Polyaniline nanowires anchored on MXene quantum dots/graphene composite fibers with 0D-1D-2D hierarchical structure for high-performance wearable supercapacitors

Two-dimensional graphene and MXene are promising and attractive candidates as energy storage materials for wearable supercapacitors. However, low energy density derived from a serious restacking problem restricts their charge storage capacity and actual application for portable electronic devices. In this study, we report a microfluidic technique assisted wet spinning method for the fabrication of polyaniline nanowires modified MXene quantum dots/graphene composite fibers (PANI@MQDs/GF) with 0–1-2 dimensional (0D-1D-2D) hierarchical structure. The effective combination of multicomponents, strong synergistic effect at the nanoscales and 0D-1D-2D hierarchical structure of PANI@MQDs/GFs not only alleviate the restacking of graphene nanosheets but also enhance interfacial charge transfer, more accessible sites and fast pathways for ion kinetic migration and accumulation, leading to excellent structural stability and electrochemical performance. Fiber-based flexible supercapacitors assembled by PANI@MQDs/GF exhibit a superior specific areal capacitance of 1691 mF cm⁻² (for specific volumetric capacitance of 450 F cm⁻³), maintain a high capacitance retention of nearly 100 % after 9500 cycles, and achieve an excellent energy density of 214.4 μWh cm⁻². The designed 0D-1D-2D hierarchical structure of composite fibers can also be extended to other lamellar materials, and exploit more possibilities of fiber-typed supercapacitors for portable/wearable electronics application.