Fabrication of B, N and P co-doped hollow carbon spheres with controllable shell thickness for high-performance supercapacitor

A facile strategy has been developed for preparing B, N, P co-doped hollow carbon spheres (BNP-HCSs) with adjustable shell thicknesses through a straightforward pyrolysis process of poly (styrene-co-(2-(dimethylamino)ethyl methacrylate))@boronate polymers. The shell thickness of the BNP-HCSs can be relatively controlled by manipulating the monomer concentration. The BNP-HCSs with a moderate shell thickness of 24 nm (BNP-HCS 24 ) exhibits a high capacitance of 357.4 F/g in a 1 M H 2 SO 4 electrolyte at 0.2 A/g. Furthermore, by analyzing the slopes of the discharge curves, we investigate the contributions of faradaic capacitance and electric double-layer capacitance (EDLC) to the total specific capacitance. The results indicate that faradaic capacitance is primarily linked to the effective utilization of heteroatoms, whereas EDLC capacitance correlates with the effective utilization of the BET surface area. The symmetrical two-electrode supercapacitor based on BNP-HCS 24 electrodes delivers an energy density of 8.16 Wh/kg at a power density of 125 W/kg. This study presents a valuable approach for fabricating heteroatom co-doped hollow carbon spheres with tunable shell thicknesses, offering a potential pathway to enhance supercapacitance performance through tailored carbon shell thicknesses. Moreover, the insight into the contributions of EDLC and faradaic capacitance is pivotal for the future development of heteroatom-doped carbon materials for supercapacitors.