Nitrogen-doped porous carbon derived from foam polystyrene as an anode material for lithium-ion batteries

Abstract N-doped porous carbons (NPCs) prepared via carbonization of foam polymer materials and urea are promising anode materials of lithium-ion batteries (LIBs) for their low cost and high performance. Herein, polystyrene was mixed with Melanic Mc (5 wt%) and Azobisformamide (3 wt%) to prepared the precursors of porous carbon. NPCs with different N-doping levels were then obtained by the calcination of porous carbon/urea mixture with varied weight ratios. XPS and Raman characterizations illustrate that N-doping imposes negligible effects on the chemical states of N or C, but rather promotes the formation of disordered carbon and structural defects. BET measurement confirms that N-doping enlarges the surface area. The optimized NPCs with porous carbon/urea weight ratio of 1:5 exhibits high surface area of 508.3 m2·g−1 and the pore size is found to be around 3.66 nm. The capacities of NPCs achieve 600 mAh g−1 and 443 mAh g−1 over 200 cycles at 1 A g−1 and 5 A g−1 respectively. The excellent performance of NPC is ascribed to the enhanced surface area, defects and pores, providing abundant tunnels for lithium ion diffusion. Meanwhile, N-doping improves the electrical conductivity, which also enhances the rate performance. The facile synthetic route of NPCs as well as their excellent lithium storage performance shows great potential for the application in advanced lithium-ion batteries.