NOVELTY - A lithium ion secondary battery comprises a positive electrode (1) of absorbing/releasing lithium, a negative electrode (2) of absorbing/releasing lithium and an electrolyte, where the negative electrode has a negative electrode active material which contains a non-graphitizing carbon (50-90 wt.%) and a graphitizing carbon (10-50 wt.%) which is coated on the surface with the non-graphitizing carbon. The average grain size of the graphitizing carbon is larger than the average grain size of the non-graphitizing carbon.    USE - As a lithium ion secondary battery used in hybrid cars, electric cars, and portable equipment such as personal computers and cellular phones.    ADVANTAGE - The lithium ion secondary battery has improved energy density, power density and excellent high rate cycle characteristics. By mixing the non-graphitizing carbon and the graphitizing carbon at a ratio of 90-50 wt.%:10-50 wt.%, the negative electrode mix density is improved, the resistance is decreased, and the power density is improved as initial characteristics. Further, the energy density is improved by the decrease of the irreversible capacity. By coating the surface of the graphitizing carbon with the non-graphitizing carbon of 10-100 nm thickness, the resistance is decreased and high rate cycle characteristics are improved. The graphitizing carbon can maintain high rate cycle characteristics suitable to car-mounting application by mixing with the non-graphitizing carbon. By the use of a mixed negative electrode of the non-graphitizing carbon and the graphitizing carbon, improvement in the energy density is achieved due to decrease of the irreversible capacity and improvement in the power density is achieved due to increase of the electrode area in the battery casing by the increase of the negative electrode mix density, which decreases the resistance as the initial characteristics.    DETAILED DESCRIPTION - A lithium ion secondary battery comprises a positive electrode (1) of absorbing/releasing lithium, a negative electrode (2) of absorbing/releasing lithium and an electrolyte, where the negative electrode has a negative electrode active material which contains a non-graphitizing carbon (50-90 wt.%) and a graphitizing carbon (10-50 wt.%) which is coated on the surface with the non-graphitizing carbon. The average grain size of the graphitizing carbon is larger than the average grain size of the non-graphitizing carbon. The graphitizing carbon has a layer containing the non-graphitizing carbon on the surface. The thickness of the layer is 10-100 nm. The spacing d(002) of the non-graphitizing carbon is greater than or equal to 0.360 nm and the spacing d(002) of the graphitizing carbon is 0.339 to less than 0.360.    DESCRIPTION OF DRAWING(S) - The figure shows a side-elevational cross-sectional view of a lithium ion secondary battery.    Positive electrode (1)    Negative electrode (2)    Separator (3)    Battery casing (4)    Battery lid (9)