Sulfide-based solid electrolyte, method for preparing same, and all-solid-state battery comprising same

Abstract

The present invention relates to a method for preparing a sulfide-based solid electrolyte, the method comprising the steps of: preparing, as raw materials, a lithium compound, a phosphorus compound, and a halogen compound; adding a sintering agent containing boron to the raw materials and dry-mixing same to form a mixture; adding the mixture to a pelletizer to prepare pellets; and firing the pellets in an inert atmosphere, wherein the pelletizer has a pattern depth of 0.2-1.8 mm.

Description

Sulfide-based solid electrolyte, method for manufacturing the same, and all-solid-state battery including the same

[0001] The present invention relates to a sulfide-based solid electrolyte, a method for manufacturing the same, and an all-solid-state battery containing the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0191967 filed on December 19, 2024, the entire contents of said prior application are incorporated herein by reference.

[0003] With the recent increase in demand for electric vehicles, the demand for high-energy, high-output lithium-ion batteries is also rising. Lithium-ion batteries have the advantage of higher energy density and greater capacity per unit area compared to nickel-manganese or nickel-cadmium batteries.

[0004] However, conventional lithium-ion batteries mainly used flammable organic liquid electrolytes as electrolytes, which caused safety issues such as overheating. Recently, all-solid-state batteries using non-flammable solid electrolytes have been gaining attention.

[0005] All-solid-state batteries are batteries that ensure safety by replacing the liquid electrolyte, which causes explosions, with a solid electrolyte and eliminating the use of flammable solvents within the battery, thereby preventing any ignition or explosion caused by the decomposition reaction of conventional electrolytes.

[0006] Inorganic solid electrolytes are generally used in all-solid-state batteries. Among solid electrolytes, sulfides are characterized by high ionic conductivity and relative flexibility, making it easy to form solid-solid interfaces. Additionally, they are stable with respect to active materials, leading to various ongoing studies on sulfide-based solid electrolytes.

[0007] However, sulfide-based solid electrolytes are expensive, and there is a problem that production costs may increase when manufactured using a wet mixing process to improve production volume. Therefore, there is a need to develop a method for manufacturing sulfide-based solid electrolytes that can lower process costs and improve the quality of the solid electrolyte.

[0008] One objective of the present invention is to provide a high-quality sulfide-based solid electrolyte.

[0009] Another objective of the present invention is to provide a method for manufacturing a sulfide-based solid electrolyte that reduces process costs by mixing raw materials and sintering materials using a pelletizer and synthesizing the solid electrolyte through a simple mixing process.

[0010] A method for manufacturing a sulfide-based solid electrolyte according to one embodiment of the present invention comprises: a step of preparing a raw material by mixing a lithium compound, a phosphorus compound, and a halogen compound; a step of forming a mixture by introducing a sintering material containing boron into the raw material; a step of manufacturing a pellet by introducing the mixture into a pelletizer comprising a plurality of cylindrical rollers; and a step of firing the pellet in an inert atmosphere; wherein the surface of the plurality of rollers includes a pattern, and the depth of the pattern is 0.2 to 1.8 mm.

[0011] The rotational speed of the plurality of cylindrical rollers mentioned above may be 1 to 15 rpm.

[0012] The diameter of the above pattern may be 1 to 5 mm.

[0013] The gap between the plurality of rollers may be 10 to 30 μm.

[0014] The step of forming the above mixture; and the step of manufacturing the above pellets; may be repeated 1 to 10 times.

[0015] The above pelletizer may produce pellets by applying a pressure of 100 to 500 MPa.

[0016] The firing temperature of the above firing step may be 300 to 700℃.

[0017] The above inert atmosphere may include at least one inert gas selected from argon, hydrogen, nitrogen, helium, neon, xenon, and krypton.

[0018] The above lithium compound may be lithium sulfide (Li2S) and the above phosphorus compound may be phosphorus pentasulfide (P2S5).

[0019] The amount of lithium sulfide (Li2S) added may be 30 to 50 weight percent based on the total mixture, and the amount of phosphorus pentasulfide (P2S5) added may be 40 to 50 weight percent based on the total mixture.

