Positive electrode for all-solid-state lithium-sulfur battery, all-solid-state lithium-sulfur battery comprising same, and method for manufacturing same

Abstract

The present invention relates to a method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, the method comprising the steps of: preparing a carrier including conductive carbon having a transition metal sulfur compound coated on the surface thereof; mixing the carrier and a sulfur raw material and then heating same to prepare a sulfur composite; and mixing the sulfur composite and a sulfide-based solid electrolyte to prepare a mixture, and wet-mixing the mixture by using a polar solvent having a first polarity index, to thereby prepare a powder, wherein the first polarity index is 3 to 5.

Description

Anode for an all-solid-state lithium-sulfur battery, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same

[0001] The present invention relates to a positive electrode for an all-solid-state lithium-sulfur battery, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same, and more specifically, to a positive electrode for an all-solid-state lithium-sulfur battery having improved electrochemical performance and cycle characteristics by being manufactured using a novel method, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same.

[0002] The development of portable electronic devices such as smartphones, MP3 players, and tablet PCs has led to an explosive increase in demand for secondary batteries capable of storing electrical energy. In particular, the emergence of electric vehicles, medium- to large-scale energy storage systems, and portable devices requiring high energy density is driving the demand for secondary batteries.

[0003] Lithium secondary batteries are a type of secondary battery that can be recharged using an external power source. They offer numerous advantages, including high energy density and long lifespan. As the application of lithium secondary batteries expands beyond portable electronic and communication devices to include electric vehicles and power storage devices, demand for higher capacity and lower cost lithium secondary batteries, which serve as power sources for these devices, is increasing.

[0004] Solid electrolytes can be divided into oxide and sulfide types. Because sulfide solid electrolytes have higher lithium ion conductivity than oxide solid electrolytes, sulfide solid electrolytes are primarily used.

[0005] In secondary batteries containing solid electrolytes, the positive electrode is composed of a composite mixture of positive electrode active material and solid electrolyte in a certain ratio. This is to secure ion-conducting channels within the positive electrode. While securing both ion-conducting paths and electrically conductive channels is crucial, solid electrolytes do not possess these channels. Therefore, the positive electrodes of secondary batteries containing solid electrolytes suffer from lower electrical conductivity compared to the positive electrodes of conventional liquid-type secondary batteries.

[0006] Lithium-sulfur secondary batteries use sulfur as the positive electrode active material and lithium metal as the negative electrode. Because their theoretical energy density is higher than that of conventional lithium-based positive electrode materials, they are suitable for use in electric vehicles, which require high capacity and high energy density.

[0007] Lithium-sulfur secondary batteries typically use liquid electrolytes for ease of handling. However, lithium polysulfide, the main cathode material in lithium-sulfur secondary batteries, can dissolve in the liquid electrolyte, leading to problems such as a shortened battery life, depletion of the liquid electrolyte, and fire hazards at high temperatures.

[0008] Accordingly, various studies are being conducted to improve the structure and materials of all-solid-state lithium-sulfur batteries to increase the utilization rate of sulfur, which is the positive electrode active material, while using a solid electrolyte, and to prevent side reactions and improve characteristics such as electrochemical performance and lifespan.

[0009] Prior patent: Korean Patent No. 10-1367787 (Published: August 29, 2012)

[0010] The technical problem to be solved by the present application is to provide a positive electrode for an all-solid-state lithium-sulfur battery with improved electrochemical properties, an all-solid-state lithium-sulfur battery including the positive electrode, and a method for manufacturing the same.

[0011] Another technical problem that the present application seeks to solve is to provide a positive electrode for an all-solid-state lithium-sulfur battery having improved structural stability and thus improved capacity and cycle characteristics by using novel materials and methods in the process of manufacturing the positive electrode, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same.

[0012] The technical problems that this application seeks to solve are not limited to those described above.

[0013] The present invention, which solves the above technical problem, provides a positive electrode for an all-solid-state lithium-sulfur battery, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same.

[0014] In one embodiment, a method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery is provided, comprising: a step of manufacturing a carrier including conductive carbon having a transition metal sulfur compound coated on the surface; a step of mixing the carrier with a sulfur raw material and heating the mixture to manufacture a sulfur complex; and a step of mixing the sulfur complex with a sulfide-based solid electrolyte to manufacture a mixture, and a step of wet-mixing the mixture using a polar solvent having a first polarity index to manufacture a powder; wherein the first polarity index is 3 to 5.

[0015] In one embodiment, the sulfur complex and the sulfide-based solid electrolyte may be provided in a weight ratio of 60:8 to 40, and the mixture and the polar solvent may be provided in a weight ratio of 1:3 to 5.

[0016] In one embodiment, after the step of wet mixing to prepare a powder, a step of dry mixing by adding a sulfide-based solid electrolyte to the powder may be further included.

[0017] In one embodiment, the step of wet mixing to prepare a powder may include mixing the sulfur complex and the sulfide-based solid electrolyte at room temperature to prepare a mixture, mixing the mixture with the polar solvent to prepare a suspension, and stirring the mixture at room temperature for 10 minutes to 1 hour to evaporate the solvent of the suspension to prepare a powder.

[0018] In one embodiment, the dry mixing step may further include mixing the sulfide-based solid electrolyte so that the content of the powder and the total sulfide-based solid electrolyte is 72:20 to 50, ball milling at 200 rpm to 1200 rpm for 3 to 15 hours at a temperature range of 5°C to 20°C, and the total sulfide-based solid electrolyte may be the total sum of the content of the sulfide-based solid electrolyte used in the production of the powder and the content of the sulfide-based solid electrolyte added in the dry mixing step.

[0019] In one embodiment, the step of preparing the carrier may include: a step of providing a functional group on the surface of conductive carbon; a step of first dispersing the conductive carbon provided with the functional group in a first solution, and a step of second dispersing the conductive carbon by adding a transition metal compound and a sulfur compound including at least one of molybdenum (Mo), iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni), vanadium (V), titanium (Ti), tin (Sn), and copper (Cu) to prepare a dispersion solution; a step of placing the dispersion solution in a reactor and performing a hydrothermal reaction to prepare a solid; and a step of vacuum-drying the solid and then heat-treating it to prepare a carrier.

[0020] In one embodiment, the conductive carbon is at least one of carbon nanotubes (CNTs), carbon nanofibers, carbon nanorods, graphene, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, natural graphite, artificial graphite, and vapor-grown carbon fiber (VGCF), and the functional group is at least one of a hydroxyl group and a carboxyl group, and the first solution may include at least one of distilled water, ethylene glycol, ethanol, dimethylformamide (DMF), and glycerol.

[0021] In one embodiment, the transition metal compound may include at least one of ammonium molybdate (para) tetrahydrate, molybdic acetoacetonate, cobalt(III) acetylacetonate (MoO2(acac)2), molybdic acid (H2MoO4), ammonium tetrathiomolybdate, and molybdenum trioxide (MoO3), and the sulfur compound may include at least one of thiourea, L-cystine, sulfur, and thioacetamide.

[0022] In one embodiment, the conductive carbon includes CNT, and the first solution for the conductive carbon may have a weight ratio of 1:50 to 1000.

[0023] In one embodiment, the first solution comprises distilled water and ethylene glycol, and the distilled water and ethylene glycol may be in a weight ratio of 1 to 4:1.

[0024] In one embodiment, in the step of providing the functional group, the conductive carbon is immersed in an acidic solution at a temperature of 80° C. to 100° C. for 0.5 to 2 hours, cooled to 45° C. to 70° C., washed with an excess of distilled water so that the pH becomes neutral, and the obtained material is vacuum-dried at 80° C. to 110° C., wherein the acidic solution may include at least one of nitric acid, sulfuric acid, hydrochloric acid, and hydrofluoric acid.

[0025] In one embodiment, in the step of preparing the dispersion solution, the first dispersion may include ultrasonic dispersion at room temperature for 1 to 5 hours, and the second dispersion may include ultrasonic dispersion at room temperature for 10 to 50 minutes.

[0026] In one embodiment, in the step of manufacturing the solid material, the hydrothermal reaction is performed at 0.5 ℃ min -1 5 ℃ min -1 After heating to 180 ℃ to 250 ℃ at a speed of , it can be performed by maintaining for 12 to 36 hours, vacuum filtering, and then washing with distilled water or ethanol.

[0027] In the step of manufacturing the carrier, the vacuum drying is performed at 30°C to 100°C under vacuum, and the heat treatment is performed at 3°C ​​min in an inert gas atmosphere. -1 7 ℃ min -1 After heating to 600 ℃ to 800 ℃ at a speed of , it can be performed for 1 to 4 hours.

[0028] In one embodiment, the step of manufacturing the sulfur complex may include mixing the carrier and the sulfur raw material in a weight ratio of 1:0.5 to 2 and heating at a temperature range of 155°C to 170°C for 6 to 18 hours.

[0029] In one embodiment, the sulfur source material may include Li2S, S8, a sulfurized polymer, or a mixture of two or more thereof.

[0030] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X (X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It can be one selected from (0≤x≤2).

[0031] In one embodiment, a sulfur complex including a carrier and a sulfur raw material; and a sulfide-based solid electrolyte; wherein the sulfur complex and the sulfide-based solid electrolyte include an interface portion in contact with each other, and the interface portion includes sulfur (S) element included in the sulfur complex and PS4 included in the sulfide-based solid electrolyte. 3- Provided is a positive electrode for an all-solid-state lithium-sulfur battery, which comprises a polysulfido-intermediate compound (P-IC) formed by reacting with each other.

[0032] In one embodiment, the sulfur complex and the sulfide-based solid electrolyte may be provided in a weight ratio of 60:10 to 25.

[0033] In one embodiment, the carrier includes conductive carbon having a transition metal sulfur compound coated on the surface, and the carrier and the sulfur raw material may be provided in a weight ratio of 1:1.8 to 5.

[0034] In one embodiment, the ionic conductivity at 25°C is 1.0 x 10 -9 S / cm or more, and the horizontal force value, which is the adhesive strength between the sulfur complex and the sulfide-based solid electrolyte, may be 0.15 N or more.

