Positive electrode for all-solid-state battery and all-solid-state battery including the same

Abstract

The present invention relates to a positive electrode for an all-solid-state battery, and the positive electrode for an all-solid-state battery includes a positive electrode layer containing a sulfide-based solid electrolyte as a positive electrode active material, which is solid at room temperature and liquid at 60°C or higher, a plasticizer, and a lithium salt, and a current collector supporting the positive electrode layer.

Description

[Technical Field]

[0001] The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same. [Background technology]

[0002] Recently, with the rapid spread of battery-powered electronic devices such as mobile phones, laptops, and electric vehicles, the demand for small, lightweight, and relatively high-capacity secondary batteries has been growing rapidly. In particular, lithium secondary batteries have attracted attention as a power source for portable devices due to their light weight and high energy density. As a result, research and development efforts to improve the performance of lithium secondary batteries have been actively pursued.

[0003] Among lithium secondary batteries, all-solid-state batteries are batteries that are made entirely of solid materials, particularly those that use a solid electrolyte. Such all-solid-state batteries have the advantages of being safe because there is no risk of electrolyte leakage, and they can be easily fabricated into thin batteries.

[0004] Although attempts have been made to add lithium salts to electrodes or electrolytes in lithium-ion batteries to improve ionic conductivity and high-rate performance, it is difficult to add lithium salts to electrodes or electrolytes in all-solid-state batteries because lithium salts are insoluble in non-polar or low-polarity solvents used in the manufacture of electrodes or solid electrolytes for all-solid-state batteries. Summary of the Invention [Problem to be solved by the invention]

[0005] One embodiment provides a cathode for an all-solid-state battery that exhibits excellent electrochemical performance.

[0006] Another embodiment provides an all-solid-state battery including the positive electrode. [Means for solving the problem]

[0007] One embodiment provides a positive electrode for an all-solid-state battery, including a positive electrode layer including a positive electrode active material, a sulfide-based solid electrolyte, a plasticizer that is solid at room temperature and liquid at 60°C or higher, and a lithium salt, and a current collector that supports the positive electrode layer.

[0008] The lithium salt may be present in a solvated form within the plasticizer.

[0009] The plasticizer may be succinonitrile, ethylene carbonate, cyclic phosphate, polycaprolactone, polyethylene glycol (or polyethylene oxide), polytetrahydrofuran (or poly(tetramethylene ether glycol)), or a combination thereof.

[0010] The content of the plasticizer may be 0.05 to 5% by weight based on 100% by weight of the total positive electrode layer.

[0011] The lithium salts include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SOCF), LiCl, LiBr, LiClO, LiBF, LiB 10 Cl 10, LiFP6, LiAsF6, LiSbF6, LiAlCl4, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiF, LiI, LiB(C2O4)2, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiCF3SO3, or combinations thereof.

[0012] The content of the lithium salt may be 0.01 to 5% by weight based on 100% by weight of the entire positive electrode layer.

[0013] The sulfide-based solid electrolyte may be an ajilodite-type sulfide-based solid electrolyte.

[0014] Another embodiment provides an all-solid-state battery comprising the positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0015] The negative electrode includes a current collector and a negative electrode layer disposed on the current collector. The negative electrode layer may include lithium metal.

[0016] The negative electrode layer may include amorphous carbon and a metal, and the negative electrode may further include a lithium deposition layer after charging. [Effects of the Invention]

[0017] The positive electrode for an all-solid-state battery according to one embodiment can provide an all-solid-state battery with improved ionic conductivity and high-rate characteristics. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating a charge / discharge state of an all-solid-state battery according to an embodiment. FIG. [Figure 2] FIG. 1 is a schematic cross-sectional view showing a state after charging an all-solid-state battery according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the present invention is provided by way of example only and is not intended to limit the scope of the present invention, which is defined solely by the claims that follow.

[0020] Unless otherwise specified in this specification, when a layer, film, region, plate, or other part is said to be "on" another part, this includes not only when it is "directly on" the other part, but also when there is another part in between.

[0021] In the present invention, "particle size" or "particle diameter" may refer to an average particle diameter. The average particle diameter may be defined as the average particle diameter (D50) at 50% of the cumulative volume on a particle size distribution curve. The particle diameter may be measured by electron microscopy (SEM) or field emission scanning electron microscopy (FE-SEM), or by a laser diffraction method. Specifically, when measuring by the laser diffraction method, particles to be measured are dispersed in a dispersion medium, introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac MT3000), and irradiated with ultrasonic waves of about 28 kHz at an output of 60 W. The average particle diameter (D50) at 50% of the particle size distribution measured by the analyzer can then be calculated.

[0022] According to one embodiment, a positive electrode for an all-solid-state battery includes a positive electrode layer and a current collector supporting the positive electrode layer. The positive electrode layer includes a sulfide-based solid electrolyte, a plasticizer, and a lithium salt.

