Assembling zinc cobalt hydroxide/ternary sulfides heterostructure and iron oxide nanorods on three-dimensional hollow porous carbon nanofiber as high energy density hybrid supercapacitor

Abstract

The critical challenge of supercapacitors lies in sluggish kinetics of electrodes and undesirable specific capacitance during charge discharge process including large volume change and inferior cyclic stability. In this work an elaborately designed three dimensional hierarchical heterostructure comprising ternary metal sulfides completely covered by nickel cobalt layered double hydroxide (NiCo-LDH@ZNCS) core shell arrays on electrospun three-dimensional hollow porous carbon nanofiber and used as free-standing electrode material for supercapacitors. The original built-in interfacial potential between NiCo-LDH and ZNCS on conducting three dimensional hollow PCF can acquire multidimensional channels for ion/electron transfer and validate to be a highly capacitive cathode material with a high specific capacity of 407.11 mA h g−1 at the current density of 1 mA cm−2 maintaining outstanding rate performance. The iron oxide nanorods (Fe2O3-PCF) anode (216.15 mA h g−1 at the current density of 1 mA cm−2) match well to the cathode. Benefiting from the powerful synergistic effect, the assembled quasi solid state asymmetric supercapacitor can deliver ultrahigh energy density of 111.72 W h kg−1 at a power density of 243 W kg−1 and extra ordinary life cycle stability (95.2 % capacity retention after 20,000 charge discharge cycles). Such superior electrochemical performances are attributed to the multidimensional nanostructures, porous carbon networks, improved conductivity, and synergistic interaction between the active components of NiCo-LDH/ZNCS arrays. This approach provides a new perspective for rational design of high energy density hybrid supercapacitors, holding unbounded possibilities in this energy dependent world.