[0035] In one embodiment, the carrier comprises a MoS2-coated CNT, and the polysulfido-intermediate compound comprises 3Li + -PS 4+n 3- (n≥0) can be included.

[0036] In one embodiment, the positive electrode for the all-solid-state lithium-sulfur battery is manufactured as a mixture by mixing the sulfur complex and the sulfide-based solid electrolyte, and the mixture is prepared as a powder by wet mixing using a polar solvent having a first polarity index, and the first polarity index may be 3 to 5.

[0037] In one embodiment, the mixture and the polar solvent may be provided in a weight ratio of 1:2 to 8.

[0038] In one embodiment, the polar solvent may be isopropyl acetate.

[0039] In one embodiment, the sulfur source material may include Li2S, S8, a sulfurized polymer, or a mixture of two or more thereof.

[0040] In one embodiment, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X (X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It can be one selected from (0≤x≤2).

[0041] In one embodiment, an all-solid-state lithium-sulfur battery is provided, comprising the positive electrode for the all-solid-state lithium-sulfur battery described above.

[0042] According to the present invention, by manufacturing an electrode by a wet process using a novel method, it is possible to provide a positive electrode for an all-solid-state lithium-sulfur battery capable of having a large area without reducing the capacity of the battery, an all-solid-state lithium-sulfur battery including the positive electrode, and a method for manufacturing the same.

[0043] In addition, according to the present invention, the present invention may include a positive electrode for an all-solid-state lithium-sulfur battery, which can improve the contact area between particles constituting an electrode layer, thereby mitigating the influence of volume change during a charge / discharge process and maximizing battery capacity, an all-solid-state lithium-sulfur battery including the same, and a method for manufacturing the same.

[0044] Figure 1 is a schematic diagram of a positive electrode for an all-solid-state lithium-sulfur battery according to one embodiment of the present invention.

[0045] Figure 2 is a flowchart showing a method for manufacturing an all-solid-state lithium sulfur battery according to one embodiment of the present invention.

[0046] Figure 3 shows the results of confirming the interface where sulfur and sulfide-based solid electrolytes come into contact with each other.

[0047] Figure 4 is a drawing showing color changes during wet mixing according to solvent.

[0048] Figure 5 shows the results of confirming the intermediate product between sulfur and sulfide-based solid electrolytes according to the mixing method and solvent.

[0049] Figure 6 shows the results of confirming the characteristics of the S8 / LPSCl mixture.

[0050] Figure 7 shows the results of confirming the characteristics of the positive electrode powder.

[0051] Figure 8 shows the results of confirming the characteristics of the positive electrode powder.

[0052] Figure 9 is a drawing comparing SEM images of the composite powder and anode cross-section of samples 1 to 3 prepared with DM and WM.

[0053] Figure 10 shows the characteristics of the host material.

[0054] Figure 11 is a schematic diagram of DM and WM.

[0055] Figure 12 shows the results of scanning Auger mapping (SAM) of the bipolar prepared with DM and WM.

[0056] Figure 13 shows the discharge and charge results of ASSLSB using positive electrodes prepared with DM and WM.

[0057] Figure 14 shows the mechanism of additional capacity development in ASSLSB using a positive electrode prepared with WM.

[0058] Figure 15 shows the TGA results of the anode prepared with DM and WM.

[0059] Figure 16 shows the results of the electrochemical performance of ASSLSB using anodes prepared with DM and WM.

[0060] Figure 17 shows the results of rate-dependent discharge characteristics of ASSLSB using positive electrodes prepared with DM and WM.

[0061] Figure 18 shows the results of cycle characteristics of ASSLSB using positive electrodes prepared with DM and WM.

[0062] Figure 19 shows the cycle characteristics of ASSLSBs using anodes prepared with WM.

[0063] Figure 20 shows the results of comparing the electrochemical characteristics of ASSLSB using a positive electrode prepared with WM according to the present embodiment.

[0064] Figure 21 shows the results of electrochemical characteristics of ASSLSB using a positive electrode prepared with WM and a lithium metal negative electrode according to the present embodiment.

[0065] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of 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.

[0066] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. In addition, in the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents.

[0067] Also, although terms such as first, second, and third have been used to describe various components in various embodiments of this specification, these components should not be limited by these terms. These terms are only used to distinguish one component from another. Thus, what is referred to as a first component in one embodiment may be referred to as a second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiments. Also, the term "and / or" has been used herein to mean including at least one of the components listed before and after.

[0068] In the specification, singular expressions include plural expressions unless the context clearly dictates otherwise. Furthermore, terms such as "comprises" or "has" are intended to specify the presence of a feature, number, step, component, or combination thereof described in the specification, but should not be construed as excluding the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0069] In addition, when describing the present invention below, 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.

[0070] Figure 1 is a schematic diagram of a positive electrode for an all-solid-state lithium-sulfur battery according to one embodiment of the present invention. Figure 2 is a flowchart illustrating a method for manufacturing an all-solid-state lithium-sulfur battery according to one embodiment of the present invention.

[0071] Referring to FIGS. 1 and 2, a method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery according to an embodiment of the present invention includes the steps of: manufacturing a carrier including conductive carbon having a transition metal sulfur compound coated on the surface; mixing the carrier with a sulfur raw material and heating the mixture to manufacture a sulfur complex (110); and mixing the sulfur complex (110) and a sulfide-based solid electrolyte (120) to manufacture a mixture, and wet-mixing the mixture using a polar solvent having a first polarity index to manufacture a powder; wherein the first polarity index is 3 to 5.

[0072] Typically, to manufacture a cathode for an all-solid-state lithium-sulfur battery, a method has been performed in which sulfur (e.g., S8) and a sulfide-based solid electrolyte are mixed dry without a solvent, or a method has been performed in which sulfur and a sulfide-based solid electrolyte are mixed using a non-polar solvent.

[0073] On the other hand, when manufacturing an all-solid-state lithium-sulfur battery positive electrode using this method, the sulfur and sulfide-based solid electrolyte in the all-solid-state lithium-sulfur battery positive electrode were not uniformly mixed, and the contact between these particles was poor, resulting in increased internal resistance. In severe cases, large voids were formed inside the all-solid-state lithium-sulfur battery positive electrode, resulting in a problem of reduced battery efficiency.

[0074] The positive electrode for an all-solid-state lithium-sulfur battery according to the present embodiment can be manufactured by using a polar solvent having a weak polarity and a first polarity, first preparing a sulfur complex (110) instead of the commonly used sulfur, and then mixing the sulfur complex (110) with a sulfide-based solid electrolyte (120). Unlike a conventional manufacturing method using a dry mixing process or a non-polar solvent, the method for manufacturing the positive electrode for an all-solid-state lithium-sulfur battery according to the present embodiment can efficiently mix the sulfur complex (110) and the sulfide-based solid electrolyte (120) with only simple mixing, and can minimize the occurrence of voids, which are empty spaces at the interface between the sulfur complex and the sulfide-based solid electrolyte.

[0075] The step of wet mixing to prepare a powder may be performed by mixing the sulfur complex (110) and the sulfide-based solid electrolyte (120) at room temperature to prepare a mixture, and mixing the mixture with the polar solvent to prepare a suspension. The suspension may be stirred at room temperature for 10 minutes to 1 hour to evaporate the solvent, thereby preparing a powder.

[0076] In the positive electrode (100) for an all-solid-state lithium-sulfur battery according to the present embodiment, when the sulfur complex (110) and the sulfide-based solid electrolyte (120) are mixed in the polar solvent, a chemical reaction may occur at the interface where they come into contact with each other. Specifically, the sulfur complex (110) and the sulfide-based solid electrolyte (120) react with each other at the surface during mixing to form an interface (130), and by forming the interface (130), the bonding force between the particles of the sulfur complex (110) and the sulfide-based solid electrolyte (120) is improved, thereby preventing the occurrence of voids in the positive electrode (100) for an all-solid-state lithium-sulfur battery. The interface (130) is formed by the sulfur of the sulfur complex and the PS4 contained in the sulfide-based solid electrolyte. 3- It may include a polysulfido-intermediate compound (P-IC) formed by reacting with each other.

[0077] The first polarity index of the polar solvent may be 3 to 5. When the first polarity index is less than 3, the interface portion (130) is not formed, and when it is more than 5, the sulfur complex (110) and the sulfide-based solid electrolyte (120) react excessively and become deformed, which is problematic. For example, when a solvent with a polarity index of 2.5, such as xylene, is used, the interface portion is not formed, and when a solvent with a polarity index of 5.8, such as acetonitrile, is used, the manufactured positive electrode has a reduced capacity when manufactured into an all-solid-state lithium-sulfur battery, which is problematic.

[0078] Specifically, the polar solvent may include isopropyl acetate.

[0079] The above sulfur complex (110) and the sulfide-based solid electrolyte (120) are mixed in the polar solvent having the first polarity to form a complex, and the complex can be compressed to manufacture an all-solid-state lithium-sulfur battery positive electrode (100). The cross-section of the manufactured all-solid-state lithium-sulfur battery positive electrode (100) can exhibit high capacity (sulfur utilization) with almost no voids observed. The voids act as resistance to reduce ion conductivity, and a higher sulfur utilization rate means a higher capacity.

[0080] In addition, the sulfide-based solid electrolyte (120) that participates in the reaction and forms an interface (130) can exhibit a capacity different from that of a simple mixture of conventional positive electrodes, and thus the positive electrode for the all-solid-state lithium-sulfur battery can exhibit a capacity higher than the theoretical capacity of sulfur.

[0081] The above sulfur complex (110) can be manufactured using a carrier and a sulfur raw material. The step of manufacturing the carrier may include: a step of providing a functional group on the surface of conductive carbon; a step of first dispersing conductive carbon provided with a functional group in a first solution, and a step of second dispersing a transition metal compound and a sulfur compound including at least one of molybdenum (Mo), iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni), vanadium (V), titanium (Ti), tin (Sn), and copper (Cu) to prepare a dispersion solution; a step of placing the dispersion solution in a reactor and performing a hydrothermal reaction to prepare a solid; and a step of vacuum-drying the solid and then heat-treating it to prepare a carrier.

