Iron oxides nanobelt arrays rooted in nanoporous surface of carbon tube textile as stretchable and robust electrodes for flexible supercapacitors with ultrahigh areal energy density and remarkable cycling-stability

We report a significant advance toward the rational design and fabrication of stretchable and robust flexible electrodes with favorable hierarchical architectures constructed by homogeneously distributed α -Fe 2 O 3 nanobelt arrays rooted in the surface layer of nanoporous carbon tube textile (NPCTT). New insight into alkali activation assisted surface etching of carbon and in-situ catalytic anisotropic growth is proposed, and is experimentally demonstrated by the synthesis of the Fe 2 O 3 nanobelt arrays/NPCTT. The Fe 2 O 3 /NPCTT electrode shows excellent flexibility and great stretchability, especially has a high specific areal capacitance of 1846 mF cm −2 at 1 mA cm −2 and cycling stability with only 4.8% capacitance loss over 10,000 cycles at a high current density of 20 mA cm −2 . A symmetric solid-state supercapacitor with the Fe 2 O 3 /NPCTT achieves an operating voltage of 1.75 V and a ultrahigh areal energy density of 176 µWh cm −2 (at power density of 748 µW cm −2 ), remarkable cycling stability, and outstanding reliability with no capacity degradation under repeated large-angle twisting. Such unique architecture improves both mechanical robustness and electrical conductivity, and allows a strong synergistic attribution of Fe 2 O 3 and NPCTT. The synthetic method can be extended to other composites such as MnO nanosheet arrays/NPCTT and Co 3 O 4 nanowire arrays/NPCTT. This work opens up a new pathway to the design of high-performance devices for wearable electronics.