Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d 002) of the boron-doped graphitized CNFs reached 3.356, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d 002 is less than 3.400, were selected for further heat treatment. The first heat treatment of PCNFs at 2800°C yielded a d 002 between 3.357 and 3.365. Successive nitric acid treatment and a second heat treatment with boric acid reduced d 002 to 3.356. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338mAhg 1 between 0 and 0.5V versus Li/Li + and 368mAhg 1 between 0 and 1.5V versus Li/Li +. The first-cycle Coulombic efficiency was also enhanced to 71-80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Electrical and Electronic Engineering