The invention relates to a process for the production of silicon and alumina Aluminium is contacted with a molten slag of a calcium oxide and SiO.sub.2 under conditions facilitating an aluminothermic reaction, thereby forming silicon and an aluminate slag in two phases which are separated. The aluminate slag is converted to alumina and calcium oxide, which is re-fed in the reaction. The aluminium is provided by melting of aluminium scrap or a combination of different aluminium alloys at a temperature of 700 to 1000° C. The primary aluminium melt is adjusted to a content of 8 to 14% of silicon and then cooled to below 660° C., whereby precipitates are formed, and high purity aluminium is obtained to be introduced into the reaction.

Disclosed herein are embodiments of producing Si or SiO.sub.x from inexpensive silica sources. In some embodiments, plasma processing can be used to covert the silica sources to the silicon products. Unique morphologies can be formed in some embodiments. In some embodiments, reducing agents, catalysts, and/or salts can be used to provide advantageous properties.

A sulfur-doped silicon negative electrode material, a preparation method for a sulfur-doped silicon negative electrode material, a negative electrode for a lithium secondary battery comprising the sulfur-doped silicon negative electrode material, and a lithium secondary battery comprising the negative electrode, wherein the sulfur-doped silicon negative electrode material has an internal pore channel having an average width of 500 nm to 3 μm and an average external diameter of 1 μm to 5 μm.

A sulfur-doped silicon negative electrode material, a preparation method for a sulfur-doped silicon negative electrode material, a negative electrode for a lithium secondary battery comprising the sulfur-doped silicon negative electrode material, and a lithium secondary battery comprising the negative electrode, wherein the sulfur-doped silicon negative electrode material has an internal pore channel having an average width of 500 nm to 3 μm and an average external diameter of 1 μm to 5 μm.

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiO.sub.a (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite, and provides a negative electrode active material in which the crystal growth of crystalline silicon in a silicon-based composite prepared by thermal reduction with a metal reducing agent is suppressed in a state where a carbon coating layer is formed, and the ratio of silicon in the composite is high, and a method of preparing the same.

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiO.sub.a (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite, and provides a negative electrode active material in which the crystal growth of crystalline silicon in a silicon-based composite prepared by thermal reduction with a metal reducing agent is suppressed in a state where a carbon coating layer is formed, and the ratio of silicon in the composite is high, and a method of preparing the same.

The present invention relates to a negative electrode active material which includes a secondary particle including a first particle which is a primary particle, wherein the first particle includes a first core and a first surface layer which is disposed on a surface of the first core and contains carbon, and the first core includes a metal compound which includes one or more of a metal oxide and a metal silicate and one or more of silicon and a silicon compound; a method of preparing the same; an electrode including the same; and a lithium secondary battery including the same.

The invention relates to a method for the production of high-purity elementary silicon from a starting material containing silicon dioxide, which includes the steps of: a) thermal pre-purification of the starting material, wherein impurities from the group consisting of boron and phosphorus are separated essentially completely and a pre-purified silicon dioxide is obtained; b) reduction of the pre-purified silicon dioxide to elementary silicon; and c) removal of impurities remaining in the pre-purified silicon dioxide after step a) during and/or after step b).

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiO.sub.a (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite, and provides a negative electrode active material in which the crystal growth of crystalline silicon in a silicon-based composite prepared by thermal reduction with a metal reducing agent is suppressed in a state where a carbon coating layer is formed, and the ratio of silicon in the composite is high, and a method of preparing the same.

The present specification relates to a negative electrode active material including an amorphous silicon-based composite represented by SiO.sub.a (0<a<1); and a carbon coating layer distributed on a surface of the silicon-based composite, and provides a negative electrode active material in which the crystal growth of crystalline silicon in a silicon-based composite prepared by thermal reduction with a metal reducing agent is suppressed in a state where a carbon coating layer is formed, and the ratio of silicon in the composite is high, and a method of preparing the same.