Design of high-performance core-shell hollow carbon nanofiber@nickel-cobalt double hydroxide composites for supercapacitive energy storage

the supercapacitive performances of supercapacitor mainly depend on the physical nanostructure and micro-morphology of electrode materials. here, we demonstrated the design, synthesis and electrochemical performances of core-shell hollow carbon nanofiber@nickel-cobalt-layered double hydroxide (hcnf@ ni0.67co0.33-ldh) nanocomposites with an optimized ni/co molar ratio of 2:1. the hcnf was used as superiorly conductive core to sustain the nanoporous silky ni0.67co0.33-ldh shell, which can efficiently provide fast transport pathways for electrons and electrolyte ions. the outstanding specific capacitance of 2486 f g−1 at 1 a g−1 based on galvanostatic charge-discharge curves were acquired for the highly electroactive hcnf@ni0.67co0.33-ldh. furthermore, the hcnf@ni0.67co0.33-ldh electrode delivered a distinguished rate capability with a specific capacitance of 1890 f g−1 even at 15 a g−1. notably, an asymmetric supercapacitor with hcnf@ni0.67co0.33-ldh as cathode and hcnf as anode was devised, which presented a prominent specific capacitance of 228 f g−1, good energy density of 62.1 wh kg−1, and impressive cycling stability (90.6% capacitance retention after 10,000 cycles).