Hierarchical core-shell polypyrrole@NiCo layered double hydroxide arrays grown on stainless steel yarn with high flexibility for 1D symmetric yarn-shaped supercapacitors

Abstract

A great deal of attention has been paid to flexible energy storage devices in recent years, but it remains a challenge to obtain integratable 1D energy storage devices with high specific capacitance and mechanical flexibility that can operate normally under common extrusion, bending, and tensile deformations. Herein, a flexible 1D yarn-shaped supercapacitor (YSC) was constructed based on Polypyrrole (PPy) @NiCo-layered double hydroxide (LDH) @stainless steel yarn (SSY) electrode prepared by facile hydrothermal and electrochemical deposition method. The as-obtained PPy@NiCo-LDH@SSY electrode exhibited an enhanced specific capacitance of 1196 F g−1 at 1 A g−1, owing to the synergistic impact of electroactive materials as well as the stratified core-shell structure. The electrospun separator automatically ensured the regular operation of the YSC device throughout use. Moreover, the YSC exhibited an energy density of 6.6 mWh cm−3 at the power density of 159.2 mW cm−3 and outstanding cycle performance (about 85.7% after 10 000 cycles). In addition, the YSC still maintained high electrochemical performance under different bending angles. The low cost, excellent overall performance and scalability make YSC a promising flexible wearable energy storage device.