[0082] The conductive carbon may be at least one of carbon nanotubes (CNTs), carbon nanofibers, carbon nanorods, graphene, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, natural graphite, artificial graphite, and vapor-generated carbon fiber (VGCF). The conductive carbon may be provided in a two-dimensional shape and may act as a passage for ions or electrons. Specifically, it may include carbon nanotubes, carbon nanofibers, carbon nanorods, and graphene.

[0083] The above conductive carbon includes a functional group on its surface, and can easily coat a transition metal sulfur compound by the functional group. The functional group may be at least one of a hydroxyl group and a carboxyl group. Specifically, the functional group may be a hydroxyl group.

[0084] In the step of providing the functional group, the conductive carbon may be immersed in an acidic solution at a temperature of 80°C to 100°C for 0.5 to 2 hours, cooled to 45°C to 70°C, washed with an excess of distilled water so that the pH becomes neutral, and the obtained material may be vacuum-dried at 80°C to 110°C. The acidic solution may include at least one of nitric acid, sulfuric acid, hydrochloric acid, and hydrofluoric acid.

[0085] The conductive carbon can be provided with functional groups on the surface without causing physical damage to the conductive carbon by impregnating it in the acidic solution at the temperature and time described above. Specifically, the acidic solution can be used by mixing a sulfuric acid solution (purity 95%) and a nitric acid solution (purity 60%) in a volume ratio of 3:1. In addition, the conductive carbon can be manufactured by supporting it in a strong acid solution in which the sulfuric acid solution and the nitric acid solution are mixed, performing acid treatment by stirring at 95°C for 1 hour, cooling the temperature to about 60°C, and then repeating washing and filtering multiple times with an excess of distilled water until the pH becomes 7. The material obtained in this way can be prepared by vacuum drying at 100°C.

[0086] The conductive carbon having a functional group can be first dispersed in the first solution. The first solution may include one or more of distilled water, ethylene glycol, ethanol, dimethylformamide (DMF), and glycerol. Specifically, the first solution may include distilled water and ethylene glycol.

[0087] The above transition metal compound may include at least one of ammonium molybdate (para) tetrahydrate, molybdic acetoacetonate, cobalt (III) acetylacetonate (MoO2(acac)2), molybdic acid (H2MoO4), ammonium tetrathiomolybdate, and molybdenum trioxide (MoO3), and the sulfur compound may include at least one of thiourea, L-cystine, sulfur, and thioacetamide. Specifically, the transition metal compound may be ammonium molybdate (para) tetrahydrate, and the sulfur compound may be thiourea.

[0088] The first solution for the conductive carbon may be 1:50 to 1000 by weight. If the first solution for the conductive carbon is prepared at a weight ratio of less than 50, the conductive carbon may not be uniformly dispersed in the first solution, and if the weight ratio exceeds 1000, the distance between the transition metal compound and sulfur compound added to the first solution and the conductive carbon may be too far, resulting in reduced reactivity.

[0089] Specifically, the first solution includes distilled water and ethylene glycol, and the distilled water and ethylene glycol may have a weight ratio of 1 to 4:1.

[0090] The ethylene glycol increases the dispersibility of the transition metal compound and sulfur compound added to the first solution, can control the size and shape of nanoparticles composed of the transition metal sulfur compound, and has a high boiling point, so it can affect temperature stabilization in, for example, MoS2 hydrothermal synthesis, which is only possible at high temperatures. The distilled water can supplement the ethylene glycol to control the viscosity of the ethylene glycol and can improve reactivity by ensuring that the substance added to the first solution is uniformly dispersed.

[0091] With respect to the above ethylene glycol 1 weight ratio, if the distilled water is less than 1 weight ratio, the dispersibility is high, but the growth rate of the transition metal sulfur compound formed on the surface of the conductive carbon is fast, so the particle size is small and the coating is thick, which is problematic. If the distilled water is more than 4 weight ratio, it is difficult to uniformly disperse the conductive carbon, and the particles of the transition metal sulfur compound, such as MoS2, formed on the surface of the conductive carbon are large and have a slow growth rate, so they may be unevenly coated on the surface of the conductive carbon.

[0092] In the step of preparing the above dispersion solution, the first dispersion may be ultrasonically dispersed at room temperature for 1 to 5 hours, and the second dispersion may be ultrasonically dispersed at room temperature for 10 to 50 minutes. In the step of preparing the above dispersion solution, the first dispersion may be performed so that the conductive carbon added to the first solution is uniformly dispersed. Subsequently, in the second dispersion, the transition metal compound and the sulfur compound in the dispersion solution may be completely dissolved so that the reaction with the conductive carbon may be efficiently performed. Specifically, the first dispersion may be performed for 1 to 4 hours, or for 1 to 3 hours, or for 1.5 to 3 hours, and the second dispersion may be performed for 10 to 40 minutes, or for 20 to 40 minutes.

[0093] In the step of manufacturing the above solid material, the hydrothermal reaction is carried out at 0.5 ℃ min-1 5 ℃ min -1 The step of preparing the solid may include heating to 180° C. to 250° C. at a rate of 12 to 36 hours, maintaining the temperature for 12 to 36 hours, vacuum filtering, and then washing with distilled water or ethanol. The step of preparing the solid may include preparing the conductive carbon in a form in which the transition metal sulfur compound is coated on the outer surface of the conductive carbon through a hydrothermal reaction between the transition metal compound and the sulfur compound, which are raw materials dissolved in the liquid form in the dispersion solution.

[0094] In the step of manufacturing the carrier, the vacuum drying is performed at 30°C to 100°C under vacuum, and the heat treatment is performed at 3°C ​​min in an inert gas atmosphere. -1 7 ℃ min -1 After heating to 600 ℃ to 800 ℃ at a speed of , it can be performed for 1 to 4 hours. For example, the carrier may be in the form of a coating layer of MoS2 on the outer surface of the conductive carbon. By drying in the above-mentioned temperature range during vacuum drying, the solvent remaining after the reaction can be effectively removed.

[0095] The above heat treatment can improve the crystal structure stability and crystallinity of MoS2 formed on the outer surface of the conductive carbon and remove impurities. In addition, the heat treatment can improve charge transfer by reducing defect sites of MoS2. When the heat treatment is performed at less than 600°C, the crystal structure of MoS2 due to the heat treatment is not sufficiently improved, resulting in a decrease in crystallinity and an increased possibility of defects or impurities existing inside MoS2. On the other hand, the heat treatment at more than 800°C can cause instability of the crystal structure of MoS2 and promote the creation of defects or impurities.

[0096] If the heat treatment time is less than 1 hour, sufficient heat treatment is not performed, resulting in insufficient crystallization, which reduces the crystallinity of the MoS2 crystal structure and increases the possibility of defects or impurities within the MoS2. Furthermore, if the heat treatment time exceeds 4 hours, the structure and properties of the material may be altered, so the heat treatment must be performed at an appropriate heat treatment time and temperature.

[0097] The step of manufacturing the above sulfur complex may include mixing the carrier and the sulfur raw material in a weight ratio of 1:0.5 to 2 and heating at a temperature range of 155°C to 170°C for 6 to 18 hours.

[0098] The sulfur raw material can be mixed in a weight ratio of 0.5 to 2 for the weight ratio of the above carrier. If the sulfur raw material is less than 0.5, the energy density of the positive electrode is reduced, which is problematic. If the weight ratio exceeds 2, the sulfur raw material is not uniformly distributed within the carrier, which is problematic.

[0099] After mixing the above carrier and sulfur raw material, heating can be performed. However, if the temperature during heating is lower than 155°C, the sulfur raw material does not melt and is not evenly impregnated into the carrier, which is a problem. If it exceeds 180°C, the sulfur raw material quickly vaporizes and the properties of the carrier deteriorate, which is a problem. In addition, by performing the heat treatment within the temperature range described above, the heat treatment can be performed efficiently and uniformly.

[0100] The above sulfur source material may include Li2S, S8, a sulfurized polymer, or a mixture of two or more thereof.

[0101] The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X(X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be one selected from (0≤x≤2). Specifically, the sulfide-based solid electrolyte may be at least one of Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0102] The above sulfur complex (110) and the sulfide-based solid electrolyte (120) may be provided in a weight ratio of 60:10 to 25. When the sulfur complex (110) is included in a weight ratio of less than 10, the interface portion (130) is not sufficiently formed or is formed unevenly, which is problematic, and when the weight ratio exceeds 25, the sulfide-based solid electrolyte (120) excessively participates in the reaction, which hinders ion conduction of the positive electrode (100) for a lithium-sulfur battery, which is problematic.

[0103] The above mixture and the polar solvent may be prepared in a weight ratio of 1:2 to 8. The mixture may be prepared in the form of a solid powder by mixing a sulfur complex (110) and a sulfide-based solid electrolyte (120). The mixture may be dispersed by the polar solvent. By mixing the mixture and the polar solvent in the above-described range, the mixture may be uniformly mixed, and the sulfur complex (110) and the sulfide-based solid electrolyte (120) may be effectively interacted with each other by the first polarity of the polar solvent.

[0104] Alternatively, the method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery according to the present embodiment may further include, after the step of manufacturing a powder by wet mixing, a step of adding a sulfide-based solid electrolyte to the powder and dry mixing it.

[0105] The above dry mixing step may include adding more of the sulfide-based solid electrolyte so that the content of the powder and the entire sulfide-based solid electrolyte becomes 72:20 to 50, mixing, and ball milling at 200 rpm to 1200 rpm for 3 to 15 hours in a temperature range of 5°C to 20°C. The above total sulfide-based solid electrolyte means the total sum of the content of the sulfide-based solid electrolyte used in the production of the powder and the content of the sulfide-based solid electrolyte added in the dry mixing step. In the above weight ratio, if the total sulfide-based solid electrolyte is less than 20 weight ratio with respect to the 72 weight ratio of the powder, the ion conductivity in the positive electrode composite decreases, resulting in a deterioration in performance, and if the weight ratio exceeds 50 weight ratio, the ratio of the sulfur compound relatively decreases, resulting in a problem of a decrease in the energy density of the electrode.

