Method for preparing composite comprising tin, carbon, and solid electrolyte, all-solid-state battery anode material comprising composite prepared thereby, and all-solid-state battery comprising same

Abstract

The present invention relates to a method for preparing a tin / carbon / solid electrolyte composite, the method comprising the steps of: (a) applying high mechanical energy to a mixture of tin and a carbon-based material to prepare a tin / carbon composite in which nanocrystalline tin is evenly dispersed in the carbon-based material; and (b) applying low mechanical energy to a mixture of the prepared tin / carbon composite and a solid electrolyte to form stable and excellent interfacial contact between the tin / carbon composite and the solid electrolyte while maintaining the crystallinity of the solid electrolyte, thereby preparing a tin / carbon / solid electrolyte composite having high ion conductivity.

Description

Method for producing a composite comprising tin, carbon and a solid electrolyte, a cathode material for an all-solid-state battery comprising the composite produced thereby, and an all-solid-state battery comprising the same

[0001] The present invention relates to a method for producing a negative electrode material for an all-solid-state battery, a negative electrode material for an all-solid-state battery produced thereby, and an all-solid-state battery including the same.

[0002] Lithium secondary batteries have superior cycle life, energy density, and power density compared to other secondary battery systems, and are widely used in fields such as IT, communications, and transportation. However, because lithium secondary batteries use liquid electrolytes containing flammable organic solvents, leakage from external impacts can lead to fire and explosion. Therefore, to alleviate these social concerns about the use of lithium secondary batteries, research into developing secondary battery systems with significantly higher safety and energy densities than lithium secondary batteries is attracting significant international attention. Among these, all-solid-state batteries, energy storage systems that replace liquid electrolytes with flame-retardant solid electrolytes, are emerging as a key research topic due to their potential to achieve both high safety and high energy density. While research on solid electrolytes and anodes with high ionic conductivity is actively underway and has yielded significant results, research on anode materials for all-solid-state batteries remains scarce. Lithium metal anodes, which are considered representative anode materials for all-solid-state batteries, can exhibit high energy density due to their low reaction potential (-3.04 V vs. SHE) and high capacity (3860 mAh / g). However, there are reports of problems in which lithium dendrites grow along the solid electrolyte particle interface during repeated charging and discharging, causing electrical short-circuiting.

[0003] Therefore, the development of anode materials with high capacity, excellent cycle life characteristics, and superior output characteristics is urgently needed for the commercialization of all-solid-state batteries. Recently, lithium alloy-based anode materials that can form an electrochemical alloy phase with lithium and exhibit high capacity have attracted much attention as candidates for high-performance anode materials for all-solid-state batteries. Conventional all-solid-state battery anode layers utilizing alloy-based anode materials are manufactured through a simple mixing process of anode active materials, carbon-based materials, and solid electrolytes. However, this process causes loss of contact with the solid electrolyte, which serves as an ion transport medium, due to volume expansion and contraction of the anode active materials during charging and discharging, resulting in rapid performance degradation.

[0004] Therefore, a manufacturing process for the cathode layer that effectively suppresses the volume change problem of the alloy cathode material, maintains interfacial contact between the cathode active material, carbon, and solid electrolyte for a long period of time during the reaction, and does not destroy the crystallinity of the solid electrolyte, thereby maintaining excellent ionic conductivity of the solid electrolyte, is essential for the development of high-performance cathode materials and the commercialization of all-solid-state batteries.

[0005] The present invention aims to provide a method for producing a tin / carbon / solid electrolyte composite having stable and excellent interfacial contact between tin, carbon, and a solid electrolyte and high ionic conductivity while maintaining the crystallinity of the solid electrolyte, an anode material for an all-solid-state battery including the composite produced thereby, and an all-solid-state battery including the same.

[0006] In order to solve the above problem, the present invention provides a method for producing a tin / carbon / solid electrolyte composite, comprising the steps of (a) applying high mechanical energy to a mixture of tin and a carbon-based material to produce a tin / carbon composite in which nanocrystalline tin is evenly dispersed in the carbon-based material, and (b) applying low mechanical energy to a mixture of the tin / carbon composite produced above and a solid electrolyte to produce a tin / carbon / solid electrolyte composite having high ionic conductivity by maintaining the crystallinity of the solid electrolyte as it is and having stable and excellent interfacial contact between the solid electrolyte and the tin / carbon composite.

[0007] The present invention provides a method for manufacturing a composite, characterized in that the carbon-based material introduced in the above step (a) is at least one selected from the group consisting of vapor-grown carbon fiber (VGCF), carbon nanofiber (CNF), carbon nanotube (CNT), acetylene black, ethylene black, Super P black, carbon black, graphene, Denka black, activated carbon, graphite, hard carbon, or soft carbon.

[0008] In addition, the step (a) provides a method for manufacturing a composite, characterized in that high mechanical energy of 500 rpm or more and 5000 rpm or less is applied using a high-energy spex mill, a vibrotary mill, a Z-mill, a planetary ball-mill, a vortex mill, or an attrition mill.

[0009] In addition, a method for producing a composite is provided, characterized in that the composite is produced in step (a) containing 10 wt% to 90 wt% of tin and 10 wt% to 90 wt% of carbon (C).

