Construction of NiCo 2 O 4 nanoflake arrays on cellulose-derived carbon nanofibers as a freestanding electrode for high-performance supercapacitors

Cellulose has a wide range of applications in many fields due to their naturally degradable and low-cost characteristics, but few studies can achieve cellulose-nanofibers by conventional electrospinning. Herein, we demonstrate that the freestanding cellulose-based carbon nanofibers are successfully obtained by a special design of electrospinning firstly, pre-oxidation and high-temperature carbonization (1600 °C), which display a superior electrical conductivity of 31.2 S·cm −1 and larger specific surface area of 35.61 m 2 ·g −1 than that of the polyacrylonitrile-based carbon nanofibers (electrical conductivity of 18.5 S·cm −1 , specific surface area of 12 m 2 ·g −1 ). The NiCo 2 O 4 nanoflake arrays are grown uniformly on the cellulose-based carbon nanofibers successfully by a facile one-step solvothermal and calcination method. The asprepared cellulose-based carbon nanofibers/NiCo 2 O 4 nanoflake arrays are directly used as electrodes to achieve a high specific capacitance of 1010 F·g −1 at 1 A·g −1 and a good cycling stability with 90.84% capacitance retention after 3000 times at 10 A·g −1 . Furthermore, the all-solid-state symmetric supercapacitors assembled from the cellulose-based carbon nanofibers/NiCo 2 O 4 deliver a high energy density of 62 W·h·kg −1 at a power density of 1200 W·kg −1 . Six all-solid-state symmetric supercapacitors in series can also power a ‘DHU’ logo consisted of 36 light emitting diodes, confirming that the cellulose-based carbon nanofiber is a promising carbon matrix material for energy storage devices.