Co1-xS/Co3S4@N,S-co-doped agaric-derived porous carbon composites for high-performance supercapacitors

Abstract

In recent years, pseudocapacitive transition metal sulfur compounds have received extensive attention as supercapacitor materials owing to their superior intrinsic conductivity. However, developing ideal structures that undergo fast Faraday redox reactions with ultra-long-term cycling performance is an important challenge. Using a homogeneous extract from agaric acid as a carbon source, a one-pot hydrothermal-assisted pyrolysis method was employed to prepare cobalt sulfide compounds. The results showed that Co1-xS/Co9S8 was generated without the addition of carbon source, while Co1-xS/Co3S4 was generated by the addition of agaric base. The prepared N,S-co-doped agaric-derived porous carbon (NSAC) nanocomposite that was densely decorated with (Co1-xS/Co3S4) to give a heterostructure(Co1-xS/Co3S4@NSAC). Co1-xS/Co3S4@NSAC exhibited high specific capacitance, as well as excellent rate capability and cycling stability performance (497.5 F g−1 at 0.5 A g−1, 96 F g−1 at 80 A g−1, with 96.9% capacity retention at 25 A g−1 for 6000 cycles). Symmetrical supercapacitors were fabricated using Co1-xS/Co3S4@NSAC, affording high energy density (17.7 Wh kg−1 at 598.9 W kg−1) and cycling retention (109% capacity retention at 5 A g−1 for 4000 cycles). Based on the experimental results and density functional theory (DFT) calculations, the Co1-xS/Co3S4 heterojunction interface allows for highly reversible and efficient electrochemical redox processes, with fast charge transfer kinetics and structural stability during the electrochemical reactions.