen, boron, and phosphorus. Due to the doped form of the carbon, the effect of improving ionic conductivity within the cathode may be further enhanced.

[0050]

[0051] In one embodiment of the present invention, the negative electrode active material layer may further include a binder. The binder may be included for bonding between negative electrode active materials and bonding between the negative electrode active material layer and the porous coating layer.

[0052] The above binder is not particularly limited as long as it can be used in an anode for an all-solid-state battery. For example, the binder may include at least one selected from the group consisting of polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), and carboxymethyl cellulose (CMC). In addition, the binder is selected from the group consisting of 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, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, It may further include at least one selected from the group consisting of cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, and polyurethane.

[0053] In addition, the binder may be included in an amount of 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. Specifically, the content of the binder may be 1 wt% or more, 1.5 wt% or more, or 2 wt% or more, and may be 5 wt% or less, 4.5 wt% or less, 4 wt% or less, 3.5 wt% or less, or 3 wt% or less. If the content of the binder is less than 1 wt%, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced, and if it exceeds 5 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.

[0054]

[0055] In one embodiment of the present invention, the negative electrode active material layer includes graphite as the negative electrode active material.

[0056] The above graphite may include at least one selected from the group consisting of natural graphite and artificial graphite.

[0057] In addition, other than the above graphite, the negative electrode active material that may be included 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.

[0058] 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).

[0059] 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.

[0060] Additionally, the negative electrode active material may further include a silicon-based negative electrode active material.

[0061] The negative active material may be included in an amount of 95 to 99.5 wt% based on the total weight of the negative active material layer. Specifically, the content of the negative active material may be 95 wt% or more or 96 wt% or more, and may be 99.5 wt% or less or 99 wt% or less. If the content of the negative active material is less than 95 wt%, the performance of the battery may deteriorate, and if it is more than 99.5 wt%, the mass transfer resistance may increase.

[0062]

[0063] In one embodiment of the present invention, the negative active material layer may further include a conductive material. 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 induce chemical changes in the battery, and has excellent electrical conductivity.

[0064] For example, conductive carbon can be used as the conductive material. The conductive carbon can be a carbon-based material having a crystal structure of graphene or graphite; a conductive fiber such as carbon fiber or metal fiber; fluorinated carbon; a metal powder such as aluminum powder or nickel powder; a conductive whiskey such as zinc oxide or potassium titanate; a conductive oxide such as titanium oxide; and a conductive polymer such as a polyphenylene derivative; which can be used alone or in combination of two or more, but is not necessarily limited thereto.

[0065] In addition, the conductive material may be typically included in an amount of 0.5 wt% to 3 wt% based on the total weight of the negative electrode active material layer, and specifically, the content of the conductive material may be 0.5 wt% or more, 1 wt% or more, or 1.5 wt% or more, and 3 wt% or less, 2.5 wt% or less, or 1 wt% or less. If the content of the conductive material is too low, less than 0.5 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 3 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 a conventional method known in the art, such as mixing or coating with the negative electrode active material, may be used.

[0066]

[0067] In one embodiment of the present invention, the negative active material layer may be solid electrolyte-free (SE-free).

[0068] In general, all-solid-state batteries, including solid electrolytes, have poor ionic conductivity compared to batteries containing liquid electrolytes. To compensate for this, solid electrolytes are introduced into the electrodes, and the solid electrolytes act as a lithium ion transfer path. However, there is a problem in that the solid electrolyte, which acts as a lithium ion transfer path, causes a side reaction with the carbon material contained in the electrode, resulting in resistance.

[0069] On the other hand, since the negative electrode for the all-solid-state battery of the present invention does not include a solid electrolyte, the problem of increased resistance due to the solid electrolyte can be prevented.

[0070]

[0071] In one embodiment of the present invention, the negative electrode for the all-solid-state battery further includes a negative electrode current collector, and one side of the negative electrode current collector may be in contact with one side of the negative electrode active material layer.

[0072] The above 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.

[0073]

[0074] Method for manufacturing a cathode for an all-solid-state battery

[0075] The present invention also relates to a method for manufacturing a negative electrode for an all-solid-state battery.

[0076] The method for manufacturing an anode for an all-solid-state battery according to the present invention comprises the steps of (S1) forming a slurry for forming an anode active material layer by mixing graphite as an anode active material and a binder in a solvent; (S2) forming a anode active material layer by coating the slurry for forming an anode active material layer on one surface of an anode current collector; and (S3) forming a porous carbon layer by coating a carbon slurry for forming a porous carbon layer on one surface of the anode active material layer.

[0077]

[0078] Hereinafter, the method for manufacturing a negative electrode for an all-solid-state battery according to the present invention will be described in more detail step by step.

