Tungsten Oxide@Polypyrrole Core–Shell Nanowire Arrays as Novel Negative Electrodes for Asymmetric Supercapacitors

Among active pseudocapacitive materials, polypyrrole (PPy) is a promising electrode material in electrochemical capacitors. PPy‐based materials research has thus far focused on its electrochemical performance as a positive electrode rather than as a negative electrode for asymmetric supercapacitors (ASCs). Here high‐performance electrochemical supercapacitors are designed with tungsten oxide@PPy (WO₃@PPy) core–shell nanowire arrays and Co(OH)₂ nanowires grown on carbon fibers. The WO₃@PPy core–shell nanowire electrode exhibits a high capacitance (253 mF/cm²) in negative potentials (–1.0–0.0 V). The ASCs packaged with CF‐Co(OH)₂ as a positive electrode and CF‐WO₃@PPy as a negative electrode display a high volumetric capacitance up to 2.865 F/cm³ based on volume of the device, an energy density of 1.02 mWh/cm³, and very good stability performance. These findings promote the application of PPy‐based nanostructures as advanced negative electrodes for ASCs.