1. Key Laboratory of Carbon Materials, Institute of Coal Chemistry; Chinese Academy of Sciences; Taiyuan 030001 People's Republic of China
2. University of Chinese Academy of Sciences; Beijing 100049 People's Republic of China
3. National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry; Chinese Academy of Sciences; Taiyuan 030001 People's Republic of China
4. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry; Chinese Academy of Sciences; Taiyuan 030001 People's Republic of China