Fabrication of Fe3C nanoparticles embedded in N-doped carbon nanotubes/porous carbon 3D materials derived from distilled grains for high performance of potassium ion battery

The design and fabrication of advanced carbon materials is highly important for potassium ion batteries. In this paper, Fe3C nanoparticles embedded in N-doped carbon nanotubes/porous carbon (Fe3C@N-CNPC) 3D materials were synthesized by pyrolysis of N-doped distilled grains in the presence of FeCl3/ZnCl2 activators. It was demonstrated that the FeCl3/ZnCl2 activators played an important role in the formation of Fe3C@N-CNPC 3D materials. On the one hand, the activator endowed the carbonaceous materials with a high proportion of micropores and large surface area. On the other hand, Fe nanoparticles generated by decomposition of FeCl3 catalyzed the growth of intertwined carbon nanotubes on porous carbon, yielding Fe3C@N-CNPC 3D materials with abundant porous structure and a high degree of graphitization. The as-prepared Fe3C@N-CNPC were used as anode materials for potassium ion batteries. Due to the synergistic effect of N-doping, superstructure, and large surface area, the Fe3C@N-CNPC based potassium ion batteries exhibited remarkable potassium storage capacity (273 mAh g−1 at 100 mA g−1) and excellent cycle stability (94% capacity retention at 100 mA g−1 after 570 cycles). This novel carbon material with low cost and ease preparation is of great significance for the application of potassium ion batteries. Meanwhile, our strategy also provides a reference idea for the resource utilization of the distilled grains waste.