Three-Dimensional NiCo₂O₄@Polypyrrole Coaxial Nanowire Arrays on Carbon Textiles for High-Performance Flexible Asymmetric Solid-State Supercapacitor

In this article, we report a novel electrode of NiCo₂O₄ nanowire arrays (NWAs) on carbon textiles with a polypyrrole (PPy) nanosphere shell layer to enhance the pseudocapacitive performance. The merits of highly conductive PPy and short ion transport channels in ordered NiCo₂O₄ mesoporous nanowire arrays together with the synergistic effect between NiCo₂O₄ and PPy result in a high specific capacitance of 2244 F g^–1, excellent rate capability, and cycling stability in NiCo₂O₄/PPy electrode. Moreover, a lightweight and flexible asymmetric supercapacitor (ASC) device is successfully assembled using the hybrid NiCo₂O₄@PPy NWAs and activated carbon (AC) as electrodes, achieving high energy density (58.8 W h kg^–1 at 365 W kg^–1), outstanding power density (10.2 kW kg^–1 at 28.4 W h kg^–1) and excellent cycling stability (∼89.2% retention after 5000 cycles), as well as high flexibility. The three-dimensional coaxial architecture design opens up new opportunities to fabricate a high-performance flexible supercapacitor for future portable and wearable electronic devices