A novel flexible dual-functional energy storage device with switchability based on NiCo2S4-x

Abstract

The demands for new energy storage systems capable of providing power for various wearable electronic devices are generating more research interest. Herein, we develop a universal and effective strategy to integrate Zn ion battery (ZIB) and asymmetric supercapacitor (ASC) into one flexible energy storage device, which can switch between high energy density and high-power density without interfering with each other. The NiCo2S4-x nanosheet arrays with sulfur deficiency grown on carbon cloth substrate are used as efficient cathode for ZIB and ASC. The designed flexible ZIB delivers an energy density of up to 464.2 Wh kg−1, while the assemble flexible ASC provides a maximum power density of 8001.2 W kg−1. Subsequently, a flexible dual-functional three-electrode energy storage device (TEESD) is fabricated by a general stacking strategy. As proof-of-concept demonstrations, two flexible dual-functional TEESDs can switch between ZIB and ASC to power a digital watch and light LED thanks to the common cathode. In addition, the integrated TEESDs exhibits superior electrochemical stability and performance durability, which is beneficial for the practical applications in flexible and wearable devices. The general strategy disclosed herein is expected to shine new light into the development of advanced flexible electronics and wearable energy textiles.