All-solid rechargeable battery

Abstract

Provided is an all-solid rechargeable battery comprising a negative electrode, a positive electrode, and a solid electrolyte layer disposed between the negative electrode and the positive electrode, wherein the solid electrolyte layer comprises: a first solid electrolyte layer disposed in contact with the negative electrode and comprising a first solid electrolyte and a carbon composite; and a second solid electrolyte layer disposed in contact with the positive electrode and including a second solid electrolyte, the first solid electrolyte and the second solid electrolyte being in the form of particles, wherein the average particle diameter (D50) of the first solid electrolyte is less than the average particle diameter (D50) of the second solid electrolyte.

Description

All-solid-state secondary battery

[0001] It is about all-solid-state secondary batteries.

[0002] Lithium secondary batteries, which offer high energy density and portability, are primarily used as power sources for mobile information terminals such as mobile phones, laptops, and smartphones. Recently, active research is underway to utilize high-energy-density lithium secondary batteries as power sources for hybrid and electric vehicles, or as power storage devices.

[0003] Commercially available lithium secondary batteries use electrolytes containing flammable organic solvents, posing safety concerns that can lead to explosions or fires in the event of collisions, penetrations, or other problems. Therefore, all-solid-state secondary batteries, which utilize solid electrolytes instead of the conventional electrolytes, are being proposed. All-solid-state secondary batteries are composed entirely of solid materials, eliminating the risk of electrolyte leakage and explosion. Furthermore, they offer the advantage of being easy to manufacture in thinner forms.

[0004] An all-solid-state secondary battery is provided that can increase lithium ion conductivity and improve overall battery performance.

[0005] According to one embodiment, it comprises a cathode, an anode, and a solid electrolyte layer disposed between the cathode and the anode,

[0006] The above solid electrolyte layer is,

[0007] A first solid electrolyte layer is disposed in contact with the cathode and includes a first solid electrolyte and a carbon composite; and a second solid electrolyte layer is disposed in contact with the anode and includes a second solid electrolyte;

[0008] The above first solid electrolyte and the second solid electrolyte are in particle form, and an all-solid-state secondary battery is provided in which the average particle diameter (D50) of the first solid electrolyte is smaller than the average particle diameter (D50) of the second solid electrolyte.

[0009] An all-solid-state secondary battery according to one embodiment can exhibit improved battery performance by including a solid electrolyte having high lithium ion conductivity.

[0010] Figure 1 is a cross-sectional view schematically showing an all-solid-state secondary battery according to one embodiment.

[0011] Figure 2 is a cross-sectional view schematically showing an all-solid-state secondary battery according to another embodiment.

[0012] Below, specific implementation examples are described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in various different forms and is not limited to the implementation examples described herein.

[0013] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0014] Here, “combination of these” means a mixture, laminate, composite, copolymer, alloy, blend, reaction product, etc. of the components.

[0015] It should be understood that the terms "include," "comprising," or "having" herein are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0016] To clearly illustrate various layers and regions in the drawings, their thicknesses are enlarged, and similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" or "on" another element, this includes not only the case where it is "directly over" the other element, but also the case where there are other elements in between. Conversely, when an element is said to be "directly over" another element, it means that there are no other elements in between.

[0017] Also, here, “layer” includes not only the shape formed on the entire surface when observed in a plan view, but also the shape formed on a portion of the surface.

[0018] The average particle size can be measured by methods well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope image or a scanning electron microscope image. Alternatively, the average particle size can be obtained by measuring using dynamic light scattering, performing data analysis, counting the number of particles for each particle size range, and calculating from the counted number. Unless otherwise defined, the average particle size can mean the diameter (D50) of particles in a particle size distribution that have a cumulative volume of 50% by volume. In addition, unless otherwise defined, the average particle size can be obtained by randomly measuring the sizes (diameters or major axis lengths) of about 20 particles in a scanning electron microscope image to obtain a particle size distribution, and taking the diameter (D50) of particles in the particle size distribution that have a cumulative volume of 50% by volume as the average particle size.

[0019] Here, “or” is not interpreted in an exclusive sense, for example, “A or B” is interpreted to include A, B, A+B, etc.

[0020] “Metal” is interpreted as a concept that includes common metals, transition metals, and metalloids (semi-metals).

[0021] All-solid-state secondary battery

[0022] According to one embodiment, an all-solid-state secondary battery includes a negative electrode, a positive electrode, and a solid electrolyte layer disposed between the negative electrode and the positive electrode, wherein the solid electrolyte layer includes: a first solid electrolyte layer disposed in contact with the negative electrode and including a first solid electrolyte and a carbon composite; and a second solid electrolyte layer disposed in contact with the positive electrode and including a second solid electrolyte; wherein the first solid electrolyte and the second solid electrolyte are in the form of particles, and an average particle diameter (D50) of the first solid electrolyte is smaller than an average particle diameter (D50) of the second solid electrolyte.

