Microwave-Mediated Stabilization and Carbonization of Polyacrylonitrile/Super-P Composite: Carbon Anodes with High Nitrogen Content for Lithium Ion Batteries

Most synthetic carbonaceous anode materials for lithium-ion batteries (LIBs) are fabricated through a two-step heat-treatment process involving stabilization and carbonization. In this study, the stabilization and carbonization processes were accomplished via microwave treatment in significantly reduced time to fabricate carbonaceous anode materials for LIBs. Polymeric precursors for carbon materials, such as polyacrylonitrile (PAN), cannot be heat treated via the microwave because of their weak microwave-absorption properties. To address the issue, Super-P, carbon nanoparticles with an excellent microwave absorbing property, was adopted as a microwave initiator. On mixing a small amount of Super-P with PAN, Super-P acted as an efficient microwave absorber, and the temperature of the PAN/Super-P composite rapidly increased upon microwave treatment. Consequently, the stabilization time was reduced from 60 to 30 min when microwave irradiation was used to heat the PAN/Super-P composite. More significantly, the carbon sample could be fabricated by using only 1 min of microwave treatment, whereas convection heating required more than 200 min. Additionally, the carbonaceous materials obtained after microwave heating over shorter time periods were endowed with a high nitrogen content. The nitrogen content of microwave-heated carbon was 8.89%, whereas that of the convection carbonized counterpart was only 4.63%. Both pyridinic and graphitic nitrogen, which have been reported to improve the electrochemical performance, were noticeably higher in microwave-heated carbon. The synthesized microwave-assisted carbon material exhibited notable enhancements in the reversible capacity, rate performance, and cyclic stability. In summary, microwave-assisted stabilization and carbonization techniques offer options for the fast production of carbon anodes with excellent electrochemical performance and may be used for developing practical and high-performance battery anodes.