Flexible Wire-Shaped Supercapacitors in Parallel Double Helix Configuration with Stable Electrochemical Properties Under Static/Dynamic Bending

Abstract

Wire-shaped flexible supercapacitors (SCs) have aroused much attention due to their small size, light weight, high flexibility and deformability. However, the previously reported wire-shaped SCs usually involve complex assembly process and encounter potential structural instability, and the influence of dynamic bending on the electrochemical stability of wire-shaped SCs is also not clear. Here, a parallel double helix wire-shaped supercapacitor (PDWS) protocol has been developed with two symmetric titanium@MnO2 fiber electrodes winded on a flexible nylon fiber by a simple and reliable process. The PDWSs show an operate voltage of 0.8 V, a high capacitance of 15.6 mF cm-2 and an energy density of 1.4 μWh cm-2. Due to rational structure design, the PDWSs demonstrate excellent mechanical and electrochemical stability under both static and dynamic deformations. Over 3500 bending cycles, 88.0% of the initial capacitance can still be retained. In terms of dynamic bending, it is found that the cyclic voltammetry curves show periodically fluctuations simultaneously with the bending frequency and the intensity of fluctuation increases with higher bending frequency, while the dynamic capacitance is almost not affected. With extraordinary mechanical flexibility and excellent electrochemical stability, the high performance PDWS is considered to be a promising power source for wearable electronics. Figure 1