[0023] In one embodiment, the plasticizer is a solid at room temperature and a liquid at 60°C or higher. In another embodiment, "a liquid at 60°C or higher" refers to a reference pressure of 1 atmosphere (atm). The plasticizer is a material that changes state depending on temperature. Specifically, the plasticizer is a material that is solid at room temperature and liquid at 60°C or higher. This prevents reaction with the solid electrolyte at room temperature and easily dissolves lithium salt at high temperatures. Furthermore, under elevated temperature conditions, such as during rolling and drying processes, the plasticizer liquefies and can fully fill voids that may exist in the positive electrode layer. When the battery temperature is lowered to room temperature, the plasticizer transforms back into a solid, particularly a soft, glassy solid, thereby further promoting lithium ion migration and maintaining the physical properties of the positive electrode.

[0024] If a substance that does not change state depending on temperature, for example, a substance that is in a liquid state at room temperature and at high temperatures, is used as a plasticizer, it may react with the solid electrolyte, which may deteriorate the physical properties of the electrolyte and may also deteriorate the physical properties of the positive electrode.

[0025] Furthermore, the plasticizer according to an embodiment may have physical properties that allow it to dissolve lithium salts.

[0026] When a plasticizer and a lithium salt are mixed at a temperature of 60°C or higher at which the plasticizer liquefies, the lithium salt can be solvated and present in the plasticizer. More specifically, when a plasticizer and a lithium salt are mixed at a temperature of 60°C or higher, the plasticizer exists in a liquid state, and the lithium salt dissolves in the plasticizer to form a mixed liquid, and the lithium salt dissolves and exists in a solvated state in the plasticizer.

[0027] Therefore, in the positive electrode according to one embodiment, the lithium salt may be solvated and present in the plasticizer.

[0028] The positive electrode for an all-solid-state battery according to one embodiment includes a lithium salt, and therefore exhibits high ionic conductivity and improved high-rate performance. Conventional positive electrodes for all-solid-state batteries are manufactured using non-polar or low-polarity solvents. Therefore, when a lithium salt with low solubility in the solvent is used in manufacturing the positive electrode, the lithium salt is not solvated, making it difficult to improve ionic conductivity. Furthermore, when a polar solvent capable of dissolving the lithium salt is used in manufacturing the positive electrode, there is a problem that the polar solvent reacts with the solid electrolyte, causing degradation of the solid electrolyte.

[0029] On the other hand, a positive electrode according to one embodiment solves this problem by using a lithium salt together with a plasticizer that is solid at room temperature and liquid at high temperatures, particularly as a polar solvent. Because the plasticizer becomes a polar solvent at high temperatures, the lithium salt dissolves in the plasticizer, i.e., the lithium salt solvates and resides in the plasticizer, improving ionic conductivity. Furthermore, lithium cations formed by dissolving the lithium salt can take on the partial negative charge present in the plasticizer. Even when the plasticizer comes into contact with the electrolyte, there are no sites available for reaction with the electrolyte, so no reaction occurs with the solid electrolyte, eliminating the problem of reaction between the plasticizer and the solid electrolyte.

[0030] In addition, the plasticizer may be liquefied under conditions of elevated temperature, such as during the rolling and drying processes of the positive electrode manufacturing process, and may be sufficiently filled into voids that may be present in the positive electrode layer. As a result, the lithium salt present in the solvated plasticizer may be uniformly and densely present in the positive electrode layer, thereby improving ionic conductivity.

[0031] The plasticizer may be succinonitrile, ethylene carbonate, polycaprolactone, polyethylene glycol (or polyethylene oxide), polytetrahydrofuran (or polytetramethylene ether glycol), or a combination thereof. Such plasticizers do not react with the sulfide-based solid electrolyte, so the solid electrolyte is not decomposed or deteriorated, and there is no problem of deterioration in battery performance due to this.

[0032] The lithium salts include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SOCF)), LiCl, LiBr, LiClO, LiBF, and LiBCl. 10 , LiFP6, LiAsF6, LiSbF6, LiAlCl4, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiF, LiI, LiB(C2O4)2, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyl difluoroborate (LiODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2), LiCF3SO3, or combinations thereof.

[0033] In one embodiment, the content of the plasticizer may be 0.01 wt % to 5 wt %, 0.05 wt % to 5 wt %, 0.1 wt % to 2 wt %, or 0.1 wt % to 1 wt %, based on 100 wt % of the total weight of the positive electrode layer. When the content of the plasticizer is within this range, the ionic conductivity may be further improved while maintaining the physical properties and energy density of the positive electrode.

[0034] The content of the lithium salt may be 0.01 wt % to 5 wt %, 0.05 wt % to 4 wt %, 0.05 wt % to 2 wt %, or 0.1 wt % to 1 wt %, based on 100 wt % of the total weight of the positive electrode layer. When the content of the lithium salt is within this range, the ionic conductivity may be further improved while maintaining the physical properties and energy density of the positive electrode. Furthermore, when the content of the lithium salt is within this range, the balance between the plasticizer and the lithium salt may be better maintained, and the physical properties of the plasticizer, which exists as a solid at room temperature and a liquid at high temperatures, may be better maintained.