[0023] Below, an all-solid-state secondary battery according to an implementation example is described with reference to FIG. 1.

[0024] Fig. 1 is a cross-sectional view of an all-solid-state secondary battery according to an embodiment. Referring to Fig. 1, an all-solid-state secondary battery (100) may have a structure in which an electrode assembly in which a negative electrode (400) including a negative electrode current collector (401) and a negative electrode active material layer (403), 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) are laminated is housed in a battery case.

[0025] The above-mentioned all-solid-state secondary battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400).

[0026] FIG. 1 illustrates one electrode assembly including a cathode (400), a solid electrolyte layer (300), and a cathode (200), but an all-solid-state secondary battery may be manufactured by stacking two or more electrode assemblies.

[0027] For example, the all-solid-state secondary battery may be a unit cell having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit cell is repeated.

[0028] The shape of the above-mentioned all-solid-state secondary battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. In addition, the above-mentioned all-solid-state secondary battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state secondary battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring a large amount of power storage, and for example, it can be used in electric bicycles or power tools, etc. In addition, the above-mentioned all-solid-state secondary battery can be used in various fields such as portable electronic devices.

[0029] solid electrolyte layer

[0030] In an all-solid-state secondary battery according to one embodiment, a solid electrolyte layer (300) includes a first solid electrolyte layer (310) disposed in contact with a negative electrode (400) and including a first solid electrolyte and a carbon composite; and a second solid electrolyte layer (320) disposed in contact with a positive electrode (200) and including a second solid electrolyte.

[0031] Here, the first solid electrolyte and the second solid electrolyte are each in the form of particles, and the average particle diameter (D50) of the first solid electrolyte is smaller than the average particle diameter (D50) of the second solid electrolyte.

[0032] By applying a first solid electrolyte having a relatively small average particle size to the first solid electrolyte layer (310) in contact with the negative electrode (400), pores can be reduced and conductive paths can be easily formed. In addition, by applying a second solid electrolyte having a relatively large average particle size to the second solid electrolyte layer (320) in contact with the positive electrode (200), ionic conductivity at the interface with the positive electrode and ionic conductivity within the solid electrolyte layer can be increased.

[0033] According to one embodiment, an all-solid-state secondary battery comprises a double-layered solid electrolyte layer. By controlling the particle size of the solid electrolyte contained in each solid electrolyte layer, the occurrence of non-contact regions between electrolyte particles can be minimized. Accordingly, the path through which lithium ions can move can be optimized, thereby increasing lithium ion conductivity and improving the overall characteristics of the battery.

[0034] For example, the average particle diameter (D50) of the first solid electrolyte may be 0.1 µm to 2.0 µm, for example, 0.1 µm to 1.5 µm, 0.1 µm to 1.0 µm, or 0.5 µm to 1.0 µm.

[0035] The average particle diameter (D50) of the second solid electrolyte may be 2.0 µm to 5.0 µm, for example, 2.0 µm to 4.0 µm, or 2.5 µm to 3.0 µm.

[0036] The average particle diameter (D50) of the first and second solid electrolytes may be measured from an electron microscope image, and for example, the particle size distribution may be obtained by measuring the size (diameter or length of the major axis) of about 20 particles in a scanning electron microscope image, and D50 may be calculated from this.

[0037] Meanwhile, the average particle diameter (D50) of each of the first solid electrolyte and the second solid electrolyte included in the solid electrolyte layer may be larger than the average particle diameter (D50) of the solid electrolyte included in the positive electrode (200). In this case, the energy density of the all-solid-state secondary battery can be maximized while the mobility of lithium ions can be increased, thereby improving the overall performance.

[0038] For example, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (200) may be 0.1 ㎛ to 1.9 ㎛, or 0.1 ㎛ to 1.0 ㎛, or 0.1 ㎛ to 0.5 ㎛. When this particle diameter range is satisfied, the energy density of the all-solid-state secondary battery can be maximized while the transfer of lithium ions is facilitated, thereby suppressing resistance and thus improving the overall performance of the all-solid-state secondary battery.

[0039] The first solid electrolyte layer (310) comprises a carbon composite. This carbon composite is a material capable of enhancing lithium ion conductivity by enhancing conductivity. By including this carbon composite in the first solid electrolyte layer, which is positioned in contact with the negative electrode, the phenomenon of conductive path disconnection after charge / discharge cycles can be prevented, and battery performance, such as high capacity and high efficiency, can be improved.

[0040] The above carbon composite includes a carbon-based material and metal particles, and may be in a composite form in which the metal particles are dispersed within the carbon-based material, between the carbon-based materials, on the surface of the carbon-based material, or in two or more of these locations. For example, a metal may be supported on the carbon-based material.

