Patent ID: 8900749

Claim:
A negative electrode material powder for a lithium ion secondary battery having a conductive carbon film on the surface of a lower-silicon-oxide powder; wherein a specific surface area determined by the BET method ranges from more than 0.3 m 2 /g to 40 m 2 /g, and a SiC peak is immune from appearing at 2θ=35.6°±0.1° or the half-value width of the appeared peak is 2° or more, in measurement with an X-ray diffractometer using CuK α rays radiation, and in measurement with an XRD using Cuk α rays radiation, P2/P1<0.01 is satisfied, given that the highest value of halo due to SiO x that appears at 2θ=10° to 30° is P1 and a value of the strongest linear peak of Si (111) that appears at 2θ=28.4±0.3° above said halo is P2.