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

Abstract

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).