| 摘要 |
PURPOSE:To increase charge/discharge capacity by using a carbon fiber with irregular surface whose center line average roughness (Ra) is a specified value or more. CONSTITUTION:Ra on the surface of a carbon fiber is limited to 4nm or more, preferably 5nm or more but 25nm or less to increase specific surface area. The contact area with an electrolyte is increased and battery performance is enhanced. For example, polyacrylonitrile consisting of acrylonitrile and methacrylic acid is dissolved in dimethylsulfoxide to prepare a spinning solution, and the spinning solution is directly spinned in a hot coagulating bath to obtain an original yarn A. An original yarn B is prepared in almost the same process as the original yarn A except for bath temperature. The original yarns A and B are heated at 200-250 deg.C under a relaxation ratio of 5% as fire resistant treatment, and baked at 1100 deg.C (or at 900-1500 deg.C) for 5 minutes in the nitrogen atmosphere under a relaxation ratio of 5% to prepare the carbon fiber. By using the carbon fiber, an electrode with high capacity and a secondary battery using the electrode can be provided. |
