▎ 摘　　要

NOVELTY - The negative electrode active material has a silicon nanowire (101) and a carbon coating layer (102) which is formed on a surface of the silicon nanowire. The carbon coating layer is provided with a nano graphene structure. The silicon nanowire is formed in the surface of the carbon base material which is Ketchen Black or acetylene black. The electrical conductivity of the carbon coating layer is 1000 S/m or more. The thickness of the carbon coating layer is 0.2-100 nm, and the diameter of silicon nanowire is 2-100 nm. USE - Negative electrode active material for lithium ion secondary battery (claimed). ADVANTAGE - The negative electrode active material for lithium ion secondary batteries can prevent electrical isolation of the silicon particle effectively. The irreversible capacity of the lithium ion secondary battery is reduced. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacturing method of negative electrode active material. DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the carbon covering silicon nanowire. Silicon nanowire (101) Carbon coating layer (102) Carbon covering silicon nanowire (202)