[0010] In addition, a method for producing a composite is provided, characterized in that a composite in powder form having a particle size of an average diameter of 1 nm or more and less than 500 μm is produced in the step (a).

[0011] In addition, a method for producing a composite is provided, characterized in that in the step (a), a composite in the form of a powder in which tin crystal grains having an average diameter of 1 nm or more and less than 100 nm are well dispersed in carbon is produced.

[0012] The solid electrolyte introduced in the above step (b) is classified into (1) a sulfide-based solid electrolyte and (2) an oxide-based solid electrolyte. (1) The sulfide-based solid electrolyte is Li2S-P2S55, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2OLiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2SB2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is P, Si, Ge, B, Al, Ga or In) and Li a M b P c S d Z e(0 <a≤20, 0≤b≤6, 0<c≤6, 0<d≤20, 0≤e≤9, M은 B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta 또는 W, Z는 F, Cl, Br, I 또는 O) 등으로 이루어지는 분말 중 1종 이상의 분말을 사용할 수 있다. 또한, (2) 산화물계 고체전해질은 Li x Al p Ga q La y Zr z O 12 (5≤x≤9, 0≤p≤4, 0≤q≤4, 2≤y≤4, 1≤z≤3), Li 7-x M x La3Zr 2-x O 12 (M is Ta, Y, Sc, or Nb, and x < 0.7), Li x Ga w La y Zr z Sc m O 12 (5≤x≤9, 2≤y≤4, 1≤z≤3, 0 <w≤1, 0<m≤1), Li7La3Sn2O 12 , Li6La3Ta 1.5 Y 0.5 O 12 , Li x Si y O z (1≤f≤5, 0 <y≤3, 1≤z≤10), Li x S y O z (1≤x≤3, 0 <y≤2, 1≤z≤10), Li3BO3-Li2SO4, Li2O-B2O3-P2O5, Li2O-SiO2, Li6BaLa2Ta2O 12 , Li3PO (4-3 / 2w) N w (w<1) and Li 3.5 Zn 0.25 One or more types of powders made of GeO4, etc. can be used.

[0013] In addition, the step (b) provides a method for manufacturing a composite, characterized in that low mechanical energy of less than 500 rpm is applied using a vibrotary mill, a Z-mill, a planetary ball-mill, a vortex mill, or an attrition mill.

[0014] In addition, a method for producing a composite is provided, characterized in that the composite is produced in step (b) by including 30 wt% to 90 wt% of a tin / carbon composite and 10 wt% to 70 wt% of a solid electrolyte.

[0015] In addition, a method for producing a composite is provided, characterized in that a composite in powder form having a particle size of an average diameter of 1 nm or more and less than 500 μm is produced in the step (b).

[0016] And, in another aspect of the present invention, there is provided an anode material for an all-solid-state battery comprising a composite comprising tin / carbon / solid electrolyte manufactured by the above manufacturing method.

[0017] And, in another aspect of the present invention, the present invention provides a lithium-ion all-solid-state battery including the negative electrode material.

[0018] In addition, an all-solid-state battery is provided, characterized in that it is an all-solid-state battery having a reaction potential of 0 V or more and 3 V or less compared to lithium.

[0019] According to the method for producing a tin / carbon / solid electrolyte composite according to the present invention, a tin / carbon / solid electrolyte composite can be produced simply and efficiently using a simple solid synthesis method that applies mechanical energy without going through a complicated and inefficient process such as a chemical method.

[0020] In addition, according to the manufacturing method according to the present invention, a tin / carbon composite in which tin in the form of nanocrystals is evenly dispersed in carbon is manufactured by applying high mechanical energy through a ball milling process capable of applying high mechanical energy, and then, through a ball milling process capable of applying low mechanical energy, low mechanical energy is applied to a mixture of the tin / carbon composite and the solid electrolyte to maintain the crystallinity of the solid electrolyte as it is, thereby manufacturing a tin / carbon / solid electrolyte composite having high ionic conductivity and excellent contact characteristics between the solid electrolyte and the tin / carbon composite.

[0021] In addition, when the tin / carbon / solid electrolyte composite manufactured by the above method is applied as an anode material for an all-solid-state battery, problems such as reduced lifespan due to volume change that appear in existing alloy electrode materials for secondary batteries can be solved, and a high-performance all-solid-state battery system having high capacity, high lifespan, and high output can be implemented by maintaining high ionic conductivity.

[0022] FIG. 1 is a conceptual diagram illustrating a manufacturing process of a tin / carbon / solid electrolyte composite according to one embodiment of the present invention.

[0023] FIG. 2a is a schematic diagram of a half-cell of an all-solid-state battery comprising a tin / carbon / solid electrolyte composite according to the present invention.

[0024] Figure 2b is a full cell schematic diagram of an all-solid-state battery comprising a tin / carbon / solid electrolyte composite according to the present invention as a negative electrode active material.

[0025] Figure 3a is a graph showing the results of X-ray diffraction analysis of a tin / carbon composite according to the present invention.

[0026] Figure 3b is a graph showing the results of X-ray diffraction analysis of a tin / carbon / solid electrolyte composite according to the present invention.

