Optimization of sulphur content in $LiMn_2O_{4-y}S_y$ spinels as cathode materials for lithium-ion batteries

Sulphur doped lithium manganese spinels with a nominal composition of LiMn2O4-ySy (0≤y≤0.02) were synthesized by a modified sol-gel method followed by calcinations at 300 and 650 °C in air. The prepared materials were characterized in terms of physicochemical properties using X-ray powder diffraction (XRD), differential scanning calorimetry (DSC) and electrical conductivity studies (EC). Electrochemical characteristic of Li/Li+/LiMn2O4-ySy cells was examined by galvanostatic charge/discharge tests (CELL TEST), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was shown that small amount of sulphur in LiMn2O4 spinel enhances the structural integrity of the host material and increases the electrochemical performance.