High-rate sodium ion anodes assisted by N-doped carbon sheets

Well-defined 3D nitrogen-doped porous carbon materials (NPCMs) have been obtained from CQDs and melamine by the self-assembly process, presenting a distinct textural structure with uniform N-doping distribution. The as-prepared NPCMs, as the anode materials for SIBs, display high specify capacity, long-term cyclability and good rate capacity. At 100 mA g −1 , the NPCM electrode can reach the first capacity of 225 mA h g −1 (204.7 mA h cm −2 ) and maintain 241.2 mA h g −1 (219.3 mA h cm −2 ) after 100 cycles. Even at the current density of 1000 mA g −1 , a reversible capacity of 130.2 mA h g −1 (118.9 mA h cm −2 ) can be retained, which can be attributed to the improved extrinsic defects and electrical conductivity resulting from N-doping.