The Effects of Lithium and Oxygen Contents Inducing Capacity Loss of the LiMn2O4 Obtained at High Synthetic Temperature

Well-crystallized LiMn2O4 has been synthesized at different calcination temperatures using the melt-impregnation method. The lattice constant of LiMn2O4 increased with increasing calcination temperatures. Li/LiMn2O4cells calcined at lower temperatures (700–800°C) showed excellent cycling performances at room temperature. However, those cells calcined at higher temperature (850–900°C) exhibited abrupt capacity loss in the early stage and very poor cycle retention rate (>65%) after 50 cycles. It was considered that poor cycle performance of the spinels obtained at high temperature resulted from the lithium sublimation and oxygen deficiency during synthetic process. We found that above two factors, lithium sublimation and oxygen deficiency, were the commonly important factors to induce capacity loss in the Li/LiMn2O4 system, especially obtained at high synthetic temperature.