[0027] Figure 4 is a graph showing the results of X-ray diffraction analysis of a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process commonly used according to a comparative example of the present invention.

[0028] FIG. 5 is a graph showing the results of X-ray diffraction analysis of a tin / carbon / solid electrolyte composite manufactured at once by applying low mechanical energy (200 rpm) to a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) according to a comparative example of the present invention.

[0029] FIG. 6 is a graph showing the results of X-ray diffraction analysis of a tin / carbon / solid electrolyte composite manufactured at once by applying high mechanical energy (1000 rpm) to a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) according to a comparative example of the present invention.

[0030] Figure 7a is a graph showing the results of a charge / discharge experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid-state electrolyte composite according to the present invention as an electrode active material of a half-cell of the all-solid-state battery.

[0031] Figure 7b is a graph showing the results of a cycle life experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid-state electrolyte composite according to the present invention as an electrode active material of a half-cell of the all-solid-state battery.

[0032] Figure 8a is a graph showing the results of a charge / discharge experiment of a lithium-ion all-solid-state battery including a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process commonly used according to a comparative example of the present invention as an electrode active material of a half-cell of the all-solid-state battery.

[0033] Figure 8b is a graph showing the results of a cycle life experiment of an all-solid-state battery including a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process commonly used according to a comparative example of the present invention as an electrode active material of an all-solid-state battery half cell.

[0034] Figure 9a is a graph showing the results of a charge / discharge experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid electrolyte composite manufactured at once by applying low mechanical energy (200 rpm) according to a comparative example of the present invention as an electrode active material of a half-cell of the all-solid-state battery.

[0035] Figure 9b is a graph showing the results of a cycle life experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid electrolyte composite manufactured at once by applying low mechanical energy (200 rpm) according to a comparative example of the present invention as an electrode active material of an all-solid-state battery half cell.

[0036] Figure 10a is a graph showing the results of a charge / discharge experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid electrolyte composite manufactured at once by applying high mechanical energy (1000 rpm) according to a comparative example of the present invention as an electrode active material of a half cell of the all-solid-state battery.

[0037] Figure 10b is a graph showing the results of a cycle life experiment of a lithium-ion all-solid-state battery including a tin / carbon / solid electrolyte composite manufactured at once by applying high mechanical energy (1000 rpm) according to a comparative example of the present invention as an electrode active material of an all-solid-state battery half cell.

[0038] Figure 11a shows a tin / carbon / solid electrolyte composite according to the present invention, with a negative electrode active material, LiNi. 0.6 Co 0.2 Mn 0.2 This is a graph showing the results of a charge / discharge experiment on a full cell of a lithium-ion all-solid-state battery using O2 as the cathode active material.

[0039] Figure 11b shows a tin / carbon / solid electrolyte composite according to the present invention, with a negative electrode active material, LiNi. 0.6 Co 0.2 Mn 0.2 This is a graph showing the cycle life test results of a full cell of a lithium-ion all-solid-state battery using O2 as the cathode active material.

[0040] In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0041]

[0042] Embodiments according to the concept of the present invention may be modified in various ways and take various forms. Therefore, specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to specific disclosed forms, and it should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0043]

[0044] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a described feature, number, step, operation, component, part, or combination thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0045]

[0046] Hereinafter, the present invention will be described in detail.

[0047]

[0048] The cathode layer for a typical all-solid-state battery is manufactured through a simple mixing process of cathode active material, carbon, and a solid electrolyte. However, cathode layers manufactured through this process easily lose contact with the solid electrolyte, which serves as a medium for ion transport, due to volume changes in the cathode active material that occur during charging and discharging. This leads to a persistent increase in interfacial resistance and a rapid deterioration in battery performance.

[0049] Therefore, in order to secure high performance of all-solid-state batteries, it is urgent to develop a manufacturing process that effectively suppresses volume change of alloy-based negative electrode materials, thereby maintaining stable and excellent contact between the negative electrode active material, carbon, and solid electrolyte constituting the negative electrode layer for a long period of time even during repeated electrochemical reactions, and that does not affect the crystallinity of the solid electrolyte within the negative electrode layer during the negative electrode layer manufacturing process, thereby maintaining high ionic conductivity.

[0050] Accordingly, the inventors of the present invention have developed a cathode material for an all-solid-state battery and a method for manufacturing the same that can solve the above-described problems.

[0051]

[0052] A method for manufacturing a tin / carbon / solid electrolyte composite anode material for an all-solid-state battery according to the present invention comprises the steps of: (a) applying high mechanical energy to a mixture of tin and a carbon-based material to manufacture a tin / carbon composite in which nanocrystalline tin is evenly dispersed in the carbon-based material; and (b) applying low mechanical energy to a mixture of the manufactured tin / carbon composite and a solid electrolyte to manufacture a tin / carbon / solid electrolyte composite having high ionic conductivity while maintaining the crystallinity of the solid electrolyte and excellent contact characteristics between the solid electrolyte and the tin / carbon composite.

[0053] The above step (a) is a step of applying high mechanical energy to a mixture of the above tin and carbon-based material to produce a tin / carbon composite in which tin nanocrystals are evenly dispersed in carbon.

