Construction of tremella-like Co9S8@NiCo2S4 heterostructure nanosheets integrated electrode for high-performance hybrid supercapacitorsConceptualization, Methodology, Formal analysis

Transition metal sulfides (TMSs) have been widely researched as promising electrode materials for super capacitors because of their high theoretical capacitance and rich redox reactive sites. In this work, tremella-like core-shell Co9S8@NiCo2S4 heterogeneous nanosheets were directly grown on Nickel foamed (NF) through the hydrothermal+electrodeposition method to obtain a self-supporting electrode. Benefiting from its unique tremella-like structure, ultra-thin nanosheets, and the positive synergies between Co9S8 and NiCo2S4, the prepared Co9S8@NiCo2S4@NF electrode presents a high specific capacity of 513 C g(-1) (specific capacitance similar to 1026 F g(-1)) at 1 A g(-1) with superior rate capability (62.8% capacitance retention rate at 10 A g(-1)). Furthermore, the fabricated Co9S8@NiCo2S4@NF//active carbon (AC) hybrid supercapacitor displays a high energy density of 30 Wh kg(-1) at a power density of 731.8 W kg(-1) and superior cycling stability. The results prove that the strategy of hydrothermal+electrodeposition is a very effective method for the preparation of energy storage and conversion materials with unique core-shell morphology. (C) 2021 Elsevier B.V. All rights reserved.