[0041] The carbonaceous material may include amorphous carbon, crystalline carbon, or a mixture thereof. The amorphous carbon may include carbon black, vapor-grown carbon fibers (VGCF), acetylene black (AB), activated furnace black, or a combination thereof. The crystalline carbon may include natural graphite, artificial graphite, carbon nanotubes (CNTs), graphene, or a combination thereof. The crystalline carbon may be amorphous, plate-shaped, flake-shaped, spherical, or fibrous.

[0042] The metal particles may include silicon, silver, zinc, tin or a combination thereof.

[0043] Based on the total weight of the carbon-based material and the metal particles, the content of the metal particles may be 5 wt% to 40 wt%, and the content of the carbon-based material may be 60 wt% to 95 wt%. Within this range, the metal may be evenly dispersed in the carbon-based material and well composited.

[0044] The carbon composite may be included in an amount of 1 wt% to 20 wt% based on the total weight of the first solid electrolyte layer, for example, 5 wt% to 20 wt%, or 5 wt% to 10 wt%. When the above range is satisfied, the lithium ion conductivity can be significantly improved by minimizing the section where contact between solid electrolyte particles does not occur while improving conductivity.

[0045] The types of the first solid electrolyte and the second solid electrolyte are not particularly limited, and may be the same or different.

[0046] Even if the types of the first solid electrolyte and the second solid electrolyte are the same, the average particle diameter (D50) may be different due to differences in monomers or compositions, and the application is possible regardless as long as the average particle diameter of the first solid electrolyte is smaller than the average particle diameter of the second solid electrolyte.

[0047] The first solid electrolyte and the second solid electrolyte may each independently be an inorganic solid electrolyte such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte, or a solid polymer electrolyte.

[0048] The above solid electrolyte may be a sulfide-based solid electrolyte having excellent ion conductivity, an oxide-based inorganic solid electrolyte, or a combination thereof.

[0049] The above sulfide-based solid electrolyte is, for example, Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, 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, Li2S-P2S5-Z m S n (m and n are integers, respectively, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In).

[0050] The above sulfide-based solid electrolyte may be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or a molar ratio of 50:50 to 80:20. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0051] Methods for mixing sulfur-containing raw materials for manufacturing sulfide-based solid electrolytes can be either mechanical milling or solution milling. Mechanical milling involves placing the starting materials in a reactor and vigorously stirring them with a ball mill or similar device to finely atomize and mix them. Using the solution mill, the starting materials are mixed in a solvent to produce a solid electrolyte as a precipitate. Furthermore, calcination can be performed after mixing. This additional calcination can further solidify the crystals of the solid electrolyte.

[0052] For example, the solid electrolyte may be an argyrodite-type sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be, for example, Li a M b P c S d A e (a, b, c, d and e are all 0 or more and 12 or less, M is Ge, Sn, Si or a combination thereof, and A is one of F, Cl, Br, or I), and specifically Li3PS4, Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, etc. These sulfide-based solid electrolytes have an ionic conductivity of 10, which is the ionic conductivity of a typical liquid electrolyte at room temperature. -4 10 inland -2 Because it possesses a high ionic conductivity approaching the S / cm range, it can form a close bond between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity, and further, it can form a close interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0053] The above sulfide-based solid electrolyte may be amorphous or crystalline, or may be a mixture of the two.

[0054] The above oxide-based inorganic solid electrolyte is, 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 (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La y TiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or mixtures thereof.

[0055] Meanwhile, each of the first solid electrolyte layer and the second solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0056] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt may improve ion conductivity by enhancing the lithium ion mobility of the solid electrolyte layer.

[0057] The above lithium salts include, 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(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0058] In addition, the lithium salt may be an imide-based lithium salt, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0059] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0060] The above ionic liquid may be a compound including a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) one or more anions selected from BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, Cl-, Br-, I-, BF4-, SO4-, CF3SO3-, (FSO2)2N-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, and (CF3SO2)2N-.

[0061] The ionic liquid may be at least one selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0062] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid may be 0.1:99.9 to 90:10, for example, 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 satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state secondary battery can be improved.

[0063] The thickness of the first solid electrolyte layer (310) and the thickness of the second solid electrolyte layer (320) may be the same or different. For example, the thickness of the first solid electrolyte layer and the thickness of the second solid electrolyte layer may be substantially the same. The thickness of the first solid electrolyte layer may be 10 μm to 200 μm, for example, 10 μm to 150 μm, 10 μm to 100 μm, or 20 μm to 80 μm. The thickness of the second solid electrolyte layer may be 10 μm to 200 μm, for example, 10 μm to 150 μm, 10 μm to 100 μm, or 20 μm to 80 μm.

[0064] The above solid electrolyte layer (300) may be in the form of a free-standing film. A free-standing film may mean one that can maintain its shape on its own without a separate support structure (e.g., a substrate such as a film or glass).