[0054] The carbon-based material powder introduced in the above step (a) may be selected from at least one selected from vapor-grown carbon fiber (VGCF), carbon nanofiber (CNF), carbon nanotube (CNT), acetylene black, ethylene black, Super P black, carbon black, graphene, Denka black, activated carbon, graphite, hard carbon, or soft carbon. These carbon components form a battery conduction channel to improve the conductivity of the negative electrode material and effectively suppress agglomeration.

[0055] The above step (a) is a process that applies high mechanical energy of 500 rpm or more and 5000 rpm or less (500 to 5000 times per minute), and can be performed by any known ball milling device used for a ball milling process capable of applying high mechanical energy, such as a high-energy spex mill, a vibrotary mill, a Z-mill, a planetary ball-mill, a vortex mill, or an attrition mill.

[0056] In the above step (a), a ball milling process capable of applying high mechanical energy is performed to manufacture a tin / carbon composite in which tin in the form of nanocrystals is evenly dispersed in carbon, which is very effective in suppressing the volume change problem of alloy-based negative electrode materials for secondary batteries.

[0057] Meanwhile, a more specific method for manufacturing a tin / carbon composite according to the present invention through a solid synthesis method using high-energy ball milling is as follows.

[0058] First, tin and carbon are placed in a cylindrical vial together with balls and placed in a high-energy ball mill, and mechanical synthesis is performed at a rotation speed of 500 to 5,000 rotations per minute to produce a tin / carbon composite in which nanocrystalline tin is evenly dispersed in the carbon. The time for performing the ball milling is not particularly limited, but it is preferably performed for 10 minutes to 24 hours. Here, the weight ratio of the balls to the mixture is maintained at, for example, 10:1 to 30:1, and the mechanical synthesis is prepared in a glove box under an argon gas atmosphere to suppress the influence of oxygen and moisture as much as possible.

[0059] As described above, by using a solid-state synthesis method using high-energy ball milling, a tin / carbon composite can be simply and efficiently manufactured without performing a conventional chemical synthesis method.

[0060] Meanwhile, the tin / carbon composite containing the above tin and carbon (C) is characterized by containing 10 wt% to 90 wt% of tin and 10 wt% to 90 wt% of carbon (C), and preferably has a particle size of 1 nm to less than 500 μm in average diameter and a powder form in which tin crystal grains having an average diameter of 1 nm to less than 100 nm are well dispersed in carbon.

[0061] Next, the step (b) is a step of applying low mechanical energy to a mixture of the tin / carbon composite and the solid electrolyte manufactured above, thereby maintaining the crystallinity of the solid electrolyte and having high ionic conductivity, and manufacturing a tin / carbon / solid electrolyte composite having excellent contact characteristics between the solid electrolyte and the tin / carbon composite.

[0062] The solid electrolyte powders used in this step (b) are classified into (1) sulfide-based solid electrolytes and (2) oxide-based solid electrolytes. (1) Sulfide-based solid electrolytes include Li2S-P2S55, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2OLiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2SB2S3, and Li2S-P2S5-Z. m S n (m, n are positive numbers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is P, Si, Ge, B, Al, Ga or In) and Li a M b P c S d Z e (0 <a≤20, 0≤b≤6, 0<c≤6, 0<d≤20, 0≤e≤9, M은 B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta 또는 W, Z는 F, Cl, Br, I 또는 O) 등으로 이루어지는 분말 중 1종 이상의 분말을 사용할 수 있다. 또한, (2) 산화물계 고체전해질은 Li x Al p Ga q La y Zr z O 12 (5≤x≤9, 0≤p≤4, 0≤q≤4, 2≤y≤4, 1≤z≤3), Li 7-x M x La3Zr 2-x O 12 (M is Ta, Y, Sc, or Nb, and x < 0.7), Li x Gaw La y Zr z Sc m O 12 (5≤x≤9, 2≤y≤4, 1≤z≤3, 0 <w≤1, 0<m≤1), Li7La3Sn2O 12 , Li6La3Ta 1.5 Y 0.5 O 12 , Li x Si y O z (1≤f≤5, 0 <y≤3, 1≤z≤10), Li x S y O z (1≤x≤3, 0 <y≤2, 1≤z≤10), Li3BO3-Li2SO4, Li2O-B2O3-P2O5, Li2O-SiO2, Li6BaLa2Ta2O 12 , Li3PO (4-3 / 2w) N w (w<1) and Li 3.5 Zn 0.25 One or more types of powders made of GeO4, etc. can be used.

[0063] In the above step (b), the process of applying low mechanical energy of less than 500 rpm, more preferably 100 rpm or more and less than 500 rpm, can be performed by any known ball milling device used for a ball milling process capable of applying low mechanical energy, such as a vibrotary mill, a Z-mill, a planetary ball-mill, a vortex mill, or an attrition mill. At this time, the time for performing the ball milling is not particularly limited, but it is preferably performed for 1 minute to 1 hour.

[0064] In step (b), if high mechanical energy is applied, the crystallinity of the solid electrolyte decreases, leading to a rapid decrease in ionic conductivity. Therefore, a ball milling process capable of applying low mechanical energy must be performed to produce a uniformly dispersed tin / carbon / solid electrolyte composite that maintains the crystallinity of the solid electrolyte, exhibits high ionic conductivity, and forms excellent contact with the tin / carbon composite.

