Hierarchical structure of Self-Supported NiCo2S4 Nanoflowers@NiCo2S4 nanosheets as high rate-capability and cycling-stability electrodes for advanced supercapacitor

Abstract Hierarchical nanostructure of materials can protect themselves from damage and improve the stability in electrochemical reaction as electrode materials, increasing active sites and ion adsorption, and then strengthen the electrochemical performance for supercapacitors. In this work, hierarchical NiCo2S4 nanoflowers@NiCo2S4 nanosheets (NiCo2S4 NFs@NiCo2S4 NSs) composite was fabricated on Ni foam substrate via facile and low-cost multistep hydrothermal methods. As a result, the NiCo2S4 NFs@NiCo2S4 NSs with unique hierarchical nanostructure demonstrates prominent rate property with the capacity of 338.1 mAh/g at 1 A/g and 290.1 mAh/g at 10 A/g. In addition, the cycling stability of the NiCo2S4 NFs@NiCo2S4 NSs is enhanced significantly (capacitance loss of 8% after 4000 cycles) on account of distinct and stable microarchitecture. Furthermore, the assembled NiCo2S4 NFs@NiCo2S4 NSs//NiCo2S4 NFs@NiCo2S4NSs symmetrical supercapacitor (SSC) device proves a favorable power density of 750 W/kg at energy density of 18.04 Wh/kg with cycling stability of 89% after 4000 charge/discharge cycles. This strategy is offered to generate the unique and low-cost hierarchical electrode structure leading excellent electrochemical properties and demonstrating its application prospect as electrode material.