The Temperature Effect on the Electrochemical Performance of Sulfur-Doped LiMn₂O₄ in Li-Ion Cells

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.