[0065]

[0066] Figure 1 is a conceptual diagram schematically illustrating the process of manufacturing a tin / carbon complex and synthesizing a tin / carbon / solid electrolyte complex.

[0067] The tin / carbon / solid electrolyte composite manufactured by the above-described manufacturing method maintains excellent contact and can effectively suppress the volume change problem of tin, so it has high capacity, long life, and high output characteristics, and is therefore very suitable for use as an electrode active material for an all-solid-state battery.

[0068] Meanwhile, the tin / carbon / solid electrolyte complex including the tin / carbon complex and the solid electrolyte is characterized by including 30 wt% to 90 wt% of the tin / carbon complex and 10 wt% to 70 wt% of the solid electrolyte, and preferably has a powder form with an average diameter of 1 nm to less than 500 μm.

[0069] By using a solid synthesis method using a ball milling process that applies mechanical energy as described above, a tin / carbon / solid electrolyte composite can be manufactured simply and efficiently without performing a conventional chemical synthesis method.

[0070] Furthermore, the present invention provides an all-solid-state battery comprising the tin / carbon / solid electrolyte composite.

[0071] Figure 2a is a schematic diagram of a half cell of an all-solid-state battery comprising a tin / carbon / solid electrolyte composite according to the present invention as an electrode active material.

[0072] The half-cell (1) of the above-described all-solid-state battery includes a negative electrode layer (10); a lithium-indium foil (20); and a solid electrolyte layer (30) disposed between the negative electrode layer (10) and the lithium-indium foil (20). The negative electrode layer (10) includes a negative electrode current collector (11) and a negative electrode active material (12), carbon (111), and a solid electrolyte (112) disposed on the negative electrode current collector (11), and the negative electrode layer (10) includes a negative electrode material including the tin / carbon / solid electrolyte composite. The half-cell of the above-described all-solid-state battery can be manufactured by sequentially laminating the solid electrolyte layer (30), the negative electrode layer (10), and the lithium-indium foil (20).

[0073] The negative electrode current collector (11) is composed of a material that does not react with lithium, i.e., does not form an alloy or compound. The material constituting the negative electrode current collector (11) includes, for example, a plate or foil made of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), or an alloy thereof. The negative electrode current collector (11) may be omitted.

[0074] Figure 2b is a full cell schematic diagram of an all-solid-state battery comprising a tin / carbon / solid electrolyte composite according to the present invention as a negative electrode active material.

[0075] The full cell (2) of the above-described all-solid-state battery includes a positive electrode layer (40); a negative electrode layer (10); and a solid electrolyte layer (30) disposed between the positive electrode layer (40) and the negative electrode layer (10). The positive electrode layer (40) includes a positive electrode current collector (41) and a positive electrode active material (42), carbon (111), and a solid electrolyte (112) disposed on the positive electrode current collector (41). The negative electrode layer (10) includes a negative electrode current collector (11) and a negative electrode active material (12), carbon (111), and a solid electrolyte (112) disposed on the negative electrode current collector (11). The negative electrode layer (10) includes a negative electrode material including the tin / carbon / solid electrolyte composite. The full cell of the above-described all-solid-state battery can be manufactured by sequentially stacking the solid electrolyte layer (30), the positive electrode layer (40), and the negative electrode layer (10).

[0076] The positive electrode collector (41) uses 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), or an alloy thereof. The positive electrode collector (41) may be omitted.

[0077] The cathode active material is a cathode active material that can reversibly absorb and desorb lithium ions. Examples of the cathode active material include, but are not limited to, 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, and any material used as a cathode active material in the relevant technical field may be used. The cathode active materials may be singly or in a mixture of two or more.

[0078] Lithium transition metal oxides include, for example, Li a A 1-b B b D2 (in the above formula, 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 O 4-c D c (In the above formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c D α (In the above formula, 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 formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Lia Ni 1-b-c Co b B c O 2-α F2 (in the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0 <α<2); Li a N i1-b-c Mn b B c D α (In the above formula, 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 formula, 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 (in the above formula, 0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2 (in the above formula, 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 (in 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 formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a CoG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a MnG b O2 (in the above formula, 0.90≤a≤1, 0.001≤b≤0.1); Li a Mn2G bO4 (in the above formula, 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 this 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; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. It is also possible to use a compound having a coating layer added to the surface of this compound, and it is also possible to use a mixture of the above-mentioned compound and the compound having a coating layer added. The coating layer added to the surface of such a compound includes a coating element compound of, for example, an oxide, a hydroxide, an oxyhydroxide of the coating element, an oxycarbonate of the coating element, or a hydroxycarbonate of the coating element of the coating element. The compound forming the coating layer is amorphous or crystalline. The coating elements included in the coating layer include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method includes, for example, spray coating, dipping, etc.

[0079] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosure is thorough and complete and to sufficiently convey the spirit of the present invention to those skilled in the art.

