Negative electrode for all-solid-state battery and all-solid-state battery comprising the same

Abstract

The present invention relates to a negative electrode for a full solid battery and a full solid battery including the same, the negative electrode including a negative electrode coating layer including a carbon-based material, a metal, and a binder containing polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:4 to 5:2.

Description

Technical Field

[0001] The implementation method involves all-solid-state batteries. Background Technology

[0002] Recently, battery-powered electronic devices, such as mobile phones, laptops, and electric vehicles, have been developing rapidly.

[0003] As such, the development of all-solid-state batteries using lithium metal as the negative electrode is underway. All-solid-state batteries refer to batteries in which all materials are solid, and particularly those using solid electrolytes. Because the electrolyte in an all-solid-state battery is solid, it is structurally rigid and has a low risk of fire or explosion due to leakage caused by external impacts, etc. Furthermore, the battery shape can be formed in various ways. Summary of the Invention

[0004] Technical issues

[0005] One implementation provides a negative electrode for an all-solid-state battery that exhibits low resistance, thereby demonstrating superior coulombic efficiency and excellent cycle life characteristics.

[0006] Another embodiment provides an all-solid-state battery including the negative electrode.

[0007] Technical solution

[0008] One embodiment provides a negative electrode for an all-solid-state battery, the negative electrode comprising a negative electrode coating comprising a binder containing polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:4 to 5:2; a carbon-based material; and a metal.

[0009] Another embodiment provides an all-solid-state battery, which includes the negative electrode, the positive electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0010] Beneficial effects

[0011] According to one embodiment, the negative electrode for an all-solid-state battery includes an aqueous binder, thus exhibiting low resistance, excellent initial efficiency, and excellent cycle life characteristics. Attached Figure Description

[0012] Figure 1 A schematic diagram illustrating a negative electrode for an all-solid-state battery according to one embodiment.

[0013] Figure 2 A schematic cross-sectional view illustrating an all-solid-state battery according to one embodiment. Detailed Implementation

[0014] Embodiments of the invention will now be described in detail. However, these embodiments are provided, and this disclosure is not limited thereto, and may be defined by the scope of the claims described later.

[0015] The terminology used in this specification is for explaining the embodiments, but is not intended to limit the embodiments. Singular expressions include plural expressions unless the context clearly specifies otherwise.

[0016] The term "combination thereof" may include mixtures of components, laminates, composites, copolymers, alloys, blends, and reactants.

[0017] The terms “comprise,” “include,” or “have” are used to indicate the presence of features, quantities, steps, components, or combinations thereof that are performed, but it should be understood that the possibility of the presence or addition of one or more other features, quantities, steps, components, or combinations thereof is not excluded in advance.

[0018] Throughout the instruction manual, unless explicitly stated otherwise, the words “comprise” and variations such as “comprises” or “comprising” shall be understood to imply inclusion of the elements described, but not to exclude any other elements.

[0019] Furthermore, the terms “about” and “substantially” used throughout this specification mean that, in the presence of inherent permissible errors in preparation and materials, the numerical values ​​have the meaning corresponding to such errors, and are used in the sense of being close to or near the value. They are intended to aid in understanding the invention and to prevent irresponsible infringers from unfairly exploiting the precise or absolute values ​​mentioned in this disclosure.

[0020] In the specification, A and / or B, as well as A or B, are not exclusive terms and indicate A, B, or both A and B.

[0021] Unless otherwise specified in the specification, it will be understood that when an element (such as a layer, film, region, plate, etc.) is referred to as being "on" or "above" another element, it may be directly on, directly connected to, or directly coupled to the other element or layer, or one or more intermediary elements may be present.

[0022] As used herein, “particle size” or “particle diameter” may refer to the average particle diameter. Alternatively, the average particle diameter may be defined as the average particle diameter (D50), which indicates the diameter of the particle at the 50% cumulative volume point of the cumulative size distribution curve. Particle diameter can be measured using methods well known to those skilled in the art (e.g., by a particle size analyzer or by transmission electron microscopy, scanning electron microscopy, or field emission scanning electron microscopy (FE-SEM)). In other embodiments, particle diameter can be determined by measuring and analyzing data using a dynamic light scattering measurement device, counting the number of particles for each particle size range, and calculating the average particle diameter (D50) value therefrom, or by measuring the particle diameter using a laser diffraction method. Laser diffraction can be achieved by dispersing the particles to be measured in a dispersion solvent and introducing them into a commercially available laser diffraction particle measurement device (e.g., the MT 3000 available from Microtrac, Inc.), irradiating them with ultrasound at a power of 60 W at approximately 28 kHz, and calculating the average particle diameter (D50) of the 50% standard of the particle size distribution in the measurement device.

[0023] The term "thickness" can be measured by taking a photograph with an optical microscope, such as a scanning electron microscope.

[0024] According to one embodiment, the negative electrode for an all-solid-state battery includes a negative electrode coating comprising a binder containing polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:4 to 5:2; a carbon-based material; and a metal.

[0025] Because water-based binders (such as polyacrylic acid and styrene-butadiene rubber) are used as binders for negative electrode coatings, they are environmentally friendly.

[0026] In addition, the use of polyacrylic acid can reduce resistance, and the use of styrene-butadiene rubber can improve adhesive strength.

