To provide an electrode with high discharging capacity and high repeating charging/discharging characteristics by using carbon fibers in which the ratio of oxygen atoms to carbon atoms in the vicinity of the surface is specified and the size of a crystallite is specified as an active material.
As the active material of the electrode of a secondary battery, carbon fiber powder capable of pouring/releasing lithium ions is used. The carbon fibers in which the ratio of oxygen atoms to carbon atoms in the vicinity of the surface is 10% or less, preferably 6% or less, and preferably the ratio of nitrogen atoms to carbon atoms is 3% or less, and the size of crystallite (LC) is 1.0-5.0nm, preferably 1.0-2.5nm are used. The carbon fibers are obtained by forming amorphous carbon fibers in short fibers if necessary, then heat- treating the amorphous carbon fibers under the atmosphere of reduced pressure and/or the inert gas atmosphere at 700-1600°C, preferably at 1000-1500°C for one minutes to 50 hours, preferably 30 minutes to 8 hours.
SAKUMA ISAMU
SHIMOYAMA NAOKI
OKA TETSUO
TANIGUCHI MASAHIDE
HASHISAKA KAZUHIKO
TSUKAMOTO JUN