[0065] The above self-supporting membrane-type solid electrolyte layer can be manufactured by coating first and second solid electrolyte layers on a release film, laminating and pressing the first and second solid electrolyte layers so that they are in contact, and then removing the release film.

[0066] anode

[0067] In one embodiment, the device includes a positive electrode current collector (201) and a positive electrode active material layer (203) positioned on the positive electrode current collector, wherein the positive electrode active material layer (203) includes a positive electrode active material and a solid electrolyte, and may optionally include a binder and / or a conductive material. In this case, the second solid electrolyte layer described above may be referred to as a surface in contact with the positive electrode active material layer (203).

[0068] The above-mentioned positive electrode active material can be applied without limitation as long as it is generally used in all-solid-state secondary batteries. For example, the above-mentioned positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0069] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0070] Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0071] Li a E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0072] Li a E 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0073] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0074] Li a Ni 1-b-c Co b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α <2);

[0075] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0076] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0077] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0078] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0079] Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0080] Li a Ni b Co c Mr d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0081] Li a NiG bO2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0082] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0083] Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0084] Li a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0085] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0086] QO2; QS2; LiQS2;

[0087] V2O5; LiV2O5;

[0088] LiZO2;

[0089] LiNiVO4;

[0090] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0091] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0092] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0093] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0094] The positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate oxide (LFP).

[0095] The positive electrode active material may include, for example, a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, a cobalt-free lithium nickel-manganese-based oxide represented by the following chemical formula 4, or a combination thereof.

[0096] [Chemical Formula 1]

[0097] Li a1 Ni x1 M 1 y1 M 2 z1 O 2-b1 X b1

[0098] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, 0≤z1≤0.7, 0.9≤x1+y1+z1≤1.1, and 0≤b1≤0.1, and M 1 and M 2 are each independently one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Fe, Mg, Mn, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0099] In the above chemical formula 1, 0.6≤x1≤1, 0≤y1≤0.4, and 0≤z1≤0.4, or 0.8≤x1≤1, 0≤y1≤0.2, and 0≤z1≤0.2.

[0100] [Chemical Formula 2]

[0101] Li a2 Co x2 M 3 y2 O 2-b2 X b2

[0102] In the above chemical formula 2, 0.9≤a2≤1.8, 0.7≤x2≤1, 0≤y2≤0.3, 0.9≤x2+y2≤1.1, and 0≤b2≤0.1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0103] [Chemical Formula 3]

[0104] Li a3 Fe x3 M 4 y3 PO 4-b3 X b3

[0105] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, 0≤y3≤0.4, and 0≤b3≤0.1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, Mg, Mn, Mo, Ni, Se, Si, Sn, Sr, Ti, V, W, Y, Zn and Zr, and X is one or more elements selected from the group consisting of F, P and S.

[0106] [Chemical Formula 4]

[0107] Li a4 Ni x4 Mn y4 M 5 z4 O 2-b4 X b4

[0108] In the above chemical formula 4, 0.9≤a2≤1.8, 0.8≤x4<1, 0 <y4≤0.2, 0≤z4≤0.2, 0.9≤x4+y4+z4≤1.1, 및 0≤b4≤0.1이고 M 5 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, Mg, Mo, Nb, Si, Sn, Sr, Ti, V, W, and Zr, and X is one or more elements selected from the group consisting of F, P, and S.

[0109] The average particle diameter (D50) of the positive electrode active material may 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.

[0110] For example, the positive electrode active material may include small particles having an average particle diameter (D50) of 1 μm to 9 μm and large particles having an average particle diameter (D50) of 10 μm to 25 μm. Here, the mixing ratio of the small particles and the large particles may be a weight ratio of about 10:90 to 40:60. A positive electrode active material having such a particle diameter range can be harmoniously mixed with other components within a positive electrode active material layer and can realize high capacity and high energy density.

[0111] Here, the average particle diameter may be obtained by selecting 20 or so random particles from a scanning electron microscope image of the positive electrode active material, measuring their particle diameters (diameter, or major axis, or major axis length), obtaining a particle size distribution, and then taking the diameter (D50) of particles having a cumulative volume of 50% by volume from the particle size distribution as the average particle diameter.

[0112] The above-mentioned positive electrode active material may be in the form of a secondary particle formed by agglomeration of a plurality of primary particles, or may be in the form of a single particle. In addition, the above-mentioned positive electrode active material may be spherical or nearly spherical in shape, or may be polyhedral or irregular in shape.

[0113] The positive electrode active material may be included in an amount of 55 wt% to 99 wt% based on 100 wt% of the positive electrode active material layer, for example, 65 wt% to 95 wt%, or 75 wt% to 91 wt%.

[0114] The solid electrolyte included in the positive electrode active material layer may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof, and may be, for example, an argyrodite-type sulfide-based solid electrolyte. Since the solid electrolyte has been described above, a detailed description thereof will be omitted.

