A method of making SiC nanowires comprising: (a) mixing silicon powder with a carbon-containing biopolymer and a catalyst at room temperature to form a mixture; and (b) heating said mixture to a pyrolyzing temperature sufficient to react said biopolymer and said silicon power to form SiC nanowires.

Inside a furnace body with a vacuum environment or under the inert gas protection, the raw silicon material used to produce silicon carbide is melted or vaporized in a high temperature environment over 1300 C., and then the melted or vaporized raw silicon material will react with the carbonaceous gas or liquid to form silicon carbide. The present invention uses the carbonaceous gas with no metallic impurities, to replace petroleum coke, resin, asphalt, graphite, carbon fiber, coal, charcoal and some other carbon sources used in current production processes. When the carburizing reaction is in progress, the raw silicon material is melted or vaporized and the reaction takes place in the air. No container is required, so impurity contamination is lessened, and the produced silicon carbide has a fairly high purity.

A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000 C. to 1600 C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

A method for removing boron is provided, which includes (a) mixing a carbon source material and a silicon source material in a chamber to form a solid state mixture, (b) heating the solid state mixture to a temperature of 1000 C. to 1600 C., and adjusting the pressure of the chamber to 1 torr to 100 torr. The method also includes (c) conducting a gas mixture of a first carrier gas and water vapor into the chamber to remove boron from the solid state mixture, and (d) conducting a second carrier gas into the chamber.

The disclosure relates to a device for continuously producing qualitatively high-grade crystalline silicon carbide, in particular in the form of nanocrystalline fiber.

According to an exemplary embodiment of the present disclosure, a negative electrode active material includes metal-silicon-carbon based particles including a M.sub.aSi.sub.bC matrix, wherein M in the M.sub.aSi.sub.bC matrix is one or more selected from the group consisting of Li, Mg, Na, Ca, and Al, 0.35?a?1, and 1?b?2. Since at the time of charging and discharging a battery, formation of an irreversible phase may be minimized by the M.sub.aSi.sub.bC matrix, initial efficiency of the battery may be improved, and electrical conductivity, physical strength, and chemical stability may be improved, such that capacity and lifecycle characteristics of the battery may be improved.

According to an exemplary embodiment of the present disclosure, a negative electrode active material includes metal-silicon-carbon based particles including a M.sub.aSi.sub.bC matrix, wherein M in the M.sub.aSi.sub.bC matrix is one or more selected from the group consisting of Li, Mg, Na, Ca, and Al, 0.35?a?1, and 1?b?2. Since at the time of charging and discharging a battery, formation of an irreversible phase may be minimized by the M.sub.aSi.sub.bC matrix, initial efficiency of the battery may be improved, and electrical conductivity, physical strength, and chemical stability may be improved, such that capacity and lifecycle characteristics of the battery may be improved.

Provided in the embodiments of the present invention is an anode active substance for secondary batteries, which substance comprises a composite material. The composite material includes silicon particles, a ceramic material formed on at least some areas of the surface of the silicon particles, and a conductive carbon composite material formed on the ceramic material to cover the silicon particles and the ceramic material. In addition, further provided herein are a method for preparing an anode active substance and a lithium secondary battery prepared on the basis of the anode active substance.

A silicon carbide ingot is provided, which includes a seed end, and a dome end opposite to the seed end. In the silicon carbide ingot, a ratio of the vanadium concentration to the nitrogen concentration at the seed end is in a range of 5:1 to 11:1, and a ratio of the vanadium concentration to the nitrogen concentration at the dome end is in a range of 2:1 to 11:1.

A method of making SiC nanowires comprising: (a) mixing silicon powder with a carbon-containing biopolymer and a catalyst at room temperature to form a mixture; and (b) heating said mixture to a pyrolyzing temperature sufficient to react said biopolymer and said silicon power to form SiC nanowires.