[0027] If polyacrylic acid and styrene-butadiene rubber are included in a weight ratio of 5:4 to 5:2, the effects of using polyacrylic acid and styrene-butadiene rubber together can be achieved.

[0028] The use of polyacrylic acid can reduce electrical resistance, but it can also reduce adhesive strength; however, this reduction in adhesive strength can be prevented by using styrene-butadiene rubber together, especially when polyacrylic acid and styrene-butadiene rubber are used in a weight ratio of 5:4 to 5:2. Thus, using polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:4 to 5:2 effectively reduces electrical resistance while maintaining adhesive strength at a level comparable to that achieved when using styrene-butadiene rubber alone. Therefore, capacity and cycle life characteristics can be improved.

[0029] If the weight ratio of polyacrylic acid and styrene-butadiene rubber falls outside this range, it is undesirable. For example, if the weight ratio of polyacrylic acid / styrene-butadiene rubber is less than 5 / 4, the resistance may decrease, while if it exceeds 5 / 2, the adhesive strength may decrease.

[0030] In one embodiment, based on a total of 100 wt% of negative electrode coating, the amount of binder can be 6 wt% to 10 wt% or 6.5 wt% to 8.5 wt%. If the amount of binder falls within this range, advantages such as excellent phase stability of the composition and excellent dispersibility of carbonaceous materials and metals can be obtained in the preparation of the negative electrode coating composition.

[0031] In the negative electrode coating, carbonaceous materials and metals can exist in the form of a mixture, or metals can be loaded onto carbonaceous materials.

[0032] Carbon-based materials may be, for example, crystalline carbon, amorphous carbon, or combinations thereof, or may be amorphous carbon. Crystalline carbon may be, for example, natural graphite, synthetic graphite, mesophase carbon microspheres, carbon nanotubes, graphene, or combinations thereof. Crystalline carbon may have no specific shape, and may be sheet-like, flake-like, spherical, or fibrous. Amorphous carbon may be, for example, carbon black, acetylene black, superconducting acetylene black, Ketjen black, furnace black, activated carbon, graphene, or combinations thereof. Carbon black may be Super P (available from Timcal, Ltd.). Amorphous carbon is not limited to these, and any material that can be classified as amorphous carbon in the art may be used.

[0033] In one embodiment, the carbon-based material may be a single particle or an aggregate product having secondary particles in which primary particles aggregate. If the carbon-based material is a single particle, the size of the carbon-based material may have an average particle size of 100 nm or smaller (e.g., nanometer size of 10 nm to 100 nm).

[0034] If the carbon-based material is an aggregate product, the particle size of the primary particles can be 20 nm to 100 nm, and the particle size of the secondary particles can be 1 μm to 20 μm.

[0035] In one embodiment, the particle size of the primary particles may be 20 nm~, 100 nm, 20 nm~90 nm, 20 nm~80 nm or 30 nm~70 nm.

[0036] In one embodiment, the particle size of the secondary particles can be 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 μm.

[0037] The primary particles may be spherical, ellipsoidal, plate-like, or a combination thereof, and in some embodiments, the primary particles may be spherical, ellipsoidal, or a combination thereof.

[0038] The metal may be Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or combinations thereof, or may be Ag. Including the metal in the negative electrode coating can further improve the conductivity of the negative electrode.

[0039] The metal can be in the form of nanoparticles, and the size of the metal nanoparticles (e.g., the average size of the metal nanoparticles) can be 5 nm to 800 nm, 5 nm to 700 nm, 5 nm to 500 nm, or 5 nm to 300 nm; however, if it is nanoscale, it can be used appropriately. Using metal nanoparticles with nanoscale dimensions can improve battery characteristics, such as the cycle life characteristics of all-solid-state batteries. If the metal particle size increases to the micrometer scale, the uniformity of the metal particles in the negative electrode coating can decrease, which can lead to an increase in current density and a deterioration in cycle life characteristics in specific regions, and is therefore undesirable.

[0040] In one embodiment, based on a total of 100 wt% of negative electrode coating, the amount of metal may be 14 wt% to 35 wt%, 18 wt% to 25 wt%, or 20 wt% to 24 wt%.

[0041] In addition, based on a total negative electrode coating of 100wt%, the amount of carbon material can be 55wt%~80wt%, 60wt%~75wt%, or 65wt%~70wt%.

[0042] In one embodiment, the negative electrode coating may further include a solid electrolyte. The solid electrolyte may be an inorganic solid electrolyte (such as a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, etc.) or a solid polymer electrolyte.

[0043] In one embodiment, the sulfide solid electrolyte may be Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, such as I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, or Li2S-P2S5-Z. m S n (where m and n are each an integer greater than 0 and less than 12, and Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MOq (where p and q are each an integer greater than 0 and less than 12, and M is one of P, Si, Ge, B, Al, Ga, In), Li a M b P c S d A e (Where a, b, c, d, and e are each an integer of 0 or greater and 12 or less, and M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I). Sulfide-based solid electrolytes can be, for example, Li. 7-x PS 6-x F x (0≤x≤2), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2) or Li 7-x PS 6-x I x (0≤x≤2). Furthermore, specifically, it can be Li3PS4 or Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5I, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 wait.

[0044] In one embodiment, the sulfide solid electrolyte may be a sulfide solid electrolyte of the argentite-germanium type. The sulfide solid electrolyte of the argentite-germanium type may be, for example, Li... a M b P c S d A e (where a, b, c, d, and e are each an integer of 0 or greater and 12 or less, and M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I).

