| 摘要 |
PROBLEM TO BE SOLVED: To improve charge and discharge efficiency and cyclic life using it in a secondary battery by employing a graphitizing gaseous phase growth carbon fiber, in which a specific surface area is a specific value or less and pressurization treatment is done under a specific pressure. SOLUTION: A secondary battery negative electrode carbon fiber is set to a maximum of 3 m<2> /g in specific surface area. This carbon fiber is subjected to pressurization treatment under a pressure of 1,000 to 800 kgf/cm<2> after graphitizing treatment has been carried out. When the treatment pressure is lower than a lower limit, fiber cutting becomes insufficient, and processing for an electrode is made difficult. When it is higher than an upper limit, a graphitizing structure has a possibility of being destroyed by pressurization force, and a reversible capacity is significantly lowered by the repetition of charging and discharging when employed for a battery. As a pressurization treatment method, pressurization by hydrostatic pressure is preferred from the standpoint of fine powder hardly occurring. In addition, it is preferably that the average aspect ratio of carbon fiber be 2 to 30, and that the mean diameter be 1 to 10 microns. |
