Designing heterostructured metal sulfide core-shell nanoneedle films as battery-type electrodes for hybrid supercapacitors

Abstract Flexible high-performance electrochemical capacitors have aroused much attention with their prospect applications in future wearable electronic devices. Metal sulfide electrodes, which can meet the need of new energy materials, are one of the most representative candidates in energy devices. Here, a universal method is developed to in-situ grow a series of battery-type metal sulfide core-shell nanoneedle films (i.e., Co9S8-MoS2, Co9S8-NiS2, Co9S8-NiCo2S4, NiCo2S4-CuS, NiCo2S4-NiS2, and NiCo2S4-MoS2) on carbon cloth. When served as active materials in electrochemical tests, the Co9S8-NiCo2S4 electrode shows superior energy storage ability with a specific capacity of 337.78 mAh g-1 at 1 A g-1 and a retention rate of 93% undergoing 5000 cycles at 10 A g-1. Subsequently, the Co9S8-NiCo2S4 electrode is assembled into a flexible all-solid-state hybrid supercapacitor, which delivers a maximum specific energy of 56.44 W h kg-1 at 795 W kg-1 and a maximum specific power of 8153 W kg-1 at 29.44 W h kg-1. Finally, such hybrid metal sulfide-based device can be made into wearable chargers to drive a low-power electronic device. This study provides a facile strategy to rationally prepare a variety of heterostructured metal sulfide films and then effectively select high-performance electrodes for energy storage devices.