Recyclable molten-salt-assisted synthesis of N-doped porous carbon nanosheets from coal tar pitch for high performance sodium batteries

N-doped porous carbon nanosheets (NPCS) are fabricated by a facile recyclable molten salt strategy with low-cost coal tar pitch as precursor. The obtained NPCS is featured with a continuous conductive network with a high nitrogen content of 5.22 at.%, facilitating the migration of electrons and ions in the process of sodium ion insertion/de-insertion. Benefiting from its appropriate structure and chemical composition, NPCS exhibits a high reversible capacity of 313.6 mAh g-1 at 0.1 A g-1 in sodium-ion half cells and excellent rate capability of 131.5 mAh g-1 at large current of 10 A g-1. Meanwhile, the full cell assembled by Na3V2(PO4)3 cathode and NPCS anode can deliver a high capacity of 220.1 mAh g-1 at 0.1 A g-1, and its capacity only attenuates 0.003 % in each cycle after 1000 times at 1.0 A g-1. The cleanness and massive utilization of coal tar pitch via eco-friendliness approach will promote the development of high-performance electrodes in the field of sodium ion electrochemical storage technology.