[0020] The above halogen compound may include at least one halogen compound selected from lithium bromide (LiBr), lithium chloride (LiCl), lithium fluoride (LiF), and lithium iodide (LiI).

[0021] The amount of the above halogen compound added may be 10 to 30 weight percent based on the total mixture.

[0022] The above sintered material may include at least one of B2O3, H3BO3, Li3BO3, BBr3, and BCl3.

[0023] The amount of the above-mentioned sintered material added may be 1 to 5 weight percent based on the total mixture.

[0024] In a sulfide-based solid electrolyte according to another embodiment of the present invention, the sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), sulfur (S), and halogen elements comprises 1 to 5 weight% of B2O3 sintered material, and the ionic conductivity of the sulfide-based solid electrolyte is 2.2 to 4 mS / cm.

[0025] The molar ratio of lithium (Li) to phosphorus ([P]) ([Li] / [P]) may be 5.5 to 7.0.

[0026] The molar ratio of sulfur (S) to phosphorus ([P]) ([S] / [P]) may be 4.5 to 5.5.

[0027] The molar ratio of halogen (D) to phosphorus ([P]) ([D] / [P]) may be 0.5 to 1.5.

[0028] A solid-state battery according to another embodiment of the present invention comprises: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein the solid electrolyte layer comprises the aforementioned sulfide-based solid electrolyte.

[0029] According to one embodiment of the present invention, a sulfide-based solid electrolyte can be manufactured at a low cost and with excellent quality by combining a simple mixing process with a pelletizer, by introducing raw materials and sintering materials at once. In addition, the cost of solvent treatment can be reduced by performing particle size classification with a cyclone, and the production unit cost can be lowered by continuously producing solid electrolytes.

[0030] FIG. 1 is a schematic diagram showing a method for manufacturing a sulfide-based solid electrolyte according to one embodiment of the present invention.

[0031] FIG. 2 is an image of a plurality of cylindrical rollers including a pattern within a pelletizer used in the manufacture of a sulfide-based solid electrolyte according to one embodiment of the present invention.

[0032] In this specification, terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the invention.

[0033] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0034] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0035] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0036] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0037] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0038] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0039] Method for manufacturing sulfide-based solid electrolytes

[0040] A method for manufacturing a sulfide-based solid electrolyte according to an embodiment of the present invention comprises: a step of preparing a raw material by mixing a lithium compound, a phosphorus compound, and a halogen compound; a step of forming a mixture by introducing a sintering material containing boron into the raw material; a step of manufacturing a pellet by introducing the mixture into a pelletizer comprising a plurality of cylindrical rollers; and a step of firing the pellet in an inert atmosphere; wherein the surface of the plurality of rollers includes a pattern, and the depth of the pattern is 0.2 to 1.8 mm. Specifically, the depth of the pattern of the pelletizer may be 0.5 to 1.5 mm. If the depth of the pattern satisfies the above range, the flow of the raw material is optimized, thereby increasing processing efficiency and improving productivity. On the other hand, if the depth of the pattern is too shallow, the pellet size may become uneven, leading to a problem of quality degradation. Additionally, if the depth of the pattern is too deep, the structural strength of the pellet may be weakened.

[0041] Referring to Figure 1, a schematic method for manufacturing a sulfide-based solid electrolyte can be confirmed.

[0042] Referring to FIG. 2, the shape of a pelletizer including a plurality of cylindrical rollers can be seen, and a pattern of a certain shape is formed on the surface of the plurality of rollers.

[0043] In one embodiment, the rotational speed of the plurality of cylindrical rollers may be 1 to 15 rpm, specifically 3 to 10 rpm. When the rotational speed satisfies the above range, pellets of uniform size are manufactured, and the quality of the solid electrolyte can be improved. On the other hand, if the rotational speed is too slow, sufficient mixing between the raw material and the sintering material is not achieved, resulting in particle non-uniformity and potentially degrading the quality of the solid electrolyte. Additionally, if the rotational speed is too fast, collisions between particles increase, leading to particle breakage or excessive heat generation, which may cause problems such as increased mechanical load.