[0035] The positive electrode active material may be a positive electrode active material capable of reversibly absorbing and releasing lithium ions. For example, the positive electrode active material may be one or more of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples of the positive electrode active material include Li a A 1-b B 1 b D 1 2(0.90≦a≦1.8, 0≦b≦0.5);Li a E 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 E 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-αF 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 M nb B 1 c D 1 α (0.90≦a≦1.8、0≦b≦05、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 Mr 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 HAVE BEEN 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 bO2(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.

[0036] In the above formula, A is Ni, Co, Mn, or a combination thereof; B 1 is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or combinations thereof, and D 1 is O, F, S, P, or a combination thereof, E is Co, Mn, or a combination thereof, and F 1 is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; and I 1 is Cr, V, Fe, Sc, Y, or a combination thereof, J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof, and L 1 is Mn, Al or a combination thereof.

[0037] According to one embodiment, the positive electrode active material is LiNi x Co y Al z O2(NCA), LiNi x Co y Mn z O2(NCM) (However, 0< x <1, 0< y <1, 0< z <1, x+y+z Examples include ternary lithium transition metal oxides such as .

[0038] Of course, the compound may have a coating layer on its surface, or the compound may be mixed with a compound having a coating layer. The coating layer may include at least one coating element compound selected from the group consisting of oxides of coating elements, hydroxides of coating elements, oxyhydroxides of coating elements, oxycarbonates of coating elements, and hydroxycarbonates of coating elements. The compounds constituting these coating layers may be amorphous or crystalline. The coating elements contained in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer formation process may be performed using any coating method (e.g., spray coating, dipping, etc.) that does not adversely affect the physical properties of the positive electrode active material. Since this method is well understood by those skilled in the art, a detailed description will be omitted.

[0039] In addition, any other coating layer known as a coating layer for a positive electrode active material of an all-solid-state battery can be used, and examples thereof include Li2O-ZrO2 (LZO).

[0040] Here, examples of the shape of the positive electrode active material include particle shapes such as spherical and oval spheres. The average particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to positive electrode active materials of existing all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode active material layer is also not particularly limited, and may be within a range applicable to positive electrode layers of existing all-solid-state secondary batteries.

[0041] In one embodiment, the positive electrode active material may be included in an amount of 55 wt % to 99.7 wt %, for example, 74 wt % to 89.8 wt %, based on the total weight of the positive electrode layer, which may maximize the capacity of the all-solid-state battery while improving its lifespan.

[0042] The sulfide-based solid electrolyte may be a sulfide-based solid electrolyte having excellent ion conductivity. When the solid electrolyte included in the positive electrode according to an embodiment is an oxide-based solid electrolyte rather than a sulfide-based solid electrolyte, a high-temperature sintering process of 700°C or more is performed during the manufacture of the positive electrode. During this process, the plasticizer according to an embodiment may evaporate or decompose, thereby preventing the effects of using the plasticizer from being obtained.

[0043] Examples of the sulfide-based solid electrolyte include 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, and Li2S-P2S5-Z. m S n (m and n are integers of 0 to 12, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are each an integer of 0 to 12, and M is P, Si, Ge, B, Al, Ga, or In), Li a M b P c S d A e (wherein a, b, c, d, and e are each an integer between 0 and 12, inclusive; M is Ge, Sn, Si, or a combination thereof; and A is one of F, Cl, Br, or I). 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-xIx (0≦x≦2). Specifically, Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 etc.

[0044] For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. This mixing ratio range allows for the production of a sulfide-based solid electrolyte with excellent ionic conductivity. Additional components, such as SiS2, GeS2, and B2S3, may be added to further improve ionic conductivity. Mixing methods include mechanical milling, quenching, and solution methods. Additional heat treatment may be performed after mixing. The additional heat treatment may result in a more solid electrolyte crystal.

[0045] 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 to 12, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I), specifically, Li3PS4, Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, etc. Such sulfide-based solid electrolytes have ionic conductivity 10 times that of common liquid electrolytes at room temperature. -4 S / cm~10 -2The high ionic conductivity of the solid electrolyte is close to the S / cm range, and a tight bond can be formed between the positive electrode active material and the solid electrolyte without causing a decrease in ionic conductivity, thereby forming a tight interface between the positive electrode layer and the solid electrolyte layer. All-solid-state batteries including the solid electrolyte can improve battery performance, such as rate capability, coulombic efficiency, and lifespan.

[0046] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof.

[0047] The solid electrolyte may be in the form of particles and may have an average particle size (D50) of 5.0 μm or less, 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. Such a solid electrolyte may effectively penetrate into the positive electrode active material, providing excellent contact with the positive electrode active material and excellent connectivity between the solid electrolyte particles.

[0048] 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 %, based on the total weight of the positive electrode layer. When the solid electrolyte is included in the positive electrode layer in such an amount, the efficiency and life characteristics of the all-solid-state battery can be improved without reducing the capacity.

