Preparation of pitch-based carbon microbeads by a simultaneous spheroidization and stabilization process for lithium-ion batteries

Owing to the special morphology, structure and wide application fields, carbon microbeads have gained great attention in these years. In this work, using a low-cost coal tar pitch as the raw material, we have developed a simultaneous spheroidization and stabilization approach to prepare pitch-based carbon microbeads (PCB). During preparation, the spheroidization and stabilization proceed simultaneously by introducing air to promote cross-linking. The coalescence of the low softening-point pitch in emulsion is avoided and there is no need for post-treatment to stabilize the spherical morphology. The effects of emulsion conditions such as the temperature, gaseous environment and holding time on the formation and structure of microbeads are investigated. It is demonstrated that the high emulsifying temperature, air blowing and long soaking time would benefit the introduction of oxygen to promote cross-linking among different aromatic molecules, which can stabilize the structures and maintain the spherical morphology. When used as anode materials for lithium ion batteries, PCB exhibit the superior cyclability and rate performance with gravimetric specific capacity of 373.6 and 125.8 mA h g−1 and volumetric capacities of 316.1 and 106.4 mA h cm−3 at the current densities of 0.05 and 5 A g−1, respectively.