NEGATIVE ELECTRODE AND LITHIUM ION SECONDARY BATTERY USING THE ELECTRODE

摘要

PURPOSE: A negative electrode and a lithium ion secondary battery using the negative electrode are provided, to obtain a high capacity, an excellent high rate charge/discharge property and a small irreversible capacity. CONSTITUTION: The negative electrode comprises a carbon material-containing material mixture layer, wherein its has a carbon density of 1.6 g/cm2 or more obtained by dividing the weight of the material mixture layer with its volume, and the carbon material comprises a spherical natural graphite and 50-90 wt% of a graphitized carbon fiber. The spherical natural graphite has an interplanar spacing d002 between the (002) planes determined by an X-ray diffraction pattern of 0.3354-0.3357 nm, a mean particle circularity of 0.86 or more and a mean particle size of 5-20 micrometer; and the graphitized carbon fiber has a mean fiber length of 20-200 micrometers and a mean aspect ratio of 2-10.