[0049] The positive electrode layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode and may be any electron-conductive material that does not undergo chemical changes. Examples of the conductive material 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 in the form of metal powder or metal fiber containing copper, nickel, aluminum, silver, and the like; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0050] The conductive material may be included in an amount of 0.1 wt % to 5 wt %, or 0.1 wt % to 3 wt %, based on the total weight of each component of the positive electrode for the all-solid-state battery or the total weight of the positive electrode layer. Within this content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0051] The current collector may comprise, 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 be in foil or sheet form.

[0052] The positive electrode for an all-solid-state battery according to one embodiment can be manufactured by the following steps.

[0053] The plasticizer and the lithium salt are mixed at a temperature of 60° C. or higher at which the plasticizer can be liquefied, for example, at a temperature of 60° C. to 80° C. In the above-mentioned mixing process, the plasticizer is liquefied, so that the lithium salt dissolves in the plasticizer and solvates therein.

[0054] The resulting mixture is mixed with the binder and the solvent at a temperature of 60°C or higher, for example, 60°C to 80°C, and then cooled. The cooling step can be carried out to room temperature, for example, 20°C to 25°C.

[0055] The solvent can be octyl acetate, isobutyl isobutyrate, xylene, or a combination thereof.

[0056] Examples of the binder include, but are not limited to, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, polyacrylonitrile, epoxy resin, nylon, poly(meth)acrylate, polymethyl(meth)acrylate, etc. According to one embodiment, the binder may be at least one selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylonitrile, and polymethyl(meth)acrylate.

[0057] The resulting mixture, a cathode active material, and a solid electrolyte are mixed at room temperature, for example, 20°C to 25°C, to prepare a cathode layer composition. A solvent may be added during the mixing process to adjust viscosity. The solvent may be the same as the solvent used above. A conductive material may also be mixed during this process. The cathode layer composition may also be referred to as a cathode layer-forming composition.

[0058] The positive electrode layer composition is coated on a current collector, dried, and rolled to manufacture a positive electrode. The drying and rolling processes may be performed at a temperature of 80° C. or higher, for example, 80° C. to 130° C. In this case, the plasticizer contained in the positive electrode layer dissolves, and the lithium salt ionically bonded to the plasticizer diffuses and becomes uniformly distributed throughout the positive electrode layer.

[0059] In the manufacturing process, the mixing ratio of the materials used can be appropriately adjusted so that the contents of the plasticizer, lithium salt, positive electrode active material, binder, and conductive material contained in the final positive electrode layer fall within the above-mentioned ranges.

[0060] The all-solid-state battery according to one embodiment includes the positive electrode, the negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The all-solid-state battery may also be referred to as an all-solid-state secondary battery or an all-solid-state lithium secondary battery.

[0061] The negative electrode includes a current collector and a negative electrode layer disposed on one surface of the current collector.

[0062] The negative electrode layer may be a negative electrode active material layer, a negative electrode catalyst layer, or a lithium metal layer.

[0063] The negative electrode active material layer includes a negative electrode active material, and may further include a binder, a conductive material, and / or a solid electrolyte.

[0064] The negative electrode active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, a lithium metal alloy, a material capable of being doped with and dedoped from lithium, or a transition metal oxide.

[0065] The carbon-based negative electrode active material capable of reversibly intercalating / deintercalating lithium ions may include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, thin flake, spherical, or fibrous natural graphite or artificial graphite. Examples of the amorphous carbon include soft carbon, hard carbon, mesophase pitch carbide, and calcined coke.

[0066] The lithium metal alloy may be an alloy of lithium and one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0067] As the substance capable of being doped and undoped with lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. As the Si-based negative electrode active material, silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Si-Q alloy (where Q is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and combinations thereof, and is not Si), as the Sn-based negative electrode active material, Sn, SnO2, a Sn-R alloy (where R is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and combinations thereof, and is not Sn), etc. can be mentioned, and at least one of these can also be used by mixing with SiO2. As the elements Q and R, 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 those selected from the group consisting of combinations thereof can be used.

[0068] The silicon-carbon composite may include, for example, a silicon-carbon composite including a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer disposed on the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. The amorphous carbon precursor may be coal-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, heavy petroleum oil, or a polymer resin such as a phenolic resin, a furan resin, or a polyimide resin. The silicon content may be 10 wt% to 50 wt% based on the total weight of the silicon-carbon composite. The crystalline carbon content may be 10 wt% to 70 wt% based on the total weight of the silicon-carbon composite, and the amorphous carbon content may be 20 wt% to 40 wt% based on the total weight of the silicon-carbon composite. The amorphous carbon coating layer may have a thickness of 5 nm to 100 nm.

[0069] The silicon particles may have an average particle size (D50) of 10 nm to 20 μm, for example, 10 nm to 500 nm. The silicon particles may be present in an oxidized form, and the atomic content ratio of Si:O in the silicon particles, which indicates the degree of oxidation, may be 99:1 to 33:67. The silicon particles may be SiO x particles, where SiO x in x The range can be greater than 0 and less than 2. Here, the average particle size (D50) is measured by a particle size analyzer using a laser diffraction method and means the diameter of particles that make up 50% by volume of the cumulative volume of the particle size distribution.

