Nanoporous electrospun NiCo2S4 embedded in carbon fiber as an excellent electrode for high-rate supercapacitors

The intertwined fiber structure is advantageous as a structure of supercapacitor electrode material. In this paper, the NiCo2S4 embedded in carbon fiber (NiCo2S4/CF) has been prepared through hydrothermal vulcanization of electrospun NiCo2O4/carbon nanofibers precursor. It is a simple way to integrate the pseudocapacitive material with carbon, rendering high capacitance (1169 F g(-1) at 1 A g(-1)), excellent rate capability (81.3% at 20 A g(-1)) and superior cycle stability (87.2% capacitance retention after 10,000 cycles). Afterwards, an all-solid-state asymmetric supercapacitor device (ASC) has been prepared with the NiCo2S4/CF positive electrode and porous carbon nanofiber negative electrode. When the power density of ASC is 878.3 W kg(-1), the energy density can reach 28.8 Wh kg(-1) with excellent cycle stability.