[0106] If the ball milling time is less than 3 hours, the powder and the sulfide-based solid electrolyte may not be uniformly mixed, which is problematic. If it exceeds 15 hours, the sulfide-based solid electrolyte may be deteriorated by the mechanical heat generated during ball milling. In addition, it is preferable to perform ball milling with air cooling to prevent the properties of the material from being deteriorated by frictional heat generated during the ball milling process.

[0107] According to another aspect of the present invention, the present invention provides a cathode for an all-solid-state lithium-sulfur battery, comprising: a sulfur complex including a carrier and a sulfur raw material; and a sulfide-based solid electrolyte; wherein the sulfur complex and the sulfide-based solid electrolyte include an interface portion in contact with each other.

[0108] The above interface portion includes the sulfur (S) element included in the above sulfur complex and PS4 included in the above sulfide-based solid electrolyte. 3- It may include a polysulfido-intermediate compound (P-IC) formed by reacting with each other.

[0109] The above-mentioned positive electrode for the all-solid-state lithium-sulfur battery has an ionic conductivity of 1.0 x 10 at 25 ℃. -9 It can exhibit very high ionic conductivity of S / cm or more. In addition, the horizontal force value, which is the adhesive strength between the sulfur complex and the sulfide-based solid electrolyte in the positive electrode for the all-solid-state lithium-sulfur battery, is 0.15 N or more (SAICAS analysis data). Therefore, when an all-solid-state battery is manufactured using the positive electrode for the all-solid-state lithium-sulfur battery according to the present embodiment, the mechanical strength and life characteristics can be improved due to the high adhesive strength between the all-solid-state electrolyte.

[0110] For example, the sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X(X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It can be one selected from (0≤x≤2).

[0111] The above-mentioned positive electrode for an all-solid-state lithium-sulfur battery may include a sulfur complex and a sulfide-based solid electrolyte. The sulfur complex is manufactured by providing a sulfur raw material to a carrier, and specifically, the carrier may include a CNT coated with MoS2.

[0112] The above-mentioned positive electrode for the all-solid-state lithium-sulfur battery is manufactured as a mixture by mixing the sulfur complex and the sulfide-based solid electrolyte, and the mixture may be prepared as a powder by wet mixing using a polar solvent having a first polarity index. The first polarity index may be 3 to 5, and specifically, the polar solvent may be isopropyl acetate.

[0113] After wet mixing the above sulfur complex and the sulfide-based solid electrolyte using a polar solvent, an interface is formed between the sulfur complex and the sulfide-based solid electrolyte through a reaction, and the interface may include a polysulfido-intermediate compound. In addition, the polysulfido-intermediate compound may include 3Li. + -PS 4+n 3- (n≥0) can be included.

[0114] According to another aspect of the present invention, the present invention includes an all-solid-state lithium-sulfur battery comprising the positive electrode for the all-solid-state lithium-sulfur battery described above.

[0115] The above-mentioned positive electrode for an all-solid-state lithium-sulfur battery may be prepared as a positive electrode layer by mixing it with a binder and a conductive agent. Specifically, the positive electrode layer may be manufactured by mixing the above-mentioned positive electrode for an all-solid-state lithium-sulfur battery, a binder, and a conductive agent in a dispersion medium and then drying the dispersion medium.

[0116] The above dispersion medium may be at least one of a mixture containing octyl acetate and octanol, a mixture of nonyl acetate and nonyl alcohol, a mixture of heptyl acetate and heptanol, heptane, dibutyl ether, tributyl amine, triethyl amine, toluene, xylene, tetrahydrofuran, and anisole.

[0117] The above binder may be at least one of polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoro propylene copolymer, polyacrylonitrile, polymethyl methacrylate, nitrile butadiene rubber (NBR), polystyrene, and poly(ethylene oxide) (PEO).

[0118] The above-mentioned conductive material may be at least one of graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, carbon nanofiber, and carbon nanotube.

[0119] In addition, the above-mentioned positive electrode layer may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the positive electrode, binder, and conductive agent for the above-mentioned all-solid-state lithium-sulfur battery.

[0120] Hereinafter, examples and comparative examples of the present invention are described. However, the following examples are only preferred embodiments of the present invention and the scope of the present invention is not limited by the following examples.

[0121] 1. Prepare the ingredients

[0122] MoS2@CNT host was manufactured using the following materials.

[0123] Multi-walled CNTs (97%; TCI), ethylene glycol (99.5%; JUNSEI CHEMICAL), thiourea (NH2CSNH2, 98%; JUNSEI), ammonium molybdate (para) tetrahydrate ((NH4)6Mo7O 24·4H2O, 99.98% trace metals basis; Alfa Aesar)

[0124] The following materials were used to prepare the S cathode and ASSLSB.

[0125] Sulfur (99.98% trace metals basis; Sigma-Aldrich), Li6PS5Cl (LPSCl, 3 μm for cathode fabrication, 8 μm for solid electrolyte layer; CIS Co., Ltd.), isopropyl acetate (99.6%; Sigma-Aldrich), lithium powder (Livent), indium powder (99.99%; Sigma-Aldrich)

[0126] 2. Synthesis of S-impregnated host (Host / S)

[0127] The CNT surface was functionalized through acid treatment to form hydrophilic functional groups on the CNT surface. CNTs with hydrophilic functional groups formed on their surface facilitated the coating of MoS2.

[0128] Hydroxylated CNTs (100 mg) were dispersed in a solution consisting of 53 ml of distilled water and 13 ml of ethylene glycol, and then ultrasonicated for 2 hours. Afterwards, 0.33 mmol (NH4)6Mo7O was added to the solution. 24 ·4H2O and 9.33 mmol thiourea were added, and the precursor was completely dissolved by ultrasonic treatment for 30 minutes to prepare a dispersion solution. The obtained dispersion solution was placed in a 100 ml hydrothermal synthesis vessel (Teflon-lined stainless steel autoclave) and heated at 200°C for 2°C min. -1After heating at a rate of , it was maintained at 200 ℃ for 24 hours. After that, the solid was selected through vacuum filtration and washed with distilled water and ethanol. The solid was dried in a glass oven at 60 ℃ under vacuum overnight. After the material was completely dried, it was heated in a furnace at 5 ℃ min. -1 MoS2@CNT (Host), a MoS2-coated CNT, was prepared by heat treatment at 700 ℃ for 2 hours in an argon atmosphere at a heating rate of .

[0129] The host / S composite was prepared using a conventional melt-diffusion method. Sulfur and the host, MoS2@CNT, were uniformly mixed at a weight ratio of 1:2. The resulting mixture was heated at 155°C for 12 h using a heating mantle to uniformly coat the host surface with sulfur.

[0130] 3. Preparation of S cathode materials

[0131] The S cathode composite powder prepared by dry mixing (DM) was manufactured by mechanical milling.

[0132] Host / S and LPSCl were gently mixed in a weight ratio of 60:40 using an Agate mortar. The mixture was ball-milled in an 80 ml ZrO2 pot at 15°C with air cooling for 12 h using a planetary ball mill (Pulverisette 7, Fritsch GmbH) at 400 rpm.

[0133] The S cathode composite powder prepared by wet mixing (WM) was prepared by combining wet mixing and mechanical milling in a weakly polar solvent.

[0134] Host / S and LPSCl were gently mixed at a weight ratio of 60:12 using an Agate mortar. The prepared mixture and the solvent (isopropyl acetate) were mixed at a weight ratio of 1:3.9 (mixture:solvent) and stirred for 10 minutes to prepare a suspension. The prepared suspension was mixed for 15 minutes using an Agate mortar until the solvent evaporated, and the resulting powder was dried under vacuum overnight in a glass oven at room temperature. The dry powder with added LPSCl (weight ratio 72:28) was ball milled using the same method used for dry mixing (DM), and all mixing processes except ball milling and vacuum drying were performed in an argon-atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm). In other samples, wet mixing was used, but the type of solvent was different, and the remaining methods were the same to prepare S cathode composite powders, and the samples are shown in Table 1 below.

[0135] Distinction Mixing Method Solvent Sample 1 Dry Mix (DM) None Sample 2 Wet Mix (WM) Isopropyl Acetate Sample 3 Wet Mix (WM) Xylene Sample 4 Wet Mix (WM) Acetonitrile

[0136] 4. Manufacturing of ASSLSBs

[0137] ASSLSBs (All-Solid-State Lithium Sulfur Batteries) use two titanium rods with an inner diameter of 10 mm as current collectors and are assembled using a polyaryl ether ether ketone (PEEK) mold inside a SUS sleeve.

[0138] LPSCl powder (100 mg) was pressurized at 130 MPa for 10 s to form an electrolyte layer, and then the cathode composite powder was spread over the electrolyte layer and pressurized at 400 MPa for 3 minutes. Next, the cathode powder was added to the opposite side, and the entire assembly was compressed at 400 MPa for 1 minute to complete the cell assembly. Finally, the cell was fixed with a SUS framework, and when the external pressure was removed, the pressure inside the cell was confirmed to be ~240 MPa.

[0139] To manufacture the cathode powder, first, Li and In powders are mixed with Li 0.5 The mixture was ball milled at 2000 rpm to obtain the composition of In. The prepared mixture was mixed with LPSCl powder at a weight ratio of 8:2 and mixed at 2000 rpm. All processes were performed in an argon-filled glove box.

[0140] 5. Electrochemical analysis

[0141] Galvanostatic cycling tests were performed using battery test equipment (CTS LAB; BaSyTec) in constant current (CC) mode at 30°C over a voltage range of 0.8–2.5 V (vs. Li / In).

[0142] S loading level is 2 mg cm -2 For ASSLSB, the first two cycles were 0.33 mA cm -2 (0.1 C, 1 C = 1675 mA g -1 sulfur ) current density, the subsequent cycle was 1.66 mA cm -2 (0.5 C) was performed.

[0143] S loading level is 4 mg cm -2 For ASSLSB, the first two cycles were 0.33 mA cm -2 Current density of (0.05 C), subsequent cycles 1.00 mA cm -2 was performed in .

