Electrospun nickel cobalt phosphide/carbon nanofibers as high-performance electrodes for supercapacitors

Nickel cobalt phosphide/carbon nanofibers (NiCoP/C) with an average diameter of approximate 200 nm are prepared by electrospinning combined with calcinations. Carbon nanofibers with an average pore size of 10.77 nm as conductive skeletons support the dispersed NiCoP nanoparticles with the size ranging from 20 to 80 nm, providing abundant reactive sites and facilitating the electrochemical reactions. The specific capacitance of NiCoP/C reaches 478 F g-1 at 2 A g-1 in a 3 M KOH electrolyte, showing superior electrochemical properties compared to its counterparts. After 5000 charge/discharge cycles at 10 A g-1, 99.99 % of initial specific capacitance is retained. In addition, an asymmetric supercapacitor assembled using NiCoP/C as positive electrode and activated carbon as negative electrode exhibits an energy density of 16.72 Wh kg-1 at a high-power density of 7250 W kg-1. Furthermore, the capacitance loss of the supercapacitor is only 0.04 % after 5000 cycles at 10 A g-1, which is mainly attributed to the enhanced stability of NiCoP nanoparticles owing to the assistance of carbon nanofibers as the skeleton. The synergistic effects of NiCoP nanoparticles and carbon nanofibers result in the boosted electrochemical performances. This study demonstrates the potential application of carbon nanofibers as conductive skeletons for nanostructured electrodes.