| 摘要 |
Powder for a negative-electrode material of a lithium-ion secondary battery, which has conductive carbon film formed on the surface of lower silicon-oxide powder, and which is characterized in satisfying a relationship of 0.01 = Fa = 0.4, wherein Fa is the average value of F of 10 particles, F is a coefficient of variation of the thickness of the carbon film and is defined as F = s/ta, and ta is the average value and s is the standard deviation of the thickness of the conductive carbon film measured at 24 points of a particle of the lower silicon-oxide powder. The proportion of the conductive carbon film is preferably a mass percent of 0.5% to 10%. The total content of tar constituent measured with a TPD-MS is preferably a mass ppm of 1 ppm to 3500 ppm, and the resistivity is preferably not more than 10,000 Ocm. The maximum value (P1) of a halo due to SiOx derived by an XRD measurement, and a peak value (P2) of the strongest line of Si(111) preferably satisfy a relationship of P2/P1 < 0.01. With such a configuration, powder for a negative-electrode material to be used in a lithium-ion secondary battery that has large discharging capacity, good cycling characteristic, and that can withstand practical-level usage, is able to be provided. |