[0115] With respect to 100 wt% of the above positive electrode active material layer, the solid electrolyte may be included in an amount of 0.1 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%.

[0116] In addition, in the positive electrode active material layer, 65 to 99 wt% of the positive electrode active material and 1 to 35 wt% of the solid electrolyte may be included based on the total weight of the positive electrode active material and the solid electrolyte, for example, 80 to 90 wt% of the positive electrode active material and 10 to 20 wt% of the solid electrolyte may be included. When the solid electrolyte is included in the positive electrode in such an amount, the efficiency and life characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0117] The above binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector, and representative examples thereof include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0118] The content of the binder in the positive electrode active material layer may be approximately 0.1 wt% to 5 wt% based on 100 wt% of the positive electrode active material layer. Within the above content range, the binder can sufficiently exhibit adhesive ability without deteriorating battery performance.

[0119] The above-described positive electrode active material layer may further include a conductive material. The conductive material is used to provide conductivity to the electrode, and any material that does not cause a chemical change and is electronically conductive in the battery to be formed may be used. Examples of conductive materials that may be used include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials containing copper, nickel, aluminum, silver, etc. in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0120] The content of the conductive material in the positive electrode active material layer may be 0 wt% to 3 wt%, 0.01 wt% to 2 wt%, or 0.1 wt% to 1 wt%, based on 100 wt% of the positive electrode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0121] Aluminum foil may be used as the positive electrode current collector, but is not limited thereto.

[0122] cathode

[0123] An anode (400) for an all-solid-state secondary battery includes a cathode current collector (401) and a cathode active material layer (403) positioned on the cathode current collector (401). The cathode active material layer includes a cathode active material and may further include a binder and / or a conductive material. In this case, the first solid electrolyte layer (310) described above may be referred to as a surface in contact with the cathode active material layer (403).

[0124] The above-mentioned positive electrode active material can be applied without limitation as long as it is generally used in all-solid-state secondary batteries. For example, the above-mentioned negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0125] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0126] As the above lithium metal alloy, an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0127] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and the Si-based negative electrode active material may be silicon, a silicon-carbon composite, or SiO. x(0 < x < 2), Si-Q alloy (wherein Q is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Si), Sn-based negative electrode active materials include Sn, SnO2, Sn-R alloy (wherein R is an element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, and is not Sn), and at least one of these may be mixed with SiO2 for use. The above elements Q and R may be selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.

[0128] For example, the negative active material may include silicon-carbon composite particles. The average particle diameter (D50) of the silicon-carbon composite particles may be, for example, 0.5 μm to 20 μm. The average particle diameter (D50) is measured by a particle size analyzer and refers to the diameter of particles having a cumulative volume of 50% by volume in a particle size distribution. With respect to 100 wt% of the silicon-carbon composite particles, silicon may be included in an amount of 10 wt% to 60 wt% and carbon may be included in an amount of 40 wt% to 90 wt%. The silicon-carbon composite particles may include, for example, a core including silicon particles and a carbon coating layer positioned on a surface of the core. The average particle diameter (D50) of the silicon particles in the core may be, for example, 10 nm to 1 μm, or 10 nm to 200 nm. The silicon particles may exist as silicon alone, in the form of a silicon alloy, or in an oxidized form. The oxidized form of silicon is SiO x (0 <x<2)로 표시될 수 있다. 또한, 상기 탄소 코팅층의 두께는 약 5 nm 내지 100 nm일 수 있다.

[0129] For example, the silicon-carbon composite particle may include a core including silicon particles and crystalline carbon, and a carbon coating layer located on the surface of the core and including amorphous carbon. For example, in the silicon-carbon composite particle, the amorphous carbon may not be present in the core but may be present only in the carbon coating layer. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof, and the amorphous carbon may be formed from coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or a polymer resin (phenol resin, furan resin, polyimide resin, etc.). At this time, the content of the crystalline carbon may be 10 wt% to 70 wt%, and the content of the amorphous carbon may be 20 wt% to 40 wt% with respect to 100 wt% of the silicon-carbon composite particle.

[0130] In the above silicon-carbon composite particle, the core may include a void in the central portion. The radius of the void may be 30% to 50% of the radius of the silicon-carbon composite particle.

[0131] The silicon-carbon composite particles described above can effectively suppress problems such as volume expansion, structural collapse, or particle crushing due to charge and discharge, thereby preventing the phenomenon of conductive path disconnection, realizing high capacity and high efficiency, and are advantageous for use under high voltage or fast charging conditions.

[0132] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material. When the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material are used in combination, the mixing ratio can be 1:99 to 90:10 by weight.

[0133] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0134] In one embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. In addition, when the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0135] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may be an insoluble binder, a water-soluble binder, or a combination thereof.