[0070] The Si-based or Sn-based negative electrode active material may be mixed with a carbon-based negative electrode active material, and the mixing ratio of the Si-based or Sn-based negative electrode active material to the carbon-based negative electrode active material may be 1:99 to 90:10 by weight.

[0071] The content of the negative electrode active material in the negative electrode active material layer may be 95 wt % to 99 wt % based on the total weight of the negative electrode active material layer.

[0072] In one embodiment, the negative electrode active material layer may further include a binder and, optionally, 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. When the conductive material is further included, 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.

[0073] The binder serves to firmly adhere the negative active material particles to each other and to the current collector, and may include a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0074] The water-insoluble binder may include, for example, 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.

[0075] 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, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0076] When a water-soluble binder is used as the negative electrode binder, it may be used together with a thickener that can impart viscosity. The thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, alkali metal salts thereof, or combinations thereof. The alkali metal may be sodium, potassium, or lithium. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the negative electrode active material. The cellulose-based compound may also function as a binder.

[0077] The binder is not limited to these, and any binder used in the art can be used, and the content of these binders can be adjusted as appropriate.

[0078] The conductive material is used to impart conductivity to the electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, and carbon nanotubes; metal-based materials in the form of metal powder or metal fiber, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0079] 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.

[0080] When the anode layer is an anode catalyst layer, the anode refers to a deposition-type anode. A deposition-type anode refers to an anode that does not contain an anode active material when the battery is assembled, but in which lithium metal or the like is deposited during battery charging, serving as the anode active material. More specifically, during charging of an all-solid-state battery, lithium ions are released from the cathode active material, pass through the solid electrolyte, migrate to the anode, and are deposited on the anode current collector, resulting in the formation of a lithium deposition layer between the current collector and the anode layer. Anodes having such a lithium deposition layer are referred to as deposition-type anodes.

[0081] That is, a lithium deposit layer may be formed between the negative electrode current collector and the negative electrode layer.

[0082] The charging step may be a formation step carried out at about 25° C. to 50° C. at 0.05 C to 1 C for 1 to 3 times.

[0083] The thickness of the lithium deposition layer may be 10 μm to 50 μm. For example, the thickness of the lithium deposition layer may be 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more, or 50 μm or less, 40 μm or less, 30 μm or less, or 20 μm or less. When the thickness of the lithium deposition layer is within this range, lithium is reversibly deposited during charge / discharge, which may have the advantage of further improving the lifespan.

[0084] The anode catalyst layer may include a metal, a carbon material, or a combination thereof, which functions as a catalyst. In the anode catalyst layer, for example, a metal may be supported on a carbon material, or a mixture of a metal and a carbon material may be present. In one embodiment, the anode catalyst layer may include a metal and a carbon material.

[0085] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof, and may be amorphous carbon. 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, acetylene black, denka black, ketjen black, furnace black, activated carbon, graphene, or a combination thereof. An example of the carbon black is Super P (Timcal). The amorphous carbon is not limited to this, and any material classified as amorphous carbon in the art may be used.

[0086] The amorphous carbon may be in the form of a single particle, a secondary particle formed by agglomeration of a plurality of primary particles, or a combination thereof.

[0087] The diameter of the single particle may be 10 nm to 60 mm, the diameter of the primary particle may be 20 nm to 100 nm, and the diameter of the secondary particle may be 1 μm to 20 μm.

[0088] In one embodiment, the particle size of the primary particles may be 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, and may be 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less.

[0089] In one embodiment, the particle size of the secondary particles may be 1 μm or more, 3 μm or more, 5 μm or more, 7 μm or more, 10 μm or more, or 15 μm or more, and may be 20 μm or less, 15 μm or less, 10 μm or less, 7 μm or less, 5 μm or less, or 3 μm or less.

[0090] The shape of the primary particles may be spherical, ellipsoidal, plate-like, or a combination thereof, and in one embodiment, the shape of the primary particles may be spherical, ellipsoidal, or a combination thereof.

[0091] The metal particles may be any one selected from Ag, Zn, Al, Sn, Mg, Ge, Cu, In, Ni, Bi, Au, Si, Pt, Pd, and combinations thereof, and in one embodiment, may be Ag. When the negative electrode layer contains the metal particles, the conductivity of the negative electrode can be improved.

[0092] The metal particles may have a size of 5 nm to 800 nm. The size of the metal particles may be 5 nm or more, 50 nm or more, 100 nm or more, 150 nm or more, 200 nm or more, 250 nm or more, 300 nm or more, 350 nm or more, 400 nm or more, 450 nm or more, 500 nm or more, 550 nm or more, 600 nm or more, 650 nm or more, 700 nm or more, or 750 nm or more. The size of the metal particles may be 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 50 nm or less. When the size of the metal particles is within the above range, the battery characteristics (for example, life characteristics) of the all-solid-state battery can be improved.

