Uniform and fully decorated novel Li-doped α-Fe2O3 nanoparticles for high performance supercapacitors

Abstract

Supercapacitors are considered emerging energy storage sources owing to their long-term cycling stability, high energy/power density, and rapid charge/discharge process. The performance characteristics of supercapacitors can be enhanced by devising electrodes with highly porous nanostructures through subtle hybridization of active materials and the development of current collectors with tailored nanoarchitectures. Herein, we reported the effect of Li doping on the electrochemical application of the pure α-Fe2O3 thin films. The preparation of nanoparticles-like nanostructures of the pure α-Fe2O3 and different percentages of Li-doped α-Fe2O3 thin films by cost effective and facile hydrothermal method for the supercapacitor application. As-synthesized pure α-Fe2O3 and Li doped α-Fe2O3 thin films were analyzed by the X-ray diffraction (XRD), and X-ray photoelectron (XPS) spectroscopy, scanning electron microscopy, transmission electron microscopy, and supercapacitor properties. The XRD results revealed the formation of the pure phase of the α-Fe2O3 with the rhombohedral crystal structure. XPS results confirmed the Li species existence in the 0.5% Li doped α-Fe2O3. The electrochemical properties indicate the 3D chain of the nanoparticle-like surface morphology of pure α-Fe2O3 and Li-doped α-Fe2O3 are more useful electrode materials for electrochemical application. The calculated values of the specific capacity (Cs) indicate the different percentages of doping of Li are affected by the electrochemical properties of the pure α-Fe2O3. The Cs of the optimized 0.5% Li-doped α-Fe2O3 (79 mAh g−1) electrode was 1.3-fold higher than that of the pure α-Fe2O3 electrode (52 mAh g−1) at a constant scan rate with excellent cycling stability upto 3000 cycles. The electrochemical and surface morphological analysis demonstrate that the 0.5% Li-doped α-Fe2O3 electrode is more useful than the pure α-Fe2O3 and other electrodes for developing high-rate hybrid supercapacitor-based energy storage devices applications.