[0045] Specific examples could be Li3PS4 and Li7P3S. 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 Li 6.2 PS 5.2 Br 0.8 Li6PS5I, Li5.75 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 PS 4.75 Cl 1.25 、(Li 5.72 Cu 0.03 PS 4.75 Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.70 (SO4) 0.05 )Cl 1.25 、(Li 5.69 Cu 0.06 )P(S 4.60 (SO4) 0.15 )Cl 1.25 、(Li 5.72 Cu 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 、(Li 5.72 Na 0.03 )P(S 4.725 (SO4) 0.025 )Cl 1.25 Li 5.75 P(S 4.725 (SO4) 0.025 )Cl 1.25 Or combinations thereof, but not limited to these.

[0046] Sulfide solid electrolytes can be amorphous, crystalline, or a combination thereof. Sulfide solid electrolytes can be prepared, for example, by mixing Li₂S and P₂S₅ in a molar ratio of 50:50–90:10 or 50:50–80:20. Within this mixing ratio range, sulfide solid electrolytes exhibiting excellent ionic conductivity can be prepared. Ionic conductivity can be further improved by including other components (such as SiS₂, GeS₂, B₂S₃, etc.).

[0047] As a mixing method for preparing a sulfide-based solid electrolyte from a sulfur-containing raw material, a mechanical grinding method or a solution method can be applied. Mechanical grinding is a method in which starting materials and ball milling media are placed in a reactor and vigorously stirred to crush the starting materials into fine particles and mix them. The solution method can provide a solid electrolyte in the form of a precipitate by mixing the starting materials in a solvent. If heat treatment is performed after mixing, the crystals of the solid electrolyte can become stronger and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be prepared by mixing sulfur-containing raw materials and performing heat treatment two or more times, and in this case, a sulfide-based solid electrolyte with high ionic conductivity and strength can be prepared.

[0048] The sulfide-based solid electrolyte can also be a commercially available solid electrolyte.

[0049] The oxide-based solid electrolyte can be, for example, Li 1+x Ti 2-x Al(PO4)3 (LTAP) (0 ≤ x ≤ 4), Li 1+x+y Al x Ti 2- x Si y P 3-y O 12 (0 < x < 2, 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (0 ≤ x < 1, 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), Li 1+x+y (Al, Ga) x [[ID=4​​​​​​​​​​​​3+x La3M2O 12 (where M = Te, Nb or Zr, and x is an integer from 1 to 10) or a mixture thereof.

[0050] The solid polymer electrolyte may include at least one selected from, for example, the following: polyethylene oxide, poly(diallyldimethylammonium) trifluoromethanesulfonylimide (poly(diallyldimethylammonium) TFSI), Cu3N, Li3N, LiPON, Li3PO4.Li2S.SiS2, Li2S·GeS2·Ga2S3, Li2O·11Al2O3, Na2O·11Al2O3, (Na,Li) 1+x Ti 2-x Al x (PO4)3 (0.1 ≤ x ≤ 0.9), Li 1+x Hf 2-x Al x (PO4)3 (0.1 ≤ x ≤ 0.9), Na3Zr2Si2PO 12 、Li3Zr2Si2PO 12 、Na5ZrP3O 12 、Na5TiP3O 12 、Na3Fe2P3O 12 、Na4NbP3O 12 、sodium silicate, Li 0.3 La 0.5 TiO3, Na5MSi4O 12 (where M is a rare earth element such as Nd, Gd, Dy, etc.) Li5ZrP3O 12 、Li5TiP3O 12 、Li3Fe2P3O 12 、Li4NbP3O 12 、Li 1+x (M,Al,Ga) x (Ge 1-y Ti y ) 2-x (PO4)3 (0 ≤ x ≤ 0.8, 0 ≤ y ≤ 1.0, and M is Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), Li 1+x+y Q x Ti 2-x Si y P 3-y O 12 (0 < x ≤ 0.4, 0 < y ≤ 0.6, and Q is Al or Ga), Li6BaLa2Ta2O 12 、Li7La3Zr2O 12 、Li5La3Nb2O 12, Li5La3M2O 12 (where M is Nb, Ta) or Li 7+x A x La 3-x Zr2O 12 (0 < x < 3, and A is Zn).

[0051] The halide solid electrolyte may include an Li element, an M element (where M is a metal other than Li), and an X element (where X is a halogen). X may be, for example, F, Cl, Br, and I. In particular, the halide solid electrolyte may include at least one of Br and Cl as X. M may be, for example, a metallic element such as Sc, Y, B, Al, Ga, In, etc.

[0052] The composition of the halide solid electrolyte is not limited, but the halide solid electrolyte may be represented by Li 6- 3a M a Br b Cl c (where M is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, b + c = 6). In this article, a may be 0.75 or greater or 1 or greater, and a may be 1.5 or less. b may be 1 or greater or 2 or greater. In addition, c may be 3 or greater or 4 or greater. Examples of the halide solid electrolyte may be Li3YBr6, Li3YCl6, or Li3YBr2Cl4.

[0053] The negative electrode coating may further include additives such as, for example, fillers, dispersants, ion conductive materials, etc. In addition, the fillers, dispersants, ion conductive materials, etc. that may be included in the negative electrode coating may be materials known in the relevant technical fields commonly used in all-solid-state batteries.

