Preparation and characterization of partially substituted LiMyMn2−yO4 (M=Ni, Co, Fe) spinel cathodes for Li-ion batteries

The electrochemical and thermal behaviors of the spinels-LiMn₂O₄, LiCo_1/6Mn_11/6O₄, LiFe_1/6Mn_11/6O₄, and LiNi_1/6Mn_11/6O₄ were studied using electrochemical and thermochemical techniques. The electrochemical techniques included cyclic voltammetry, charge-discharge cycling of 2016 coin cells and diffusion coefficient measurements using Galvanostatic Intermittent Titration Technique. Better capacity retention was observed for the substituted spinels (0.11% loss per cycle for LiCo_1/6Mn_11/6O₄; 0.3% loss per cycle for LiFe_1/6Mn_11/6O₄; and 0.2% loss per cycle for LiNi_1/6Mn_11/6O₄) than for the lithium manganese dioxide spinel (1.6% loss per cycle for first ten cycles, 0.9% loss per cycle for 33 cycles) during 33 cycles. The Differential Scanning Calorimetry results showed that the cobalt substituted spinel has better thermal stability than the lithium manganese oxide and other substituted spinels.