[0080]

[0081] <Example> Preparation of a tin / carbon / solid electrolyte composite and an all-solid-state battery containing the same

[0082] (1) Preparation of tin / carbon / solid electrolyte complex

[0083] A tin / carbon composite was prepared by applying high mechanical energy (1000 rpm) to a mixture of tin and carbon (C) for 1 hour through a ball milling process capable of applying high mechanical energy. Next, a tin / carbon / solid electrolyte composite was prepared by applying low mechanical energy (200 rpm) to a mixture of the prepared tin / carbon composite and a sulfide-based solid electrolyte (Li6PS5Cl) for 10 minutes through a ball milling process capable of applying low mechanical energy.

[0084] A ball milling process that applies high mechanical energy for the production of a tin / carbon composite can produce a tin / carbon composite in which nanocrystalline tin is evenly dispersed in carbon, which can effectively suppress the volume change problem of alloy-based anode materials for secondary batteries. The mechanical energy (500 rpm to 5000 rpm) and ball milling time of the ball milling process can be set to optimal conditions depending on the type of ball milling device so that nanocrystalline tin with a size of 1 nm to 100 nm can be evenly dispersed in carbon.

[0085] In addition, the ball milling process applying low mechanical energy for the production of a tin / carbon / solid electrolyte composite can produce a uniformly dispersed tin / carbon / solid electrolyte composite having high ionic conductivity by maintaining the crystallinity of the solid electrolyte and forming excellent contact with the tin / carbon composite. For reference, when the ball milling process applying high mechanical energy for the production of a tin / carbon / solid electrolyte composite is performed, the ionic conductivity decreases due to the loss of crystallinity of the solid electrolyte, thereby deteriorating battery performance.

[0086] The mechanical energy (less than 500 rpm) and ball milling time of the above ball milling process can be set to optimal conditions depending on the type of ball milling device so that the crystallinity of the solid electrolyte is maintained as it is, so that it has high ionic conductivity, and so that it can be uniformly distributed while forming excellent contact between the solid electrolyte and the tin / carbon complex.

[0087] Figures 3a and 3b are graphs showing the results of X-ray diffraction analysis of a tin / carbon composite containing tin and carbon (C) and a tin / carbon / solid electrolyte composite containing the tin / carbon composite and a solid electrolyte (Li6PS5Cl).

[0088] Figure 4 is a graph showing the results of X-ray diffraction analysis of a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process using a mortar and pestle according to the comparison of the present invention.

[0089] FIG. 5 is a graph showing the results of X-ray diffraction analysis of a tin / carbon / solid electrolyte composite manufactured at once by applying low mechanical energy (vortex-mill, 200 rpm) to a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) according to the comparison of the present invention.

[0090] Figure 6 is a graph showing the results of X-ray diffraction analysis of a tin / carbon / solid electrolyte composite manufactured at once by applying high mechanical energy (Spex mill, 1000 rpm) to a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) according to the comparison of the present invention.

[0091]

[0092] (2) Evaluation of the initial efficiency characteristics, cycle characteristics, and high-rate characteristics of the manufactured tin / carbon / solid electrolyte composite and the all-solid-state battery containing the same.

[0093] Figures 7a and 7b are graphs showing the results of electrochemical charge / discharge experiments and cycle life experiments of half cells of an all-solid-state battery of a tin / carbon / solid electrolyte composite manufactured in the present invention.

[0094] Figure 7a is a graph showing the experimental results for the charge and discharge capacity of a tin / carbon / solid electrolyte composite. The graph shows the charge and discharge behavior for the 1st, 2nd, 5th, 10th, 50th, and 100th cycles, respectively, when the tin / carbon / solid electrolyte composite was applied as a half-cell electrode material for an all-solid-state battery. The charge and discharge capacities for the first cycle were 1025 mAh / g and 849 mAh / g, respectively, and the efficiency for the initial cycle was approximately 83%.

[0095] Figure 7b is a graph showing the results of a cycle life characteristic experiment of a tin / carbon / solid electrolyte composite. When the tin / carbon / solid electrolyte composite of the present invention is applied as a half-cell electrode material of an all-solid-state battery, it exhibits excellent cycle life characteristics without any change in capacity even for several cycles at a reaction potential of 0 V to 2 V.

[0096] Figures 8a and 8b are graphs showing the results of electrochemical charge-discharge experiments and cycle life experiments of an all-solid-state battery half cell of a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process using a commonly manufactured mortar.

[0097] Figure 8a is a graph showing the experimental results for the charge and discharge capacity of a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process using a commonly manufactured mortar. The graph shows the charge and discharge behavior for the 1st, 2nd, 5th, 10th, and 20th cycles, respectively, when the mixture is applied as a half-cell electrode material for an all-solid-state battery. The charge and discharge capacities of the 1st cycle were 979 mAh / g and 705 mAh / g, respectively, and the efficiency of the initial cycle was approximately 72%.

[0098] Figure 8b is a graph showing the results of a cycle life characteristic experiment of a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl) manufactured by a simple mixing process using a commonly manufactured mortar and pestle. When the mixture is applied as a half-cell electrode material of an all-solid-state battery, it shows a rapid capacity decrease compared to the tin / carbon / solid-state electrolyte composite of the present invention.

