Single-crystal studies of electrochemically delithiated LiMn2O4

Single-crystals of LiMn2O4 spinel have been synthesized and investigated by X-ray diffraction (XRD). On the basis of the systematic absences, the cubic space-group Fd m was chosen with a=8.245(4) . The crystals were then delithiated electrochemically to three different voltages: 4.25, 4.11 and 4.10 V vs Li/Li+. The lithium-depleted single-crystals obtained at 4.25 and 4.11 V exhibited a 7×7×7 superlattice cell with aʹ=56.49(2) and 57.13(3) A, respectively. At 4.10 V, the crystals show a 3×3×3 superlattice with aʹʹ=24.41(1) ?. These superlattices can be ascribed to ordering of manganese ions with different oxidation-states.