[0054] The negative electrode coating may have a thickness of, for example, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm, but is not limited thereto.

[0055] According to one embodiment, the negative electrode may further include a current collector that supports the negative electrode coating.

[0056] The current collector may be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof, and may have a foil shape or a sheet shape. The thickness of the negative electrode current collector may be 1 μm to 20 μm, 5 μm to 15 μm, or 7 μm to 10 μm.

[0057] The current collector may include a metal as a substrate and may further include a thin film on the substrate. The thin film may include, but is not limited to, elements capable of forming alloys with lithium, such as gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, or combinations thereof, and any element known in the art that can form alloys with lithium may be used. When the current collector further includes a thin film, a flatter lithium-containing layer can be formed when lithium is deposited during charging to form a lithium-containing layer, thereby further improving the cycle life characteristics of the all-solid-state battery.

[0058] The thickness of the thin film can be 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is within this range, the cycle life characteristics can be further enhanced.

[0059] In one embodiment, the negative electrode coating refers to a layer that facilitates the movement of lithium ions released from the positive electrode active material to the negative electrode during the charging and discharging of an all-solid-state battery, thereby promoting their deposition on the surface of the current collector. For example, a lithium-containing layer (e.g., a lithium deposition layer) can be formed between the current collector and the negative electrode coating due to lithium ion deposition, and this lithium deposition layer acts as the negative electrode active material, and this negative electrode is generally referred to as a deposited negative electrode.

[0060] Metals and carbon-based materials included in the negative electrode coating do not act as negative electrode active materials that directly participate in the charging and discharging reactions. Deposited negative electrodes refer to negative electrodes that do not include negative electrode active materials during battery manufacturing; instead, a lithium-containing layer acts as the negative electrode active material.

[0061] According to one embodiment, the negative electrode may further include a lithium-containing layer formed between the current collector and the negative electrode coating during initial charging after battery fabrication. The thickness of the lithium-containing layer may be 1 μm to 1000 μm, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium-containing layer falls within this range, it can effectively function as a lithium reservoir and further enhance cycle life characteristics.

[0062] The lithium-containing layer can be formed during charging after the battery is manufactured. As lithium ions are released from the positive electrode active material, pass through the solid electrolyte, and migrate toward the negative electrode, lithium is deposited and deposited on the negative electrode current collector.

[0063] Charging can be a formation process, which can be carried out one to three times at approximately 25°C to 50°C at 0.05C to 1C. If lithium is deposited and forms a lithium-containing layer, the lithium included in the lithium-containing layer ionizes during discharge and moves toward the positive electrode; therefore, the lithium can be used as the active material of the negative electrode.

[0064] In one embodiment, since the lithium-containing layer is located between the current collector and the negative electrode coating, the negative electrode coating can serve as a protective layer for the lithium-containing layer, thus suppressing the deposition and growth of lithium dendrites. This ensures suppression of capacity decay and short circuits in the all-solid-state battery, thereby improving the cycle life of the all-solid-state battery.

[0065] All-solid-state batteries

[0066] An all-solid-state battery according to one embodiment includes a negative electrode, a positive electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0067] <Solid Electrolyte Layer>

[0068] In one embodiment, the solid electrolyte layer may include a solid electrolyte. This may be an inorganic solid electrolyte (such as a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, etc.) or a solid polymer electrolyte.

[0069] In one embodiment, the solid electrolyte may be a sulfide-based solid electrolyte. Sulfide-based solid electrolytes are suitable because they exhibit superior ionic conductivity and excellent cycle life characteristics over a wider operating range compared to other solid electrolytes, such as oxide-based solid electrolytes.

[0070] The sulfide-based solid electrolyte, oxide-based solid electrolyte, halide-based solid electrolyte, and solid polymer electrolyte are the same as those described above. Furthermore, the solid electrolyte included in the solid electrolyte layer may be the same as or different from the solid electrolyte included in the negative electrode coating.

[0071] Solid electrolytes may have a particulate shape. In this paper, the average particle size (D50) of the solid electrolyte may be 5.0 μm or smaller, for example, 0.1 μm to 5.0 μm, 0.5 μm to 5.0 μm, 0.5 μm to 4.0 μm, 0.5 μm to 3.0 μm, 0.5 μm to 2.0 μm or 0.5 μm to 1.0 μm.

[0072] The solid electrolyte layer may further include a binder. In this document, the binder may be, but is not limited to, styrene-butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate polymers, or combinations thereof, and may be any material commonly used in the relevant field. Acrylate polymers may be butyl acrylate, polyacrylate, polymethacrylate, or combinations thereof.

[0073] The amount of binder in the solid electrolyte layer can be adjusted appropriately and there is no need to limit it.

[0074] A solid electrolyte layer can be prepared by adding a solid electrolyte to an adhesive solution, coating it onto a substrate film, and drying it. The adhesive solution may include isobutyl isobutyrate, xylene, toluene, benzene, hexane, or combinations thereof as solvents. The preparation of solid electrolyte layers is widely known in the art, so its detailed description will be omitted in this specification.

[0075] The thickness of the solid electrolyte layer can be, for example, 10 µm to 150 µm.

[0076] The solid electrolyte layer may further include alkali metal salts and / or ionic liquids and / or conductive polymers.

