NiCo2S4 Nanotubes Anchored 3D Nitrogen-Doped Graphene Framework as Electrode Material with Enhanced Performance for Asymmetric Supercapacitors

NiCo2S4 is considered as a promising candidate for high-performance supercapacitors as it stores energy through fast surface redox reactions. However, it suffers from severe aggregation which deteriorates their stability. Herein, uniformly distributed NiCo2S4 nanotubes anchored on a 3D ultrathin nitrogen (N)-doped graphene framework (NGF) are obtained via a facile hydrothermal method, followed by a sulfurization process. The NGF composed of conductive three-dimensional graphene scaffolds can not only ensure even distribution of NiCo2S4 but also facilitate electron transport. Meanwhile, NiCo2S4 nanotubes with hollow structures can shorten the diffusion pathway of electrolyte ions. The strong synergistic effect between NiCo2S4 nano tubes and the NGF substrate helps to obtain satisfactory electrochemical properties. Accordingly, the as-prepared NiCo2S4/NGF composite exhibits a specific capacitance of 1240 F g(-1) (558 C g(-1)) at 1 A g(-1), almost 2-fold of its counterpart NiCo2S4 (688.9 F g(-1)/310 C g(-1)). Moreover, the corresponding hybrid energy device (NiCo2S4/NGF\ \AC) demonstrates a superb energy density of 36.8 Wh kg(-1) and outstanding cycling stability. This admirable design of the NiCo2S4/NGF composite holds great promise as an electrode material in supercapacitor application.