Nitrogen and phosphorus co-doped carbon for improving capacity and rate performances of potassium ion batteries

The carbon material is considered as the promising anode for potassium ion battery owing to the merits of wide source and structural robustness. However, the limited capacity and the slow kinetics limit the development of carbon materials. Herein, the porous nitrogen-and-phosphorus co-doped carbon material are prepared using the O2-NH3 reactive pyrolysis of cellulose with the additional phosphating treatment. As compared with the pristine carbon obtained by the direct pyrolysis of cellulose, the capacity of nitrogen-and-phosphorus co-doped carbon rises from 140 to 253 mAh g-1, and the capacity increases significantly even at high current density (from 16 to 76 mAh g-1 at 20 A g-1). Under the guidance of theoretical simulation, the enhancement of potassium storage capacity and kinetics is explored by combining spectral characterization and electrochemical research. On this basis, the synergistic effect of nitrogen and phosphorus co-doping can improve the potassium storage performance. This study has reference significant for heteroatom modification of carbon materials for potassium storage anodes.