A silicon material can include a composition with at least about 50% silicon, at most about 45% carbon, and at most about 10 % oxygen. The silicon material can have an external expansion that is less than about 40%. The silicon material can include silicon nanoparticles, which can cooperatively form clusters. The silicon nanoparticles can be porous.

A silicon material can include a composition with at least about 50% silicon, at most about 45% carbon, and at most about 10 % oxygen. The silicon material can have an external expansion that is less than about 40%. The silicon material can include silicon nanoparticles, which can cooperatively form clusters. The silicon nanoparticles can be porous.

A thermoelectric material includes a parent phase in which an MgSiSn alloy is a main component, a void formed in the parent phase, and a silicon layer that is formed on at least a wall surface of the void and that includes silicon as a main component. The thermoelectric material further includes MgO in an amount of 1.0 wt. % or more and 20.0 wt. % or less. The silicon layer includes amorphous Si, or amorphous Si and nanosized Si crystals, and the parent phase includes a region in which the composition ratio of the Si of the chemical composition of the MgSiSn alloy is higher than in the other regions and a region in which the composition ratio of the Sn of the chemical composition of the MgSiSn alloy is higher than in the other regions. With these configurations, the thermoelectric material realizes both lower thermal conductivity and lower electrical resistivity.

A crushed polycrystalline silicon lump is provided in which a surface metal concentration is 15.0 pptw or less and preferably 7.0 to 13.0 pptw, and in the surface metal concentration, a surface tungsten concentration is 0.9 pptw or less and preferably 0.40 to 0.85 pptw, and a surface cobalt concentration is 0.3 pptw or less and preferably 0.04 to 0.08 pptw.

A solid electrolyte interface is formed on a silicon monoxide electrode in a battery cell. While the solid electrolyte interface is being formed on the silicon monoxide electrode, the battery cell is charged for one or more initial cycles.

A solid electrolyte interface is formed on a silicon monoxide electrode in a battery cell. While the solid electrolyte interface is being formed on the silicon monoxide electrode, the battery cell is charged for one or more initial cycles.

Disclosed are a silicon-aluminum alloy and its preparation method. The method comprises: adding aluminum metal or molten aluminum into a container, wherein the temperature of the molten aluminum is between 700° C. and 800° C.; adding a semi-metallic silicon raw material to the molten aluminum, closing a furnace cover, carrying out vacuumization, and introducing argon, to ensure that the interior of a magnetic induction furnace is in a positive-pressure state, and stirring the aluminum metal or molten aluminum with a graphite stirring head; powering on and heating so that the aluminum metal or molten aluminum is heated to 1000° C. or above and molten, and holding the temperature between 1000° C. and 1500° C.; and after alloying is completed, cooling the molten aluminum to 1000° C. or below, opening the furnace cover, pouring the silicon-aluminum alloy into a corresponding mold, and cooling for molding.

Disclosed are a silicon-aluminum alloy and its preparation method. The method comprises: adding aluminum metal or molten aluminum into a container, wherein the temperature of the molten aluminum is between 700° C. and 800° C.; adding a semi-metallic silicon raw material to the molten aluminum, closing a furnace cover, carrying out vacuumization, and introducing argon, to ensure that the interior of a magnetic induction furnace is in a positive-pressure state, and stirring the aluminum metal or molten aluminum with a graphite stirring head; powering on and heating so that the aluminum metal or molten aluminum is heated to 1000° C. or above and molten, and holding the temperature between 1000° C. and 1500° C.; and after alloying is completed, cooling the molten aluminum to 1000° C. or below, opening the furnace cover, pouring the silicon-aluminum alloy into a corresponding mold, and cooling for molding.

Methods for producing nanostructures from copper-based catalysts on porous substrates, particularly silicon nanowires on carbon-based substrates for use as battery active materials, are provided. Related compositions are also described. In addition, novel methods for production of copper-based catalyst particles are provided. Methods for producing nanostructures from catalyst particles that comprise a gold shell and a core that does not include gold are also provided.

Methods for producing nanostructures from copper-based catalysts on porous substrates, particularly silicon nanowires on carbon-based substrates for use as battery active materials, are provided. Related compositions are also described. In addition, novel methods for production of copper-based catalyst particles are provided. Methods for producing nanostructures from catalyst particles that comprise a gold shell and a core that does not include gold are also provided.