Patent ID: 7858239

Claim:
A negative electrode material which is a non-graphitizable carbon having a small diffusibility of helium, for non-aqueous electrolyte secondary batteries, said negative electrode material having at least one exothermic peak in the range of not lower than 650° C. and lower than 700° C., and at least one exothermic peak in the range of not lower than 700° C. and lower than 760° C., in differential thermal analysis measured under an air flow; an average interlayer spacing d 002 determined by X-ray diffraction method of not less than 0.365 nm and not more than 0.370 nm; a true density (ρH) measured according to the gas displacement method defined in JIS R1620(4) using helium as a displacement medium of not less than 1.6 g/cm 3 and not more than 1.8 g/cm 3 ; an equilibrium water adsorption measured according to JIS K1469 of not more than 1% by weight; a discharge capacity of not less than 60 mAh/g and less than 115 mAh/g per 1 g at an electric potential of 0.1V in counter electrode lithium evaluation; a discharge capacity of not less than 200 mAh/g and less than 300 mAh/g per 1 g at an electric potential of 1.5V in counter electrode lithium evaluation; and a difference (irreversible capacity) between the capacity required for lithium doping and the capacity required for lithium dedoping of not more than 60 mAh/g and wherein said negative electrode material is obtained from negative electrode material precursor having an oxygen content of not less than 5% by weight and less than 10% by weight.