Jx Nippon Oil Energy Corporation

Takefumi Kono

Takashi Suzuki

Noriyo Ishimaru

Provided is an amorphous carbon material for a negative electrode of a lithium ion secondary battery. The amorphous carbon material comprises a size of a crystallite Lc(002) in c-axis direction ranging from 2.0 to 8.0 nm, the size being calculated from a (002) diffraction line of the amorphous carbon material measured by powder X-ray diffractometry; a carbon-derived spectrum appearing in a range from 3,200 to 3,400 gauss (G) in an electron spin resonance measured using X band; a relative signal intensity ratio (I/I) of the spectrum ranging from 2.4 to 3.5, wherein the relative signal intensity ratio is a ratio of signal intensity (I) at temperature of 4.8 K to signal intensity (I) at temperature of 40K; and a line width (&#x394;Hpp) of the spectrum ranging from 70 to 180 gauss (G), wherein the line width is calculated from a first-order derivative spectrum at temperature of 4.8 K.

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Kanagawa, Japan

Takefumi Kono