[0144] Electrochemical impedance spectroscopy (EIS) analysis was performed using a VMP3 instrument (SP-300, BioLogic). EIS data for the S anode were measured with an amplitude of 10 mV in the range of 7 MHz to 1 mHz in an electron-blocking cell configuration. Constant voltage (CV) measurements were performed using the VMP3 instrument at 30°C with a sensitivity of 0.05 mVs. -1 The measurements were performed in the voltage range of 0.8–2.5 V (vs. Li / In) at a scan rate of .

[0145] S loading level is 2 mg cm -2 The charge and discharge rate characteristics of ASSLSB were compared by discharging or charging at current densities ranging from 0.1 C to 2.0 C, but fixing the current density to 0.2 C.

[0146] For GITT (galvanostatic interpective titration technique) measurements, the S loading level during the first cycle was 4 mg cm -2 ASSLSB of 0.33 mA cm -2 After operating for 12 minutes at a current density of , a rest period of 20 minutes was maintained.

[0147] 6. Characteristic Analysis

[0148] Raman spectroscopy mapping was analyzed by scanning 10 times with an ionoelectric Raman system (DXR3xi; Thermo Fisher Scientific) using a 532 nm laser under the conditions of laser power 0.5 mW and exposure time 20 Hz. Surface and interface measurements were performed with a cutting analysis system (SAICAS, SAICAS EN-EX; DAIPLA WINTES) after cutting the sample to a depth of 15 μm with a 1 mm diamond blade at a scanning frequency of 2.0 μm s. -1The horizontal scan was performed at a speed of 1000 s, and the shear, inclination, and relief angles were set to 45°, 20°, and 10°, respectively. The surface and cross-sectional morphology of the S anode were analyzed using a scanning electron microscope (SEM; Verios G4UC, Thermo Fisher Scientific) equipped with a vacuum holder. Cross-section polishing was performed using a cross-section polisher (CP, IB-19520CCP; JEOL) with an Ar-ion beam at 90°C equipped with a vacuum holder. Low-temperature transmission electron microscopy (TEM, NEO ARM; JEOL) analysis was performed at 170°C using a cooling holder (613; Gatan) and a temperature controller (1905; Gatan). Thermogravimetric analysis (TGA, STA 449 F3 Jupiter; METZSCH) was performed at 5°C min under a nitrogen atmosphere. -1 The heating rate was , and the gas flow rate was 50 ml min. -1 , and heated up to 900 °C. X-ray photoelectron spectroscopy (XPS) analysis was performed using a vacuum holder with a spectrometer (K-Alpha+; Thermo Fisher Scientific) equipped with a monochromatic Al-Kα radiation (1486.6 eV) source and an energy of 12 keV / 6 mA. The crystal structure of the material was determined using an X-ray diffractometer (Empyrean, PAN Analytical) equipped with Cu-Kα radiation, and data were recorded in the 2θ range of 10–80 °. 7 Li MAS NMR data were measured using a 400 MHz(C) solid-state nuclear magnetic resonance spectrometer (Ascend 400WB; BRUKER) with a magnetic field of 9.4 T and a rotation speed of 14 kHz. Samples were mounted on a 4-mm rotor inside an argon-filled glove box.

[0149] 7. Evaluation Results

[0150] Figure 3 shows the results of confirming the interface where sulfur and sulfide-based solid electrolytes contact each other. In Figure 3, (a) is an interface diagram of the mixture of S8 and LPSCl according to the mixing method, (b, c) are Raman mapping and (d, e) are specific Raman spectra showing chemical bonds in the S8 / LPSCl (1:1 weight ratio) mixture prepared using DM and WM. In Figure 3, (f) is an XPS S2p spectrum of the S8 / CNT / LPSCl (1:1:2 weight ratio) mixture prepared using DM and (g) WM, and (h) is an XPS S2p spectrum of the S8 / CNT / LPSCl (1:1:2 weight ratio) mixture prepared using LPSCl. 3- This is a diagram showing the formation of a polysulfido-intermediate compound by an interfacial chemical reaction between units. Figure 4 is a diagram showing the color change during wet mixing according to the solvent. In Figure 4, digital photographs of (a) S8 in isopropyl acetate, (b) LPSCl in isopropyl acetate, (c) S8+LPSCl in xylene, and (d) S8+LPSCl in isopropyl acetate are shown, respectively. Figure 4 (e) shows the photograph of S8+LPSCl in isopropyl acetate heated at 60°C for 1 hour, showing the color change of the solution when an excessive chemical reaction occurs between S8 and LPSCl. Figure 5 shows the results of confirming the intermediate product between sulfur and sulfide-based solid electrolytes according to the mixing method and solvent. In Figure 5, the left side shows Raman mapping, and the right side shows a specific Raman spectrum showing the chemical bonding of the prepared S8 / LPSCl mixture. Figure 6 shows the results of confirming the characteristics of the S8 / LPSCl mixture. Figure 6 shows the XRD patterns of S8, LPSCl, and S8 / LPSCl mixtures manufactured using DM and WM. Figure 7 shows the results of confirming the characteristics of the cathode powder. In Figure 7, corresponding to the LPSCl and S cathode (Host / S / LPSCl) powders using DM and WM 7 Li MAS NMR spectrum was shown.

[0151] To confirm the formation of an intermediate product between S8 and LPSCl, we used Raman analysis to identify the chemical bonds in the S8 / LPSCl mixture. Two sample powders were prepared for comparative analysis. Sample 1 consisted of an S8 / LPSCl mixture (1:2 weight ratio) prepared by dry mixing (DM), and Sample 2 was prepared by wet mixing (WM) using isopropyl acetate, followed by drying overnight in a vacuum oven at room temperature (30°C) to remove the mixed solvent (Fig. 3(a)).

[0152] Referring to Fig. 4, the intermediate material in the process of performing wet mixing using isopropyl acetate appeared slightly yellow compared to after mixing with xylene, a non-polar solvent. Fig. 4 is the result of an experiment to show that an intermediate material is formed between S and LPSCl, and is the result of analyzing a composite material in which the two materials S and LPSCl were simply mixed by each method, excluding the host material.

[0153] When mixing S and LPSCl, it was confirmed that different colors appeared when mixed in xylene, a nonpolar solvent, and when mixed in isopropyl acetate, a weakly polar solvent. This result shows that some other substances were formed through the reaction between S and LPSCl when mixed in a weakly polar solvent.

[0154] Raman mapping was performed using uniformly spread sample powder sealed with polyimide tape to prevent exposure to air. The characteristic peak of sulfur, Raman shift 155 cm -1The plots of the peak intensities of the two samples (SS bond E2 symmetry) are shown in Fig. 3(b) and (c). Fig. 3(d) and (e) show the line from point A (S8) to point E (LPSCl) of the contour plot and specific Raman spectra near each point. As the line passes through the interface where S8 and LPSCl are adjacent, the peak intensity in the profile of sample 1 gradually decreases. On the other hand, the Raman spectrum of sample 2 shows a downshift (movement to a smaller value) of the peak when moving from point A to point E. This is because Li3PS 4+n It is formed by the chemical reaction of S8 and Li3PS4 in isopropyl acetate, which is polar, and Li3PS 4+n This is because the peak corresponding to the SS bond in the Raman spectrum occurred at a lower wavelength compared to that of elemental S8. In sample 2, S8 and LPSCl chemically reacted at the interface to form a polysulfido-intermediate compound (3Li + -PS 4+n 3- (n≥0)) (hereinafter referred to as P-IC) was formed. The absence of downshift in the Raman spectrum of Sample 1 indicates that S8 and LPSCl exist independently at the interface and that there is no formation of P-IC. In addition, no downshift was observed in the Raman spectrum of the S8 / LPSCl mixture (Sample 3) using xylene, a nonpolar solvent (Fig. 5).

[0155] Referring to Figure 5, in order to confirm the formation of an intermediate substance between S and LPSCl, a complex substance in which the two substances S and LPSCl were simply mixed by each method, excluding the Host substance, was analyzed.

[0156] In Fig. 5, the S (sulfur) mapping image on the left shows the distribution of S, where a higher intensity indicates a greater distribution of S, and a lower intensity indicates a greater distribution of the remaining substance, LPSCl. At this time, it can be confirmed that as one moves from position A to F, there is a gradual shift from S to LPSCl, and in the right Raman spectrum, as one moves from A to F, a downshift of the peak is confirmed for Sample 2, while no shift occurs for Sample 1 and Sample 3. Here, ~155 cm -1 The peak is a representative peak of S.

[0157] In sample 2, as it moves from position A to F (moving from position S to position LPSCl), the peak of S gradually decreases. At this time, it was confirmed that in the case of a simple mixture of S and LPSCl, only the intensity decreases without a peak shift, whereas in the case of sample 2, a peak shift occurs with a decrease in intensity. This means that an intermediate substance exists between S and LPSCl.

[0158] The S 2p X-ray photoelectron spectroscopy (XPS) analysis profiles of Sample 1 and Sample 2 are shown in Fig. 3 (f) to (g). In order to improve the interfacial chemical reaction between S8 and LPSCl and to clearly observe the change in chemical bonding in preparing the S8 / LPSCl mixture of Sample 1 and Sample 2, S8 was pre-impregnated onto the surface of carbon nanotubes (CNTs) at a weight ratio of 1:1 before mixing to improve the dispersibility of S8.

[0159] For peak fitting, the peak energy separation and area ratio of the S 2p doublet were set to 1.21 eV and 0.5, respectively. The XPS profile of sample 1 showed PS4 3- S 2p of terminal yellow of unit and S8 3 / 2The main S 2p peaks were observed at 161.5 and 163.0 eV corresponding to the state, whereas the profile of sample 2 showed PS4 3- S 2p at 162.1 eV with peaks of unit and S8 3 / 2 A peak was observed. An additional peak at 162.1 eV (S B 0 ) is PS 4+n 3- This is due to the internal SS bonding of the unit.

[0160] Figure 3 (h) is PS 4+n 3- Reaction equation for unit formation. XRD and Li 7 Based on NMR analysis, the crystal structure and local lithium environment of wet-mixed sample 2 (Figs. 6 and 7) did not change significantly. On the other hand, the full width at half maximum (FWHM) of the characteristic peak of LPSCl slightly increased, confirming that LPSCl was partially amorphized.

