| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative electrode active material in which the insertion and the desorption of lithium ions at a scale-like graphite flat plate portion edge on the surface of or inside of a negative electrode active material layer are conducted smoothly, and charge and discharge cycle characteristics and battery capacity are superior by mixing scale-like graphite and non-scale like carbon material, so as to disorder the orientation of the scale-like graphite. SOLUTION: The average area of a flat plate portion G1 is 5 to 1000μm<2> , particularly 10 to 500μm<2> , and average thickness is 5μm or less, particularly 1μm, preferably 0.2 to 0.3μm as scale-like graphite G. As carbon material such as crystalline carbon or graphite is preferable, since the insertion and the desorption of lithium ions can be reversibly conducted at the charge and discharge time of a battery. The amount of non-scale like carbon material of 5 to 100 parts by weight per 100 parts by weight of scale-like graphite G preferably produces proper scale-like graphite disorder. Thereby, since the expansion and contraction of a negative electrode active material layer is uniform, and the mixing existence of the scale-like graphite and the non-scale like carbon material absorbs and suppresses the expansion and contraction, it is possible to obtain a nonaqueous electrolyte lithium secondary battery, in which battery capacitor and cycle characteristics are superior. |
