Metal‐Organic Frameworks‐Derived NiS2/CoS2/N‐Doped Carbon Composites as Electrode Materials for Asymmetric Supercapacitor.

Transition metal sulfides derived from metal‐organic frameworks (MOFs) have received increasing attention as a potential energy storage electrode material. Here, a series of NiS2/CoS2/NC‐T (T=temperature) have been successfully constructed by carbonizing and sulfuring the precursor of Ni/Co‐MOF. It is worth emphasizing that N‐doped carbon materials improve the conductivity of the electrode material. Moreover, NiS2/CoS2/NC‐500 maintains the rod‐like structure of the precursor and exhibits a high specific capacitance of 1325 F g−1 at a current density of 1 A g−1. Apart from high capacitance, the NiS2/CoS2/NC‐500 also demonstrated excellent cycling stability with retention rate of 75 % after 5000 cycles at a current density of 5 A g−1. The good performance could be attributed to the unique rod‐like structure and pore‐size distribution of NiS2/CoS2/NC‐500. Moreover, an assembled asymmetric supercapacitor NiS2/CoS2/NC‐500//AC displays a high energy density of 53.93 Wh kg−1 at a power density of 800 W kg−1 and good cycle stability with capacitance retention of 85.71 % after 20,000 cycles at 5 A g−1. In particular, a red LED can be illuminated by the assembled ASC, indicating that as‐synthesized NiS2/CoS2/NC‐500 hold great potential for practical applications. [ABSTRACT FROM AUTHOR]