The present invention relates to a method for preparing a phase-separated lead telluride-lead sulfide nanopowder using solution synthesis and a phase-separated lead telluride-lead sulfide nanopowder prepared by the method. The method includes: (a) mixing tellurium and a first solvent, followed by ultrasonic irradiation to prepare a tellurium precursor solution; (b) mixing an organosulfur compound and a second solvent, followed by ultrasonic irradiation to prepare a sulfur precursor solution; (c) mixing lead oxide, a third solvent, and a fourth solvent and heating the mixture to prepare a lead precursor solution; (d) adding the tellurium precursor solution to the lead precursor solution and allowing the mixture to react; (e) adding the sulfur precursor solution to the reaction mixture of step (d) and allowing the resulting mixture to react; and (f) cooling the reaction mixture of step (e) to room temperature to prepare a phase-separated lead telluride-lead sulfide nanopowder.

An object of the present invention is to provide a novel sulfur-based positive electrode active material for a lithium-ion secondary battery which is excellent in cyclability and can largely improve a charging and discharging capacity, a positive electrode comprising the positive electrode active material and a lithium-ion secondary battery made using the positive electrode. The sulfur-based positive electrode active material is obtainable by subjecting a starting material comprising a polymer, sulfur and an organometallic compound dispersed in a form of fine particles to heat-treatment under a non-oxidizing atmosphere, wherein the particles of metallic sulfide resulting from sulfurization of the organometallic compound are dispersed in the heat-treated material, and particle size of the metallic sulfide particles is not less than 10 nm and less than 100 nm.

An object of the present invention is to provide a novel sulfur-based positive electrode active material for a lithium-ion secondary battery which is excellent in cyclability and can largely improve a charging and discharging capacity, a positive electrode comprising the positive electrode active material and a lithium-ion secondary battery made using the positive electrode. The sulfur-based positive electrode active material is obtainable by subjecting a starting material comprising a polymer, sulfur and an organometallic compound dispersed in a form of fine particles to heat-treatment under a non-oxidizing atmosphere, wherein the particles of metallic sulfide resulting from sulfurization of the organometallic compound are dispersed in the heat-treated material, and particle size of the metallic sulfide particles is not less than 10 nm and less than 100 nm.

The present invention relates to a method for preparing a two-dimensional transition metal dichalcogenide and, more particularly, to a method for preparing a highly uniform two-dimensional transition metal dichalcogenide thin film. More specifically, the present invention is directed to a preparation method for a highly uniform two-dimensional transition metal dichalcogenide thin film at low temperature of 500 C. or below.

The present invention relates to a method for preparing a two-dimensional transition metal dichalcogenide and, more particularly, to a method for preparing a highly uniform two-dimensional transition metal dichalcogenide thin film. More specifically, the present invention is directed to a preparation method for a highly uniform two-dimensional transition metal dichalcogenide thin film at low temperature of 500 C. or below.

A method that uses a pressurized reactive medium composed of inert solvents such as pressurized liquid or supercritical fluid carbon dioxide (C02), and sulfur hexafluoride (SF6) and reactive dissolved species ozone (03) and/or boron trifluoride (BF3) and general boron trihalogenides (BX3) to react with two-dimensional (2D) layered materials and thereby synthesize covalently oxygen and/or BX3 functionalized exfoliated 2D layered materials. When 2D layered materials are dispersed in these reactive liquids or fluids by ultrasound sonication or high shear mixing, a simultaneous covalent functionalization and exfoliation of the 2D layered materials happens. Following attainment of the required extent of functionalization and exfoliation, the unreacted 03, BX3, SF6 and C02 can be easily removed as gases by decompression leaving behind the solid phase, thereby leading to efficient and economical production of functionalized and exfoliated 2D layered materials.

A method that uses a pressurized reactive medium composed of inert solvents such as pressurized liquid or supercritical fluid carbon dioxide (C02), and sulfur hexafluoride (SF6) and reactive dissolved species ozone (03) and/or boron trifluoride (BF3) and general boron trihalogenides (BX3) to react with two-dimensional (2D) layered materials and thereby synthesize covalently oxygen and/or BX3 functionalized exfoliated 2D layered materials. When 2D layered materials are dispersed in these reactive liquids or fluids by ultrasound sonication or high shear mixing, a simultaneous covalent functionalization and exfoliation of the 2D layered materials happens. Following attainment of the required extent of functionalization and exfoliation, the unreacted 03, BX3, SF6 and C02 can be easily removed as gases by decompression leaving behind the solid phase, thereby leading to efficient and economical production of functionalized and exfoliated 2D layered materials.

A method includes contacting a metallic compound comprising a first metallic cation, with a melt comprising a metallic polysulfide comprising a second metallic cation, thereby forming a molten metallic polysulfide of the first metallic cation. The method also includes cooling the melt to form a sulfur phase and a solid phase comprising the molten metallic polysulfide of the first metallic cation.

A method includes contacting a metallic compound comprising a first metallic cation, with a melt comprising a metallic polysulfide comprising a second metallic cation, thereby forming a molten metallic polysulfide of the first metallic cation. The method also includes cooling the melt to form a sulfur phase and a solid phase comprising the molten metallic polysulfide of the first metallic cation.

The present invention relates to a process for dissolving metals in perhalide containing ionic liquids, and to the extraction of metals from mineral ores; the remediation of materials contaminated with heavy, toxic or radioactive metals; and to the removal of heavy and toxic metals from hydrocarbon streams.