Preparation of fine single crystals of spinel-type lithium manganese oxide by LiCl flux method for rechargeable lithium batteries. Part 1. LiMn2O4

Abstract

Uniform fine single crystals of LiMn₂O₄ spinel were synthesized by a LiCl–Mn(NO₃)₂ flux method. The effects of reaction temperature and time on the composition, size and morphology of lithium manganese oxide were investigated by chemical, X-ray diffraction and selected area electron diffraction analyses, and SEM observation. The composition and size of the single crystals depended strongly on the heating temperature. Stoichiometric LiMn₂O₄ single crystals were yielded at 850 °C, whereas lithium-rich and lithium-poor crystals were obtained at 650–750 °C and 950 °C, respectively. Plate-like Li_1.18Mn₂O_4.28 single crystals with a thickness of less than 0.1 µm, showed a high first discharge capacity of 112 mAh g⁻¹ with a good cycle feature. The increase in the size of single crystals resulted in a decrease of the capacity at the first cycle, but did not accelerate the capacity fade over the following cycles.