Construction of CNT/CuS/FeOOH hierarchical composites on carbon cloth for high-performance solid-state flexible supercapacitors

Flexible supercapacitors (FSC) are ideal energy storage devices for wearable electronic products, yet longstanding constrained by the limited performance of negative materials. Rational design of multiple-component nanocomposites with hierarchical structures is an effective strategy to enhance the energy storage capacity. In this study, a high-capacitance flexible electrode was constructed through the in-situ growth of copper sulfide (CuS) nanosheets on carbon nanotubes (CNT) decorated carbon cloth (CC), followed by the electrodeposition of ferric hydroxide (FeOOH). The negative electrode (CC/CNT/CuS/FeOOH) demonstrates an exceptional areal capacitance of 1956.1 mF cm−2 at 1 mA cm−2 and excellent cycle stability. Subsequently, a corresponding FSC device was constructed by incorporating NiCo layered double hydroxide (CC/CNT/NiCo-LDH) as the positive material and KOH/polyvinyl alcohol (PVA) gel as the electrolyte. The FSC device exhibits an impressive volumetric energy density of 3.3 Wh cm−3 under the power density of 12.2 W cm−3. It also demonstrates excellent electrochemical and mechanical stability, showcasing high capacitance retention under cyclic use and bending conditions. This work presents a rational design strategy for the development of cost-effective, high-capacitance and stable flexible electrodes, which holds promising for integration into wearable electronic devices.