[0044] In one embodiment, the diameter of the pattern may be 1 to 5 mm, specifically 2 to 4 mm. If the diameter of the pattern satisfies the above range, the particle size is relatively uniform, which may provide the advantage of facilitating processing in subsequent processes. On the other hand, if the diameter of the pattern is too small, the contact area between particles may decrease or become non-uniform, which may cause a problem of reduced ionic conductivity of the solid electrolyte. In addition, if the diameter of the pattern is too large, it may be difficult to obtain a uniform density during the sintering process.

[0045] In one embodiment, the gap between the plurality of rollers may be 10 to 30 μm, specifically 15 to 25 μm. If the gap satisfies the above range, the density of the pellets can be increased to improve the ionic conductivity of the solid electrolyte. On the other hand, if the gap is too narrow, the pellets may be damaged due to excessive pressure or excessive heat may be generated, which may reduce the chemical stability of the solid electrolyte. In addition, if the gap is too wide, the compression of the pellets is insufficient, which weakens the bonding force between particles and may reduce the mechanical strength and ionic conductivity of the solid electrolyte.

[0046] In one embodiment, the step of forming the mixture; and the step of manufacturing the pellet; may be repeated 1 to 10 times, specifically 1 to 5 times. If the number of repetitions satisfies the above range, pellets with uniform particle size can be manufactured.

[0047] In one embodiment, the pelletizer can produce pellets by applying a pressure of 100 to 500 MPa, specifically 250 to 450 MPa. When the pressure of the pelletizer satisfies the above range, the pellets can be uniformly compressed to form high-density pellets, thereby increasing the bonding strength between particles. On the other hand, if the pressure of the pelletizer is too weak, the density of the pellets decreases, which may cause the pellets to break easily. In addition, if the pressure of the pelletizer is too high, it may place an excessive load on the pelletizer equipment, leading to mechanical damage.

[0048] In one embodiment, the calcination temperature of the calcination step may be 300 to 700°C, specifically 350 to 650°C, and more specifically 400 to 600°C. If the calcination temperature satisfies the above range, the structural stability of the sulfide-based solid electrolyte may be improved. On the other hand, if the calcination temperature is too low, a problem may occur in which the ionic conductivity decreases due to incomplete crystallization during the manufacture of the sulfide-based solid electrolyte. In addition, if the heat treatment temperature is too high, a problem may occur in which the structure becomes unstable or other crystal phases are formed.

[0049] In one embodiment, the inert atmosphere may include at least one inert gas selected from argon, hydrogen, nitrogen, helium, neon, xenon, and krypton.

[0050] In one embodiment, the lithium compound may be lithium sulfide (Li2S) and the phosphorus compound may be phosphorus pentasulfide (P2S5).

[0051] Specifically, the amount of lithium sulfide (Li2S) added may be 30 to 50 weight percent based on the total mixture, specifically 37 to 48 weight percent, and more specifically 35 to 45 weight percent. If the amount of lithium sulfide (Li2S) added satisfies the above range, the ionic conductivity of the sulfide-based solid electrolyte is improved, thereby maximizing the performance of the battery. On the other hand, if the amount of lithium sulfide (Li2S) added is too small, the ionic conductivity of the solid electrolyte decreases, which may lead to a problem where the output and efficiency of the battery are reduced. Furthermore, if the amount of lithium sulfide added is too large, it may obstruct the ion conduction pathway, thereby reducing the ionic conductivity of the sulfide-based solid electrolyte.

[0052] The amount of phosphorus pentasulfide (P2S5) added may be 40 to 50 weight percent based on the total mixture, specifically 42 to 48 weight percent, and more specifically 44 to 46 weight percent. If the amount of phosphorus pentasulfide (P2S5) added satisfies the above range, the chemical stability of the solid electrolyte is improved, and the cycle stability of the battery can be improved. On the other hand, if the amount of phosphorus pentasulfide (P2S5) added is too small, the ionic conductivity is reduced, which may cause a problem of reduced efficiency of the battery. In addition, if the amount of phosphorus pentasulfide (P2S5) added is too large, it may lead to structural instability of the solid electrolyte.

