Hierarchical MoS2/NiCo2S4@C urchin-like hollow microspheres for asymmetric supercapacitors

Abstract

Metal sulfides are intensively studied as one of the most predominant materials for supercapacitors owing to such unique advantages as low-cost, low electronegativity and high electrochemical activity, and the appropriate architecture of hybrid metal sulfides is believed to be very effective for fully utilizing their material merits and breaking through their limits of the low-rate capability and inferior cycling stability in supercapacitor applications. Herein, a high-performance supercapacitor based on carbon-coated MoS2/NiCo2S4 urchin-like hollow hybrid microspheres (MoS2/NiCo2S4@C HMSs) is prepared by a facile self-template method. And the high specific capacity of 250 mAh g−1 at 2 A g−1 and ultra-high rate capability of 91.1% at 40 A g−1 achieved with the resultant MoS2/NiCo2S4@C HMSs due to their hierarchical hollow hybrid structure and the protection from the coated carbon thin layer. With the MoS2/NiCo2S4@C HMSs as the positive electrode and active carbon as the negative electrode, asymmetric supercapacitors (ASCs) have been assembled, which exhibit a high energy density of 53.01 Wh kg−1 at the power density of 4.20 kW kg−1, an energy density of 36.46 Wh kg−1 even at the ultra-high power density of 73.75 kW kg−1, and excellent cycling stability of 90.1% after 10 000 cycles of charge–discharge tests at the current density of 10 A g−1.