Nitrogen doped carbon nanofibers(NCNF)are prepared by electrospinning method and high-temperature carbonization methods,and nickel cobalt layered double hydroxide(NiCo LDH)nanosheets are in-situ grown on the surface of NCNF through hydrothermal synthesis reaction to produce NiCo LDH/NCNF composite with core-shell structure.The morphology and structure of NiCo LDH/NCNF composite are demonstrated,and the electrochemical properties of composite are tested.The results show that the specific capacitance can reach 2 822.9 F/g at 1 A/g,and still reach 2 178.8 F/g at 10 A/g,and the capacitance retention rate is as high as 77.2％,demonstrating excellent rate performance.After 6000 charge-discharge cycles,the capacitance retention is 91.8％,indicating excellent cycle stability performance.An asymmetric supercapacitor(ASC)assembled using NiCo LDH/NCNF as the positive electrode and activated carbon(AC)as the negative electrode has a specific capacitance of 226.1 F/g at 1 A/g,a high energy density of up to 69.2 Wh/kg with a power density of 742.1 W/kg.Therefore,the NiCo LDH/NCNF composite could be as promising electrode materials for energy conversion and storage.
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