In this manuscript, we describe the results of our recent studies on carbon aerogels derived from natural starches. A facile method for the fabrication of carbon aerogels is presented. Moreover, the complete analysis of the carbonization process of different starch aerogels (potato, maize, and rice) was performed using thermogravimetric studies combined with a detailed analysis of evolved decomposition products. The prepared carbon aerogels were studied in terms of their morphology and electrical properties to relate the origin of starch precursor with final properties of carbon materials. The obtained results confirmed the differences in carbon aerogels’ morphology, especially in materials’ specific surface areas, depending on the botanical origin of precursors. The electrical conductivity measurements suggest that carbon aerogels with the best electrical properties can be obtained from potato starch.

Nickel and sulfur doped lithium manganese spinels with a nominal composition of LiMn_2−xNi_xO_4–yS_y (0.1 ≤ x ≤ 0.5 and y = 0.01) were synthesized by a xerogel-type sol-gel method followed by subsequent calcinations at 300 and 650 °C in air. The samples were investigated in terms of physicochemical properties using X-ray powder diffraction (XRD), transmission electron microscopy (EDS-TEM), N₂ adsorption-desorption measurements (N₂-BET), differential scanning calorimetry (DSC), and electrical conductivity studies (EC). Electrochemical characteristics of Li/Li⁺/LiMn_2−xNi_xO_4–yS_y cells were examined by galvanostatic charge/discharge tests (CELL TEST), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The XRD showed that for samples calcined at 650 °C containing 0.1 and 0.2 mole of Ni single phase materials of Fd-3m group symmetry and nanoparticles size of around 50 nm were obtained. The energy dispersive X-ray spectroscopy (EDS) mapping confirmed homogenous distribution of nickel and sulfur in the obtained spinel materials. Moreover, it was revealed that the adverse phase transition at around room temperature typical for the stoichiometric spinel was successfully suppressed by Ni and S substitution. Electrochemical results indicated that slight substitution of nickel (x = 0.1) and sulfur (y = 0.01) in the LiMn₂O₄ enhances the electrochemical performance along with the rate capability and capacity retention.

The application of modified spinel materials in commercial systems relates to the verification of their parameters under different conditions. Hence, in this study, the influence of temperature on the electrochemical behavior of sulfur-doped spinel (LiMn₂O_3.97S_0.03), with reference to stoichiometric spinel (LiMn₂O₄), was investigated. The electrochemical characteristics of Li-ion cells based on the fabricated spinels were investigated using galvanostatic charge–discharge tests (GCDT), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results show that introducing sulfur into the spinel structure improves the electrochemical properties at each of the studied temperatures (3, 22 and 61 °C). LiMn₂O_3.97S_0.03 exhibits higher specific capacities, enhanced diffusivity and charge–discharge rates (particularly at low temperatures), and much better cycling stability, regardless of the testing conditions. Our research proves that an S-doping system is a better alternative to LiMn₂O₄ in the context of working parameters, while maintaining environmental friendliness and low manufacturing costs.