Novel pseudocapacitive one-dimensional copper pyrophosphate (Cu2P2O7) nanofibers for asymmetric supercapacitor

The redox activity of a supercapacitor electrode can be significantly compromised by irregular, non-uniform, and agglomerated morphologies of the material. The preparation of a one-dimensional fibrous morphology not only ensures a consistent, continuous, and well-separated network of fibers but also results in an increased surface area compared to higher-dimensional structures. In this study, the fabrication of a continuous network of one-dimensional copper pyrophosphate (Cu₂P₂O₇) nanofibers through a straightforward polymer-based electrospinning method followed by calcination at 900 °C is reported. The resulting Cu₂P₂O₇ monoclinic nanofibers exhibited an average diameter of 95 nm, highlighting the enhanced surface area of the material. By employing nickel foam (NF) as a current collector, the Cu₂P₂O₇/NF electrode demonstrated a remarkable specific capacitance of 567.31 F g^-1 (357.4 C g^-1) at 2 A g^-1 in 1 M LiOH electrolyte, surpassing performances in 1 M KOH and 1 M NaOH electrolytes. Furthermore, we designed an asymmetric supercapacitor (ASC) device configuration by incorporating carbon nanofibers (CNFs) as the negative electrode. Cu₂P₂O₇//CNFs asymmetric supercapacitor showcases an exceptional specific capacitance, reaching 143.73 F g^-1 (244.34 C g^-1) at a current density of 0.4 A g^-1. This remarkable performance is complemented by a notable energy density of 57.69 Wh kg^-1 and power density of 1104.7 W kg^-1. Furthermore, even at an elevated power density of 5132.25 W kg^-1, the device maintained a considerable energy density of 22.81 Wh kg^-1. These findings underscore the viability of Cu₂P₂O₇ nanofibers as a compelling choice for energy storage devices.