[0053] In one embodiment, the halogen compound may include at least one of lithium bromide (LiBr), lithium chloride (LiCl), lithium fluoride (LiF), and lithium iodide (LiI), but is not limited thereto, and any material capable of improving the moisture stability and ion conductivity of the sulfide-based solid electrolyte may be used.

[0054] In one embodiment, the amount of the halogen compound added may be 10 to 30 weight percent based on the total mixture, specifically 12 to 28 weight percent, and more specifically 15 to 25 weight percent. When the amount of the halogen compound satisfies the above range, the crystal structure of the solid electrolyte may be improved, the ion transport pathway may be made more efficient, interfacial resistance may be reduced, and electrochemical stability may be improved. On the other hand, if the amount added is too small, the improvement in the ion conductivity of the solid electrolyte may not be sufficient. In addition, if the amount added is too large, structural instability of the solid electrolyte may occur, and problems such as deterioration of the mechanical properties of the electrolyte may arise.

[0055] In one embodiment, the sintering material may include at least one of B2O3, H3BO3, Li3BO3, BBr3, and BCl3, but is not limited thereto, and any material capable of being sintered at a low sintering temperature during sintering of a sulfide-based solid electrolyte may be used.

[0056] In one embodiment, the amount of the sintering material added may be 1 to 5 weight percent based on the total mixture, specifically 2 to 4 weight percent. When the amount of the sintering material added satisfies the above range, the interparticle bonding force is strengthened, which can improve the ion conductivity of the solid electrolyte. On the other hand, if the amount of the sintering material added is too small, it is difficult to maintain the uniformity of the microstructure, and the performance of the solid electrolyte may be degraded. In addition, if the amount of the sintering material added is too excessive, a problem may occur in which the ion movement path within the solid electrolyte is obstructed, thereby reducing ion conductivity.

[0057]

[0058] Sulfide-based solid electrolytes

[0059] In a sulfide-based solid electrolyte according to another embodiment of the present invention, the sulfide-based solid electrolyte comprising lithium (Li), phosphorus (P), sulfur (S), and halogen elements comprises 1 to 5 weight% of B2O3 sintered material, and the ionic conductivity of the sulfide-based solid electrolyte may be 2.2 to 4 mS / cm, specifically 2.4 to 3.5 mS / cm. When the ionic conductivity satisfies the above range, the interfacial resistance between the solid electrolyte and the electrode is reduced, thereby increasing thermal and chemical stability during the manufacture of an all-solid-state battery. On the other hand, if the ionic conductivity is too low, electrical resistance increases, which may lead to problems such as reduced efficiency and increased heat generation. Furthermore, if the ionic conductivity is too high, the structural stability of the solid electrolyte is reduced, which may promote side reactions between the solid electrolyte and the electrode.

[0060] In another embodiment, the molar ratio of lithium (Li) to phosphorus ([P]) ([Li] / [P]) may be 5.5 to 7.0, specifically 5.8 to 6.5. When the molar ratio of lithium (Li) to phosphorus (P) satisfies the above range, the ionic conductivity of the sulfide-based solid electrolyte is improved, which may have the advantage of improving electrochemical stability and increasing charge / discharge efficiency when manufacturing an all-solid-state battery. On the other hand, if the molar ratio of lithium (Li) to phosphorus (P) is too low, problems may arise such as a decrease in the ionic conductivity of the sulfide-based solid electrolyte and a reduction in the mobility of lithium ions. Furthermore, if the molar ratio of lithium (Li) to phosphorus (P) is too high, problems may arise such as reduced safety due to structural instability caused by excessive lithium and an increased possibility of electrolyte decomposition.

[0061] In another embodiment, the molar ratio of sulfur (S) to phosphorus ([P]) ([S] / [P]) may be 4.5 to 5.5, specifically 4.8 to 5.2. When the molar ratio of sulfur (S) to phosphorus (P) satisfies the above range, a stable crystal structure is formed, which may have the advantage of improving the stability of the sulfide-based solid electrolyte. On the other hand, if the molar ratio of sulfur (S) to phosphorus (P) is too low, the ionic conductivity of the sulfide-based solid electrolyte may decrease and problems with an unstable crystal structure may occur. In addition, if the molar ratio of sulfur (S) to phosphorus (P) is too high, problems may occur in which the characteristics of the sulfide-based solid electrolyte and the performance of the all-solid-state battery decrease due to excessive sulfur content.