[0161] Figure 8 shows the results of confirming the characteristics of the positive electrode powder. In Figure 8, (a, b) are Bright-field TEM images of the positive electrode (Host / S / LPSCl) composite powder, (c, e) are SEM images of the composite powders prepared by DM and (d, f) WM, and a cross-sectional SEM image of the positive electrode. In Figure 8, (g) is the Horizontal force-time profile measured by SAICAS analysis, which indicates the horizontal force required to peel the negative electrode and the adhesive force between the positive electrode components. Figure 8 (h) is the ionic conductivity of the S positive electrode analyzed using electron blocking symmetric cells (inset) for Nyquist impedance data. Figure 9 is a diagram comparing the SEM images of the composite powders of Samples 1 to 3 prepared by DM and WM and the cross-section of the positive electrode. Figure 10 shows the characteristics of the Host material. In Figure 10, (a, b, c) are SEM images of MoS2@CNT. Flower-shaped MoS2 was uniformly coated on the surface of CNTs (60 nm in diameter) with a thickness of 85 nm. Figure 11 is a schematic diagram of DM and WM. In Figure 11, (a) is a mixing process for manufacturing the S cathode composite using dry mixing (DM), and (b) is a mixing process for manufacturing the S cathode composite using wet mixing (WM). In step 1 of manufacturing WM, the Host / S / LPSCl mixture was immersed in isopropyl acetate at a weight ratio of 1:3.9 (mixture:solvent) and stirred. Then, the prepared suspension was mixed using an agate mortar until the solvent evaporated, and the resulting powder was vacuum-dried to completely remove the solvent. In step 2, the Host / S / LPSCl mixture was ball milled using the same method used for DM. Table 2 shows the resistance and effective ion conductivity of S anodes manufactured by dry mixing (DM) and wet mixing (WM).Figure 12 shows the results of Scanning Auger Mapping (SAM) of the anode prepared with DM and WM. In Figure 12, (a, b) are Scanning Auger Mapping (SAM) of the S anode using DM and WM, and (c, d) are schematic diagrams showing the Li-ion conduction path of the S anode using DM and WM with arrows. In black and white, the light part represents SE, and the relatively dark part represents Host / S.

[0162] Distinctive Mixing Method R SE (Ω)R CE (Ω)σ ion,eff (μS cm -1 )Sample 1DM35.21671.9810.29Sample 2WM35.64376.4411.2

[0163] (Formula) Z high-frequency = R SE

[0164] (Formula) Z low-frequency = R SE + R SE

[0165] (Formula) σ ion,eff = d CE / (R CE X A CE )

[0166] The values ​​in Table 2 were derived from EIS data using the solid electrolyte layer resistance (RSE), the ion transfer resistance (RCE) of the anode, and the effective ionic conductivity (σion,eff) (see Fig. 8), and were calculated according to the above equation. Here, d CE Wow A CE represent the thickness and area of ​​the anode, respectively.

[0167] Because sulfur is electrically insulating, a host material capable of effectively transferring electrons to sulfur is crucial for fully utilizing sulfur among cathode active materials. In this example, a sulfur-impregnated MoS2@CNT host (hereinafter referred to as Host / S) was fabricated using a MoS2-wrapped CNT (MoS2@CNT) host. Here, the CNT and the sulfur-impregnated MoS2 directly transfer electrons, eliminating contact issues between the sulfur and the conductive carbon.

[0168] The scanning electron microscope (SEM) image in Fig. 10 confirmed the structure of the MoS2@CNT host, in which MoS2 uniformly wrapped around the CNT in a flower-like shape. The microstructure of the cathode powders composed of Host / S and LPSCl prepared through dry mixing (DM) for Sample 1 and wet mixing (WM) for Sample 2 was analyzed using a transmission electron microscope (TEM) equipped with a cooling holder. The detailed mixing process is shown in Fig. 11.

[0169] The cathode powder prepared by WM did not contain a mixed solvent because it went through a drying process. When the cathode (Host / S / LPSCl) powder was prepared by DM, the flower shape of MoS2 was clearly observed because Host / S and LPSCl existed independently (Fig. 8(a)). On the other hand, in the Host / S / LPSCl powder prepared using WM, the edge lines of the MoS2 particles appeared unclear (Fig. 8(b)). This is because Host / S was closely surrounded by P-IC and LPSCl.

[0170] In the low-magnification SEM image, the surface of the cathode powder prepared using DM appeared rough and uneven, with cracks and voids (Fig. 8(c)). However, the sample prepared using WM appeared smooth with the raw materials well connected to each other (Fig. 8(d)). The cathode powder was prepared with a sulfur (S) loading of 2 mg cm -2When fabricated as a pellet-type electrode, the anode prepared using DM had a thickness of 54.3 μm and had large voids (Fig. 8(e)). On the other hand, the anode prepared using WM had a thickness of 33.1 μm, indicating a 164% reduction in anode thickness compared to the anode prepared using DM, and exhibited a dense cross-sectional structure with significantly reduced internal pores (Fig. 8(f)). Referring to Fig. 8(g), the results of analysis using the Interfacial Adhesion Analysis System (SAICAS) showed that the adhesion between the electrode components of the anode prepared using WM was significantly higher than that of the anode prepared using DM.

[0171] As shown in Fig. 9, when comparing the cathode powder and cross-section of the cathode prepared using DM (Sample 1), the cathode prepared using WM (Sample 2), and the cathode prepared using WM but using xylene (Sample 3), it was confirmed that the cathode prepared using a weakly polar solvent, Sample 2, had almost no voids inside and was compact and thin, allowing for the manufacture of a cathode. On the other hand, Sample 1, which did not use a solvent, was confirmed to have a large void, and Sample 3, which used a non-polar solvent, was confirmed to have a better performance than Sample 1 but had larger voids than Sample 2.

[0172] The Nyquist plot was confirmed using a lithium-indium-based electron blocking cell (Li-In / LPSCl / anode / LPSCl / Li-In) (Fig. 8(h)). The anode prepared using WM exhibited lower lithium ion transport resistance than the anode prepared using DM. The high-frequency impedance is determined by the resistance of the electrolyte (LPSCl) layer, and the low-frequency impedance is determined by the sum of the resistance of the electrolyte layer and the resistance of the anode. The anode prepared using WM exhibited lower ion transport resistance and higher effective ionic conductivity than the anode prepared using DM. In other words, it is believed that the contact between the anode components was improved, facilitating lithium ion transport within the electrode.

[0173] The adhesion between Host / S and LPSCl ensured that each material was uniformly dispersed without agglomeration, as confirmed by Auger electron spectroscopy mapping (SAM) (Fig. 12(a) and (b)). This adhesion enhanced the connectivity of the ion conduction paths, which could increase the ionic conductivity within the electrode (Fig. 12(c) and (d)). In addition, the significant improvement in ionic conductivity and adhesive strength obtained using xylene in WM, as in Sample 3, was not observed. This result confirmed that P-IC formed by the polar solvent played an important role.

[0174] That is, in the S anode prepared using DM, low solid-solid contact between Host / S and LPSCl was observed, whereas in the S anode prepared using WM, close and compatible high solid-solid contact was formed between S and LPSCl, which resulted in overall improvement in the compactness, mechanical strength, and ionic conductivity of the electrode.

[0175] Figure 13 shows the discharge and charge results of ASSLSB using positive electrodes prepared with DM and WM. In Figure 13, 2 mg cm -2Constant voltage (CV) curves and charge-discharge curves during galvanostatic discharge and charge using (a, c) DM and (b, d) WM using S loading ASSLSB. The constant voltage (CV) test was performed at 0.05 mV s -1 The charge-discharge cycle tests were performed in the voltage range of 0.8-2.5 V at a scan rate of 0.33 mA cm. -2 It was performed at a current density of . Figure 13(e) is a schematic of the experimental conditions for TGA analysis, and (f) is the TGA profile of the S anode before cycling and the prepared S anode recovered after two cycles. Figure 14 shows the mechanism of additional capacity development in ASSLSB using the anode prepared with WM. Figure 14 shows the reaction mechanism that provides additional charge capacity by forming SS bridges in ASSLSBs using WM. Figure 15 shows the TGA results of the anodes prepared with DM and WM. Figure 15 shows the TGA profiles of LPSCl and S8 / LPSCl mixtures at a weight ratio of 1:2.

[0176] To investigate the electrochemical actuation of ASSLSB fabricated with anode fabricated using WM, 0.05 mV s -1 Cyclic voltammetry (CV) was analyzed in the voltage range of 0.8–2.5 V (vs. Li / In) at a scan rate of . Li / In alloy and LPSCl were used as the cathode and separator, respectively, for the fabrication of ASSLSB cells. The S loading level of each cathode was 2 mg cm -2In Fig. 12, a (DM) and b (WM) represent CV curves for the first two cycles, where ASSLSB using electrodes prepared using DM and WM showed major reduction and oxidation peaks at approximately 1.1 V and 1.8 V, respectively, corresponding to S lithiation and delithiation reactions. The CV curves of the first and second cycles of ASSLSB using DM electrode overlapped, but the CV curves of ASSLSB using WM electrode showed different shapes during the cathode process.

[0177] A new peak near 1.4 V, which was not observed for ASSLSB (DM), appeared in the second cycle of CV testing for ASSLSB (WM). It was 0.33 mA cm in the voltage range of 0.8–2.5 V (vs. Li / In). -2 The voltage profiles of the first two galvanostatic charges and discharges (Fig. 13(c) and (d)) operated by ) were found to correspond to the corresponding CV curves.

