High specific surface area (2840.3 m²/g) in activated carbon/SnFe₂O₄ spinel nanocomposite: structural, optical, dielectric, and magnetic properties for Li-ion battery soft and porous electrode applications

This study focused on synthesis and characterization of super activated carbon/SnFe₂O₄ spinel nanocomposite as Li ion-battery soft electrode with high surface area. Various characterizations such as X-rays diffraction (XRD), UV–Vis spectroscopy, field emission electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), BET porosimeter analysis, vibrational sample magnetometry (VSM), and cyclic voltammetry (CV) were used to analysis the structural, optical, morphological, magnetic, and electrochemical properties of these nanocomposites. XRD analysis results indicate the presence of the SnFe₂O₄ phase and preferred peak in (311) plane for the super activated carbon/SnFe₂O₄ NPs nanocomposite. Various methods, such as Scherrer, Williamson–Hall, Rietveld, Halder–Wagner, and McMaille, were used to calculate structural parameters. FESEM images displayed the creation of very small structures with cubic and polyhedral shapes, showing cluster growth in SnFe₂O₄ phase. The most significant absorption of light was observed in the super activated carbon/SnFe₂O₄ sample in order of 10⁵ cm⁻¹. The band gap of the samples was found to be in the range of E_g = 2.54–4.70 eV, indicating that the materials exhibit semiconductor properties. Additionally, BET analysis revealed a notably high specific surface area of 2840.3 m²/g in the super activated carbon/SnFe₂O₄ nanoparticles nanocomposite. From the UV–Vis analysis, the values of refractive index (n), extinction coefficient (k), dielectric constant ( \(\epsilon\) $ϵ$ ), Urbach energy (E_u), and reflection coefficient were studied. The analysis using VSM showed that nanoparticles exhibit ferromagnetic properties. FTIR analysis results confirmed the vibrations associated with the presence of metal oxides Sn–O and Fe–O. The existence of these metal oxide bonds suggests the formation of a tin ferrite spinel structure. The CV results demonstrate that lithium ions can penetrate the SnFe₂O₄ spinel structure due to the presence of the lithium salt electrolyte.