[0062] In another embodiment, the molar ratio ([D] / [P]) of the halogen (D) to the phosphorus ([P]) may be 0.5 to 1.5, specifically 0.8 to 1.2. When the molar ratio of the halogen element (D) to the phosphorus (P) satisfies the above range, the thermal stability of the solid electrolyte is improved and the interfacial resistance is reduced, thereby improving the performance of the all-solid-state battery. On the other hand, if the molar ratio of the halogen element (D) to the phosphorus (P) is too low, the distribution of the halogen element within the sulfide-based solid electrolyte becomes uneven due to insufficient halogen doping, which may result in local performance differences. Additionally, if the molar ratio of the halogen element (D) to the phosphorus (P) is too high, the halogen element may be excessively doped, which may lower the structural stability of the solid electrolyte and cause a decrease in battery performance due to side reactions with the electrode material.

[0063] All-solid-state battery

[0064] A solid-state battery according to another embodiment of the present invention comprises: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein the solid electrolyte layer comprises the aforementioned sulfide-based solid electrolyte.

[0065] (Bipolar layer)

[0066] More specifically, the anode layer may include an anode current collector and an anode active material layer disposed on the anode current collector.

[0067] The above-mentioned positive active material layer may further include, for example, a positive active material and, optionally, a solid electrolyte. The solid electrolyte included in the positive active material layer may be the same as or different from the solid electrolyte according to one embodiment of the present invention, and may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0068] The cathode active material is a material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may be, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these; any material used as a cathode active material in the relevant technical field is acceptable. The cathode active material may be a single material or a mixture of two or more materials.

[0069] The above lithium transition metal oxide is, for example, Li a A 1-b B b D2(wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B b O4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Co b B c O 2-α F2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B c O 2-α F α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B c O 2-α F2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G dO2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d GeO2(wherein the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(in the above equation, 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f)Fe2(PO4)3(0 ≤ f ≤ 2); a compound represented by any one of the chemical formulas of LiFePO4. In such a compound, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F 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; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. A compound having a coating layer added to the surface of such a compound may also be used, and a mixture of the compound described above and a compound having a coating layer added may also be used. The coating layer applied to the surface of such compounds comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0070] The positive active material layer may include, for example, a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable.

[0071] The positive active material layer may include, for example, a conductive material. The conductive material may include, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc., but is not limited to these, and any material used as a conductive material in the relevant technical field is acceptable.

[0072] The positive active material layer may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, binder, and conductive material described above, for example.

[0073] As fillers, coating agents, dispersants, ion conductivity aids, etc. that may be included in the positive electrode active material layer, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0074] The positive current collector may be a plate or foil made of, 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 alloys thereof. The thickness of the positive current collector may be, for example, 1 µm to 100 µm, 1 µm to 50 µm, 5 µm to 25 µm, or 10 µm to 20 µm.

[0075] (Cathode layer)

[0076] More specifically, the above cathode layer may include a cathode current collector and a cathode active material layer disposed on the cathode current collector.

[0077] The above-mentioned cathode active material layer may include, for example, a cathode active material and a binder, and may optionally further include a solid electrolyte as needed.

[0078] The above-mentioned negative electrode active material may include, for example, a carbon-based negative electrode active material, a metal / metallic negative electrode active material, or a combination thereof.

[0079] The carbon-based cathode active material may be amorphous carbon, crystalline carbon, or a mixture or composite thereof. The amorphous carbon may be, for example, carbon black (CB), acetylene black (AB), furnace black (FB), Kettjen black (KB), graphene, etc., but is not necessarily limited to these, and any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon. The crystalline carbon may be, for example, natural graphite, artificial graphite, or a combination thereof.

[0080] The metal / metallic anode active material comprises one or more selected from the group consisting of lithium (Li), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited to these, and any metal anode active material or metallic anode active material that forms an alloy or compound with lithium in the relevant technical field is acceptable.