[0077] Alkali metal salts can be, for example, lithium salts. In the solid electrolyte layer, the amount of lithium salt can be 1 M or higher, for example, 1 M to 4 M. In this case, the lithium salt can improve the lithium-ion mobility of the solid electrolyte layer, thereby improving the ionic conductivity.

[0078] The lithium salt may be, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalate)borate (LiBOB), lithium difluorooxalateborate (LIODFB), lithium difluoro(oxalate)borate (LiDFOB), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or mixtures thereof.

[0079] Furthermore, lithium salts can be imides, such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) or lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). Lithium salts can appropriately retain their chemical reactivity with ionic liquids, thus maintaining or improving ionic conductivity.

[0080] Ionic liquids are salts composed solely of ions, have a melting point at or below room temperature, and are liquid at room temperature, or room temperature molten salts.

[0081] Ionic liquids may be compounds including: a) at least one cation selected from ammonium compounds, pyrrolidine-onium compounds, pyridinium compounds, pyrimidine-onium compounds, imidazolium compounds, piperidinium compounds, pyrazolium compounds, oxazolium compounds, pyridazinium compounds, phosphonium compounds, sulfur compounds, triazolium compounds, or mixtures thereof; and b) compounds selected from BF4.- PF6 - AsF6 - SbF6 - AlCl4 - HSO4 - ClO4 - CH3SO3 - CF3CO2 - Cl - ,Br - I - BF4 - SO4 - CF3SO3 - (FSO2)2N - (C2F5SO2)2N - (C2F5SO2)(CF3SO2)N - Or (CF3SO2)2N - At least one anion in it.

[0082] The ionic liquid may be, for example, selected from at least one of the following: N-methyl-N-propylpyrrolidone bis(trifluoromethanesulfonyl)imine, N-butyl-N-methylpyrrolidone bis(3-trifluoromethanesulfonyl)imine, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide or 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide.

[0083] In the solid electrolyte layer, the weight ratio between the solid electrolyte and the ionic liquid can be in the range of 0.1:99.9 to 90:10, for example, in the ranges of 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer within this range can increase the electrochemical contact area with the electrode, thus maintaining or improving ionic conductivity. Correspondingly, the energy density, discharge capacity, rate performance, etc., of the all-solid-state rechargeable battery can be improved.

[0084] <Positive electrode>

[0085] According to one embodiment, the positive electrode for an all-solid-state battery includes a positive electrode current collector and a layer of positive electrode active material on the surface of the positive electrode current collector.

[0086] The positive electrode active material layer may include a positive electrode active material. The positive electrode active material may be a positive electrode active material capable of reversibly inserting and deintercalating lithium ions. For example, the positive electrode active material may include one or more composite oxides of lithium and metals selected from cobalt, manganese, nickel, and combinations thereof. An example of a positive electrode active material may be Li. a A 1-b B1 b D 1 2(0.90≤a≤1.8、0≤b≤0.5);Li a HAVE BEEN 1-b B 1 b O 2-c D 1 c (0.90≤a≤1.8、0≤b≤0.5、0≤c≤0.5);Li a HAVE BEEN 2-b B 1 b O 4-c D 1 c (0.90≤a≤1.8、0≤b≤0.5、0≤c≤05);Li a Ni 1-b-c Co b B 1 c D 1 α (0.90≤a≤1.8、0≤b≤0.5、0≤c≤0.5、0<α≤2);Li a Ni 1-b-c Co b B 1 c O 2-α F 1 α (0.90≤a≤1.8、0≤b≤0.5、0≤c≤0.5、0<α<2);Li a Ni 1-b-c Co b B 1 c O 2-α F 1 2(0.90≤a≤1.8、0≤b≤0.5、0≤c≤0.5、0<α<2);Li a Ni 1-b-c Mr b B 1 c D 1 α (0.90≤a≤1.8、0≤b≤0.5、0≤c≤0.5、0<α≤2);Li a Ni 1-b-c Mr b B 1 c O 2-α F 1 α(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b B 1 c O 2-α F 1 2 (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b E c G d O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a MnG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI 1 O2; LiNiVO4; Li (3-f) J2(PO4)3 (0≤f≤2); Li (3-f) Fe2(PO4)3 (0≤f≤2); or LiFePO4.

[0087] In the chemical formula, A is selected from Ni, Co, Mn, or combinations thereof; B 1 Selected from Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof; D 1 Selected from O, F, S, P or combinations thereof; E selected from Co, Mn or combinations thereof; F 1 Selected from F, S, P, or combinations thereof; G selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q selected from Ti, Mo, Mn, or combinations thereof; I 1selected from Cr, V, Fe, Sc, Y, or a combination thereof; J is selected from V, Cr, Mn, Co, Ni, Cu, or a combination thereof; L 1 is selected from Mn, Al, or a combination thereof.

[0088] According to one embodiment, the positive electrode active material may be a ternary lithium transition metal oxide, such as LiNi x Co y Al z O2 (NCA), LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1), etc.

[0089] The compound may have a coating on its surface or may be mixed with another compound having a coating. The coating may include at least one coating element compound selected from the group consisting of: oxides of coating elements, hydroxides of coating elements, hydroxyoxides of coating elements, oxycarbonates of coating elements, and hydroxycarbonates of coating elements. The compound used for the coating may be amorphous or crystalline. The coating elements included in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating may be formed by any coating method (e.g., spraying, dip coating, etc.), as long as the elements are applied to the compound in a manner that does not adversely affect the properties of the positive electrode active material, and since those skilled in the art will readily understand these methods, their detailed descriptions are not elaborated.