[0136] The above-mentioned non-aqueous binder may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer containing ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0137] The water-soluble binder may be a rubber-based binder or a polymer resin binder. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0138] When a water-soluble binder is used as the negative electrode binder, a cellulose-based compound capable of imparting viscosity as a type of thickener may be further included. The cellulose-based compound may be a mixture of one or more of carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, or an alkali metal salt thereof. The alkali metal may be Na, K, or Li. The amount of the thickener used may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0139] The above conductive material is used to provide conductivity to the electrode, and in the battery to be formed, any material that does not cause a chemical change and is electronically conductive can be used. Examples of conductive materials that can be used include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials including copper, nickel, aluminum, silver, etc. and in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; or conductive materials including mixtures thereof.

[0140] The negative electrode current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.

[0141] As another example, the negative electrode for an all-solid-state secondary battery may be a precipitation-type negative electrode. The precipitation-type negative electrode may refer to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which lithium metal or the like is precipitated or deposited on the negative electrode when the battery is charged, and this acts as a negative electrode active material.

[0142] Fig. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation-type negative electrode. Referring to Fig. 2, the precipitation-type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) positioned on the current collector. An all-solid-state secondary battery including such a precipitation-type negative electrode (400') starts initial charging in a state in which no negative electrode active material is present, and during charging, high-density lithium metal is precipitated or deposited between the current collector (401) and the negative electrode coating layer (405) or on the negative electrode coating layer (405) to form a lithium metal layer (404), which may function as a negative electrode active material. Accordingly, in an all-solid-state secondary battery that has been charged more than once, the precipitation-type negative electrode (400') may include, for example, a current collector (401), a lithium metal layer (404) positioned on the current collector, and a negative electrode coating layer (405) positioned on the metal layer. The lithium metal layer (404) refers to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may be referred to as a metal layer, a lithium layer, a lithium deposition layer, or a negative electrode active material layer.

[0143] In this case, the first solid electrolyte layer (310) can be said to be a surface in contact with the cathode coating layer (405).

[0144] The above cathode coating layer (405) may be referred to as a lithium electrodeposition induction layer or a cathode catalyst layer, and may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0145] The metal may be a lithium-philic metal, and may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one type of these or may be composed of several types of alloys. When the metal is present in the form of particles, the average particle diameter (D50) thereof may be about 4 μm or less, and may be, for example, 10 nm to 4 μm.

[0146] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0147] When the above-described negative electrode coating layer (405) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state secondary battery can be improved. The above-described negative electrode coating layer (405) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0148] The above-described cathode coating layer (405) may include, for example, the above-described lithium-philic metal and amorphous carbon, in which case the precipitation of the lithium metal may be effectively promoted. As a specific example, the cathode coating layer (405) may include a composite in which a lithium-philic metal is supported on amorphous carbon.

[0149] The above cathode coating layer (405) may further include a binder, and the binder may be, for example, a conductive binder. In addition, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0150] The thickness of the cathode coating layer (405) may be, for example, 100 nm to 20 ㎛, or 500 nm to 10 ㎛, or 1 ㎛ to 5 ㎛.

[0151] The above-described precipitated negative electrode (400') may further include, for example, a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one type thereof or may be composed of multiple types of alloys. The thin film may further planarize the precipitated form of the lithium metal layer (404) and further improve the characteristics of the all-solid-state secondary battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0152] The lithium metal layer (404) may include lithium metal or a lithium alloy. The lithium alloy may be, for example, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, or a Li-Si alloy.

[0153] The thickness of the lithium metal layer (404) may be 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the lithium metal layer (404) is too thin, it may be difficult to perform the role of a lithium storage, and if it is too thick, the battery volume may increase and performance may deteriorate.

[0154] When such a precipitation-type cathode is applied, the cathode coating layer (405) can play a role in protecting the lithium metal layer (404) and suppressing the precipitation growth of lithium deadlight. Accordingly, short-circuiting and capacity reduction of the all-solid-state battery can be suppressed, and the life characteristics can be improved.

[0155] Hereinafter, examples and comparative examples of the present invention are described. The following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0156] [Example]

[0157] Example 1

[0158] 1. Manufacturing of the cathode

[0159] An Ag / C composite is prepared by mixing carbon black having a primary particle size (D50) of about 30 nm and silver (Ag) having an average particle size (D50) of about 60 nm in a weight ratio of 3:1, and 0.25 g of the composite is added to 2 g of an NMP solution containing 7 wt% of polyvinylidene fluoride binder and mixed to prepare a negative electrode coating layer composition. This is applied to a SUS current collector using a bar coater, vacuum-dried, and then rolled to prepare a deposition-type negative electrode having a negative electrode coating layer formed on the current collector.

