A method can include milling a plurality of silicon particles to form a plurality of milled silicon particles. The milled silicon particles can optionally include collecting the milled silicon particles, powdering the milled silicon particles, and milling the milled silicon particles a second time.

A method can include milling a plurality of silicon particles to form a plurality of milled silicon particles. The milled silicon particles can optionally include collecting the milled silicon particles, powdering the milled silicon particles, and milling the milled silicon particles a second time.

The present invention relates to a negative active material for a lithium secondary battery, a preparation method therefor, and a lithium secondary battery including the same. The negative electrode active material is a negative electrode material for a secondary battery, the negative electrode active material comprising a silicon-carbon composite comprising: a core comprising crystalline carbon and silicon particles; and an amorphous carbon-containing coating layer disposed on a surface of the core, wherein the negative electrode active material comprises: silicon oxide formed on a surface of the silicon particles; and an oxide of crystalline carbon, formed on a surface of the crystalline carbon, the average particle diameter (D50) of the silicon particles having a nanometer size, the proportion of O relative to Si in the silicon oxide is 30%-50%, and the proportion of O relative to C in the oxide of the crystalline carbon is 4%-10%.

A polycrystalline silicon block fracture device includes a fracturing part mechanically fracturing a polycrystalline silicon block material to produce a polycrystalline silicon fragment including a polycrystalline silicon powder having a particle size of 500 to 1000 μm then discharging from a discharging port; a falling movement part continuous with a downstream of the fracturing part allowing said polycrystalline silicon fragment discharged from the discharging port to fall by gravity; a receiver part positioned at downstream of the falling movement part and receives the polycrystalline silicon fragment after falling through the falling movement part; and the falling movement part includes a suction removing part in which at least part of the polycrystalline silicon powder included in the polycrystalline silicon fragment is removed by suctioning to a different direction from falling direction; the suction removing part suctions at a suction rate of 1 to 20 m.sup.3/min.

A polycrystalline silicon block fracture device includes a fracturing part mechanically fracturing a polycrystalline silicon block material to produce a polycrystalline silicon fragment including a polycrystalline silicon powder having a particle size of 500 to 1000 μm then discharging from a discharging port; a falling movement part continuous with a downstream of the fracturing part allowing said polycrystalline silicon fragment discharged from the discharging port to fall by gravity; a receiver part positioned at downstream of the falling movement part and receives the polycrystalline silicon fragment after falling through the falling movement part; and the falling movement part includes a suction removing part in which at least part of the polycrystalline silicon powder included in the polycrystalline silicon fragment is removed by suctioning to a different direction from falling direction; the suction removing part suctions at a suction rate of 1 to 20 m.sup.3/min.

A silicon material can include a silicon aggregate comprising a plurality of porous silicon nanoparticles welded together. The silicon aggregate can optionally have a polyhedral morphology. A method can include: receiving a plurality of porous silicon nanoparticles and cold welding the plurality of porous silicon nanoparticles into an aggregated silicon particle.

A silicon material can include a silicon aggregate comprising a plurality of porous silicon nanoparticles welded together. The silicon aggregate can optionally have a polyhedral morphology. A method can include: receiving a plurality of porous silicon nanoparticles and cold welding the plurality of porous silicon nanoparticles into an aggregated silicon particle.

Provided is a copper alloy powder which is a metal powder to be used for additive manufacturing by a laser beam system, and which is able to achieve a higher laser absorption rate and additionally suppress heat transfer through necking, and a method for producing this copper alloy powder. A copper alloy powder which contains one or more elements selected from among Cr, Zr and Nb in a total amount of 15 wt % or less, with a balance being made up of Cu and unavoidable impurities, and which is characterized in that a coating film containing Si atoms is formed on the copper alloy powder, and a Si concentration in the copper alloy powder with the coating film is 5 wt ppm or more and 700 wt ppm or less.

A layered solid formulation (100a) as one hydrogen supply material (200) according to the present invention includes silicon fine particles having a capability of generating hydrogen and aggregates of the silicon fine particles, and a physiologically acceptable medium (90b) that gets contact with the silicon fine particles or the aggregates thereof. The hydrogen supply material (200) is a hydrogen supply material for bringing the hydrogen into contact with the skin and/or the mucous membrane through the medium (90b).

A layered solid formulation (100a) as one hydrogen supply material (200) according to the present invention includes silicon fine particles having a capability of generating hydrogen and aggregates of the silicon fine particles, and a physiologically acceptable medium (90b) that gets contact with the silicon fine particles or the aggregates thereof. The hydrogen supply material (200) is a hydrogen supply material for bringing the hydrogen into contact with the skin and/or the mucous membrane through the medium (90b).