[0090] In addition, the coating may be any known coating material for the positive electrode active material of a all-solid-state battery. For example, it may be a buffer layer for reducing the interfacial resistance between the positive electrode active material and the solid electrolyte. For example, the buffer layer may include a lithium-metal-oxide, and the metal may be one or more elements selected from Al, B, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ta, V, W, or Zr. Specific examples of the buffer layer may be Li2O-ZrO2 (LZO), LiNbO2, etc.

[0091] Furthermore, if the positive electrode active material is a ternary material including nickel, cobalt, and manganese or nickel, cobalt, and aluminum, the capacity density of the all-solid-state battery can be further improved, and the metal dissolution of the positive electrode active material in the charged state can be further reduced. Therefore, the long-term reliability and cycle characteristics of the all-solid-state battery in the charged state can be further improved.

[0092] The average particle size of the positive electrode active material can be 1 μm to 25 μm, for example, 3 μm to 25 μm, 1 μm to 20 μm, 1 μm to 18 μm, 3 μm to 15 μm, or 5 μm to 15 μm. For example, the positive electrode active material can include small particles with an average particle size (D50) of 1 μm to 9 μm and large particles with an average particle size (D50) of 10 μm to 25 μm. Positive electrode active materials with such a particle size range can be coordinatingly mixed with other components in the positive electrode active material layer, and high capacity and high energy density can be achieved.

[0093] The positive electrode active material can be a secondary particle composed of multiple primary particles aggregated together, or a monocrystalline state (single crystal). Furthermore, the positive electrode active material can be spherical, nearly spherical, or polyhedral, or it can have no specific shape.

[0094] In the positive electrode active material layer, the amount of positive electrode active material is not limited and can be within any range applicable to the positive electrode layer of conventional rechargeable all-solid-state batteries. For example, based on a total of 100 wt% of positive electrode active material layer, the positive electrode active material can be included in 55 wt% to 99.5 wt% (e.g., 65 wt% to 95 wt% or 75 wt% to 91 wt%).

[0095] The positive electrode active material layer may further include a binder and / or a conductive material.

[0096] The adhesive may be polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but is not limited to these.

[0097] Based on a total of 100 wt% positive electrode active material layer, a binder may be included in an amount of 0.1 wt% to 5 wt% or 0.1 wt% to 3 wt%. Within this range, the binder can exhibit sufficient adhesion without degrading battery performance.

[0098] This includes conductive materials to impart conductivity to the electrodes, and any material that has electronic conductivity can be used without causing chemical changes in the battery. Examples of conductive materials may include: carbon-based materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, carbon nanotubes, etc.; metallic materials, including metal powders or metal fibers of copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0099] Based on a total of 100 wt% positive electrode active material layer, conductive material can be included in amounts of 0.1 wt% to 5 wt% or 0.1 wt% to 3 wt%. Conductive material in the above range can improve conductivity without degrading battery performance.

[0100] The positive electrode active material layer may further include a solid electrolyte. The solid electrolyte included in the positive electrode active material layer may be an inorganic solid electrolyte, such as a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or a solid polymer electrolyte. The solid electrolyte has been described above, and this solid electrolyte may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0101] Based on the total weight of the positive electrode active material layer, solid electrolyte can be included in an amount of 0.1 wt% to 35 wt% (e.g., 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%). In the positive electrode active material layer, based on the total weight of the positive electrode active material and solid electrolyte, positive electrode active material can be included in an amount of 65 wt% to 99 wt%, and solid electrolyte can be included in an amount of 1 wt% to 35 wt%, for example, positive electrode active material can be included in an amount of 80 wt% to 90 wt%, and solid electrolyte can be included in an amount of 10 wt% to 20 wt%. If solid electrolyte in amounts within the above ranges is included in the positive electrode, the efficiency and cycle life characteristics of the all-solid-state battery can be improved without degrading capacity. Based on a total of 100 wt% positive electrode active material layer, solid electrolyte can be included in an amount of 0.1 wt% to 30 wt%.

[0102] <Elastic Layer>

[0103] According to one embodiment, the all-solid-state battery may further include an elastic layer that buffers thickness variations that occur during charging and discharging. The elastic layer may be located between the negative electrode and the casing.

[0104] The elastic layer may include materials with an elastic recovery rate of 50% or greater and insulating properties, and may specifically include silicone rubber, acrylic rubber, fluororubber, nylon, synthetic rubber, or combinations thereof. The elastic material may be in the form of a polymer sheet.

[0105] Manufacturing of all-solid-state batteries

[0106] According to some embodiments, all-solid-state batteries can be manufactured by preparing a component including a negative electrode, a positive electrode, and a solid electrolyte layer located between the negative electrode and the positive electrode, and then pressing the component together.

[0107] Pressing can be performed at temperatures ranging from 25°C to 90°C. Pressing can be performed at pressures of 550 MPa or less (e.g., 500 MPa or less, or 1 MPa to 500 MPa). The pressing time can be varied depending on temperature, pressure, etc., and may be less than 30 minutes. Pressing can be performed using, for example, an isostatic press, roller press, plate press, or warm isostatic press (WIP).