[0160] 2. Manufacturing of the anode

[0161] LiNi coated with Li2O-ZrO2 0.9 Co 0.05 Mn 0.05 A positive electrode composition is prepared by mixing 85 wt% of an O2 positive electrode active material, 13.5 wt% of an argyrodite-type solid electrolyte (Li6PS5Cl), 1.0 wt% of a PVdF binder, and 0.5 wt% of a carbon nanotube conductive material in an OA solvent. The prepared positive electrode composition is coated on a positive electrode current collector using a bar coater and vacuum-dried, thereby preparing a positive electrode having a positive electrode active material layer formed on the current collector.

[0162] 3. Manufacturing of solid electrolyte layer

[0163] A first solid electrolyte (Li6PS5Cl, Mitsui Co., Ltd.), a carbon composite (Denka Black, Denka Co., Ltd.), and a dispersant having an average particle diameter of about 1 μm are added to a binder solution in which an acrylic binder is dissolved in an octyl acetate (OA) solvent, and stirred to prepare a first solid electrolyte layer slurry. The first solid electrolyte layer slurry contains 92 wt% of the first solid electrolyte, 6 wt% of the carbon composite, 1.3 wt% of the binder, and 0.7 wt% of the dispersant. The prepared first solid electrolyte layer slurry is cast on a polyethylene terephthalate (PET) release film to a thickness of about 50 μm and dried at room temperature to prepare a first solid electrolyte layer.

[0164] A second solid electrolyte layer slurry is prepared by adding a second solid electrolyte (Li6PS5Cl, Mitsui) having an average particle diameter of about 3 μm and a dispersant to a binder solution in which an acrylic binder is dissolved in an octyl acetate (OA) solvent and stirring the mixture. The second solid electrolyte layer slurry contains 98 wt% of the second solid electrolyte, 1.3 wt% of the binder, and 0.7 wt% of the dispersant. The prepared second solid electrolyte layer slurry is cast on a polyethylene terephthalate (PET) release film with a thickness of about 50 μm and dried at room temperature to prepare a second solid electrolyte layer.

[0165] 4. Manufacturing of all-solid-state secondary batteries

[0166] A first solid electrolyte layer is laminated on the negative electrode so that the negative active material layer of the manufactured negative electrode is in contact with the first solid electrolyte layer. A second solid electrolyte layer is laminated on the first solid electrolyte layer. A positive electrode is laminated on the second solid electrolyte layer so that the second solid electrolyte layer is in contact with the positive active material layer.

[0167] An assembly in which a cathode, a first solid electrolyte layer, a second solid electrolyte layer, and a cathode are sequentially laminated is inserted into a pouch, sealed, and subjected to a warm isostatic press (WIP) at a high temperature of 85°C and 500 MPa for 30 minutes to manufacture an all-solid-state secondary battery.

[0168] In the manufactured all-solid-state secondary battery, the thickness of each of the first solid electrolyte layer and the second solid electrolyte layer is about 40 μm.

[0169] Example 2

[0170] An all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that the average particle size of the first solid electrolyte included in the first solid electrolyte layer is about 2 μm.

[0171] Example 3

[0172] An all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that the average particle size of the second solid electrolyte included in the second solid electrolyte layer is about 2 μm.

[0173] Comparative Example 1

[0174] An all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that the first solid electrolyte layer does not include a carbon composite, and the first solid electrolyte layer slurry is manufactured to include 98 wt% of the first solid electrolyte, 1.3 wt% of a binder, and 0.7 wt% of a dispersant.

[0175] Comparative Example 2

[0176] An all-solid-state secondary battery is manufactured in the same manner as in Example 2, except that the first solid electrolyte layer does not include a carbon composite, and the first solid electrolyte layer slurry is manufactured to include 98 wt% of the first solid electrolyte, 1.3 wt% of a binder, and 0.7 wt% of a dispersant.

[0177] Comparative Example 3

[0178] An all-solid-state secondary battery is manufactured in the same manner as in Example 3, except that the first solid electrolyte layer does not include a carbon composite, and the first solid electrolyte layer slurry is manufactured to include 98 wt% of the first solid electrolyte, 1.3 wt% of a binder, and 0.7 wt% of a dispersant.

[0179] First solid electrolyte layerSecond solid electrolyte layerFirst solid electrolyte (average particle size)Presence or absence of carbon complexSecond solid electrolyte (average particle size)Example 1Li6PS5Cl (1㎛)YesLi6PS5Cl (3㎛)Example 2Li6PS5Cl (2㎛)YesLi6PS5Cl (3㎛)Example 3Li6PS5Cl (1㎛)YesLi6PS5Cl (2㎛)Comparative example 1Li6PS5Cl (1㎛)NoLi6PS5Cl (3㎛)Comparative example 2Li6PS5Cl (2㎛)NoLi6PS5Cl (3㎛)Comparative example 3Li6PS5Cl (1㎛)NoLi6PS5Cl (2㎛)

[0180] Experimental Example: Initial Charge-Discharge Characteristics

[0181] For the all-solid-state secondary batteries manufactured in Examples 1 to 3 and Comparative Examples 1 to 3, when charged at a constant current of 0.1 C at 45°C to an upper limit voltage of 4.25 V, then charged at a constant voltage until a current of 0.05 C was reached, and discharged at 0.1 C to an end voltage of 2.5 V, the charge amount and discharge amount of each battery are shown in Table 2 below.

