Lithium-ion doped NiFe2O4/SiO2 nanocomposite aerogel for advanced energy storage devices

Abstract Acid and base mediated sol–gel process followed by supercritical extraction of ethanol used for the synthesis of lithium-ion doped nickel ferrite loaded silica composite aerogels using a high-temperature high-pressure autoclave. The physical-chemical properties of synthesized materials are characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and DC-conductivity measurements. The conductivity results suggest that maximum electrical conductivity of 8.63 × 10 −9  Scm −1 is obtained for 4% Li 2 O doped 96%{10% NiFe 2 O 4  + 90% SiO 2 } composite aerogel due to Li + migration between grain-grain interface and electron hopping between Fe 2+ and Fe 3+ . Further, the XRD result also confirms the formation of amorphous SiO 2 , Li 2 O with crystalline NiFe 2 O 4 composite aerogel. FTIR results confirm the bond formation through molecular vibration between Si-O-Si and Ni 2+ /Fe 3+ -O. FESEM micrographs reflect the three-dimensional, highly porous interconnected network formation of 4LNS composite aerogel. Aqueous supercapacitor performance of Li 2 O doped NiFe 2 O 4 –SiO 2 composite aerogels were examined in 1 molar CH 3 COONa, Na 2 SO 4 and NaOH electrolytes on respective potential regions of 0.5 to −1 V, 0.4 to −0.8 V and 0 to −1.0 V using three electrode systems. The Li 2 O addition improves the conductivity and hence improve the specific capacitance of SiO 2 and NiFe 2 O 4 –SiO 2 composite aerogels synergically within the potential window.