Electrospun ZnFe2O4/carbon nanofibers as high-rate supercapacitor electrodes

ZnFe2O4/carbon (ZFO/C) nanofibers are prepared by electrospinning method with subsequent stabilization treatment, high temperature carbonization, and extra induced annealing for high performance supercapacitor electrodes. Previous attempts to incorporate ZFO into electrospun fibers always resulted in ZFO nanofibers without carbon or multiphase components in carbon nanofibers. In this work, the extra induced annealing is introduced, successfully producing ZFO/C nanofibers without any other phases. The continuous carbon nanofibers with a diameter of ~180 nm could make the ion diffusion distance shorter, enhance the conductivity of ZFO, and improve the structural stability of the ZFO/C nanofibers, whereas the small ZFO nanoparticles (~30 nm) can be fully utilized during electrochemical reactions. Therefore, the optimized ZFO/C–B-250-600-280 exhibits a remarkable specific capacitance of 237 F g−1 at the current density of 1 A g−1. Even at the current density of 10 A g−1, 88.2% of capacity is retained.