[0182] Additionally, the ratio (%) of the discharge amount to the charge amount is calculated as the charge / discharge efficiency and is shown in Table 2 below.

[0183] Charge capacity (mAh / g)Discharge capacity (mAh / g)Charge / discharge efficiency (%)Example 1242.7209.586.3Example 2241.8208.086.0Example 3247.0206.683.6Comparative example 1242.5206.885.2Comparative example 2242.0207.785.8Comparative example 3244.2190.878.1

[0184] Referring to Table 2, it can be confirmed that the same level of initial charge / discharge performance is achieved in the all-solid-state secondary batteries of the examples and comparative examples.

[0185] Although the preferred embodiments have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts defined in the following claims also fall within the scope of the present invention.

[0186]

[0187]

[0188]

[0189] <Explanation of symbols>

[0190] 100: All-solid-state battery

[0191] 200: Bipolar

[0192] 201: Positive current collector

[0193] 203: Positive active material layer

[0194] 300: Solid electrolyte layer

[0195] 310: First solid electrolyte layer

[0196] 320: Second solid electrolyte layer

[0197] 400: Cathode

[0198] 401: Negative current collector

[0199] 403: Negative active material layer

[0200] 400': Precipitation cathode

[0201] 404: Lithium metal layer

[0202] 405: Cathode coating layer

[0203] 500: Elastic layer

Claims

1. Comprising a cathode, an anode, and a solid electrolyte layer disposed between the cathode and the anode, The above solid electrolyte layer is, A first solid electrolyte layer disposed in contact with the cathode and including a first solid electrolyte and a carbon composite; and a second solid electrolyte layer disposed in contact with the anode and including a second solid electrolyte; An all-solid-state secondary battery, wherein the first solid electrolyte and the second solid electrolyte are in particle form, and the average particle diameter (D50) of the first solid electrolyte is smaller than the average particle diameter (D50) of the second solid electrolyte.

2. In paragraph 1, An all-solid-state secondary battery, wherein the average particle diameter (D50) of the first solid electrolyte is 0.1 ㎛ to 2.0 ㎛.

3. In paragraph 1, An all-solid-state secondary battery, wherein the average particle diameter (D50) of the second solid electrolyte is 2.0 ㎛ to 5.0 ㎛.

4. In paragraph 1, An all-solid-state secondary battery, wherein the positive electrode includes a solid electrolyte, and the average particle diameter (D50) of the solid electrolyte is 0.1 ㎛ to 0.5 ㎛.

5. In paragraph 1, The above carbon composite is an all-solid-state secondary battery comprising a carbon-based material and metal particles.

6. In paragraph 5, An all-solid-state secondary battery, wherein the carbon-based material comprises amorphous carbon, crystalline carbon, or a mixture thereof.

7. In paragraph 5, An all-solid-state secondary battery, wherein the metal particles include silicon, silver, zinc, tin or a combination thereof.

8. In paragraph 5, Based on the total weight of the above carbon-based material and the above metal particles, An all-solid-state secondary battery, wherein the content of the carbon-based material is 60 to 95 wt%, and the content of the metal particles is 5 to 40 wt%.

9. In paragraph 1, An all-solid-state secondary battery, wherein the carbon composite is included in an amount of 1 to 20 wt% based on the total weight of the first solid electrolyte layer.

10. In paragraph 1, The thickness of the first solid electrolyte layer is 10 ㎛ to 200 ㎛, An all-solid-state secondary battery, wherein the thickness of the second solid electrolyte layer is 10 ㎛ to 200 ㎛.

11. In paragraph 1, An all-solid-state secondary battery, wherein the first solid electrolyte and the second solid electrolyte are sulfide-based solid electrolytes.

12. In Article 11, An all-solid-state secondary battery, wherein the above sulfide-based solid electrolyte includes an argyrodite-type sulfide.

13. In paragraph 1, The above negative electrode comprises a current collector and a negative electrode coating layer positioned on the current collector and containing a lithium-philic metal, a carbon material, or a combination thereof, An all-solid-state secondary battery comprising a lithium metal layer formed by charging between the above-described collector and the negative electrode coating layer.

14. In paragraph 1, The above positive electrode comprises a current collector and a positive electrode active material layer positioned on the current collector and containing a positive electrode active material, An all-solid-state secondary battery wherein the positive electrode active material comprises lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese oxide, lithium nickel manganese oxide, lithium manganese oxide, lithium iron phosphate oxide, or a combination thereof.

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