Electrostatically assembled nanoflower-like MXene/NiCu-layered double hydroxide composite thin-film: A high capacitive energy storage for flexible supercapacitors

Advancements in wearable electronic devices, including electronic skins, flexible displays, and soft robots have driven the development of high-performance flexible supercapacitors (SC). MXene, one of the most promising energy storage materials, has attracted widespread attention due to its unique two-dimensional structure, high electrical conductivity, and rich surface functional groups. However, nanosheet restacking limits the improvement in the capacitance performance of MXene films. This study develops a novel approach to self-assemble MXene and NiCu-layered double hydroxide composite films, which significantly enhance the electrochemical performance of the MXene films, mitigating the inherent aggregation and enhancing the capacitance. The composite exhibits a mass-specific capacitance of 556.4 F g⁻¹ at a current density of 1 A g⁻¹. Moreover, at a current density of 1 A g⁻¹, the study demonstrates an energy density of 12.4 Wh kg⁻¹ and a power density of 500 W kg⁻¹ when the composite with TNC-2 is used as both positive and negative electrodes. The capacitance retention rate remains at 90 % after 5,000 cycles at 10 A g⁻¹, indicating excellent long-term performance. This study provides new insights into the development of self-supporting flexible thin-film electrodes for high-performance SC devices.