MECHANISM OF THE ELECTROCHEMICAL INSERTION OF LITHIUM INTO LIMN2O4 SPINELS

LiMn2O4-based spinels have been extensively studied as positive electr ode materials for Lithium-ion batteries. Our investigations have shown that, by using the Pechini process, the performance of these material s can be improved significantly through adjustments to the synthesis c onditions and composition by means of selective doping. This paper rep orts the results of neutron and ex situ X-ray diffraction studies perf ormed to examine the structural changes that occur during lithium ion insertion into various LixMn2O4 compositions. It appears that an order ing intercalation of lithium ions occurs in the lithium concentration range of 0.15-0.35, followed by a second-order phase transformation wh en the lithium population is close to 0.5, leading to a random lithium insertion into a single-spinel phase from x=0.5 to 1.0.