Carbon Fibers with High Electrical Conductivity: Laser Irradiation of Mesophase Pitch Filaments Obtains High Graphitization Degree

Carbon fibers have promising applications in the efficient transmission of electric power with less resource consumption. Laser graphitization of the mesophase pitch-based carbon fiber (MPCF) was proposed to improve the electrical conductivity of the carbon fiber. The obtained MPCF showed a high conductivity of 7.04 × 105 S/m. The graphitization degree of carbon fiber increased and the interlayer spacing of its graphite crystal decreased on increasing the laser intensity. With a laser power of 360 W and an irradiation period of 25 s, corresponding to a temperature of 3001 °C, a high graphitization degree (R = 0.02) was obtained and the interlayer spacing was as small as 0.338 nm, close to that of pure graphitic carbon (0.335 nm). The enhanced electrical conductivity is attributed to the improved homogeneity of graphitization along the axial and radial directions, the ordered structural evolution, ordered stacking of the graphitic layer, and the promoted connectivity between the graphitic crystals in the carbon fiber. The energy consumption of the proposed method is estimated to be only 0.46% of that with the conventional Joule heating approach. This work suggests that laser-induced graphitization is a good alternative to prepare carbon fibers with high electrical conductivity and reduced energy consumption.