Abstract: A lithium-ion secondary battery negative electrode mixture includes a conductive additive and porous amorphous silicon particles including an amorphous silicon phase. The porous amorphous silicon particles have a lamellar structure including lamellar protrusions having an average thickness in a range of 1 nm or more and 200 nm or less, a columnar structure including columnar protrusions having an average diameter in a range of 1 nm or more and 100 nm or less, or a co-continuous structure including the lamellar protrusions and the columnar protrusions.

Abstract: 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 106 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.