Co-Axial Fabrication of Ni-Co Layered Double Hydroxide into 3d Carbon Nanotube Networks for High-Performance Flexible Fiber Supercapacitors

Despite the advantages of fiber-shaped supercapacitors (FSCs) in powering wearable electronics, the low energy density dramatically hinders their practical application. Asymmetric configuration design especially with pseudocapacitive materials is an effective solution due to the extended voltage window and large pseudocapacitance. Herein, we design a flexible, asymmetric FSC consisting of carbon fiber (CF) as substrate, multiple and alternate Ni-Co layered double hydroxide/mono-dispersed carbon nanotube (CNT) co-axial layers ([Ni-Co LDH-x/CNT-y]@CF) as the positive electrode materials and tremella-derived activated carbon@CF (TDC- z @CF) as negative electrode material. The 3D Ni-Co LDH/mono-dispersed CNT networks enable high mass loading of active materials, fast electron transfer, efficient ion diffusion, and mechanical stress release. The TDC- z possesses large surface areas with hierarchical porous structures, thus demonstrating high capacitive performance. Based on that, the resulting FSC achieves a remarkable energy density of 26.20 Wh kg -1 , a power density of 7569.23 W kg -1 , and superior cycling stability of 97.6% over 5000 cycles at a current density of 5 A g −1 . Several supercapacitors connected in series can also drive a portable LED device for over 10 minutes. Furthermore, the assembled device also exhibits excellent mechanical stability under various deformation conditions. These appealing properties make our FSCs an attractive candidate in powering wearable and flexible electronic devices