[0093] When the anode catalyst layer includes a carbonaceous material and metal particles, the weight ratio of the carbonaceous material to the metal particles may be 1:1 to 99:1. For example, the weight of the carbonaceous material relative to the weight of the metal particles may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, 15 or more, 20 or more, 25 or more, 30 or more, 35 or more, 40 or more, 45 or more, 50 or more, 55 or more, 60 or more, 65 or more, 70 or more, 75 or more, 80 or more, 85 or more, 90 or more, or 95 or more, or 99 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, 10 or less, 5 or less, 4 or less, 3 or less, or 2 or less. For example, the weight ratio of the carbon-based material to the metal particles may be 1:1 to 5:1, 1:1 to 10:1, 1:1 to 20:1, 1:1 to 30:1, 1:1 to 40:1, 1:1 to 50:1, 1:1 to 60:1, 1:1 to 70:1, 1:1 to 80:1, or 1:1 to 90:1. When the carbon-based material and the metal particles are contained in the above weight ratio, the conductivity of the negative electrode can be further improved.

[0094] The negative electrode catalyst layer may further include a binder, a conductive material, and / or a solid electrolyte.

[0095] The binder and the conductive material are the same as those described in the negative electrode active material layer.

[0096] The solid electrolyte may be an inorganic solid electrolyte such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte, or a solid polymer electrolyte.

[0097] In one embodiment, the solid electrolyte may be a sulfide-based solid electrolyte having excellent ionic conductivity. Examples of the sulfide-based solid electrolyte include 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, and Li2S-P2S5-Z. m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (wherein p and q are integers, and M is P, Si, Ge, B, Al, Ga, or In).

[0098] For example, the sulfide-based solid electrolyte may be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or in a molar ratio of 50:50 to 80:20. This mixing ratio range allows for the production of a sulfide-based solid electrolyte with excellent ionic conductivity. Additional components, such as SiS2, GeS2, and B2S3, may be added to further improve ionic conductivity. Mixing methods may include mechanical milling, quenching, or solution processing. Additional heat treatment may be performed after mixing. The additional heat treatment may further harden the crystals of the solid electrolyte.

[0099] 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 to 12, M is Ge, Sn, Si, or a combination thereof, and A is one of F, Cl, Br, or I), specifically, Li3PS4, Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, etc. Such sulfide-based solid electrolytes have the ionic conductivity of a general liquid electrolyte at room temperature. -4 S / cm~10 -2 The solid electrolyte has high ionic conductivity close to the 500 S / cm range, and can form a tight bond between the active material and the solid electrolyte without causing a decrease in ionic conductivity, thereby forming a tight interface between the anode layer and the solid electrolyte layer. All-solid-state batteries including this can improve battery performance such as rate capability, coulombic efficiency, and lifespan.

[0100] The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof.

[0101] The solid electrolyte may be an oxide-based inorganic solid electrolyte other than a sulfide-based material. The oxide-based inorganic solid electrolyte may 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), Li1 +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 - GeO2 - based ceramics, Garnet - based ceramics Li 3+x La3M2O 12 (M = Te, Nb, or Zr; x is an integer from 1 to 10), or mixtures thereof can be included.

[0102] The solid electrolyte is in particle form, and the average particle size (D50) can be 5.0 μm or less, 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. Such a solid electrolyte can effectively penetrate between the positive electrode active materials and has excellent contact with the positive electrode active materials and connectivity between the solid electrolyte particles.

[0103] The negative electrode catalyst layer can further contain additives such as fillers, dispersants, and ion - conductive materials, for example. Also, known materials generally used in all - solid - state batteries can be used as fillers, dispersants, ion - conductive materials, etc. that can be included in the negative electrode catalyst layer.

[0104] The thickness of the negative electrode catalyst layer can be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0105] For example, the deposition-type negative electrode may further include a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode catalyst 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 or a combination of these elements. The thin film may further flatten the deposition morphology of the lithium metal layer, thereby further improving the characteristics of the all-solid-state 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.

[0106] The current collector in the deposition-type negative electrode 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 be in the form of a foil or sheet.

[0107] The solid electrolyte included in the solid electrolyte layer may be a sulfide-based solid electrolyte, for example, an argyrodite-type sulfide-based solid electrolyte. Such a sulfide-based solid electrolyte has superior ionic conductivity compared to other solid electrolytes, such as oxide-based solid electrolytes, and is suitable for use in a battery, and can exhibit excellent life characteristics over a wider operating range.

[0108] In one embodiment, the solid electrolyte is Li a M b P c S d A e (wherein a, b, c, d, and e are each an integer of 0 to 12, inclusive; M is Ge, Sn, Si, or a combination thereof; and A is one of F, Cl, Br, or I), specifically, Li3PS4, Li7P3S 11 , Li6PS5Cl, Li6PS5Br, Li6PS5I, etc.

[0109] The solid electrolyte may be in an amorphous state, a crystalline state, or a mixture thereof.

[0110] Of course, a commercially available sulfide-based solid electrolyte can also be used.

[0111] The solid electrolyte layer may further include a binder. The binder may be, but is not limited to, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate-based polymer, or a combination thereof. Any binder commonly used in the art may be used. The acrylate-based polymer may be butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0112] The solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the resulting solution on a substrate film, and drying. The solvent for the binder solution can be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. The process for forming the solid electrolyte layer is widely known in the art, and therefore, a detailed description thereof will be omitted herein.

