Uniquely Designed Tungsten Oxide Nanopetal Decorated Electropsun PAN Nanofiber for a Flexible Supercapacitor with Ultrahigh Rate Capability and Cyclability

A supercapacitor electrode material with unique morphology, i.e., tungsten oxide nanopetal decorated electrospun polyacrylonitrile (PAN) nanofibers, was synthesized. In this study, a polymeric solution of PAN was electrospun to form uniform high aspect ratio cross-linked nanofibers with diameter ∼400–500 nm that were further decorated with tungsten oxide nanopetals with a particle size around 30–40 nm through a hydrothermal treatment. The supercapacitor device fabricated using the as-synthesized material (W-PAN) coated carbon cloth as the working electrode exhibited a very high specific capacitance of 1107 F g–1 at a scan rate of 1 mV s–1. It was capable of performing with 100% capacitance retention at least up to 1000 cycles at a very high current density of 40 A g–1, suggesting ultrahigh rate capability and cyclability of the crafted electrode. Moreover, the charge storage mechanism was investigated which provided intriguing insights about the capacity contribution from tungsten oxide and PAN fibers to the overall capacitance. The W-PAN sample was capable of delivering a maximum energy density (Ed) of 33.33 W h kg–1 at a power density (Pd) of 2317 W kg–1 in half-cell configuration. The symmetric device fabricated using the composites, besides possessing an optimal voltage of 1.1 V, was also capable of delivering an energy density value of 641.66 mW h kg–1 at a power density of 16.47 W kg–1. The device also exhibits excellent cycle stability with a capacitance retention of 100% even after 2000 cycles. The physiochemical characterizations imparted comprehensive insight toward the interaction between the functional moieties present on the PAN fibrous matrix with tungsten oxide.