[0178] The CV curve of ASSLSB (WM) showed a discharge profile with a longer discharge duration in the second discharge compared to the first discharge. The discharge capacity (2.4 mAh cm) in the first discharge of ASSLSB (WM) -2 ) is the discharge capacity (2.8 mAh cm) in the first discharge of ASSLSB (DM). -2 ) than 0.4 mAh cm -2 was low. The subsequent charging capacity (3.4 mAh cm -2 ) is provided by ASSLSB (WM), which exceeds the first discharge capacity and charge capacity of ASSLSB (DM) in the same cycle (2.7 mAh cm -2) was larger than that of the previous discharge capacity. In the first discharge process of ASSLSB (WM), the low discharge capacity was derived from the sulfur, which was partially consumed during the P-IC formation process. On the other hand, P-IC provided additional charge capacity by forming an SS bridge through the reaction shown in Fig. 14. Therefore, the charge capacity provided in the first cycle was higher than the discharge capacity provided in the same cycle. In the second cycle, ASSLSB (WM) showed a decrease in the previous charge capacity (3.4 mAh cm) due to the disassembly of the SS bridge. -2 ) comparable to 3.4 mAh cm -2 provided a discharge capacity of .

[0179] Figures 13(e) and (f) show the analytical conditions of thermogravimetric analysis (TGA) for the anode sample analysis and the TGA profiles of the S anodes prepared using DM and WM. Figure 15 shows the TGA profiles of LPSCl and the S8 / LPSCl mixture. S8 started to vaporize at approximately 200–300 °C, and a slight weight loss (< 5%) due to the decomposition of LPSCl was observed in the range of 100–600 °C. Taking this into account, the TGA data of the S anode prepared using WM was extracted after the second discharge, and a very small amount of S8 remained, indicating efficient utilization of S8. In contrast, the S anode prepared using DM contained a significant amount of remaining S8 that did not participate in the electrochemical discharge process. The TGA profile of the S anode prepared using DM showed that the vaporization of S8 was in the range of 200°C to 300°C, but the profile of the S anode prepared using WM showed that LPSCl and S8 combined through the formation of an intermediate compound, which increased the vaporization temperature of S8 to a higher 650°C, indicating that the vaporization rate of S8 was slowed down.

[0180] Figure 16 shows the electrochemical performance of ASSLSB using anodes prepared with DM and WM. In Figure 16, (a) is a schematic diagram of the Host / S and LPSCl interface characteristics in the S anode using DM and (b) WM, and (c) is a comparison of the rate-dependent charge characteristics of ASSLSB using DM, WM, and WM (Xylene). In Figure 16, (d) is the rate-dependent charge characteristic normalized to the second discharge capacity. The charge rate experiment was performed from 0.1 C to 2 C, and the discharge C-rate was fixed at 0.2 C, except for the first two cycles performed at 0.1 C. In Figure 16, (e, f) are comparisons of the second cycle capacity and the corresponding area-wise capacity of ASSLSB using DM and WM according to the S loading level. In Figure 16, the S loading level was 4 mg cm at various current densities. -2 (g) Discharge and charge curves of ASSLSB using DM and (h) WM, and (i) GITT curve and overvoltage curve (insert) of ASSLSB using DM and WM. (j) of Fig. 16 shows the voltage range of 0.8 to 2.5 V, current density of 1 mA cm -2 S loading level is 4 mg cm -2 The cycle performance of the ASSLSB prepared with DM and WM was shown. Figure 17 shows the results of the rate-dependent discharge characteristics of the ASSLSB using the positive electrodes prepared with DM and WM. In Figure 17, (a) is a comparison of the discharge rate characteristics of the ASSLSB using DM and WM, and (b) is the rate-dependent characteristics normalized by the second cycle discharge capacity. The rate-dependent characteristic test was performed from 0.1 C to 2 C, and the charge C-rate was fixed at 0.2 C except for the first two cycles at 0.1 C. Figure 18 shows the results of the cycle characteristics of the ASSLSB prepared with DM and WM. Figure 18 is the Coulombic efficiency of the cycle data shown in (j) of Figure 16, and is 1 mA cm in the voltage range of 0.8 to 2.5 V. -2The S loading level operating at a current density of 4 mg cm -2 The results obtained from ASSLSB. Figure 19 shows the cycle characteristics of ASSLSBs using the positive electrode prepared with WM. In Figure 19, the S loading is 1.5 mg cm -2 and the current density is 1.3 mA cm -2 The long-term cycling performance and Coulombic efficiency of ASSLSBs operated in the voltage range of 0.8–2.5 V at (0.5 C) were demonstrated.

[0181] Figures 16(a) and (b) show the characteristics of the S positive electrode prepared with WM in which an intermediate compound was generated between LPSCl and S8. The wettability of LPSCl was greatly increased, facilitating the utilization of S8 and minimizing the space inside the electrode. Figures 16(c) and (d) show the rate-dependent charge characteristics of the ASSLSB using the S positive electrodes prepared with WM and DM from 0.1 C to 2.0 C. Figure 17 shows the rate-dependent discharge characteristics. The ASSLSB using the S positive electrode prepared with WM showed higher capacity and higher rate-dependent characteristics than the S positive electrode prepared with DM at all charge and discharge C-rates.

[0182] As confirmed in Figure 8, the use of xylene in WM did not substantially improve the rate characteristics. This suggests that the formation of P-ICs regulates the charge and discharge processes of ASLSB, facilitating ionic charge transfer. Typically, it has been difficult to fabricate ASLSBs with high capacity due to low ionic conductivity in thick S anodes.

[0183] In this example, to demonstrate the practicality of ASSLSB with a positive electrode prepared by WM, the S loading level was 4 mg cm -2ASSLSBs were fabricated. In Fig. 16(e) and (f), the discharge capacities (second cycle) of ASLSBs including positive electrodes fabricated using different mixing methods according to the S loading level are compared.

[0184] Due to the unique properties of the S cathode manufactured by WM, ASSLSB using this cathode has a capacity of 1600 mAh g regardless of the S loading level. -2 It showed a high specific capacity of 4 mg cm and an S loading level of 4 mg cm -2 6.4 mAh cm -2 showed high areal capacity. On the other hand, ASSLSB (DM) showed low specific capacity as the S loading level increased, and the S loading level was 4 mg cm -2 3.0 mAh cm -2 showed low capacity.

[0185] Figures 16(g) and (h) show the discharge-charge profiles at different current densities. The current density was 0.33 mA cm -2 at 1.00 mA cm -2 When increased to , ASSLSB including WM and DM anodes was 0.33 mA cm -2 The current density of the ASSLSB was reduced to 79.1 and 27.8%, respectively, for the capacity. Figure 16(i) shows the discharge and charge profiles of the ASSLSB using the WM and DM high loading levels of the cathodes. The data are macroscopic Li + To investigate the diffusion properties, the galvanostatic intermittent titration technique (GITT) was used. The corresponding overvoltage curves are plotted in absolute value, calculated by subtracting the quasi-open-circuit voltage from the closed-circuit voltage.

[0186] The maximum and average overvoltage values ​​of ASSLSB with WM anode were significantly lower than those with DM anode during the charging process. This result indicates that Li + This means that the diffusion rate is improved. In the cycle test, ASSLSB using DM anode was 1.00 mA cm -2 Overall 2 mAh cm for 50 cycles at a current density of -2 The ASSLSB using WM cathode showed a low capacity of 5.1 mAh cm at the same current density. -2 It showed a high initial capacity. In addition, the ASSLSB using the WM anode maintained a coulombic efficiency of approximately 100% and exhibited stable cycle characteristics for more than 250 times (Fig. 18). In other words, it was confirmed that WM also worked effectively on the high-capacity S anode for ASSLSB. Fig. 19 shows the 2 mAh cm -2 The long-term cycling characteristics of ASSLSB with the above areal capacity were demonstrated. These high areal capacity and cycling characteristics were significantly improved results that surpassed the overall performance indicators of previously known ASSLSBs (see Table 3 below).

[0187] FIG. 20 shows the results comparing the electrochemical characteristics of ASSLSBs using a positive electrode prepared with WM according to the present embodiment. FIG. 20 (a, b) shows the results comparing SSE-based ASSLSBs with high areal capacity and improved cycle characteristics at room temperature. The specific numerical values ​​are shown in Table 3 mentioned above. FIG. 20 (c) shows the results comparing solvents with different polarity indices for WM. FIG. 20 (d) shows the results comparing the positive electrode energy density of the embodiment of the present invention with the positive electrode energy densities of other ASSB systems. The specific numerical values ​​of FIG. 20 are shown in Table 4. FIG. 21 shows the results showing the electrochemical characteristics of ASSLSBs using a positive electrode prepared with WM according to the present embodiment and a lithium metal negative electrode.

[0188] Table 3 summarizes the performance of known ASSLSBs. Table 4 presents the configuration for calculating the energy density of the ASSLSB compared to known ASSBs. In Table 4, the nominal voltages of the ASSLSB and ASSB were set to 2.0 V and 3.7 V, respectively.

[0189] No.StrategyS loading / mg cm -2 S contents / %Initial realcapacity / mAh cm -2 Initial cathode specific capacity / mAh g -1 Cyclingcurrent density / mA cm -2 Cycle numberCapacitydegradationper cycle / %Anode type1This work4206.46323.212500.144Li / In alloy1.5202.73363.51.2610000.0562S / VS2 / Li3PS45.16(S / VS2loading: 15.5)207.8301.90.12103.33Li / In alloy0.63(S / VS2loading: 1.9)200.82260.30.271000.276Li3S / CNT / Li 10 GeP2S 12 5.9255.98253.20.1201.395Li / In alloy1.3251.72330.80.212000.0624Li2S-LiI / VGCF / Li3PS4(Li2S loading: 7.64)(Li2S contents: 36.9)6.97336.60.45202Li(Li2S loading: 2.54)(Li2S contents: 36.9)2.41350.10.591000.1515Li2S / LiVS2 / Li 5.5 PS 4.5 Cl 1.5(Li2S / LiVS2loading: 6)(Li2S / LiVS2contents: 50)3.1258.31500.269Li / In alloy(Li2S / LiVS2loading: 2)(Li2S / LiVS2contents: 50)1.12750.2510000.023

[0190] No.Active material typeActive material contents / %Initialdischarge capacity / mAh g -1 Initial arealcapacity / mAh cm -2 Initial cathode specific capacity / mAh g -1 Anode typeCathodeenergydensity / Wh kg -1 1This work201710.43.42342.08Li-metal684.162NCM 90(Boron doping& coating)67.962141.64145.43Li-In alloy538.113NCM 811(Boron coating)77.29173.94.35134.41Si-C497.314NCM 622(Li2CO3 / LiNbO3coating)701360.58595.2Li4Ti5O 12 352.245SC NCA 8867.961901.46129.12Li-In alloy477.76

[0191] In an embodiment of the present invention, a wet mixing (WM) method using isopropyl acetate as a weakly polar solvent was used to manufacture an S cathode powder, and an intermediate state between S8 and LPSCl was formed. By the method for manufacturing a cathode for an all-solid-state lithium-sulfur battery according to the present embodiment, a high-density S cathode with few pores, close packing, excellent mechanical properties, and improved dispersion can be manufactured. The S cathode manufactured by wet mixing generated additional reversible capacity by P-IC, and the discharge-charge cycle characteristics were improved through bridging and cleavage of terminal sulfur.