[0079]

[0080] In one embodiment of the present invention, in step (S1), graphite as a negative electrode active material and a binder may be mixed in a solvent to form a slurry for forming a negative electrode active material layer. The types and contents of the negative electrode active material and the binder are as described above.

[0081] The solvent is not particularly limited as long as it is a solvent capable of forming a slurry for forming a negative electrode active material layer. For example, the solvent may be at least one selected from the group consisting of water, alcohol, acetone, dimethyl sulfoxide, formamide, and dimethylformamide. The alcohol may include at least one selected from the group consisting of methanol, ethanol, and isopropyl alcohol.

[0082] In addition, the concentration of the slurry for forming the negative electrode active material layer is not particularly limited as long as it is a concentration that can smoothly perform the coating process. For example, the concentration of the slurry for forming the negative electrode active material layer may be 5 to 30%. If the concentration of the slurry for forming the negative electrode active material layer is less than 5%, the concentration is dilute, and the slurry for forming the negative electrode active material layer may flow down without being coated on the substrate, and if it exceeds 30 wt%, the concentration is thick, and the coating may not be smooth. Specifically, the concentration of the slurry may be 5% or more, 10% or more, or 15% or more, and 30% or less or 25% or less. In addition, the concentration may be a concentration based on the weight of the solid content, and the solid content may mean a material included in the slurry other than the solvent.

[0083]

[0084] In one embodiment of the present invention, in the step (S2), the slurry for forming the negative electrode active material layer may be coated on one surface of the negative electrode current collector to form the negative electrode active material layer.

[0085] In addition, after coating the slurry for forming the negative electrode active material layer on the negative electrode current collector, a drying process may be performed to form the negative electrode active material layer.

[0086] In addition, the coating method is not particularly limited as long as it is a coating method that can be used in the art to form a coating layer. For example, the coating method may be selected from the group consisting of dip coating, spray coating, spin coating, die coating, gravure coating, micro-gravure coating, comma coating, and roll coating.

[0087] Additionally, the drying temperature may be 100°C to 150°C. If the drying temperature is less than 100°C, the drying may not be sufficiently performed to form a negative electrode active material layer, and if it is more than 150°C, the negative electrode active material layer may be deformed, such as cracked.

[0088]

[0089] In one embodiment of the present invention, in the step (S3), a carbon slurry for forming a porous carbon layer may be coated on one surface of the negative electrode active material layer to form a porous carbon layer.

[0090] The carbon slurry for forming the above porous carbon layer can be prepared by mixing carbon with a solvent. The concentration of the solvent and slurry used in preparing the carbon slurry may be the same as the concentration of the solvent and slurry used in preparing the slurry for forming the negative electrode active material layer in step (S2).

[0091] Additionally, the coating method may also be the same as described above in step (S2).

[0092] After coating the carbon slurry for forming the above porous carbon layer, the solvent evaporates during drying, forming pores inside, thereby forming a porous carbon layer. At this time, the more nano-sized and well-dispersed the carbon is, the more uniform the porous structure can be formed.

[0093]

[0094] All-solid-state batteries

[0095] The present invention also relates to an all-solid-state battery including a negative electrode for an all-solid-state battery.

[0096] An all-solid-state battery according to the present invention comprises a positive electrode; a negative electrode; and a solid electrolyte membrane interposed between the positive electrode and the negative electrode. The negative electrode refers to the negative electrode for the all-solid-state battery described above.

[0097]

[0098] In one embodiment of the present invention, the solid electrolyte membrane included in the all-solid-state battery may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte is not particularly limited as long as it is a solid electrolyte containing sulfur.

[0099] For example, the sulfide-based solid electrolyte may be represented by the following chemical formula 1:

[0100] <Chemical Formula 1>

[0101] Li a M b S c X d

[0102] In the above chemical formula 1, M is selected from P, Sn, Sb, As, and Ge;

[0103] wherein X is selected from Cl, Br and I,

[0104] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0105] Additionally, solid electrolytes may be amorphous or crystalline, or may be a mixture of amorphous and crystalline states.

[0106] The solid electrolyte membrane may further include a binder. Examples of the binder material include resins such as acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polyacrylic acid. The binder material may be the same as or different from the materials constituting the binder in the positive electrode active material layer and the negative electrode active material layer.

[0107]

[0108] In one embodiment of the present invention, the positive electrode included in the all-solid-state battery includes a positive electrode active material layer, and the positive electrode active material layer may be formed on one surface of the positive electrode current collector.

[0109] The above positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder. In addition, the positive electrode active material layer may additionally include a solid electrolyte.

[0110] 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-yNi-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.

[0111] In addition, the positive electrode active material may be included in an amount of 60 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 60 wt%, 65 wt% or more, or 70 wt% or more, and may be 90 wt% or less, 85 wt% or less, or 80 wt% or less. If the content of the positive electrode active material is less than 60 wt%, battery performance may deteriorate, and if it exceeds 90 wt%, mass transfer resistance may increase.

