SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF DEFECT SPINELS IN THE LITHIUM-MANGANESE-OXIDE SYSTEM

Lithium-manganese-oxides prepared at moderate temperatures are under investigation as insertion electrodes for rechargeable lithium batteries. The structures of two defect-spinel compounds synthesised by the reaction of MnCO3 and Li2CO3 at 400-degrees-C are reported. The cation distributions in the structures were determined by neutron-diffraction to be {Li.85 square .15}8a[Mn1.74Li.26]16dO4 and (Li.87 square .13}8a[Mn1.71Li.29]16dO4, where 8a and 16d refer to the tetrahedral and octahedral sites of the prototypic spinel space group Fd3m, respectively. The structures are discussed in relation to the spinel system Li2O.yMnO2 (y greater-than-or-equal-to 2.5).