A flexible all-solid-state symmetric supercapacitor with 1.6 V high voltage window was designed by in situ growth of α-FeOOH based on carbon fiber yarn

Fibrous all-solid-state flexible supercapacitors have attracted much attention in the functional field of wearable electronic devices due to their excellent deformability. It is very important to select suitable flexible substrate, active substance, and binding means to improve electrode performance. In this paper, carbon fiber with high conductivity and the active site was used as a flexible substrate, and FeOOH with high specific capacity was grown on the surface of carbon fiber yarn by one-step in situ electrodeposition. The influence of different deposition conditions on the morphology of FeOOH and the electrochemical performance of the flexible electrode was studied. The electrode obtained by deposition at a constant voltage of 2.5 V for 150 min has a high specific capacitance of 10.44 F cm −3 . In addition, the device has a high voltage window of 1.6 V and excellent cycle stability of 7000 cycles when formed as an all-solid-state symmetric supercapacitor.