Nitrogen and sulfur co-doped carbon sub-micrometer sphere-based electrodes toward high-performance hybrid supercapacitors

The splendid electrochemical characteristics of electrode materials are crucial for achieving high-performance hybrid supercapacitors. In this study, homogeneously dispersed nitrogen and sulfur co-doped carbon (NSC) sub-micrometer spheres are synthesized under a facile polymerization reaction and subsequent carbonization treatment. The NSC sub-micrometer spheres deliver a commendable specific capacitance of 254.8F g−1 at 1 A g−1 along with fantastic cyclic capability benefiting from the rich heteroatoms doping and abundant sub-nanometer pores (<1 nm) on the surface. Besides, using the NSC sub-micrometer spheres as substrate, nickel phosphide (Ni2P) lamellas are in-situ grown on NSC by an effective strategy, which exhibit a decent capacity of 819 C g−1 at 1 A g−1 with 83.2% of capacity retention after 10,000 cycles at 10 A g−1. More importantly, the advanced hybrid supercapacitor fabricated by NSC anode and NSC/Ni2P cathode reveals a desirable energy density of 51.3 Wh kg−1 at 757 W kg−1 and maintains 41.9 Wh kg−1 at 18855 W kg−1 in 6 M KOH, demonstrating the great potential for energy storage applications.