[0108] All-solid-state secondary batteries can be unit cells with a structure including a positive electrode / solid electrolyte layer / negative electrode, dual cells with a structure including a positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or stacked cells in which unit cells are repeated.

[0109] All-solid-state rechargeable batteries have no shape limitations, but can be coin-shaped, push-button type, sheet type, laminate type, cylindrical type, or flat type, etc. Furthermore, all-solid-state rechargeable batteries can be used in large batteries used in electric vehicles, etc. For example, all-solid-state rechargeable batteries can also be used in hybrid vehicles (such as plug-in hybrid electric vehicles (PHEVs)). In addition, all-solid-state rechargeable batteries can be used in various applications requiring large-capacity energy storage, and for example, in electric bicycles or power tools. Furthermore, all-solid-state rechargeable batteries can be used in various fields such as portable electronic devices.

[0110] Figure 1 A cross-sectional view of an all-solid-state battery according to one embodiment is shown. (Reference) Figure 1 The all-solid-state battery 100 may have the following structure: an electrode assembly consisting of a negative electrode 400 including a negative electrode current collector 401 and a negative electrode coating 405, a solid electrolyte layer 300, and a positive electrode 200 including a positive electrode active material layer 203 and a positive electrode current collector 201 is housed in a casing (such as a bag). The all-solid-state battery 100 may further include an elastic layer 500 located on the outside of at least one of the positive electrode 200 and the negative electrode 400.

[0111] In addition, if the all-solid-state battery is charged, lithium ions are released from the positive electrode active material and deposited on the negative electrode current collector 401, thereby forming a lithium-containing layer (lithium deposition layer).

[0112] Figure 1 An electrode assembly including a negative electrode 400, a solid electrolyte layer 300, and a positive electrode 200 is shown, but all-solid-state batteries can also be manufactured by stacking at least two electrode assemblies. For example, electrode assemblies can be stacked in numbers such as 2 to 100, 3 to 50, or 4 to 20.

[0113] Figure 2 This schematically illustrates another embodiment of an all-solid-state battery. Figure 2The all-solid-state battery 100 shown includes a positive electrode 200 comprising a positive electrode current collector 201 and a positive electrode active material layer 203, a negative electrode 400 comprising a negative electrode current collector 401 and a negative electrode coating 403, a solid electrolyte 300 between the positive electrode 200 and the negative electrode 400, a battery casing 500 wherein these components are housed, and a lithium deposition layer 405' between the negative electrode current collector 401 and the negative electrode coating 403.

[0114] Methods of implementing the present invention

[0115] The following describes embodiments and comparative examples of the invention. However, these embodiments should not be construed as limiting the scope of the invention in any way.

[0116] (Example 1)

[0117] 1) Preparation of negative electrode

[0118] An adhesive solution is prepared by adding an adhesive in which polyacrylic acid and styrene-butadiene rubber are mixed in a weight ratio of 5:4 to an N-methylpyrrolidone solvent.

[0119] Carbon black with a primary particle size (D50) of approximately 30 nm and silver (Ag) with an average particle size (D50) of approximately 60 nm were added to a binder solution and mixed to prepare a negative electrode coating composition. Here, the amounts of binder, carbon black, and silver were used to achieve a weight ratio of 9:75:25.

[0120] The negative electrode is prepared by coating the negative electrode composition onto the nickel foil current collector using a doctor blade coater and then vacuum drying.

[0121] 85wt% LiNi 0.8 Co 0.15 Mn 0.05 The positive electrode composition is prepared by mixing O2 positive electrode active material, 13.5 wt% lithium sulfide silver germanite type solid electrolyte Li6PS5Cl, 1.0 wt% polyvinylidene fluoride binder and 0.5 wt% carbon nanotube conductive material in N-methylpyrrolidone solvent.

[0122] The positive electrode composition is coated onto an aluminum positive electrode current collector using a doctor blade coater, dried, and pressed to prepare the positive electrode.

[0123] (3) Preparation of solid electrolyte layer

[0124] The acrylate polymer of butyl acrylate was added to the binder solution of isobutyl isobutyrate (solid content: 50 wt%), which was then added to the sulfide-germanium sulfide solid electrolyte Li6PS5Cl and mixed with it. Here, the mixing ratio of solid electrolyte and binder was adjusted to have a weight ratio of 98.7:1.3.

[0125] The mixing process was performed using a Thinky mixer. 2 mm zirconia balls were added to the resulting mixture, and the mixture was stirred again using a Thinky mixer to prepare a slurry. The slurry was cast onto a release PTFE membrane and dried at room temperature to prepare a solid electrolyte layer with a thickness of 100 µm.

[0126] (4) Manufacturing of all-solid-state full-cell cells

[0127] A rechargeable all-solid-state battery cell is manufactured by sequentially stacking a negative electrode, a solid electrolyte layer, and a positive electrode and subjecting them to isostatic pressing at 380 MPa.

[0128] (Example 2)

[0129] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder in which polyacrylic acid and styrene-butadiene rubber were mixed in a weight ratio of 5:3 was used, and the amounts of binder, carbon black and silver were varied to have a weight ratio of 8:75:25.

[0130] (Example 3)

[0131] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder in which polyacrylic acid and styrene-butadiene rubber were mixed in a weight ratio of 5:2 was used, and the amounts of binder, carbon black and silver were varied to have a weight ratio of 7:75:25.

