A novel inorganic-conductive polymer core-sheath nanowire arrays as bendable electrode for advanced electrochemical energy storage

Abstract Bendable asymmetric supercapacitor (BAS) has been considered to be excellent energy storage for the flexible device and the electrode materials involved in BAS may bring in high electrochemical performance are crucial for practical application. In this work, a novel heterogeneous NiCo 2 S 4 @polypyrrole core-sheath nanowire is directly grown on Ni foam (NiCo 2 S 4 @PPy-Ni foam) by hydrothermal and electrochemical methods. The unique electrode shows a remarkable areal special capacitance of 6.3 F cm −2 at 50 mA cm −2 and exceptional capacitance retention of 91.2% after 5000 cycles. Using NiCo 2 S 4 @PPy-Ni foam and AC-Ni foam (active carbon-Ni foam) as positive and negative electrodes, respectively, a BAS (NiCo 2 S 4 @PPy//AC-Ni foam) was fabricated. The resulting exhibits a wide potential window of 1.8 V and a high capacitance of 7.36 F cm −2 (1925 F g −1 ). As a result, the BAS shows a maximum energy of 86.6 Wh kg −1 at a power density of 1046 W kg −1 and a perfect stability after 8000 cycles at a current density of 1.0 A cm −2 . Furthermore, the BAS shows good flexibility and can withstand bending at 30–90 angles while keeping electrochemical performance constant. Such a BAS totally based on unique active materials and bendable Ni foam substrate which would be a promising candidate for using in wearable devices.