| 摘要 |
PROBLEM TO BE SOLVED: To reduce the lowering of battery capacity, thereby keeping the preservable property in a good condition by using an electrode of a carbon material as an active material, in which the surface of a first carbon material serving as a core material is covered with a second carbon material incorporating boron, as a negative electrode of a secondary battery. SOLUTION: The surface of the first carbon material serving as the core material is covered with the second carbon material incorporating the boron in the range of 1 to 15 wt.%, preferably 5 to 10 wt.%, and the electrode of this carbon material as the active material is used as the negative electrode of the secondary battery of a nonaqueous electrolyte. The first carbon material does not incorporate the boron, is >=3.35 Å and <=3.38 Å in spacing (d002) of (002) planes measured by means of the X-ray wide-angle analysis method and is >=300 Å in size (Lc) of crystallites of crystals in the direction of an axis C. The second carbon material is preferably >=3.37 Åand <=3.90 Å in spacing (d002) of the (002) planes measured by means of the X-ray wide-angle analysis method. The quantity ratio of the second carbon material to the sum of the first carbon material and the second carbon material is controlled to be >=5 wt.% and <=10 wt.%. |
