Electrochemical properties of K and S doped LiMn2O4 studied by GITT and EIS

K and S doped LiMn2O4 (general composition: Li1-xKxMn2O4-ySy, x=0.01, 0.02; y=0.01, 0.02, 0.03) is a high-performance cathode material for lithium-ion batteries. Its synthesis through sol-gel route is facile, efficient and eco-friendly, while giving a uniform nanocrystalline material with strictly controllable composition. In the present work, LKMOS has been synthesized with four different combinations of potassium and sulfur dopants, giving materials with compositions of Li0.99K0.01Mn2O3.99S0.01, Li0.99K0.01Mn2O3.98S0.02, Li0.99K0.01Mn2O3.97S0.03 and Li0.98K0.02Mn2O3.99S0.01. Obtained materials has been tested in Li-ion half cells in order to determine the effect of different dopant combinations on cathode's Li+ transport kinetics, impedance and high-power performance. Materials are characterized by X-ray diffraction and X-ray fluorescence. The electrochemical performance of the materials is examined by a galvanostatic charge-discharge tests, galvanostatic intermittent titration technique and electrochemical impedance spectroscopy. Electrochemical impedance tests have shown the effect of dopant amount in both oxygen and lithium sublattice on the half-cell internal resistances. The optimal composition of K and S doped LMO cathode for high-power application has been established.