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

Lithium-manganese-oxides prepared at moderate temperatures are under i nvestigation as insertion electrodes for rechargeable lithium batterie s. The structures of two defect-spinel compounds synthesised by the re action of MnCO3 and Li2CO3 at 400-degrees-C are reported. The cation d istributions 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 octah edral sites of the prototypic spinel space group Fd3m, respectively. T he structures are discussed in relation to the spinel system Li2O.yMnO 2 (y greater-than-or-equal-to 2.5).