[0113] In one embodiment, a buffer material may be further included to buffer thickness changes that occur during charge and discharge of the all-solid-state battery. The buffer material may be located between the negative electrode and the case, and in the case of a battery in which one or more electrode assemblies are stacked, the buffer material may be located between different electrode assemblies.

[0114] The buffer material may be a material having an elastic recovery rate of 50% or more and having an insulating function, such as silicone rubber, acrylic rubber, fluorine-based rubber, nylon, synthetic rubber, or a combination thereof. The buffer material may be in the form of a polymer sheet.

[0115] An all-solid-state battery according to an embodiment may be manufactured by preparing a stack of an anode, a cathode, and a solid electrolyte layer disposed between the anode and the cathode, and pressing the stack.

[0116] The pressurizing step may be carried out at a temperature in the range of 25°C to 90°C. The pressurizing step may be carried out at a pressure of 550 MPa or less, for example, 500 MPa or less, for example, in the range of 5 MPa to 500 MPa. The pressurizing time may vary depending on the temperature and pressure, and may be, for example, less than 30 minutes. The pressurizing step may be any step that can apply pressure to the laminate.

[0117] FIG. 1 is a cross-sectional view of an all-solid-state battery according to an embodiment. Referring to FIG. 1, the all-solid-state battery 100 may have a structure in which an electrode assembly including a stack of an anode 400 including an anode current collector 401 and an anode active material layer 403, a solid electrolyte layer 300, and a cathode 200 including a cathode active material layer 203 and a cathode current collector 201 is housed in a case such as a pouch. The all-solid-state battery 100 may further include an elastic layer 500 on the outer surface of at least one of the cathode 200 and the anode 400. Although FIG. 1 shows one electrode assembly including the anode 400, the solid electrolyte layer 300, and the cathode 200, two or more electrode assemblies may be stacked to fabricate an all-solid-state battery.

[0118] 2 is a schematic diagram showing the structure of an all-solid-state battery including a deposition-type anode according to another embodiment. The all-solid-state battery 100 includes a cathode 200 including a cathode current collector 201 and a cathode active material layer 203, an anode current collector 401, a deposition-type anode 400′ including an anode catalyst layer 403, and a solid electrolyte 300 located between the cathode 200 and the deposition-type anode 400′, and a battery case 500 that houses these components.

[0119] In such an all-solid-state battery, during charging, lithium ions are released from the positive electrode active material and deposited on the negative electrode current collector 401′, resulting in the formation of a lithium deposition layer 405′ between the current collector 401′ and the deposition-type negative electrode 403′.

[0120] [Mode for Carrying Out the Invention] Examples of the present invention and comparative examples are described below. These examples are merely illustrative of the present invention, and the present invention is not limited to these examples.

[0121] Example 1 (1) Manufacturing of the positive electrode Succinonitrile plasticizer and LiN(SO2CF3)2 lithium salt were mixed at 60°C. The resulting mixture was mixed with polyvinylidene fluoride binder and octyl acetate solvent at a temperature of 60°C and cooled to 20°C.

[0122] The resulting product, LiNi 0.8 Co 0.1 Al 0.1 A cathode layer slurry was prepared by mixing O2 cathode active material, azirodite-type solid electrolyte Li6PS5Cl, and carbon nanotube conductive material in an octyl acetate solvent, with the final cathode having a weight ratio of 84.46:13.42:0.35:1.13:0.4:0.24 (cathode active material, solid electrolyte, conductive material, plasticizer, and lithium salt).

[0123] The cathode layer slurry was coated on an aluminum foil current collector, and then dried and rolled at 60° C. to prepare a cathode for an all-solid-state battery. In the prepared cathode, the succinonitrile was present in a liquid state, and the lithium salt was dissolved in the succinonitrile and present in a solvated state. The plasticizer content was 0.4 wt % relative to 100 wt % of the total cathode layer, and the lithium salt content was 0.24 wt % relative to 100 wt % of the total cathode layer.

[0124] (2) Manufacturing of the negative electrode Polyvinylidene fluoride binder, Ag nanoparticles (D50: 60 nm), and carbon black were mixed. The carbon black was a mixture of single particles with a particle size of 38 nm and secondary particles, and the secondary particles were 275 nm in diameter, consisting of aggregates of primary particles with a particle size of 76 nm. The mixing ratio of the binder, Ag nanoparticles, and carbon black was 11:40:120 by weight.

[0125] The mixture was stirred in a Sinky mixer to adjust the viscosity to an appropriate level. After adjusting the viscosity, 2 mm zirconia balls were added and the mixture was stirred again in a Sinky mixer to prepare a slurry. The stirred slurry was coated on a stainless steel foil current collector and then vacuum dried at 100°C to prepare a negative electrode including a 5 μm-thick negative electrode catalyst layer and a 10 μm-thick current collector. The binder content in the negative electrode catalyst layer was 9 wt % relative to 100 wt % of the total negative electrode active material, and the thickness of the negative electrode catalyst layer was 5 μm.

