Molten salt synthesis of nitrogen-doped carbon with hierarchical pore structures for use as high-performance electrodes in supercapacitors

Porous carbon materials have received considerable attention recently, particularly in the energy field. To meet the increasing demands for electrochemical energy conversion and storage-related applications, the development of novel porous carbon materials that show high electrochemical performances is highly desired. Here, a facile method for the preparation of nitrogen-doped hierarchically porous carbon materials is proposed. Cost-effective chitosan is selected as the nitrogen-containing carbon source, and the carbonation is realized in a ZnCl2 molten salt at a temperature range of 400-700 °C. Hierarchically porous carbon with a specific surface area of 1582 m2 g−1 and a high nitrogen content of 9.0 wt.% is obtained at a carbonation temperature of 600 °C with a high carbon yield of 42 wt.% based on the weight of chitosan. Importantly, using this as-synthesized carbon material as the electrode in supercapacitors, high specific capacitances of 252 and 145 F g−1 at current densities of 0.5 and 50 A g−1, respectively, and stable cycling performance without decay after 10,000 cycles at 8 A g−1 are realized. The facile synthesis, easy recovery of ZnCl2 and high carbon yield make this new method highly promising for the preparation of porous carbon materials for use in supercapacitors and other fields.