[0099] Figures 9a and 9b are graphs showing the results of electrochemical charge-discharge experiments and cycle life experiments of half cells of an all-solid-state battery of a tin / carbon / solid-state electrolyte composite manufactured at once by applying low mechanical energy (vortex-mill, 200 rpm, 10 min) to a mixture of tin, carbon (C), and solid electrolyte (Li6PS5Cl).

[0100] Figure 9a is a graph showing the experimental results of the charge and discharge capacities of a tin / carbon / solid electrolyte composite manufactured at one time by applying low mechanical energy (vortex-mill, 200 rpm, 10 min) of tin, carbon (C), and a solid electrolyte (Li6PS5Cl). The graph shows the charge and discharge behaviors for the 1st, 2nd, 5th, 10th, and 20th cycles, respectively, when the composite is applied as a half-cell electrode material for an all-solid-state battery. The charge and discharge capacities of the 1st cycle were 914 mAh / g and 708 mAh / g, and the efficiency of the initial cycle was approximately 77%.

[0101] FIG. 9b is a graph showing the cycle life characteristics of a tin / carbon / solid electrolyte composite manufactured at once by applying low mechanical energy (vortex-mill, 200 rpm, 10 minutes) to a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl). When the composite is applied as a half-cell electrode material of an all-solid-state battery, it shows a rapid capacity decrease compared to the tin / carbon / solid electrolyte composite of the present invention.

[0102] Figures 10a and 10b are graphs showing the results of electrochemical charge-discharge experiments and cycle life experiments on half cells of an all-solid-state battery of a tin / carbon / solid-state electrolyte composite manufactured at once by applying high mechanical energy (spex mill, 1000 rpm, 1 hour) to a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl).

[0103] Figure 10a is a graph showing the experimental results of charge and discharge capacities of a tin / carbon / solid electrolyte composite manufactured at one time by applying high mechanical energy (spex mill, 1000 rpm, 1 hour) to a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl). The graph shows the charge and discharge behaviors for the 1st, 2nd, 5th, 10th, 20th, 30th, 40th, and 50th cycles, respectively, when the composite was applied as a half-cell electrode material for an all-solid-state battery. The charge and discharge capacities of the 1st cycle were 1019 mAh / g and 783 mAh / g, and the efficiency of the initial cycle was approximately 77%.

[0104] FIG. 10b is a graph showing the cycle life characteristics of a tin / carbon / solid electrolyte composite manufactured at once by applying high mechanical energy (spex mill, 1000 rpm, 1 hour) to a mixture of tin, carbon (C), and a solid electrolyte (Li6PS5Cl). When the composite is applied as a half-cell electrode material of an all-solid-state battery, it shows a rapid capacity decrease compared to the tin / carbon / solid electrolyte composite of the present invention.

[0105] Table 1 below summarizes the electrochemical performances of the tin / carbon / solid electrolyte composite of the present invention, the tin / carbon / solid electrolyte mixture manufactured by a simple mixing process commonly used, the tin / carbon / solid electrolyte composite manufactured at once by a low-energy ball milling process (vortex-mill, 200 rpm, 10 minutes), and the tin / carbon / solid electrolyte composite manufactured at once by a high-energy ball milling process (spex mill, 1000 rpm, 1 hour).

[0106]

[0107]

[0108]

[0109] Figures 11a and 11b show the tin / carbon / solid electrolyte composite manufactured in the present invention, with the negative electrode active material, LiNi. 0.6 Co 0.2 Mn 0.2 This is a graph showing the results of electrochemical charge-discharge experiments and cycle life experiments on a full cell of an all-solid-state battery using O2 as the cathode active material.

[0110] Figure 11a shows a composite cathode of tin / carbon / solid electrolyte and LiNi. 0.6 Co 0.2 Mn 0.2 This graph shows the charge and discharge behavior of an all-solid-state battery full cell composed of an O2 cathode for the 1st, 2nd, 5th, 10th, 50th, and 100th cycles, respectively. Even at a fast current density of 320 mA / g, it exhibits an initial charge capacity of 114 mAh / g and an initial discharge capacity of 99 mAh / g.

[0111] Figure 11b shows a tin / carbon / solid electrolyte composite cathode and LiNi 0.6 Co 0.2 Mn 0.2 This graph shows the cycle life characteristics of a full cell of an all-solid-state battery composed of an O2 anode, and shows excellent cycle life characteristics without any change in capacity for several cycles at a reaction potential of 2.5 V to 4.3 V.

[0112] As described above, in the present invention, a tin / carbon / solid electrolyte composite was used as an anode material for a secondary battery, particularly an all-solid-state battery, to implement an all-solid-state battery system having high capacity, long life, and high output characteristics. This is because a tin / carbon composite in which nanocrystalline tin is evenly dispersed in carbon is manufactured by applying high mechanical energy to a mixture of tin and carbon, thereby effectively suppressing the problem of deterioration in life characteristics due to volume change of an alloy-based anode material, and further, by applying low mechanical energy to the mixture of the manufactured tin / carbon composite and the solid electrolyte, the crystallinity of the solid electrolyte is not affected, thereby maintaining high ionic conductivity, and the contact between the solid electrolyte and the tin / carbon composite is greatly improved.