[0132] (Comparative Example 1)

[0133] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder solution prepared by adding a styrene-butadiene rubber binder to an N-methylpyrrolidone solvent was used.

[0134] (Comparative Example 2)

[0135] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder in which polyacrylic acid and styrene-butadiene rubber were mixed in a weight ratio of 5:1 was used, and the amounts of binder, carbon black and silver were varied to have a weight ratio of 6:75:25.

[0136] (Comparative Example 3)

[0137] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder in which polyacrylic acid and styrene-butadiene rubber were mixed in a 5:5 weight ratio was used, and the amounts of binder, carbon black and silver were varied to have a weight ratio of 10:75:25.

[0138] (Comparative Example 4)

[0139] All-solid-state battery cells were manufactured in the same manner as in Example 1, except that a binder in which a copolymer of polyvinyl alcohol and polyacrylic acid was mixed with styrene-butadiene rubber in a weight ratio of 5:4 was used.

[0140] The total amount of binder included in the negative electrode coatings of Examples 1 to 3 and Comparative Examples 1 to 4 is shown in Table 1.

[0141] Experiment Example 1) Evaluation of Resistance

[0142] The resistance (surface resistance) of the negative electrode according to Examples 1 to 3 and Comparative Examples 1 to 3 was measured using a four-probe method by probing 46 pins (XF057, manufactured by HIOKI), and the results are shown in Table 2.

[0143] Experimental Example 2) Measurement of Initial Coulomb Efficiency

[0144] The all-solid-state battery cells according to Examples 1 to 3 and Comparative Examples 1 to 4 were charged and discharged once at 0.1 C at 45°C. The discharge capacity / charge capacity ratio was calculated, and the results are shown in Table 1 as the initial coulombic efficiency.

[0145] Experiment Example 3) Measurement of Capacity Retention

[0146] The all-solid-state battery cells according to Examples 1 to 3 and Comparative Examples 1 to 3 were charged and discharged 100 times at 0.1 C at 45°C. The ratio of the capacity of the 100th discharge to the capacity of the 1st discharge was calculated. The results are shown in Table 1 as capacity retention.

[0147] Table 1

[0148]

[0149] As shown in Table 1, the all-solid-state battery cells according to Examples 1 to 3, comprising polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:2 to 5:4, exhibited low resistance, high initial coulombic efficiency, and excellent capacity retention.

[0150] On the other hand, Comparative Example 1, which consisted only of styrene-butadiene rubber, exhibited high resistance, resulting in reduced initial coulombic efficiency and capacity retention.

[0151] The all-solid-state battery cell of Comparative Example 2, which includes polyacrylic acid and styrene-butadiene rubber in a 5:1 weight ratio, has low resistance and high initial coulombic efficiency, but exhibits deteriorated cycle life characteristics.

[0152] The all-solid-state battery cell of Comparative Example 3, which includes polyacrylic acid and styrene-butadiene rubber in a 5:5 weight ratio, exhibits slightly improved cycle life characteristics, but has high resistance and low initial coulombic efficiency.

[0153] In Comparative Example 4, where polyvinyl alcohol-polyacrylic acid copolymer was used with styrene-butadiene rubber instead of polyacrylic acid, the resistance did not increase significantly compared to Example 1, but the coulombic efficiency and capacity retention decreased.

[0154] Although the invention has been described in conjunction with exemplary embodiments that are now considered practical, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the claims.

Claims

1. A negative electrode for an all-solid-state battery, comprising: The negative electrode coating includes a binder comprising polyacrylic acid and styrene-butadiene rubber in a weight ratio of 5:4 to 5:2; Carbon materials; And metals.

2. The negative electrode for an all-solid-state battery according to claim 1, wherein the amount of the binder is 6 wt% to 10 wt% based on a total of 100 wt% of the negative electrode coating.

3. The negative electrode for an all-solid-state battery according to claim 1, wherein the carbon material is crystalline carbon, amorphous carbon, or a combination thereof.

4. The negative electrode for an all-solid-state battery according to claim 1, wherein the carbon material is amorphous carbon.

5. The negative electrode for an all-solid-state battery according to claim 4, wherein the amorphous carbon is carbon black, acetylene black, superconducting acetylene black, Ketjen black, furnace black, activated carbon, graphene, or a combination thereof.

6. The negative electrode for an all-solid-state battery according to claim 1, wherein the metal is Ag, Au, Sn, Zn, Al, Mg, Ge, Cu, In, Ni, Bi, Pt, Pd or a combination thereof.

7. The negative electrode for an all-solid-state battery according to claim 1, wherein the metal is Ag.

8. The negative electrode for an all-solid-state battery according to claim 1, wherein the metal is loaded on the carbon-based material in the negative electrode coating.

9. The negative electrode for an all-solid-state battery according to claim 1, wherein the amount of the carbonaceous material is 55 wt% to 80 wt% based on a total of 100 wt% of the negative electrode coating.

10. The negative electrode for an all-solid-state battery according to claim 1, wherein the amount of the metal is 14wt% to 35wt% based on a total of 100wt% of the negative electrode coating.

11. The negative electrode for an all-solid-state battery according to claim 1, wherein the metal has a size of 5 nm to 800 nm.

12. An all-solid-state battery, comprising: The negative electrode according to any one of claims 1 to 11; Positive electrode; as well as A solid electrolyte layer is located between the positive electrode and the negative electrode.

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