A particle with a yolk-shell structure including a shell including carbon; and a care including silicon (Si) provided inside the shell, wherein at least a part of the shell is spaced apart from the core, and the particle with the yolk-shell structure has a micropore volume of 0.15 cm.sup.3/g or less, and a method for preparing the same.

The present invention relates to a method of preparing a porous silicon-based negative electrode active material comprising: mixing a porous silica (SiO.sub.2) and an aluminum powder; oxidizing all or part of the aluminum powder as an aluminum oxide while at the same time reducing all or part of the porous silica as a porous silicon (Si) by heat-treating a mixture of the porous silica with the aluminum powder, a negative electrode active material, and a rechargeable lithium battery including the same.

The present invention relates to a method of preparing a porous silicon-based negative electrode active material comprising: mixing a porous silica (SiO.sub.2) and an aluminum powder; oxidizing all or part of the aluminum powder as an aluminum oxide while at the same time reducing all or part of the porous silica as a porous silicon (Si) by heat-treating a mixture of the porous silica with the aluminum powder, a negative electrode active material, and a rechargeable lithium battery including the same.

A system and a method for producing silicon from a SiO.sub.2-containing material that includes solid SiO.sub.2. The method uses a reaction vessel including a first section and a second section in fluid communication with said first section. The method includes: heating the SiO.sub.2-containing material that includes the solid SiO.sub.2 to a SiO.sub.2-containing material that includes liquid SiO.sub.2, at a sufficient temperature to convert the solid SiO.sub.2 into the liquid SiO.sub.2; converting, in the first section, the liquid SiO.sub.2 into gaseous SiO.sub.2 that flows to the second section by reducing the pressure in the reaction vessel to a subatmospheric pressure; and reducing, in the second section, the gaseous SiO.sub.2 into liquid silicon using a reducing gas. The reducing of the pressure is performed over a continuous range of interim pressure(s) sufficient to evaporate contaminants from the SiO.sub.2-containing material, and removing by vacuum, the one or more evaporated gaseous contaminants.

A system and a method for producing silicon from a SiO.sub.2-containing material that includes solid SiO.sub.2. The method uses a reaction vessel including a first section and a second section in fluid communication with said first section. The method includes: heating the SiO.sub.2-containing material that includes the solid SiO.sub.2 to a SiO.sub.2-containing material that includes liquid SiO.sub.2, at a sufficient temperature to convert the solid SiO.sub.2 into the liquid SiO.sub.2; converting, in the first section, the liquid SiO.sub.2 into gaseous SiO.sub.2 that flows to the second section by reducing the pressure in the reaction vessel to a subatmospheric pressure; and reducing, in the second section, the gaseous SiO.sub.2 into liquid silicon using a reducing gas. The reducing of the pressure is performed over a continuous range of interim pressure(s) sufficient to evaporate contaminants from the SiO.sub.2-containing material, and removing by vacuum, the one or more evaporated gaseous contaminants.

A porous silicon composition, a porous alloy composition, or a porous silicon containing cermet composition, as defined herein. A method of making: the porous silicon composition; the porous alloy composition, or the porous silicon containing cermet composition, as defined herein. Also disclosed is an electrode, and an energy storage device incorporating the electrode and at least one of the disclosed compositions, as defined herein.

The present disclosure relates to a negative electrode material including, as an active material, silicon flakes with a hyperporous structure, represented by the following chemical formula 1:

xSi.(1x)A(1) where 0.5x1.0, and A is an impurity, and includes at least one compound selected from the group consisting of Al.sub.2O.sub.3, MgO, SiO.sub.2, GeO.sub.2, Fe.sub.2O.sub.3, CaO, TiO.sub.2, Na.sub.2O K.sub.2O, CuO, ZnO, NiO, Zr.sub.2O.sub.3, Cr.sub.2O.sub.3 and BaO, and a preparing method of the silicon flakes.

A process for preparing a highly pure silicon by reduction of a calcium silicate slag using a source of aluminium.

A process for preparing a highly pure silicon by reduction of a calcium silicate slag using a source of aluminium.

A method for producing amorphous silica includes: a pretreatment process of pulverizing vegetable material to obtain a silica source; a burning process of burning the silica source and extracting silica; and a purification process of removing carbon from burning material obtained in the burning process. The burning process includes a heating process of supplying an inert gas into a chamber and heating the silica source in the chamber in a plasma atmosphere.