[0112] 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 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 whiskers 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).

[0113] The conductive material may typically be included in an amount of 1 wt% to 10 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the conductive material may be 1 wt% or more, 2 wt% or more, or 3 wt% or more, and 10 wt% or less, 9 wt% or less, or 8 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 10 wt%, too much, the amount of positive electrode active material may be relatively small, which may lower the capacity and energy density. The method of including the conductive material in the positive electrode is not particularly limited, and conventional methods known in the art, such as mixing or coating with the positive electrode active material, may be used.

[0114] In addition, the binder is a component that assists in the bonding of the positive electrode active material and the conductive material and the bonding to the 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 acetate It may include at least one selected from the group consisting of 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).

[0115] In addition, the binder may be included in an amount of 1 wt% to 10 wt% based on the total weight of the positive electrode active material layer, and specifically, the content of the binder may be 1 wt% or more, 2 wt% or more, or 3 wt% or more, and 10 wt% or less, 9 wt% or less, or 8 wt% or less. If the content of the binder is less than 1 wt%, the adhesive strength between the positive electrode active material and the positive electrode current collector may be reduced, and if it exceeds 10 wt%, the adhesive strength may be improved, but the content of the positive electrode active material may be reduced, which may lower the battery capacity.

[0116] Additionally, the solid electrolyte may be a sulfide-based solid electrolyte. The sulfide-based solid electrolyte is not particularly limited as long as it is a solid electrolyte containing sulfur.

[0117] The solid electrolyte may be included in an amount of 5 to 20 wt% based on the total weight of the positive electrode active material layer. When the solid electrolyte is included in the above range, ionic conductivity may be improved. Specifically, the content of the solid electrolyte may be 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, or 10 wt% or more, and may be 20 wt% or less, 19 wt% or less, 18 wt% or less, 17 wt% or less, 16 wt% or less, 15 wt% or less, 14 wt% or less, 13 wt% or less, or 12 wt% or less.

[0118]

[0119] In addition, 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.

[0120] 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, the positive electrode current collector may be copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, silver, etc., or an aluminum-cadmium alloy.

[0121] 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.

[0122] The positive electrode as described above can be manufactured according to a conventional method, and specifically, a composition for forming a positive electrode active material layer prepared by mixing a positive electrode active material, a conductive agent, and a binder in an organic solvent phase is applied and dried on a positive electrode current collector, and optionally, to improve electrode density, it can be manufactured by compression molding the positive electrode current collector. At this time, it is preferable to use an organic solvent that can uniformly disperse the positive electrode active material, binder, and conductive agent and is easily evaporated. Specifically, examples thereof include acetonitrile, methanol, ethanol, tetrahydrofuran, water, isopropyl alcohol, and the like.

[0123]

[0124] battery module

[0125] 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.

[0126] At this time, 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), a plug-in hybrid electric vehicle (PHEV), etc.; 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.

[0127] 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.

[0128]

[0129] Example 1

[0130] (1) Manufacturing of cathode for all-solid-state battery

[0131] Natural graphite as a negative active material and polyvinylidene fluoride (PVdF) as a binder were mixed in a weight ratio of 97.5:2.5, and then the slurry for forming a negative active material layer mixed in an ethanol solvent was coated on stainless steel (SS), which is a negative current collector, and then dried at 100°C to form a negative active material layer. At this time, the concentration of the slurry for forming the negative active material layer was set to 20% based on the solid content weight. The solid content refers to natural graphite and the binder.

[0132] Thereafter, carbon black (Asahi Carbon, CB78) was mixed with an ethanol solvent to prepare a slurry for forming a porous carbon layer. At this time, the concentration of the slurry for forming a porous carbon layer was set to 20%. The slurry for forming a porous carbon layer was coated on the negative electrode active material layer and dried at 120°C to form a porous carbon layer with a thickness of 9 μm.

[0133]

[0134] (2) Manufacturing of positive electrode for all-solid-state battery

[0135] LiNi as a cathode active material 0.8 Co 0.1 Mn 0.1 After mixing 80 wt% of O2 (NCM811), 11 wt% of Li6PS5Cl as a solid electrolyte, 5 wt% of a conductive material (Vapor Grown Carbon Fiber, VGCF), and 4 wt% of a binder polymer (polyvinylidene fluoride, PVDF), the solvent N-methylpyrrolidone was further added to consider the viscosity, thereby preparing a slurry of a positive electrode active material.

[0136] The above-mentioned manufactured positive electrode active material slurry was applied to an aluminum current collector having a thickness of 20 μm, and then vacuum dried at 120°C for 24 hours to manufacture a positive electrode.