[0113] Accordingly, mechanical stability and excellent contact with solid electrolyte, which are most important in secondary batteries, especially solid-state battery negative electrodes, can be secured, and capacity and cycle life can also be greatly improved.

[0114]

[0115] While the embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics thereof. Therefore, the embodiments described above should be understood to be illustrative in all respects and not restrictive.

[0116]

[0117] <Explanation of symbols>

[0118] 1: Half cell of an all-solid-state battery 2: Full cell of an all-solid-state battery

[0119] 10: Cathode layer 11: Cathode current collector

[0120] 12: Negative active material 20: Lithium-indium foil

[0121] 30: Solid electrolyte layer 40: Anode layer

[0122] 41: Cathode current collector 42: Cathode active material

[0123] 111: Carbon 112: Solid electrolyte

[0124]

[0125] When the tin / carbon / solid electrolyte composite manufactured according to the present invention is applied as an anode material for an all-solid-state battery, problems such as reduced lifespan due to volume change that appear in existing alloy electrode materials for secondary batteries can be solved, and a high-performance all-solid-state battery system having high capacity, high lifespan, and high output can be implemented by maintaining high ionic conductivity.

Claims

1. (a) A step of producing a tin / carbon composite by applying high mechanical energy to a mixture of tin and carbon-based materials: and (b) a step of applying low mechanical energy to a mixture of the tin / carbon composite and the solid electrolyte to produce a tin / carbon / solid electrolyte composite; A method for producing a tin / carbon / solid electrolyte composite comprising:

2. In paragraph 1, The above carbon-based material is, A method for producing a composite, characterized in that the composite comprises at least one selected from the group consisting of vapor-grown carbon fiber (VGCF), carbon nanofiber (CNF), carbon nanotube (CNT), acetylene black, ethylene black, Super P black, carbon black, graphene, Denka black, activated carbon, graphite, hard carbon, and soft carbon.

3. In paragraph 1, The above solid electrolyte is, Li2S-P2S55, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2OLiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2SB2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is P, Si, Ge, B, Al, Ga or In) and Li a M b P c S d Z e (0 <a≤20, 0≤b≤6, 0<c≤6, 0<d≤20, 0≤e≤9, M은 B, Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta 또는 W, Z는 F, Cl, Br, I 또는 O)으로 이루어진 군으로부터 선택되는 1종 이상의 황화물계 고체전해질 또는 Li x Al p Ga q La y Zr z O 12 (5≤x≤9, 0≤p≤4, 0≤q≤4, 2≤y≤4, 1≤z≤3), Li 7-x M x La3Zr 2-x O 12 (M is Ta, Y, Sc, or Nb, and x < 0.7), Li x Ga w La y Zr z Sc m O 12 (5≤x≤9, 2≤y≤4, 1≤z≤3, 0 <w≤1, 0<m≤1), Li7La3Sn2O 12 , Li6La3Ta 1.5 Y 0.5 O 12 , Li x Si y O z (1≤f≤5, 0 <y≤3, 1≤z≤10), Li x S y O z (1≤x≤3, 0 <y≤2, 1≤z≤10), Li3BO3-Li2SO4, Li2O-B2O3-P2O5, Li2O-SiO2, Li6BaLa2Ta2O 12 , Li3PO (4-3 / 2w) N w (w<1) and Li 3.5 Zn 0.25 A method for producing a composite, characterized in that it is a solid electrolyte of one or more oxides selected from the group consisting of GeO4.

4. In paragraph 1, In the above step (a), A method for manufacturing a composite, characterized in that a tin / carbon composite is manufactured by performing high-energy milling on a mixture of tin and carbon-based materials at a rotation speed of 500 to 5000 rpm.

5. In paragraph 1, In the above step (a), A method for producing a composite, characterized by producing a tin / carbon composite containing 10 to 90 wt% of tin and 10 to 90 wt% of carbon (C).

6. In paragraph 1, In the above step (a), A method for producing a composite, characterized in that the composite has a powder form in which tin crystal grains having an average diameter of 1 nm or more and less than 100 nm are uniformly dispersed in carbon, and a tin / carbon composite having a particle size of an average diameter of 1 nm or more and less than 500 μm.

7. In paragraph 1, In the above step (b), A method for producing a composite, characterized in that a tin / carbon / solid electrolyte composite is produced by performing low-energy milling on a mixture of a tin / carbon composite and a solid electrolyte at a rotation speed of less than 500 rpm.

8. In paragraph 1, In the above step (b), A method for producing a composite, characterized by producing a tin / carbon / solid electrolyte composite comprising 30 to 90 wt% of a tin / carbon composite and 10 to 70 wt% of a solid electrolyte.

9. In paragraph 1, In the above step (b), A method for producing a composite, characterized by producing a tin / carbon / solid electrolyte composite in powder form having a particle size of an average diameter of 1 nm or more and less than 500 μm.

10. In paragraph 1, In the above step (b), A method for manufacturing a composite characterized in that there is no change in the crystallinity of a solid electrolyte before and after application of mechanical energy.

11. A negative electrode active material for an all-solid-state battery comprising a tin / carbon / solid electrolyte composite manufactured by the manufacturing method of paragraph 1.

12. A lithium-ion all-solid-state battery comprising the negative electrode active material of Article 11.

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