[0126] (3) Manufacturing of solid electrolyte layer The ajirodite-type solid electrolyte Li6PS5Cl was mixed with an isobutylyl isobutylate binder solution (solid content: 50 wt%) containing butyl acrylate, an acrylate polymer. The mixing ratio of the solid electrolyte to the binder was 98.7:1.3 by weight.

[0127] The mixing process was carried out using a Thinky mixer. 2 mm zirconia balls were added to the resulting mixture, and the mixture was stirred again using the Thinky mixer to prepare a slurry. The slurry was cast onto a peelable polytetrafluoroethylene film and dried at room temperature to prepare a solid electrolyte with a thickness of 5 μm.

[0128] (4) Manufacturing of all-solid-state batteries The prepared negative electrode, solid electrolyte, and positive electrode were sequentially stacked and a pressure of 10 MPa was applied to prepare an all-solid-state battery. In the prepared battery, the thickness of the positive electrode layer (excluding the current collector) was 100 μm, the thickness of the negative electrode catalyst layer (excluding the current collector) was 7 μm, and the thickness of the solid electrolyte layer was 60 μm.

[0129] (Examples 2 to 4 and Comparative Examples 1 to 3) The resulting product, LiNi, was mixed so that the weight ratio of the positive electrode active material, solid electrolyte, conductive material, plasticizer, and lithium salt in the final positive electrode was as shown in Table 1 below. 0.8 Co 0.1 Al 0.1 The cathode was prepared in the same manner as in Example 1, except that the O2 cathode active material, the azirodite-type solid electrolyte Li6PS5Cl, and the carbon nanotube conductive material were mixed in an octyl acetate solvent. The plasticizer content and lithium salt content of the prepared cathode are shown in Table 1 below.

[0130] An all-solid-state battery was manufactured in the same manner as in Example 1, except that the prepared positive electrode was used.

[0131] [Table 1]

[0132] Experimental Example 1) Evaluation of ionic and electronic conductivity The positive electrodes prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were punched into 10 mm circles, and a torque of 10 N·m was applied to prepare samples.

[0133] The ionic and electronic conductivities of the prepared samples were determined using the resistance measured by electrochemical impedance spectroscopy (EIS). The EIS measurement was performed at an amplitude of 50 mV, a frequency of 500 kHz to 50 mHz, and a temperature of 45°C.

[0134] [Table 2]

[0135] As shown in Table 2, the all-solid-state batteries of Examples 1 and 2 exhibited similar electronic conductivity values ​​to those of Comparative Examples 1 to 3, but also exhibited excellent ionic conductivity values.

[0136] Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it is of course understood that these modifications also fall within the scope of the present invention.

Claims

1. A positive electrode layer including a positive electrode active material, a sulfide-based solid electrolyte, a plasticizer that is solid at room temperature and liquid at 60°C or higher, and a lithium salt; a current collector supporting the positive electrode layer; A cathode for an all-solid-state battery, comprising:

2. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the lithium salt is ionized and present in the plasticizer.

3. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the plasticizer is succinonitrile, ethylene carbonate, cyclic phosphate, polycaprolactone, polyethylene glycol (or polyethylene oxide), polytetrahydrofuran (or polytetramethylene ether glycol), or a combination thereof.

4. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the content of the plasticizer is 0.05% by weight to 5% by weight with respect to 100% by weight of the entire positive electrode layer.

5. The lithium salt is lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO 2 CF 3 ) 2 ), LiCl, LiBr, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiFP 6 , LiAsF 6 , LiSbF 6 , LiAlCl ４ , LiSCN, LiN(CN) 2 , Li(CF 3 SO 2 ) 3 C, LiC 4 F 9 SO 3 , LiN(SO 2 CF 2 CF 3 ) 2 , LiF, LiI, LiB(C 2 O 4 ) 2 , LiBF 3 (C 2 F 5 ), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO 2 F) 2 ), LiCF 3 SO 3 10. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode is a SiO 2 -SiO 3 ...

6. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the content of the lithium salt is 0.01% by weight to 5% by weight with respect to 100% by weight of the entire positive electrode layer.

7. 2. The positive electrode for an all-solid-state battery according to claim 1, wherein the sulfide-based solid electrolyte is an ajirodite-type sulfide-based solid electrolyte.

8. The positive electrode according to any one of claims 1 to 7, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode; Including solid-state batteries.

9. The all-solid-state battery according to claim 8 , wherein the negative electrode includes a current collector and a negative electrode active material layer or a negative electrode catalyst layer located on the current collector.

10. 9. The all-solid-state battery according to claim 8, wherein the negative electrode comprises a current collector and a lithium metal layer located on the current collector.

11. The all-solid-state battery according to claim 9 , wherein the anode catalyst layer contains amorphous carbon and a metal.

12. 10. The all-solid-state battery according to claim 9, wherein the negative electrode includes a current collector and a negative electrode catalyst layer located on the current collector, and further includes a lithium deposition layer formed during initial charging between the current collector and the negative electrode catalyst layer.

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