Electrodes Based on Se Anchored on NiCoP and Carbon Nanofibers for Flexible Energy Storage Devices

In an energy storage device, it is indeed a necessity to develop a flexible binder-free electrode. However, the rational design of such a binder-free electrode with high energy density and long cyclic stability is a great challenge for the scientific community. Herein, Se-anchored NiCoP nanoparticles have been developed that are in situ decorated on the surface of polyacrylonitrile-based heat-treated flexible carbon nanofibers (CNFs). The as-designed electrode demonstrates a remarkable specific capacitance/capacity of 994 F g–1/497 mAh g–1 at 1 A g–1. The flexible solid-state symmetric supercapacitor (SSC) device delivers 76.86 Wh kg–1 energy density at a power density of 843.75 W kg–1 at 0.75 A g–1 and retains a promising energy density of 22.75 Wh kg–1 at an ultrahigh power density of 11250 W kg–1 at 10 A g–1, respectively. The device also shows excellent long cyclic stability in terms of 94.12% capacitive retention along with 98.65% Coulombic efficiency after 15000 cycles at an applied high current density of 10 A g–1. The synergetic effect of Se-anchored NiCoP with CNF along with the significant protection of NiCoP by a thin graphitic shell as well as suitable anchoring of electroactive materials on a CNF matrix via Se bridging may help to achieve such a high-performance energy storage device. The four sets of 1 × 1 cm2 prototype devices (connected in series) are capable of enlightening a red-light-emitting diode (2.2 V) for 8 min and rotating a 3 V electric direct-current motor for 4 min via charging through a standard Si solar panel (6 V) illuminated by a 50 W street light for 2 min. The study creates an avenue toward the realistic drive of renewable energy conversion via the development of a high-performance flexible energy storage device.