Electrochemical properties of ACNF/Li2FeSiO4 composite nanostructures for supercapacitors

This work reports the synthesis and electrochemical properties of activated carbon nanofibers (ACNF) composited with Li2FeSiO4 for supercapacitors. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller analyzer (BET), transmission electron microscopy (TEM), and thermal gravimetric analyzer (TGA). The electrochemical properties were tested using a variety of techniques, such as cyclic voltammetry (CV), galvanostatic charge-discharge (GDC), and electrochemical impedance spectroscopy (EIS). The structural transformation during charging and discharging processes was studied by in-situ time resolved X-ray absorption spectroscopy (in-situ TRXAS). The ACNF/Li2FeSiO4 presented monoclinic structure with space group of P21/n, although there was a small impurity of FeO. The structural transformations of iron upon cycling in the + 2 to + 3 state were responsible for high capacity of ACNF/Li2FeSiO4 materials. The maximum specific capacitance of 158 Fg-1 at 2 mVs-1 and 201 Fg-1 at 0.25 Ag-1 with the corresponding specific energy of 17.8 Whkg-1 and specific power of 99.7 Wkg-1 were observed. Moreover, this composite material exhibited an excellent cycle performance through maintaining over 85% of its initial capacitance after 1000 cycles. The interesting electrochemical properties of ACNF/Li2FeSiO4 composite nanostructure make it a potential candidate for supercapacitors. (c) 2022 Elsevier B.V. All rights reserved.