[0081] The binder included in the negative electrode active material layer may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any binder used in the relevant technical field is acceptable. The binder may be composed of a single binder or a plurality of different binders.

[0082] The cathode active material layer is stabilized on the cathode current collector by including a binder. In addition, cracking of the cathode active material layer is suppressed despite volume changes and / or relative positional changes of the cathode active material layer during the charging and discharging process.

[0083] The negative electrode active material layer may further include additives used in conventional all-solid-state batteries, such as fillers, coating agents, dispersants, ion conductivity aids, etc.

[0084] The all-solid-state battery may further include a second negative electrode active material layer disposed between the negative electrode current collector and the negative electrode active material layer upon charging. The second negative electrode active material layer may be deposited between the negative electrode current collector and the negative electrode current collector during the charging process, or may be further disposed on the negative electrode active material layer during electrode assembly. This second negative electrode active material layer may be a metal layer comprising lithium 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, a Li-Si alloy, but is not limited thereto; any alloy used as a lithium alloy in the relevant technical field is acceptable. The second negative electrode active material layer may be composed of one of these alloys and / or lithium, or may be composed of various types of alloys and / or lithium.

[0085] The negative electrode current collector may be composed of, for example, a material that does not react with lithium, that is, does not form either an alloy or a compound. The negative electrode current collector may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector may be, for example, in the form of a plate or a foil.

[0086] When the above-mentioned cathode active material layer includes a solid electrolyte, the solid electrolyte included in the above-mentioned cathode active material layer may be the same as or different from the solid electrolyte according to one embodiment of the present invention, and may be the same as or different from the solid electrolyte included in the solid electrolyte layer.

[0087] (Solid electrolyte layer)

[0088] The above solid electrolyte layer can be manufactured by mixing and drying the aforementioned solid electrolyte and binder, or by rolling the aforementioned solid electrolyte powder into a certain shape under a pressure of 1 ton to 10 ton.

[0089] At this time, the solid electrolyte may be in the form of a powder or a molded article. The solid electrolyte in the form of a molded article may be, for example, in the form of pellets, sheets, thin films, etc., but is not necessarily limited to these and may have various forms depending on the application.

[0090] The above solid electrolyte layer may, if necessary, further include a solid electrolyte such as a conventional sulfide-based solid electrolyte and / or an oxide-based solid electrolyte in addition to the aforementioned solid electrolyte.

[0091] The above binder is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyvinyl alcohol, etc., but is not limited to these, and any binder used in the relevant technical field is acceptable. The binder of the solid electrolyte layer may be of the same type as or different from the binders of the anode layer and the cathode layer.

[0092] Another embodiment of the present invention provides an electric vehicle comprising the all-solid-state battery.

[0093] The embodiments of the present invention will be described in more detail below through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited by the following examples.

[0094] Example 1

[0095] 1-1. Method for manufacturing sulfide-based solid electrolytes

[0096] A mixture was prepared by adding 3.0 wt% of B2O3 as a sintering agent to raw materials that had been quantified and mixed with a mixer, including Li2S, P2S5, LiCl, and Li3PO4. The mixture was then pressed at a rotational speed of 3 rpm and 300 MPa using a pelletizer comprising a plurality of cylindrical rollers with a pattern diameter of 3 mm, a pattern depth of 1.5 mm, and a gap between rollers of 25 μm to form pellets, and the process of mixing with a mixer was repeated once, followed by heat treatment at 500°C in an Ar atmosphere.

[0097] 1-2. Method for manufacturing an all-solid-state battery

[0098] 75 wt% of cathode active material and 22 wt% of the sulfide-based solid electrolyte of Example 1-1, and Super C as a conductive material 65A mixed paste was prepared by thoroughly mixing 3 wt% with a solvent containing a small amount of dissolved binder. An electrode plate was manufactured using the mixed paste and dried to produce a composite electrode plate for the anode. First, 100 mg of a solid electrolyte functioning as a separator was loaded into a jig for all-solid-state battery evaluation, and pressure was applied at over 300 MPa to achieve a thickness of approximately 800 μm. Then, an anode plate was placed on one side, and a secondary pressure was applied to fabricate the anode section. Subsequently, a Li-In alloy was placed on the other side, and an appropriate pressure was applied to fabricate the all-solid-state battery.

