Ultrahigh energy fiber-shaped supercapacitors based on porous hollow conductive polymer composite fiber electrodes

Fiber-shaped supercapacitors (FSCs) that exhibit high electrochemical performance while maintaining mechanical reliability are urgently needed to meet the growing demand for wearable electronics. However, developing fiber electrodes with nanoporous microstructures remains challenging. Here, we proposed high-energy, ultra-stable FSC devices based on a new class of porous, hollow, and conductive composite fibers (PHCFs) with a multilayer structure. The nanoporous structures of the PHCFs substantially increased both the specific surface area (98.1 m 2 g −1 ) and the pore volume (0.43 cm 3 g −1 ), but had a negligible influence on the mechanical properties. Such an interconnected nanoporous structure in the PHCFs guaranteed high mass loading and high efficiency utilization of electrodeposited PANI, and the derived fiber electrodes (PHCFs@PANI) delivered a high areal capacitance of 2723 mF cm −2 and unprecedented ultrastable cycle performance without any capacitance loss over 26 000 cycles. Furthermore, a symmetric FSC (S-FSC) device based on PHCFs@PANI achieved a remarkable energy density of 55.3 μW h cm −2 at a power density of 447 μW cm −2 , values far superior to those of most recently reported FSCs. Moreover, the S-FSC was able to withstand various deformations, such as repeated bending, twisting, and knotting, with a nearly invariant capacity.