Chemical Grafting-derived N, P Co-doped Hollow Microporous Carbon Spheres for High-Performance Sodium-ion Battery Anodes

Microstructure design combined with high-level heteroatoms doping has been considered the leading approach for preparing the high-performance carbon anodes for sodium-ion batteries (SIBs). Herein, a hollow porous carbon sphere (NP-HPCS) that exhibits a high N, P co-doping level (6.05 at% for N, 5.19 at% for P) and a large microporous specific area (339 m(2 )g(-1)) is reported. The microporous and N, P co-doping synergistic construction of the NP-HPCS was achieved by a high-efficiency chemical grafting of hexachlorocyclotriphosphazene (HCCP) onto polydopamine (PDA) shell, accompanied by the in situ micellar transformation of pore-forming agent F127 in the grafting process. The as-prepared NP-HPCS used as an anode for SIBs delivers a superior rate capacity (similar to 101 mAh g(-1) at 20 A g(-1)) and an excellent long cycle performance (similar to 120 mAh g(-1) after 5000 cycles at 5 A g(-1)). The kinetics analysis and density functional theory (DFT) calculations were carried out to further analyze the superior sodium storage performance of NP-HPCS. Our work suggests an effective way to develop high-performance carbon anode materials for SIBs.