[0099] Examples 2 to 11

[0100] Method for manufacturing sulfide-based solid electrolytes

[0101] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1-1, except that a pelletizer comprising a plurality of cylindrical rollers having the rotational speed (rpm), gap between rollers (μm), pattern diameter (mm), and pattern depth (mm) as listed in Table 1 below was used, and the mixture was prepared based on the mixer and pelletizer iterations as listed in Table 1 below.

[0102] All-solid-state battery

[0103] All-solid-state batteries were manufactured in the same manner as in Examples 1-2, except that the sulfide-based solid electrolytes of Examples 2 to 7, manufactured under the conditions of Table 1 below, were used.

[0104] Comparative Example 1

[0105] 1-1. Method for manufacturing sulfide-based solid electrolytes

[0106] Li2S, P2S5, and LiCl were mixed at 300 rpm for about 10 hours using a planetary mill, then pellets were prepared at 300 MPa and synthesized by heat treatment at 500°C in an Ar atmosphere.

[0107] 1-2. Method for manufacturing an all-solid-state battery

[0108] It was prepared in the same manner as Example 1-2, except that the sulfide-based solid electrolyte of Comparative Example 1-1 was used.

[0109] Comparative Examples 2 to 7

[0110] Method for manufacturing sulfide-based solid electrolytes

[0111] A sulfide-based solid electrolyte was prepared in the same manner as in Example 1-1, except that a pelletizer with the rotational speed (rpm), roller gap (μm), pattern diameter (mm), and pattern depth (mm) listed in Table 1 below was used, and the mixture was prepared based on the mixer and pelletizer iterations listed in Table 1 below.

[0112] Method for manufacturing all-solid-state batteries

[0113] All-solid-state batteries were manufactured in the same manner as in Examples 1-2, except that sulfide-based solid electrolytes of Comparative Examples 2 to 5, manufactured under the conditions of Table 1 below, were used.

[0114] Experimental Example 1 Evaluation of ionic conductivity (30℃, 0.1C)

[0115] An experiment to evaluate the ionic conductivity of a solid electrolyte was conducted using a pressure powder cell with a sulfide-based solid electrolyte prepared according to one embodiment and a comparative example of the present invention. Specifically, the synthesized solid electrolyte was ground and then formed into a pellet shape under a pressure of 300 MPa. Subsequently, a cell was fabricated using SUS as the working electrode under a pressure of 70 MPa. Then, the impedance was measured by applying a voltage of 10 mV at 30°C, and the results are shown in Table 1.

[0116] Rotation speed of composition roller (rpm) Gap between rollers (um) Granule pattern diameter Granule pattern depth Iteration (number of dry-pelletizer iterations) Ionic conductivity (mS / cm) Comparative Example 1 Li6PS5Cl ---- 11.9 Comparative Example 2 Li6PS5Cl -3BO 1253312 Comparative Example 3 Li6PS5Cl -3BO 3253312.1 Comparative Example 4 Li6PS5Cl -3BO 5253312 Comparative Example 5 Li6PS5Cl -3BO 10253311.9 Comparative Example 6 Li6PS5Cl -3BO 32530.1 11.9 Comparative Example 7 Li6PS5Cl -3BO 32530.1 101.9 Example 1 Li6PS5Cl -3BO 32531.5 12.4 Example 2 Li6PS5Cl -3BO3253112.5 Example 3Li6PS5Cl -3BO32530.512.5 Example 4Li6PS5Cl -3BO32531.522.6 Example 5Li6PS5Cl -3BO32531.532.7 Example 6Li6PS5Cl -3BO32531.542.7 Example 7Li6PS5Cl -3BO32531.552.7 Example 8Li6PS5Cl -3BO52530.512.3 Example 9Li6PS5Cl -3BO102531.012.1 Example 10Li6PS5Cl -3BO32531.5102.7 Example 11Li6PS5Cl -3BO32530.5102.7