[0192] When solvents with various polarity indices were used in the wet mixing, isopropyl acetate, which has a weak polarity of 4.2, was the most effective because it induced an interfacial reaction between S and LPSCl without severe structural collapse of LPSCl (Fig. 20(c)). On the other hand, the S cathode prepared by WM using acetonitrile (ACN) with a polarity indices of 5.8, such as Sample 4, exhibited a lower capacity than the cathode prepared by WM using nonpolar solvents that are difficult to form P-IC.

[0193] The unique S anode with ideal solid (S)-solid (LPSCl) contact has a capacity of 684 Wh kg -1 It exhibits high energy density, which is Ni-rich Li[Ni for ASSB x Co y Mn 1-(x+y) ]O2 anode material and the energy density of the conventional anode with SSE was higher than that of the anode (Fig. 20(d), Fig. 21, Table 4). The ASSLSB with the S anode according to the present embodiment exhibited a high current density (1 mA cm -2 ) with high capacity per area (5.1 mAh cm -2 ) was able to exhibit improved cycle characteristics (250 times).

[0194] Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. A step of manufacturing a carrier including conductive carbon having a transition metal sulfur compound coated on the surface; A step of mixing the carrier and the sulfur raw material and then heating to produce a sulfur complex; and A step of mixing the above sulfur complex and the sulfide-based solid electrolyte to prepare a mixture, and wet-mixing the mixture using a polar solvent having a first polarity index to prepare a powder; A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the first polarity is 3 to 5.

2. In paragraph 1, The above sulfur complex and the above sulfide-based solid electrolyte are provided in a weight ratio of 60:8 to 40, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the above mixture and the polar solvent are prepared in a weight ratio of 1:3 to 5.

3. In paragraph 1, After the above wet mixing step of manufacturing into powder, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, further comprising a step of adding a sulfide-based solid electrolyte to the above powder and dry mixing.

4. In paragraph 3, The step of manufacturing the powder by wet mixing is as follows: A mixture is prepared by mixing the above sulfur complex and the above sulfide-based solid electrolyte at room temperature, The above mixture is mixed with the above polar solvent to prepare a suspension, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, comprising manufacturing a powder by stirring at room temperature for 10 minutes to 1 hour so that the solvent of the suspension evaporates.

5. In paragraph 4, The above dry mixing step is, Add the sulfide-based solid electrolyte and mix so that the content of the powder and the entire sulfide-based solid electrolyte is 72:20 to 50, Ball milling at 200 rpm to 1200 rpm for 3 to 15 hours in a temperature range of 5 ℃ to 20 ℃, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the total sulfide-based solid electrolyte is the sum of the content of the sulfide-based solid electrolyte used in the manufacture of the powder and the content of the sulfide-based solid electrolyte added in the dry mixing step.

6. In paragraph 1, The step of manufacturing the above carrier is: A step of providing a functional group on the surface of a conductive carbon; A step of preparing a dispersion solution by first dispersing conductive carbon equipped with a functional group in a first solution, and then secondarily dispersing a transition metal compound and a sulfur compound including at least one of molybdenum (Mo), iron (Fe), cobalt (Co), manganese (Mn), nickel (Ni), vanadium (V), titanium (Ti), tin (Sn), and copper (Cu); A step of placing the above dispersion solution into a reactor and performing a hydrothermal reaction to produce a solid; and A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, comprising the step of manufacturing a carrier by vacuum-drying the above-mentioned solid material and then heat-treating it.

7. In paragraph 6, The above conductive carbon is at least one of carbon nanotubes (CNT), carbon nanofibers, carbon nanorods, graphene, carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, natural graphite, artificial graphite, and vapor-generated carbon fiber (VGCF). The functional group is at least one of a hydroxyl group and a carboxyl group, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the first solution comprises at least one of distilled water, ethylene glycol, ethanol, dimethylformamide (DMF), and glycerol.

8. In paragraph 6, The above transition metal compound is at least one of ammonium molybdate (para) tetrahydrate, molybdic acetoacetonate, cobalt (III) acetylacetonate (MoO2(acac)2), molybdic acid (H2MoO4), ammonium tetrathiomolybdate, and molybdenum trioxide (MoO3). A method for manufacturing a positive electrode for an all-solid-state lithium sulfur battery, wherein the sulfur compound comprises at least one of thiourea, L-cystine, sulfur, and thioacetamide.

9. In paragraph 6, The above-mentioned conductive carbon includes CNT, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the first solution for the above-mentioned conductive carbon is in a weight ratio of 1:50 to 1000.

10. In paragraph 6, The first solution contains distilled water and ethylene glycol, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the distilled water and ethylene glycol are in a weight ratio of 1 to 4:

1.

11. In paragraph 6, In the step of providing the above functional group, The above-mentioned conductive carbon is immersed in an acidic solution at a temperature of 80°C to 100°C for 0.5 to 2 hours, After cooling to 45℃ to 70℃, wash with an excess of distilled water until the pH becomes neutral. Including vacuum drying the obtained material at 80 ℃ to 110 ℃, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the acid solution comprises at least one of nitric acid, sulfuric acid, hydrochloric acid, and hydrofluoric acid.

12. In paragraph 6, In the step of preparing the above dispersion solution, The above primary dispersion includes ultrasonic dispersion at room temperature for 1 to 5 hours, The above secondary dispersion includes ultrasonic dispersion at room temperature for 10 to 50 minutes, In the step of manufacturing the above solid material, The above hydrothermal reaction was carried out at 0.5 ℃ min -1 5 ℃ min -1 After heating to 180 ℃ to 250 ℃ at a speed of , it is performed by maintaining for 12 to 36 hours, After vacuum filtration, washing with distilled water or ethanol is included. In the step of manufacturing the above carrier, The above vacuum drying is performed at 30°C to 100°C under vacuum, The above heat treatment was performed at 3 ℃ min in an inert gas atmosphere. -1 7 ℃ min -1 A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, comprising heating to 600°C to 800°C at a rate of 1 to 4 hours.

13. In paragraph 1, The step of manufacturing the above sulfur complex is: The above carrier and the above sulfur raw material are mixed in a weight ratio of 1:0.5 to 2, A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, comprising heating at a temperature range of 155°C to 170°C for 6 to 18 hours.

14. In paragraph 1, The above sulfur raw material includes Li2S, S8, a sulfurized polymer, or a mixture of two or more thereof, The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X (X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x A method for manufacturing a positive electrode for an all-solid-state lithium-sulfur battery, wherein the positive electrode is one selected from (0≤x≤2).

15. A sulfur complex comprising a carrier and a sulfur raw material; and Containing a sulfide-based solid electrolyte; The above sulfur complex and the above sulfide-based solid electrolyte include an interface portion in contact with each other, The above interface portion includes the sulfur (S) element included in the above sulfur complex and PS4 included in the above sulfide-based solid electrolyte. 3- A cathode for an all-solid-state lithium-sulfur battery comprising a polysulfido-intermediate compound (P-IC) formed by reacting with each other.

16. In paragraph 15, A positive electrode for an all-solid-state lithium-sulfur battery, wherein the above sulfur complex and the above sulfide-based solid electrolyte are provided in a weight ratio of 60:10 to 25.

17. In paragraph 15, The carrier comprises conductive carbon having a transition metal sulfur compound coated on its surface, A positive electrode for an all-solid-state lithium sulfur battery comprising the above-mentioned carrier and the above-mentioned sulfur raw material in a weight ratio of 1:1.8 to 5.

18. In paragraph 15, At 25 ℃, the ionic conductivity is 1.0 x 10 -9 S / cm or more, A positive electrode for an all-solid-state lithium-sulfur battery, wherein the horizontal force, which is the adhesive strength between the sulfur complex and the sulfide-based solid electrolyte, is 0.15 N or more.

19. In paragraph 15, The carrier comprises CNT coated with MoS2, The above polysulfido-intermediate compound is 3Li + -PS 4+n 3- A cathode for an all-solid-state lithium-sulfur battery comprising (n≥0).

20. In paragraph 15, The positive electrode for the above-mentioned all-solid-state lithium-sulfur battery is manufactured as a mixture by mixing the sulfur complex and the sulfide-based solid electrolyte, and the mixture is prepared as a powder by wet mixing using a polar solvent having a first polarity index. A positive electrode for an all-solid-state lithium-sulfur battery, wherein the first polarity is 3 to 5.

21. In paragraph 20, A positive electrode for an all-solid-state lithium-sulfur battery, wherein the above mixture and the polar solvent are provided in a weight ratio of 1:2 to 8.

22. In paragraph 20, A positive electrode for an all-solid-state lithium-sulfur battery, wherein the polar solvent is isopropyl acetate.

23. In paragraph 15, The above sulfur raw material is a cathode for an all-solid-state lithium sulfur battery comprising Li2S, S8, a sulfurized polymer, or a mixture of two or more thereof.

24. In paragraph 15, The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-Li X (X is a halogen element) Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x A cathode for an all-solid-state lithium-sulfur battery, wherein the cathode is one selected from (0≤x≤2).

25. An all-solid-state lithium-sulfur battery comprising a positive electrode for an all-solid-state lithium-sulfur battery according to any one of claims 15 to 24.

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