[0137]

[0138] (3) Manufacturing of solid electrolyte membrane

[0139] A slurry for forming a sulfide-based solid electrolyte membrane was prepared by mixing Li6PS5Cl having an argyrodite structure as a sulfide-based solid electrolyte and acrylonitrile butadiene rubber (NBR) as a binder in a weight ratio of 90:10 with butyrate, a nonpolar solvent, so that the solid content was 50 wt%.

[0140] The slurry for forming the above sulfide-based solid electrolyte membrane was applied onto a PET (polyethyleneterephthalate) substrate, overcoated with a bar coater, and then vacuum-dried at 70°C for 5 hours to form a sulfide-based solid electrolyte membrane.

[0141]

[0142] (4) Manufacturing of all-solid-state batteries

[0143] An all-solid-state battery was manufactured by interposing the solid electrolyte membrane between the negative electrode and positive electrode manufactured above.

[0144]

[0145] Example 2

[0146] The same method as Example 1 was used, except that the thickness of the porous carbon layer was set to 15 μm.

[0147]

[0148] Comparative Example 1

[0149] When manufacturing an anode for an all-solid-state battery, the same method as Example 1 was used except that a porous carbon layer was not formed.

[0150]

[0151] Experimental Example 1: Battery Performance Measurement

[0152] The capacity capability of the all-solid-state batteries manufactured in the examples and comparative examples was observed through a protocol in which the batteries were activated in a charger / discharger at 0.05 C for 2 cycles and then discharged up to 1 C. Specifically, the capacity capability was observed through a protocol in which 0.05 C CC / CV (Constant Current / Constant Voltage) charging was performed in the charger / discharger, 0.05 C CC (Constant Current) discharge was performed for 2 cycles, and then 0.1 C CC / CV charging was maintained, while CC discharge was performed at 0.1 C / 0.2 C / 0.33 C / 0.5 C / 1 C.

[0153]

[0154] Figure 1 is a graph showing the capacity retention (cycle retention) according to the number of cycles of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Example 1.

[0155] Referring to Figure 1, it can be seen that Comparative Example 1, in which the negative active material layer is not coated with a carbon layer, has a rapidly decreasing capacity retention as the number of cycles passes 12 to 13.

[0156] In addition, it can be seen that Example 2 has slightly inferior capacity preservation compared to Example 1. It can be seen that this is due to the fact that the thickness of the porous carbon layer in Example 2 is thicker than that in Example 1.

[0157]

[0158] Figure 2 is a graph showing the Coulomb efficiency according to the number of cycles of the all-solid-state batteries manufactured in Examples 1 and 2 and Comparative Example 1.

[0159] Referring to Fig. 2, Comparative Example 1, in which the negative active material layer was not coated with a porous carbon layer, showed a rapid decrease in coulombic efficiency as the charge capacity increased within 15 cycles, resulting in a short circuit. This can be inferred to be due to an insufficiently secured ion transfer path within the negative electrode.

[0160] Additionally, it can be seen that the capacity conservation and Coulomb efficiency of the battery influence each other.

[0161]

[0162] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the patent claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

Claims

1. Negative current collector; A negative electrode active material layer formed on one surface of the negative electrode current collector and including graphite; and An all-solid-state battery negative electrode comprising a porous carbon layer formed on one surface of the negative electrode active material layer.

2. In paragraph 1, An anode for an all-solid-state battery, wherein the porosity of the porous carbon layer is 30% to 60%.

3. In paragraph 1, An anode for an all-solid-state battery, wherein the thickness of the porous carbon layer is greater than 0 ㎛ and less than or equal to 10 ㎛.

4. In paragraph 1, An anode for an all-solid-state battery, wherein the porous carbon layer comprises at least one type of carbon black selected from the group consisting of thermal black, acetylene black, and ketjen black.

5. In paragraph 1, An anode for an all-solid-state battery, wherein the anode active material layer further includes a binder.

6. In paragraph 5, An anode for an all-solid-state battery, wherein the binder comprises at least one selected from the group consisting of polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), and carboxymethyl cellulose (CMC).

7. In paragraph 5, An anode for an all-solid-state battery, wherein the binder is included in an amount of 1 to 5 wt% based on the total weight of the anode active material layer.

8. In paragraph 1, An all-solid-state battery negative electrode, wherein the negative active material layer is solid electrolyte-free (SE-free).

9. In paragraph 1, An anode for an all-solid-state battery, wherein the anode current collector comprises stainless steel (SS), copper (Cu), nickel (Ni), or titanium (Ti).

10. An all-solid-state battery comprising: a positive electrode; a negative electrode of the first clause; and a solid electrolyte membrane interposed between the positive electrode and the negative electrode.

11. In paragraph 10, An all-solid-state battery, wherein the solid electrolyte membrane includes a sulfide-based solid electrolyte.

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