One‐Step Synthesis of NiCo 2 S 4 /Graphene Composite for Asymmetric Supercapacitors with Superior Performances

Abstract To meet the demand of high‐performance electrode materials for supercapacitors, it is highly desirable to design and develop a new class of electrode materials with superior electrochemical performance. Here, we used a simple hydrothermal method to synthesize NiCo 2 S 4 ‐anchored graphene nanosheets (NiCo 2 S 4 /GNS) for high‐performance supercapacitors. Benefiting from the synergistic effect of graphene and NiCo 2 S 4 , the as‐prepared composite exhibits outstanding electrochemical performances, such as high specific capacitance (1063 F g −1 at current density of 2 A g −1 ) and excellent cycling performance while maintaining 82 % of the initial value after 10000 cycles. Furthermore, an asymmetric supercapacitor (ASC) is fabricated using NiCo 2 S 4 /GNS as positive electrode and nitrogen‐doped graphene as negative electrode. The fabricated ASC delivers a remarkable energy density of 54.6 Wh kg −1 at a power density of 350.8 W kg −1 . The outstanding performances render such composite a promising candidate for application of high‐energy‐density supercapacitors.