Disclosed is a process for producing silicon nanowires having a diameter or thickness less than 100 nm, comprising: (A) preparing a solid silicon source material in a particulate form having a size from 0.2 μm to 20 μm or in a porous structure form having a specific surface area greater than 50 m.sup.2/g; (B) depositing a catalytic metal, in the form of nano particles having a size from 0.5 nm to 100 nm or a coating having a thickness from 1 nm to 100 nm, onto surfaces of the silicon source material to form a catalyst metal-coated silicon material; and (C) exposing the catalyst metal-coated silicon material to a high temperature environment, from 300° C. to 2,000° C., for a period of time sufficient to enable a catalytic metal-catalyzed growth of multiple silicon nanowires from the silicon source material.

Disclosed is a process for producing silicon nanowires having a diameter or thickness less than 100 nm, comprising: (A) preparing a solid silicon source material in a particulate form having a size from 0.2 μm to 20 μm or in a porous structure form having a specific surface area greater than 50 m.sup.2/g; (B) depositing a catalytic metal, in the form of nano particles having a size from 0.5 nm to 100 nm or a coating having a thickness from 1 nm to 100 nm, onto surfaces of the silicon source material to form a catalyst metal-coated silicon material; and (C) exposing the catalyst metal-coated silicon material to a high temperature environment, from 300° C. to 2,000° C., for a period of time sufficient to enable a catalytic metal-catalyzed growth of multiple silicon nanowires from the silicon source material.

Highly porous synergistic combinations of silicon and carbon materials are provided, along with articles that incorporate such materials and processes for producing the materials. The compositions have novel properties and provide significant improvements in Coulombic efficiency, dilithiation capacity, and cycle life when used as anode materials in lithium battery cells including solid state batteries.

A production process for carbon-coated silicon material includes the steps of: a lamellar-silicon-compound production step of reacting CaSi.sub.2 with an acid to turn the CaSi.sub.2 into a lamellar silicon compound; a silicon-material production step of heating the lamellar silicon compound at 300° C. or more to turn the lamellar silicon compound into a silicon material; a coating step of coating the silicon material with carbon; and a washing step of washing the silicon material, or another silicon material undergone the coating step, with a solvent of which the relative permittivity is 5 or more.

A production process for carbon-coated silicon material includes the steps of: a lamellar-silicon-compound production step of reacting CaSi.sub.2 with an acid to turn the CaSi.sub.2 into a lamellar silicon compound; a silicon-material production step of heating the lamellar silicon compound at 300° C. or more to turn the lamellar silicon compound into a silicon material; a coating step of coating the silicon material with carbon; and a washing step of washing the silicon material, or another silicon material undergone the coating step, with a solvent of which the relative permittivity is 5 or more.

A production process for carbon-coated silicon material includes the step of: heating CaSi2 and a halogen-containing polymer at a temperature being a carbonization temperature or more of the halogen-containing polymer in a state where the CaSi2 and the halogen-containing polymer coexist.

A production process for carbon-coated silicon material includes the step of: heating CaSi2 and a halogen-containing polymer at a temperature being a carbonization temperature or more of the halogen-containing polymer in a state where the CaSi2 and the halogen-containing polymer coexist.

Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight of silicon particles. The silicon particles have an average particle size between about 0.1 μm and about 30 μm and a surface including nanometer-sized features. The composite material also includes greater than 0% and less than about 90% by weight of one or more types of carbon phases. At least one of the one or more types of carbon phases is a substantially continuous phase.

Silicon particles for active materials and electro-chemical cells are provided. The active materials comprising silicon particles described herein can be utilized as an electrode material for a battery. In certain embodiments, the composite material includes greater than 0% and less than about 90% by weight of silicon particles. The silicon particles have an average particle size between about 0.1 μm and about 30 μm and a surface including nanometer-sized features. The composite material also includes greater than 0% and less than about 90% by weight of one or more types of carbon phases. At least one of the one or more types of carbon phases is a substantially continuous phase.

A porous amorphous silicon which enables improvement in battery performances such as charge/discharge efficiency and battery capacity when used as the anode material; a method for producing a porous amorphous silicon, capable of producing a porous amorphous silicon composed entirely of amorphous silicon at relatively low cost in a short time; and a secondary battery using the porous amorphous silicon as the anode material. A molten metal containing metal and silicon is cooled at a cooling rate of 10.sup.6 K/sec or more to form an eutectic alloy including the metal and the silicon, and then the metal is selectively eluted from the eutectic alloy with an acid or an alkali to obtain a porous amorphous silicon. The porous amorphous silicon has a lamellar or columnar structure having a mean lamellar diameter or a mean column diameter of 1 nm to 100 nm.