Conductive Ni2P nanosheet arrays-carbon nanofibers as binder-free pseudocapacitive electrode materials

Abstract

• The Ni 2 P-CNFs has high conductivity, ample active sites and good redox activity. • The Ni 2 P-CNFs is a flexible material that can directly use as self-supported supercapacitor electrode materials without the binders. • The Ni 2 P-CNFs electrode materials exhibited excellent specific capacitance of 1057.5 F g −1 at the current density of 0.5 A g −1 , good rate capability and prominent cycle stability. • The Ni 2 P-CNFs//CNF asymmetric supercapacitor displayed the energy density of 8.5 Wh kg −1 at the power density of 353.3 W kg −1 . Flexible carbon nanofibers (CNFs) were prepared by electrospinning of polyacrylonitrile, followed by peroxidation and carbonization treatments. Then, conductive Ni 2 P nanosheet arrays were vertically grown on the CNFs by phosphorizating of Ni-precursor on its surface. The obtained CNFs loaded by conductive Ni 2 P nanosheet arrays (Ni 2 P-CNFs) were directly used as flexible pseudocapacitive electrode materials. Results showed that the Ni 2 P-CNFs electrode displayed remarkable specific capacitance of 1057.5 F g −1 at 0.5 A g −1 , good rate capability of 387.5 F g −1 at 50 A g −1 and prominent capacitance retention of 89.7% after 3000 cycles at 5 A g −1 . Asymmetric supercapacitor based on Ni 2 P-CNFs and CNFs were fabricated, which showed energy density of 8.5 Wh kg −1 at power density of 353.3 W kg −1 and the capacitance was kept at 92.5% after 3000 cycles at 2 A g −1 . Therefore, the conductive Ni 2 P-CNFs would be a promising pseudocapacitive electrode materials for asymmetric supercapacitor.