[0117] Referring to Table 1, it can be seen that in Examples 1 to 11, when the pattern depth is 0.5 to 1.5 mm, the ionic conductivity is superior compared to Comparative Examples 2 to 7, where the pattern depth is 0.1 mm or 3.0 mm. Furthermore, it can be seen that Examples 1 to 11, in which the solid electrolyte was synthesized using a pelletizer, exhibit superior ionic conductivity compared to Comparative Example 1, in which the solid electrolyte was synthesized using a planetary mill. Through this, it can be confirmed that the quality of the sulfide-based solid electrolyte is improved when the solid electrolyte is synthesized using a pelletizer comprising a plurality of cylindrical rollers. Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to implement various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and such modifications are also naturally included within the scope of the present invention. Therefore, the actual scope of rights of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. A step of preparing raw materials by mixing a lithium compound, a phosphorus compound, and a halogen compound; A step of forming a mixture by adding a sintered material containing boron to the above raw material; A step of producing pellets by feeding the above mixture into a pelletizer comprising a plurality of cylindrical rollers; and The method includes the step of firing the above pellets in an inert atmosphere, A method for manufacturing a sulfide-based solid electrolyte, wherein the surfaces of the plurality of rollers include a pattern, and the depth of the pattern is 0.2 to 1.8 mm.

2. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the rotational speed of a plurality of cylindrical rollers is 1 to 15 rpm.

3. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the diameter of the above pattern is 1 to 5 mm.

4. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the gap between the plurality of rollers is 10 to 30 μm.

5. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the step of forming the above mixture; and the step of manufacturing the above pellet are repeated 1 to 10 times.

6. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the pelletizer produces pellets by applying a pressure of 100 to 500 MPa.

7. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the calcination temperature of the above calcination step is 300 to 700℃.

8. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the above-mentioned inert atmosphere comprises at least one inert gas selected from argon, hydrogen, nitrogen, helium, neon, xenon, and krypton.

9. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the lithium compound is lithium sulfide (Li2S) and the phosphorus compound is phosphorus pentasulfide (P2S5).

10. In Paragraph 9, The amount of lithium sulfide (Li2S) added is 30 to 50 weight percent based on the total mixture, and A method for manufacturing a sulfide-based solid electrolyte, wherein the amount of phosphorus pentasulfide (P2S5) added is 40 to 50 weight percent based on the total mixture.

11. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the halogen compound comprises at least one of lithium bromide (LiBr), lithium chloride (LiCl), lithium fluoride (LiF), and lithium iodide (LiI).

12. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the amount of the above-mentioned halogen compound added is 10 to 30 weight percent based on the total mixture.

13. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the above-mentioned sintered material comprises at least one of B2O3, H3BO3, Li3BO3, BBr3, and BCl3.

14. In Paragraph 1, A method for manufacturing a sulfide-based solid electrolyte, wherein the amount of the above-mentioned sintered material added is 1 to 5 weight percent based on the total mixture.

15. Sulfide-based solid electrolytes containing lithium (Li), phosphorus (P), sulfur (S), and halogen elements are It comprises 1 to 5 weight percent of B2O3 sintered material, and A sulfide-based solid electrolyte having an ionic conductivity of 2.2 to 4 mS / cm.

16. In Paragraph 15, A sulfide-based solid electrolyte having a molar ratio of lithium (Li) to phosphorus ([P]) ([Li] / [P]) of 5.5 to 7.

0.

17. In Paragraph 15, A sulfide-based solid electrolyte having a molar ratio ([S] / [P]) of sulfur (S) to phosphorus ([P]) of 4.5 to 5.

5.

18. In Paragraph 15, A sulfide-based solid electrolyte having a molar ratio ([D] / [P]) of halogen (D) to phosphorus ([P]) of 0.5 to 1.

5.

19. Bipolar layer; cathode layer; and A solid electrolyte layer interposed between the anode layer and the cathode layer; comprising The above solid electrolyte layer comprises a sulfide-based solid electrolyte according to any one of claims 15 to 18; an all-solid-state battery.

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